"33cm 900mhz 902-928mhz Radio Propagation"


Signal propagation on the 33 centimeter band is very dependent on the transmitting and receiving antenna's line of sight. Because of this, many wide-area coverage systems like repeaters are located on top of large hills and mountains which overlook a vast area. This ensures that the transmitting antenna is higher than terrestrial obstructions such as trees and buildings. Assuming that the transmitting antenna's wavelength, height above average terrain, and effective radiated power is equal, a transmitted signal on 33 centimeters will, generally speaking, usually travel about 3/4 of the distance that the same signal would if transmitted on the 70 centimeter band. The reader is advised to note that receiver front-end noise figure and antenna gain are the defining factors in line-of-sight signal propagation in the local area. The 33 centimeter band offers excellent building penetration characteristics since the wavelength is relatively small and can fit through windows easier than signals lower in frequency. In many areas, the 33 centimeter band also has a very low noise floor as compared to bands lower in frequency.