Pattern-Reconfigurable Bidirectional Antenna Design Using the Characteristic Mode Analysis

This letter presents a novel patch antenna with a reconfigurable bidirectional pattern. By simply placing seven shoring pins underneath a circular patch, the proposed antenna enables the switch-overs between two orthogonal bidirectional beams and a quad-beam via controlling four p-i-n diodes. Characteristic mode analysis is applied here to provide physical insights on its working mechanism and also offer proper feeding ways for independent excitation of the desired modes. The proposed antenna was fabricated and measured. Vertically polarized bidirectional beams switchable in two orthogonal directions are generated at 3.4 GHz with peak gains of 6.8 and 7.3 dBi. As all p-i-n diodes are on, their synthetic pattern in a quad-beam can be obtained as well.