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	id xma022189; Mon, 25 Aug 97 20:56:36 -0600
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To: Jim Henderson <jhenders@tdrss.wsc.nasa.gov>, topband@contesting.com
From: John Brosnahan <broz@csn.net>
Subject: Re: TopBand: Re: the Mag-U and The New Mexico Topband
  Conspiracy
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>        John, what impedances do you see for a squashed, single-turn loop
>of what H/V side ratios? W6SAI's old radio handbook shows a loop with a 2:1
>side ratio has approx 40 Ohms Zo. Starting from there, the more you squash
>it, the more it looks like a folded dipole with Zo nearing 280 Ohms.I
>always preferred higher radiation-resistance antennas over our ground, and
>K5RP's 115+j0 for a 2-turn, 30-degree vertical loop is nearly right on the
>money. Besides, I HAVE to use low profile antennas here.

Jim, I don't have all of the modeling here and what Steve had done
was on a hard disk that died after his computer received a spike
from a lightning strike (needed new motherboard and new drives to 
repair).

I'll go back and look to see what I had gotten for results when I have a
chance, but, as you know, the 2-turn loop does a 4-1 step up in
impedance.  Steve mentions that his 1-turn loop version was right at 
50 ohms on 40 meters with 16 ft sides and with the bottom wire 
about 10 ft above the ground.

Good place to start when scaling or modeling.

73  John  W0UN




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