Arms Short Spiral Array Analysis Of The Method Of Moments

Phased array in circular polarization is composed with elements which are arranged in a special rule.The elements include waveguide antenna,helix bifilar antenna and cross dipole antenna, etc. Method of moments for thin wire model is used for analysis of the far field characteristic, such as axial ratio, gain and the current distribution along the line. In this paper the array arrangement witch is analysed including normal arrangement and the arrangement with rotated elements and feeding compensation. The simulation results of HFSS and FEKO have agreement with the results of this pape, it proved that method of moments for thin wire model can be used in high frequency. Using GA algorithm combined HFSS to optimize the design of balun receives a good result for the bifilar helix antenna.The major work for this paper include:1. The radiation characteristic analysis for several circularly polarized elements is done. As the requirement for high temperature up to several hundreds tolerant,this paper only introduces the analysis for bifilar helix, waveguide element and cross dipole element.2. Based on method of moment, the code for the bifilar helix array is programed. At first the single element is analysed using method of moment to get the characteristic for the far filed in free space and on the infinite ground. Then the program for the array with any feeding and any array lattice can be easily realized.The pragram is designed using multi-thread method to improve the program running speed.3. The relationship between array arrangement and far field axial ratio is given. A method based on element rotation and feeding phase compensation is proposed witch can make an optimization for the axial ration.4. Using the coupling S parameter and active element pattern simulated by HFSS, bifilar helix element’s circuit and radiation characteristic in the larger array is analysed.