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Multiple gsm modules, one antenna

  1. Sep 3, 2009 #1
    hi everyone, a friend of mine bought a multi-sim iphone clone from china. i was so amazed at this. as a hobbyist, i want to create my own pc-based multi-sim gsm terminal. so i want to use 4 gsm modules(sim300). one for each gsm-provider here in my country. but my problem is i want to use only one antenna and the four modules share on this antenna. just like the iphone clone of my friend. im pretty sure that it uses 2 modules but these modules share on just one antenna. can you guys share your thoughts on this? how can i do this? thanks in advance
  2. jcsd
  3. Sep 4, 2009 #2


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    Science Advisor

    The module you describe would have taken many hours to develop, even with specialiised test equipment and expert, experienced designers.

    Tuned circuits at such frequencies often take the form of a small piece of printed ciruit board track. A quarter wavelength at 2400 MHz is 31.25 mm. If it was made 30.25 mm long, it would resonate at 2479 MHz which is 79 MHz higher. That was only 1 mm shorter or 1/25 ths of an inch.

    If your friend got a good deal, you might like to do the same.
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