![]() ![]() His general form of the equation in the link above contains factors for other geometries - I've seen a few people make hexagonal and ocatagonal loops, but I assume the majority are making square. A is the length of one side of the loop in cm.The Joe Carr's Tech Note formula approximates rectangular loops provided that the aspect ratio is not too large. Bottom line, throw in the inter-winding capacitance and you have some experimentation to do. ![]() So which is right? Both are - they both did a lot of research and obviously have supporting data for their formula. , which happens to be pretty close to the UMR-EMC result. If you increase the number of turns in the Joe Carr calculator by 1, it produces 296.70 mH ![]() I pre-loaded a 3 foot ribbon cable loop into my Javascripts, and: It would be very nice if they produced the same result, but they do not. There are two sources of equations for the inductance of the loop given below. Rectangular and square loops are easy to construct, being built from wooden crossbars, wooden frames, attached to doors, or even made of PVC pipe. Surprisingly, I get the best results by adding more turns to the loop so I can use the newer 9.6 to 250 pf tuning capacitors. In practice, this is sometimes a challenge because the AM band tunes over a frequency range that is 3:1 (1700 / 540 = 3.15). Ideally, the fully meshed position of the tuning capacitor should tune the loop antenna just below the lowest frequency in the desired band, and the fully open position of the tuning capacitor should tune the loop antenna just above the highest frequency in the desired band. The problem for loop designers comes in designing a loop with the desired value of inductance for their tuning capacitor.
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