Null-Steering Antenna Design Using Phase-Shifted Characteristic Modes

A novel low-cost null-steering antenna operating at 2.45 GHz is designed by exploiting an asymmetric excitation of two characteristic modes. This compact antenna allows a null shift of the radiation pattern by changing the relative phase between the two capacitive exciters (CCEs) located above the conductive plane. As a proof of concept, a prototype of the radiator has been realized by resorting to a discrete phase shifter in order to scan the null. The measured radiation patterns prove that the proposed design strategy is reliable and applicable to other kinds of structures. The manufactured antenna is capable of steering the null within a beam of 64° centered at broadside direction (θ =0°), with depth nulls greater than 18 dB.