Topband: Top Band portable operating

doktorij at doktorij at
Wed Sep 12 08:40:17 EDT 2007

"There are lots of tall trees, I would say in the neighborhood of 60'.  That 
would be plenty to string up an inverted L. The other option would  be to raise 
my aluminum tent pole mast as high as I can get it (could  go up 70-75'). As 
someone pointed out before, ground radials are going  to be the only option 
since 1/8w (to get away from ground coupling) is  60 some feet on 160 - thats as 
high as the trees. How many  radials  should I put out? I know the more the 
better, but there  has to be a point where performence vs. number of radials is 
decent  enough to not go further."

I would suggest a Tee versus an L and put up a dipole. As to radials, my experience has been that more radials are better, particularly if they are short (and mine are!) There has been reams published on the topic. Check recent back issues of NCJ for some in depth studies. In my case I have between 30 to 60 radials from 25' ranging out to about 80'. Get the vertical part into the clear (far away from trees) as possible. 
  "The next question is how many should I lay out? If the beamwidth is  10deg (I 
think thats what they are, around there) then, to get all  directions I would 
need 36. When you factor in the cost of the wire,  relays for switching, ground 
rods, and resistors.. hmm, thats a LOT of  $$. Are there any directions I should 
really concentrate on? Europe,  Africa, South America, Australia, Asia? Im sure 
I can eliminate the  majority of that 36 by focusing on a few good locations, 
rather than  trying to accomodate everything."

If you're looking at this from a contesting perspective Steve, you really only need to focus on a few directions, Europe, the Pacific, Japan and South America. You could do this with as few as two bi-directional antennas. Shorter may be better for beverages for a wider signal capture. Sure a lot easier to install, tune and keep operational fewer antennas, cheaper as well ;o) "Time is fleeting, madness takes it's toll..." Peak contest season is upon us!

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