[TowerTalk] Yagi gain vs rotary dipole.

[Peter Voelpel]

Hi Steve,

You probably measured arriving signals with qsb so you just proved your
method being wrong, otherwise the result would be always the same.
You need to measure and compare the major lobes just outside the near field
to compare antennas.

73
Peter 


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Steve
Hunt
Sent: Dienstag, 25. November 2014 00:14
To: Jim Thomson; towertalk at contesting.com
Subject: Re: [TowerTalk] Yagi gain vs rotary dipole.

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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