Topband: RX 4 Square and Surrounding Verticals

[Dennis W0JX]

In January, I completed installation of a HiZ 4 square system which is located about 150 feet northwest of my 160 meter shunt fed tower.
Initially, there was a wire dual flag RX antenna quite close to the array as well as a 28 foot flag pole which was 42 feet behind the back vertical (looking NW). I was not very impressed with the receive performance of the array as it did not seem to have much from to back ratio, averaging about 12-15 db. The first step was to take down the dual flag - a variant of a DHDL. This seemed to improve the situation slightly but with no formal way to measure results, it was hard ti confirm improvement.

I operated the array for about five months this way and decided to take a big step and remove the 28 foot aluminum flag pole. The resulting improvement was dramatic and I am seeing over 20+ db front to back on a regular basis. Also, the antenna seems to perform better on 40 and 30 after taking down the flag pole.

I have tried shorting out the shunt feed on the tower but do not observe any change in the 4 SQ performance. Perhaps I need to detune the tower in a different way. My conclusion is that the RX 4 square is affected by any vertical conductors in the nearby vicinity of the array and that other conductors such as power lines also can affect it. Gary, KD9SV, has two such systems, one in his backyard with a 65 foot side spacing, and one out in a farm field 400 feet way with an 80 foot spacing. Gary states that he can hear signals on his open field 4 square that are not audible on his backyard array.

73, Dennis W0JX/8
Milan, OH



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Sent: Thursday, August 9, 2012 3:00 PM
Subject: Topband Digest, Vol 116, Issue 21
 
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Today's Topics:

   1. RX 4 squares (Bob Kupps)
   2. Re: RX 4 squares (Larry Molitor)


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Message: 1
Date: Thu, 9 Aug 2012 04:41:36 -0700 (PDT)
From: Bob Kupps <n6bk at yahoo.com>
Subject: Topband: RX 4 squares
To: topband <topband at contesting.com>
Message-ID:
    <1344512496.93880.YahooMailNeo at web130205.mail.mud.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Hi I would like to put up a RX 4 square array for 80/160 but the only place (just) over a half wave away from resonant verticals on those bands would be surrounding (15m out from) a 70' tower with 2 large yagis on top. Does anyone have any experience with RX 4 squares near or surrounding non-resonant towers?

Thanks Bob

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Message: 2
Date: Thu, 9 Aug 2012 05:54:59 -0700 (PDT)
From: Larry Molitor <w7iuv at yahoo.com>
Subject: Re: Topband: RX 4 squares
To: Bob Kupps <n6bk at yahoo.com>, topband <topband at contesting.com>
Message-ID:
    <1344516899.67346.YahooMailNeo at web126206.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Bob,

My Hi-Z 4-square was only 80 feet from my 160 TX vertical (which is disconnected with relays during RX periods and non-resonant). The other towers, also non-resonant, were about a half wave away. Although there was noticeable pattern distortion, the array was still very effective.?

In my experience, you would probably have more trouble with the resonant antennas a half wave away then the nearby non-resonant antennas/towers. I suggest that you use relays to make the resonant structures become non-resonant during RX periods.

Of course, ALL RX antennas will have greatly diminished performance in the presence of resonant structures including elevated radials.

73, Larry - W7IUV





>________________________________
> From: Bob Kupps <n6bk at yahoo.com>
>To: topband <topband at contesting.com> 
>Sent: Thursday, August 9, 2012 4:41 AM
>Subject: Topband: RX 4 squares
> 
>Hi I would like to put up a RX 4 square array for 80/160 but the only place (just) over a half wave away from resonant verticals on those bands would be surrounding (15m out from) a 70' tower with 2 large yagis on top. Does anyone have any experience with RX 4 squares near or surrounding non-resonant towers?
>
>Thanks Bob
>_______________________________________________
>UR RST IS ... ... ..9 QSB QSB - hw? BK
>
>
>

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End of Topband Digest, Vol 116, Issue 21
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