A Pattern Diversity Microstrip Antenna with Switchable Sum and Difference Beams in $E$ - and $H$ -plane

A design of a planar microstrip patch antenna with pattern diversity along both E- and H-plane is presented in this paper. At first, a microstrip design with switchable E-plane sum and difference patterns is presented with its operation based on selective excitation of two fundamental modes. On this basis, the design is extended to a double-element configuration along the H-plane. This arrangement enables pattern diversity along both E- and H-plane. For the single element antenna, a configuration of ten PIN diodes and a decoupling shorting via are utilized to switch between the TM01 and TM02 modes without relying on a feeding network. For the double-element antenna, a coupler acts as a feeding network and allows to generate the sum and difference patterns along the H-plane.