A Pattern-Reversal Wideband Antenna Integrating Metal Rings, Diodes-Loaded Stubs and Defective Ground

The pattern reconfigurable antenna provides a new implementation scheme for expanding application in modern wireless communications. In this paper, a pattern-reversal wideband microstrip antenna is proposed. This antenna is composed of a radiation patch with attached rectangular metal rings connected by a microstrip line on the upper layer and a four-defects ground plane connecting two PINdiodes- loaded L-shaped stubs on the bottom layer. In view of the Yagi-antenna feature of metal rings and L-shaped stubs, the ON-OFF of diodes controls directly the radiation direction of antenna. Under the joint action of multiple resonances of rings, slots and stubs, the bandwidth of antenna is surged so as to develop evident wideband radiation. Finally, the measured impedance bandwidth of −10 dB is about 20.1% from 4.54 to 5.55 GHz. The average gain of the antenna with the size of $0.75 \lambda_{0} \times 0.75 \lambda_{0}$ reaches 4.92 dBi. With the diodes dependence, the pattern can really deflect in opposite direction. The designed antenna has much advantages, such as low cost, wider band, compact and simple structure along with explicit application scenarios.