Suppression of Cross-Band Coupling Interference in Tri-Band Shared-Aperture Base Station Antenna

A triband shared aperture (TBSA) antenna is proposed to meet the new requirements of base station antennas for multiband antennas fusion. The proposed TBSA (P-TBSA) antenna is composed of a lower band (LB, 790–960 MHz) antenna, two columns of middle band (MB, 1710–2170 MHz) subarrays, and a
$4\times 8$
array antenna operating at N78 band (higher band (HB): 3.4–3.6 GHz). The LB antenna is located in the center of a shared reflector. The MB subarrays are located around the LB antenna with a side-by-side scheme. The HB array antenna is located below the MB and LB antennas for multi-input–multioutput (MIMO) application. The cross-band coupling interference existing in the P-TBSA antenna can be divided into scattering interference and common-mode interference, which will seriously deteriorate its performance. To suppress the scattering interference, an LB crossed dipole antenna with low radar cross Section (RCS) at both MB and HB and an MB crossed dipole antenna with low RCS at HB are designed. In addition, the method of “path extension” is used to suppress the common-mode interference. By taking the above measures, the distorted radiation pattern of the P-TBSA antenna is significantly recovered.