Topband: Non-optimum antennas

[Pete Smith <n4zr@contesting.com>]

At 05:53 AM 12/6/2004, Tom Rauch wrote:
> Frankly Greg there is no iron-clad rule about how these
> systems work and what they do. Results depend heavily on the
> tower and what is on it and a half-dozen other things.


Tom makes a point I've been wondering about, based on my experience.

Since about 1958, I have been off 160.  Last fall, I decided to try to 
shunt feed my 97-foot tower with three yagis on it, one side-mounted at 69 
feet and the other two on top, with mast extending to 104 feet.  This 
figured, by rule of thumb, to be well over 1/4 wavelength 
electrically.  Further complicating matters, the tower supports a 4-element 
80-meter lazy vee dipole array.  In order for the array to work properly, 
the dipole feedlines must be brought in to the tower somewhere 25-30 feet 
above ground, and thence down to the switchbox.

Amid warnings that it couldn't work, I tried a shunt feed at 40 and 50 
feet.  A straight gamma produced no match, so I hooked up an omega match, 
which readily brought the SWR in to 1:1 at 1830.  Laid out a few 120-foot 
radials.

To my surprise, the antenna seems to work quite well.  Even with only 200 
watts, I seem to be louder at the other end than other stations are 
here.  I broke a number of pileups last weekend, and worked RO4M/6 first 
call, when he was barely audible here.  Question is, why?  I would welcome 
any speculations about why this crazy arrangement works at all, much less 
why it seems to work fairly well, as well as any thoughts for 
improvement.  Or should I just put out more radials, and then relax and 
enjoy it?

73, Pete N4ZR




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