Fractenna wrote:
A radar telescope--using a dish--can be dangerous and the EIRP can be
megawatts.

More techno-folklore.

The only heating power available is the power supplied up the feedline.


Well, why don't you go on the catwalk at Arecibo and see if they'll let
you try a little experiment while the radar is on.


It doesn't matter whether it's Arecibo or just an open waveguide, you
cannot ever be heated by more energy than is being supplied by the
transmitter.

The transmitter supplies all the available energy - there is no other
energy source involved - and it all comes out of the feedhorn. If you're
on the catwalk close to the feedhorn, and if there is enough energy,
then of course you'll feel it.

But that interaction involves only the transmitter, the feedhorn and
you. The dish and its gain have absolutely nothing to do with it. If the
dish were completely removed, you would still experience exactly the
same.

I am speaking from knowledge, my friend.

I know that you possess the knowledge; but that's not where you're
speaking from.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek