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Choice of antenna solution

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wimquist

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I'am working on a hand-held with a 2,4Ghz antenna on it.
We have problems with the quality of the transmitted audio packet. so we try to make the receiving signal better.

Our module has the possibility of antenna switching to choice the best receiving antenna.

What type of antenna is the best options and what will you suggest. because of the antenna switching i can place 2 different antenna's.

Is it the best to use ifa,openloop,stub or patch antenna?
And what is the different in receiving quality between them?

This is my first 2.4Ghz project so there are a lot to learn.
 

biff44

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Hand held uually means the person can move it around to ANY position/orientation. That means that you can end up with corss polarized antennas for transmit and receive. So if you made your transmitter antenna to be dual or circular polarized, and the receive antenna was one polarization, you could remove that 15 dB or so of cross polarization loss that you have to make up for in system gain. You do take a 3 dB loss off of the best system gain you could have with that approach.

Try an experiment...go out to maximum range and rotate your hand held device so that you go through co and cross polarization. See if holding at certain rotations gives you much greater range than other orientations.

Another issue...it is hard to get omnidirectional coverage in a hand-held device. This is because your hand will change the antenna radiation pattern. Also, the electronics on the PC board will also change the antenna's radiation pattern. So 2 antennas with different radiation pattern orientations might help too.

Give us more info, is the hand-held device receive-only? How big?
 

wimquist

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There is one RF input output for RX and TX. the switching between antennes is made wit a BAR64 RF switching diode. the antenna with the highest RSSI is selected automatic with with the module.

so the best way is to use 2 antennas that stand in a hook of 90degrees?
 

jongjong

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i strongly suggest PIFA and texas Instrument IFA. best result for us in bluetooth transmission thats 2.4ghz both are 50 ohms so fine tuning needed only. by the way, use CST MWS to simulate antenna. perfect for fine tuning your antenna.
 

wimquist

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oke i'm gonna design 2 pifa antenna's and test of my signal is better.
 

jongjong

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PIFA antenna needs to be tuned always. it always depends on your grounding.
 

wimquist

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the tuning is done by changing the length of the long trace of the IFa antenna? sometimes called L?
 

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