Re: Experimenting with Loop Antennas
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Roland: You've opened up a very large can of enigma. We made many tests with multiple loops some years ago. Not long into the experiments we realized how complex the study would be. Considering all the factors of wavelength spacing, phase mixing, natural and harmonic resonances, azimuth lobes and nulls, self-resonances, etc. If I can find the file, I'll post some scans on the group's files section. A good place to start was some of the formulas and Theory of Ops found in the ARRL Antenna book. It's a great reference, especially in not repeating some of the mistakes of others. We standardized on the Pixel Pro for the twin loops (Receiving only). Our first tests were using AM B'cast stations with known signal strength (from an omni vertical pole 62 ft tall and bottom fed). That remained our baseline standard for stations all around us. I can't give you any real tech help since so much results from all the iterations. I'd suggest you make the boom adjustable for loop spacing, a phase reversal switch and an adjustable combiner to mix and match the signal levels between A and B. The humor of all this cut-and-try activity was the customer ended up deciding on a loop of our design (30kHz-7MHz) which was just a single turn, 1 meter dia, feeding a ferrite balun (49:1) to match the loops reactance as it varies with frequency. We finally decided to not use a differential preamp, but went into the balun balanced and grounded one leg of the high side (output) and fed the preamp as single-ended. The preamp's output was an emitter follower for 52 Ohms. So, that's a lot of words with no specific help, but I hope it helps you sort out all the possibilities. Stay encouraged to experiment. Bob, N1KPR AmComm/Dynametrics
Engineering, where enigma meets paradox
On Monday, January 20, 2025 at 09:42:54 AM EST, Roland via groups.io <roland@...> wrote:
Hi, I am a new member of this group. Callsign HB9VQQ.
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I have been experimenting with Loop antennas for some time. I have been using a Wlelgood 3.1 loop with a diameter of 1m (single loop) for many years. When I came across the Mag-Loop calculator, I was curious to see if I could improve my RX with a new design. So I came up with a new design with the main focus of reducing inductance and increasing conductor area.
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I finished building the dual parallel loop yesterday and put it in operation. I am using a Wellgood 4.1 Amp. Wired like this. Should I cross the connections?
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More Info can be found at /g/wsprbeacon/topic/bigger_wellgood_loop/110398954
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So which of the two is better? I use WSPR to compare the decoding performance with my “old” Wellgood loop with 2 RX-888 Mk2 and wsprdaemon. This allows simultaneous WSPR decoding on multiple bands. In my case from 2200 - 40m band (bands of interest).
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This is my test setup to compare the performance
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The results can be seen here (still running at the time of this writing). I am not overly happy with the results, especially with the DX Spots (Distance > 3000km) on 40m.
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I am not sure if my 2 parallel loop design is a good one, maybe 2 crossed parallel loops in the same plane (LZ1AQ) would be better. Also, I am not sure if the Wellgood Amp is well suited for this setup.
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73
Roland
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Bob, N1KPR