Amateur radio propagation beacon

Lore & Background

Most propagation beacons transmit in continuous wave (A1A) with their call sign and location; some send long dashes for signal strength measurement. A small number use frequency-shift keying (F1A) for Morse code, and a few employ digital modes like radioteletype (F1B) and PSK31 (G1B). In the United States, unattended beacons on frequencies below the 10-meter band (~28 MHz) are not legal.

Beacons are found on many bands. On 2200 meters (135.7–137.8 kHz), amateur experiments often involve temporary beacons. In the US and Canada, unlicensed LowFERs operate low-power beacons between 160 and 190 kHz. The IARU Region 2 bandplan for 160 meters reserves 1999–2000 kHz for propagation beacons. Most HF beacons are on 10 meters (28 MHz), where they indicate Sporadic E propagation. On 6 meters (50 MHz), beacons traditionally operate in 50.000–50.080 MHz; IARU Region 1 encourages moving to 50.4–50.5 MHz, while the FCC permits unattended 6-meter beacons only between 50.060 and 50.080 MHz.

On 4 meters (70 MHz), several ITU Region 1 countries have access; the preferred beacon location is 70.000–70.090 MHz. In the US, Brian Justin, WA1ZMS, obtained an experimental license for a 4-meter beacon, WE9XFT, on 70.005 MHz transmitting 3 kW ERP from Apple Orchard Mountain, Virginia. VHF/UHF beacons on 144 MHz and above identify tropospheric openings and often use directional antennas. Microwave beacons are also used to test and calibrate antennas and receivers; beacons above 10 GHz are unusual.

Reader's Guide

Amateur radio propagation beacons serve as essential tools for understanding and exploiting radio wave propagation. They provide real-time indicators of band openings, particularly on bands like 6 meters where propagation is unpredictable and intermittent. The IARU Beacon Project, coordinated with the Northern California DX Foundation, operates 18 HF beacons worldwide that transmit in turn on five frequencies, enabling operators to assess propagation paths globally. The DARC Beacon Project in Germany transmits solar and geomagnetic bulletins every 10 minutes, aiding in space weather awareness. The RSGB's GB3ORK in the Orkney Islands and the GB3RAL cluster at the Rutherford Appleton Laboratory offer continuous signals for propagation monitoring.

Large-scale projects like the WSPRnet use the WSPR transmission scheme to collect and display real-time propagation data via the Internet, creating detailed maps and databases. The Synchronized Beacon Project coordinates 50 MHz beacons using a one-minute sequence of PI4, CW, and unmodulated carrier. High-power beacons, such as KR4GPI on 2 meters (413W ERP) and its 10-meter RTTY beacon (1.9 kW ERP), provide regional coverage for propagation research and band openings. These beacons also assist Parks on the Air and Summits on the Air activators in determining viable communication paths. The legacy of these beacons is their role in advancing radio science, enabling amateur and academic researchers to study ionospheric and tropospheric propagation continuously.

Did You Know?

• The International Beacon Project consists of 18 HF propagation beacons worldwide transmitting on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz.
• The WE9XFT 4-meter beacon in Virginia transmits 3 kW ERP on 70.005 MHz under a non-amateur experimental license.
• The KR4GPI 2M beacon is the most powerful east of the Mississippi River, at 70W PEP and 413W ERP.