According to IARU bandplans, the following 28 MHz frequencies are allocated to radio propagation beacons: Due to unpredictable and intermittent long-distance propagation, usually achieved by a combination of ionospheric conditions, beacons are very important in providing early warning for 6-meter band (50 MHz) openings.
[4][5] In the United States, the Federal Communications Commission (FCC) only permits unattended 6-meter beacon stations to operate between 50.060 and 50.080 MHz.
Brian Justin, WA1ZMS, of Forest, Virginia, applied for an experimental license to operate a propagation beacon on 4m with the FCC in January 2010.
Because there is no amateur band on 70 MHz in the United States, the beacon runs 24 hours a day under a non-amateur experimental license.
He said, "This beacon is solely for radio scientific usage as an E-skip detecting device" On 70.005 MHz, WE9XFT is transmitting 3 kW ERP to Europe.
It is GPS locked and uses two 5-element stacked Yagis beaming at 60 degrees with a 500 W transmitter running at 7 kW ERP.
Frequencies set aside for beacons on VHF and UHF bands vary widely in different ITU regions and countries.
[11] In addition to identifying propagation, microwave beacons are also used as signal sources to test and calibrate antennas and receivers.
There are, however a few major projects coordinated by organizations like the International Amateur Radio Union (IARU).
[15] A large-scale beacon project is underway using the WSPR transmission scheme included with the WSJT software suite.
The loosely coordinated beacon transmitters and receivers, collectively known as the WSPRnet, report the real-time propagation characteristics of a number of frequency bands and geographical locations via the Internet.