UHF versus VHF
The most common two-way radio systems operate in the VHF and UHF parts of the radio spectrum. Because this part of the spectrum is heavily used for broadcasting and multiple competing uses, spectrum management has become an important activity of governments to regulate radio users in the interests of efficient and non-interfering use of radio. Both bands are widely applied for different users.
UHF has a shorter wavelength which makes it easier for the signal to find its way through rugged terrain or the inside of a building. The longer wavelength of VHF means it can transmit further under ideal conditions. For most applications, lower radio frequencies are better for longer range. A broadcasting TV station illustrates this. A typical VHF TV station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF TV station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.
If an application requires working mostly outdoors, a VHF radio is probably the best choice, especially if a base station radio indoors is used and an external antenna is added. The higher the antenna is placed, the further the radio can transmit and receive. One exception to using a VHF radio outdoors is if it is used it in a heavily wooded or rugged area. Under these conditions a UHF radio may be able to transmit better though the terrain (unless the VHF antenna is raised above the terrain).
If the radios are used mainly inside buildings, then UHF (or even 800 or 900 MHz) is likely the best solution since its shorter wavelength travels through the building better. There are also repeaters that can be installed that relay a UHF signal to increase the communication distance.
There are more available channels with UHF, so in more populated areas UHF may be less likely to have interference from other systems. Since the range of UHF is also not as far as VHF under most conditions, there is less chance of distant radios interfering with the signal.