CB is potentially a good choice for folks that are not licensed amateur operators if they use directional antennae and phase the antenna for horizontal polarization instead of the normal vertical antenna. I am thinking base to base operations here. Using antenna with horizontal polarization can attenuate signals transmitted by a vertical antenna by 20 dB . Every 3dB of attenuation cuts the signal by 1/2 so that would be 1/64th or slightly less signal power! [JWR Adds: The means very low probability of intercept by anyone outside of your private family or survival group “horizontal antenna network”! That suggestion just earned you a Blinding Flash of the Obvious (BFO ) award. Yes, I know BFO means something different to hams (Beat Frequency Oscillator), but here at SurvivalBlog it means that I like your idea so much that I’m sending you a free book to thank you for it!]
A Yagi-style antenna can give 10 or more dB of gain. That means the effective radiated power of a 5 watt radio (which is actually about 3 watts) is ten times more or about 30 watts in this case.
Propagation can cause skip signals to give interference. The antenna should be a minimum of 1/4 wavelength above ground for best results. A directional antenna can be something like a flashlight [beam] if chosen properly. It can send and receive signals from the direction of choice and attenuate signals from other directions. A cheap wire antenna beam is called a Moxon beam  [, named after the late Les Moxon, call sign G6XN.]
A ham license [in the US] is now so easy to get that people should just get the ham license and that will open up more bands and allow the right equipment for the situation. See www.ARRL.com  for testing locations and times.
The first level ham license is the Technician class. To quote a recent ARRL article: “Some Technician licensees who gained new privileges on February 23, 2008 remain unaware or uninformed as to what they may and may not do on the HF bands”, says ARRL Regulatory Information Specialist Dan Henderson, N1ND. In addition to all Amateur Radio operating privileges above 50 MHz, Technicians who never passed a Morse code test now have CW  privileges on certain segments of 80, 40, and 15 meters plus new CW, RTTY , data and SSB  privileges on certain segments of 10 meters. And that’s it. “Know your privileges ,” Henderson advises all Amateur Radio licenses. He says some Technicians apparently believe their new HF  phone privileges go far beyond what they really have. “Technicians have no phone privileges on any HF band other than 10 meters, period!” Henderson emphasizes. “That’s the bottom line. If you want to operate phone on the other HF bands, you’ll have to upgrade to General or Amateur Extra class.” [The good news is that there is now] no code test for any class of license now! However, code can get the message through poor band conditions when voice is impossible.
A digital mode called PSK31 can, with a laptop computer and a low power HF transmitter, communicate under severe band conditions even better than code! Technicians have phone privileges from 28.300 to 28.500 with a 200 watt power limit. When band [signal propagation] conditions are good, California can talk to the UK on 5 watts. Band conditions for HF are poor right now [because of low sunspot numbers] but there are always openings on the various bands due to changing conditions. I called a local Boise station last night on 75 meter phone using 10 watts and was answered by a Southern California station, but at the same time a Northern Wisconsin station with a super antenna farm was having trouble hearing me with 100 watts power. I hope that this has not bored you to death.
See QRZ.com  for practice tests and a search engine to locate a ham radio operator in your zip code to contact for more information. 73s, – The Other Mr. Delta