I Built a High-Q Magnetic Loop Antenna from 10ft Copper Pipe! In this video I walk you through building a real magnetic loop antenna in the garage, talk about why these things have such high Q, show how it performs on the air, and give you my honest thoughts after using it. From Oklahoma City with just 20 watts on my Xiegu G90, I worked Vancouver, Washington — almost 2000 miles — and got a solid S9 +10 report. The audio quality was fantastic and the antenna is surprisingly efficient! Parts List (Loop Only) •10 feet of M-class copper tubing (cut into 14" segments) • 8 x 45° copper elbows to make the octagon • High-voltage variable tuning capacitor (I used a Johnson air variable capacitor: model 154-9) • Short copper strap/braid for capacitor connections • Small coupling loop (~8-10" diameter) with SO-239 • Non-conductive mast/stand How I Built the Loop Cut the 10 ft of M-class copper into 14" straight pieces. Connected them with 45° elbows to form a big octagonal loop. Left a gap at the top and connected a variable capacitor with short, fat copper straps. Built and placed the smaller coupling loop inside (about 1/5 the size). Mounted the whole thing vertically on a simple stand. The Verdict This was a super fun project and the antenna works really well. It would be perfect for HOA or apartment dwellers because it’s compact and has great noise rejection. Sound quality is excellent and it’s very efficient on the frequencies it’s tuned for. However, it won’t be my daily driver because retuning with the NanoVNA every time I change frequency is kind of a pain. I’m already working on a Raspberry Pi auto-tuner that should fix that — that build will be in the next video! If you like to stay on one frequency (POTA/SOTA activators, nets, etc.) this thing shines. High-Q magic in action! Drop a comment if you’ve built a mag loop or if you want the auto-tuner video next. 73! WY6Y
Yup, my first impression after building one was these antennas perform better than you might think... Even when using QRP power, its performance was unexpected and surprising. These are not difficult to construct. I constructed one on a lazy Sunday afternoon. I just tune it by ear. I peak the background noise on the radio and when transmitting, the SWR is pretty close to perfect. In some cases, minor tweaking is all that's usually involved.
Thanks for the comment buddy. I tried tuning by ear, but I think my air caps might be a little wide for this loop. I had to really dial it in to get it just right. Somebody I talked to told me about adding a second air caps as a trim caps, but I think I'm just gonna go the Raspberry Pi route. Working on that right now. 73 WY6Y
I installed a reduction gear on the tuning capacitor shaft. This provides more precise manual tuning. The tuning wand for the capacitor was salvaged from a window blind.
Your loop will work even better if you roll the copper tubing into a circle and eliminate the elbows and soldering. Since I only run QRP, I added a simple SWR indicator to my loop that will show if I'm zero'd in or not: https://qrpkits.com/miniswr.html Have fun!
Hey buddy. Yes, I tried bending it at first, but geeze louise, it aint as easy as it sounds. Some suggested heating it or adding sand, but I just went with Octogon. 73 WY6Y
To be more specific using images... Cut "hollow" window blind wand to any length you desire.... Implementation: And this is how I tune my magnetic loop antenna. The reduction gear ensures tuning is very smooth and precise.
