Apart from that, can anyone tell me why local noise IS a
vertically-polarised E-field problem? I can intuitively (I think)
understand that it would be E-field since it is primarily a high-impedance
phenomenon; but why VERTICALLY-polarised? If it's radiated from local
house wiring etc surely it should be randomly-polarised and just as
evident on horizontally-polarised antennas? I have a 30 m vertical I
occasionally use on 80m and a horizontal dipole for 80m near it. VERY
often there is so much noise on the vertical I can't even hear my local
net; on the horizontal at the same time there is only the faintest trace
of noise and everyone is easily audible. Same on 160m. All the texbooks
agree local noise is vertically-polarised but not one of them explains why.
Hello Walter,
Maybe "local noise" is vertically polarized because it is generated
"against ground" : the wiring in the house acts as antenna, the ground as
counterweight. As far as I got it any "against ground" fed antenna is
vertically polarized, a nice example is the DDRR antenna that is a
completely horizontal construction and yet a vertical polarized antenna.
But there might be another reason for the high noise levels on your vertical :
Years ago I contructed a full-sized Marconi antenna for 7MHz. In an attempt
to be smart I connected just a few short radials and used the "house
grounding stake" as counterweight. That worked fine on TX (antenna
resistance was very close to 36 Ohm) but I had a tremendous noiselevel on
RX. Disconnecting the "house grounding stake" solved the noise problem, but
I had to add more and longer radials to get the antenna impedance back to
36 Ohm.
73, Rik ON7YD
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