According to the loop calculators available online at various sites the efficiency varies as a function of a number of parameters but making one for 20 or 30M at 90%+ efficiency is certainly possible. The efficiency will likely be limited by the number or type of joints in the assembly including those in the capacitor used for tuning.
One which would be likely suitable for 30M could be made out of aluminum flashing as demonstrated by NV7E (i don't think he did his for 30M). It uses the overlapped ends of the flashing to form the capacitor. If tuned to a QRP watering hole it would certainly work either side of the tuned location enough to allow QSO off the calling freq. This aluminum flashing version wouldn't likely withstand serious weather but might make a great antenna for the attic. The higher the efficiency, the higher the Q but if you're rockbound, one frequency to get started while you're working on capacitor alternatives would seem to be a good start. 73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
