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Re: [TowerTalk] Yagi gain vs rotary dipole.

To: Jim Thomson <jim.thom@telus.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] Yagi gain vs rotary dipole.
From: Steve Hunt <steve@karinya.net>
Date: Mon, 24 Nov 2014 23:14:08 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Jim,

I did exactly that when I was developing the hexbeam. I had a reference dipole at the same height on a different mast, "pointing" in the same direction. I A/B switched at 1 sec intervals while listening to a CW signal. The receiver AGC was off and the gains were adjusted to put the signal in the linear part of the receiver characteristic. I fed the audio into a PC sound card and measured the step changes with some audio analysis software.

Mostly the hexbeam was stronger, sometimes there was no difference, and just once or twice the dipole was stronger. This is the sort of distribution I got:
http://www.karinya.net/g3txq/temp/hex_gain.png

Modelling had predicted the hexbeam would be +3.5dBd.

I would never normally have attempted to measure the gain on sky-wave signals, but someone on one of the discussion groups was adamant that the hexbeam's gain is significantly higher on sky-wave signals, and I wanted to prove them wrong!

Steve G3TXQ



On 24/11/2014 16:37, Jim Thomson wrote:
Has anybody actually measured the gain of a yagi vs something like a rotary 
dipole.... at the same height ?


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