A Method to Suppress the Coupling of Dual-Frequency Antennas

5G antennas are usually integrated with the 2G/3G/4G antennas to save the tower space and cost. However, this will bring problems of mutual interference. In this letter, by setting a periodic coupling suppression structure near the radiating arms of the low-band element, the low-band element cannot perceive the energy of the high-band element, thus weakening the coupling between them. More importantly, the periodic coupling suppression structure has almost no effect on the radiation pattern of the antenna. The authors selected two different antennas for verification. The results show that the average/maximum value of the mutual isolation between the high- and low-band elements with the same polarization is increased by 12 and 17 dB with the adoption of the periodic coupling suppression structure. A robustness analysis of this decoupling method is given. The mutual isolation of different elements can keep at a high level, no matter where the low-band element is located. To sum up, the method to suppress the coupling of dual-frequency antennas has the characteristics of high integration, high space utilization, and no extra gain loss, and has a very important reference value for solving the coupling problem in 2G/3G/4G/5G array.