Radio Frequencies and Field Communication

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Radio · Reference

Before you begin

The band, antenna, geography, power and licence rules determine whether a radio can reach another person. Frequency charts are reference points, not permission to transmit.

Safety and legality: Do not transmit on aviation, marine, rescue or other protected frequencies without authority and a genuine legal basis. Regulations and channel allocations vary by jurisdiction.

A quick orientation to HF (3–30 MHz), VHF (30–300 MHz) and UHF (300–3000 MHz), with a few widely recognized services.

Six practical skills

1Identify the radio band 2Know critical frequencies 3Recognize common non-emergency services 4Match antenna, distance and conditions 5Separate receiving from transmitting 6Prepare an emergency plan

Field skill 1 / 6

Identify the radio band

HF spans 3–30 MHz and can support long-range contacts when propagation cooperates. VHF spans 30–300 MHz and is often line of sight. UHF spans 300–3000 MHz and is commonly used for local handheld communication and data.

Field skill 2 / 6

Know critical frequencies

121.5 MHz is an international civil aviation distress frequency; 156.8 MHz is marine VHF channel 16; registered 406 MHz distress beacons serve satellite alerting systems. These are safety channels, not places to test homemade equipment.

Field skill 3 / 6

Recognize common non-emergency services

Broadcast FM radio occupies 87.5–108 MHz in many countries; marine AIS normally broadcasts on 161.975/162.025 MHz; ADS-B aircraft data often uses 1090 MHz. European PMR446 operates in the 446 MHz band with compliant equipment and applicable national rules.

Field skill 4 / 6

Match antenna, distance and conditions

Antenna placement, polarization, terrain, atmospheric conditions and cable losses can dominate performance. Even a powerful transmitter cannot guarantee reception behind a mountain. Check batteries and line-of-sight paths before relying on equipment.

Field skill 5 / 6

Separate receiving from transmitting

Receiving permissible public transmissions with a suitable receiver is distinct from transmitting. For two-way radios use certified equipment and appropriate licensing or licence-exempt allocations for the exact country. Amateur-radio privileges are not universal.

Field skill 6 / 6

Prepare an emergency plan

Keep a battery-powered broadcast receiver and written contact schedule, call signs when legally assigned, emergency channels, family meeting points, backup charging and a shared message format. Do not block a distress frequency with routine traffic.

Reference frequency examples

Frequencies below are illustrations of common services, not a licence to transmit. Country-specific channel plans and conditions of use still apply.

Frequency	Service	Notes
3–30 MHz	HF band	Shortwave propagation depends on conditions.
87.5–108 MHz	Broadcast FM	Region-dependent allocations.
121.5 MHz	Aviation distress	Protected emergency frequency.
156.8 MHz	Marine VHF channel 16	Distress, safety and calling where applicable.
161.975 / 162.025 MHz	Marine AIS 1 / AIS 2	Public vessel identification data broadcasts.
446 MHz band	PMR446 (Europe)	Compliant handhelds; local rules apply.
978 MHz	UAT ADS-B (US)	Regional aircraft data link.
1090 MHz	Mode S / ADS-B	Aircraft data broadcasts.

Related guides

Reference sources

Verify local laws and manufacturer guidance before field use. Information reviewed November 2026.