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- เผยแพร่เมื่อ 12 ก.ย. 2024
- The third in a series of videos showing the build and testing of a KK5JY Loop on the Ground Antenna.
In this video we make the loop larger and compare against the original smaller loop with some more on air tests.
Parts 1,2 & 4 of this series can be found at:
• Loop on the Ground Ant...
• Loop on the Ground Ant...
• Loop On The Ground - P...
Paul G1WHP is planning to experiment by adding a pre-amp to his LOG antenna. It will be interesting to see the results...
This is just one of many amateur radio videos on this channel. Please feel free to browse, like 👍🏻 and subscribe 🔔
Thanks.
Ian.
Thanks for the detailed testing and results, Ian.
Thanks James. Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Interesting test results Ian, thanks for sharing.
Thanks! Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Very useful and nicely done. I am about to try it as well. Thanks!
Ok Thomas. Good luck 👍🏻
One thing we're missing from these sorts of experiments are signal/noise ratios. It's less important to me that a smaller loop attenuates the noise more than a larger loop if the smaller loop also attenuates the signal more. Unfortunately most radios don't really have great interfaces for accurately measuring SNR; you'd need to convert from S units back to decibels, and that's assuming the S units are actually consistent...
It's interesting that the two loops in conjunction seem to do okay. It makes me wonder if there's such a thing as a "fan log" with a bunch of lengths for different bands, hoping to get some rx resonance on the best-fitting loop for a given band.
Yes. The SNR is key as you say. I’ve kept using this loop for some years now and it works well in its original form. Lower noise and signal, but better ratio in many cases 👍🏻
Very interesting Ian. I found similar signal-to-noise benefits on the higher HF bands using my 80m TX loop antenna @9m elevation for RX.
I will try the loop on the ground next having watched your series of videos. 73 de Ady G6AD
Have fun Ady! Nice to chat with you yesterday 👀
I stumbled upon this LOG vid series....thank you so much, looking to do one for 80 meters
73 de AC3LZ
Great! I use it on 80 and 160 all the time. It’s my right ear on the dual VFO 😀 Part-time use on 40 as I have other options on that band. Have fun!
good stuff ..
very well done
73 sam
Thanks Sam!
Very interesting. I built one, quarter wave on 80m but I had poor results (couldn’t beat the dipole).
Having watched these videos, maybe I’ll try again!
Ok Roberto. Good luck 👍🏻
Candidly, I thought this might be a complete disaster, but it does have merit, got a bit fed up with noise levels on 40m, seemed to put out quite an exceptional signal but ludicrous noise levels were killing my receive. I might just have to try similar. I know a very low wire was useful on 20m receive. With stereo headphones fed from main receiver and sub receiver the “diversity” from separate aerials was amazing.
Yes stereo and two antennas is a good experience! Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Thank you Ian, very interesting :)
73s John
Thanks John. Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Thank you Ian. I went a built a small loop after watching your first video. I had the same initial disappointment you did.
I think the key here, as with beverage antennas, it receives surface/ground wave as opposed to skip. From my research a dipole doesn't emit/receive much surface wave while a vertical does. I'm going to do more testing but here is my hypothesis; it will be better suited for closer stations that might normally skip over you.
Vertical antennas radiate a decent amount of surface wave, the lower the frequency the farther the surface wave will travel. This is why the higher bands don't seem as good but I'm betting if they were closer it might be a better antenna.
You might be into something Levi. Good luck with your experimenting 👍🏻
Thanks for this!
My interest is with the 160M band only. Today I installed a square LOG, 55' on the sides. Works well on 80M but 160M DX stations are attenuated too much to be useful. I have the property to make it larger, but it appears that this may increase the background noise. I may try a preamp first. Prior to this I tried a 200' BOG pointed to the EU and found about the same performance on 160M.
Ok Rick. I saw the noise go up with the size of the loop too. Good Luck!
@@ianxfs I modeled this with EZNEC 6 to confirm kk5jy's plots. Then lengthened the wires to compare the gain at 6 and 3 degrees. The larger loop increased the gain significantly but the gain peaks at 60 degrees. Two bad we cannot steer the loops peak elevation angle like EZNEC. Good thing the investment is small, the results may match the costs.
Thanks Ian! Appreciate the video. De N9NY
Great!
Good job +++ :-)
Thanks Greg. Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
I think that’s been a worthwhile experiment Ian,now did yo try the feed point in different positions?i heard the loops might have some directivity ?
Gm4zji Yes, I tested when in the bottom-right corner, but eventually settled for top-left. That was a decision purely on direction of theoretical propagation though. It would be tricky testing directivity unless you’ve got a patient station to test loop rotations with, or you’ve got two and can toggle between them. If you check out the first video (this is #3), I explain the directivity. 73. Ian.
ianxfs thanks Ian enjoyed the experiment👍
Correction to the above. I tested both bottom-left and right. Went with top-left for the final set-up, which is effectively the same as bottom-right, for the propagation as above, but also to get the connection box off the lawn and into the flower borders out of the way.
What about the conclusion for best height of the LoG above the ground. Did you found the best height or it does not matter? Thanks. Petr
Hi. Yes, on the ground as per part 1 of the video series. I’ve used it ever since 👍🏻
I wish someone would do a proper S+N/N measurement in one of these vids.
Hi. Have a go 👍🏻
Nice work Ian. I will continue experimenting including the LNA at the feed point. On another point I noticed your ALC was set at AUTO FAST. Mine goes though FAST - MED - SLOW - AUTO SLOW. How do you get it to AUTO FAST. Paul
Ah ah I was talking AGC not ALC but I have worked it out by watching the video again. It goes to AUTO FAST on CW by default. When I first watched I thought you were still on LSB. 😜
Ha ha, yes! Apologies for delayed reply Paul, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
What if you added a low noise amp at th loop antenna it should do better with the signal strength . Or a larger wire diameter for the loop. Just wondering
Chuck AA4CP Port Salerno, FL
Thanks for the observations Chuck. I’m still picking up background noise on the rig, so I’m not expecting much from a pre-amp (which again I can engage at the rig end if I need to). Paul (G1WHP) was going to try a pre-amp, but I’ve not heard back from him yet. On the wire front, I’m not sure that will make a difference? I’ve already tried thin telephone jumper wire, up to the much thicker DX10. 73. Ian.
The LoG does not respond well to high angle incoming signals. . High angle signals on 160 and 80 mixed with high angle noise will not show much improvement in SN Ratio on a LoG because the loop rejects the desired frequency by the same amount it rejects the noise. On 40 the lower angle skip signals will show significant improvement in SN Ratio over the higher angle noise, as you saw.
Mistaking louder signals in the speaker as the criteria for judging improvement leads to questionable conclusions. If the reactance of the windings is not at least 4 times the impedance of the loop, results will be poor.
K8DO / Doc
Thanks for the observations Doc 😀
Callum, has a point maybe LNA?
Paul, somewhere else on these replies, is going to try an amplifier on his, so watch this space.... Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Very interesting Ian, seems it's good for QRN/M of some sorts, but was most interested in the 160m beacon where it didn't seem to distinguish S/N. Good on 80m as you say and would be a useful option to try (and cheap) for anyone suffering from QRM on 80m. Thanks for the inspiration to do it and I have the bits on their way here to try my own. Cheers. Tom M0RMY
Thanks Tom. Yes it works for me on 80m. Apologies for delayed reply, I've just discovered TH-cam holds a folder of what it thinks is "iffy" comments...all mine seem ok though, so not sure why!
Hey. Can You tell me what diameter of copper wire is necessary for LoG antenna? I can either use wire from unused UTP cable i have laying around somewhere, or do i need to buy better copper wire (thicker in diameter)? Thanks!
MrKeczub Hi! I think any wire will do as long as it’s insulated. Mine was domestic 0.75mm twin mains lead, but it was just what I happened to have to hand. Good luck! Ian.
@@ianxfs Thank You!
The reason people struggle with this antenna is they struggle with understanding Matt’s instructions on the set up of the antenna and radio. As Matt said the antenna set’s the noise floor NOT the receiver. Otherwise it’s useless because all your doing is increasing the noise floor which defeats the original design. Same thing with bog antennas as well!
Hi Ron. See my part 4 comment. Thanks.
A LOOPANTENNA HAS TO BE DC GROUNDED OPPOSITE THE FEEDPOINT TO A METALSPIKE
DRIVEN INTO EARTH!
SUGGESTED HIGHT 10-20FEET!
It doesn’t appear to in this design 🤔 Thanks.