"AndyS" wrote in message
...
Andy asks

When one uses the equations for a loop antenna to determine what
voltage will be developed at the antenna terminals due to a passing
signal,
is the calculated voltage with the antenna terminated in an open
circuit,
or a resistance equal to the characteristic impedance of the antenna,
or some other load ?

I haven't seen any of the texts state specifically whether the
voltage
is open circuit or otherwise....

Same question for any antenna ---- if I use Power Density times
Capture Area , it implies that the antenna is terminated in a
resistive
matched load....but I haven't seen it specifically stated. Perhaps
the
issue is too obvious to write down. But I would like to see it.

I would appreciate some small discussion on this. It is a very
simple
thing to clear up if anyone here has first hand knowledge of the
issue.

Thanks, W4OAH


The simplest case is to specify that the antenna is terminated in a
resistance equal to its own radiation resistance (e.g. 73 ohms for a
thin-wire dipole) then the sums are made straightforward and equal amounts
of power are developed in the termination and the antenna. If the antenna
is essentially lossless, the power 'dissipated' in the radiation resistance
is re-radiated.

Open-circuit voltage wouldn't be a good guide to its coupling factor for a
lot of common antennas (which are called on to produce current) but, of
course, it works fine for active monopoles.

Chris