Design of Low-Profile Base Station Antennas by Reducing the Height of High Band Antenna

In this work, a low-profile co-aperture base station antenna array is proposed. The antenna array consists of one low band (LB) antenna and four high band (HB) antennas, with the HB antennas positioned above the LB antenna. The LB antenna adopts a traditional frequency selective surface (FSS) loading design. To further reduce the overall height of the antenna array, a novel flexible transparent FSS film was designed, which can be directly applied to the upper surface of the HB antennas, achieving a low-profile design for the HB antennas without increasing the structural complexity. The overall height of the final antenna array is only 54 mm (0.12 λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>). Simulation results indicate that the proposed LB and HB antennas cover the frequency ranges of 0.69-0.96 GHz and 3.3-4.8 GHz, respectively. The port isolation between the LB and HB antennas exceeds 20 dB, and stable radiation patterns are observed within the operating frequency bands. The proposed antenna array offers a novel solution for the development of future 5G base station antennas.