timb 15 Posted May 7, 2014 Share Posted May 7, 2014 How did you design this antenna? Using a helical winding is a difficult way to build an antenna. You need to determine the impedance and make sure that it is the proper terminating impedance, which is largely an experimental process. Generally speaking, however, the total uncoiled length of an inductively loaded wire antenna is quite a bit longer than the equivalent straight-wire antenna. I based it on a commercially available unit that I got the specs for, I then tweaked it using an antenna calculator. 5mm inside diameter, 17 turns at 34mm length. I'm sure it's not perfect, but I'm confident it's as good as the OEM antenna, which is just the top metal casing that goes over the watch face. Quote Link to post Share on other sites
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