Doc #128 — HF Radio Network for National and International Communication

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RECOMMENDED ACTIONS

Phase 1: Months 0–3 (Immediate)

1. Activate AREC and NZART network — Contact all NZART branch presidents; activate AREC callout procedures; establish initial regional check-in schedule. Cost of delay: every day without an organized HF network is a day without reliable international communication capability.

2. Establish trans-Tasman contact — Begin calling on 14.295 MHz USB and 7.095 MHz LSB for Australian stations. Coordinate bilateral emergency net schedule. Cost of delay: delays intelligence-gathering about Australia’s status and delays diplomatic coordination.

3. Assign amateur liaison officers to all regional Civil Defence ECCs — Formalize the AREC–Civil Defence relationship for sustained (not temporary) operation.

4. Begin HF equipment inventory — Through NZART branches, catalogue all HF-capable equipment (amateur, marine, commercial) by location, capability, and condition. Feed into national skills census (Doc #8).

5. Authorize amateur frequencies for emergency government traffic — Formal legal authorization under emergency management legislation.

6. Establish monitoring on international frequencies — Assign operators to monitor 14.300 MHz USB (international emergency) and attempt contact with Pacific Islands, South America, Southern Africa.

7. Begin daily national and regional nets — Per the schedule in Section 5.3.

Phase 1: Months 3–12

8. Launch accelerated operator training program — Target 300–500 new licensees in first 6–12 months (dependent on trainer availability and candidate pool — see Section 9.2). Prioritize geographic areas with operator shortages.

9. Establish regional node backup power — Battery banks and solar panels at all 13 regional nodes, ensuring 48+ hours of operation without grid power.

10. Stockpile and redistribute spare equipment — Centralize spare transceivers, components, coaxial cable. Recover equipment from non-operational maritime and commercial sources.

11. Deploy digital mode capability — JS8Call and Winlink stations at all regional nodes. Train operators in digital mode operation.

12. Begin CW (Morse code) training — For international link operators and as general skill expansion.

13. Establish Chatham Islands HF link — Ensure reliable daily communication with the Chathams.

14. Begin systematic propagation monitoring — Log and analyse propagation data to build a post-event propagation database. Compare with pre-war conditions to assess nuclear winter ionospheric effects.

Phase 2: Years 1–3

15. Expand community-level coverage — Train community radio operators for settlements without amateur presence. Target: every community of 300–500+ people has HF communication capability, with priority given to geographically isolated communities regardless of size (see Section 13.2).

16. Establish maritime HF net — As sailing vessel fleet develops (Doc #138), integrate maritime communication into the national HF network.

17. Begin antenna experimentation for degraded propagation — If nuclear winter reduces MUF, develop and test antenna systems optimized for lower frequencies.

18. Coordinate with Australian network on relay to other regions — Australia may have better propagation paths to some destinations; use relay to extend NZ’s communication reach.

Phase 3–5: Years 3–10+

19. Begin transition planning to locally fabricated equipment — Per Doc #131. Initial target: CW transmitters from local materials.

20. Develop NZ-made antenna components — Wire drawing, insulator production, feedline fabrication. Ensure antenna systems can be maintained indefinitely.

21. Expand international network — As trade routes develop (Doc #141), establish communication with new trading partners. HF communication precedes and enables maritime trade.

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ECONOMIC JUSTIFICATION

Resource Commitment

Establishing and sustaining a national HF radio network requires a credible allocation of skilled labour. The following estimates cover the initial three-year build-out:

Radio engineers and technical staff. Regional nodes require trained operators who can diagnose and repair transceiver faults, construct and tune antenna systems, and manage backup power. Estimate: 2 qualified technicians per regional node, 13 nodes, plus a national coordination cell of 3–5. Total: approximately 30–35 person-years in Year 1, rising as the training pipeline produces additional technicians.

Operators. Staffing twice-daily national nets, six daily international contact attempts, and 13 regional nets with adequate roster depth requires a minimum of 4 operators per node at full deployment (to allow 24-hour coverage and day-off rotation). That is roughly 52 active operators at node level, plus perhaps 200 community-level operators covering outlying settlements by end of Year 2. Not all of these positions are full-time — many operators contribute part-time alongside other recovery roles. Aggregate estimate: 50–80 full-time-equivalent person-years annually at network maturity.

Antenna builders and riggers. Initial antenna installation across 13 regional nodes plus 200+ community stations requires physical construction: erecting masts, running feedline, installing ground radials. Estimate: 0.5–1 person-week per site, or roughly 5–15 person-years for the initial build-out phase (Years 1–2).

Trainers. The operator expansion target of 300–500 new licensees in the first 6–12 months, and ongoing community training thereafter, requires instructors. Estimate: 10–20 experienced operators repurposed as full-time trainers during the peak training phase (Months 1–18), or approximately 15–30 person-years over the first two years. The trainer estimate assumes experienced operators are willing and available to teach rather than staff operational nets — a potential tension that must be managed.

Total estimated labour commitment (Years 1–3): Approximately 150–250 person-years across all roles. This is a modest commitment relative to the scale of other recovery programs — less than the labour required to maintain a single mid-sized hospital or a regional roading crew.

The Counterfactual: No Long-Range Communication

The relevant comparison is not “HF radio versus modern telecommunications.” Modern telecommunications are either functional (in which case HF is a supplement and backup) or degraded (in which case HF is the only option). The economic question is what NZ loses if HF capacity is not built.

Without HF, NZ has no international communication once submarine cable endpoints fail. The Northern Hemisphere cable termination points are destroyed or unattended. The NZ–Australia cable requires powered terminal equipment at both ends — if the Australian side degrades, the link fails. Satellite communication systems degrade without constellation maintenance. In that scenario, NZ is communication-isolated from every other surviving region.

The economic cost of isolation is not easily quantified, but the consequences are concrete:

• No intelligence about conditions in Australia, the Pacific, or South America. Government planning proceeds on assumption rather than information.
• No trade coordination. The sailing vessel trade routes described in Doc #141 depend on pre-arranged contacts at destination ports, weather and navigation information exchanged at sea, and confirmed availability of goods before a vessel departs. Without HF communication, sailing voyages are essentially blind.
• No diplomatic relationships. The international relationships NZ needs to rebuild — with Australia, Pacific Island nations, South American trading partners — require ongoing communication to develop and sustain.
• No distress coordination. Vessels in distress have no way to summon assistance, reducing the feasibility and safety of ocean voyages on which trade recovery depends.

These are not edge cases. They are the central requirements for economic recovery. Trade routes that cannot communicate are trade routes that do not function.

Breakeven Analysis

HF radio is not one option among several for international communication in the post-cable, post-satellite scenario. It is the only option. Breakeven analysis in the conventional sense — at what point do the benefits exceed the costs — does not apply in the normal way, because the alternative is not a cheaper communication system but no long-distance communication at all.

The more useful framing is: what does 150–250 person-years of investment buy?

• A functioning international communication link from Day 1 (using existing equipment and operators, no build time required)
• A domestic communication backbone that does not depend on the same grid, fiber, and cell tower infrastructure that is subject to degradation
• A trained operator corps of 1,000+ people by Year 3, capable of sustaining the network for decades
• Antenna systems and operator skills that can be reproduced from entirely local materials and knowledge if all imported equipment eventually fails

No other communication technology achieves this at any cost. Satellite systems require ongoing manufacturing and launch capability; submarine cables require Northern Hemisphere endpoints; cellular and fiber networks require complex imported equipment and continuous grid power. HF radio, once established, requires only skilled operators and simple maintainable hardware.

Opportunity Cost

The labour and materials committed to the HF network are diverted from other recovery tasks. The honest accounting is:

• 150–250 person-years over three years is the primary cost. These are skilled people — technicians, operators, trainers — who could otherwise contribute to food production, medical care, or infrastructure maintenance.
• Equipment from existing amateur stocks is not a cost in the sense of manufacturing — it already exists. The cost is the opportunity cost of not using that equipment for other purposes (which are essentially nil — amateur radio equipment has few alternative uses in a recovery context).
• Spare parts and stockpiling diverts some materials (copper wire, electronic components, coaxial cable) from other uses. The quantities involved are small compared to total NZ stocks.

Against this, the opportunity cost of not building the network is the entire value of international trade, diplomacy, and maritime coordination that the network enables. A single successful trade voyage to Australia — returning with food, medicine, or industrial supplies — likely exceeds the entire three-year labour cost of the HF network in economic value. There is no credible argument that the labour is better spent elsewhere.

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1. WHY HF RADIO, AND WHY NOW

1.1 The unique capability of HF

HF radio (3–30 MHz) propagates via ionospheric refraction — radio waves bounce off the ionosphere and return to earth at distances ranging from hundreds to thousands of kilometres.¹ This gives HF a capability that no other readily available technology provides: point-to-point communication over transoceanic distances without any intermediate infrastructure. No satellites, no undersea cables, no cell towers, no internet backbone. A transmitter, an antenna, a receiver, and the ionosphere.

This matters for two distinct reasons:

International communication. NZ’s submarine cable connections to the outside world terminate at landing points in Australia and the United States.² If the cable endpoints or their supporting infrastructure in the Northern Hemisphere are destroyed or degraded, NZ loses internet and telephone connectivity to most of the world. Even the NZ–Australia cable link depends on powered terminal equipment at both ends. HF radio can reach Australia, the Pacific Islands, South America, and Southern Africa directly, with no infrastructure dependency beyond the stations at each end.

Domestic resilience. NZ’s domestic telecom network depends on a chain of equipment: cell towers (battery-backed, typically 4–8 hours without grid power, with complex electronics that degrade over years), fiber-optic networks (robust cable but fragile terminal equipment), and copper landlines (the most resilient layer but increasingly decommissioned).³ If any layer degrades — through equipment failure, spare parts depletion, or localized grid problems — HF radio provides communication between any two points in NZ from simple, maintainable equipment.

1.2 Why begin immediately

The cost of delay is asymmetric. Establishing an HF network while modern telecom is functional is considerably easier than doing so afterward: coordination can happen by phone and email, equipment can be tested against known-good communication links, operators can train without the pressure of being the only communication channel available. The task still requires sustained organizational effort — activating a volunteer network across 13 regions, securing backup power, and formalizing government-amateur coordination — but these steps are manageable while existing communication infrastructure supports them. Attempting to build the network after telecom has degraded means doing all of this the hard way.

More importantly, international communication is needed from Day 1. The government needs to establish contact with Australia, assess the state of the Pacific, and begin coordinating whatever regional cooperation is possible. HF radio may be the only means of doing this, especially if submarine cable infrastructure is compromised at the Northern Hemisphere endpoints.

Assumption: This document assumes NZ’s amateur radio community is substantially intact — that most licensed operators are alive, in NZ, and have access to their equipment. This is reasonable given NZ’s physical distance from the conflict, but some operators may be travelling overseas at the time of the event.

1.3 What HF radio cannot do

HF radio is not a replacement for modern telecommunications. It is slow (voice or low-speed data), limited in bandwidth (one conversation per frequency at a time), subject to propagation conditions that change by hour and season, and requires skilled operators. It cannot carry internet traffic in any meaningful sense. It cannot support the kind of always-on, high-bandwidth communication that modern society takes for granted.

What it can do: pass critical messages between specific stations, maintain scheduled contact with international partners, provide a communication backbone when nothing else works, and support low-bandwidth digital data transfer (email-like messages, position reports, weather data) through digital HF modes.

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2. NZ’S EXISTING HF RADIO CAPABILITY

2.1 Amateur radio operators

The New Zealand Association of Radio Transmitters (NZART), founded in 1926, is the national organization for amateur radio operators in NZ.⁴ NZART is affiliated with the International Amateur Radio Union (IARU) and represents NZ amateurs internationally.

Operator numbers. NZ has approximately 3,000–4,000 licensed amateur radio operators, though the exact number fluctuates and not all licensees are active.⁵ The Radio Spectrum Management (RSM) division of the Ministry of Business, Innovation and Employment (MBIE) administers amateur radio licensing in NZ. License classes include General Amateur Operator (the standard license, permitting operation on all amateur bands with up to 1 kW output power) and Limited Amateur Operator (restricted bands and power).⁶

Estimate: Of the approximately 3,000–4,000 licensees, perhaps 1,500–2,500 are actively operating at any given time, based on typical amateur radio activity rates. Of these, a substantial fraction have HF-capable equipment. The number with equipment capable of reliable long-distance HF communication (100W+ transceivers, effective antennas) is probably 1,000–2,000. These figures require verification through the skills census (Doc #8) and direct survey of the amateur community.

Demographics. The amateur radio population skews older — this is a global pattern, not unique to NZ. Many operators are retired or semi-retired, with decades of experience. This is both an advantage (deep expertise, often available full-time) and a vulnerability (aging population, skills concentration in a shrinking cohort). Expanding the operator pool is addressed in Section 9.

Geographic distribution. NZART is organized into approximately 80 branches across both islands, from Kaitaia to Invercargill.⁷ This provides geographic coverage of most populated areas. However, distribution is uneven — urban areas (Auckland, Wellington, Christchurch) have higher concentrations, while some rural areas may have few operators. The branch structure provides a natural organizational framework for a regional node network.

2.2 AREC — Amateur Radio Emergency Communications

AREC (Amateur Radio Emergency Communications) is the emergency communication arm of NZART, established to provide communication support during emergencies and civil defence events.⁸ AREC volunteers are trained in emergency communication procedures and work alongside New Zealand’s emergency management agencies.

Existing capabilities:

• Trained operators with experience in emergency communication protocols
• Established relationships with the National Emergency Management Agency (NEMA, formerly MCDEM) and regional Civil Defence Emergency Management (CDEM) groups⁹
• Deployment experience in NZ disasters including the Christchurch earthquakes (2010–2011), Kaikōura earthquake (2016), and Cyclone Gabrielle (2023)¹⁰
• Standard operating procedures for emergency activation and message handling
• Equipment pre-positioned at some Civil Defence Emergency Coordination Centres (ECCs)

Honest assessment: AREC’s capability is real but should not be overstated. It is a volunteer organization. Activation depends on individual operators being available and willing. Equipment varies in capability and condition. AREC provides a communication supplement in emergencies, not a comprehensive network. The scenario described in this document — permanent, not temporary — demands a more structured and sustained effort than AREC’s existing emergency deployment model.

2.3 Government and commercial HF

NZ’s government and commercial sectors have some HF capability:

Maritime HF. Maritime New Zealand operates or contracts HF maritime communication services. NZ-flagged vessels and fishing boats carry marine HF radios — these operate on marine HF frequencies (primarily 4, 6, 8, 12, and 16 MHz bands) and are an existing asset.¹¹ The number of HF-equipped vessels in NZ waters varies but is likely in the hundreds (commercial fishing fleet, coastal freighters, offshore sailing vessels). These radios can be repurposed or their operators recruited for the national network. Historically, Taupo Maritime Radio (ZLM) and Auckland Maritime Radio (ZLD) provided HF coast station services.¹²

Police and emergency services. NZ Police and some emergency services retain some HF capability as backup communications, though the extent has diminished as modern telecommunications improved. The actual current state of government HF capability requires verification.

Defence Force. The New Zealand Defence Force (NZDF) operates HF radio for military communications, including naval HF aboard RNZN vessels and army field HF sets.¹³ NZDF HF capability is likely the most professionally maintained government HF asset and should be integrated into the national network plan.

Commercial. Some remote stations, farms, and businesses in areas with poor cellular coverage use HF or VHF radio. The Chatham Islands have historically depended on HF for communication with the mainland.¹⁴

2.4 Repeater and VHF/UHF networks

NZART and its branches maintain a network of VHF and UHF repeaters across NZ — stations on hilltops and mountain sites that extend the range of handheld and mobile radios from line-of-sight (tens of kilometres) to regional coverage (100+ km per repeater).¹⁵ These repeaters are valuable for regional communication but they are infrastructure-dependent: they require power (usually grid or solar), antenna systems, and electronic equipment that degrades over time. They do not provide international communication.

The repeater network is a useful complement to the HF network for regional coordination, particularly in the early phases when repeater infrastructure is functional. As equipment degrades without imported replacement parts, the network will contract. The HF network, which depends only on the stations at each end, is more sustainable long-term.

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3. HF PROPAGATION — WHAT WORKS FROM NZ

3.1 Ionospheric propagation basics

HF radio signals propagate by refraction in the ionosphere — layers of ionized gas at 80–400 km altitude, created by solar ultraviolet radiation.¹⁶ The ionosphere’s ability to refract radio waves depends on the frequency used, the time of day, the season, the solar cycle (approximately 11 years), and geomagnetic conditions.

Key principles for NZ operators:

• Lower frequencies (3–10 MHz) are refracted more strongly and work better at night, when the lower ionospheric layers (D-layer) that absorb these frequencies disappear. Good for medium to long distances at night.
• Higher frequencies (10–30 MHz) require stronger ionization and work better during daytime, especially during solar maximum. Good for long distances during the day.
• The Maximum Usable Frequency (MUF) is the highest frequency that will be refracted back to earth for a given path at a given time. Transmitting above the MUF means the signal passes through the ionosphere into space. The MUF varies continuously.¹⁷
• The skip zone is the area between the limit of ground-wave coverage (typically 50–100 km for HF) and the point where the first sky-wave returns to earth. Within the skip zone, no signal is received. Skip distance varies with frequency and ionospheric conditions.

3.2 NZ-specific propagation paths

NZ’s geographic position (approximately 35–47°S latitude, 166–178°E longitude) creates specific propagation characteristics:

NZ to Australia (2,000–3,000 km). The most important path. This is a medium-distance path well-suited to HF. Reliable communication is possible on multiple bands depending on time of day:¹⁸

• Daytime: 14 MHz (20m band), 18 MHz (17m band), 21 MHz (15m band) — often open during daylight hours, particularly around solar maximum
• Night: 7 MHz (40m band), 3.5 MHz (80m band) — reliable nighttime paths
• Transition periods (dawn/dusk): 10 MHz (30m band) — often useful during grey-line propagation
• The 40m band (7 MHz) is frequently described as the “workhorse” for trans-Tasman communication, usable for much of the 24-hour cycle¹⁹

NZ to Pacific Islands (1,500–4,000 km). Similar distance range to Australia. Fiji, Tonga, Samoa, Cook Islands are all reachable on the same bands. Propagation is generally favourable — equatorial and near-equatorial ionosphere tends to be well-ionized.

NZ to South America (9,000–11,000 km). A long path requiring multiple ionospheric hops. Best on higher bands (14–21 MHz) during daylight on the path. Propagation is often viable but less consistent than the trans-Tasman path. Chile and Argentina (the closest South American countries) are approximately 9,000–10,000 km from NZ.²⁰

NZ to Southern Africa (11,000–12,000 km). Similar to South America in distance and difficulty. South Africa has a strong amateur radio community (SARL — South African Radio League) which would be a key contact point.²¹

NZ to Northern Hemisphere. Distances of 15,000–20,000 km (e.g., Wellington to London approximately 18,900 km, Wellington to Tokyo approximately 9,500 km by great circle).²² In the scenario under consideration, Northern Hemisphere stations may be severely reduced. Propagation over these distances is possible but requires favorable conditions and higher power. This is a lower priority than Southern Hemisphere contacts but should be attempted regularly to assess what communication is possible.

Domestic NZ (200–2,000 km). Internal NZ communication by HF uses near-vertical incidence skywave (NVIS) on lower frequencies (3.5–7 MHz). NVIS involves transmitting at a steep angle so that the signal is refracted straight back down, providing coverage within approximately 0–500 km without a skip zone.²³ This is ideal for domestic communication between NZ cities and regions.

3.3 Nuclear effects on HF propagation

The nuclear exchange scenario introduces specific propagation effects:

Electromagnetic pulse (EMP). Nuclear detonations generate EMP that can disrupt or damage electronic equipment. However, the scenario involves Northern Hemisphere detonations approximately 8,000–18,000 km from NZ. The direct EMP effects (E1, E2, E3 components) attenuate rapidly with distance and are primarily line-of-sight from the detonation.²⁴ NZ is unlikely to experience direct EMP damage from Northern Hemisphere detonations. Assumption: NZ radio equipment is physically undamaged by EMP. If high-altitude nuclear detonations occur in the Southern Hemisphere (which is not the primary scenario but cannot be ruled out), this assumption would need revision.

Ionospheric disturbance. Nuclear detonations in the upper atmosphere cause intense ionization that can black out HF propagation over large areas for hours to days. The 1962 Starfish Prime test (1.4 megaton, 400 km altitude over Johnston Atoll in the Pacific) disrupted HF communication across much of the Pacific for several hours and caused enhanced ionization effects lasting days.²⁵ In a 4,400-warhead exchange, the cumulative effect on the Northern Hemisphere ionosphere would be severe and prolonged. Effects on the Southern Hemisphere ionosphere are less certain — the geomagnetic field tends to confine charged particles to their hemisphere of origin, but some cross-equatorial effects are likely.²⁶

Estimate: HF propagation from NZ may experience disruption lasting hours to days during and immediately after the exchange, with possible intermittent degradation for weeks thereafter as the ionosphere restabilizes. Propagation to Northern Hemisphere locations may be severely affected for longer. Propagation between Southern Hemisphere locations (NZ–Australia, NZ–South America, NZ–Southern Africa) should recover to near-normal conditions within days to weeks. This estimate is uncertain — there is no precedent for the ionospheric effects of a full-scale nuclear exchange, and models of atmospheric nuclear effects carry significant uncertainty.²⁷

Nuclear winter effects on propagation. The 5–15°C surface cooling from nuclear winter will affect the upper atmosphere as well. Changes to stratospheric temperature and composition (soot injection, ozone depletion) could alter ionospheric density and structure. The direction and magnitude of these effects are not well-characterized. Some models suggest reduced ionospheric electron density due to reduced solar UV reaching the upper atmosphere (from soot blocking), which would lower the MUF and reduce the usable frequency range.²⁸ Other effects — changes to the D-layer absorption, altered geomagnetic activity patterns — are speculative. This is a genuine unknown. Operators should monitor propagation conditions empirically and adapt frequency planning accordingly rather than relying on pre-war propagation predictions.

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4. FREQUENCY PLANNING

4.1 Amateur HF bands available in NZ

NZ amateur radio operators have access to the following HF bands, as allocated by the Radio Spectrum Management authority:²⁹

Band	Frequency Range	Primary Use in This Network
160m	1.800–1.875 MHz	Short-range domestic, limited use
80m	3.500–3.900 MHz	Domestic NVIS, nighttime regional
40m	7.000–7.300 MHz	Domestic + trans-Tasman workhorse
30m	10.100–10.150 MHz	Digital modes, transition band
20m	14.000–14.350 MHz	Primary international daytime
17m	18.068–18.168 MHz	International, solar-dependent
15m	21.000–21.450 MHz	International daytime, long-distance
12m	24.890–24.990 MHz	International, solar-dependent
10m	28.000–29.700 MHz	International, high solar activity only

4.2 Recommended frequency allocation for the national network

The network should designate specific frequencies within each band for scheduled national and international nets (organized group communication sessions). This prevents the confusion of operators searching for activity across wide band segments.

Domestic net frequencies (NVIS, 80m and 40m):

• 3.600 MHz LSB — National domestic morning net
• 3.650 MHz LSB — Regional nets (staggered schedule)
• 7.090 MHz LSB — National domestic afternoon/evening net
• 7.040 MHz — Digital modes (JS8Call/Winlink) domestic

Trans-Tasman and Pacific frequencies:

• 7.095 MHz LSB — NZ–Australia evening net
• 14.295 MHz USB — NZ–Australia/Pacific daytime net
• 14.110 MHz — Digital modes international

Long-distance international frequencies:

• 14.300 MHz USB — International emergency/calling frequency (established convention)³⁰
• 21.360 MHz USB — South America/Africa daytime attempts
• 18.150 MHz USB — Alternative international

Emergency and calling:

• 5.680 MHz — International aeronautical distress (monitoring only)
• 14.300 MHz USB — International emergency net

These allocations should be coordinated with the Australian Wireless Institute of Australia (WIA) and any other reachable national amateur radio organizations to ensure both sides are listening on agreed frequencies at agreed times.³¹

4.3 Operating modes

Single sideband (SSB) voice. The standard mode for HF voice communication. Upper sideband (USB) is conventional above 10 MHz; lower sideband (LSB) below 10 MHz. Voice is the fastest way to exchange information in real time and requires no special equipment beyond a standard HF transceiver.

Morse code (CW). Continuous-wave Morse code is the most efficient HF mode in terms of signal-to-noise ratio — a CW signal can be copied under conditions where voice is unintelligible. CW also requires the simplest equipment (a transmitter need only be switched on and off, with no complex modulation). The limitation is that both operators must know Morse code. Many older NZ amateurs are proficient; younger operators less so. CW training should be included in the operator expansion program (Section 9).

JS8Call. A digital HF mode designed specifically for weak-signal keyboard-to-keyboard communication over HF. JS8Call is built on the WSJT FT8 protocol but adapted for message relay and store-and-forward operation.³² It can decode signals far below the noise floor that voice cannot penetrate. It requires a computer (or single-board computer like a Raspberry Pi) connected to the HF transceiver via a sound card interface. JS8Call supports message relay — stations can pass messages through intermediate stations to reach distant endpoints. Several NZ amateur operators already run JS8Call nodes, particularly in the Wellington and Canterbury regions; the existing community provides a nucleus for network-wide deployment.

Winlink. A global radio email system that uses HF radio to send and receive email messages. Winlink stations (Radio Message Servers, or RMS) act as gateways. In the post-event scenario, the internet-connected Winlink infrastructure will likely be unavailable, but Winlink can operate in peer-to-peer mode (station-to-station email without internet) or through locally established relay nodes.³³ Many NZ amateurs already have Winlink capability.

RTTY and other digital modes. Radioteletype (RTTY) and other digital modes (PSK31, OLIVIA) offer various tradeoffs between speed, error correction, and weak-signal performance. These are secondary to JS8Call and Winlink but some operators will have experience and equipment for them.

Recommendation: The network should use SSB voice as the primary mode for scheduled nets and real-time coordination, CW as a backup when propagation is poor, and JS8Call/Winlink for store-and-forward message handling and formal traffic.

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5. NETWORK ARCHITECTURE

5.1 Design principles

The network architecture must balance three goals: geographic coverage (every region can communicate), reliability (no single point of failure), and sustainability (the network can function for years with maintainable equipment).

Decentralized by design. HF networks are inherently point-to-point — any station can communicate with any other station without intermediate infrastructure. The network architecture should take advantage of this rather than creating a fragile hub-and-spoke model. If a regional node goes down, stations in that region can still reach other nodes directly.

Scheduled operations. Unlike the always-on nature of modern telecom, HF networks operate most efficiently on schedules. Stations know when to listen and on which frequencies, reducing the problem of two stations searching for each other across bands and time.

Layered. The network operates on three layers:

1. National coordination — daily nets connecting regional nodes
2. Regional communication — regional nets connecting communities within each region
3. International contact — scheduled sessions with Australia and other international stations

5.2 Regional node structure

The network should be organized around regional nodes, each with at least one well-equipped station and experienced operator. A sensible structure based on existing NZART branch geography and NZ Civil Defence regions:

Region	Node Location(s)	Key Coverage
Northland	Whangārei	Far North, Kaipara
Auckland	Auckland (multiple)	Greater Auckland, Hauraki
Waikato	Hamilton	Waikato, Coromandel
Bay of Plenty	Tauranga, Rotorua	Eastern Bay, Taupō
East Coast	Gisborne, Napier	Gisborne, Hawke’s Bay
Taranaki–Whanganui	New Plymouth, Whanganui	Taranaki, Manawatū
Wellington	Wellington, Palmerston North	Greater Wellington, Wairarapa
Nelson–Marlborough	Nelson, Blenheim	Top of South
Canterbury	Christchurch	Canterbury Plains, Ashburton
West Coast	Greymouth	Hokitika, Westport
Otago	Dunedin	Central Otago, Queenstown
Southland	Invercargill	Southland, Stewart Island
Chatham Islands	Waitangi	Chatham Islands

Each regional node should have:

• At least one station capable of 100W output on 80m and 40m bands (NVIS domestic coverage)
• At least one station capable of 100W output on 20m band (international)
• Effective antennas (see Section 7)
• Backup power capability (battery bank, solar panels, or generator — see Section 8)
• At least two trained operators to allow roster rotation
• Digital mode capability (JS8Call or Winlink)

5.3 Scheduled net operations

National morning net (daily, 0800 NZST):

• Frequency: 3.600 MHz LSB
• Net control: rotating between Wellington and Christchurch
• Purpose: situational awareness, traffic list (messages waiting), emergency announcements
• Duration: 30–60 minutes
• All regional nodes check in; pass traffic as needed

National evening net (daily, 1900 NZST):

• Frequency: 7.090 MHz LSB
• Purpose: end-of-day reports, traffic handling, coordination for next day
• Duration: 30–60 minutes

Regional nets (daily, times staggered by region):

• Frequency: 3.650 MHz LSB (North Island regions) / 3.600 MHz LSB (South Island regions, offset timing from national net)
• Purpose: local coordination, message collection from outlying stations
• Duration: 15–30 minutes per region

International nets (see Section 6):

• Multiple daily scheduled sessions on 40m and 20m

5.4 Message handling: the radiogram system

Formal traffic handling — passing written messages accurately through the network — uses the radiogram system, which is well-established in amateur radio practice.³⁴ A radiogram is a structured message format:

• Preamble: Message number, precedence (routine/welfare/priority/emergency), station of origin, check (word count), place of origin, time filed, date
• Address: Recipient name, address, telephone (if applicable)
• Text: The message body, limited to 25 words for standard messages (longer messages are sent as multiple parts)
• Signature: Sender name and address

This format ensures messages are transmitted, received, relayed, and delivered with minimal error. Precedence levels allow the network to prioritize traffic.

AREC operators are already trained in traffic handling. This existing capability is one of the strongest arguments for building the national network on the amateur radio foundation rather than starting from scratch.

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6. INTERNATIONAL COMMUNICATION

6.1 Priority contacts

Australia — highest priority. Australia is NZ’s most important international partner in any scenario. The Wireless Institute of Australia (WIA) is the Australian national amateur radio organization, with approximately 15,000–16,000 licensed operators — a substantially larger community than NZ’s.³⁵ Australian amateur radio operators are concentrated in the eastern states (New South Wales, Victoria, Queensland), which face NZ across the Tasman.

The trans-Tasman HF path is well-characterized and reliable. Thousands of contacts are made between NZ and Australian amateurs every year under normal conditions. The 40m band (7 MHz) provides near-24-hour coverage for this path; the 20m band (14 MHz) provides excellent daytime long-distance coverage.

Objective: Establish daily scheduled contact with Australian amateur stations within the first 24–48 hours. Coordinate a bilateral NZ–Australia emergency net with agreed frequencies, schedules, and traffic handling procedures. This net becomes the primary channel for government-to-government communication until or unless other channels (submarine cable, satellite) are confirmed operational.

Pacific Islands — high priority. Fiji, Tonga, Samoa, Cook Islands, and other Pacific nations have small but active amateur radio communities. These nations are NZ’s nearest neighbours and are likely in severe distress — many are import-dependent with minimal domestic production capability. Establishing contact allows assessment of their situation and coordination of whatever assistance NZ can provide.

South America — medium priority. Chile and Argentina are the closest South American countries (approximately 9,000–10,000 km). Both have active amateur radio communities (Radio Club Chileno, Radio Club Argentino). Contact with South America opens communication with another surviving region that has significant agricultural and mineral resources.

Southern Africa — medium priority. South Africa, approximately 11,000–12,000 km, has a well-developed amateur radio community (SARL). Contact provides intelligence on conditions in southern Africa and potential long-term trade relationships.

Antarctic stations — lower priority but achievable. NZ operates Scott Base in Antarctica. Other nations operate Antarctic stations. These stations have HF radio equipment and experienced operators. If staffed, they may be reachable and could serve as relay points.

6.2 International net schedule

Net	Time (NZST)	Frequency	Target
Trans-Tasman morning	0900	14.295 MHz USB	Australia (eastern states)
Trans-Tasman evening	1800	7.095 MHz LSB	Australia
Pacific Islands	1000	14.295 MHz USB	Fiji, Tonga, Samoa, Cook Is
South America attempt	0700	21.360 MHz USB	Chile, Argentina
Southern Africa attempt	1600	14.300 MHz USB	South Africa
General international	2000	14.300 MHz USB	Any reachable station

These times and frequencies are starting points. Actual propagation conditions — especially in the weeks and months after the exchange, when ionospheric conditions may be abnormal — will require empirical adjustment. Operators should log propagation conditions systematically (signal strength, noise level, band conditions) to build a post-event propagation database.

6.3 International message priorities

The first international contacts will need to establish:

1. What happened. Which regions are intact? What is the extent of destruction? This is intelligence-gathering, not confirmed information — treat all initial reports as unverified and relay them as such.
2. Who is in charge. Are functioning governments operating in Australia, Pacific Islands, South America? Who are the points of contact?
3. What is each region’s situation. Food, energy, population, infrastructure status.
4. What does each region need and what can it offer. The basis for eventual trade relationships.
5. Coordination. Agreed communication schedules, message handling procedures, relay arrangements.

This information feeds directly into the government’s international relations planning (Doc #150, #154).

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7. ANTENNA SYSTEMS

7.1 Why antennas matter more than radios

In HF radio, the antenna is typically the most important factor in station performance — more important than transmitter power.³⁶ A 100W transmitter with an excellent antenna will outperform a 1,000W transmitter with a poor antenna. Antennas are also the component most feasibly built from locally available materials, though performance varies significantly with construction quality (see Section 7.3). This is significant for long-term sustainability: even when commercial transceivers eventually fail, antennas can be fabricated indefinitely.

7.2 Recommended antenna types

Dipole antenna. The simplest effective HF antenna: two wires, each approximately one-quarter wavelength long, fed at the centre with coaxial cable or open-wire feedline. A dipole for the 40m band requires approximately 20 metres of total wire length, suspended at least 10 metres above ground. Performance is good in all directions broadside to the wire and reduced off the ends.³⁷

Materials required: copper or aluminium wire (even steel fence wire works, with reduced efficiency), insulators (ceramic, glass, or plastic), coaxial cable or ladder line, and supports (trees, masts, buildings). All of these are available in NZ.

Inverted-V dipole. A dipole supported at the centre by a single mast, with the ends sloping down to ground level. Easier to erect than a flat dipole (requires only one tall support point), and provides a more omnidirectional pattern. Slightly less efficient than a flat dipole at the same height but far easier to install.

Long wire antenna. A single wire, at least one wavelength long (40+ metres for the 40m band), run as high as possible between two supports. Fed at one end. Simple, broadband, and effective — a good choice for stations that need to cover multiple bands without multiple antennas. Requires an antenna tuner, which most modern HF transceivers include.³⁸

NVIS antenna (for domestic communication). For near-vertical incidence skywave (within-NZ communication on 80m and 40m), the ideal antenna is a horizontal dipole at low height — approximately 0.1 to 0.25 wavelength above ground (roughly 5–15 metres for 80m operation). This counterintuitive recommendation — lower is better for NVIS — results from the radiation pattern of a low dipole, which concentrates energy straight up rather than at low angles.³⁹

Vertical antenna. A quarter-wave vertical with ground radials provides low-angle radiation good for long-distance communication. Less effective for NVIS (domestic) use. A 20m-band vertical is approximately 5 metres tall — manageable. An 80m-band vertical (approximately 20 metres) is large and requires extensive radials. Verticals are most practical for the higher HF bands.

Directional antennas (Yagi). A multi-element beam antenna provides gain in one direction, improving both transmitting and receiving performance toward a specific target. A 3-element Yagi for the 20m band is approximately 10 metres wide and would need to be mounted on a rotatable mast. These are complex to build but would be valuable for dedicated international link stations (e.g., a station pointed at Australia). Some NZ amateurs already have such antennas.

7.3 Antenna construction from NZ materials

All antenna types described above can be constructed from materials available in NZ:

• Wire: Copper wire from existing stocks, recycled electrical wiring, or wire drawn from NZ copper (limited domestic supply, supplemented by recycling — see Doc #70). Aluminium wire from recycled aluminium. Steel fence wire (galvanized, abundant in pastoral NZ) works but has approximately 6–10 times the resistive loss of copper at HF frequencies, reducing effective radiated power by roughly 1–3 dB (20–50% power loss) depending on antenna length and frequency — a meaningful but often acceptable penalty when copper is unavailable.⁴⁰ For emergency antennas, almost any conductive wire will function, though efficiency degrades significantly with higher-resistance conductors.
• Insulators: Ceramic (from pottery production), glass, PVC pipe sections, or even dry hardwood. Crude insulators (e.g., hardwood) absorb moisture and develop leakage paths in wet conditions, which can reduce signal strength by 1–6 dB in rain compared to proper ceramic or glass insulators — a significant penalty in NZ’s frequently wet climate. Ceramic or glass insulators should be used wherever possible; hardwood is an emergency fallback best treated with oil or varnish to reduce moisture absorption.
• Feedline: Coaxial cable from existing stocks. When coax is unavailable, open-wire feedline (two parallel wires spaced 50–150 mm apart with periodic spacers) can be fabricated from basic materials and has lower loss than coax at HF frequencies, though it requires careful spacing consistency and must be kept clear of metal objects and walls (minimum 100–150 mm standoff) to maintain its impedance characteristics.⁴¹ This is the feedline type used before coax became common and it can be made from locally available wire and timber or plastic spacers.
• Masts: Timber poles from NZ’s extensive plantation forests and farm stocks. Radiata pine poles, farm fence posts, or purpose-cut spars. Guyed timber masts can reach 15–20 metres, though masts above 12 metres require competent rigging (guying at multiple levels, proper base anchoring) and should be erected by experienced crews to avoid injury and structural failure.

Long-term sustainability: Antenna systems can be maintained and rebuilt indefinitely from NZ materials. This is a significant advantage — even if all commercial radio equipment eventually fails, locally fabricated transmitters (Doc #131) can be connected to locally fabricated antennas.

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8. POWER SUPPLY

8.1 Power requirements for HF radio

HF radio equipment has modest power requirements:

• A typical 100W HF transceiver draws approximately 20–22A at 13.8V DC when transmitting (roughly 275–300W), and 1–2A when receiving (15–30W).⁴²
• Actual average power consumption during a communication session is much lower than the transmit figure, because operators listen more than they transmit — a typical ratio is 20–30% transmit, 70–80% receive.
• Average consumption during a 1-hour net session: approximately 40–80W average.
• Digital mode equipment (computer or single-board computer for JS8Call/Winlink) adds 5–50W depending on the device.

These are low power demands compared to most electrical equipment. A single solar panel can power an HF station.

8.2 Power sources

Grid power (baseline scenario). Under the baseline assumption of continued grid operation, most amateur stations will continue running from mains power via their existing 13.8V power supplies. This is the default for Phase 1 and likely for years thereafter.

12V battery bank. Most HF transceivers are designed to operate directly from 12V (nominal 13.8V) DC — this is standard because amateur radio has always emphasized field and emergency operation. A 100 amp-hour deep-cycle battery can power a typical HF station for approximately 10–20 hours of mixed transmit/receive operation without recharging, assuming 20–30% transmit duty cycle; higher transmit ratios (e.g., during busy net operations) reduce this to 6–12 hours. Multiple batteries extend this.

Solar panels. A 200–300W solar panel array, combined with a charge controller and battery bank, provides indefinite off-grid HF radio capability. NZ receives 3–5 peak sun hours per day depending on region and season (less during nuclear winter — see below).⁴³ A 300W panel produces approximately 900–1,500 Wh/day under normal NZ conditions (lower end: Southland in winter; upper end: Northland/Nelson in summer), more than sufficient for a busy HF station consuming 300–600 Wh/day at typical duty cycles.

Nuclear winter solar reduction. Under 5–15°C cooling with reduced sunlight from stratospheric soot, solar panel output will decrease. The magnitude depends on the extent of sunlight reduction, which is one of the most uncertain parameters of the nuclear winter scenario. Estimates of surface solar radiation reduction range from 20–70% depending on the model and the severity of the soot injection.⁴⁴ Even at 50% reduction, a 300W panel array produces enough energy for HF radio operation — but not with much margin. Larger panels or supplementary power (wind, micro-hydro) would provide resilience.

Vehicle batteries. In an emergency, any 12V vehicle battery can power an HF transceiver directly. NZ has millions of vehicle batteries. As vehicles are mothballed (Doc #6), their batteries become available for other purposes. Lead-acid batteries have finite cycle life (200–500 cycles for automotive, 500–1,500 for deep-cycle)⁴⁵ but NZ can produce replacement lead-acid batteries from recycled lead and sulfuric acid (Doc #35, #116).

Generators. Petrol or diesel generators work but consume irreplaceable fuel. Wood gasifier generators (Doc #56) provide a renewable alternative, though they require more operator attention.

Recommendation for regional nodes: Grid power primary, with a 12V battery bank (minimum 200Ah) and solar panel (minimum 200W) as backup. This ensures the station operates through grid outages and remains functional if the grid degrades in the long term.

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9. TRAINING AND OPERATOR EXPANSION

9.1 The operator shortage problem

Approximately 3,000–4,000 licensed amateur operators is a good starting point but insufficient for a national communication backbone. Not all licensees are active. Not all active operators have HF experience (some operate only VHF/UHF). Not all are located where they are needed. And the amateur population skews older — attrition through death and incapacity will reduce the pool over the coming decades.

Estimate: The network needs a minimum of 200–300 skilled HF operators distributed across the country to maintain a robust regional node structure with adequate depth. NZ probably has this many experienced HF operators now. But the network also needs 1,000+ operators to provide community-level coverage, handle high traffic volumes during crisis periods, and replace attrition. This requires a training program.

9.2 Training pipeline

Phase 1: Immediate activation (Months 0–3). Activate existing AREC-trained operators and all willing amateur licensees with HF capability. NZART branch leaders coordinate local activation. No training required — these operators already have the skills. Focus on organizing them into the network structure described in Section 5.

Phase 1: Accelerated licensing (Months 1–6). NZ’s amateur radio licensing requires passing an examination covering radio theory, regulations, and operating practice.⁴⁶ Under emergency conditions, the examination process can be streamlined: focus on practical operating competence and safety (RF exposure, antenna safety) rather than the full regulatory curriculum. NZART already administers the examination process and could scale it.

Target: 300–500 new operators licensed within the first 6–12 months, depending on the number of experienced operators available as trainers (estimated 10–20 — see below) and the geographic distribution of candidates. The lower end assumes limited trainer availability and candidates concentrated in major centres; the upper end assumes a broader trainer corps and dispersed recruitment. Drawn from:

• Electronics technicians and electrical engineers (existing technical knowledge)
• Military and emergency services personnel (communication discipline)
• Teachers (ability to subsequently train others)
• Young people with technical aptitude (long-term investment)

Phase 2: CW training (Months 3–12). Morse code proficiency takes sustained practice — typically 3–6 months of daily practice to achieve useful operating speed (12–18 words per minute, depending on aptitude and practice intensity). CW training should begin immediately for operators who will staff international link stations, where weak-signal capability matters most. NZART and experienced CW operators can run training nets.

Phase 2–3: Community radio operators (ongoing). Every significant community should have at least one person capable of operating an HF radio for emergency communication. This does not require full amateur licensing — a simplified operator certificate for emergency-only operation, covering basic transceiver operation, antenna management, and message handling, could be developed.

9.3 Training resources

• NZART examination study materials — existing publications cover radio theory and practice⁴⁷
• The ARRL Handbook — comprehensive amateur radio reference, widely available in NZ amateur shacks and libraries (ARRL is the American Radio Relay League, publisher of the standard reference)⁴⁸
• On-air practice — the most effective HF training is operating under guidance from experienced operators. Training nets can be scheduled specifically for new operators.
• Recovery Library Doc #131 (Radio Equipment Fabrication) — for longer-term understanding of radio design and construction

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10. EQUIPMENT INVENTORY AND SUSTAINABILITY

10.1 Current equipment base

NZ’s HF radio equipment base includes:

• Amateur stations: 1,000–2,000 HF-capable amateur stations (estimate based on active licensee numbers). Equipment varies from basic single-band radios to high-end stations with multiple transceivers, amplifiers, and antenna systems. Common brands in NZ amateur use include Yaesu, Icom, and Kenwood — all Japanese manufacturers.⁴⁹ Most modern HF transceivers are solid-state (no vacuum tubes), draw 12–13.8V DC, and include built-in antenna tuners and digital signal processing.

• Marine HF radios: Hundreds of marine HF transceivers aboard NZ fishing vessels, coastal traders, and pleasure craft. These operate on marine HF frequencies but can in many cases be modified or reprogrammed for amateur frequencies. Marine HF equipment is typically robust, designed for harsh salt-water environments.

• Government/military HF: NZDF and government agency HF sets. Numbers and types are not publicly detailed but represent professional-grade equipment with spares support.

• Legacy equipment: Some older amateur operators retain vacuum tube (“valve”) equipment. While outdated by modern standards, valve equipment has an important advantage: vacuum tubes can be manufactured locally (Doc #131) far more readily than semiconductor devices. Valve equipment is also more resistant to EMP (not a primary concern for NZ, but a useful secondary characteristic).

10.2 Equipment lifespan and failure modes

Modern solid-state HF transceivers are generally reliable, with lifespans of 15–30+ years under normal use.⁵⁰ However, they contain components that will eventually fail without imported replacements:

• Electrolytic capacitors: Degrade over time even without use. Typical lifespan 10–25 years depending on quality and temperature. Often the first component to fail in aging electronics.
• Display screens and backlights: LCD displays have limited life (10–20+ years). LED backlights are long-lived. Transceiver functionality is usually unaffected by display failure — the radio still works, though the operator must track frequency manually or by ear.
• Semiconductors (PA transistors, ICs): Generally long-lived if operated within ratings. The power amplifier output transistors are the most stressed components and the most likely to fail.
• Connectors and switches: Mechanical wear and corrosion. Maintainable with cleaning and replacement from salvaged parts.

Estimate: With careful use and competent maintenance, the existing HF transceiver fleet should remain substantially functional for 10–20 years. After that, attrition accelerates. This overlaps with the timeline for locally fabricated radio equipment (Doc #131), which targets simpler designs using locally producible components.

10.3 Stockpiling and preservation

Immediate actions (Phase 1):

• The skills census (Doc #8) should inventory all HF-capable radio equipment in NZ — amateur, marine, commercial, government
• Spare transceivers, components, coaxial cable, connectors, and antenna hardware should be identified and stockpiled at regional nodes
• Equipment from deceased or departed operators should be recovered and redistributed
• Marine HF radios from vessels that are no longer operational should be recovered
• Vacuum tube (valve) equipment and spare tubes should be specifically preserved — these have long-term strategic value

Component salvage priority list:

1. Power amplifier transistors and modules (high failure rate, hard to replace)
2. Coaxial cable and connectors (consumed by antenna installations)
3. Crystal filters and oscillator crystals (precision components, not locally manufacturable)
4. Power supply components (electrolytic capacitors, voltage regulators)
5. Microphones, headphones, Morse keys (wear items)

10.4 Transition to locally fabricated equipment

Doc #131 (Radio Equipment Fabrication) addresses the long-term challenge of building radio transmitters and receivers from NZ materials. The key milestones:

• Phase 2–3: Simple CW (Morse code) transmitters from locally wound coils, NZ-produced capacitors, and salvaged or locally fabricated vacuum tubes. These can be built to produce 5–50W on HF frequencies — sufficient for NZ–Australia communication under favorable conditions. The dependency chain for a locally built CW transmitter includes: copper wire (Doc #70 — requires copper smelting or recycling, wire drawing equipment), capacitors (aluminium foil + paper or mica dielectric — aluminium from recycled stock, mica from NZ deposits if accessible), vacuum tubes (Doc #131 — requires glassblowing capability, vacuum pump, nickel and tungsten for electrodes), and a variable-frequency oscillator (requires precision winding and stable capacitors). Each prerequisite industry takes months to years to establish.
• Phase 3–4: Simple superheterodyne receivers. More complex than transmitters because they require precision intermediate-frequency (IF) filters (crystal or ceramic, likely salvaged), stable local oscillators, and multiple amplification stages. Receiver fabrication depends on a working transmitter program having established the prerequisite component supply chains.
• Phase 4–5: Complete transceiver systems with local materials. Requires all of the above plus transmit-receive switching components and the ability to produce frequency-selective circuits to adequate tolerances.

The transition from commercial to locally fabricated equipment will be gradual, not sudden. Commercial equipment should be maintained as long as possible while local fabrication capability develops. Performance gap: Locally fabricated equipment will be substantially inferior to commercial transceivers. A locally built CW transmitter will likely lack frequency agility (fixed-frequency or narrow-range), produce less clean signals (harmonics and spurious emissions that may interfere with other stations), and require more operator skill to tune and maintain. Locally built receivers will have poorer selectivity (difficulty separating adjacent signals) and higher noise figures (reduced ability to hear weak stations). These are acceptable tradeoffs when the alternative is no equipment at all, but operators should understand that locally fabricated gear requires more skill and patience to use effectively.

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11. INTEGRATION WITH GOVERNMENT COMMUNICATION

11.1 The relationship between amateur and government communication

The amateur radio network described in this document is not a government communication system — it is a national communication resource operated by volunteers, coordinated through NZART, and made available for government use. This distinction matters for both practical and legal reasons.

Practical: Amateur operators are volunteers. They operate best when respected as skilled contributors, not conscripted as government employees. The AREC model — where amateurs work alongside emergency services under a cooperative framework — is the right approach.

Legal: The Radiocommunications Act 1989 and associated regulations govern radio spectrum use in NZ.⁵¹ Under normal circumstances, amateur radio frequencies may not be used for commercial or government traffic. Under the emergency powers of the Civil Defence Emergency Management Act 2002 (or its successor, the Emergency Management Act 2023), the government can authorize use of amateur frequencies for emergency communication.⁵² This authorization should be formalized early.

11.2 Government-amateur coordination framework

Liaison officers. Each regional Civil Defence Emergency Coordination Centre (ECC) should have a designated amateur radio liaison officer — an experienced amateur operator who coordinates between the ECC and the amateur network. AREC already provides this function in exercises and actual emergencies, though not all ECCs have active AREC representation.

Traffic priorities. Government traffic (official messages between government agencies, international diplomatic communication) should receive priority on the network but should not monopolize it. The radiogram precedence system (Section 5.4) handles this — government traffic is filed as “priority” or “emergency” precedence; welfare messages (personal inquiries about family, etc.) as “welfare”; routine traffic as “routine.”

Security. HF radio is not secure — anyone with a receiver can listen. Government communication that requires confidentiality should use pre-arranged code systems for sensitive content. One-time pad encryption is achievable but labour-intensive. For most government communication in this scenario, the content is not sensitive — it is logistical coordination, not military intelligence. Plain-language communication should be the default.

11.3 Integration with public communication (Doc #2)

HF radio can serve as a government broadcast channel if conventional broadcast infrastructure degrades in specific regions. A scheduled government information broadcast on an agreed HF frequency, received by amateur operators in each community who then disseminate the information locally, provides a communication pathway that is independent of the broadcast network. This is a contingency — not the expected primary broadcast channel — but it should be planned for.

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12. MARITIME HF AND SAILING VESSEL COMMUNICATION

12.1 Maritime HF infrastructure

NZ has an existing maritime HF communication infrastructure, though it has contracted as satellite communication became dominant for maritime use. Maritime HF operates on designated marine bands (principally around 4, 6, 8, 12, 16, and 22 MHz) and is governed by maritime radio regulations.⁵³

As NZ develops a sailing vessel trade fleet (Doc #138, #141, #143, #144), HF radio becomes the primary communication system for vessels at sea. Satellite communication systems (Inmarsat, Iridium) depend on satellite constellation maintenance that will not continue indefinitely without ground infrastructure support — their operational lifespan is uncertain but likely years to a decade or two at most.⁵⁴

12.2 Vessel HF requirements

Every ocean-going vessel should carry:

• An HF transceiver capable of operation on both marine and amateur frequencies (many marine HF radios can be retuned; alternatively, carry an amateur HF transceiver alongside the marine set)
• An effective HF antenna (a backstay antenna or dedicated HF whip is standard on sailing vessels)
• Backup power (vessel batteries, charged from solar panels, wind generator, or towed generator)
• At least one crew member trained in HF operation and message handling

12.3 Maritime nets

A maritime HF net — daily scheduled check-ins for all vessels at sea — provides:

• Position reporting and tracking
• Weather information exchange
• Emergency coordination (distress relay)
• Traffic handling (messages to and from shore)

NZ amateur radio already has a tradition of maritime nets supporting offshore sailing vessels. This existing practice scales naturally to support the trade fleet.

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13. REMOTE COMMUNITY COVERAGE

Several NZ communities are geographically isolated and depend on limited telecommunications links:

• Chatham Islands (approximately 800 km east of Christchurch)
• Stewart Island / Rakiura
• West Coast communities (limited road links, vulnerable to landslides)
• Remote East Coast communities
• Outer islands (Kermadecs — if inhabited for monitoring purposes)

These communities should be prioritized for HF station establishment. For the Chatham Islands in particular, HF radio may become the primary communication link if submarine cable or satellite connections are lost.

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14. CRITICAL UNCERTAINTIES

Uncertainty	Why It Matters	How to Resolve	Impact if Adverse
Ionospheric propagation after nuclear exchange	Determines when HF communication is possible and on which bands	Empirical monitoring from Day 1; log all propagation conditions	If severe disruption persists for weeks, initial international contact is delayed; domestic NVIS on lower bands likely recovers faster
Actual number of active HF-capable amateur operators	Determines how quickly the network can be activated	Skills census (Doc #8); NZART activation survey	If far fewer than estimated, network activation is slower; regional coverage gaps emerge
State of submarine cable connections to Australia	Determines whether HF is the primary or backup international channel	Test cable connectivity from Day 1	If cables are down, HF becomes the primary international link — higher traffic load, more stations needed on international duty
Solar radiation reduction under nuclear winter	Affects solar-powered station viability	Measure actual solar irradiance; compare panel output pre- and post-event	If solar output drops >50%, off-grid stations need larger panel arrays or alternative power
Equipment lifespan without imported spares	Determines when transition to locally fabricated equipment is needed	Track failure rates across the transceiver fleet; maintain failure database	If transceiver failure rate is faster than expected, Doc #131 timeline must accelerate
Australian amateur radio community survival and organization	Determines the robustness of the trans-Tasman communication link	Establish contact and assess within first 48 hours	If Australian amateur community is disrupted (unlikely given Australia’s distance from targets, but possible through secondary effects), NZ must establish contact through other means
Nuclear winter effects on ionosphere	May alter propagation patterns unpredictably	Systematic propagation monitoring and comparison with pre-war baselines	If MUF drops significantly, higher bands become unusable; network shifts to lower frequencies with reduced bandwidth
Government HF capability (actual current state)	Determines how much government communication must rely on amateur network	Audit through NZDF and emergency management agencies	If government HF is minimal, amateur network carries higher government traffic load

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15. CROSS-REFERENCES

Document	Relevance to This Document
Doc #1 — National Emergency Stockpile Strategy	Framework for requisitioning and managing radio equipment stocks
Doc #2 — Public Communication	HF radio as contingency broadcast channel if conventional media degrades
Doc #156 — Skills Census	Inventory of radio equipment and operator skills
Doc #135 — Computer Construction	Long-term computing for network scheduling and propagation prediction
Doc #35 — Battery Management and Lead-Acid Production	Power supply for off-grid HF stations
Doc #56 — Wood Gasification	Generator fuel for HF stations without grid or solar power
Doc #65 — Hydroelectric Maintenance	Grid power continuity — the baseline for most HF station power
Doc #70 — Copper Wire Production	Antenna wire production for long-term sustainability
Doc #73 — Solar Panel and Inverter Maintenance	Solar power for off-grid stations
Doc #91 — Machine Shop Operations	Fabrication of antenna hardware, mast fittings, connectors
Doc #98 — Glass Production	Insulators for antenna construction
Doc #127 — NZ Telecommunications Maintenance	Complementary document on conventional telecom sustainability
Doc #131 — Radio Equipment Fabrication	Long-term replacement of imported radio equipment
Doc #138 — Sailing Vessel Design	Maritime HF communication requirements
Doc #139 — Celestial Navigation	Maritime operations that HF communication supports
Doc #141 — Trans-Tasman and Pacific Trade Routes	Trade routes that HF communication enables
Doc #151 — NZ-Australia Relations Relations	Diplomatic communication via HF
Doc #152 — International Relations: Wider World	International contact via HF
Doc #160 — Heritage Skills Preservation	Older operators hold CW and valve-equipment knowledge

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16. WHAT THIS DOCUMENT DOES NOT COVER

• Detailed radio construction instructions — See Doc #131 (Radio Equipment Fabrication) for building transmitters and receivers from NZ materials.
• VHF/UHF repeater network maintenance — Related but distinct from HF; the repeater network is infrastructure-dependent and follows a different degradation trajectory.
• Satellite communication — Existing satellite systems (Inmarsat, Iridium, Starlink) may remain partially functional for years but depend on constellation maintenance that is unlikely to continue indefinitely. A separate assessment of satellite communication lifespan would be valuable but is outside this document’s scope.
• Broadcast radio and television — Covered under Doc #2 (Public Communication) and the baseline assumption of continued broadcast infrastructure.
• Encryption and secure communications — Government communication security is a distinct topic requiring its own analysis.

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APPENDIX A: QUICK-START GUIDE FOR EXISTING AMATEUR OPERATORS

If you are a licensed NZ amateur radio operator reading this document after the event:

1. Check in on your local NZART branch net on the usual frequency at the usual time. If no net is active, try 3.600 MHz LSB at 0800 NZST or 7.090 MHz LSB at 1900 NZST.
2. Monitor 14.300 MHz USB for international emergency traffic.
3. Attempt contact with Australian stations on 14.295 MHz USB (daytime) or 7.095 MHz LSB (evening).
4. Log all contacts and propagation conditions — signal reports, noise levels, band conditions. This data is important.
5. Contact your nearest Civil Defence office and offer your services.
6. Ensure your station has backup power — at minimum, a charged 12V battery.
7. Pass this information to any amateur operators you contact.

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APPENDIX B: QUICK-START GUIDE FOR NON-AMATEUR READERS

If you are a government official, Civil Defence coordinator, or community leader with no amateur radio background:

1. Find your nearest amateur radio operator. NZART branch lists, local knowledge, or the skills census (Doc #8) will identify them. In most NZ communities of 1,000+ people, there is likely at least one licensed amateur, though this estimate is based on the national ratio of approximately 3,000–4,000 licensees across a population of 5.2 million and does not account for geographic clustering in urban areas.⁵⁵
2. Amateur radio operators can communicate internationally using equipment they already own. They do not need any additional infrastructure, internet connectivity, or government equipment.
3. The most useful thing you can do is provide the amateur radio community with organizational support: designated meeting space, inclusion in Civil Defence planning, priority access to battery and solar panel stocks, and recognition of their contribution.
4. Do not attempt to commandeer amateur radio equipment or operators. Cooperation produces far better results than coercion. These are skilled volunteers.
5. Message handling works. If you need to send a message to another region or another country, give it to an amateur operator in radiogram format (Section 5.4). It will be relayed through the network.

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APPENDIX C: NZ HF PROPAGATION QUICK REFERENCE

Approximate band-opening times for major paths from NZ. These are pre-event baselines — post-event conditions may differ significantly.

Path	Distance (km)	Best Daytime Band	Best Nighttime Band	Typical MUF Range
NZ domestic (NVIS)	0–600	40m (7 MHz)	80m (3.5 MHz)	5–10 MHz
NZ–Australia	2,000–3,000	20m (14 MHz)	40m (7 MHz)	8–25 MHz
NZ–Pacific Islands	1,500–4,000	20m (14 MHz)	40m (7 MHz)	10–28 MHz
NZ–South America	9,000–11,000	15m/20m (14–21 MHz)	20m (14 MHz)	10–25 MHz
NZ–Southern Africa	11,000–12,000	15m/20m (14–21 MHz)	20m (14 MHz)	10–25 MHz
NZ–Antarctica	2,500–5,000	20m (14 MHz)	40m (7 MHz)	5–20 MHz

Note: MUF values are rough ranges reflecting seasonal and solar cycle variation. During solar minimum, higher bands (15m, 10m) may be unusable for long-distance paths. During solar maximum, these bands open regularly. Post-event ionospheric conditions add additional uncertainty.

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1. Ionospheric propagation of HF radio waves is well-established physics. See Davies, K. (1990), Ionospheric Radio, Peter Peregrinus Ltd.; or any amateur radio reference such as the ARRL Handbook.↩︎

2. NZ’s international submarine cable connections include the Southern Cross Cable Network (NZ–Australia–United States) and the Hawaiki Cable (NZ–Australia–United States). See https://www.submarinecablemap.com/ for current cable routes.↩︎

3. NZ domestic telecommunications infrastructure is described in Commerce Commission Telecommunications Monitoring Reports. See https://comcom.govt.nz/regulated-industries/telecommunica... Cell tower battery backup duration is typically 4–8 hours per industry standards, though some sites have longer backup.↩︎

4. NZART history and organizational information: https://www.nzart.org.nz/about/. NZART was founded in 1926 and has been the national amateur radio organization since.↩︎

5. NZ amateur radio operator numbers are maintained by Radio Spectrum Management (RSM), MBIE. The figure of 3,000–4,000 is an estimate based on publicly available licensing data and NZART membership figures. The exact number of current licensees requires verification from RSM. Not all licensees are NZART members, and not all are active.↩︎

6. NZ amateur radio licensing classes and requirements are administered by RSM under the Radiocommunications Regulations. See https://www.rsm.govt.nz/licensing/amateur-radio/. General Amateur Operator licence permits operation on all amateur bands up to 1 kW PEP.↩︎

7. NZART branch structure: https://www.nzart.org.nz/branches/. Approximately 80 branches cover NZ from Northland to Southland.↩︎

8. AREC information: https://www.nzart.org.nz/activities/arec/. AREC is the emergency communication service of NZART, providing amateur radio communication support during emergencies.↩︎

9. The National Emergency Management Agency (NEMA) coordinates national emergency management in NZ, replacing the former Ministry of Civil Defence and Emergency Management (MCDEM) in 2019. See https://www.civildefence.govt.nz/.↩︎

10. AREC deployment in Christchurch earthquakes, Kaikōura earthquake, and Cyclone Gabrielle is documented in NZART annual reports and AREC after-action reports. Amateur radio provided backup communication when commercial networks were overloaded or damaged.↩︎

11. Maritime NZ administers maritime radio communication. See https://www.maritimenz.govt.nz/. Maritime HF frequencies are allocated internationally through the ITU Radio Regulations.↩︎

12. NZ coast radio stations ZLM (Taupo) and ZLD (Auckland) provided HF maritime communication services. Some coast station HF services have been discontinued as satellite communication became dominant. The current status of NZ coast station HF capability requires verification.↩︎

13. NZDF radio communications capability is not publicly detailed but NZDF operates HF radio for military communication as standard practice. RNZN vessels carry naval HF systems.↩︎

14. Chatham Islands communication has historically depended on HF radio and, more recently, satellite and submarine cable links. The Chathams’ geographic isolation makes HF communication particularly important as a backup.↩︎

15. NZART repeater directory: https://www.nzart.org.nz/activities/repeaters/. The repeater network provides VHF/UHF coverage across most populated areas of NZ.↩︎

16. Ionospheric physics and HF propagation: Davies, K. (1990), Ionospheric Radio; McNamara, L.F. (1991), The Ionosphere: Communications, Surveillance, and Direction Finding. Standard references.↩︎

17. Maximum Usable Frequency (MUF) prediction is a well-established practice. Real-time MUF data was available pre-event from various online sources. Post-event, MUF must be determined empirically by monitoring beacon stations and logging propagation conditions.↩︎

18. Trans-Tasman HF propagation characteristics are well-known to NZ and Australian amateur operators. The path characteristics described are based on standard amateur radio operating experience for this path.↩︎

19. The 40m band as a trans-Tasman workhorse is a widely shared observation in the NZ and Australian amateur radio communities. See VK/ZL operating guides in the ARRL Handbook or Australian WIA publications.↩︎

20. Great-circle distances from NZ: Chile (Santiago) approximately 9,600 km, Argentina (Buenos Aires) approximately 10,400 km. Calculated from standard geographic coordinates.↩︎

21. South African Radio League (SARL): https://www.sarl.org.za/. South Africa has one of the largest amateur radio communities in the Southern Hemisphere.↩︎

22. Great-circle distances from Wellington: London approximately 18,900 km, Tokyo approximately 9,500 km. Calculated from standard geographic coordinates (Wellington 41.3°S 174.8°E, London 51.5°N 0.1°W, Tokyo 35.7°N 139.7°E).↩︎

23. Near-Vertical Incidence Skywave (NVIS) propagation: Fiedler, D.M. and Farmer, E.J. (1996), Near Vertical Incidence Skywave Communication. NVIS provides reliable short- to medium-distance HF coverage (0–500 km) using horizontally polarized antennas at low height.↩︎

24. EMP effects from nuclear detonations: Glasstone, S. and Dolan, P.J. (1977), The Effects of Nuclear Weapons, US Department of Defense. EMP is primarily a line-of-sight effect; the E1 component (fast pulse) is the most damaging to electronics and has limited range from the detonation point.↩︎

25. Starfish Prime (1962) ionospheric effects: Dyal, P. (2006), “Nuclear Explosions in Orbit,” Science and Global Security, 14:1, 1–28. HF blackout duration varied from hours to days depending on frequency and path.↩︎

26. Hemispheric confinement of charged particles by the geomagnetic field is well-established in space physics. Cross-equatorial transport occurs but is limited compared to within-hemisphere transport. The degree of ionospheric coupling between hemispheres during a massive nuclear exchange is not precisely known.↩︎

27. Nuclear winter ionospheric effects are inherently uncertain due to the lack of direct precedent. Existing models (Turco et al., 1983; Robock et al., 2007) focus primarily on surface climate rather than ionospheric effects. The ionospheric impact is an extrapolation.↩︎

28. Reduced solar UV reaching the ionosphere due to stratospheric soot would reduce ionospheric electron density and lower the MUF. This follows directly from the physics of ionospheric formation (solar UV is the primary ionization source), but the quantitative effect depends on the magnitude and duration of soot injection. See Robock, A. et al. (2007), “Nuclear winter revisited with a modern climate model,” Journal of Geophysical Research, 112, D13107.↩︎

29. NZ amateur radio band allocations are specified by RSM. See https://www.rsm.govt.nz/. NZ allocations follow IARU Region 3 band plans with NZ-specific variations.↩︎

30. 14.300 MHz USB is the internationally recognized centre of activity for emergency and disaster communication on the 20m amateur band. This convention is maintained by the IARU.↩︎

31. Wireless Institute of Australia (WIA): https://www.wia.org.au/. WIA is the Australian equivalent of NZART and the coordination point for any bilateral emergency communication arrangements.↩︎

32. JS8Call: Jordan Sherer (KN4CRD), JS8Call software. See http://js8call.com/. JS8Call is a keyboard-to-keyboard digital mode built on WSJT-X FT8 encoding, designed for weak-signal HF message relay.↩︎

33. Winlink Global Radio Email: https://www.winlink.org/. Winlink supports HF email via amateur radio, including peer-to-peer mode without internet connectivity.↩︎

34. The radiogram message format is standardized by the ARRL National Traffic System (NTS). The same format is widely used internationally, including in NZ amateur radio practice. See ARRL Operating Manual for detailed traffic handling procedures.↩︎

35. WIA membership and Australian amateur radio statistics: https://www.wia.org.au/. The figure of 15,000–16,000 licensed Australian amateurs is approximate and based on publicly available ACMA licensing data.↩︎

36. The primacy of antennas over transmitter power in HF station effectiveness is a fundamental principle of radio engineering. A 3 dB improvement in antenna gain is equivalent to doubling transmitter power. See any antenna engineering reference, e.g., Balanis, C.A. (2016), Antenna Theory: Analysis and Design, Wiley.↩︎

37. Dipole antenna theory and construction: standard reference in any amateur radio handbook. The half-wave dipole is the fundamental reference antenna for HF work.↩︎

38. Long wire antenna characteristics and use with antenna tuners: see ARRL Antenna Book or equivalent reference. Most modern HF transceivers include built-in antenna tuners capable of matching a wide range of antenna impedances.↩︎

39. Near-Vertical Incidence Skywave (NVIS) propagation: Fiedler, D.M. and Farmer, E.J. (1996), Near Vertical Incidence Skywave Communication. NVIS provides reliable short- to medium-distance HF coverage (0–500 km) using horizontally polarized antennas at low height.↩︎

40. Steel wire resistivity is approximately 10 times that of copper (steel ~1.0 x 10^-7 ohm-m vs copper ~1.7 x 10^-8 ohm-m). The actual RF loss increase at HF frequencies depends on skin effect, wire gauge, and frequency. Galvanized steel has somewhat better surface conductivity due to the zinc coating but the loss penalty remains substantial. See Balanis, C.A. (2016), Antenna Theory, or ARRL Antenna Book for detailed conductor loss calculations.↩︎

41. Open-wire (ladder line) feedline has lower loss than coaxial cable at HF frequencies, particularly when used with high standing wave ratios. This was the standard feedline before coax became common in the mid-20th century. Construction requires two parallel conductors separated by periodic spacers at consistent spacing, with attention to impedance maintenance near structures.↩︎

42. Typical HF transceiver power consumption figures: based on specifications of common amateur HF transceivers (Yaesu FT-991A, Icom IC-7300, Kenwood TS-590SG — representative models widely used in NZ). Transmit current at 100W is typically 20–23A at 13.8V DC; receive current is 1–2A.↩︎

43. NZ solar irradiance data: NIWA National Climate Database. NZ receives approximately 3–5 peak sun hours per day averaged annually, varying by region (Northland/Nelson highest, Southland lowest) and season.↩︎

44. Solar radiation reduction under nuclear winter scenarios: Robock, A. et al. (2007), “Nuclear winter revisited,” estimates surface solar radiation reduction of 20–70% depending on scenario severity, geographic location, and time since exchange. The wide range reflects genuine uncertainty in soot injection quantities and atmospheric transport models.↩︎

45. Lead-acid battery cycle life: general battery engineering data. Automotive batteries: 200–500 cycles typical. Deep-cycle batteries: 500–1,500 cycles depending on depth of discharge and construction quality.↩︎

46. NZ amateur radio licensing classes and requirements are administered by RSM under the Radiocommunications Regulations. See https://www.rsm.govt.nz/licensing/amateur-radio/. General Amateur Operator licence permits operation on all amateur bands up to 1 kW PEP.↩︎

47. NZART examination resources: https://www.nzart.org.nz/exam/. NZART provides study guides and administers examinations for amateur radio licensing in NZ.↩︎

48. ARRL Handbook for Radio Communications, published annually by the American Radio Relay League. The standard comprehensive reference for amateur radio theory and practice. Widely available in NZ amateur radio stations and public libraries.↩︎

49. Yaesu, Icom, and Kenwood are the three major manufacturers of amateur HF radio equipment globally. All are Japanese companies. Their products dominate the NZ amateur radio market. Based on general knowledge of the NZ amateur radio market.↩︎

50. HF transceiver lifespan estimate: based on observed longevity of solid-state amateur radio equipment. Many transceivers from the 1990s and 2000s remain in active use. Electrolytic capacitor aging is typically the primary failure mode in aging electronics. The 15–30+ year range is an estimate; actual lifespan varies with usage, environment, and construction quality.↩︎

51. Radiocommunications Act 1989: NZ legislation governing radio spectrum management. See https://www.legislation.govt.nz/act/public/1989/0148/.↩︎

52. Emergency management legislation authorizing emergency use of radio spectrum: Civil Defence Emergency Management Act 2002 and Emergency Management Act 2023. These acts provide for emergency powers including direction of resources and services during declared emergencies.↩︎

53. Maritime radio regulations: International Telecommunication Union (ITU) Radio Regulations, Chapter VII (Maritime mobile service). Implemented in NZ through Maritime Transport Act and associated regulations.↩︎

54. Satellite communication system lifespan: Inmarsat and Iridium satellites have designed lifespans of 10–15+ years, but constellation maintenance (replacement launches, ground station operation, software updates) requires global industrial capability. Without replacement launches, constellations degrade as individual satellites fail. Iridium NEXT constellation was completed in 2019; without replacement, coverage would degrade over 10–15 years. Starlink satellites have shorter individual lifespans (approximately 5 years) and require frequent replacement launches.↩︎

55. NZ population approximately 5.2 million (Stats NZ, 2024). With 3,000–4,000 amateur licensees, the average ratio is approximately 1 licensee per 1,300–1,700 people. However, amateur radio demographics skew toward urban areas and older age brackets, so rural communities of 1,000 people may have no licensee. The skills census (Doc #8) would establish the actual distribution.↩︎