Topband: shunt fed tower - question?

[Dennis OConnor]

 >I wonder if two conductors will obtain the "shielded from the outside world" effect >refered to above? Does it make any difference?

Herb, my suspicion is that two drop wires will act more like a folded dipole than acting like a full skirt... 
I expect it will take a minimum of three wires at 120 degree spacing to begin to act like a coaxial skirt - and it will be leaky...  
If you want a true skirt you will need a number of drop wires, 4+, with cross ties around the skirt at least every 1/16 wave...  Certainly, you can get some benefits as a fatter conductor from fewer wires and no cross ties so the effort is not wasted, but I doubt you are getting the full skirt effect...

A few years back I spent considerable time and effort fooling with drop wires, folded uni-poles, varying spacing and diameter of wires, etc. using my quarter wave stick as the support.. They all worked but none of them are still up - which speaks for itself...  W8JI and I had some repartee over these issues on this reflector, as I remember...  I was at one point using the folded dipole at varying spacings from the tower to act as an open sleeve element for driving the tower...

Doing a full skirt around the quarter wave, 160 tower is still on the to-do list, just waiting for it's turn... But, it will be done a bit differently (like every thing I do)... It's purpose will be so that I can remotely tune the electrical length of this vertical element... There's more to the story, but I tend to rattle on too much anyway...



cheers  ...  denny - k8do



			
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