Research On Differential Dual-Band Dual-Polarization Antenna With Large Frequency Ratio And Low Profile Reconfigurable Metasurface Antenna

Improving communication capacity is an important research direction of mobile communication system at present.Microwave frequency band is the main communication frequency band of modern wireless communication,but the available wireless communication spectrum resources are relatively scarce,while the millimeter wave has plenty of spectrum resources,so a microwave and millimeter wave dual-frequency antenna can improve communication capacity,then the dual-polarization technology with differential feed can improve communication capacity while increasing the port to port isolation and to reduce the cross polarization.Broadband and polarization reconfigurable are also effective technologies to improve communication capacity.Metasurface antenna has the characteristics of broadband and low profile,and they is easy to realize polarization reconfigurable.However,it usually has a large size,so its miniaturization research has certain value.Orbital Angular Momentum(OAM)antennas can transmit signals in different modes at the same frequency,and the reconfiguration of OAM mode can increase the communication capacity.Radar Cross Section(RCS)is an important indicator to measure the stealth performance of an antenna.Incorporating RCS reduction technology into OAM antennas,makes it valuable in secure communication field.In this paper,the differential dual-band dual-polarization antenna with large frequency ratio and low profile reconfigurable metasurface antenna are studied.The main tasks completed in this paper are as follows:1.A differential dual-band dual-polarized microstrip cross mesh array antenna with large frequency ratio is designed.The antenna operates at a dual-band of 3GHz and 29 GHz,which is a large frequency ratio antenna with a frequency ratio of 9.67.Two groups of differential feeding ports are introduced so that the antenna can achieve a port to port isolation higher than30 d B and cross polarization below-20 d B when measured in both frequency bands.The simulation of the short side width shows that increasing the short side width can effectively improve the antenna gain in high frequency band and reduce the side lobe.2.A miniaturized low-profile tri-polarization reconfigurable broadband metasurface antenna is designed.First,a metasurface composed of miniaturized cells loaded with diagonal orthogonal capacitors is designed using the CMA method.The miniaturized cell has a 46%reduction in size compared with the traditional square cell.Then a ground four slots is placed below the metasurface,and a microstrip feed line with only two PIN diodes is placed below the ground.By controlling the state of the PIN diodes,the tri-polarization reconfigurable of lefthand circular polarization,right-hand circular polarization and linear polarization can be realized.The designed antenna has a smaller size of 0.58 ×0.58 ×0.04 and keep the wide bandwidth.The impedance bandwidths of circular polarization and linear polarization are24.6% and 21.6%,respectively,and the axial ratio bandwidths are 15%3.A low-profile metasurface antenna array with circularly polarized OAM mode reconfigurable and RCS reduction is designed.Frist,the circularly polarized metasurface antenna composed of polarization conversion units is arranged on a chessbroad to form an antenna array to achieve the overall RCS in different degrees of reduction within 4.5-7.5 GHz.Then a microstrip feed network is placed below the antenna array,and the reconfigurable OAM mode l = ±1 can be realized by controlling the state of PIN diodes.The array antenna has wide impedance bandwidths of 33% and 35.3% in both modes,respectively.