Compact Pattern Reconfigurable DR Antenna for Smart IoT Applications

This paper presents a pattern reconfigurable, compact dielectric resonator (DR) antenna based on a biased feeding approach. In a sandwich-like structure, the DR is divided into two parts with a cross-shaped metallic strip in the center. The cross-shaped strip is connected to a copper probe running through the bottom half of the DR, forming a top capacitively loaded monopole structure. A parallel capacitive effect is generated between the strip and the ground, thus producing a good vertical polarization. To obtain multiple switchable beams, the cross-shaped strip is cut and the four branches are connected with PIN diodes. By controlling the working states of the diodes, a total of eight directional beams and one omnidirectional beam can be obtained. The measured overlapping -10 dB impedance bandwidth is 2.35-2.8 GHz (17.5 %), with an efficiency higher than 90 % on the operating band. The antenna well suits miniaturized 2.4 GHz WIFI band and smart IoT applications.