|Subject:||[TowerTalk] Rectangular loops|
|Date:||Thu, 14 Oct 2004 23:59:07 +0000|
Is the silly season on TT over yet? Here's one that I'd appreciate some help on.
Due to termination of employment, I had to move into cheaper accommodation, swapping a good horizon & nearby salt water in strategic directions for something on a piece of farmland in a valley with a lousy horizon & no salt water to be seen, but quite a bit more space.
On the farm there are two three floor concrete houses, roughly 8m square &
10m apart, not in line but offset. A 5m roof tower supports antennas for the
higher bands on one & is shunt fed against elevated radials for the low bands,
but with the top about only 13m above the ground, there is no way to put
horizontal LF antennas up high enough to work well for DX. About the only
thing I could do is try some end loading on the SteppIR dipole at the top of the
mast, but that idea went nowhere on TT when raised the other day.
A tribander will soon go on the tower, so it will become far longer electrically &
I am finding it already works better on 80 than 40, so the days of shunt feeding
the tower on anything other than 80 are about to end.
So instead I have considering things like half-squares, or phased verticals. The phased verticals could mount to a 2m tall wall that surrounds the property & in places is conveniently aligned for the shot to EU & NA. The phased verticals could do double duty on 30 & 40 & a pair could switch between those two directions & be less of a clutter than a pair of half-squares, which would not do well on 30 when cut for 40.
I was playing with EZNEC yesterday & modelled some rectangular loops. There is enough space to hang one that is reasonant at about 8 Mc between the two houses (about 17m, which keeps the vertical portions away from the walls). Such a loop still shows good pattern, take off angle & a little gain on both 40 & 30m, but doesn't present a good match on those bands.
With the vertical portions of the loop about 8m long & the bottom of the loop about 4m above the ground, fed at the side is something like 40-j160 (with j going down a bit towards 0 across the band, towards where the loop is reasonant) on 40 & varying from 1000+j5000 to 4000+j9000 across 30.
Is that something that a typical tuner can handle? I think I can put two of these up at close to right angles & route the feeders to my balcony on the third floor.
Anybody anything like this for an antenna & can comment how it compared to others at the time?
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
_______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk
|<Prev in Thread]||Current Thread||[Next in Thread>|