[Lowfer] Loop antenna question

[Zack Widup]

What about using a multi-turn loop with the same diameter as the one-turn
loop? What's the difference between a one turn loop and a two turn loop of
the same diameter?

Zack W9SZ

On Sun, Mar 13, 2022 at 4:19 PM Steve Ratzlaff <ratzlaffsteve at gmail.com>
wrote:

> I too wondered about this, and did my own experiment just now. I had a
> 20' piece of 1/2" aluminum fuel line tubing already as a single-turn
> loop, and used that. It measures 6.43 uH at 100 kHz (DE-5000 LCR
> meter).  I thought I'd use my weakest daytime beacon as a check (251 SV,
> NM). I wound a 10:22 turn matching transformer to approximately match to
> 50 ohms at 251 kHz.  But even with a 11 dB Norton amp the signal was
> down at the noise floor and not usable. So I switched to 25.2 kHz which
> is a strong signal here in Southern Arizona keeping the transformer's
> turns ratio and the Norton preamp.  The 20' circumference is about a 6.4
> foot diameter loop; I pointed it toward North Dakota for peak signal. I
> used the Perseus SDR, 100 Hz CW bandwidth, Slow AGC and measured about
> -95.5 dBm.
>
> I took the loop down, measured 10 feet in and put tape there, then made
> a rough two-turn loop with rough 10 foot circumference per turn, with
> about 5-6 inch spacing between the turns and put that up. It measured
> 7.11 uH which I figured was close enough to the previous one-turn loop's
> inductance to use the same matching transformer as before. I used the
> same Norton preamp. This time the signal measured -108 dBm with the same
> Perseus CW 100 Hz bandwidth. So quite a bit lower signal compared to the
> one-turn loop, at 25.2 kHz.
>
> Take this data for what it's worth to you, perhaps at least interesting
> anecdotal results--but it does appear to go along with J.B.'s
> comments.    :)
>
> 73,
>
> Steve AA7U in AZ (south of Tucson)
>
> On 3/12/2022 7:54 PM, John Bruce McCreath wrote:
> > For a given length of wire, would a single turn loop pick up more signal
> than
> > a multiple turn loop?  The single turn loop would have a larger capture
> area,
> > so it should produce better results than if the same length of wire was
> used
> > in a multi-turn loop.  However, there may be other factors that I’m not
> aware
> > of, so I’m asking for your comments and suggestions.
> >
> > 73, J.B., VE3EAR
> >
> > LowFER Beacon "EAR"
> > 188.831 kHz. QRSS30
> > EN93dr
> >
> >
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