DefinePK

Abstract

Much energy is saved in the daily operation of FM broadcast stations if the transmitting antenna system employed transmits RF signal only in directions where the signal is wanted. Most FM broadcasters employ antenna systems that radiate equally in all directions or having an omnidirectional pattern on the horizontal plane. In most cities where broadcast stations operate, the target population are located only in some directions from the antenna location and definitely not around it. The use of correct radiation patterns in FM broadcasting is very important to assure that every RF energy emitted by the transmitter is received only within the target areas and not to be wasted in directions where the signal is not needed. This paper presents a method of producing directional patterns that are suitable for FM broadcast applications with simple implementation. These patterns are shaped by varying the physical distance and the phase relationship of two basic antennas called bays in uniform linear array. The bay used in the array is the shunt-fed, slanted dipole commonly used in FM broadcasting. Computer simulations show that the patterns presented in this paper have sufficient gains in certain directions, greater beamwidth and sidelobe-free. Though only two control factors are used in shaping the radiation pattern of the array, several patterns can still be produced that find practical applications in FM broadcasting.