Topband: electrically shortening a tall grounded tower

k3bu at k3bu at
Sat Sep 26 07:13:42 PDT 2009

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 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> > >      > _______________________________________________> Topband mailing list> Topband at>> 

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