A Method of Generating Radiation Null for Periodic Leaky-Wave Antennas

Abstract

A systematic method for generating radiation null region in the radiation pattern of periodic leaky-wave antennas is proposed using the theory of effective radiation sections. In this method, the aperture field is expanded into spatial harmonics using the mode expansion method, and the effective radiation sections of the harmonics are studied. Based on this, the radiation null region is introduced by suppressing the radiation of the effective radiation sections corresponding to the radiating mode. The proposed method is applied to a periodic-strip leaky-wave antenna. The validity of the proposed method is verified by both simulated and experimental results, showing an obvious radiation null in the prescribed angular range. This method has the advantages of easy calculation and implementation, and has little influence on the gain and beamwidth. It is illustrated that only simple modification to the antenna structure is needed to achieve nulling.