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I've already designed a PCB with GSM/GPRS chip and also with RF 433MHz receiver only (without transmitter).

I would like to know if I can use the same antenna for both GSM/GPRS module and RF 433MHz receiver module?

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    \$\begingroup\$ Not easily, no. It's not just a matter of frequency mismatch, but also the difficulties of sharing when one part can transmit. \$\endgroup\$ – Chris Stratton Apr 25 at 17:41
  • \$\begingroup\$ You will find that most applications would use multiple antennas. They will try to keep antennas at nearby frequencies as far from each other as possible. Cell phones may have half a dozen antennas to handle all the bands. \$\endgroup\$ – KalleMP Apr 25 at 20:43
  • \$\begingroup\$ Thank you guys for sharing your knowlege, do you recommend using pcb trace antenna for gsm module? If so do you have a specific schema/ model? \$\endgroup\$ – Mehdi Apr 26 at 0:52
  • \$\begingroup\$ Another problem is that the 433MHz first harmonics may potentially end up very close to the GSM frequencies, on the 868MHz public "trash band". You don't want to get all that crap into your GSM transmission, so a narrow antenna is nice, not soaking up unwanted energy from nearby trash bands. (You'll obviously need band filters too, but this is something to consider.) \$\endgroup\$ – Lundin Apr 26 at 9:14
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Theoretically, you can design a multi-band antenna and use it for both GSM and 433MHz receiver. To combine the two radios to the same antenna you would need a diplexer, which could be implemented using a low-pass filter feeding the 433MHz receiver and a high-pass filter feeding the GSM radio.

However, if you have enough space, I strongly recommend that you use two separate antennas. It will be much easier to design each antenna and you won't need additional circuitry to combine the two radios.

For PCB trace antenna I recommended using the inverted-F topology (IFA). They are simple and relatively easy to tune. You should be able to find reference designs in the web.

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You can use either multi-band antenna covering GSM/GPRS and RF 433MHz or broadband antenna. But transmit and receive operation at same time is not possible with single antenna.

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  • \$\begingroup\$ This is effectively incorrect - it's not just simultaneous use that will not work, you need a way to keep the transmit energy out of the other receiver to avoid damaging it, and to avoid that receiver presenting an improper load to the transmitter. \$\endgroup\$ – Chris Stratton Apr 26 at 23:43

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