Design of Pattern Reconfigurable Printed Yagi-Uda Antenna

This paper presents a pattern reconfigurable Yagi-Uda antenna on an FR-4 printed circuit board (PCB) for 2.435-2.465 GHz-frequency short-range radiocommunication devices. To realize the antenna, pin diodes are attached onto the antenna's driven elements and parasitic elements. The direction of the beam is shifted by alternating the pin diodes status between ON and OFF to induce a quad-directional operation so that E-plane maximum beams are formed in the directions of 135 degrees, 45 degrees, 310 degrees and 225 degrees (i.e. regions 1, 2, 3, 4), respectively. A series of simulations are performed on four parameters: microstrip-to-CPS (coplanar stripline), inter-parasitic spacing, parasitic length, and modes of parasitic elements (i.e. director/reflector) to determine the optimal antenna design. A prototype is fabricated based on the optimal simulation results. The experiments showed very good agreement between the simulation and measured results with regard to the reflection coefficients, radiation patterns and gains for all four beams.