[Lf] 47A of loop current: No sweat!

[Andre Kesteloot]

> -----Original Message-----
> From: majordom at post.thorcom.com [mailto:majordom at post.thorcom.com]On Behalf
> Of Ashlock,William
> Sent: Friday, June 28, 2002 5:06 PM
> To: 'rsgb_lf_group at blacksheep.org'
> Subject: LF: 47A of loop current: No sweat!
>
> Mal and group,
>
> I was just pricing out various sizes of copper pipe at the local builders
> department store for the next "dream" (or is that "pie in the sky"?) loop
> antenna. Turns out 2" ID pipe is $18 per 10 ft section which would yeild a
> 0.04ohm Rac on a 50'x50' loop, neglecting soil loss. Was actually
> contemplating reducing the size to about 1/4th the area to allow raising and
> lowering the loop to  measure various losses without a reduction in the
> basic radiated power @ an input of 1w.
>
> Then I did a little 'wild math' (or call it 'wildfire' math) to determine
> the dimensions of a 47A loop (still at 1w to keep it legal) that would have
> the same radiation as my 50'x50' 1/2" pipe loop. Considering my present
> 1.8A, going to 47A would allow a 47/1.8 = ~25x reduction in loop area. The
> new area would be 2500/25 = 100sq ft or 10ft per side. So far, so good. But
> in order to achieve 47A @ 1w the Rac of the new loop would have to be
> 1/(47^2)= .00045 ohms. I did a bit of manipulation of the formula for Rac Vs
> conductor diameter for a 40ft long copper conductor and came up with:
> Diameter (in inches) = .016/Rac. Using an Rac of .00045 the diameter comes
> to 35 inches. Well.... not impossible! And could be fashioned from .01"
> thick copper foil - maybe $200 worth!
>
> Just thought you might want to know......
>
> TGIF!
>
> Bill A