Wire loop on the ground for HF receiving: How good?
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- Опубліковано 5 вер 2024
- A wire loop on the ground as a receiving antenna? How well does it work? Here I give it a test. FRONT socket connected to wire loop, REAR socket connected to G5RV. Read what others have done here: www.kk5jy.net/LoG/ & swling.com/blo...
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👍thanks for demo. I was a little surprised that your loop didn't have a more dramatic effect on noise. The only 80m antenna I currently have is an inverted-L. On TX, it gets out around EU OK but useless for DX. On RX it is very noisy with S7 to S8 noise typical and doesn't hear much DX. So, one afternoon, I quickly put up a temporary 80m end fed dipole just above ground on 2m poles. The 40m of wire was in a near perfect square with the ends close together (approx. 1m). It certainly dramatically cut the RX noise down to S1. However, I suspect the radiation angle was very high. Certainly good for NVIS though as I worked a G-station a few hundred km away on SSB with 5W QRP. I should have left it up after dark when 80m DX opened to see how it performed - that was the plan. However, XYL pressure was exerted to remove the offending poles and wire from the lawn 😔. Not a proper loop of course, just a low dipole in the shape of a square loop but it certainly worked.
Maybe look at trying a mag loop
@@MidlifeRenaissanceMan , thanks. On the list of things to try is an active RX loop for HF and maybe an 80m/60m Small Transmitting loop.
I have gotten good results with my EFHW after viewing Steve Ellington's videos where he measure RF current for various configurations.
One of the configurations produced 33% more RF current on the antenna wire than other typical installations.
One of my playlist "Technical Presentation" has it as the second video.
Ellington has two videos of the test. One is the actually test which is long, a bit boring, and harder to follow. In a second video he distills all the info into a chart.
Second video by Steve Ellington will help optimize an EFHW inverted-L.
ua-cam.com/play/PLJtn8QaWqfA7-3RIHbxFWiW7rEZmC0Tsk.html
Hi Peter. I have been experimenting with the ground loop antenna for about 6 months and I have found the transformer has to be wound in LITZ wire.
The wire can be used from an old ferrite antenna in a portable transistor radios 20-30 years old ,it is cotton covered multistrand wire and when wound on a ferrite core it increases the Q by a factor of 50.
Also I put a gasfet amp in a plastic zippy box with a lithium cell @4v =35db gain .06 NF from an old sat convertor the amp only draws 5ma and lasts me 4 weeks with an on/off SW on the zippy box.
Well it works better than my trap 5 band vertical on 40 MT signal to my QTH in QLD from SA 5/5 when I SW in the ground loop with amp 30 over 9's some times I have to use the attenuator on my I-COMM 718 so it does not overload the front end ,it seems that galactic noise is my only issue now and a strong stations nearby.
So in closing I would recommend building a small preamp on Vero board and on a plastic Jbox from Bunnings/stripping an old 20MT extension lead for the ground wire any colour you prefer.
Now this is important use 75 ohm quad shielded co-ax to feet the Jbox to reduce common mode noise (weatherproof one ).
I had noticed a lot of noise on Peters rig on the ground loop ,the secret to low noise is to have NO earth connection between the front end of the loop that is why Input of the transformer of the amp in the zippy box separate to any ground or earth potential.
Final note to Peter and anyone interested I will make up a pdf on the construction of the amp and the antenna SW box for Hams that don't have dual SW antenna ports.
Please be patient as I am a retired electronic tech and I will respond to all you emails in due course and send you my Free e-book "secrets of eliminating RF noise" .
Foot note _My next project is to make the loop tuneable/resonant with varicap diodes array (May have to manually tune it at the zippy box for no common mode interference) also I forgot to mention that I can pick up the heterodynes on 11mt CB band every day as well as most of the 10mt beacons as well.
E-mail is vk4zow@gmail.com
Hi bob, why would using litz wire give you a higher Q? I’m surprised at Peter’s poor results. Just seen Roly ZL1BQD’s ground wire that goes all round his house, he seemed to get excellent, almost dramatic results. I’m using 4 to 16 turns on a T43 toroid, I’m going to see if it helps improve noise over my EFHW on 40 this evening. Next is an LNA if I can see a noise improvement.
@@cthoadmin7458 Hi ctho admin
From my observations the reason the Litz wire is used on transistor portable radio's antennas are because of the high Q and it helps make the feritte rod more sensative when tunes to a certain frrequency.
So knowing this I wanted the torroid core to be able to have a high Q like the feritte rod.
Now I have improved the Q of the antenna by using a dual ganged variable cap (out of an old radio) so I can manuly tune the loop at it's 600 ohm feed point.
I have found that the loop is acting like a magnetic loop when tuned to the frequency you want ...A note It only tunes down to 80-160 not up in FRQ if you want higher FRQ you have to make a smaller loop say for 10 mt then tune down.
As the ground loop works on the F layers a very low noise amp is a must.
I fabricated an amp using a BFR 988 mos fet in a isolated zippy box isolated from any power from the house or the shack by using old lithium cell with a USB charging port on the side (1 amp diode in series with the cell for charging ,with a red led as a indicator) a full charge last me 2-3 weeks switch on all the time.
@@bobmurton5869 Thanks Bob, very useful info, i'll see if I have an old Litz wound ferrite somewhere and use that. Lots of experimenting... Tim VK4QP
Great demonstration! Built one for 160 mtr. Used 15 feet per leg. Trying it out tonight for first time. Stay safe. Thanks de N9NY
Hi Peter, a while ago I did the same tests, the noise caused by appliances lowers a lot, with constant noise s9 + 10 low to s5 the agc and audio readability work better, I could maintain a qso if I change the antenna when transmitting
An improvement could be had by using miniature coax without the shield to reduce common mode crosstalk from the primary to the secondary in your binocular transformer core. It reduces the capacitive coupling between the turns.
2:46 from the manual: "The IPO feature bypasses the receiver RF preamplifier, thereby eliminating the preamp's gain. On the bands below 14 MHz, the input preamplifier is rarely necessary, and activa- tion of the IPO feature will provide substantial protection against intermodulation and other problems associated with strong signal input to the receiver. Rule of thumb: so long as the S-meter is moving on background noise, additional front-end gain is not necessary." and ATT: "the Attenuator will reduce all signals (and noise) by 10 dB, and it may be used to make reception more pleasant under extremely noisy conditions."
Loop may be “no better” but it is a LOT easier to deploy for monitoring purposes. Would a low/wet/costal placement improve S/N ?
The G5RV ....was my antenna as a lad! Awesome antenna....used a tree on the golf course...Auburn Council was OK with it...those were the days!
Hi Peter - I had been hoping you would feature a "Loop On The Ground" receiving antenna on one of your vids. A nice surprise to see it! A few months back I played around with one of these for about a week and I came to just about the same conclusion that you did. When I first was preparing the antenna I was really hoping it would work better than it did because I am in an unbelievably high noise environment here. I have to say though, I wasn't too shocked when I saw how it really worked. You're right it is kind of surprising that it even works at all. Probably useful in [extreme] stealth antenna situations. Cheers - de WB8YMV
Thanks Mark. I think it would be great in small lot circumstances. Where you can only put up a vertical (noisy on rx but OK on tx) but might be able to put down a loop on the ground for rx.
Not enough land there plus too many close houses but if you have a couple hectares maybe a Beverage Antenna would work well. I know it would work well with a few acres of land because for years about 15 to 20 years ago I was using skywires of 500 to 2500 feet through trees in my rural location but I also put a 500 foot beverage on the country land that family lived at and would pick up all kinds of SW stations from 1993 to 2007 at that place. Not to mention verified over 150 countries on shortwave until sadly some of them no longer transmit on shortwave. Was a cool experience and also doing some HF contesting from that location in later years.
Over the past number of years stuck in this flat I've only been able to use a longwire and have had some pretty good results with it, it's literally 30 feet of speaker wire and I'm getting stations from all over the globe my main rx are from uk/Europe , north central and south America these are pretty reliable and occasionally Australia on a really good day usually 3/5 can be better can be worse, thanks for sharing another great video mate, 73's MM7BXH Rab.
Any operators from anywhere near coffs harbour ?.
With that did you use any other components like loads, transformers or coax with a certain impedance
Can't watch the whole video now, but looking to returning to it!
73, Matt M0PTO
Simple experiment but very interesting.
I've been thinking about making up a loop like this for receiving and connecting it directly to a radioberry connected to my home wifi so I can listen to it on the computer in my office while using the other radio connected to my G7FEK. The trick is going to be some protection for the radioberry when I transmit on the other radio.
I've run very low dipoles on 20 MTRS , No more than a mtr above ground , The noise was very low and I still managed to work Europe with respectable signals from here in Wales .... Gw0wvl 👍
Signal to noise ratio really plays a big part in radio listening.
Nice experiment 👍👏👏
Sometimes it doesn't switch correctly between front and rear connector. Press PTT for short helps.
To compare logically wouldn't you need another g5rv on the ground?
I have found the loop on ground is ok. But I have hardly any noise. I found the noise around Currum is loud. I have tried setting up near the Patterson river very noisey. Maybe the train line?
I can see 2 differences between them, one can transmit and the other can't, and one is much more stealthy.
Did you know the russians used _underground_ antenna's in the WW2 war?
I’ve heard of attempts using ground stake antennas used to pick up VLF signals.
@@MidlifeRenaissanceMan Lots of information about underground antennas: www.antentop.org/book/c_underground.htm
Hi Peter, I built one last year because of the high noise I was getting on 80m. I documented the build and brief test here: ua-cam.com/video/uQUiPHwStcY/v-deo.html
I found that it DID make quite a difference on 80m and to a certain extent 40m. I used a different impedance matching ratio to you. It is amazing what a loop of wire on the ground can achieve though isn't it! Thanks for your great videos. 73 Nick M0NTV
Not to be confused with a ground loop.
I have one of those in my home studio. Also, if I have bare (bear ?) feet on the wooden floor, I feel electric shocks when I touch earthed metal appliances.....haven’t finished the wiring in that part of the old house.
73,TA4DA
That is the DIRTIEST FT-817 I have ever seen!
🤘
Certainly a bigger deal that I think most realize.
clean your radio 😃
🤣
peter cut that loop in half, earth the hot end piece with 470 ohm +_ and throw the other halve in the box for another day.
:) Mine is a 60m piece of wire strung 2m high, 9:1 fed and earth at far end through 470 ohm, now that works, the loop ? nah its a waste of time.
it's not a waste of time -- in my and many others' environments it has made a dramatic difference in signal:noise. If it didn't in yours, fine, but don't assume and claim it's a waste of time for everyone. The KK5JY LoG can work very well indeed.
GET so TIRED of nothing BUT NOISE!. White noise....Squealing...The hobby is a waste of time half to 3/4s of the time even for simple listening! (AND people "believe" this will be helpful in an emergency!...BAAAAH!)
A lot of the trash you will hear including squealing and other noise is basically common mode noise where noise from electrical sources, computers, TVs, appliances end up on your feedline and go back into the receiver. The best thing is to get your antenna outdoors and as far up as you can into a tree or at least somewhere where the coaxial feedline isn't pumping common mode trash back into your radio. Another way to do this is making or buying a common mode choke or using ferrite rings or ferrite chokes to knock out as much of this unwanted trash as possible. Another method I have been working with myself was building magnetic loops for not only HF bands like 80 meters, 40, 30, 20, 17, 15, 12 and 10 but to also use a noise reduction device like a Timewave device ANC-4 where you can reduce the overall noise. Prior to doing this I regularly on 20 meters had an S7 to S9 noise level. Doing all of these steps which cost me a few hundred dollars for the ANC-4 but also the ferrite on coax has now reduced my usual 20 meter noise level to S3 or S4 not terribly ridiculous when a lot of the times the natural noise floor is S2 sometimes S3. It's not perfect but its better than letting this noise trash dictate when you are going to operate etc. Even better is if you can get a few miles into the country where there is far less interference. I hope to be doing that in the next year or two to move someplace without any urban noise issues a maybe 3 to 5 acres of land. Many years ago I lived at a similar place and my noise level was virtually nothing and the noise floor was the standard S1 to S3 at most except for thunderstorm crashes in April through September. Which was mostly a problem on 160 meters, 80 meters and 40 meters. One item I would stay away from the MFJ 1025 and 1026 Noise Reduction modules. IMO they are pure junk and very difficult to get to work as noise reduction. I've had an ANC 4 going back 20 years and at one time lived in an urban apartment where the noise level was usually S9......using the ANC-4 cut that noise level just about in half and I worked over 100 countries on an indoor wire antenna wrapped around the walls of the room using cup hooks as supports several times. 100 countries on SSB not bad. Good luck to you.