Study On Millimeter-wave Metasurface Electromagnetic Lens Antenna

Lens antenna is widely used in millimeter-wave application as a high-gain antenna.For it is high-weight and large-size,Fresnel Zone Plate Lens is preposed,to overcome the shortages of conventional dielectric lens by reducing the thickness while keeping the phase-shifting.As an artificial dielectrics,metasurface has light weight,small thickness,and tunable constitutive coefficient.The fresnel lens based on metasurface has high-gain and low sidelobe,low-profile with reduced thickness,along with the ability of beam scanning.A realization of an electromagnetic lens antenna at 35 GHz is studied on in this thesis.The work includes:1.Study on two types of metasurface unit,a closed-loop and an open-loop metasurface unit,on their performance of transmission.And analyse the unit under an incidence wave which is oblique and in different polarization angle.Then obtain the optimum parameters with the best performance of loss and range of adjustment phase-shifting.2.While it has difficulties using method for Fresnel Zone Plate directly to design the lens,that the desgined phase-shifting of the sub-zones on the edge of lens may be out of the adjustment range of the unit,two modified methods are proposed in this thesis.Guarantee the low-loss or phase-shifting of the units in the zones in which desgined phase-shifitng is out of adjustment range.By comparing the performance of the two lens antennas in the two methods,determine the method of lens design.3.Analyse the performance of the metasurface lens antennas based on the lenses made up of the two types of unit,assembled with horn antenna and polyrod antenna.4.Experiment on the metasurface lens antenna based on the close-loop unit.The experimental results indicate that the gain is 26.4 dB,the aperture efficiency is 25.4%,and HPBW is 5.5°,which are consistent with the simulated results.