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Topband: Addition To SteppIR For 160, 75/80, 60, 40 and 30.

To: topband@contesting.com
Subject: Topband: Addition To SteppIR For 160, 75/80, 60, 40 and 30.
From: George Badger <gbadger@sbcglobal.net>
Reply-to: George Badger <gbadger@sbcglobal.net>
Date: Tue, 8 Jan 2008 16:05:40 -0800 (PST)
List-post: <mailto:topband@contesting.com>
Topbanders
About a year ago I put up a new 3 el SteppIR. It is a sensational antenna. I 
did not want to lose low band capability so I put a loop over the top of the 
steppIR in  the plane of the boom. All matching and connections for 30, 40, 60, 
75/80 and 160 are made at ground level so there is no tower climbing. On 160 TX 
the loop is driven on one side against a loop radial system in my basement and 
the other side is left open. The total length of the loop wire is somewhat more 
tha 1/4 wl but it is bent over in the middle so the height is only about 1/8 
wl. The pattern is omni to 0.1 dB whereas an inverted L at the same height 
loses about one dB
in the pattern and the loop has only one support.
I don't have room for a separate RX ant. so I tried the loop on EZNEC connected 
like a K9AY. It didn't work so I tried adding reactance in series with the 
loop.That worked. By adjusting resistances and reactances at the load end and 
at the source end I could get between 30 and 49 dB F/B with Minninec, high 
accuracy, perfect and freespace grounds.
The EZNEC results looked good but I still did not believe the results so I 
tried it in the real hardware wold. It works! I measured more than 30 dB F/B 
and the loop is big enough so a preamp is not needed.It's nice to have a high 
performance RX beam that rotates and is physically the same as the TX antenna.
The whole system worked so well that I wrote an article for QST. It will be in 
the Feb. issue coming out now. Take a look.

73

George    W6TC
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