Study On Compact Broadband Dual-Polarized Antennas And Arrays With High Isolation

With the explosive growing number of mobile communication users and the limitation of space resources,the future wireless communication system not only needs to provide better communication quality and service,but also should possess small size to adapt to limited space environments.As a key component of wireless communication system,the performance of antenna directly affects the performance of the whole system.Therefore,the future wireless communication system has urgent demand for compact broadband dual-polarized antennas and high-density arrays with high performance.On the one hand,broadband dual-polarized antennas can use polarization diversity technology to combat multipath fading and improve communication quality,and their wide operating frequency band can also cover the multiple communication standards to save construction cost and space resources.On the other hand,large-scale antenna elements need to be integrated in limited space,which will cause strong mutual coupling to adjacent elements,reduce efficiency of the array and deteriorate the performance of MIMO system.Therefore,for the further development of wireless communication technology,not only dual-polarized antenna elements with high performance,such as broad bandwidth,high isolation levels,good cross-polarization discrimination,etc.,are required,but also mutual coupling suppression between elements with close spacing are urgently needed.Aiming at the development demand of future communication system for high performance compact broadband dual-polarization array,this paper mainly completes the following works:(1)A low-profile broadband dual-polarized metasurface antenna(MSA)is proposed.The antenna is mainly composed of a metasurface radiation patch,two pairs of orthogonal feeding strips,two orthogonal grounded microstrip balun feeding structures and an intact ground plane.The mode radiation mechanism and the formation mechanism of the dualpolarized MSA are investigated by the method of characteristic mode analysis.The proposed MSA operates at a broad bandwidth from 0.82 to 1.18 GHz,achieving a wide operating frequency band while maintaining a low profile.In addition,the proposed MSA has stable gain,good port-to-port isolation,and cross-polarization discrimination in the whole operating frequency band.(2)A composite isolator(CI)for broadband high-density dual-polarized array is proposed.The proposed CI is composed of periodic metallic strips and a metallic wall,which are etched on either side of a thin dielectric substrate placed perpendicular to the ground plane.The synergy between the strips and the metallic wall enables the proposed CI to operate over a wide frequency band range.On this basis,we have designed a twoelement broadband dual-polarized dipole array loaded with our proposed CI.The array operates at wide frequency band from 1.7 to 2.7 GHz,which covers a variety of communication standards.Without increasing the total height,the array witnesses significant improvement of isolation levels and remain stable radiation patterns over the whole the operating frequency band of 45%.The experimental results of the fabricated array are in good agreement with the simulated ones.