28 GHz waveguide antennas with fan-shaped patterns for base stations MIMO applications

Waveguide array antennas with fan-shaped radiation patterns dedicated for 28 GHz base stations MIMO applications are presented in the paper. Designed antennas operate in two orthogonal (horizontal and vertical) polarizations and provide azimuth angle coverage of 45 ^° or 90 ^° . Each antenna consists of an array of sixteen waveguide horn radiators and a corporate waveguide distribution network. Precise beam shaping to get required azimuth angle sectors is achieved with an array of printed re-directing elements realized on a single-layer Rogers RO4003C board. A narrow radiation pattern (∼4 ^° ) in elevation provides the high antenna gain of 18.8–19.3 dBi (for the 90 ^° sector) and 22.2–23.5 dBi (for the 45 ^° ) needed to ensure high communication distance. A special slow-wave corrugated structure is implemented in the designed antennas to suppress surface waves and, therefore, to increase the isolation between the orthogonally polarized antennas up to 65 dB. That allows the 2×2 MIMO transmission with polarization diversity supporting high modulation order to increase data throughput. All antennas are simulated in CST Microwave Studio, fabricated and measured. Measurement results are in good agreement with the simulations.