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From: "Ashlock,William" <William.Ashlock@edwards.boc.com>
To: rsgb_lf_group@blacksheep.org
Subject: RE: LF: RE: Re: loops
Date: Fri, 8 Mar 2002 13:15:31 -0500
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Hi Rik,

>What really looks interesting for a loop installation, according to the
>math, is the effective power gain that can be achieved by stretching the
>horizontal dimension. On my property I can make this 350ft (if it were
>legal) because of this strange narrow "L" shape out back in the woods.  The
>effective power, then, increases 50x! Tried this for an hour at very low
>power (don't tell the FCC), and it works!

>What math do you use ?

I'm using the equations out of the ARRL Antenna Book.

>I dug up a formula for small loops (I suppose any ham-sized loop is 'small'
>at 2.2km / 1.33mi wavelength) :
>R = 320*Pi^4*A^2/L^4 , where R = radiation resistance in Ohm, A = loop area
>and L = wavelength.

>So based on that a 10m high and 100m long loop should perform as well 32m
>high square loop. Doubling the length of a long&low loop should increase
>the radiation resistance by 4 and the loss resistance by 2, resulting in an
>overal gain of 2 (= 3dB). Does the above fit with your math ?

I'm with you except that a gain of 2 would translate to a 6db increase. 

>I like the idea of an L-shaped loop ( I suppose you mean lazy-L, so the
>loop is not straight in the vertical plane) as I presume that this will
>reduce the sharp nulls in the radiation pattern.

The "L" is the shape of my lot. The loop would be only across the 370ft
(stright-line) portion. I  don't think you can reduce the null in any way. A
loop is a loop; can't modify the shape without reducing the field. 

>>My first TX loop article just appeared in the US Longwave Club's 'Lowdown'
>>publication. The second is to follow next month.

>Sounds interesting, is it available on the web?

Not sure. Try the Crawley Club sight. If not there, I'll send you a copy.

Bill A


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