In a message dated 97-10-22 20:41:34 EDT, jreid@aloha.net writes:
<< Do the legs of V-beams have to be exactly equal
in length?? I know they should, but as the
terrain beneath each leg is so unequal, and
the far ends will not be at equal elevations,
will several dozens of feet in length difference,
out of several hundred feet matter too much.
Present situation re leg length: >>
Jim,
Each leg will present a slightly different impedence, even if they are at the
same length. My recommendation would be to take impedence measurements of
each leg (independently) against the same (common) ground. I would attempt
to balance them through adding or subtracting length. In some cases, this
might mean a slight zig-zag at the end of the leg, but it will have little
effect on the overall pattern.
I may have missed it in your text whether or not you plan on using seperate
feedlines for each Vee, but you can feed all the legs with a single balanced
feedline, and a very simple switching network. I'd recommend this, and if
you have relatively good balance on each leg, you'll be able to switch
directions without having to change tuner settings.
I've done a lot of work on this concept, and designed a killer field day
switchable vee-beam antenna that really showed some excellent directionality.
Please don't hesitate to ask if you'd like more info.
73, Paul
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