HF radio is the only infrastructure-independent technology that allows a prepared citizen to communicate over hundreds or thousands of miles without relying on cell towers, internet, repeaters, or satellites. When infrastructure fails — whether from natural disaster, grid collapse, or deliberate disruption — HF remains operational because it exploits a physical phenomenon no government or corporation controls: the ionosphere. For any serious PACE plan that includes a long-range contingency, HF is the answer.
How HF Works: Skywave Propagation
High-frequency radio occupies the 3–30 MHz band and behaves fundamentally differently from the VHF and UHF frequencies used by handheld radios. VHF/UHF signals travel in line-of-sight paths and are blocked by terrain, buildings, and the curvature of the Earth, practically limiting them to a few miles without repeaters. HF energy, by contrast, can be directed upward at an appropriate angle where it refracts off the ionosphere — the electrically charged upper atmosphere — and returns to Earth at great distance. This phenomenon, called skywave or skip propagation, allows HF stations running modest power to reach targets hundreds or thousands of miles away.
Propagation quality varies with time of day, season, and solar conditions. Bands like 40 meters (7 MHz) and 80 meters (3.5 MHz) are particularly effective at night, when the ionosphere’s lower D-layer dissipates and signals skip more efficiently. The 20-meter band (14 MHz) is a workhorse daytime band for intercontinental contacts. Understanding these patterns — and building flexibility into scheduled communications — is part of what separates a functional HF operator from someone who owns an HF radio but can’t make contact when it matters.
The trade-off is bandwidth. The same long wavelengths that enable skip propagation carry limited data. HF is fundamentally a voice and low-bandwidth digital medium, not a replacement for broadband. At the extreme, the physics become stark: the U.S. Navy’s ELF (extremely low frequency) stations could penetrate 300 feet of seawater to reach submarines, but transmitted only about one character every several minutes with multi-megawatt transmitters and antennas stretching 80 miles. HF is vastly more practical, but it remains a narrow pipe compared to modern digital infrastructure — which is fine, because the goal is reliable contact, not streaming video.
Practical HF: Equipment and Architecture
Entry-level HF is more affordable than many assume. The Xiegu G90 is a capable conventional HF transceiver with an internal SDR and waterfall display, operating at up to 100 watts, available for roughly $500. It was used in a demonstrated 1,500-mile contact exercise from Nashville, Tennessee to outside Phoenix, Arizona. However, the preferred architecture for HF operations is shifting toward simple RF hardware boxes with a USB interface — a small radio handling only RF transmission and reception, with a connected computer or Raspberry Pi handling all signal processing and digital mode operation.
The QRP Labs QDX exemplifies this approach: a compact box with antenna, power, and USB connections, running at 5 watts, controllable entirely by software. This architecture is superior because it allows the operator to run any digital mode the community develops — JS8Call, FT8, Winlink, or future protocols — without waiting for radio firmware updates or dealing with proprietary interfaces. At 5 watts with a good digital mode and a resonant antenna, transoceanic text communication is achievable.
Connecting a phone or computer to a conventional HF radio like the Xiegu G90 currently requires multiple adapters and breakout boards. The Digirig adapter partially addresses this gap, but the long-term trend is toward purpose-built computer-controlled radios.
A 20-watt HF mobile radio paired with a simple wire antenna deployed in a tree can realistically cover most of the United States and portions of Europe. Field antenna deployment is a skill unto itself — the antenna is arguably more important than the radio, and poor antenna work will cripple even the best transceiver. The Radio Operator and Antenna Handbooks cover HF-specific antenna considerations, including wire dipoles, end-fed half-waves, and vertical antenna configurations with ground radial systems.
Grounding: The Most Common HF Failure Point
Improper grounding is the most common cause of weak HF signals and can reduce communication distances by 50 percent or more. It also creates serious electrical hazards. Ground stakes must be driven deeply into soil with tight, clean connections. Soil moisture and salinity are critical — damp locations dramatically outperform dry ground, and adding salt or water around stakes improves conductivity.
Vertical HF antennas require a ground radial system (counterpoise) to reduce power loss in the earth and establish a known electrical reference point. For optimal performance, at least 30 radials spaced 12 degrees apart are recommended, with radial length calculated based on operating frequency. Semipermanent installations benefit from 100 radials at doubled length. For a field-expedient setup, even a few radials laid on the ground will meaningfully improve performance over no counterpoise at all. These details are covered in depth in the field antenna installation material.
Digital Modes: JS8Call and the Future of HF
Analog voice over HF works but is highly susceptible to interference, band congestion, and noise. During the 1,500-mile Nashville-to-Phoenix exercise, voice attempts on both primary and contingency frequencies failed entirely. The JS8Call digital mode, however, succeeded — highlighting the superior noise rejection and low-power efficiency of digital modes over analog voice at range.
JS8Call is a keyboard-to-keyboard text communication mode optimized for HF. It operates on extremely narrow bandwidth, tolerates noise that would render voice unintelligible, and supports mesh-forwarding — messages can hop through intermediate stations to reach their destination, creating a rudimentary mesh network across states. It is the preferred digital protocol for organized HF preparedness networks. S2 Underground’s Ghost Net operates entirely using JS8Call as a large organized HF chat group. The ability to send targeted text messages over HF with high reliability at very low power makes JS8Call the most practical digital mode for emergency preparedness applications.
Morse code shares many of the same advantages — narrow bandwidth and excellent intelligibility through noise — but requires dedicated operator training. Both Morse and JS8Call dramatically outperform voice for getting a message through under adverse conditions.
Licensing and Operator Investment
HF operation requires an FCC Amateur Radio license at the General class or higher for full HF transmit privileges. The Technician-class license grants only limited HF access. This is a meaningful barrier, but a General license is achievable with focused self-study. The knowledge gained in the licensing process — propagation theory, antenna design, electrical safety, operating procedures — is directly useful. See radio licensing for a broader discussion.
Beyond licensing, HF demands more operator skill than VHF/UHF. Band selection, propagation prediction, antenna deployment, grounding, digital mode configuration, and timing synchronization are all learned skills. This is not plug-and-play gear. The investment in training pays dividends in capability that no amount of equipment spending can substitute — a principle that applies across the entire prepared citizen’s toolkit, as discussed in Training as a Duty.
Operational Discipline: Structured Communication Plans
The 1,500-mile exercise demonstrated that HF communication requires operational discipline, not just equipment. A structured communications plan was used with specific frequencies, designated time windows, and contingency bands (20m primary, 17m alternate). This mirrors real emergency communication discipline and aligns directly with PACE framework methodology — primary, alternate, contingency, and emergency means of making contact.
Timing synchronization is critical for scheduled HF contacts. GPS watches, the Fort Collins time-signal stations (WWV on 5, 10, 15, and 20 MHz), and JS8Call’s own timing-sync capability are all viable methods. A good watch is a communications tool; see why every prepared person should wear one.
Authentication is equally important. Pre-arranged one-time pad tables verify that a received message genuinely originates from the intended party and not an impersonator. This is a basic signal security measure that costs nothing but forethought.
HF in the Bigger Picture
HF fills a specific and irreplaceable role in the civilian communicator’s layered plan. UHF radios handle local tactical communication out to a few miles. Mesh networking devices like Meshtastic extend range and add digital capability at the local and regional level. But when the requirement is coast-to-coast or even intercontinental contact with zero infrastructure dependency, HF is the only option available to a private citizen.
This capability matters most precisely when everything else has failed. A regional disaster that takes down cell networks and internet may leave local repeaters intact — but a national-scale disruption, a prolonged grid failure, or a situation where repeater infrastructure has been deliberately targeted eliminates every communication layer except HF and satellite. Satellite systems, while valuable, depend on corporate infrastructure and subscription services that may not survive the same disruptions that took down terrestrial networks. HF depends on the ionosphere, copper wire, and operator skill — nothing more.
The practical implication is that any group serious about preparedness beyond the local level needs at least one trained HF operator with deployable equipment. This does not mean every member of a prepared community needs a General-class license and a transceiver. It means the community needs to invest in developing that capability deliberately — identifying someone willing to pursue the licensing and training, funding equipment acquisition, and integrating HF into regular communication exercises. A single competent HF station with a wire antenna, a QDX or similar digital transceiver, and a laptop running JS8Call can connect a local group to a nationwide network of like-minded operators.
The technology is mature, the equipment is affordable, the physics are permanent, and the licensing path is straightforward. The only variable is whether individuals and communities choose to invest the time to develop the skill. Like every other capability discussed across this wiki, the gap between owning the gear and being able to employ it effectively under pressure is bridged exclusively by training and practice.