On Tuesday, November 12, 2013 11:28:19 AM UTC-6, Richard Ferryman wrote:
Thanks David. The problem is susceptibility to noise from domestic

equipment including TVs (or at least their PSUs), low energy lamps.

transients from various switches such as lights or central heating and hash

from 'digital devices' such as computers and routers. Fortunately this is

only a problem on 2m but not on 23cm and above where other factors are

predominant. Two antennae of similar gain and diectivity but different

driven element types can have as much as 15 dB difference in noise floor

near the house. The same antennas on a 20' pole in the middle of the

adjacent field have near identical noise floor. It seems a folded dipole or

quad driven element is less susceptible to locally generated noise than the

simple centre fed dipole driven element. The gamma match uses capacitive

coupling to a one piece dipole so is likely to be somewhere between loop and

simple two section dipole with regards to noise floor. In all cases my

tests so far have also had VHF ferrite blocks clipped onto the feeder at the

antenna and receiver ends to help reduce noise on the sheath of some LMR200

coax..

Unfortunately I have to locate the antenna close to the houses where the

noise is worst!

Dick G4BBH

It's my opinion that as mentioned, only element static buildup
might be reduced. And in most cases, that is usually only a problem
in dry areas, sometimes in the winter during snow storms, etc..
Also at high altitudes, one example being HCJB using loop elements.
Or they used to anyway.
As far as any local noise that is received by the antenna, they should
be the same as far as s/n. No difference at all. I'd almost be willing
to bet that your case of lower received local noise is due to that
antenna having better decoupling from the feed line than the one that
seems noisier. Good decoupling is critical. If using coax, poor
decoupling will allow noise that is picked up on the outer shield
of the coax, to be piped back down to the receiver on the inside
of the shield.
I'd be willing to bet there is some problem with the decoupling
from the feed line on the noisier antenna and it's not as well
decoupled as it should be.