Wideband Dual-Polarized Antennas for Base Stations (Invited talk)

Abstract

The mobile communication systems have evolved rapidly in recent decades, from the 1st generation (1G) in the 1980s to the 2nd generation (2G) in the 1990s, 3G in the 2000s and 4G in 2010s. We are now in the transition period from 4G to 5G, and there are already lots of research activities investigating the 6G technologies. A variety of frequency bands have been employed in mobile communications. Figure 1 illustrates typical frequency bands of 2/3/4/5G mobile communication base station. The 2/3/4G systems occupy a wide frequency range including 698 to 960 MHz and 1710 to 2690 MHz, while 5G employs several different frequency bands such as 3.3-3.6 GHz, 4.8 - 5.0 GHz, 37 -43.5 GHz, etc. Hence the co-existence of 2/3/4/5G becomes a hot topic. In particular, it is important to investigate the development of base-station antennas which can have a compact size and can achieve a very wideband impedance matching performance for covering the frequency bands of 2/3/4G. The antenna also needs to achieve dual polarization with high isolation between two input ports, high polarization purity, stable radiation patterns and constant beamwidth across the frequency range. In addition, the antenna needs to be immune to the inferences from radio signals of 5G systems [1]–[2]. This invited talk has two parts. First, a review of recent development in wideband dual-polarized antennas for base stations will be provided, and different antenna technologies will be discussed. Then, three examples of wideband dual-polarized antennas for base station applications, recently developed at the University of Kent, UK, will be presented. These include a wideband dual-polarized antenna which achieves a compact size by using a shared dipole approach, a compact-size highly integrated shared-dipole antenna with wideband dual polarizations, and a compact dual-polarized antenna with the configuration of the equivalent electric and magnetic dipoles and using the parasitic strips and shorting sheet to realize wideband harmonic suppression. These three antennas are verified by both the simulated and measured results, including the S-parameters and radiation patterns. Good agreements are achieved to show that these antennas can be the good candidates for the base station applications. Figure 2 shows one of the wideband dual-polarized antennas and its radiation pattern. During the talk, the designs of these three antennas and their simulation and measurement results will be discussed. Finally, a discussion of future challenges will be given at the end.