GM682: Switching between internal/external antennas

Wireless & IoT
1

I have a prototype built around the Telit gm682 module with GSM and GPS. I plan to use internal antennas (in a plastic box), but would like to be able to support external antennas as well.

I don’t need to have both active at the same time, but would like to programatically switch between them. This implies I would have a software-controlled analog switch or relay to route the correct antenna signal to the gm682 module.

Does anyone know if this is feasible? Would the switch degrade the signal quality too much? And would this pass muster with the FCC if we ever needed to certify the antenna circuitry?

Also, if anyone has taken a product to market using the Telit module, I’d be very interested in hearing your experiences.

Regards,

Brett

2

You would definitely need a proper RF switch IC. They’re fairly easy to use, but you need to layout the board they’re on right.

Skyworks makes some.

Cheers,

–David Carne

3

Thanks for the tip. Looks like Skyworks has 2 chips that should do the trick (AS196-307 and AS193-73), and they’re reasonably priced (single unit prices $2.09 and $0.92). Just ordered some samples, I’ll post back to the forum once I have a chance to test them out.

Thanks,

Brett