On 6/20/2012 7:24 AM, W5DXP wrote:
On Wednesday, June 20, 2012 2:12:09 AM UTC-5, NM5K wrote:
If an antenna were immune to noise, it would be immune to all
signals.

Don't forget the effects of polarization. At my previous QTH, my horizontal dipole was about 2 S-units less noisy than my vertical even when communicating with remote vertical antennas.
--
73, Cecil, w5dxp.com


I'm not. I'm just trying to show that an antenna can't tell what
is noise, and what is an actual desired signal. To the antenna,
they are both the same. RF.. One can not magically filter noise,
without filtering the actual signals along with it.
This applies more to the small receiving loop, comparing shielded
to non shielded, but also would apply in most any other case.
I'm fairly comfortable saying the claims of reduced noise pickup
with shielded loops is a myth. I've compared them, and I saw no
difference here. And that includes the usual far field signals,
but also closer local noise, such as monitor noise from the shack,
etc..
I never saw any difference with that type of local noise either.
Both types picked it up equally well if it was there.
And both types could null it out equally well, if from a single
source.