| The antenna has become an essential component of many devices that we are exposed to in our life with the develepment of wireless communication technology in the modern society.According to the difference of the antenna radiation pattern,the antena can be divided into omnidirectional antenna and directional antenna.Meanwhile,the antenna can be divided into linear polarization,circular polarization and elliptic polarized antenna based on the antenna polarization of electromagnetic waves of the antenna,and the circularly polarized antenna and elliptically polarized have a diffrence of the left hand polarized and right hand polarized based on the propagation of electromagnetic waves.The dipole antenna is a typical omnidirectional antenna and it also is a linear polarization antenna.The archimedes spiral antenna is a typical directional antenna which is circularly polarized antenna.With the PCB technology and the improvement of processing technology and the development of printed antenna,the miniaturized antenna has become a research direction for scholars,because the direction can be good for reducing antenna volume cost savings,moreover,because it has the characteristics of light weight and good stability.The miniaturization technology of broadband antenna has many kinds,such as bending technology,stub loaded technology and change materials and so on.Through the method of load effective side based planar equiangular spiral antenna with broadband characteristics in the original paper on miniaturization.To reduce the antenna profile while maintaining the original properties of the horizontal omnidirectional circularly polarized printed dipole,by rotating the way to achieve a low profile omnidirectional circularly polarized antenna omnidirectional horizontal plane,at the same time,in order to increase its application further research and design of the ceiling antenna characteristics of an omnidirectional circularly polarized.The main work of the author is summed up in the following three points:1.A dual band miniaturized antenna is designed by the author.A planar equiangular spiral antenna radiation is the main part in the new structure of the antenna,coupled with the metal cavity and the absorbing rubber can reduce the antenna profile,the design analies the current distribution of the antenna main part of low frequency,it is useful that increasing the effective side in this position,in order to increase the effective electrical length for realizing the miniaturization of the original antenna,as the resaut,the miniaturization degree reached 15.5%.2.A low profile omnidirectional circular polarized antenna and a omnidirectional circular polarized crest antenna are designed by the author.The plane omnidirectional circularly polarized antenna is through the rotation of the printed dipole radiation as the main part.Meanwhile,the antenna couples with the microstrip transmission line to control the amplitude and phase of the implementation of the omnidirectional circularly polarized characteristics in horizontal plane,and the printing technology to achieve a good low profile.The working frequency is 3.5GHz and it can be applied to in the Wi Max system.The further research of the low profile omnidirectional circular polarization antenna combined with one points and four power dividers,which achieves the horizontal direction omni-directional circular polarization ceiling antenna in Theta=30deg direction.The working bandwidth of the ceiling antenna is 21.3% and the circular polarization bandwidth is 25.6%.3.The theisis used Time Reversal focusing technology and combined with wideband vivaldi antenna to achieve the detection of the target in space,especially for the detection and location of stealthy targets.First of all,the author used Time Reversal technique to achieve the detection of single target detection and multi objectives effectively in space.Meanwhile,the author combined with the theoretical proof to verify the feasibility of time reversal technique.Then,according to the characteristic of modern society in the stealth target and broadband narrowband absorption wave absorbing wave characteristics,the author combined with broadband the antenna emission band signal for realizing the detection and location of the stealth target by using Time Reversal technique.Finally,the author used real-time monitoring positioning to achieve the target tracking target location,and after finishing experiments to focuse on the role of time reversal technique. |
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