Coiling a piece of wire that was formerly an antenna makes it into an inductor; any resemblance it has to an antenna at that point is purely coincidental.

 

That link was very useful to me. There's not much of a question here, but I'd like to outline what I'm going to try to do and if anyone here has any suggestions, I'd be happy to hear them.

I bought some MSP430-RF2500 development modules and have been fairly impressed with them. I'd like to make a multipoint network of devices in my house that work off of a single remote. The devices will be simple on off switch's or controllers for things like my fireplace (which require temp control), or dataloggers that report to the remote, like weather station...

I'm planning on getting some CC1101 transceivers with a matching 900Mhz Johanson Balun. I'll be playing with antenna designs.

Like I've indicated, I know very little about this stuff. As far as I can figure the best step for me would be to make up a bunch of designs and simply test them all out and tweak them until I get a range/coverage that I'm looking for. Unfortunately to test them, I really need to make up a whole new board for each try. I can't just simply make a bunch of PCB antenna's and plug them each in to try out, since they will have to be integrated into the board in final design that's how they have to be tested. This isn't that big of a problem. I won't have too much difficulty desoldering/soldering the main chips for multiple test boards.

Anyway, that's my plan. Any suggestions would be helpful, but I'm going to go through what I've learned so far from places like that article and the TI reference designs and simply experiment.

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Mark Higgins

 

The simplest antenna is a 1/4 wavelength whip (3.28 inches long) with a solid ground plane behind it.
http://www.rfm.com/corp/appdata/antenna.pdf
Might provide some good reading. If not heavy.

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Good article. It says basically what I tried to say. The gold standard is a ½λ diplole, or ¼λ whip over a large ground. Any shortend antenna is 10 to 20db worse. If you use shortened antennas at both transmitter and receiver, the loss is additive (not just another 3 db).

 

That was the same article from Post #3 in this thread. The one I referred to in my post.

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Mark Higgins

 

Sorry dirty, missed that, haven't been tracking this thread too close. If you want smaller than that you have to use a higher frequency or accept the wasted power and boost the voltage, small antenna's come at a cost. Your only other option is to raise the frequency. A 1/4 wave whip at 2.4ghz is only 1.2 inches long. Simply using a shorter antenna changes the feed impedance which changes your drive circuitry requirements.

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