Re: LF: TX > RX isolation test

[DK7FC <selberdenken@posteo.de>]

Hi Paul,

Am 16.07.2018 12:17, schrieb N1BUG:
> I was planning to build a double size K9AY loop (like W1VD uses) but
> its 'gain' at 137 kHz models to -55 dBi. It seems to me this puts it
> at or below the noise output of the little vertical when moved away
> from the Tx antenna. If that is so, then I will never be able to use it!
You will need a preamp for this antenna.

The advatnage of a separate RX E field antenna is that you don't need a 
low Z ground. 200 Ohm for example is OK.
So you may use a simple ground rod far away from the house, a CLEAN earth!

On the other side, for a TX antenna, you want a ground Z as los as 
possible. It can be a noisy ground, like the mains earth ground system 
(in parallel with somethig else).
But when the TX and RX antennas are coupled together, your noise may 
rise, lowering the RX performance. Thus it is better to keep the 
antennas as decoupled as possible and use a preamp (with an internal low 
pass or even band pass filter) instead.
73, Stefan