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Rotatable Dipole

Nov 3rd 2015, 17:23

WB0FTY

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I am planning on building or I should say would like to build a couple of rotatable dipoles. One for 17 m and one for 15 m. I have a small lot so would like to put these on the same push up pole. I would turn them 90 deg to each other which they each should be in each others null which shouldn't cause any problems. The problem is I can't find any info on how far to separate them. I would think you would want to stay away from multiples of the freq's.

The other thing I thought about was getting a 20, 15 and 10 rotatable and putting a 17 m below it but there again how far to separate them. Again I would put them 90 deg from each other. Looking for some thoughts and idea's. I know I could build fanned dipoles, use GR5V's, etc but would like to be able to rotate them. Thanks.

Bernie
WB0FTY
Nov 7th 2015, 01:03

WA0CBW

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Not many takers on this question but I will give it a try. At the higher frequencies the separation is usually 1/4 wavelength starting at the lowest frequency. This might be difficult to accomplish on a push up pole. Because they are in close proximity to each other tuning one band usually affects the others (have you ever tuned a "fan" dipole?). Putting them at 90 degrees to each other will help. How far apart you put them will be dictated more by how stable the push up pole is and the ease of raising and lowering it several times while you tune each band. Let us know how it turns out.
BB
Nov 7th 2015, 05:58

WB0FTY

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Thanks. That is what I was wondering about. Yes that would be a tough one on a push up pole. So may be back to the drawing board. I just got my antenna handbook so will be doing some reading and studying.

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