"Novel Differential-Fed Frequency-Reconfigurable Filtering Patch Antenna for 4G/5G Systems

In this paper, a new high-gain differential-fed microstrip reconfigurable filtering antenna with high common-mode rejection is presented. A pair of probe feeding port is utilized to provide differentially exciting signals. The filtering response is achieved by introducing four symmetrical open-loop ring resonator slots on the top layer surrounding the excitation ports of the patch antenna. The resonators can produce nulls at the high edge of the passband bandwidth with high gain and wide stopband characteristics. The filtering antenna is designed, simulated and optimized using computer simulation technology (CST) software with Rogers TMM3 substrate and a relative dielectric constant of 3.45. Also, the antenna has a single layer substrate with a height of 0.035 of the free space wavelength and operating at 2.6 GHz and 3.5 GHz for 4G and 5G applications, respectively.