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re phased delta loops

Subject: re phased delta loops
From: burns (burns)
Date: Mon Jun 21 11:58:40 1993
From:   NAME: Andy Burns                    
        FUNC: Research and Development        
        TEL: 0324 493981                      <BURNS,AL@A1@GRRD04>
To:     "cq-contest@tgv.com"@rcwi01@mrgate@grrd04

Steve, N2IC/0 asked about phased delta loops for 80M. 

My primary 40M antenna is a 2 el Quad array, vertically polarized with 
1/4 wave spacing using the Collins hybrid coupler system as described in 
ON4UN's bible. Switchable to East or West. When I put it together I 
measured mutual impedance by opening the loop and shorting one end to the 
ground system of my inverted L for 160M. Follow the procedure in the book 
to check out each loop.

My advice however if you've got the room is to widen your spacing to 1/4 
wave which is a lot less sensitive to inbalance in the resonance of the 
loops. The collins method (90 degree phase lag) is very easy to implement 
and gives very good performance. In practice, I ended up putting a 
phasing stub on the west loop and by changing the shorting bar (hence 
changing the loop length) I was able to tune for either maximum gain or 
maximum front to back. With the Collins system this seems to work well as 
inbalance between the loops doesn't seem to mess the phasing system 
up....I think!!

Performance wise, it works great. Came 8th World in 92 ARRL DX 40M single 
band behind ON4UN, CT1BOP and the late G3FXB (what a line up.....great 
choice of operating strategy....went back to all band for this year!). It 
seems to have a good beamwidth (60 degrees) without noticable degradation 
of received signal (in comparison with a dipole at 50 ft). 6 S units of 
rejection of close in signals from the side. Usually 1-2 S units better 
in the forward direction to East Coast or Mid West than the dipole. For a 
few bits a wire its not a bad way to get 100+ per hour to the US on 40M 
split. I'm sure 80M would be no different. I just wish I had the trees to 
hang one in.


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