I have used a 14 element Yagi, and 300 milliwatts and worked a repeater that was Approx 140 Air miles from my location.
The repeater, the CVARC repeater was sitting @3700 feet overlooking the Central Valley area, and I was on the valley floor.
Capt has that 100% correct, Terrain has a HUGE influence on your coverage area.
VHF is Line of sight radio.Take that same power level and you might not be able to talk 2 miles in a congested area blocked by trees, buildings or hills.
If the Base antenna is sitting up on a hill, and the mobile is also sitting up in the clear, No problem.
If that mobile is sitting somewhere that is in the shadow of a hill, buildings, trees or other types of obstructions, not going to happen.
VHF Radio transmission requires a clear path between antennas known as radio line of sight.
Line of sight is the direct free-space path that exists between two points. Using binoculars on a clear day, it is easy to determine if visual line of sight exists between two points that are miles apart. To have a clear line of sight there must be no obstructions between the two locations. Often this means that the observation points must be high enough to allow the viewer to see over any ground-based obstructions.
Sometimes this can be used to your advantage, look at the illustration below.
The low powered handi talkie can transmit to the radio repeater at the top of the hill, then the radio repeater at the top of the hill can transmit that signal down to the 2nd user on the other side.
The two people could never talk directly to each other through the hill. You would have to have the equipment and the hilltop property ( or the owners permission) along with a power source to do this type of set-up.
Hope this helps show how VHF/ 2 meters works.
A suggestion, Study, find a group of Amateur radios operators in your area, talk to them, go take the test and get your License.
Regardless of your intentions, hobby, survival or what ever the reason, a group of radio operators can allow you the access to much more and much farther reaching equipment/systems than an individual has at there disposal......
You can learn, have security that many forms of communications are available to you, in some cases help others, and even have some fun as well.
73
Jeff
P.S.
For licensed Amateurs, there is even a guy that will
Plot your line of sight on a map for you ( as time permits)
The plots don't take into account trees, buildings, local obstructions, or geographic features that are too small to be resolved on the digital elevation maps.
