HAM RADIO: Building a Coaxial Magnetic Loop Antenna. COAX MAGLOOP: Double Loop:

[@MikeDent]

Nice job. However i’d have been hung drawn and quartered had I attempted that in the kitchen. I have some Andrew’s Ldf4-50 in the garage. Can only cry the amount of those capacitors i threw away many years ago 😢

[@AbdulMalik-in3cl]

Good job, Mike. . . .I have made it with 5/8 heliax cable

[@jamesfoley2720]

I have a few meters of some 7/8 in Andrews in the rafter of my garage. I may try this as well. Thanks for the inspiration.

[@mike-M0MSN]

Have fun!

[@michelfrias7193]

Are you soldering with silver or tin-lead? 6:36 Tin-lead is bad idea when you will TX with more than 10w

[@Keith_WB2VUO]

Mike: I built a 2-turn magnetic loop from CATV RG-11 here. My cap for 10 watts is a dual receiver 365/365 pf cap with the sections series connected. The loop covers 80/60/40 meters and is rectangular to fit in the family car for portable outings. It's102cm x 90 cm and the loop conductors are separated by 7 cm center to center. A fun project loosely based on your KZbin videos! Lots of fun, and looking forward to some air time... de WB2VUO

[@mike-M0MSN]

sounds good, have fun. :)

[@gilbreathca]

You Sir are the David Attenborough of ham radio! ha! Love the videos - keep up the good work homebrewing antennas!

[@mike-M0MSN]

Great praise indeed. Thank you 😊

[@dxscotland5901]

Great job mike,I used micro boar copper for my loop and you are right the variable caps are bloody expensive now

[@mike-M0MSN]

Yes they are

[@joohop]

Nice Work Bless Up Fella

[@jean-emileelectrobricoleur1144]

très bien et un travaille très propre merci pour tous 73 q r o

[@tangobayus]

I have an MFJ tuner. I wonder about using a ready-made piece of coax with an SO239 T and connecting it to my tuner. Maybe 10 feet of coax?

[@mike-M0MSN]

Not sure if that will work, give it a go !

[@ianxfs]

Another nice loop Mike. Very informative on build methods 👍🏻 Maybe nylon chopping board spacers for those without printers.

[@mike-M0MSN]

Good shout Ian, or plumbing pipe

[@sootydave1]

Mike. I have to ask. Why do they use coax for the main loop? Would small-bore copper tubing or 4 gauge power cable do the same?

[@centralna.poczta4648]

Hello ... Interesting design of the antenna ... I have a question ... What type of coaxial cable is used on the main loop. What is the capacity of the variable capacitor. I do not understand English very well. Witam... Ciekawa konstrukcja anteny... Mam pytanie... Jaki typ, rodzaj kabela koncentrycznego jest zastosowany do wykonania głównej pętli. Jaka jest pojemność zmiennego kondensatora. Nie rozumiem zbyt dobrze angielskiego. Pozdrawiam

[@mike-M0MSN]

kabel koncentryczny to heliax (hardline lub Andrews), a kondensator ma od 9 do 300 pf the coax is heliax (hardline or Andrews) and the capacitor is 9 to 300pf

[@centralna.poczta4648]

@@mike-M0MSN Dziękuje..

[@centralna.poczta4648]

Ciekawa, interesująca seria filmów. Pozdrowienia z Polski

[@mike-M0MSN]

Wielkie dzięki

[@edgarmontalvodelgado5713]

Saludos y felicitaciones, me podrías indicar cuantos metros de cable usaste para formar las dos circunferencias y en que frecuencia resuena mejor. Un abrazo desde Lima, Muchas Gracias ,

[@pd9rd]

Another great and very interesting video Mike, Thank You! 73

[@mike-M0MSN]

Many thanks!

[@J1mbo888]

Great work Mr Mike.

[@mike-M0MSN]

Cheers James

[@cacciskagrana6603]

so that the 2 terminals of the loop are not connected, but prepared for the variable capacitor ?.

[@boxingday11]

Thanks Mike 👍🇬🇧❤️

[@mike-M0MSN]

👍

[@bernard83110]

i don't undestand some mesures , if the coupling loop 32 Cm diametre= 100Cm , it's a half wave ? so it's (32 * π) /2 and main loop is 94 *2π (lenght of coax ) .

[@ERICtheLATE]

Besides the flexibility, wx proof coating, and just cool factor, does using coax for the big loop add any other benefits? Does the center conductor help it be more wide banded? There is a fridge on the curb, and the copper is still there, would like to mimic this, but no broadcast or cell tower scrap around here.

[@mike-M0MSN]

No, you can use any thing for the coil, copper pipe is the best thing I have found..

[@kellypaws]

Top work.

[@mike-M0MSN]

🤙

[@chiphungerford]

Mike, great looking antenna did you have a plan you were working from laying out the loop sizes and wiring layout. I am thinking of creating one to try in the attic. I would want to set one up for 80m-10m and maybe another for 2m & 70cm running barefoot out of a Yaesu Ft 991a (100w or less) I would be looking to do remote tuning as it would be in the attic and the shack is in the basement

[@KU8RLY]

You said without a cap it was resonant at 15mhz. How did jt receive on other bands?

[@Pascal-F11DRE]

Bravo tres belle réalisation 73's

[@pa6552]

Hi, is the location of the capacitor critical? Ie, any option/possibility to have it further away from the antenna?

[@mike-M0MSN]

You can put the cap anywhere as long as it makes a LC circuit.

[@pa6552]

@@mike-M0MSN Thanks! wrt the diameter of the large loop - any benefit ( or rather, what would the effect be) if I made it larger? 3 loops instead of 2? What about 4 loops that for a "ball" - ie, N, S, E and W orientated?

[@philippejoigny5928]

Very well Mike, at next time on the air (F1PBT)

[@CarlosAvellanet]

Love your videos and they've inspired me to make my own. I noticed the loops spacing get tighter at the bottom, I don't think the 10cm spacing is kept. Was that on purpose or what is the reason? I made my mag loop using PVC pipe step by step by your instructions and I can get it to tune on 40/80 but haven't been able to tune to the 20 meter band. I am using a 20/250pf variable.

[@Scif64]

Nice one Mike... I have been looking for something to be used in my apartment and mag loops seems like the only solution... nice bit of work there and looking forward to an update. 73's

[@mike-M0MSN]

Go for it.. :)

[@kimsan1803]

Mike how did you make a dia mtr at 32 cm when you write the coupling loop is 51 cm 🤔

[@mike-M0MSN]

??

[@kimsan1803]

@@mike-M0MSN Look at the video 6 min in you write " couplingloop this one is 51 cm and dia at 32 cm " then i ask how did you do that and what is the site of the couplingloop ;-) or is the dia not 32 cm...

[@mike-M0MSN]

@@kimsan1803 Oops, should have read 91cm in length around 32 cm dia.. Sorry but thank you for the correction.

[@kimsan1803]

@@mike-M0MSN Thanks then I will try again 😉 and make a new one lol 👍😜

[@2EOGIY]

5:00 soldering core with the shield together on both ends will give you less resistance. Have you tried to use flux? Try to find "no clean" one. Works better than resin cores inside the solder.

[@mike-M0MSN]

Thanks for the tip

[@ekimlebenk4183]

What about the skin effect? As far as I understand, the core will not help in reducing the resistance as at higher frequencies the electrons are pushed to the surface of the conductor

[@2EOGIY]

@@ekimlebenk4183 that's the wrong understanding of skin effect. imagine a round bar and flat bar, both with the same cross-cut surface. the round bar has a smaller surface and the flat bar could be theoretically thinned out to have an external surface up to infinity, but both will have the same resistance as the cross surface matters not the skin surface. Skin effect just tells that electron likes to be outside, but if they can not be there then they won't and you have deeper penetration. Good practice 4A per 1 mm^2 safe practice 2A per 1mm^2 but that's irrelevant from the resistance part of the impedance. If you would have to take into consideration skin effect that means your magnetic look is improperly built. (diameter to length ratio). it also means you are one of the reachest people in the world to have such an antenna for HAM HF bands as it would take humongous tons of copper.

[@littlebear5219]

That’s big $ coax amazing !!

[@mike-M0MSN]

Thanks!

[@intruder1951]

Hello Mike, I did Bild the large loop. That one does his work great. But, now I want to bild this one, but before I cut the Andrew wire, what frequency's work this small loop. Grtz Gerrit.

[@mike-M0MSN]

20 to 40 Metres I believe, I no longer have this loop so I cannot check.

[@ben2e0omr]

Mike, you make it look so simple. I just might try this one.

[@mike-M0MSN]

Thanks Ben.. :)

[@N3OST]

may I please have the SLT for the printed spacers?

[@BillBerzinskas]

awesome build, any plans to share the printed part designs?

[@mike-M0MSN]

Sorry, no. no longer have the files.

[@markg6jvy135]

Nice build and video as always Mike 👍👏👏

[@mike-M0MSN]

Thanks 👍

[@TEGEscalator]

Greetings from Belgium 73 Albert. Vidéo very nice thanks. 👍👍

[@mike-M0MSN]

Thanks👍

[@cyberia55]

Shouldn’t the exciter loop be positioned at the center point of the two loops (the bottom, in this case)?

[@mike-M0MSN]

As long as it works....

[@richardb6376]

Hi Mike. Did you find a variable air capacitor.

[@mrtonicsvls3624]

What kind of capacitor you used? I can't see in this video. Thanks.

[@mike-M0MSN]

see other video's

[@Jah_Rastafari_ORIG]

The colloquial term we use for that type of coax in the US is 'hardline'. Primarily for repeater installations and so forth.

[@mike-M0MSN]

Thanks for the information Jah.. :)

[@markwagner7023]

Can you tell me what kind of coaxial cable you used here? I’d like to take a stab at making one of these antennas. Thanks!

[@johnk8091]

All antenna building takes place in the kitchen 😂

[@mike-M0MSN]

True story

[@PhilG0BVD]

He must have a very understanding wife with the way the solder was dropped all over cooker and worktops!

[@paulshaffer9674]

I made a Magnetic Loop out of 6 feet of RG8. Worked well 15 through 40 meters. KG7IRJ Ohio Extra

[@courierdog1941]

What about a trombone capacitor copper pipe and PVC pipe as the isolator (insulator) using size (Diameter) and length to effect the total and variable capacitance to tune the loop.

[@AlexHitchins]

Be interested to see you make a variable capacitor. I wondered if you could make the plates via designing pcb’s. Dual layer, heavier copper with plenty of vias.

[@mike-M0MSN]

Possibly!

[@bigliftm]

Question : will RG213 coax work as well ? Q2 = solder the connections to the braid ? what to do with the coax core. ? pls some more details as i got plenty of RG213 laying arround. No 3 d printer unfortunatly. 73s from PD0ROH

[@mike-M0MSN]

Good to speak on DMR, Yes you can use RG213

[@bigliftm]

@@mike-M0MSN This channel has super service 😜😜🤣🤣🤣🤣 Q&A on DMR worldwide 91 😜🤣🤣🤣

[@timg5tm941]

Great job! 73

[@mike-M0MSN]

Thanks Tim

[@davydacounsellor]

Brilliant

[@lampshadesneeded]

Why not electrically shielded feed loop?

[@mike-M0MSN]

you could use that...I had Cooper pipe.

[@TomG2NV]

Nice work as usual Mike! I'll be watching this build with particular interest as I've been considering a magloop build myself for some time and that large heliax seems the best stuff by far. I want mine to be able to handle respectable input power, Have you considered using a vacuum capacitor? Expensive but very reliable or an air spaced cap but immersed in oil again capable of greater power handling but also far less susceptible to corrosion for a permanent outdoor install. Keep em coming, Great down to earth proper ham radio vids nicely done! Many thanks. Tom, 73!

[@mike-M0MSN]

Thank you Tom.. 😀

[@mysticwolf2842]

This looks like a useful antenna where can I get the plans for it ?

[@mike-M0MSN]

I have not published any

[@Nathan1975Liggy]

Be interesting to see you show us how to build an 8 band mag loop like the one sold by 2E0ERO. I would love one of his 8 band magloops but the capacitance switch being at the loop is no good and the price is far to high.

[@mike-M0MSN]

I do not see the point, you loose to much efficiency (two bands is the way to go)

[@kellypaws]

Mike, have you go this lovely bit of kit to tune on 80? If so, did it work well? I'm keen to build one, but specifically for 80, since it's an utter pig to fit in an 80 long wire here. Hoping you can find the time to reply!!!!

[@mike-M0MSN]

20 and 40 at the moment.. 👍🏻

[@robertfoster6070]

Ray at the Radio Workshop in Worthing might have a capacitor.

[@mathewgeorge9550]

Complete novice here. Can we make them for 15 - 50 kHz? If yes what dimensions might work? Thank you.

[@mike-M0MSN]

I'm guessing you meant 15 to 50 Mhz or 20 to 6 Metres yes you can ( its a 10th of the wavelength)

[@mathewgeorge9550]

I meant VLF.

[@Stuff_happens]

Fancy. What did u use for plastic spacers? What was your fill %? Just curious. Haven’t used my printer in a while. I use Fusion 360. Great antenna project. Would like to see this antenna with a capacitor. Are you planning on using a vacuum variable?

[@mike-M0MSN]

20% fill, but it took all day printing.. air spaced Cap, due to cost $$$.

[@johnnorth9355]

Great video . I am studying for my Foundation and one of my post licence projects will be to make one of these. I wonder how long before the Chinese start knocking these out in volume and low cost though ?

[@mike-M0MSN]

Not long I think.. :) 😂

[@debojitacharjee]

What is the formula to calculate the main loop and the coupling loop?

[@mike-M0MSN]

www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm#top-of-page

[@rushymoto]

Should not the driving loop be 1/5 of the electrical length of the resonant loop, not the diameter?

[@mike-M0MSN]

Thats a good question, Its standard diameter is 1/5 that of the main loop. However, I have seen designs with 1/3 to 1/8 the diameter of the main loop...??

[@rushymoto]

@@mike-M0MSN I downloaded a document all about considerations of using mag loops and 1/5 is what it said, but as you use multi turns to make compactness surely you should do the same with the drive ring, or maintain the electrical length ratio, as we know, wave length regards electrical length and not the shape it is packaged into.

[@Nathan1975Liggy]

What diference does having the 2 loops make as oposed to just one?

[@mike-M0MSN]

Not a lot just a bit smaller.

[@geraldcampbell6834]

Is there anyway to get the 3D stl files for the printed parts I would like to make one of these antennas!

[@mike-M0MSN]

On Thingsverse

[@gufranozcelik9553]

Wouldn't the small loop diameter be 1/5 of the large loop diameter?

[@mike-M0MSN]

Try it out!

[@jeffreycohen3451]

Forgive my ignorance, but why can you NOT transmit on the Coax Magloop?

[@mike-M0MSN]

Simple Jeff, it was resident on 15MHz and not 14MHz so the SWR was over 25:1....

[@johnanthonycolley3803]

For attaching a terminal to the outer of the coax, Could do with a more powerful soldering iron .. de John G4XJC

[@mike-M0MSN]

Thanks Jon One on order. :)

[@ukm6yik69]

Have you got the stl files. And would 213 fit the holes OK do you think. I would love to build one and have a 3d printer and some 213 lying around.

[@mike-M0MSN]

watch this space...

[@cliveharding1825]

Dou you have the stl files handy or the dimensions so I can create them?

[@mike-M0MSN]

sorry no, you will have to create them :(

[@warrenphillips69]

Is that LMR600?

[@mike-M0MSN]

No it's Andrews Helix

[@George10767]

While I applaud all efforts to learn by experimentation, my "gut feeling" is that any multi-turn magnetic loop antenna is likely to be retrograde by comparison with the conventional single-turn. It appears that the single-turn loop is *more* than just an inductor. In effect it is a centre-fed half-wave dipole where the ends of the dipole have been pulled round to form a circle. And the ends of this "half-wave dipole" are connected together with a variable capacitor. So the entire loop radiates into free space. There is high voltage (across the variable capacitor), and a high current (near the feed point). It may not look like a half-wave dipole, but it works very much the same way. (However, unlike a half-wave dipole the circumference of the loop is *not* determined or constrained by the transmitted wavelength). The important consideration is that there is a *voltage standing wave* around the loop, where maximum voltage is across the variable capacitor. But this "pure" arrangement is severely upset if the loop is multi-turn.

[@mike-M0MSN]

I would agree, a single loop at the correct size for the band/s you are trying to cover will work far better than the smaller twin, just like a 160M halfwave (80M) antenna will work far better than a 40m coil loaded shortened antenna on 160m, but hay!!! small garden small loop...

[@W4TRI_Ronny]

Do you have a link to get the STL files? I have some Hardline jumpers here that size. Great stuff! Thanks! 73 K4RJJ

[@mike-M0MSN]

No, sorry

[@petervomfischland3568]

Hi Mike, well done! It‘s another great video and it looks so simple! vy 73 de DK7- -

[@mike-M0MSN]

Many thanks!

[@MeineVideokasetten]

Hey dr op. Is it usable for 80m to 10m band?

[@mike-M0MSN]

Hopefully will try once a get a cap... 😀

[@MeineVideokasetten]

@@mike-M0MSN Thank you. Mike.

[@leos9865]

Is a double loop better than only one loop?.

[@mike-M0MSN]

No but smaller..👍

[@MrDwadi84]

What type of coax is it?

[@mike-M0MSN]

Andrew helix

[@cacciskagrana6603]

i dont understand how does it get so low swr without variable capacitor.

[@mike-M0MSN]

The length of the loop is a perfect match for 15.4 MHz as it acts like a fixed length magloop until you close the loop with a variable capacitor, as this adds variable length electrically and because the length changes so the frequencies move.

[@paulhastings3109]

I only need a three D printer Lol. 73 KQ4CD Paul

[@jamesfoley2720]

Are you single or very brave, soldering over that nice kitchen counter top??? 😎😇

[@mike-M0MSN]

brave...

[@peternilan4276]

wow that looks like real heavy duty coax nice work mike looking forward to see how it tunes with a capacitor. pete G0LVG

[@fletcherreder6091]

That's LDF5 with a nominal power rating of 14kW and an attenuation of 0.64 dB per hundred meters. What's crazy is that the line goes all the way up to LDF12 which is 2.25 inches in diameter, has a rating of nearly 40kW, and an attenuation of 0.3 dB per hundred meters. If only the connectors didn't cost hundreds of dollars. 73, KD2TDE

[@peternilan4276]

@@fletcherreder6091wow that's great coax i wonder what the cost is per meter ?

[@fletcherreder6091]

​@@peternilan4276 Glad you asked, since it looks like they replaced the LDF series with the AVA series when I wasn't looking. Here's a distributor with a datasheet: www.talleycom.com/viewProduct?rlProdNum=ANDAVA5-50 Below 1dB/100m loss over the entirety of HF! Also the connectors are not as expensive for the 7/8" stuff as they are for the bigger stuff that I'm used to; only ~$40 as opposed to >$300.

[@georgessamara5592]

I can get a similar cable. All I need now is a transceiver and 3D printer :-)

[@9PAT508]

Yes....i'm the 450 thumbs up heheheh nice video and very informative..thanks and keep them rolling love the magnet loop for SWL.....have a good life

[@mike-M0MSN]

Thanks 👍

[@DonnyHooterHoot]

LOL! My cheapo MLA30+ can pull in more!

[@andyshaw2800]

You should have used a little bit of washing up liquid to get the spacers on

[@mike-M0MSN]

great tip

[@acestudioscouk-Ace-G0ACE]

Really interesting and well made video as always. At some point it would be good to hear the pros and cons of trombone, air variable and vacuum capacitors in your practical experience.

[@mike-M0MSN]

Noted!

[@andylinton2798]

Search on Ebay for 'Eddystone' - you'll find airspace caps there.

[@mike-M0MSN]

Thanks Andy

[@daveschwarz5279]

Have you tried to couple the larger loop with a toroid, FT 240-43 or FT140-43 a simple 1:1 would give you a really low SWR.... some people use an ATU on their radio to help out with the matching. A toroidal match or a gamma match really work better than a small coax loop.

[@mike-M0MSN]

Thanks Dave will give that a try.

[@AmRadPodcast]

I use an FT240-43 on a 5.8m circumference loop for 40m and I can get very close to 1:1. Unfortunately you have to change the number of turns on the toroid to achieve decent SWR on a different band. Eventually will try using a remote relay to "adjust" the number of turns

[@Tump2010]

when you transmit I would love to see a ft8 pskreport of it and your copper tube version

[@mike-M0MSN]

Will do someday

[@thedancingalien7766]

Us aliens like soldering

[@mike-M0MSN]

cool or should I say hot...

[@chrisbartlett6022]

Mike, i have a couple of Air spaced capacitors you are welcome to look at / borrow.

[@mike-M0MSN]

Thanks Chris..👍

[@Justin-bd2dg]

Hard line?

[@mike-M0MSN]

yep 😁

[@GreyGhost-r4z]

Can you share the 3D spacer file ?

[@mike-M0MSN]

Maybe later

[@genesky61]

So why No set diameter for the magnetic loop antenna. I find it frustrating to communicate with Ham radio Humans. I am aware that the modulated electric field works best at resonance with element length. So what about the magnetic field?? Please provide a straight answer.

[@mike-M0MSN]

I will try and possibly fail, however here goes... The loop Magloop antenna or Small Transmission Loop (STL) is basically an LC-circuit that has to be tuned to resonance on the desired operating frequency. It is normally 10% or 1/10th of the wave length you wish to operate on for example circumference of just less than 8 mtrs for the 80m band. The loop by itself is an inductor that has the shape of a closed-loop. The coupling loop is is around 1/5 or 20% of the larger loop and acts as the pick up. The wavelength of the large loop is tuned using a variable capacitor (it fools the smaller loop into thinking the outer loop is bigger than it is) and therefore changes the resonant frequencies. For more information check out www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm#

[@genesky61]

Ok , you did good. Simple to the point. Have another question. Why is the magnetic field wave length 10% of the electric field wave length?? And I am interested in magnetic loop for reception of the VHF Tv Low band channels 2 thru 6. Magnetic field reception has a lot less interference then electric field reception on Tv channel 2 thru 6. And yes I know that magnetic loops are less efficient at frequencies above 30 Mhz , But that does not mean that it wont work. And there are magnetic loops for the FM radio band and that is above Tv channels 2 thru 6. When I have brought this issue up in the past , Ham Radio Humans , Switch OFF and refuse to talk or think about it.

[@kellypaws]

No antenna is complete without some cable ties! Mine are made entirely out wire and (mainly) cable ties.

[@mike-M0MSN]

too right....

[@BoB4jjjjs]

I can't afford a 3D printer :-( Have to chop up the white plastic chopping board and spend the next few nights sleeping in the shed! :-((

[@mike-M0MSN]

I have made one using 50mm and 38mm plumbimg pipe that works well, (next video).. :)

[@BoB4jjjjs]

@@mike-M0MSN Ah yes, I could use the plastic plumbing clips to hold it all together. 10mm Microbore pipe should be easy to bend into a circle. EDIT: Look forward to next video.

[@kellypaws]

I'm not sure how these kitchen activities aren't met with repercussions....

[@mike-M0MSN]

Oh they are!!!

[@talkintech9363]

why wont you share your 3d print files so others can build this project???

[@jonfortier3664]

if two loops are better than one then why not 3 or 4 loops ???

[@123Lesgeorg]

Hi Mike, I have some LDF2-50

[@mike-M0MSN]

make a loop

[@123Lesgeorg]

@@mike-M0MSN do you want it, 2 x 25m 1 x about 10m and a LDF-2 SMa connector FOC or it will go in a skip

[@mike-M0MSN]

@@123Lesgeorg Yes would love it.. Drop me a note via QRZ

[@123Lesgeorg]

@@mike-M0MSN I sent Callum an email as I could find his email easy, he said he forwarded my email to you as I said did he want it if not ask you. [e-mail] will find me

[@eventail2001]

I think you would have been better making a mechanical joint with the wires you soldered on for the capacitors, then soldered them. Relying on just the solder strength could lead to a future failure

[@mike-M0MSN]

Agreed, I have now removed and done just that..

[@wawolff6085]

Why doesn't anyone show a loop fed with a gamma match?

[@mike-M0MSN]

Good point.