E-field probe antennas

 

At VLF, LF and MF, external noise usually is the limiting factor.  Making the RX antenna bigger also increases the noise picked up, meaning that tiny RX antennas can be as effective as huge ones. This is the case with E-field probe antennas, that can be tiny.

Many years ago I made one on a mag-mount for 136 kHz so I could drive around trying to pick up my QRSS 6uW beacon. There are several designs around, some which are untuned. Much to my surprise, I could easily pick up my little beacon at 24km.

As the frequency is increased, external noise ceases to dominate and they become less effective.

You may find one useful for LF or MF bands.

See https://sites.google.com/view/g3xbm4/home/antennas/137khz-efp-rx-antenna .