Topband: top guy cancellation

[W7lr@aol.com]

Is this real or a myth?  I wondered and so asked Al K3LC.  He  studied the 
question and had a good article about the topic.  For 160m I  use a 90 foot 
irrigiation pipe vertical with four
wires in part of the top guys, each 42 feet long.  The antenna looks  
electrically like a quarter wave.  So there is some improvement in the base  
impedance, which helps make a matching network and antenna more  efficient.  The main 
question however was about the shielding or signal  cancellation effect of 
using such top loading.  If I interpret his article  correctly, the antenna 
radiates equally well with or without such top  loading.  There is however a big 
benefit of using such top loading - much  better bandwidth when that is used.  
My results compare well on bandwidth  with this data in his article.  With two 
matching L networks, each with two  ceramic doorknob capacitors, I can 
transmit anywhere in the 160m band with low  swr. And it has helped me work 209 
countries on 160m, which isn't too bad from  Montana.  
73 Bob W7LR   _w7lr at aol.com_ (mailto:w7lr at aol.com)