People have long been interested in very low frequency (VLF) radio signals. But it used to be you pretty much had to build your own receiver which, luckily, wasn’t as hard as building your own VHF or UHF gear. But there is a problem. These low frequencies have a very long wavelength and, thus, need very large antennas to get any reception. [Electronics Unmessed] says he has an answer.

These days, if you want to explore any part of the radio spectrum, you can probably do it easily with a software-defined radio (SDR). But the antenna is the key part that you are probably lacking. A small antenna will not work well at all. While the video covers a fairly common idea: using a loop antenna, his approach to loops is a bit different using a matching transformer, and he backs his thoughts up with modeling and practical results.

Of course, transformers also introduce loss, but — as always — everything is a trade-off. Running hundreds of feet of wire in your yard or even in a loop is not always a possibility. This antenna looks like it provides good performance and it would be simple to duplicate.

Early radio was VLF. Turns out, VLF may provide an unexpected public service in space.