Thank you very much for this information - it is an exception to the general principal that TxGain = RxGain that I was unaware of.Do you know if it is a property only of parabolics with subreflectors? Does if matter if it is a Gregorian or Cassegrain design?
I have been unable to find a good description of this effect; if you know of one, I'm sure we would all appreciate seeing it.
To the best of my knowledge, it is primarily involved in subreflector-type antennas. I suspect that both Gregorian and Cassegrain feeds show similar properties. Again, I believe it a function of the focused beam of the transmit signal being much "tighter" than the receive, though that is a difficult piece of data to find in the theoretical extracts generally available.
And, heck, I'm just a tech!