Actually if this is the system you're talking about.....
San Diego-Imperial County RCS NextGen Trunking System Profile
www.radioreference.com
the answer is 'maybe'. The only thing you would damage is your wallet by trying it. You would need a jumper from the antenna connection to your scanner, but since it says '
850 / 1900 Mhz', it might be worth a shot. It might be quite helpful if it's a low gain type antenna; I see that system has some simulcast on it, and you don't want an antenna with a whole lot of gain on it, assuming you aren't using a SDS100 or 200
Mike