Satellites

Amateur Radio Satellites

To understand and work amateur satellites, it is important to know the basics of how they operate. This page will explain what a satellite is, the different types of satellites, what satellites are used for, the different orbits and, where to find the frequency and location for each satellite. Knowing about satellites will also make it easier to know what equipment is needed and steps to prepare for operating amateur radio satellites.

Satellites: The satellite is any man-made object being placed into orbit by rocket. They have sensitive equipment and cameras to study earth and other planets, as well as instruments to monitor our planet and communicate the information back to ground stations on Earth. The purpose of the satellite determines its’ size, orbit and layout. They all adhere to the physical laws and math calculations once in space.

Most common satellites:

• Communication satellites: receive and transmit signals for radio, television, telephone and internet communications.
• Earth observation satellites: monitor the earth to report back what they observe.
• Navigation satellites: transmit signals to accurately populate data for the Global Positioning System (GPS).
• Astronomical satellites: are very large telescopes in space used for viewing the far reaches of our universe (for e.g. the James Web telescope).

Common Orbits:

After launching from earth, the satellite will be placed in its orbit. Each type of orbit has its’ designated distance from the surface of the earth.

• Low Earth Orbit Satellites (LEO) that contain amateur radio equipment are in an orbit between 160 kms and 1600 kms above the earth surface. These amateur radio satellites are the most common and are pretty quick to pass a location on earth.
• Medium Earth Orbit Satellites (MEO) that contain amateur radio equipment are in an orbit between 2000 kms and 35,786 kms above the earth’s surface. These are less common and take much longer to pass a point on earth.
• Geostationary Satellites (GEO) that contain amateur radio equipment are located 35,900 kms from the earth and are strictly above the equator. These satellites are travelling at the same speed as the earth is spinning which keeps them in the same location above the earth’s equator.

Frequencies and location:

The frequencies used by amateur radio satellites vary between High Frequency (HF) at 29 MHz through to Super High Frequency (SHF) at least 10 GHz. Each satellite has been allocated certain frequencies for the uplink (receive frequency or frequencies of the satellite) and downlink (transmit frequency or frequencies of the satellite). The mode of those frequencies could be Single Side Band, Frequency Modulation or digital in manner.

To locate satellites orbiting the earth, there are many computer software programs available and apps for the tablet, or smart phone. They use up-to-date orbit determination data to identify the location of each satellite. A few examples of programs are: “SATpc32”; “Satellite Tracking”; or, “Nova for Windows”. “ISS Detector” is an example of an app for the smart phone. These can be downloaded and installed to track many of the satellites orbiting the earth today.

Stay tuned for future articles about Antenna Polarization, a more in-depth look into an amateur satellite, components of a satellite station and communicating using those satellites.