How tall is the tower?
There are actually benefits of having taller than 1/4 wave, up to about 1/2
wave.
One way to "insulate" the tower portion is to use the "trombones" - hairpin
stub with capacitor to tune it.
Yuri, K3BU
www.MVmanor.com home of Oktoberfest ----- Original Message -----From: Bob Kupps
Date: Saturday, September 26, 2009 12:52 amSubject: Topband: electrically
shortening a tall grounded towerTo: topband > Hi> Is there any effective way to
electrically shorten a tall > grounded tower to 1/4 wave? I tried modeling a
1/4 wave cage > surrounding the tower but it still shows a lot of current in
the > protruding section with resulting high angle radiation. Then I > tried
modeling a 1/4 wave stub above the cage grounded at the > top to the central
tower which appeared to turn it into a dipole > and still significant current
above the stub. I was also > thinking of using an external parallel resonant
trap/choke but > would this actually work when situated at a zero current point
> at the far end of a 1/4 wave monopole?> Thanks and 73 Bob N6BK/HS0ZIA> > >
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