Using FDTD Method To Analyze A Single Ridged Waveguide Antenna For Near Field Measure And The Optimization Reaserch Of MEMS Phase Shifter

The paper analyzed an S-band single ridged waveguide antenna used for near field measure by FDTD method and microwave transmition line theory. Reference[1] has used the FDTD to solve some ridged waveguide and waveguide antenna to obtain the inside field. The feature of the paper is to analyze the antenna's near field in the rubber absorbing materials. For radiating from the margin, the microwave antenna can not work well to fufill the high resolution requirements. And waveguide has a too large structure to satisfy the requirement when working at a low frequency band. But ridged waveguide antenna which is small in volume when working at a low frequency band can obtain a high resolution and is suitable in the rubber material measure.One of the features of the paper is that some improvements of FDTD are presented. A pulse hard source has been adjusted to allow the reflection wave pass by the source without retroreflection. And the calculation area is changeable at the different time step, so only those area with wave propagation have been calculated. As the results, the total calculation time can be reduced.Another important part of this paper is optimal design of a micro-electromechanical systems (MEMS) phased shifter using Genetic Algorithms (GAs). According to the characters of MEMS structure, some improvements of GAs are discussed and a varying population hybrid Genetic Algorithms (VPSG_GM) is presented. In this approach, the population of individuals are adjusted by the degree of evalution. The gradient method is combined to the apprioach in order to enchance the efficiency of the algorithms in local area. After optimization, a high performance Millimeterwave MEMS phase shifter is obtained.