The 'vertical' orientation may or may not match a vertical orientation on earth. It is not as flexible as the VHF mobile transceiver but it will get the job done.įor VHF voice communications, the astronauts are usually transmitting ten wattsīecause the ISS can be oriented in a number of directions at a given moment, Typically covering five, fifteen and fifty watts (as an example).Īs an in-between compromise, you may use an external power amplifier hooked up to Most modern VHF radios put out a mix of low, medium and high power One that puts out ten or more watts is ideal. Oriented more horizontal, to send out a better signal in the vertical direction.Īs the angle lowers towards the horizon, a handheld beam antenna is useful for increasing theĪntenna gain when transmitting and receiving.Ī better setup is to use a mobile or base VHF transceiver radio. When the ISS is that close, you can make contact using a rubber duck antenna.Īs the ISS moves overhead, do not forget to rotate your handheld so that the antenna is You can see it is possible to talk with the ISS using a 5 watt walkie when it is overhead,Īnd the crew is awake and at the ARISS radio station. With some noise as heard by the astronauts. Provided you're the only station operating within sight of the ISS.įive watts of radio output fed into a unity gain vertical antenna is adequate to 900 miles Ten watts of radio output fed into a unity gain vertical antenna such as a ground plane is adequate To about 1,350 miles when it approaches the horizon. You can think of it as making a long, long range two meter FM simplex contactĭistances from the ground to the ISS can vary from about 215 miles when the ISS is overhead, Over greater distances than you've experienced on earth.

Iss orbit range day