[TowerTalk] 80 M 4 SQUARE MODELING
Bob Shohet, KQ2M
kq2m at kq2m.com
Fri Jul 21 20:32:13 EDT 2017
In 1995 I built an 80 meter 4-square with KQ2M design 3/16 wavelength spacing with 4 elevated Inv L elements about 50’ vertical and the remainder mostly horizontal. I used the Comtek phasing box and the antenna absolutely kicked butt! In the 1995 ARRLDX CW Contest, at the low point in the sunspot cycle, if I remember correctly, I had more qso’s on 80 than any other US single op.
In 1999 I put up my 130’ Rohn 45 tower in the center of the 80 meter 4-square and populated it with 3 4 L 20 meter yagis. The 4-square still worked well but not as well as before the tower erection. Yes, that is anecdotal – but the effects were clear – the antenna was impacted by the tower and the yagis on it. I was not as loud as before and the F/B and F/S were not quite as good. It was noticeable to me on the air in the contest – I don’t know if anyone else would have noticed the difference.
I didn’t bother to model it – there was no other place to put the 4-square or the tower – you do what you have to do and put the antennas where they have to go.
Yes, the performance of your 4-square will be affected by the presence of the tower – but if that is the only place that your 4-square can go then don’t worry about it. If you build it properly it will work fine and you will enjoy using it. :-)
73 and gl!
From: Bill via TowerTalk
Sent: Wednesday, July 19, 2017 5:00 PM
To: TOWERTALK at contesting.com
Subject: [TowerTalk] 80 M 4 SQUARE MODELING
Now that I have finished my tower for 40-10 meters I need to start my next project. I'm limited to the one 90 foot tower I have by county code. I am planning on running 4 ropes from the last guy point (84ft) to install a wire 4 square for 80 meters. Wires would be suspended vertically from the ropes in a typical 4 square pattern using Comtek switching.
Before I go through all the work installing the antennas and the radials (yuch) I want to be sure the tower and all the antennas on the tower will have minimal effect on the 4 square. I'm using Philly for the guy wires so that is not an issue. I can mess with the HFTA program all day long and feel comfortable working with it. However, this is not a project for HFTA and my computer antenna modeling skills are sorely lacking.
Is there anyone out there who could model this setup to determine if the tower and antennas will negatively affect the 4 square system. I would be glad to share the exact details of the antennas, their heights, length of boom etc. off reflector to facilitate the analysis.
The 4 square is the only high performance system I can use out here due to the restrictions set by the county so any help on this would be appreciated.
73 Bill K4XS/KH7XS
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