Re: [TowerTalk] Re: One more ground radial question

[Jim Lux <jimlux@earthlink.net>]

Interesting point you raise...

In the near field, the radials are mostly there to provide a "return path" 
or image for the current in the vertical.  The question would be whether 
that "image" gets bent or warped if the radials are not evenly 
spaced.  Since they are, by geometry, very much closer than 1/4 wavelength 
apart, there's a lot of mutual interaction, and one would intuitively 
expect the current to adjust itself to be even (spread over all the 
available radials)..

Example.. if you had 20 radials over 180 deg, and 40 radials over the other 
180 deg, the current in each radial on the 20 side would be twice that on 
the 40 side, but, the virtual image formed below the radials will probably 
be exactly the same.  There's probably some limit (for instance, if the 
radials are exactly tuned, and there's not many of them, so they aren't 
strongly coupled to each other)



At 06:16 PM 12/18/2003 +0100, Jan Erik Holm wrote:
> Yes but 4 wl long you will start to "modify" the
> far field and brewster angle would get smaller.
> What you then did would not be relevant for anything
> but your QTH, i e your type of far field...conductivity
> etc etc.
> If we consentrate only on the near field I still
> wounder if you really can benefit much from haveing
> more radials in one direction (i e 5 or 10 degree sector
> forexample), I´m not convinced.
> If so you could stretch the example further. Lets say
> someone just likes to work one direction, he then
> puts lets say 90% of the radials in that direction,
> well well....no I´m not convinced.
>
> 73 Jim SM2EKM
> -------------------------
>
> Richard Karlquist wrote:
>
> > I put up a 20 meter vertical with closely
> > spaced radials 4 wavelengths long spread over about
> > 60 degrees centered on Europe.  I A/B'ed it
> > with an ordinary vertical.  The vertical with the
> > long radials had an advantage of perhaps 3 dB
> > vs the ordinary vertical toward Europe (a
> > just discernable difference).  In other directions,
> > it had no advantage.  Not what I would call
> > gangbusters.
> > Rick N6RK
> > (A report on this and other vertical experiments
> > is on my web site www.n6rk.com)

_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk