HAM RADIO: Building a magnetic loop antenna Part 2...
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- Опубликовано: 26 июл 2024
- So much to do, the construction of a Mag Loop.. Its all been none stop over the past month or two... let me know in the comments below what you want to see me build and I will try to do it. :)
This upload is all about building a MagLoop (Magnetic Loop Antenna) its been a long time in the making but has proven to be worth the wait. this is part 2 of a 2 part upload, in this part I will list all the parts and measurements you will need to copy the antenna you see here..
5M of 22mm Copper Pipe
1M of 15mm Copper Pipe
4 x 22mm straight connectors
2 x 22mm elbows
2 x 15mm elbows
4 x 15mm straight connectors
60 cm of M5 treaded bar
Pack of plastic locking joints
short length of 20mm conduit.
Plank of wood
1 X SO239
1M of RG213 or Ecoflex10 or Westflex 103
Please note, that there is more than one way to build a Mag Loop and I have only shown one such example, the use of PVC for the dielectric may prove to be the incorrect choice (time will tell) and also the type of coupling loop, again maybe a gamma match would be better...
To get notified of the next upload .click that bell and subscribe..
Big thank you to Bryan G4BZU and Dameon Hill..
also www.nonstopsystems.com/radio/.... (Frank N4SPP)
Cheers
Mike M0MSN 
Развлечения
A REALLY GOOD CONSTRUCTION
AND A THOUROUG BUILT MAG LOOP
I AM SURELY IMPRESSED!
GOOD WORK! 👍👍👍👍👍
Thanks Mike. I've built several magnetic loops over the years, for HF up to 2 metres. As a rule of thumb, a loop is most efficient over an octave of bandwidth. My HF loops have been made as squares, and I transformer feed them via ferrite rings. One loop uses 6 metres of 22 mm tube, and it's useable from 14MHz down to 5 MHz. Another uses 3 metres of the same tube and is useable from 30 MHz down to 10 MHz. That loop nets me QSO's over more than 1500 kilometres on 14 MHz using about 2.5 Watts of USB when used indoors. I tried making a loop for 50 and 70 MHz, using about 1.5 metres of 22 mm tube, but at those higher frequencies the ferrite becomes lossy (and hot with only 10 Watts of RF), so a more conventional gamma feed works much better. A 144 MHz loop was tried some 25 years ago, mounted on a hand-held transceiver's BNC connector, at 2.5 Watts. It was 29 cm in circumference, and used a vintage beehive capacitor for tuning. That worked very well; earning much better reports than a quarter wave whip, but, unsurprisingly, the capacitor would flash over if more than 2.5 Watts was used.
Hello Mike. A good idea would be to use a scrap trampoline outer ring as they are plenty of them lying about in gardens. Would make a massive induction Loop Antenna. A proper job. George
Thanks George. :)
It operational. Managed to sort out the SWR and find me feet on that one and tune it in well across the 20mb. Been up at 10ft to start with to test out the remote cap control unit and sort out how to SWR it. Managed to get right down to 1:1 :-). Heard LA beaming north to VK's and them returning. Also heard Cuba calling out to Europe and managed one contact to an Italian, IT WORKS . Tomorrow slap up the telescopic pole from 10ft to 36ft and give proper airing. Next Job is make the bolt on cap and get the 40m side working and once happy, interduce a relay so one can remotely bring it in or drop it out when required. Even an American chap on FB antenna site praised it up as correctly built and he's bloody hard to please being a very old hand in the game for many many years. Thanks again. next job build the 80/40m twin loop but build this one as 80m first with twin 6m circumference loop totaling 12m loop designed for 80m 2E0FEH
Good video.
I built a 20M magloop with a trombone slide tuner but the circumference of the 3/4" loop was a shade too small. I built a motor drive using brass rod (forward and reverse), a control box using an Amazon high torque mini-motor, and an electronics store pot for speed control. I had to add a capacitor, which I made using RG213 and I striped the outer insulator and the shield off, leaving the insulator and the core lead. I inserted this 8" to 12" piece inside an equa-length piece of aluminum pipe to make a capacitor. I hung this in parelel across the trombone slide tuner and was able to get 1:1.2 inside the living room window. The SWR changes with the location in the house. The Q being narrow, it will have to be tuned again when outside but I got a contact from south Ontario into the middle/eastern US. Not sure of the capacitance but it is 'tune by feel'. Cheers VE3PUH
Amazing build. Love the trombone capacitor. Finding a high voltage capacitor is one of the biggest challenges to making an antenna like this.
The small capacitor was drifting like heck, because you have used completely wrong component for the task. What you need is a high RF power stable low loss capacitor. The blue blob is designed to act as an RF shunt (so a parasitic capacitance coupling in a SMPS transformer does not sen RF between the power leads and the equipment body), to be loaded by few mA of HF current, plus guaranteed to maintain 50Hz safety isolation property (it is there between primary and secondary after all). Plus being dirt cheap. The drawback is very thermally unstable material (not an issue for the intended task), with rather high RF losses (assumed as a benefit, as it prevents high resonance peaks from amplifying the parasitic radiation). So when you feed your 10A at 7MHz, it warms up pretty quickly, causing the capacitance to drift away.
All RF suppression capacitors will behave same way, it is not because yours was of cheepeese origin, but because RF suppression task needs different properties than a transmitter antenna tuning.
Great reply many thanks.. :)
Great stuff - at the ripe old age of 66 I am about to start study for my foundation and mag loop antennas have really caught my interest . Thanks for sharing.
Great to hear this, good luck with the studies.
Fascinating project Mike. Being a heating engineer myself I'm going to have a go at this. Love the trombone caps. Thanks
Great build, thank you for taking the time to document your build and sharing it with us. 73s from SM7PNV
No problem 👍
Very interesting couple of videos. I still don't really understand how they work, but I'll learn!
Very nice. I'm a big fan of Magnetic Loop Antennas. Squashing the Faraday loop is really a nice touch for the tuning.
Thanks 👍
Everyone is 5x9 in the magical, fantasy land of ham radio.
Yes magic 🪄
Thanks for making this video Mike, very interesting to follow your journey with this.
Glad you enjoyed it!
Brilliant Mike. Congratulations.
Thank you sir. :) 👍🏻
You do some real cool stuff Mike. Thanks very much for sharing your knowledge. I can't wait to see more!
73 :)
Thanks 👍🏻
Thank you so much for sharing this, it was just what I was looking for. Great job!
You're very welcome!
Thanks for sharing the videos, a spectacular job, you have given me the final push 😃 to make a magnetic loop, 73.
Excellent!
Oh by way when using 20mm conduit use the high impact conduit, it wont need the extra bits on ya 15mm copper pipe trombone to sleeve it out as 15mm just fits inside nice and snugly 2E0FEH
thanks for the tip
Brilliant Mike. I had not seen a driven loop connected to the main loop before. The cap builds are outstanding. 73
Thank you 👍🏻
Nice job Mike, very impressed. 73s
Thanks
Excellent work, spurs me on no end to start on my own.
Go for it Alex
I have watched the two videos,. They are fantastic, they are my best practical reference for Magnetic Loop Ant
Thank you Yasir..👍
A man of many talents!
Thank you for the 2 excellent videos.
Thanks 👍
Very interesting and excellent construction. Top work Mr Mike :-)
Many thanks James. :)
Great to see it alive and working!
Yes, thanks
I watched both parts and not yet taken my foundation course so it's great to know how to make these mag loops bearing in mind the dangers also thank you for a very informative two part description on how to make one ,really enjoyed this presentation "Great job"
Superb project Mike. First class 👍👍👍
Cheers Tim
Excellent videos Mike, Definitely a future project.
Thanks 👍
Well done Mike.
Thanks 👍🏻
An excellent tutorial. Thank you!
You're very welcome!
Great job, very ingenious.
Thank you! Cheers!
Fantastic project Mike, enjoyed watching it. Can't wait to see what you next include to it to make it automatic. Fancy making one myself
Go for it -they take a bit of TLC but this vid series by Mike gives you a lot of info. there is also a good calculator by 66 pacific that gives some good stats. Barnie M7PBX.
Thanks 👍
Such a nice build and glad you didn’t edit out the v.1 blue capacitor as it’s good to see the progression of the project. 👏👏👏
Thank you
Really cool project Mike!
Thanks 👍🏻
Another great video Mike. I like the variety of content of the channel. It has inspired me to start messing around with bits of wire and coils which has led to more enjoyment of the hobby. Keep it up Mate!
Great to hear!
An excellent second part to the build Mike and I like others, I'm looking forward to the arduino build too.
Thanks
I love videos like this. Nice work
Thanks!
Love this. A future PDF construction manual would be stellar. WK4T
PDF.... 👍🏻
Awesome project , I’m still learning about real HF and antennas . I’ve been a Tech several years , but started studying for my General exam last month . I look fwd to doing stuff like this myself one day
Great to hear, good luck with the general. 👍
Excellent job!
Thank you very much!
Very interesting project.. really nice
Valdir Franco 👍👍
KM7P...nice work...
👍Good project, thanks Mike. Some good ideas there. Like the 15mm couplers to make the inner capacitor plates snug, like the use of the block joins and the threaded studding for fine adjustment.
I noted that you squashed the small loop to improve match. I have only made one mag loop so far and I found I had to do the same. Definitely interested to see what you do with the Arduino.
Thanks Steve, a little time away but the Arduino or Pi is coming :) 👍
Thanks again for a very nice project. Have been wanting to build one myself and you provided some ideas that I might use. Have all of the parts to make it. Just need to get along on doing it. 73, K5ZRR
Go for it!
Nice work, I like the trombone idea, and will look at trying it when I build mine VK3HJW
Have fun!
Excelente proyecto y magníficamente desarrollado
nice project like to see the complete construction in part . concept is nice although i've seen a square loop with the same material. Your solution for the capacitor is very nice. Very inspiring..
👍
Great Mike. Looking very good 👍🏻 How about some directivity tests in part 3 perhaps?
Part 3 ?? Cheers Ian.
Nov 94 qst has a nice article on a loop tuning capacitor. Similar to yours. If you havent seen it. It has limit switches also. Gotta build one for receiving soon.
In Radio World There Is No Such Thing As "SHORT" Or "Shorted Antenna" I See Its An Older Video Of Yours, But Trully Amazing :)
Fantastic Build there Mike, I like the Trombone cap idea. I used a big air variable rotary 4 Kw. Add on fixed caps are very handy, liked your idea. mine was 8 x 20 inch lengths of RG213 100 pF. (some folk said a waste of good coax-Lol)
But the best bit was 22mm copper pipe thats a dream. Really enjoyed that build. Job Done, Very Well Done. Barnie, M7PBX.
Thank you 😊
Cheers Mike, may I make suggestion on a little known antenna project you may like to build for the channel, I really rate them , but there is scant information about them- the 3DFL-Three dimensional folded loop-easy for the 2 metre band. it would be a great addition to your antenna build series Barnie M7PBX.
You may have heating of the ceramic capacitor that causes the drift. That small size would not be up to handling any large amount of RF current the would flow through the loop.
It’s witch-craft! No idea how mag-loops work but the trombone capacitor was inspired! Ive absolutely been wanting to build my own and this looks doable
Many thanks
beaux montage et travail très propre merci et 73 qro de la France
Merci.. 👍
Always nice to see a home build. You've clearly hit on an practical compromise in terms of amount of copper pipe, wieldiness and performance. I daft though, could the loop be bigger to the point where the inductance is tuned by self capacitance alone? A nightmare to build and operate so probably not at all practical, as still larger bore pipe would be needed to get to the higher Q needed for more circulating current and therefore gain. Another show stopper I think is that the maximum length of pipe in the loop you can go to is 1/2 a wavelength, beyond this the current in the loop starts to reverse , with a corresponding fall in antenna gain.
Mike - you have probably exceeded the current capability of the little blue capacitor, it needs to be rated for voltage and current. The doorstop type cap will do the job, as well as the one you made.
Well, Mike. I learned something today. rather surprising for me hihi. making the capacitor exceptionally interesting. would love to come to see this loop in action. 2E0HXU
Very interesting. I was thinking of getting a Ciro Mazzoni but this looks like ot could be one hell of sight cheaper! WIll watch with interest whilst I keep my ears open for news of a capable, co-operative plumber!
Don't Buy..... Build.
You don't need a plumber. Just buy a cheap gas torch, a simple pipe cutter, flux, solder and wire wool...... then you can make some for your friends. Buying is Boring.
very nice I have never used a tx loop but that really worked well. RG 213 has a50 PF / foot I ahve used RG 213 to tune a end fed long wire using high power it really worked on the one band it was tuned for. (10 MHZ) what a good video.. thanks
thanks
Great videos. Would be nice to see WSPR comparisons with other antenna over week say.
Might do that.. 👍
Nice loop. I suggest cleaning the copper and getting some spar varnish and car wax on to prevent corrosion. I'm also concerned about that threaded rod in the weather but other than boxing it off and throwing desiccant at it there isn't that much to be done. It might be fun to have a similar antenna on my narrowboat. Thanks for the great videos.
I will be cleaning the copper, but it is going to be a loft antenna or sunny days only
Que maravilla de antena..felisitaciones
Gracias
🇧🇷😀👍🏻Amazing experiêncie, good work /73
nice job....
Thank you! Cheers!
Nice job yet again Mike... Having trouble finding 22mm pipe here, plenty of 25mm around........... The cost of copper tubing here is horrendous though 😢
It isn’t cheap here 😂😂, cheers Roly.
great video thank you
Glad you enjoyed it
Nice!
Thanks!
very interested in the progress , wanting to build for a 160-80m band, liking the minimal components ( hard to get off the shelf capacitor to make a mag loop, so your trombone cap is really intriguing, hope you publish a PDF plans
Mind_Molester Liaw have a look at the website in the description below.. 👍👍😊
This turned out awesome Mike! Have you done anything else with it?
Seems like its working in the 20 and 40 meter bands and you were wanting to get it into the 10 meter band and do some more with the motor controller.
Its amazing what little space it takes up for 40 meters and looks fantastic.
Nice completion on this and a convincing test QSO I admire your ingenuity and perseverance. KE5TJ.
Thank you very much!
Nice! What capacitance max is the trombone? And when do we get the video of how to replace a length of kitchen worktop before the missus gets home?
178pf, I think??? Worktop replacement..LOL
Great project, thank you Mike. Well constructed loop. Great choice for the motor to drive these caps in the future. I think something like 30:1 RPM gear ratio would be sensible; although I would probably stick to a standard PID analogue servo motor controller (1 IC - four integrated differential amps) - you would need to add a geared position feedback potentiometer (10 turns for accuracy with 3:1 ratio) - but I am digressing here.
With the linear screw driven control all you need is to monitor the MIN and MAX ends of the travel with possible additional microswitches to zoom to the band of operation in almost no time.
At the additional expense I would probably replace the two original capacitors you have made with two adjustable vacuum caps that will cover all the capacitance you may need (they require 30 rotations to change from min to max capacity). That approach would require you to drop the screw and use the driving motor gear on the straight shaft to drive a cog on the chain belt - driving the two cogs connected to one cap each (+ the tensioning roller).
If you do not have the head ache by now - I confess to having one after reading the G3LHZ reference article. It just showed me how little I do know about these magnetic loops :)
73, take care
Regards,
Jansb
Great post Jansb, I have been thinking about a simple microswitch each end system.. :)
@@mike-M0MSN Keep it simple is probably the most sure approach, I agree.
It would require only a simple circuit if you have enough space to install the Min-Max microswitches.
You may run into a problem trying to making capacitor changes for higher bands. Your tuned trombone caps are almost at the max of their dimensional capacity. You can shorten them to give you more accurate tuning on higher bands but the additional capacitor would require some rethinking.
The voltage at the top of the loop is at its highest point of the loop at tends to be increasing as the frequency goes up on higher bands.
Electrically, the trombone capacitor are really two capacitors of the same capacitance connected in series and do share 1/2 of the HF voltage.
On the other hand, the additional capacitor is using the same insulation (PVC). That insulation is under double the strain - full RF voltage (not the half) because it is connected directly to the loop in parallel with the trombone, this is where you can expect flashes overs in the PVC pipe.
To maintain the same voltage strain you may need two of these additional capacitors being in parallel with trombone cap but in series with each other, like another trombone (but with the set and forget tuning). This also opens a field of experiment adjustments on the 2nd trombone caps before it is clamped for good.
73's Mike
jansb
@@mike-M0MSN Reply#2 to the first in this chain..
Coming down from the top of the loop, if you were to first, employ T-type CU joints perpendicular, one to your variable trombone (C1+C2) in series, to the 2nd part of the other (C3+C4 trombone, also in series but adjustable but then fixed) in paraller) to the C1-C2 trombone but on other side of the wooden plank you made to support the loop to start with.
The consideration would heve to be made to the upper side of the plank because of the high RF voltage. I see a top extension here made of some cutting board plastic 12mm Polypropylene cutting board cut to size required by you ( see the www.ebay.com.au/itm/Chef-Inox-White-Polypropylene-Cutting-Board-250x400x12mm/392929288766?epid= 1839336777&hash=item5b7c69223e:g:VwEAAOSwJ5VfUOCI&frcectupt=true
) as an extension to mount the loop to the top of the combined plank.
This can be done at the top and at the bottom of your wood plank support. The Polypropylene RF electrical properties beat the wood in all respect and are cheap and you can cut it any way you want.
I may not have much more to add - except, the additional FIXED trombone cap can be made with ONE high quality cut to size Coax instead of the two copper tube capacitors (C3+C4).
Cheers,
jansb
Mike you do some great stuff on here, and invaluable to new ham hopefuls and whoever else. keep it up mate. I'm on with one myself with a stepper motor, and home made variable capacitor, but can't get low enough capacitance on 20. so, might try a trombone as I could unscrew it out to 0 capacitance? Owen G0RCL
If you have too much capacitance, you can reduce the diameter of the loop just a little. Thanks 👍
Excellent job and video Mike! 73 KJ6IHZ ✌
Mike, cool solution to the added capacitor, but your 2:1 bandwidth on 40m suggests losses somewhere. My guess would be the dialectic in the caps. PVC and CPVC are pretty lossy, especially at RF voltages typical at the hi-Z end of a mag loop. Take a tip from the way heliax or 9913 are made - I'd try making the dialectric in the caps mostly air, using a couple small rings of HDPE tubing, or even a spiral of teflon tape on the inner tube, to keep it centered.
Having to tune more often after QSY will be a downside, but the efficiency may improve markedly. Can't argue with results though - if they can hear you, mission accomplished! 73 - AE4KR
Yes mixture of the PVC dielectric and the co-ax.... Thanks 👍
Gee I would have been happy with the SWR at 1:3, but not sure how it would have been through the rest of the band. Great video. Fun build. 73 Clark KG7LOI
👍
Nice finish execptional job fantastic 73 form kb2uew
Amazing! Done with such ease and accuracy and to have it "working" on 40 & 20M bands! Smart capacitance solution!👏 Both of them!👏 SUCCESS!
Do another loop for 10, 12,
15, 17M bands.
73s de Gunnar sm6oer.😊
Maybe another day, thanks you Carl
Great MIke,
a beautiful channel yours, just registered ...
I build loops much less professionally than yours ... I usually use scraps of things found on the street or at fairs for Ham ...
a perfect and very tidy construction ... I see you have an equipped laboratory at your disposal ...
I wish you all the best.
Regard from Italy.
73. Giuseppe iz0gzw qrp.
Welcome aboard!
Hello Mike. I used a gamma match myself, I found it easier to get a 50 ohm match. I also had the same issues getting enough capacitance with the air variable capacitor I was using - I have just replaced it with a 5 to 250 pF Russian vacuum cap and now I can tune 60 through 15m. Keep up the nice project videos. 73 de ZS2VR Vaughan
Cheers Vaughan, I think the next mod is the Gamma Match.. :)
@@mike-M0MSN I also cobbled together some very basic code for Arduino, 4 buttons driving a stepper for tuning. If you want send me a mail, details on qrz.com
60 thru 15m is quite an impressive range. I was curious to know what your loop diameter is please? Also, approximate dimensions and tapping point for the gamma match. I built a mag loop with a small inner loop but fancied having a go at a gamma match type.
@@Steve-GM0HUU Hi Steve. My email is on qrz.com. Drop me an email.
I have watched all your loop videos and this one just FASCINATES the heck out of me. We all learned how capacitors worked when we took our General or (insert brittish name here) , but to see it in action built by a non engineer is just inspiring. I love the AV-680 , but my next antenna will be this one. great work M0MSN from kn6jvs 73 . feel like a kid again at 63 is a great thing. do have one question what is that coax you use on some of your videos , that looks like the SHIELD is solid copper ???
Hi, Thanks for the nice comments, the coax used on this video was RG213, :)
Bravo.
👍 thank you
Hi Mike, you have very much peaked my interest in antenna building with this project, I have already started getting the parts together. Do you have any plans to publish a quick reference to the lengths of pipe etc? My intention is to build it using 135degree couplers instead of trying to bend the pipe. Great series, looking forward to the next
Cheers Mark. :)
Well done Mike. Fantastic video you have got me very interested in building one now lol de Tommy vk2ir
👍👍
Cool i'm like it from indonesia
You might check out KB9RLW's channel. He did some videos of the mag loops and remoted them and used a motor to adjust them and used a field strength meter at the mag loop to determine when the antenna was at its resonance. It worked well. Just another way to skin a cat so to speak. I have been enjoying watching your videos on building antennas.
Hello Mike, my congratulations for this outstanding realization. Great idea the trombone, great construction skills of you. That’s real ham spirit.
One off topic question. I don’t know well the knwd 890 but I see when you talk a bar that to me seems the alc bar goes all the way full scale, well beyond the normal alc zone. Is that normal? Is it correct what I’m seeing?
Thank you and 73
Diego
Many thanks for your comments, The Kenwood seems to run with ALC at a very active state regardless of the settings???
Nicely done Mike. But you didn't mention how you arrived at the length of the copper pipe you needed for the 100pf capacitor.
Great work.
Pure guesswork, I would have been happy with any value over 80pf and under 150pf and would have cut down or made a new one.. 👍
شكرا
مرحبا بك
The trombone might benefit from increasing the effective diameter of the moving 15 mm pipes. This would increase the maximum capacitance and provide greater mechanical stability.
This can be done by threading multiple "staight couplers" onto the 15 mm moving pipes. There is an internal ridge in the middle of every straight coupler to stop this happening. But that can be defeated. Better than drilling them out, straight couplers can be *forced* onto the 15 mm pipes.
This can be shown by using a simple G-clamp. But that would be good only for ONE straight coupler. A special jig would be required to complete the operation. That might require a specialised version of a G-clamp, a challenge to ingenuity.
I've seen couplings that they call "repair couplings" which omit the center ridge entirely. They're designed to slide over the outside of a pipe easily to aid in the repair of pipes already fixed in place inside a wall.
Those little blue caps heat up and change value.
yep they do.... lol
I tried using some cheap blue high voltage ceramics from China to add extra capacitance to a mag loop. Didn't work for me either! Ended up using some old silver micas I had in the junk box (put them in series to up the voltage they could handle).
First of all good vid kept my attention through out both and loved the novel ideas you used. certainly be having a go at this for sure as last projects with a Quagi 2m 9 el with conductive boom and 16El 70cms Quagi beam. The loaded coil mini moxon 20m needs more work with a remote at antenna tuning system as losses occurring effecting its back and forth gains. Better effective tuning. Now this brings me to a question how big would a 80m one be and can you do the add on to turn it into an 80m. Or could you add a cap to other side of the trumpet doubling up on the add on. Thanks again for a inspiring Vids Karl 2E0FEK Kernow
Still waiting to see how you are going to remotely tune it and adjust the trombone. 10 Meters would be good to see it working on. I have not done much with Loops so I am just interested to see how it all works out.
We shall see, not sure about 10M will have to try.. :)
A lSmall Transmitting Loop has a finite tuning range. Three bands are about as many as are reasonable to go for. Use some free modelling software. There's plenty around. Good luck.
This is a great project. Going to have to figure out comparable sizes of tubing. I doubt I will luck out with imperial sizes. Are you going to use a stepper motor?
3/4inch. Have fun!
Absolument super. Félicitations F4IWJ
Nice work...👍 Wish I had the Smarts (And Tools) to make one -- Just for Shortwave (RX only) 30 KHz to 30 MHz.. If possible, with that Bandwidth. What dimensions it would be.
Thumbs up! Subscribed! Awesome channel my friend. Thank you.
Many thanks
Well done Mike, would you be able to compare to your other antennas?
Maybe in the future