Design And Implementation Of The Air-Fed Transmitarray

The transmitarray is a high-gain antenna with wide application foreground in the field of planar air feed array antenna.It combines the advantages of the traditional lens antenna with the antenna array antenna.Its structure can be much simple than the traditional lens antenna surface structure,and it has the inherent advantages of traditional air-fed antenna: simple and light.The machining errors of the surface would not affect the performance of the transmitarray.It can realize polarization conversion and beam forming at the same time.A main design method of thetransmitarray is to use multilayer frequency selective sureface as the unit of the antenna array.This paper aims at analyzing the design method of transmitarray unit,phase compensation principle and general design principle of antenna array,and simplifying the complex structure of the multi-layer transmission frequency selective surface array unit,and reducing the higher defect of the longitudinal profile.The main contributions of the paper are shown as follows:The first part of this paper mainly analyzes the transmission type unit design method,traditional multiple frequency selective surface unitsusually have of complex structureand high empty feed array longitudinal profile.In this paper,a single layer frequency selective surface unit is presented and analyzed,which is used in the beam separation transmitarray antenna design.Furthermore,two layers of single frequency selective surface unit combined into a double layer frequency selective surface unit.The double layer frequency selective surface unit in the meet the requirement of transmission performance and the two orthogonal polarization direction transmitted wave phase by 180 degreesat the same time.It is used in the beam focusing transmitarray antenna design.The second part of this paper mainly analyzes the beam focusing transmitarray antenna.The single layer frequency selective surfaces are rotated by phase modulation technology in the opposite directions to made up of two single layer phase transformation arrays.Then the double layer frequency selective surface unitsare rotatedby phase modulation technology to made up of a double layer beam focusing transmitarray antenna.The antenna can work under two different circular polarized incident wave modes: left-handed circular polarization,the right-handed circular polarization at the same time.The function of transmitarrayantenna is to complete polarization transformation and beam focusingat the same time.After finishing the antenna design,the function of the transmitarrayis validated through processing and tests.The third part of this paper the main focused on the research of the beam separation transmitarray antenna.The single layer frequency selective surface units are rotated by phase modulation technology to made up of a single layer beam separation transmitarray antenna.The antenna can work under three different incident wave mode: linear polarization,left-handed circular polarization,the right-handed circular polarization at the same time.The function of transmitarray antenna is to complete polarization transformation and set beam separation direction at the same time.After finishing the antenna design,the function of the transmitarray is validated through processing and tests.