Ham Radio - Building a spiral loop antenna for 20 meters
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- čas přidán 11. 07. 2024
- NOTE: SM0VPO is not Richard. He’s Harry Lythall. My apologies to Harry.
I've wanted to try out a spiral loop for awhile. I loosely followed Frank, N4SPP's notes on his page linked below. Pretty easy to throw together, broader bandwidth than a traditional magnetic loop.
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Hit me up on the echolink repeater down by my house: W9TE (Node: 519521) - Věda a technologie
One of the first radios I took apart as a boy was a 1945-50 valve (tube) radio made by the Bush company, it had a spiral loop antenna wound on the back panel.
Good job Kevin! I too have wondered about how well the little magnetic loop antennas work. Very surprising to see you were heard so far away. It is tempting to scale it up to see what performance may be had on 160 meters. 73 and thank you. DE K7RMJ Frank
Great antenna project there Kevin. (Subbed) I'm currently a SWL studying for my first UK (Foundation) license and I live in a house with a very small garden to the rear. This design is going to help me overcome a lot of the issues I face with HF propagation, particularly on the longer bands. all the best and good luck with the job hunting.
This was useful to watch, thank-you. It's amazing what can be done with small antenna systems.
I love it, a Kenwood TS-430S in the shack. I've had my since 1983 and I have worked the world and I am still working the world!
I think that this is one of my favorite videos. I've probably watched it 10 times for more.
I am trying to improve a WWV receiver on 15Mhz. This looks like an easy antenna to make to experiment. Thanks to you for exposing this design, and to Frank and Harry.
That's really cool. I have visited that page many times and have yet to experiment with it. Best of luck finding gainful employment. If it didn't cost so much to ship them I have an old 101 that I picked up in a hock shop for a few pennies and FL-2100B that was chewed up by the mice. Not a wire left anywhere inside of it.
I have only had my ticket for about 1 year now and made General about 3 months back. Although I have learned a lot from the Amateur Logic YT and Ham College YT channels, I ran across your's searching for information, and have I every enjoyed it. You teach stuff from the practical level that makes sense rather than theoretical.
Kevin, I know your back pain. I drove big trucks over-the-road for about 2 Million Miles, and was forced to retire early due to a neck injury that required surgery. Once that was completed, my body was able to tell me what else was hurting. Arthritis in the knees and hips, lower back pain constantly, and inability to sleep more than 4 hours at a time. If it weren't for my three Terriers that I have to take walking about every 2 hours on leashes for about 1 mile, I would have frozen up by now. We don't have much hill here in Bayou Country in Louisiana, but the walks do good.
73
Moe K2JDM
Thanks Moe. That's exactly my goal, keep things simple and just pass on what I've figured out in an accessible fashion. You got it on the walks. If I didn't do that daily, I'd be stiff as a tree by now. Thanks for watching!
Yup, the antenna info and the DuinoVOX have been truly helpful. i made an old-style (WW2 surplus) homebrew 80 meter receiver back in the early 1970's but never could pass the CW testing. So I just listened. Thanks again.
Oh, did you build yourself a duinovox? I'd love to see pics of your build if so! My email is good on QRZ.com.
Waiting on parts to build it.
"Neutral Spine"
Very good. You made it so simple and clear, I got an idea for an spiral loop antenna to use with my MFJ-936B loop tuner. I wanted to do an 80m loop antenna, but it would took a lot of space if I follow the MFJ-936B table on its manual service. Thanks!
Watched your video tonight, seeing I am busy making a fan mag-loop myself. I went out and bought some lengths of dowel (1 1/4" dia. Up-right mast, and 1/2" dia. for the cross piece. I made a 1/2" hole through the 1 1/4 at the 2 ft. mark, and stuck the dowel trough the up-right mast section, so I had a cross frame. Each piece is 2 ft. from the center of of the cross, where the wire will be strung up on. The out-side span of wire, will extend 33" between each leg of the frame, and each turn from that point on will be 1 inch apart, till I get 8 turns, before it's connected to a variable cap. From there, I'll add in the pick-up loop, using the upper 3 legs of the frame for support. What I like about it is, all the holes made for the wire to be strung through are perfectly in-line with each other. With this sized frame, I can also add more length of wire if I wish to do so, on the frame, down the road. The full length of the horz, leg from one end to the other, is 4 ft long, while the Dowel used for the up-right is 6 ft. long (having extra length for mounting abilities below where the strung wire passes through the frame at the bottom). I have a screw type, Christmas Tree stand, I can use as a stand base for the antenna. I have to get a wee bit more wire length, to finish the project tomorrow, and expect it to work quite well once in service (Sadly, I didn't buy enough length of wire, as I built the whole thing larger than I first planned on building it). Dowel and wire cost me around $75 overall. I'll be using it with my computer's SDR programming for receive only at the moment, but should be able to transmit with it if needed, with a fair amount of out-put power, with the size of wide gap, Variable cap I have for it. I'll will mount the cap. on it tomorrow (once I finish the wiring). Should work at 15 to 20 watts. transmit, quite easily (possibly higher, find that out a wee bit later). I also have a large copper pipe Mag-loop being made, which also needs to be finished up this week, with a coupling hoop. I have quite a large cap. coming to install on it. It that should be able to handle, 100 watts with no trouble at all. Copper Mag-Loop is mounted on a PCP pipe frame, with an old, very wide, worn out electric fan base for a stand. Anyways, having fun making both of them, and even more using them on top of a high hill not far from where I live this summer, that's part of a city park. 73 for now. va3grp
Awesome Kevin, you could probably put a fixed capacitor in parallel to the variable to increase range and probably tune down to 40m or even 80m. Great video as always. Best 73 from N2SAL
Nice video and great to compare to a bigger loop !
hi Kevin i've seen a lot of your videos and you do it so cool
Hi just found your channel intresting to see someone doing Home brew stuff instead of buying every thing I used to do alot in the 1980 but lost interest in ham radio when every one just purchased kit I am still licensed G1RBZ Here in uk you got me intrested again so have Subscribed Cheers Geoff.
Very nice. Thank you for sharing.
I'm thinking, if you wound inside to outside, it wouldn't be so hard to pass the "loom" back and forth.
Your referral to a "regular magnetic loop," kept throwing me for a loop. Because when I was young a spiral loop *was* a 'regular' magnetic loop.
Wow. Never thought to use an SDR that way. I was about to ask how you were generating signal to the antenna.
Good job Kevin73!
pretty cool, i may have to try one for 80m and use just for receive. we do 3 state nets (MN,SD,ND) one after another and some stations don't come in well on my EFHW. if it has better ears then the endfed that would be great.
Kevin, would using 14ga stranded wire change the spacing between loops? If so, would you know by how much (or how I would calculate that?) Thanks!
Bought a spiral loop antenna five years ago in a double loop directional yagi configuration. Was never happy with it and seemed to show all the same issues you documented in your SDR test. Still find a well made magnetic loop for below 40m is the smallest functional space you can use inside an apartment. - N1KTJ
What does this have to do with glazed spiral ham? This is what came up when I punched it. Also can you recommend a good honey glaze or small matched antenna tuner so I don't have to use a balun?
Very cool. Is your variable capacitor from an RC car?
Often wondered how good these were. It looks like a simple construction for a good RX antenna. I wonder how big it could go for it to be on the top part of the bands.
Nice video and the making of a more better one would interest me. Making it out of PVC with those 4 way PVC pipe connectors would work. Just need a base and it would work a treat. Could be the new JT65/WSPR antennas if this style makes a comeback.
If you look at Franks page, he built one for 80 meters and one for 40. You could scale it up more and get to 160 I suppose. I will be re-visiting it whenever I can afford to purchase raw materials and build it cleaner.
Great project ! I’m interested in building a larger loop with a linear loading
Kevin.........Wooden yardsticks from home depot & lowes are inexpensive materials to use for building magnetic loop antennas. You can also combine them with plastic rulers. Another advantage is you have the markings on the above to make accurate construction measurements. I also use nylon nuts & bolts.
Unfortunately my Lowe’s doesn’t carry the yard sticks anymore
Kevin, I enjoyed watching the video (again!). I'm trying to find the variable capacitor that will work QRO. I have a session with an Elmer on 2 April. I plan to ask him for more guidance. I'm still enjoying my EFHW 40m antenna. I have used it on 40m, 20m, 15m, and 10m. 15m was questionable, but the others were fine. I know that 15m isn't a harmonic of 40m, but I couldn't resist giving it a try. 73 de David AE4LH
Hi Kevin. That was a very interesting video you have made on the wire diamond loop. It has a wide bandwidth with only wire as the antenna. What would the difference be if it was made using like example 10mm dia copper pipe. Would that increase its efficiency ?. It crossed my mind has from what you have previously said about larger loops and their tube diameter. Just wandering ?.
73 and carry on the good work. de G0WXU - John
I would do a half-lap on the two pieces of wood so easier to get the same plane on both sides. Also I have some sort of plastic material from a old sign that is 1/2" think. I think that would make a great support for either a magnetic loop or your spirial loop,
What is the range of the capcitor?
Thank you. I bought some variable capacitors at a ham festival. would you purchase a capacitance meter to know the specs or you would simply plug and experiment with them?
You can get meters pretty cheap these days, and there's nothing wrong with going that route. But you can also just experiment and see what happens. I have more fun with the latter approach.
Kevin thanks for the video sir, what pF capacitor are you using sir? 73s NS9T
If the bandwidth is ten times, this is a resuly of ohmic losses. The antenna will have only one tenth the gain. In other words, -10dB gain.
Totally off base, but what is your computer hardware spec you're using for the RSP1A..?? I'm Minimalist at heart and trying to find a gud PC reformed maybe that doesn't lag.. Thanks for all your videos, especially mag loop my next Antenna project, living in a Studio Apt at 3rd floor. Old cement bldg. Hope it will fly 😂 N7PB Paul OldNormanBates Seattle WA cn87uq RememberTubes ©
Great video!
I always enjoy your videos and v blogs.
Would the bandwidth increase if a thicker wire was used )say 14 or 16 ga.)?
Thanks.
Maybe a tiny bit.
Interesting. Did you ever hook it up and try it on CW or SSB, perhaps outside?
Thank you.
Hello! Interesting construction indeed! The wire diameter is critical for transmision, as I can understand from some previous comments. I'm quite new on this hobby... The wire should be thicker for more power, right? I am about to use 10W SSB with 1 mm wire diameter. What do you think? YO8UFO, SK.
If you were to make an 80 mtr version with pure copper wire. Could you tap the turns & have an 80-10 mtr loop? Maybe even 160 mtrs?
Can one build this but at a larger diameter using same length wire to get more gain?
Kevin can spiral loops be made directional like a quad?
Looks like a Biscay Cross antenna, the German U-boats used to detect British aircraft radar.
How large would this antenna have to be to work 20M without a tuner?
I hope to be at this level someday.
Elsewhere in comments someone stated that the smaller the antenna & more loops the greater the losses and decreased performance -- so if I used the same amount of wire but increased diameter of loop, so as to have fewer number of loops, would the antenna work better?
They're talking about the resistance of the outer loop. If you use the same amount of wire, the resistance will be the same. The web site I link in the description has more technical information on the spiral design.
Thanks, Kevin; for all your videos. This one was most useful to me. I am babysitting a vacation home
in the Catskills and I don't want to put holes in my buddy's home so for 10 watts or less the spiral loop should do the trick. Was considering a non spiral loop until your efforts shows that the bandspread is quite a bit wider on the spiral wound loop.
Best wishes,
R Mike @ KC2WVB
is this spiral loop antenna good for transmitting or just for receiving if you can transmit using this antenna what kind of power level can it handle?.
Yes you can transmit, I did in this video for the WSPR testing. Power would depend on the voltage rating of the tuning capacitor. Certainly safe at QRP levels with most caps, maybe upwards of 10 to 20 watts with most air-variables.
Great job! Love it. 73 KF7VUT
I want to try POTA with one of those. Looks simple and nice small size.
They wouldn't get out as well as a simple end fed wire would.
@@loughkb So they are basically a small antenna for limited range. I wondered that because many pictures of them are in a military setting for talking 100 miles or less. Maybe longer on a hill.
For a spiral receiving loop antenna for indoor use......Can solid 20 guage aluminum or galvanized wire be used?
For a receiving loop, you can use any kind of wire you wish.
1:40 Swedish operator, I see! (I am Swedish too.)
Where are u connecting since antenna
Dumb question. Can an antenna tuner be used in place of the capacitor for outdoor mounting of a similar antenna?
antenna tunner is just some variable inductor and variable compacitor. Usually those type of loop is compromised antenna, they have very small bandwidth, you might even need to adjust tunning everytime you change few khz
@@769270865 Okay, thanks
@@OkieRCguyYes, you use can use an antenna tuner. The range of the main capacitor is large, and you don't want to use a (far away) to correct a large mismatch. You may be able to tune the antenna to e.g. 14.1 MHz and then use your tuner to use the antenna from 14 MHz to 14.2 MHz.
Best SWR I can get on mine indoors is 3:1. Hopefully when i can get it outdoors with less interference it will improve. Might need feed loop adjustment still.
Interference noise isn't going to change the SWR. Nearby metal objects could affect it though.
I'm pretty sure it's the aluminum siding. I've had similar issues with my indoor 2m antennas if I've placed them too close to an exterior wall.
Love the video! What are the specs or range of the capacitor
The original design linked in the description has the desired spec. The cap I was using had a range of around 9-130pf.
@@loughkb thanks again
Is 20 gauge brass wire ok to build a spiral loop for receive only?
Just about any wire will do fine for RX only. The radiation resistance problem only applies to transmit.
The way you stripp the wire is the right way. :) I love using wire cutters instead of wire strippers, because wire strippers a large and really don’t work that well. Oh and I use my fingers too, sometimes
Are you able to transmit with this antenna or is it just listen only
Yes, you can transmit.
Keven try a 2 mtr or 70 cm moxon antenna cheers kg6mn
Why didnt you start from the inside?
The following may sound like a dumb question, but my experience with antennas is dipoles and 1/4 wave verticles. Could your loop be used with an antenna tuner on frequencies in the 17, 15, 12, 10 and 6M bands?
How's about 30, 40 and 60 meters with a tuner?
Also, re your back though we don't know what the problem is, maybe this outfit in Pittsburgh Pa, can help. And no, have not required any back related treatments thankfully but I hear good things about the practice. www.americanbackcenters.com/
Take care and 73
John KB3SVJ FN00fq
Hi John, No, you wouldn't use an antenna tuner with an antenna like this. This antenna is a tuned circuit already. You could change the frequency range of the antenna by adding or subtracting a turn and changing the capacitor. If you look at the page I linked, you'll see his antennas for 80 and 40 meters.
OK, thnk you!
How far away can the capacitor be from the base of the antenna?
It needs to be right at the antenna. If you ran it very far, the connecting wires would act like a capacitor themselves. Also, you want a low resistance between the antenna and the capacitor, so as little wire as possible.
Hi, Kevin, this antenna is for TX to?
Yes, I was transmitting on it during the tests with WSPR.
And ssb ?
Any mode you like, I can't see why it would matter.
Kevin Loughin thank you
Nice one for cliff dwellers in flats ect g0myd
Can metal nails on wood affect antenna operation?
Not enough to matter, probably not even enough to detect with test gear. Just not enough mass to matter much in a nail.
Hi dear friend. Please send to me d plan o how es d sized x 40 meter to 10 meter a can make one by me self ok att. Radio user. Thank u guy
Why not measure the various loop sizes, add them together for a general total size
and cut it to length to obviate the need to weave with that bird's nest?
That single turn design is the basic magnetic loop antenna. The reason they used this spiral design was to reduce the area to make it physically smaller. The trade off is performance.
Start the winding from the inside of the loop, then there is not passing the bird's next through . . .
It is easier to wind from the inside turn out.
Is pvc that expensive in USA ?
Wood is very cheap in the USA.
I liked. Pena que eu não falo inglês , contudo entendi perto de 70%
Made a spiral loop. Seems to work on 40 and 80.
KG7IRJ Ohio.
🇧🇷🇧🇷🇧🇷👍👍👍
Standing in a room full of expensive professional-grade tools and electronics: "yeah I can't afford to get PVC"
People's situations change in life.
I thought that was rather odd myself.
Spiral loop = Coil
Finally a ham operator that doesn't look like a pencil neck geek. 😁😂
Why didn't you start from the inside. That would have saved you a lot of trouble.
Yes, that old saying, "Hindsight is 20/20 vision" is actually true. We all get that.
"Can't afford to go out and buy some PVC." A five foot section of schedule 40 PVC costs less than $10. Sorry you have fallen upon hard times.
You cannot afford just go out and buy some PVC. WTF? Don't feed us the BS, rather it is better to straight up mention your Patreon. You probably are more comfortable doing so in 2021 and may alread do it. But that PVC BS was not subtly executed by you. I mean, you mentioned three times in a short duration that also included a scene change.
I'll ask just to be fair. Was PVC really not affordable to you in 2017,.