The 40m Magnetic Loop Update

Sat down last night and started to work on the 40m Magnetic loop antenna. I have had the parts for this for a while but have not gotten around to building it yet. I hit a snag right off the bat. I had bought a 25ft piece of terminated RG-213 but when I unwound it found that it was closer to 28ft.That put the diameter at closer to 9 feet in diameter rather than 8ft. Of course I have no connectors to shorten the cable handy…sigh. OK, so now if I have to reduce the size of the cable I am thinking a making the loop about 6 feet in diameter. This will give me a bandwidth of 12kHz and an efficiency of 32%. I will need a cap capable of 2kV to mange 25W. Since the antenna is fixed for use at 40m The cap only has to be in the range of 60pF or so. I have ordered the connectors and will shelve this again until I can cut down the coax. This will give me time to think of the cap solution.


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