Research On The Broadband Technology Of The Microstrip Antennas

In recent years,antennas that are widely used in communications, radio,radar,guidance systems as crucial components change a lot in its function,design and process of manufacturing.Microstrip antennas are very promising due to their attractive merits,such as light weight,capability of conformality,ease to integrate and match.The application of microstrip antenna will not be replaced in the future, especially in the mobile communications and personal communications systems. However,the bandwidth of conventional single layer microstrip antenna is only about 0.7%to 7%,which prevents the microstrip antenna from wide application.Many researchers put their effort in getting wide bandwidth of microstrip antenna,and have improved the bandwidths to 13%,16%,25%and even 40%(VSWR<2)by using different methods.This thesis intends to do some works in bandwidth improvement of the microstrip antenna.Good performance can be achieved by changing the shape of radiation patch and the feeding structure.The main works and the creative parts of this thesis can be summarized as follows:1.The broadband technology of microstrip antennas is summarized.The radiation characteristics,the classification,and the feeding model of the microstrip antennas are discussed.The applications and development trends of the microstrip antenna are introduced.2.The hot topics of the microstrip antennas,such as the wideband enhancement technology,the miniaturization technology,and the multi-band technology,are discussed in theory and practice.In order to fit the scope of this thesis,the broadband technology of microstrip antenna is introduced especially.3.A loaded rectangular patch microstrip antenna is proposed.By the use of loading technique,the relative bandwidth of the proposed antenna can reach about three times that of the antenna without loading.The proposed antenna is fabricated and measured,and the experimental results are in well agreement with the simulated results.4.The circular patch antenna fed with capacitor compensation probe is studied. With carefully design of the feeding structure,the relative bandwidth of this kind of antenna can reach 13.8%.