In article ,
"Arthur Harris" wrote:

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The "free space path loss" between Earth and Mars at 15 MHz would be 211 dB.
That's a HUGE loss. At UHF and microwave frequencies the path loss is even
greater, BUT the use of very high gain dish antennas both on Earth and Mars,
as well a low noise figure receivers, makes communication possible. At HF,
antenna gain of more than about 10 dB is hard to obtain. And the
atmosphereic noise at HF is a killer for weak signal reception.

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How did you calculate this loss? I'm assuming you mean the 211 dB to be
an absorptive loss? Maybe you are considering the antenna on Mars to be
a point source off a 180 degree ground plane so the loss figure is power
distributed over a half sphere with the Earth - Mars distance?

--
Telamon
Ventura, California