jpnorair 340 Posted February 23, 2014 Author Share Posted February 23, 2014 Most likely I will got for 433MHz. I just need to send a few bytes of data, like a string message with up to 20 characters. The Haytag boards looks great. Again, I wonder how they manage to fit the antenna into such a small form-factor. Any tips on the antenna design part? OK then, with that simple telemetry application, it gives you more freedom to make tradeoffs. With compact antennas, it is possible to trade-off bandwidth, efficiency, and size. There is something called "Chu Limit" for antenna size, which you can look-up if you are curious. The ISM R1 433 and 866 bands are quite narrow, so in these bands it is OK to have an antenna without large bandwidth. For your base station, mount it high if you can. If you feel confident building and matching a 5/8 wavelength monopole, that is a great choice for the base station. If not, then a standard 1/4 wave off-the-shelf monopole will work great. Just make sure the base-station is connected to mains if you use monopole, or even just grounded to some big piece of metal. Quote Link to post Share on other sites
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