There are several so called short or stubby antennas available. I purchases a slightly shorter universal version (one with several thread adapters) off eBay for my 09 Liberty. Shorter means a little less signal, but it also does not hang up in my garage door. They are a fairly standard screw in thread, no tools needed. Guys at the garage routinely unscrew them when working on the jeep.
Mangowalk 5" Black Short & Stubby Rubber Antenna Mast, about $13 with shipping.