Topband: Adding a parasitic reflector to a vertical

W7RH midnight18 at
Tue Jan 30 23:38:33 EST 2018

I've played with parasitic elements in antenna arrays for almost three 
decades and the current antenna system I have used parasitic elements 
both director and reflectors.

With very careful tuning performance that of a all driven array can be 
achieved. Tree is correct they due tend to be somewhat limited in in 
bandwidth with relation to F/B ratio. Gain remains fairly constant.

The tuning procedure that Tree suggested is absolutely correct. You 
detune all unused elements and adjust the center frequency of the 
parasitic for best F/B one element at a time. Parasitic elements I might 
add are no different than driven and must have extensive ground system 
to be effective. No exceptions. You know you have right by F/B ratio. 
You can go one step further and measure the actual antenna currents 
which I have done. In my system the parasitic elements achieve 80-85% of 
the theoretical current at the base.

de Bob W7RH


It has become appallingly obvious that our technology has exceeded our humanity.

Albert Einstein

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