Tunable Monopole Antenna in the Sub-6 GHz Spectrum for Picocell Base Stations

A tunable monopole antenna in the European Union (EU) norms for the Sub-6 GHz band in picocell base stations application is presented in this paper. The antenna has a simple design with a bandpass filter incorporated in its ground plane. The frequency tunability capability of the antenna is achieved by varying varactor diodes capacitance, which leads to changing the effective length of the bandpass filter slots, as a result the operating frequency continuously tuned from 3.4 to 3.8 GHz. The designed antenna is modeled in CST, then verified using HFSS and ADS. The simulated antenna performance is analyzed in detail including the return loss, radiation patterns, and gain. The obtained results show that the developed antenna is very suitable for picocell base stations, especially for the 5G/Sub-6 GHz band.