Design Of The Multi-arm Planar Slot Spiral Antennas

With the rapid development of global satellite navigation system,it's becoming more and more popular of navigation and positioning devices in our daily life.As an integral part of the measuring antenna,it has become a hot research topic in the field.How to improve the radiation efficiency of such a measuring antenna,the characteristics of circular polarization,accuracy,and roll-off factor are the most important to improve the performance of such antennas,and that's what this article is about to study and design.Based on the application and development of the measuring antenna in the Beidou navigation system?BDS?,after studying the basic theory of micro-strip slot antenna and literature both at home and abroad,in this paper,a broadband circularly polarized micro-strip spiral antenna aperture conducted in-depth exploration.In order to ensure the antenna structure simple,the insertion loss is small,easy to process,and make it in the design band?1.2GHz-1.6GHz?within the range of S₁₁<-10dB,Gain>6dBi,AR<3dB,phase center deviation less than2mm,roll-off factor more than 9dB and other requirements,this paper proposes and designs three kinds of planar slot spiral antenna with axisymmetric structure which can be used in the Beidou System.They are mainly composed of two parts,a dielectric substrate which is etched with a plurality of slit grooves and a reflecting floor.And all of them use serial traveling wave micro-strip line feed circuit.By changing the number and shape of the spiral slot arms of the antenna,and the way of opening the periphery of the dielectric plate,to optimize the main direction gain,axial ratio and phase center stability.Firstly,this paper,based on the practical application of the ANSYS HFSS high frequency electromagnetic simulation software,by analyzing the parameters such as the dielectric substrate,reflecting floor,series feed network and the spiral slot,an eight-arm planar Archimedes slot spiral antenna is designed.The working principle is as follows:the electromagnetic wave is transmitted from the coaxial feeder to the annular series fed network on underpart of the dielectric substrate of the antenna,through the eight axial symmetry slot lines which shaped like the Archimedes spiral on the upper surface,the current flow direction is changed,with the reflection of the floor,the right circular polarization wave is realized.After observing the various parameters of the antenna simulation and the object,it is found that the axial ratio and the phase center stability has yet to be improved.Instead,the eight arms were changed to a fourteen-arm spiral antenna?the other parameters were unchanged?,and the performance was improved to a certain extent.Finally,on the basis of the two antennas,the technology of“fire wheel”was borrowed,and a new fourteen-arm tween flat aperture spiral antenna was developed.The antenna is formed by extending the shape of a slot line from the middle of the arm to the forearm,forming a trapezoid frame between adjacent arms,which can be understood that each arm is divided into two or three arms,and two intersecting metal holes are opened around the dielectric board,so as to achieve the purpose of broadening the bandwidth,and further improving the stability of the antenna phase center and the roll-off factor of the antenna.After the simulation and make the real,the indexes of the three antennas results were compared,summarized found that several antennas can be used in the field of measurement of satellite navigation,and has research value and broad market prospect.