Multiple gsm modules, one antenna

[overmindx]

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. I am 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

 

[vk6kro]

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.