| Ultra Wide Band(UWB)antenna technology is the key technology of UWB radar and guidance systems.Applications of UWB antennas to guided enhance resolution for radar systems and enable missiles to have strong reception and anti-interference ability,resulting in their wide utilization in military field.Therefore,development of the UWB antenna technology has important theoretical and engineering significance.Planar spiral antenna,as a form of UWB antenna,has been rapidly developed,due to its compact size,light weight,low profile.The antenna system can be greatly reduced in size,the optimal layout of the antenna system on the carrier can be realized,and the radar cross-sectional area of the system can be effectively reduced,which has a good application prospect.Planar spiral antennas are widely used not only in the military field,such as radar and guidance systems,but also in the civilian field,such as satellite communication systems.This topic of this thesis is to design an applicable planar spiral antenna.This thesis aims to design a UWB planar spiral antenna applicable to guidance systems.and the main content can be divided as follows:First,this thesis introduces the theory of UWB antennas and research status.Secondly,this thesis addresses the operating principle of planar spiral antennas,as well as modeling and analysis of planar spiral antennas.A specific planar spiral antenna simulation is carried out,specifically the calculation of the radiation pattern,beam-width,standing wave ratio,gain,and axis ratio.Thirdly,the a planar spiral antenna operating from 2.5GHz to 6GHz is improved,including the backing cavity and the dielectric lens design,to enhance the antenna performance.Three kinds of absorbing material with different thickness are filled into the antenna cavity and the relationship between the bandwidth and the gain of the antenna is studied and compared.Optimization is carried out to improve the performance of a traditional planar spiral antenna with an absorbing cavity.It is demonstrated that the bandwidth and gain of a planar spiral antenna can be taken into account at the same time.The use of the planar spiral antenna is expanded to meet the requirements for use between different systems in the future.In the case of different performance requirements of the system,some biased bandwidth and some biased gain.At this time,it can be satisfied by appropriately optimizing the thickness of the filling absorbing material,which is the significance of comparative research.In order to verify the design,the actual test results of the UWB planar spiral antenna are given.It can be seen from the test results that the electrical performance index of the UWB planar spiral antenna meets the requirements in the working frequency band,the design is successful,and the test results and simulation are also performed.The results were compared and the two were more consistent.Finally,in the face of future practical applications,the system puts higher and higher demands on the antenna power capacity,and the antenna is designed with power resistance.The traditional planar spiral antenna is usually not more than 10 W because of the influence of the balancer feeding structure,spiral line and other factors.The maximum power capacity of the antenna for CW input can reach 50 W through the pertinent design of these parts. |
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