Loop antennas are becoming increasingly popular as more radio fans find they can’t erect elaborate outdoor antennas. Like most things, of course, there are trade-offs. But, most often, loop antennas are for receiving. Only a few can handle transmitting, and [FesZ] wanted to build some that could handle transmit power. You can find out what he discovered in the video below.

Loop antennas are very sensitive, and a standard variable capacitor just rotates less than a single rotation. High-precision devices would often have gear reductions, but those are hard to find today. But with a 3D printer, it is reasonably easy to make gear reductions for a variable capacitor, and that’s what [FesZ] did.

In addition, [FesZ] replaced one non-critical capacitor with a bank of fixed capacitors and switches. This isn’t just a build video. There are Spice simulations and even a thermal camera deployed. A lot to learn.

If you build some cool loop antennas, let us know. If you want to look at some commercial receive antennas — including one that is — sort of — infinitely long, we’ve tried a few.