A Pattern-Reconfigurable Filtering Patch Antenna Using Embedded Resonators and Switchable Elements

In this communication, a pattern-reconfigurable filtering patch antenna is presented which consists of a driven patch, a stacked patch, an embedded filtering feeding line, and two vertical switchable elements with gaps from the suspended patches. Compared with the conventional stacked patch antenna, the proposed antenna does not increase the volume. A novel filtering feeding network is designed which consists of a hairpin-shaped resonator and a half-wavelength coupled microstrip line. It is used to generate the radiation nulls near the lower and higher passband edges. A U-shaped slot is etched on the driven patch to generate another radiation null. Three radiation nulls are excited to realize filtering performance. Meanwhile, the radiation beam of the proposed antenna can be reconfigured by switching the function of switchable elements between a director and a reflector using p-i-n diodes. Good radiation pattern reconfigurability, filtering, and wideband performance can be achieved simultaneously. The simulated and measured results show that the radiation beam can be switched to the directions of -33 degrees, 33 degrees, and 0 degrees. The proposed antenna can maintain a wide operating bandwidth of 2.22-2.84 GHz (25%), out-of-band suppression of over 14 dB, and flat in-band gain of about 8 dBi in different states.