A Filtering and Electromagnetic-Transparent Antenna for Triple-Band Aperture-Shared Base Station Antenna Array

This letter presents a filtering and electromagnetic-transparent (F/ET) antenna with filtering characteristics at low-band (LB) and electromagnetic-transparent characteristics at high-band (HB) for the triple-band aperture-shared base-station antenna-array (TABA) application. The F/ET antenna consists of a dual-polarization electromagnetic-transparent main radiator and an electromagnetic-transparent parasitic cross loop (PCL) to reduce the obstructed influence of HB waves. By loading with the electromagnetic-transparent PCL, the F/ET antenna generates a radiation null at LB, realizing the filtering characteristic. Additionally, an electromagnetic-transparent coaxial line (ETCL) is proposed to suppress the HB-induced current on the LB/middle band (MB) feeding coaxial line. Then, a TABA that operates at 0.82–0.96 GHz, 1.7–2.1 GHz, and 3.4–3.8 GHz is simulated and fabricated. The attractive performance of the proposed F/ET antenna and ETCL are verified by the simulation and measurement results, demonstrating their suitability for upcoming TABA applications.