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Re: LF: Noise

To: [email protected]
Subject: Re: LF: Noise
From: "Rik Strobbe" <[email protected]>
Date: Thu, 09 Jan 2003 11:22:17 +0100
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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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