A Shared-Aperture Compact Quad-Band Linearly-Polarized Base Station Antenna

In this paper, we propose a mixed-decoupled and compact quad-band linearly-polarized base station antenna. The design integrates two lower-band (LB) antennas operating in the $687-926 \mathrm{MHz}$ and $1564-2644 \mathrm{MHz}$ bands, and two upper-band (UB) antennas covering the 3304-3717 MHz and 4650-5017 MHz bands, all with excellent isolation. To minimize mutual coupling, we employ L-shaped parasitic branches, an array-antenna decoupling surface (ADS), and a frequency selective surface (FSS). This innovative approach addresses the challenges of integrating multiple frequency bands into a single compact system, providing a practical solution for modern base station applications.