| With the change rapidly of electronic communication technology and circuit integration technology,wireless transmitting and receiving equipment has more and more strict requirements on the performance and size of the antenna.The key point is to realize all kinds of microwave active and passive devices including the antenna to work in the ultra-wide working band,and the structure tends to be miniaturized.So how to achieve the balance between antenna performance and size to design a compact ultrawideband antenna is one of the key issues in the research of microwave RF devices and antenna design technology.Vivaldi antenna is a kind of tapered slot antenna,belonging to the ultra-wideband antenna.It has the advantages of wide band,stable gain,symmetrical pattern,simple structure,easy integration and low cost.It is widely used in radar system,electronic warfare and wireless communication.In this paper,Vivaldi antenna is selected as the research object.Based on the dual requirements of Ultra-wideband and miniaturization,the main research work includes:A new design method of superimposed Vivaldi antenna is proposed and improved to achieve better performance.1.The balun structure is studied and designed,and the ultra-wideband microstrip wire-trough wire feed balun is designed.From the perspective of design,Vivaldi antenna mainly consists of two parts:radiation structure and feed structure.The radiation structure is the radiation arm of the antenna,while the feed structure is the balance and unbalance converter-baron.There are various types of feed balun.This paper mainly studies and analyzes the microstrip wire-slot converter,and designs the ultra-wideband microstrip wire-slot feed balun structure in the working bandwidth of 400MHz～6GHz.2.The radiation structure is studied and designed,and a design method of superimposed Vivaldi antenna is proposed.Based on the design principle that impedance matching and radiation performance of Vivaldi antenna can be effectively improved by changing the current distribution on the edge of the radiation arm by changing the geometry of the radiation arm,a superimposed Vivaldi antenna composed of two segments of Vivaldi is proposed.This structure can significantly improve the impedance characteristics of low frequency band.And there is a good radiation direction map.Secondly,various parameters are analyzed and compared,and the influence of each parameter on antenna performance is summarized3.Research and analysis of antenna performance improvement methods.At present,many methods have been proposed to improve the performance of Vivaldi antenna.In this paper,the edge periodic structure,truncated slot structure,loaded resistance element and dual polarization structure are studied and analyzed to explore the influence of different methods on the impedance characteristics and radiation characteristics of Vivaldi antenna.4.Experimental test and comparison of superimposed Vivaldi antenna.Combined with the method to improve the performance of the antenna,a 15-octave superimposed Vivaldi antenna with a working bandwidth of 400MHz～6GHz is designed.The effectiveness and feasibility of the design method are verified by testing in the microwave darkroom. |
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