[Lowfer] Loop antenna question

Sun Mar 13 16:14:02 EDT 2022

Mike, J.B., John & All:   Mike's comparison of the LNV to the single turn and multi-turn loops are interesting and for me at least somewhat expected.  But the LNV is not 100ft wire, so there is some "Apples to Oranges" comparison in this example.
I found SM5BSZ's "sensors videos" to be interesting, as in Part 4 of his sensors videos, he compares e-probe and active single turn loop antennas of similar physical size.
In this Part 4 Sensors video at 9:34 minutes in, he combines the e-probe and loop signals orthogonally, and their is a noticeable (6db-ish) improvement in signal to noise ratio using the e-probe output to cancel some of the E-field noise on the active loo[.
https://www.youtube.com/watch?v=C65u7Pmz7a0
I think it is a useful demo video, but he does not detail how the B+ is routed around his feedline choke inductors.  He also claims that filtering the USB power to his SDR will not make any difference (min 2:48)...but my experience is using a linear and filtered 5V power source does make a difference with my 5V powered Asus notebook PCs running wsjt-x connected to analog receivers....

W8JI's read on Magnetic Loop Antennas is worthwhile.  http://w8ji.com/magnetic_receiving_loops.htm   I found it interesting he concluded an isolation transformer at that loop feed point for matching and common mode isolation was worthwhile.  That is consistent with W3EEE's read on noise management...and my experience as well... http://www.hifidelity.com/w3eee//Noiz%20.html    

Finally, the web page 
https://sidstation.loudet.org/antenna-theory-en.xhtml

shows the math for how effective loop height has an effect on antenna performance, which in part is a loop-turns thing.  But this read seems to treat a loop antenna as primarily responding to magnetic fields only, and we know this is not the case as the loop responds differently to near field and far field signals....
Anyway, that is my 2 cents on the subject....
73 Mike wa3tts

-----Original Message-----
From: N8OOU <n8oou at meekfarm.us>
To: lowfer at mailman.qth.net
Sent: Sun, Mar 13, 2022 3:04 pm
Subject: Re: [Lowfer] Loop antenna question

JB,

Your question got me wondering about the answer. I don't have an EE 
degree, so I can't contribute information based on knowledge or experience.

However, I do have yard space, a 100Ft length of wire, and the balun I 
used the last time I played with a LOG (Loop On Ground) antenna. It took 
just a few minutes this morning to gather those components and put the 
LOG back in operation.

I used my KiwiSDR to get spectrum and waterfall graphs of 0 to 15 Mhz 
using my low noise vertical, a single turn 100 Ft circumference LOG, and 
a 4 turn LOG using the 100Ft wire.

The result: The LNV wins hands down. The single turn makes my Lowfer 
signal stronger than the 4 turn, but the 4 turn makes my local 910, and 
1450 BCB stronger. Interesting....

I have put the screen captures up on qsl.net/n8oou/.

73  de  N8OOU - Mike Meek

On 3/13/22 08:35, Stan W1LE via Lowfer wrote:
> Would be an interesting experiment, comparing the 2 configurations simultaneously.One minor concern may be the self resonance due to winding to winding capacitance.
> I will be monitoring for other's suggestions.
> Stan, W1LE    Cape Cod   FNN41sr
> 
> 
> -----Original Message-----
> From: John Bruce McCreath <weazle at hurontel.on.ca>
> To: Discussion of the Lowfer (US, European, & UK) and MedFer bands <lowfer at mailman.qth.net>
> Sent: Sat, Mar 12, 2022 9:54 pm
> Subject: [Lowfer] Loop antenna question
> 
> 
> 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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