[TowerTalk] Celwave 4bay dipole
Jim Lux
jimlux at earthlink.net
Wed Nov 9 09:50:58 PST 2011
On 11/9/11 9:41 AM, David Robbins wrote:
> no, its worse than that... he is going lower in frequency so needs an element and coax stretcher. fortunately it is only about 1% so shouldn't be too hard.
>
>
> Nov 9, 2011 12:39:12 PM, robrk at nidhog.net wrote:
>
> Nothing is easy.... You might get away with trying to shorten the dipoles, but all the phasing lines are also cut to frequency... It might match, then end up with funny lobes, pointing at the sky.
>
This might be a good application for a quick modeling in something like
NEC. The fact that the elements are slightly short isn't a big deal,
you can probably tune out the reactance with some lumped component. But
what you'd want to do is figure the feedline lengths so that the
relative phases are correct, and that's something that a modeling tool
will help with.
You *might* be able to do with 4nec2 and using its optimizer to change
the lengths of the TL or parameters on the NT card.
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