[Elecraft] Inverted-L (was OT: Vertical antenna)

[Mel Farrer]

It is a matter of loss or lack of it.  If you look at the takeoff patterns of a 
vertical antenna on a perfect ground and then with increasing loss, the pattern 
is modified to have increasing less energy on the horizon.  However, this is the 
loss factor, not necessarily due to lack of resonance.  As one removes the 
antenna network from direct ground, and substitutes radials, several things 
happen.  IF, and that is a big IF, the amount of coupling to ground is 
maintained with non resonant radials or resonant radials are used, eff and match 
will remain .  Example, a mag mount antenna or a ground plane vertical with 
three or four resonant radials works fine and any elevation.  Just a point of 
thought.

Mel, K6KBE






________________________________
From: Steve Ellington <n4lq at carolina.rr.com>
To: Guy Olinger K2AV <olinger at bellsouth.net>; Vic K2VCO <vic at rakefet.com>
Cc: elecraft at mailman.qth.net
Sent: Mon, December 20, 2010 3:44:28 PM
Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna)

Guy:
Very interesting....

Some of your comments were verified in a recent QST article.

Mar 2010 - QST (Pg. 30)

An Experimental Look at Ground Systems for HF Verticals
The author experimented with resonant vs nonresonant radials on the ground 
and found performance improved when the radials were cut to electrical 
resonance vs just measuring them with a tape.

Given this, it stands to reason that if the same radial field is used by a 
multiband vertical on a higher frequency, the high current point would be at 
some distance from the antenna's base thus reducing efficiency.

Now here's the question....
Folks assume ground radials to be (non resonant) but that isn't the case. So 
what would be the best solution for a multiband antenna with ground radials? 
Well if we follow this idea, we would need multiple 1/4 wavelength radials 
for each HF band for best performance.

My inverted L is 50' up and 150' out. I use a separate elevated counterpoise 
for each band. I've found that a ground rod and some buried radials have 
virtually no effect. I just use them for lightning protection.

Steve
N4LQ 

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