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Re: [TowerTalk] Method of calculating phase delay variation when stackin

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Method of calculating phase delay variation when stacking two dissimilar yagi antennas?
From: "Mark Beckwith" <r-emails@n5ot.com>
Date: Sun, 1 Sep 2013 12:06:07 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
So my question at this moment is - which is the
proper method for me to calculate the proper
delay line length to properly phase the two
dissimilar SteppIR yagis?


This is not meant to be a snarky or otherwise "cute" response. Just more like a reality check. The answer is:

Feed them with equal length feedlines and see how they play. If you like the way they work, then you're done. I suspect you will like the way that they work and I also suspect changing one feedline length by as much as 8 feet would not affect your overall conclusion.

Neither the WX0B formula or the WN9O formula accounts for imbalance caused by the dissimilar feedpoints (even if the feedpoints were identical in every other respect, one is still closer to the ground than the other) - meaning there are undoubtedly unknowns in the mix which from the seat-of-my-pants means it may largely be an academic question, likely trumped by actual implementation.

Get on the air and work guys. I bet you work more guys with two antennas at you disposal than just one antenna, and I bet when you do top-bottom-bip-bop* tests you will find some times when some stations are lounder under some of those four conditions. I suspect this would be the same conclusion whether your coaxes are the same length or different lengths by 4 feet or 8 feet.

This is what I would do anyway, and what I have found to be true in the past when stacking dissimilar tribanders in real life™.

73 - Mark, N5OT

* Top antenna alone, bottom antenna alone, both antennas in phase, both antennas out of phase
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