"Reg Edwards" wrote in message
...

Wouldn't it be better to use a pre-amp at the loop feed? The gain of
the
pre-amp could make line pickup a negligible effect, and the pre-amp
would
match the coax very well.

--
Ed
WB6WSN
El Cajon, CA USA

It might be. But the extra complication of powering an amplifier would
bring another load of things to worry about. Simplicity is a
wonderful thing.

By far the best way of improving performanc and reducing possible
measuring errors, is to increase size of loop relative to length of
feedline. Doubling dimensions would make a world of difference.

I suppose he had a good reason for choosing a 1/2-metre square loop.
----
Reg, G4FGQ

I have done some more calculations on a square loop fed at the corner. I
agree with your results of input impedance. NEC 2 shows Zin at 0.388 +
j109. The radiation efficiency of such a loop is 2.88%. I have made a very
careful analysis of the currents in the loop when in the presence of a know
E field. The current appears to vary in a sinusoidal manner around the
loop, with very slight discontinuities at the corners. I assume the
variation in current is due to the fact that the induced current is
different on those conductors normal to the dipole axis.

Using the RMS current through the 50 ohm load resistor at the corner, and
more careful calculations, I obtain an antenna factor of 60 dB, or 24 dB
more than your findings. It will be interesting to find why we have such a
large difference.

Regards,

Frank