Design of symmetric beam pattern reconfigurable antenna

A radiation pattern-reconfigurable antenna is designed to operate over DCS 1800 and PCS 1900 bands. The proposed antenna is symmetric with respect to the vertical centre line and has a pair of pin diodes for switching. The electrical shape of the antenna consists of a monopole-loaded loop and an open wire, which serves as a director. Depending on the switching state, the antenna can select between two beam directions with essentially no input impedance variation. The return losses and radiation patterns for two bias conditions are measured and compared with simulated results. The measured results indicate that the antenna has high front-to-back ratios for both bias conditions, representing clear pattern reconfigurability.