Magnetic Loops on HF
|10m band loop|
A magnetic loop can be a very effective HF antenna, especially when the very sharp tuning is not an issue. They can be very efficient but there is a trade between bandwidth and efficiency. They are ideal for modes that do not need frequent retuning such as PSK31, JT65 or WSPR. Ideally the inductor should be made of copper pipe or thick coax and the capacitors need to be low loss and high voltage types. Tuning is usually very sharp. Having said all this. quite decent results have been obtained with loops made of quite thin wire.
See https://sites.google.com/site/g3xbmqrp3/antennas/magloop .