Update: 'mdls' seems to be the simplest answer to this for MOV files (but not MP4 files, for which MP4::Info works ok.)

I put an extension on the cable of my cellphone booster, because a better spot for the antenna was a bit farther away than the 100' piece of coax that it came with. However, this seems to have made matters worse instead of better. In my experience in the past, all coax is more-or-less created equal, but maybe that's not the case when it comes to the frequencies involved here. What kind of cable should I be using for this?

Update: I replaced it with a single run of RG-6/U quad shield ("Belden 7916A"), and it works a lot better. So either I had a crappy cable in there, or connecting two cables together was a bad idea.