Design of a Directly-Fed Pattern Reconfigurable Patch Antenna and Its Array Performance

A directly-fed pattern reconfigurable patch antenna without extra feeding networks is presented in this paper with a straightforward design method and the discussion on its array performance.
$\mathrm{T}\mathrm{M}_{01}$
and TM
02
modes of a rectangular patch are employed to realize pattern reconfigurability. Four shorting pins underneath the patch and two high-impedance open-ended stubs loaded on the radiating edges are adopted for the frequency overlap of the two working modes. Additional center-carved slots or center-loaded stubs are proposed as a simple impedance-matching mechanism without feeding networks. The working principle is investigated by a transmission-line circuit model. Simulation results show that at 2.45 GHz, the radiation pattern of the proposed antenna can be switched between a single beam and dual beams with maximum realized gains of 9.6 dBi and 5.6 dBi, respectively. Moreover, a 1×4 array is designed using the proposed antenna to demonstrate its array performance.