A Novel Null Scanning Antenna Using Even and Odd Modes of a Shorted Patch

A novel null scanning patch antenna operating at 2.4 GHz is presented. Unlike the existing reconfigurable techniques, the even and odd modes of a shorted patch are adopted to first achieve a broadside pattern and pattern null on broadside. Continuous null scanning is achieved by combining these two modes with different exciting powers. The mechanism of null scanning is discussed from both theoretical analysis and simulated/measured results. A rat-race switching network is used to excite the two modes and simultaneously obtain high port isolation. A prototype is fabricated and tested. The measured results verified the null scanning capability of the proposed design.