Design of High-Performance Antenna System for High-Speed Railways

In this paper, a systematic and efficient method is proposed to collectively synthesize the pattern for multiple antennas on highspeed railways (HSRs) based on pixel structures and N-port network, achieving an overall omnidirectional circularly polarized (OCP) pattern over a broad elevation angle. The integration of flush-mounted cavity-backed antennas not only enhances communication quality but also eliminates the undesired aerodynamic drag. Network parameters and radiating features of the N-port network based on pixel structures are firstly retained through full-wave simulations. Subsequently, without resorting to extra simulations, the configurations of multiple antennas are precisely synthesized through numerical calculations. The beam direction and beam width of each element can be automatically adjusted, promoting a seamless omnidirectional radiation feature. Following the approach, the proposed antenna thoroughly cover the 5G N41 band (2.515-2.675 GHz), delivering omnidirectional, high-gain, right-hand CP radiation throughout the entire 160 MHz band from theta = 50 degrees to 100 degrees. The averaged CP gains and ARs reach 6.09 dBi and 2.36 dB, respectively, within the target region. The antenna system was validated experimentally, with the measured results agreeing well with the simulated ones. Such radiating characteristics perfectly match the established base stations antennas.