Most people use an electrically-short loop antenna that is resonated
to operate at 400 MHz. There are a number of application notes on the
web for RKE (remote keyless entry) devices that have antenna design
equations. Look at companies like Linx Technologies, Maxim, Micrel,
Xemics, Melexis, Chipcon, etc. that make devices operating in this
frequency range.

Mark

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On 15 Feb 2004 10:08:23 -0800, (erdem) wrote:

I am looking for microstrip antennas that work around 400Mhz, and can
fit into a key chain. What I heard is; car starters, lockers all have
these kind of antennas, but I cannot find any place who sells these
things. Could you guys help?

Thanks,
Adam

Mark