About Radio 67 Magnetic Loop Antenna for 17,20 and 40 metres

[@CB-RADIO-UK]

Wow what a view you have Andy. I could sit there all day. Thanks for the video, very interesting. Thumbed up.

[@AndyDaviesByTheSea]

Hi Dennis glad you liked the bayonet fitting. I didn’t have the pin through to start with and it all flopped about all over the place but now I’ve got it nailed. All the very best ... Andy GWØJXM

[@AndyDaviesByTheSea]

Hi Leonard, well I reckon it’ll work surprisingly well if you can get it by a window. The very first time I connected this to my transmitter was in my workshop where I have a lot of metalwork and metal cabinets. I had several DX QSO’s then it dawned on me that, not only is there a lot of metal work in the room and I mean a lot, but when I built the workshop I insulated the walls and ceiling with overlapping aluminium coated foam board, so it's almost a Faraday cage! Kind Regards ...Andy GWØJXM

[@celtichongy]

Another good video Andy, thank you. You and AA5R should get some recognition for the excellent contributions you make! A few other good guys too.

[@AndyDaviesByTheSea]

Hi Mark, thanks for the feedback. The nice things about loops are, they are small and work well at just above ground level. Watch out for the high voltage. There are some good sites with voltage calculators, they don’t all give the same result but I guess they are near enough to let you know when you’re heading for trouble. Good luck with the project. 73’s Andy GWØJXM

[@F8FCA]

congratulations Andy Your magnetic loop indoor it' s just crazy what a performance ! Wow wow wow !!! 😮👍

[@HugDeeznueces]

Impressive project and outcome. Thanks Andy! I will have to copy some of your details for my mag loop. Thank your for sharing!

[@AndyDaviesByTheSea]

Hi again what I didn’t say earlier is that if you can mount the loop high enough that you might find that you can mount it horizontally and you should get an omnidirectional field pattern, one other point with any antenna in your loft you do run the risk of coupling RF into the house wiring. I did it once and I damaged a computer as a result. Man I'm still learning. All the best ... Andy GWØJXM

[@johnwilson3918]

Thank you Andy - this has certainly inspired me to do some more research into using a loop.

[@Dazzwidd]

How did you go? My investigations have ended up with me at the hardware store looking at aluminum strip which comes in 3m lengths. Much lighter than copper and if you use a piece with 25mm width or more, it's going to have a very low RF resistance. I'm about to make a loop out of some

[@giorgionapolitano5861]

Nice job Andy. In our club station have a little model for 20 meter. Now the new project will be also for 40 meter band. For the capacitor tuner i'm planning a loopback control with a potentiometer on the mechanism. Congratulations de IZ8FAV

[@AndyDaviesByTheSea]

Well done 73's ... Andy

[@wharfrat5564]

Very nice video Andy. Your ant design is nice and a great idea for people with limited ant space or restrictions.John

[@faustdownunder]

Nice work. The thin wire connections from the variable capacitor can be a real Q-killer. I would change replace them with metal strips or coax braid. I would not use thread connections. No defined RF current path. The overall construction reminds me of an article I wrote in 1982 in the German CQ/DL magazine.

[@AndyDaviesByTheSea]

Hi, OK on the 'add-on" co-ax capacitor one could reduce the losses by going to strips of copper but take another look at the copper strip that connects the variable capacitor to the loop. The physical thickness of the strip is many times thicker than the skin depth of the current at the chosen frequency, also note the orientation of the strip is such that the current flows in the broadest possible amount of copper. (The same can be said for the plates of the capacitor) Even so, in reality the current tends to migrate out to the outer edges of the strip, this is due to the self inductance of the strip. I guess the real winning answer would be use litz wire. I wish I had more time to talk about my experiences with high power Radio Frequency power transformers and induction heating feeder systems up into the 100's of KW range, all very interesting and sometimes a bit scary! All the very best . . . Andy

[@faustdownunder]

@@AndyDaviesByTheSea Oh, I see. In the video it looked like thin wires. I use 3D EM simulation (3DS CST) for decades now and I have often seen current distribution on metallic surfaces. In one planar wideband antenna the "migration of RF current was so strong, that the middle part of the antenna could be punched out without any effect on the antenna properies. In smaller strips however, current migration at HF frequencies is probably less. I find that the key to making good magnetic loop antennas lies in conductor surface area. In this context, it is important to realise that tubular loops leave the entire interior metal surface un-utilised.

[@dennisqwertyuiop]

Great design gave me idea how to stop pipe from turning w/nail your solder job is better than some plumbers Thankyou Andy Dennis Wis

[@AndyDaviesByTheSea]

Thanks, the QTH is great until the wind blows, but I guess as with any QTH with an open view anywhere that’s when you pay for it. We routinely get winds into the low eighties (MPH) and as there’s nothing to disperse the wind it can be pretty destructive and very noisy especially in the middle of the night. The greenhouse and sheds have to be fixed to the ground with substantial steel cable and galvanized steel land anchors. Kind Regards ... Andy

[@donniebrugge8117]

Andy, nice job. anyway to get you to post a little drawing with size of loop etc? thanks Don

[@Endogamy]

This is a well made loop antenna, thank for sharing. (That petrol money does allow people to reason, think and invent.)

[@richards779]

Innovative way the loop connects, great for portable work (:Seen a jennings 0-500pf 15kv capacitor for sale, think i might buy it now a give a loop go (:

[@2e0lgz]

Looks great andy and well made well done great video

[@Satchmoeddie]

Yow! I will need the 5KV Comet vacuum cap! What if i can make it a circular loop, with larger tubing? I sure appreciate the information! I want to be able to do a kilowatt with a loop. Beautiful workmanship, mate! Nasty looking bruised thumb, though! 80-100 watts is "barefoot" for me. I can drop to 5 QRP. I have taken to using a lot of acetyl plastics like Delrin. I repair guitars, and amplifiers. Delrin is nice stuff for clamping up guitars for repairs, as most glues will not stick to it, and it is really tough, durable plastic, that does not get brittle with heat and age. Delrin is fabulous stuff, although a tad expensive. Try finding a shop that works with Delrin, and get some scraps. I think you will like the stuff a lot! I at least want a directional loop for receiving. I will probably utilize a simple noise bridge for tuning, until I get another spectrum analyzer I can run off a T pad. Cheers, 73s, KI7AQJ

[@AndyDaviesByTheSea]

Hi, I wish the band had been properly ‘open’ but I’d been wanting to finish the video with a demo and QSO and there hadn’t been any activity on the band for a couple of days (at a time I could fit in) so when I heard 9K2UU I gave him a quick call. It’s not the best demo in the world and my operating procedure went to pot, I didn’t give him his report. But it’s good to think that some old copper pipe has been put to good use. I like QRZ . com as it opens up another level of interest 73's ...Andy

[@zaperfan]

You have inspired me to make this magnetic loop .Not for transmitting but to null local plasma TV interference have you any suggestions about capacitor value i would appreciate it .I watch all your videos and just love your passion for radio.Keep them coming .PS i have broad band plasma interference across most of the HF spectrum.

[@michanoymark2109]

Beautiful project! Everything is detailed, but the length of the copper pipe was not mentioned? Or did I not follow properly?

[@rajeshhuddar3470]

One more question , may I request for the details of the gama match, length of the copper rod, distance from the pipe of the loop. The height at which the SO239 has to be fixed.

[@AndyDaviesByTheSea]

Hi essentially the loop antenna is good for any frequency but the size of the loop and the value of the capacitor has to be correct for the chosen frequency. To help you I’ve just added a link to a very good site where you can get all of the dimensions for your chosen frequency. The link is at the end of the description box for this video. Be aware of the very high voltages developed on this antenna + Check that the loft doesn’t have aluminium foil in the insulation, could act as a screen.

[@andrzejpl9897]

Very nice video Andy . Thanks .

[@hitry2]

Nice video and great antenna project. I really like the QTH!

[@AndyDaviesByTheSea]

Hi Rick It was at about 45° to his bearing, that is neither broadside nor end on. What I’ve found is that the loop’s not very directional at all, I suspect that’s because I’ve only ever used it in a relatively low position. In the video the loop is on the wooden floor and the true ground is just over three feet below the floorboards. I’d say it performs a bit like an inverted ‘V.’ I guess you’ll have used loops in the air force, are they directional with real height? 73's... Andy GWØJXM

[@atticman2011]

Great Video Andy, Well Done.

[@AndyDaviesByTheSea]

Hi Cor, if you pull down the ‘Show more’ box under the video you’ll find the dimensions there. If there’s something I’ve missed please let me know. It’s just coming up to midnight here right now otherwise I’d go through it and double check, but as I say let me know if you need more information Kind Regards ... Andy GWØJXM

[@mallynero]

Excellent video great antenna can't wait to build one thanks Andy 73..

[@jackrippah]

Thanks for the video Andy. I've been thinking about making a loop myself. You've provided a very interesting and useful practical 'How to' on loop antennas for a little bit of power. Super quality workmanship on your antenna by the way. Vr 73 es aloha! wh6ajm

[@AndyDaviesByTheSea]

Following on from my previous comment below... by the way don’t forget to watch out for the very high voltage on the antenna !! Kind Regards ... Andy GWØJXM

[@antennebuis]

Thx Andy,hope to work you have a lott time for you loop testing 73, de ON3MK

[@control5835]

May I ask, is it a common misconception that loops like this are very good at nulling out QRM if orientated properly. Brian M6BAQ

[@johnpeterson7264]

Great presentation. Thank you.

[@Dazzwidd]

I shared this video a lot in the last year or so. It's views appear to have soared. 😀

[@AndyDaviesByTheSea]

Thank you very much I'd love to hear from anyone who has copied or improved on it. Kind Regards . . . Andy

[@Dazzwidd]

I don't think that anyone is going to improve it much. You took quite a few measures to ensure good performance without going to the ends of the earth. The only thing that would improve it would be a vacuum variable capacitor, but I suspect that even this would not make a massive improvement. I have been Looking at aluminum strip at the hardware store that comes in lengths of 3 meters. I was going to use the one that is 25mm wide, use an aluminum angle at the bottom for an SO-239 connector, and maybe use aluminum sheet to make some capacitor plates and use plastic toilet seat bolts, as I have some) for the adjustment. I'm still deciding on the capacitor- I could even use blank pcb material, not 100% on what im going to do. I still won't be improving upon your loop (more like dropping some performances) but it will be smaller and lighter and also be able make it able to be easily disassembled.

[@Dazzwidd]

Hi Andy, you have done a great job engineering this loop, no chance for any significant RF losses and simple. I love the disassembly aspect of it too. I was thinking, on 17m, at its highest frequency of operation it would be more or less a halo antenna standing vertically. It only has 4.9pf bringing it to resonance and is not greatly shy of having a 1/2 wavelength perimeter. Have you checked it's self resonant frequency with all the capacitors completely unbolted? I'm wondering if it makes it to 15m. I'm thinking of making one which is self resonant at 27mhz and using a variable capacitor to tune it down to the lower HF bands but I'm not sure how long the sides are going to need to be to achieve that. Anyway, thanks for the posting Andy, it was interesting. Best regards :)

[@ve9aas198]

Hello Andy I am avrelatively new ham and will be operating QRP max 15 watts. My mode of operation will be CW with some phone USB/LSB. Any best guesses how the mag loop might perform for me. I assume your installation is for demo/testing purposes. XYL may not like the experience of four or five KV coursing thru her body should she come in contact with the loop mounted on your nice rail hi hi.

[@control5835]

I might make one for RX only, would you know the approx change in capacitance pf, required to tune from 7.1MHZ to 7.2MHZ please?

[@AndyDaviesByTheSea]

Hi there, if you pull down the ‘Show more’ box under the video screen you’ll find the details of the capacitor that I used. Good luck with the project. Kind Regards. .. Andy

[@AllAmericanFiveRadio]

Hey Andy, Very nice demo of the antenna. Tuned loop antennas are surprising. Was one side of the loop pointing in the direction of 9K2UU? And how direction is the loop? Regards, Rick

[@st2nh]

nice vedio OM., thanks for sharing

[@danmyself5341]

I saw that you put your loop antenna next to you I was wondering if you had any concerns about EMF exposure being so close to your antenna while you are transmitting 100 Watts

[@AndyDaviesByTheSea]

Hi Dan that's a good question but no I didn't give it a second thought. I only did it for the video. Given the inverse square law I was probably at higher risk using the old style mobile phones that we used to hold next to our heads. But having said that I don't think that I would want to spend too long too close to any transmitter. I think that in the future they will look back at mobile phones and tell us that they're as bad as smoking was, but maybe we'll need a lot more data. I think trying to get folks to give up using their phones would be harder than getting them to give up smoking. Everyone seems addicted to their blessed phone these days. All the best. Kind regards . . . Andy

[@wf2v]

Pretty neat. How well do you think this would work in a hotel room where there may be steel in the walls?

[@AndyDaviesByTheSea]

Hi there, I think so too but apparently I'm going to get my reward in heaven (if they’ll have me.) I must admit that I do like to hear that folk get some pleasure from my efforts and it’s great when someone tells me that they now understand something as a result of something I’ve done or said. I get a lot of pleasure out of KZbin so it’s good to put something back in the system. Kind Regards ... Andy GWØJXM

[@samuelsmith6573]

AndyDaviesByTheSea trust in Jesus Andy! He's our only hope sir! Best 73!

[@corblaak8051]

Do you have the demensions also in metric system Andy, thanks in advance

[@elanpaim33]

great info but can you send the info size please ? thank you vy 73 ep

[@TheLightningStalker]

It's a shame the compression fittings are going to all steel now instead of brass.

[@AndyDaviesByTheSea]

Hey no worries, I hope you found what you wanted? Kind Regards ... Andy GWØJXM

[@rajeshhuddar3470]

Will it be ok to have a square loop instead of the gamma piece. There is a field day coming up and would like to build a square loop antenna like yours.

[@AndyDaviesByTheSea]

Hi so long as it matches the transmitter it doesn't matter what shape it is but but I think you're going to need the gamma capacitor to achieve the match. Good Luck . . . Andy

[@rajeshhuddar3470]

Thank you.

[@mark33545]

How to solder copper pipe

[@corblaak8051]

Verry nice job

[@AndyDaviesByTheSea]

Thank you Kind Regards ... Andy

[@transformational-education]

Nice to see. Thank you.... K7AA

[@kb0roc]

How did you calculate efficiency for all the bands?

[@AndyDaviesByTheSea]

Hi I found a really good loop antenna design program on the internet, can't remember where but it was from a sensible site with good technical by someone who with a lot of working experience. All the best . . . Andy

[@AndrasBato]

Very well done Andy! Impressive video indeed. GL de HA6NN Andy

[@AndyDaviesByTheSea]

Thanks. Regards ... Andy

[@AndyDaviesByTheSea]

Thanks Mark All the best ... Andy GWØJXM

[@mark33545]

Sorry that was supposed to be a KZbin search lol.

[@markbatten5178]

Nice Loop sir! Thanks for sharing. KC9AIX