Wow, I better speak up here too for the record. I have been a HAM for 12 years now and into all forms of communication and monitoring for over 28 years including building many "home brew" antennas and studying radio wave propagation since I was 10 years old.
A properly installed and matched external antenna on your vehicle will make a huge difference in both receiving and transmitting for all types of communications regardless of the radio type: CB, FRS, HAM, CELL, etc...
BUT if you don't want to take our words for it, go and get one of the books at the following, VERY TRUSTED IN THE AMATEUR RADIO COMMUNITY, link if you want to fully understand why an external antenna is way better:
ARRLWeb: ARRL Product Catalog
I have ran mobile 2m/70cm antennas on my off-road SUVs’ now for over 10 years and as for an antennas I like and use both the Comet SBB5 and the Diamond NR770-HA. Both are recommended by the manufacturers for off-road use and come with a fold over feature where you can pull up on the antenna then lay it down flat to gain clearance.
My best piece of advice to all non-licensed aspiring ham off roaders that read this is to not rush into it, do your research, talk to experienced off road hams to see what works and doesn't work then just go buy a radio and antenna and get the dang thing installed with or without a license. YOU CANNOT LEGALLY TRANSMIT ON IT UNTIL YOU ARE LICENSED but it is perfectly fine to monitor it. Just unplug the PTT mike and toss it in your glove box until you are licensed or there is some sort of extreme life threatening emergency and there are no other forms of communicating. If you decide to transmit on it without being licensed, emergency or not, you will be subject to disciplinary action from the FCC including fines and being banned from being able to get licensed and that's something I'm sure nobody here would want.
Now I'm sure that there will be responses to this post suggesting otherwise but they should understand that most people here that talk of becoming a ham do just that, talk, talk, talk! Having that cool radio in your rig and listening to all the action on the local repeaters, nets, contests, etc... will surely motivate them to get a move on and take the simple test to start using it. At least that worked for me...
