Using digital techniques has caused a resurgence of interest in VLF — very low frequency — radio. Thanks to software-defined radio, you no longer need huge coils. However, you still need a suitable ...

In these low-frequency bands, the signals are not heard in loudspeakers or headphones, or rather, the emission of sounds could occur but it is not the main activity, as is normally the case on other ...

Magnetic loop antennas are great if you are limited on space since they are just a potentially small loop of wire. The problem is, they are sharply tuned. You normally have an adjustment capacitor to ...