Magnetic loops

With high power transmitters, magnetic loop TX antennas often require special capacitors for tuning as the voltages can be high if these antennas are efficient. With QRP this is not the case and great success can be had with "ordinary" parts.

I have been amazed in the past how well they work, especially considering how small they can be. The secret is to use thick wire, ideally copper pipe or coax for the coil. For modes like WSPR, FT8 and PSK31 where big changes in frequency are not needed, these can be perfect.

See https://sites.google.com/site/g3xbmqrp3/antennas/magloop