[Amps] new amp race

[Victor Rosenthal 4X6GP]

I think that on the lower bands, much local manmade noise is propagated 
by the "ground wave" mode.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/

On 22 May 2017 05:02, Manfred Mornhinweg wrote:
> Ron, and all,
>
>> I learned:  Natural noise (lightning) is vertically polarized because
>>  lightning is a vertical event.
>
> I have seen lots of horizontal lightning, from cloud to cloud, or inside
> the same cloud.
>
> Even when I have seen vertical lightning to ground, it has usually
> happened simultaneously with horizontal lightning, that brings the
> charges to the spot in the cloud where the vertical part starts.
>
> Of course even horizontal lightning noise will arrive at one's place 
> polarized horizontally, vertically, or anything in between, depending 
> on the direction of the lightning relative to the direction between 
> one's place and the lightning. Horizontal lightning aligned with your 
> path to the lightning generates vertical polarization at your place. 
> Just like a horizontal dipole antenna operates with vertical 
> polarization at the directions the wires point.
>
> And then again, any far-away lightning that you hear through 
> ionospheric propagation will anyway have its polarization thoroughly 
> mixed up.
>
>> Man made noise, like noise motor is generally polarized with it's
> > feed wiring.
>
> Yes. And that's typically more horizontal than vertical, because power 
> lines strung horizontally from pole to pole and pole to houses do much 
> of the radiating. But some vertical power wires exist - just think 
> about tall buildings - and of course the noise radiated by a 
> horizontal power line running straight away from your place appears 
> vertically polarized.
>
> In short, I don't think there is much merit to the idea that noise is 
> most commonly vertically polarized. Neither manmade nor natural noise.
>
> The real reason why vertically polarized antennas acquired a 
> reputation for being noisy is that many such vertically polarized 
> antennas are simple monopoles fed against ground. This places them at 
> ground level, where there is most manmade noise. Also most hams run 
> such antennas without a common mode choke, thinking that the 
> unbalanced antenna nicely matches the unbalanced coax cable. So if the 
> grounding is anything but perfect, the feedline becomes part of the 
> antenna system, and that feedline runs into the house and right past 
> switching power supplies, CFLs, power wiring, etc. Put the same 
> vertical antenna high up on a tower, using an artificial groundplane 
> up there, with a proper common-mode choke on the feedline, and it will 
> be as quiet as a horizontal antenna installed at the same place.
>
> Most people can easily do this test using a VHF antenna: Place it 
> vertically or horizontally, at the same height, and compare. Noise 
> stays the same. I used switchable polarity Yagis on VHF and UHF for 
> many years, operating on satellites. I could switch to vertical, 
> horizontal, left hand circular and right hand circular polarizations. 
> There was no general noise advantage in either of them. Just the 
> signals, and specific individual noise sources, got stronger or 
> weaker, depending on the polarization they had.
>
> On UHF I didn't have much manmade noise, but on VHF I did.
>
> Manfred
>