[TowerTalk] Inverted Vee vs. Dipole QRN

[Jim Lux]

At 08:05 AM 11/4/2006, Bill Turner wrote:


>1. An inverted vee has a vertical component of radiation, and man-made
>noise is predominantly vertically polarized, so an inverted vee will
>pick up more man-made noise than a dipole.

Just curious.. I've heard and read the assertion of "man-made noise 
being predominantly vertically polarized", but after some casual 
research, I can't find an original source of the data.  Does anyone 
know the basis of the assertion?  Actual measurements? Where? What 
frequencies? When?

There's a fair amount of noise data out there over the years, forming 
the basis of CCITT and ITU documents, but nothing that talks about 
polarization.   There IS some old (>50 years) data showing that a 
vertical antenna showed a higher background noise level than a 
horizontal dipole, but that was more of a study on "what kinds of 
antennas should shortwave broadcast receivers use"

The RF environment has changed a lot in the last 30 or so years. 30 
years ago, there were no switching power supplies to speak of, to 
take a notorious class of RFI sources as an example. Also no PCs, no 
microprocessor controlled widgets, etc.



The other thing, of course, is that a dipole is H pol only in one 
direction, broadside to the antenna.  In other directions (and 
elevation angles) it has the other polarizations. Off the ends of the 
dipole, it's actually vertically polarized and down about 5-10 dB