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 ...

Ken Beckwith is a field engineer with EMF based in Nebraska. Being a hands-on engineer, Ken has done his share of construction over the years. One of his projects was the construction of an ...

The author is a consultant in Carterton, New Zealand. This follows up his December article “Tuned Bandpass Filter Is Solution to Backup STL.” Many years ago, the active whip antenna and the active ...

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 ...