The frequency of the rf energy in the pulse radiated by a radar is referred to as the CARRIER
FREQUENCY of the radar system. The carrier frequency is often a limiting factor in the maximum range
capability of a radar system because radio frequency energy above 3,000 megahertz is rapidly attenuated
by the atmosphere. This decreases the usable range of radio-frequency energy. Therefore, as the carrier
frequency is increased, the transmitted power must also be increased to cover the same range. Long-range
coverage is more easily achieved at lower frequencies because atmospheric conditions have less effect on
low-frequency energy.