SIM900 antenna troubleshooting (short to ground?)

Getech shield

What ohms should I be seeing at the external antenna jack? I'm getting 0.1? between the center of the jack (or SIM900 pin60 RF_ANT) and ground. Is that correct or a short?

I've got my shield running software fine but the signal is weak. Even with the provided external antenna, my cheap-o cell phone on the same network gets better reception and can register to the network in places where my shield cannot.