Nothing the sun does matters much up here. 144 MHz goes in a straight line and stops at the horizon — normally 30 to 60 miles through a repeater.
Nothing the sun does matters much up here. 144 MHz goes in a straight line and stops at the horizon — normally 30 to 60 miles through a repeater.
But when a high-pressure system parks overhead, warm air settles on top of cool air and forms a temperature inversion. That boundary acts like a pipe: signals get trapped between it and the ground and travel far past the horizon. This is tropospheric ducting, and it can turn 40 miles into 800.
It happens most on still autumn mornings, over water, and under stagnant highs. On an ordinary day there is no inversion, and you get normal range.
| FREQUENCY (MHz) | MODE | LICENSE CLASS |
|---|---|---|
| 144.000–144.100 | CW | Technician and above, General, Advanced, Extra |
| 144.100–144.300 | SSB & weak signal | Technician and above, General, Advanced, Extra |
| 144.300–144.500 | Digital | Technician and above, General, Advanced, Extra |
| 144.500–145.800 | FM simplex | Technician and above, General, Advanced, Extra |
| 145.800–146.000 | Satellite | Technician and above, General, Advanced, Extra |
| 146.000–148.000 | FM repeaters & simplex | Technician and above, General, Advanced, Extra |