Study On Measurement Techniques Of Optically Controlled Phased Array Antenna For Mobile Communications

Optically controlled phased array antenna(OCPAA)system based on microwave phonics and microstrip antenna has a wide development prospect and values in wireless mobile communications,due to its characteristics of low loss,wide bandwidth,compactness in size,flexibility and electromagnetic stability.In this paper,the measurement system and techniques of OCPAA have been discussed theoretically and experimentally,from the view of industrialization of OCPAA system for mobile communication.Firstly,the measurement plan of OCPAA system is proposed and discussed.The antenna performance parameters of OCPAA is defined,and the antenna structure and material properties on antenna performance have been analyzed by means of full wave simulation.A four-element microstrip array antenna is designed and optimized numerically according to the predefined parameters.It is then fabricated and measured with bandwidth and gain,which are in good agreement with the performance parameters.Secondly,based on a transformation-optics designed impedance tunable reflectionless waveguide,a metamaterial TM-pass polarizer comprising polymer and graphite is proposed to improve the cross polarization in OCPAA measurement system.In order to fulfill the design,the structure of practical metamaterial is realized through discretizing relative permittivity for stacked panels and effective medium approximations.Influences of panel parameters on transmittance of metamaterial has been simulated.A metamaterial sample is fabricated by means of 3D-printed polylactic acid panels that are filled with pressed graphite powder via a novel graphite tape mask filling(GTMF)method,which is able to build metamaterial with high permittivity variance.Next,a composite pyramidal absorber with frequency selective surface(FSS)of dipole cross and square ring in both single layer and dual-layer configuration is proposed and analyzed to improve the absorber reflectivity below.Sample absorbers with configurable bases of different FSS patterns are fabricated via a novel graphite screen printing method(GSPM)by printing the graphite patterns onto paper sheets attached to the absorber bases.Measured results show that the absorbers fabricated by the GSPM have improved the reflectivity for both single-layer and dual-layer configurations.Meanwhile,a compact multi-purpose shielding room with novel movable absorber screens is designed and established using the proposed absorbers,showing a shielding efficiency of up to 60 d B.We have also proposed the shielding and absorber plans for a far-field anechoic chambers and verified its performance with a shielding efficiency of up to 90 dB.Lastly,test procedure for measurement of OCPAA system for mobile communication is proposed,detailing the measurement technique and instrumentation for measuring OCPAA mutual coupling,directivity,gain,phase,polarizer etc.Both the array antenna alone and the OCPAA system have been measured accordingly.Measured results show that the array antenna meets the predefined antenna requirements on mutual coupling,bandwidth,beamwidth and gain,while source of errors of the OCPAA measurement system is also discussed.