A survey of five generations of MIMO multiband base station antennas

As telecommunication systems evolve, there is an increasing demand for multi-band MIMO base-station antennas. Antenna arrays are generally used to support multiple frequencies with multiple ports in a compact size. However, this can result in significant degradation in scattering patterns and return loss/port isolation due to the close proximity of the radiation from the array. Various techniques have been proposed in the literature to address these issues. This paper presents an overview of the challenges faced by base station antennas (BSAs) over time and their general solutions. With the technological advancements of communication systems, accompanied by high data rates, high-frequency antenna designs and MIMO operations have been introduced at the base station level. Base station antennas encountered design challenges, including broad bandwidth, high isolation levels, stable half-power beam width, beam squint reduction, high cross polarization discrimination (XPD), gain improvement, beam steering, compact size, and cost reduction. This survey provides information on the solutions adopted by researchers over time for each design challenge, with citations. Additionally, the authors discuss techniques developed to overcome these challenges, demonstrating the evolution of BSAs from the first to the fifth generation of telecommunication systems.