I keep seeing talk of 4 squares and how to move to that next step on 160 and
80 from guys like W0UN. I put out something on the antenna newsgroup last
winter and did not even raise one eyebrow.
In the new Oct 1997 QST there is a picture of DJ4ZB/ZL7ZB (page 77) and his
G4ZU birdcages. Dick Bird G4ZU (now living in F5) described this antenna in
CQ May 1960. A local (at that time) bought the commercial job sold in the
USA and EU which I got and used very sucessfully on field day in the 60's
in 3A at W5KHB. The birdcage is a quad folded back on itself with a
reflector and driven element. There is an X at the top and bottom and the
vertical wires make up the rest of the loop. Each leg of the X is 1/8 wave
and the vertical leg is 1/4 wave. The X-Beam (W9PNE et al) is just the top
section modified to be two yagi elements.
Imagine an 80 meter beam mounted on a rotating tower with 33' 1/8 elements
(66' for each leg of the X). The top at 120' and the bottom at 54'. This
is about .6Dbi down from a full size quad....and blows away our loaded 2el
beams (and even full size 2 el beams at times). Now imagine a 160 Birdcage
on a 180' tower with 64' segments and the bottom at 50 something feet. 3DBd
better (or more) than the 4 square, but if you got a tall tower....only rub
is it must be unguyed or you have limited rotation.
There is no boom so you could mount an 80 on a tree fixed on JA or EU or SA.
BTW: The G4ZU is a single band quad altho G4ZU and the people who sold it
commercially talked about a ReinHartz loop (a 1/2 wave loop is very
inefficient unless 360 ohm Rc circuits are put in the sides to force the
radiation in the plane of the antenna (see the ARRL handbook). Not knowing
any better I tried the antenna on 40 (the one I have is a 20M) and found it
worked about as good as a Hustler mobile antenna. The one in the QST
article is for 20 (top of the mast and just above DJ4ZB). The 15 is in the
middle. His scheme works (I think it was W6PQW now SK) as one ham made a
tribander by placing antennas inside each other. Maybe someone could use
the K6STI program for interaction to check this out. The W6PQW version
worked very well as he did quite well in the old ARRL SS!
Alright..who will be the first???
73, Dave K4JRB
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