Shared Aperture Reflectarray For Dual-Polarization And Its Shaped-beam Method

With the rapid development of technologies in the communications field,people are increasingly demanding high-gain,multi-functional antennas in the microwave,satellite,and radar communications fields.Reflectarray Antennas,which combine the advantages of a reflector antenna and a two-dimensional array antenna,are receiving increasing attention.Based on the Phase Shifting Surface(PSS)concept,the planar microstrip array antenna loaded with microstrip patch units gradually becomes a new research hotspot for its simple structure,low profile,low processing cost,and flexible beam design.The content of this article is based on the design flow of a reflective array antenna.A common-aperture dual-polarized reflective array antenna is designed and the beamforming function is implemented.A global optimization algorithm is introduced to optimize the phase of the array.The specific work content is as follows:1.Shared-Aperture Reflectarray for Dual-PolarizationThe broadband single-layer reflective element designed in this paper shows excellent polarization isolation,so based on this,we design a dual-polarization reflectarray.It has two modes of operation,corresponding to two orthogonal polarized incident excitations.In the end,the same antenna array can generate different reflected beams under different polarization modes.The azimuth angles of reflected beams generated in the two orthogonal polarization modes are(15°,0°),(-15°,0°),respectively.The reflective array can work stably in the frequency range of 11.3-13.1 GHz.For both polarization modes,the side lobes of the reflected beam can be kept below-15 dB.2.Design of Dual-beam Reflectarray And Array Phase Optimization Based on PSO AlgorithmIn this paper,a dual-beam reflectarray is designed,which consists of an 18?18 array with a working frequency of 12.2GHz.For a polarization mode,two target beams with azimuth angles of(15°,45°),(15°,-45°)can be generated.This work uses the geometric partition method and phase synthesis optimization to implement a method for designing an arbitrary multi-beam reflectarray.First,two 9?18 pencil beam reflection arrays are spliced to obtain a preliminary unit phase distribution;Particle Swarm Optimization(PSO)is used to optimize the phase of the entire array after splicing,which greatly improves the performance of the overall reflective array.Using this kind of local array splicing together with the design idea of the global optimization algorithm,an arbitrary shape multi-beam reflective array design can be realized.3.Shared-Aperture Shaped Coverage reflectarray for Dual PolarizationThis work applies the PSO algorithm directly to the beamforming design of the reflectarray.Combined with the unit design of the polarized beam splitter,the design of a more complex co-calibrating polarization shaped-coverage array is realized.Based on the dual-polarization reflectarray unit,different target coverage are set for the two polarization modes.The phase optimization of the array unit in each polarization mode through the PSO algorithm ends in the expected results.The two working states of the reflectarray are: square cosecant beam for TE polarization and dual beams for TM polarization.The central frequency of the reflectarray is 12.2 GHz,and the array consists of 18?18 units.