Review on 5G Small Cell Base Station Antennas: Design Challenges and Technologies

The demand for high-quality network services has increased due to the widespread use of wireless devices and modern technologies. To address the growing demand, 5G technology is being implemented at a larger scale. Small-cell Base Station (SBS) antennas are crucial for exploring the full potential of 5G networks by expanding the network in urban areas, densely populated regions, indoor environments, and low-coverage zones. This paper analyses the literature on the 5G sub-6 GHz and Millimeter wave SBS antennas, including their state-of-the-art designs and encompassing several parameters like bandwidth, gain, radiation pattern, and polarization. The integration of advanced technologies and designs, such as reconfigurable antennas, metamaterials, beam forming, phased array and massive MIMO has been given special consideration due to its importance in SBS antenna. While traditional base stations have been widely studied and implemented with multiple antenna techniques, the use of these techniques in SBSs is still developing. As networks become more complex and 5G systems require more network coverage, implementing several antenna designs in SBSs presents unique challenges related to performance and compactness. This paper discusses 5G SBS antenna designs that have been proposed recently and studies their characteristics with the parameters that enhance the performance. In addition, comparison tables analyzing the antenna designs are given to comprehend the nuances of design and implementation.