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
B@tto 51 Posted May 7, 2014 Author Share Posted May 7, 2014 Some news about CC1101/CC430 lib : I'm just getting crazy xD yesterday I used my watch to drive a lamp at my home. Was OK but very limited range (~1m). So today I decided to optimise it, but nothing works now. I tested a lot of configurations and that means nothing. Sometimes signal is received, sometimes not ... I just give up for today, I'm done ! Quote Link to post Share on other sites
jpnorair 340 Posted May 7, 2014 Share Posted May 7, 2014 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. Cool. The stock Chronos 433 antenna is absolute rubbish, though, so it is a low bar. In any case, I can mail you a hand-built ~5cm reference monopole, if you want to compare RSSI readings (send me a PM). I have tons of these, which I manufacture in the lab. Normally I don't offer this sort of thing, but you are actually working on something that is of interest to me. The same offer goes towards anyone doing 433 MHz Chronos work, or for that matter CC430, CC11xx, and CC1200 work. It's also important to mention that a single-ended antenna (monopole) needs a decent-sized ground plane to work properly. The Chronos doesn't offer this, but if it is plugged-in to a USB cable or some other path to mains-power, this will serve as an excellent ground (even plugged into a battery powered laptop, smartphone, etc, this is plenty of grounding). As soon as you remove this ground, the antenna performance will get much worse. Ideally your ground plane on a monopole configuration has radius of quarter-wave, but if you don't need wide bandwidth you can hack a decent antenna system just by having the perimeter of the ground plane >= half-wave (in this case, you are actually building a dipole). timb, abecedarian and Automate 3 Quote Link to post Share on other sites
adrianF 43 Posted May 21, 2014 Share Posted May 21, 2014 Hey all! This is Adrian from TI. We absolutely love this effort! To show our support, we'd like to enable you folks with some CC430 Chronos dev kits to help you out! Please send me a PM with your preferred shipping address & we'll send you a Chronos kit ASAP! Thanks - we love the Energia project and I may or may not be wearing a Chronos watch right now Cheers, Adrian timb, bluehash and kahva 3 Quote Link to post Share on other sites
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