Generation of Radiation Null for the HMSIW Leaky-Wave Antenna

Abstract

A new design of half-mode substrate integrated waveguide leaky-wave antenna with radiation null in the radiation pattern is proposed in this letter. The radiation null is realized by controlling the leakage constant of the effective radiation sections (ERSs). By changing the vias position and extending width of substrate at the locations of the ERSs for the prescribed angle, the null region can occur in any desired direction. In this way a null region with depth 36.2 dB around θ = -96° at 9 GHz is achieved, and at the same time the main beam is almost not affected. A tapered microstrip line with shaped single-stub tuning is used for good impedance matching with the antenna. The advantage of this design is that only simple modification of structure is needed to achieve good result of radiation null.