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Radar Satellite Bounce : Link Budget assuming satellite with passive retro-reflecting antenna.

This page assumes a passive satellite with an antenna beam pointed at your earth station site. The satellite antenna is assumed to be designed to reflect some of the power received directly back into the same beam coverage.  This might happen if the satellite dish antenna feed comprises a circular ring aperture or horn.  Note no amplifier or frequency change at the satellite. Maybe some doppler frequency shift due to orbit movement.


Earth station transmit and receive efficiency = 65%.
Effective area of satellite rx dish = 50% of physical size
Satellite tx dish efficiency = 50%

If you assume a reflection based on just a 'random shape' then there will be more or less omni-directional radiation from the satellite and far worse results. I will have to look into what  'radar cross section' means? I suggest adjusting the satellite size till the satellite antenna gain is 0 dBi, if you want.

This calculator is speculative only. Probably wrong somewhere ! Tell me if you have comment to make. Thanks.

Frequency GHz
Uplink tx antenna diameter m
Uplink antenna transmit gain dBi
Uplink antenna, power at the feed W
Uplink EIRP dBW
Range (35778 - 41679) km
Uplink path loss dB
Uplink pfd at satellite dBW/m^2
Bandwidth Hz
Diameter of satellite antenna m
Effective area of sat antenna m^2
Power at satellite antenna feed dBW
Downlink satellite antenna gain dBi
Downlink satellite EIRP dBW
Downlink receive antenna diameter m
Downlink system noise temperature(antenna+LNA) K
Downlink receive antenna gain dBi
Downlink receive antenna G/T dB/K
Downlink path loss dB
Downlink C/N dB

It does not look too hopeful to me unless some high power radar is used.

For something more realistic try 0.442 GHz, 26m diameter antenna and transmit power 32000000 watts, bandwidth 100 Hz.

More about radar range calculations: http://www.waves.utoronto.ca/prof/svhum/ece422/notes/24-radar.pdf

If we can get C/N better than -27 dB C/N in 2500 Hz reference bandwidth WSPR will work.? How about dishes pointed at points in the sky where satellite regularly pass by. e.g. O3b satellites above the equator, constellations with many satellites in many orbit planes, in polar regions dishes aimed at 250km above the poles where many satellite pass frequently?

Any problems or comments please e-mail Eric Johnston

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Last Revision: 10 Apr 2020