Satellite repeaters are no different to a regular terrestrial repeater used by your ham radio group, except that they are in space! Like any other repeater, there is a pair of frequency to use: one for transmitting (TX) and one for receiving (RX). In satellite repeaters, the TX frequency is called the uplink, while the RX frequency is called the downlink. Most satellite repeaters require an inaudible access tone played at the beginning of a transmission (it acts like a pass key).
There are a number of satellites that are accessible to anyone with an amateur radio license. The easiest satellites are the following, with corresponding info on uplink and downlink frequencies, as well as the required tone for repeater access.
|Tone||Power Required (Minimum)||
License Required (Philippines)
|FOX-1B||AO-91||435.250 MHz||145.960 MHz||(none)||5 W||Class C|
|FOX-1D||AO-92||435.350 MHz||145.880 MHz||67.0 Hz||5 W||Class C|
|LAPAN A2||IO-86||145.880 MHz||435.880 MHz||88.5 Hz||5 W||Class C|
|Saudi OSCAR 50||SO-50||145.850 MHz||436.795 MHz||67.0 Hz||5 W||Class C|
|DIWATA 2||PO-101||437.500 MHz||145.900 MHz||141.3 Hz||5 W||Class C|
Any portable radio will work, especially for overhead passes, but in order to improve signal transmission and reception, external antennas must be used. You can use any antenna, but the ones that work best are the directional types (Yagi-Uda for example). To view the antenna I use to communicate via satellites, head directly to My Satellite Antenna.
Making a QSO via Satellite
Here’s a demonstration on how I used a two-way radio and a homebrewed antenna to contact local and foreign stations using the AO91 satellite. Notice how I tracked the satellite using a home-brewed antenna.
Satellite communications continue to be an exciting hobby. I hope this overview has inspired to give it a try and learn another way of enjoying amateur radio! In my future posts, I will discuss in detail how to build a simple satellite antenna to greatly increase your chances of accessing the satellites.
Night Sky in Focus
Astronomy and Amateur Radio
© Anthony Urbano (Manila, Philippines)