Design Of Dual-band Dual-polarized Base Station Antennas In Mobile Communication Systems

With the rapid development and evolution of mobile communication technology,2G,3G,4G and 5G coexist in today's mobile communication systems.To satisfy the needs under current circumstances,wideband antennas and multiband antennas are quite necessary.Meanwhile,the requirements of network coverage grow various in modern mobile communication systems.For example,the application of narrow beam antennas in narrow areas contributes much in improvement of efficiency of coverage and avoiding the interference with neighboring sectors.Besides,aiming at the coverage of areas with dense population and a large amount of terminals,dual-beam or multibeam antennas help improve the volume and quality of communication.Therefore,several dual-band dual-polarized antenna are designed in this thesis base on the fundamental theory of antennas.Firstly,in order to ease the difficult of integration of antenna,a compact share-aperture dualband dual-polarized antenna is proposed in this thesis.In this design,a low-profile dualpolarized metasurface antenna is designed with characteristics modes analysis and used as the lower-band(LB)antenna.And the higher-band antenna unit is a crossed-dipole designed as a frequency selective surface(FSS)unit.The proposed dual-band antenna has bandwidth covering 3.4-3.8GHz and 4.8-5GHz,and its size is 36% smaller than ordinary dual-polarized antenna in use in this band.Secondly,we design a six-port dual-band dual-polarized narrow beam base station antenna array.In its operating bands of 690-960 MHz and 1710-2690 MHz,this antenna array achieves VSWR<1.5 and ISO>26d B.By optimizing the configuration of reflector,stable beamwidth and low backward radiation is realized.The HPBW of the antenna array in horizontal plane within the range of 33°±5°,and the front-to-back ratio is over 25 d B.Besides,the antenna achieves 2°-11° electrical down tilt in vertical plane,which make it valuable in practical use.Lastly,considering the need of integration of multibeam antenna and normal antenna,two dual-band hybrid beam antennas are designed to generate ordinary 65° beam in lower band and dual beams in higher band.Both antennas are designed with the application of frequency selective surface.One uses a V-shaped reflector to realize dual beam radiation and hybrid baffle consisting of metal and FSS to control the beamwidth of lower band antenna.The other one uses an inverted V-shaped reflector and designs the lower band antenna unit with a configuration of FSS to erase the bad effects on the radiation of higher band antenna.Both antennas operate within the frequency range of 0.69-0.96 GHz and 1.7-2.7GHz with stable radiation performance.