Low sidelobe reflector antenna design for communications

Abstract

The current antenna used in the Marine Radio AN/MRC-142 is a focal point fed reflector with a first sidelobe of -10 dB. A new antenna design is required with a sidelobe reduction of another 10 dB, and a minimum impact on the system upgrade cost. An improved feed consisting of a fed dipole and disk in the vicinity of a parasitic ring was designed for use with the current reflector. The disk acts as a ground plane for the dipole, with the ring narrowing the beamwidth. resulting in a stronger edge taper on the reflector. An existing computer code based on the method of moments was used to compute the gain and the radiation pattern. Circular parabolic reflectors of 36 inches and 48 inches were analyzed. The results show that the 36 inch reflector cannot satisfy the conditions over the entire frequency band (1350 to 1850 MHz) simultaneously. The 48 inch reflector came very close to satisfying all the conditions, although the sidelobe level is off by approximately 2 dB at wide angles in the H-plane