These are some really compromised magnetic loop antennas. They don't use the ideal low loss materials for them or they may be far smaller than is efficient for their design frequency.
Still they may still be useful for receiving and certain applications where top efficiency takes second place to size or easy construction.
Laptop bag magnetic loop for HF WSPR
This is my smallest magnetic loop. It's made from aluminium strip. This is bent to form a rectangle that
fits perfectly inside a laptop computer case. In conjunction with this and an HF transceiver you can send and receive
WSPR signals over hundreds of kilometres. Videos describe loop and demonstrate its usage even when from inside a bus.
Bicycle wheel magnetic loop
Copper is the best material for magnetic loops. Closely followed by aluminium. A bicycle wheel is neither.
But I tried it anyway as I had one on hand. Video below describes my results when transmitting on WSPR.
Figure-8 two bands at once magnetic loop
Normally a magnetic loop is resonant on one frequency at once. This one works on two frequencies, in different bands, at once.
While not efficient on transmit this may have certain applications like digital modes receiving of signals on two bands.
Speaker wire magnetic loop for 15 to 10 metres
This is not not efficient. It's fine for WSPR transmitting but I'd imagine that you'd have a hard time making contacts on
SSB with it. Still it's a fun experiment. Video describes the loop and includes demonstrations from home and a local beach.
Kitchen foil magnetic loop for 15 to 10 metres
This is another loop I built just because I had the materials available. In this case kitchen foil and a kids hula hoop.
It works OK but be aware that the foil is thin and might not stand the high voltages encountered on loops. So use this
design only for receiving or very low power transmitting.
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