Video

A mag loop radiates in the same plane as the loop with nulls 90 degrees to the plane of the loop. Does this still apply to the vertical and how does this apply to NVIS work?

OK but does this not also apply to the linear application as you are suggesting unless you have found foil in sufficient length and width to completely cover the 4 inch plastic pipe without overlap or creases.

I love your method of achieving the tuning capacitor both cheap and efficient (great Idea)

What about wrapping the foil tape around the plastic pipe rather than the straight or linear application

The presenter lost me in Pennsylvania. I was interested in the product.

Thank you. ✅

Are both Manganese-zinc ferrites and Nickel-Zinc Ferrites magnetic?

Is there any way to get the slides? Max zoom on a 34 inch monitor and its still a blurr

I wish I had professors who present as skillfully as you do.

Nice chat on vehicle antenna placement!

Your formula for inductance at 32:33 is wrong. It should be L = 200/6.28 x f

This was great! I built two test devices. One, I call a common mode current probe, which is the split toroid with analog meter. Then, I built another with two split toroids to connect to each side of the current choke. They both connect via coax to my meter which has a port A and port B switch. The idea is to set the sensitvity of the meter to full scale while sampling port A, which comes from the antenna. This is becomes a reference point. Then switch over to port B, and monitor the common mode current after it leaves the choke. I will post a video on the consturction and demo soon. Every radio operator should see your video!

At the Hamcation in Orlando today I was told to try a magnetic loop antenna so I asked if my 1969 ARRL handbook would have magnetic loop antennas listed. Heading for my book shelf!

73 from Münster in Germany. I'm really impressed. Great tweaks. Why is there no balun at the feeding point?

Wow! What great insight,

Very inspiring and instructional video, finally some real facts and analysis have been shared around the loop antennas. I was wondering: Is the use of a commom-mode (or balun) necessary at the entry point of the small loop an option, in order to minimise any potential interaction (i.e. loading/detuning/currents on shielding, etc) of the coaxial line to/from the radio with the main loop? tnx, 73!

OK we've completed the 4FT version but we used 2" PVC.. I'm not sure about what the wiring needs between the antenna and my PlaySDR srcdx. What do I use to power the antenna? I can see the capacitor makes some difference but I'm unshure how to tune the bottom clamp.

Mr Fortune, thank you very much for sharing your design with us. When my daughters and I complete our Magnetic loop we will send you photos. You are very kind.

I’m very confused. When is a choke a balun and when is a balun a choke? They are two different things and have different purposes.

When using the Toroid Calculator - what gauge insulated and non -insulated wire are they using for their calculations?

Great presentation, John I love hearing opinionated speakers who can back up their opinions. I'll have a got at these sometime. Gareth, M5KVK

Non of these lectures tell you what kind of ferrite to use for true high power operation. Ask any Winning contest station and they will tell you to get rid of all ferrite material that is used in the transmitting circuit. 99.999% of all ferrite material is used for RF suppression suppression

This video would be a lot more interesting if you showed us how you measured each side, showed how you actually connected the coax, showed how you made the tuning device, etc. Unfortunately we don't know how you measured it. We don't know how you hooked the coax to it. We don't know why you didn't use a small loop inside it. We don't know how high you have it off the ground. In fact you didn't inform us of much of anything at all other than the shape . Very disappointing

Basically, there is no good mag loop antenna in typical sizes. Just different degrees of bad loop antennas. I get it, it’s a compromise, it’s small, “but I live in an apartment or HOA”, ect…. If it’s all you can do, it’s all you can do. No judgement. If you want better efficiency, multiple bands, no tuner needed for applicable bands, cheap, and you can fit in your pocket or at worst a small bag, get an end-fed half wave.

I have used ferrite cores to wind impedance transformers. I learned how to select the type of material from this CZcams. Always weak in this knowledge but knew the very basics. Keep up the good work! WA0QQX

What a great video. It solved the issues I have with the loop I made. Thank you

says at end u dont have to tune it. but yet he says u have to. so whitch one is it lol iam cornfused .

What's your perspective of the the Ciro Massoni Mag loop (either Midi or baby)?

will 7ft dia loop made with 2.5 inch aluminium tape work on the top end of 80,ie 3.775 megs?

I constructed a magnetic loop antenna tuned to 144.30 MHz in the 2 metre band. This was made out of copper water pipe of 22 mm diameter. The loop was square with external dimensions 156 mm x 156 mm. The necessary capacitor was formed by using a 22-to-15 mm "reducer" by which a short 15 mm pipe was inserted into the 22 mm pipe. Hardly a "variable" capacitor! The co-axial feeder cable was connected to a wire loop of much smaller size located inside the antenna. I used the antenna mounted horizontally a few feet above the roof of my car. This antenna worked very well (within the limits of the fixed frequency to which was tuned). My impression was that it was at least as good as a half-wave dipole. I had a QSO with a French station from southern England during a "lift". Frankly I wouldn't recommend it. Its function would be severely upset by rain, and the very narrow bandwidth is a great disadvantage. Also I was fearful of damaging the Tx output transistor by transmitting at a non-resonant frequency, hence into a gross mismatch.

Thanks for the video guys. In the 1950's, W1NJM(?) (no joking matter) Roger Hart ran a system of high speed contests at area ARRL hamfests by sending a reel-to-reel tape to a volunteer for the club sponsor. Competitions were held and awards given out in form of a certificate. Used to win them regularly. The contests fell out of favor, due to lack of ARRL support, as the years progressed. :-) Sad that the ARRL didn't sponsor, at any time, sending a team to EU. I also inquired about it and got the same budget answer. Oh. Roger got support from the Connecticut Wireless Association for expenses. At the time we weren't allowed typewriters, so pen and paper. So it got to be a memory buffer contest at the time. Everybody I knew from the era are silent keys. I am QRT after moving last year and downsizing with no antenna system. Good to see you on video Barry. dit dit Chuck, ex-K7QO P.S. My mentor was W3CVE, Red Barger, who was at the CIA until Dec 1961.

Trivia question: There were two previous sites for 146.34/.94 repeaters in Denver metro area. Where were they? Also, there was a previous ham repeater at the W0WYX site. What was it and how did it work? Bob had a regular column in the DRC Roundtable where he documented the comings and goings on Squaw, what the camp robbers (the animals, not nefarious humans) were up to and what birds were at the feeder. When the forest service mothballed the lookout, Margaret regularly commuted to Idaho Springs to work at the service's information center on Colo 105 and I 70. Lots of memories of long ago. Great to hear Dave (I remember him more as WB0BAE) and Rita who was the movie critic at 9news when I worked there. 73 de Craig KC0KP (formerly WA0WTG).

I am enjoying this discussion very much! Davey - KU9L

Oopsie John. Your formula for inductance should be L=200/(6,28*f)

First of all thanks for this wonderfull presentation ! But there's one thing i would really wanted to mention. We don't think about it a lot but aluminium oxidises very easy. The minute you stop sandind/filing it it will oxidise. Thats why you cant't solder it in the tradional way. I,m affraid the foil/pvc elbow method will induce al lot of junction-resistance. This wil negatively impact the "Rr". Maybe not measureable with a normal multimeter, but it will be noticeable with a dedicated resistance meter (for low resistances). I dont't want to split hairs here, but low resistance is key for magloops .. Best Regards and 73's

Very helpful thank you.

Found this Very interesting, surprised you only have one comment. Knowing about the skin effect, I have been wondering how a full wave loop in the diamond configuration fed at the bottom, with Rg 59 and 1:1 balun. Constructed out of copper tubing or let's say 1/2' EMT rigid steel conduit at 10-12 meters? Perhaps, PVC with your foil tape idea didn't think of that. On a side note; I happen to use an Alpha LM-400 Equivalent that has a Stranded center conductor, they advertise the Skin Effect, as well as its flexibility. 73

Rather than PVC pipe: what about perspex? One (or more) strips of perspex, 4 inches wide, with foil on one side (or maybe both sides). Carefully apply heat to bend the loop into the shape you want.

Can it using for mini hifi system

I have built this antenna with poor results. The use of PVC pipe degrades the antenna Q. The 2:1 SWR bandwidth is about 130KHz at 14, 18 and 25 MHz. This indicates a fixed lose due to the use of PVC. I have since read a number of articles about the poor performance when using PVC for inductors or capacitors.

Optimized!

Hi, I am just now looking into building an antenna for use on a bus I am converting to a mobile home. My armature radio use has been hindered since I got my license years ago due to stringent home owner societies that I did not want to fight in court to defend my rights. But on the motorhome would be my chance to finally use more than 2 meters. <LOL> and mag loop looks like the way to go. I do have 2 questions about mag loops though. 1) because of the radiation patterns of the loops being rather directional <ideal if you are trying to reach someone that you know the exact location of> and a lack of side side to the plain of the loop would it be ideal in keeping a low <close to the roof> profile if laid parallel to the roof and radiating 360 degrees toward the horizon? and 2) How does the tape used in this design stand up to the bakeing of the sun and the corrosive effect of the weather?

Is there an electrical effect of the different color PVC pipes? Thank you for the great presentation!

This went well until he got to the 49:1 "balun" part where everything fell apart. 1. A 1:1 balun was explained. There was no 4 or 9 to one described. Nothing! 2. The 49:1 is not even a balun, rather it's a transformer with a single ended output sometimes called an unun. 3. Choking is not something a 49:1 unun does. It is an impedance transformer. 4. The 200 ohm impedance number is far too low for decent choking action. 5. He uses 50 ohms in his calculations but you have no idea what the impedance of the common mode circuit being chokes is. This would depend upon the length of the coax and it could be in the thousands of ohms. The choke should have at least 1000 ohms impedance or more. Again...this is not a 50 ohm network. 6. Zip or lamp cord would have a much higher Z than 50 ohms. probably over 100 ohms therefore it would upset the impedance match in a 50 ohm system. It is better to use small, ptfe coax to maintain the correct impedance. So this video has a lot of wrong information in it. I'm not sure why. He repeated how "simple" this is a hundred times but in the end it's just confusion. The only part that is correct would be the 3rd wire of the coax part and even that was vague. Sorry to be so negative but you must be careful who you follow on these topics.

Hi, I have just finished building a magnetic loop antenna a week ago. I worked on this project for more than one year now. It is now completely installed on the roof of the house with remote control for the (30 to 250pF vacuum) tuning capacitor and hermetic enclosure for the snowy winter. The real McCoy antenna... There is just one problem, it does not work! It has a low gain, both in receive and transmit modes. I am writing this memo in order to get some advise. Please do not hesitate to comment on any incoherent aspect of my design. I am seeking help: The loop is made of one long 30 ft (10m) section of 3/4 in (2 cm) copper pipe coiled with no joint. The antenna diameter is 4 to 5 foot diameter therefore there are TWO turns spaced by about 6 inches (14 cm). The loop is connected to a vacuum capacitor and it tunes very well over the whole 80 meter band. At 3.8 MHz for example, the capacitance is around 120 pF. I don't think there is anything wrong with the resonance itself. But wait, the juicy stuff is at the end. The coupling loop is a simple wire about 20 inch (50 cm) diameter positioned in the same plane as the antenna, the usual way. I will not mention the Q factor nor SWR because I did not precisely measure it in a precise meaner, but I believe this is all normal: when I tune to a station, I can easily go left and right of the station and the SWR goes down to almost perfect 1:1 match. I repositioned the loop placement and saw no change. So, again I do not think there is a problem with the coupling or matching. My antenna has two differences with the most common antennas: i) it has two turns; that means that the radiation pattern is a pure magnetic mode. No interaction that looks like a folded dipole. The radiation pattern has the shape of a perfect symmetrical doughnut. (usual one turn antennas have a slightly directional "cardioid" shape. This can not be the case here because of the symmetric coil having TWO turns). ii) In order to avoid having to use a ROTATOR, I put the antenna IN THE HORIZONTAL PLANE. This way the radiation pattern is truly circular: no need to rotate the antenna... There are two problems with that, and here is the rationale behind that choice: 1 - The maximum transmission angle is horizontal, but the beam width would cover the necessary 15 to 20 degrees necessary. The antenna is mounted on a wooden cage about 20 feet (15m) above the ground. I believed I would get a nice over-the-horizon angle, good for DX. 2 - This is the part that I may have overlooked. The polarization of ground wave is VERTICAL, while our antenna has HORIZONTAL polarization. I am located in a semi urban environment with buildings, trees, electricity lines and hills all around my QTH. At the time I simply assumed that the polarization would quickly rotate to vertical. I drive this antenna with 100 W signal. I can barely go 300 Km BOTH in reception and transmission. From the same location, using a simple wire antenna and the same rig, on 40 meter band, everyday, I do QSOs all over across North America. In spite with the fact that I am a newbie, I never had a 80 meter antenna I really believe that antenna in not usable as it is.. Why? Thank you.

Great information. Simply presented. Thanks!

Resistive loss in the friction fit elbows are not optimal.

I thought 1 s Unit was 6 db

I spent the whole weekend building a loop accordong to your instructions. Each side is 1 metre and I have a wooden pole coated in aluminium foil which slides perfectly through the top section of the loop. I am blown away by the results ! 1:1 SWR on all bands 7MHz to 30 MHz but on 10 and 14 Mhz there seems to be no resonance at all. I will look in to why this is in the future. I can even tune it to the 5MHz band. Finally I can get signals out of my flat in a tower block and at last I can be heard on 7MHz. The bands have come alive ! A big thank you to John ! I will probably make a short video tomorrow showing progress so far. 73 de G4EYR

Excellent tutorial - can't wait to try this out !!!