In a message dated 3/18/2001 14:51:27 Eastern Standard Time,
> If you build the proper feedlines so you have approx 50ohms of +J (3/8WL
> feedline 50 ohms) You can make the unpowered dipoles act as reflectors.
> This kind of array has its beginings with the old K8UR array which had 5
> dipoles pulled out from a single tower.
I have tried that and have one working right now. If I set the individual
radiators (3x) for 50 ohm impedance and run the array as 1 radiator with two
stub tuned reflectors, the impedance is fine, 50 ohms (F/B or pattern is less
than what I would like to have), but when I switch to other configurations
(two radiators, one reflector) impedance changes (hard to see any pattern,
any time). Behaves the same here with soaked (average) ground and by the salt
water. It seems that parasitic vertical arrays suck (for max F/B).
This is why I am trying to get 4 square going, which provides (on the
screen) much better pattern, but probable problem with my controller and lack
of explanation how them boxes work, what is exactly required, how to test it
and how to fix or tune in case of variation in antenna elements is hampering
We have situation where we can model the stuff, but are presented with
box that should work, just plug it in (trust me, it works :-). Some
explanation and specifications would go long way in helping us to use and
adapt them properly.
When I first got instructions for 80m Comtek box and we wired it up at
VE1ZZ, the numbering in the instruction book was confusing, ports, directions
and positions on the switch were numbered 1,2,3,4 each meaning different
thing (and not correlated). My new instructions have corrections by hand
after I brought it up. (After operating contest beaming wrong ways, still
good enough for world #1 :-)
I have gone through W4RNL material, it is excellent work (on paper) and
saved me some digging and fooling around, but things are not as easy with
real life wires and tubing and magic boxes.
It looks like my problem might be caused by faulty ACB-10 box and
possible problem with radiator's impedances of abt 110 ohms being out of
range for it.
I need sharp, vertical switchable array on the beach to complement the
rest of the antenna artillery, this is why I am persuing 4 sq.
I also managed to model 3 el. Quad and I was pleased to find that
computer says that (I was right) Quads are not as dumb as some say.
I think Stackmatch will be ideal for switching and phasing between
different antenna systems, but this parasitic triangular array is not what it
looks like on the computer or what what I would like. Anybody else have other
Clock is ticking and I am sitting (again) with bunch of (mismatched)
vertical dummies, but living, learnig and enjoying every (frustrated) minute
of it :-) Been there before, will do it again.
Thanks for any light sheding input!
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