Ultra-wideband Tightly Coupled Dipole Array And Its Low-Profile Design

Ultra-wideband(UWB)antenna arrays have drown much attention recently.Because of their advantages of safety,large bandwidth,high transmission rate and high resolution,they have been widely used in military and civilian fields such as communication,detection.However,most of the traditional UWB antenna arrays are large and expensive which limits their further developments.Tightly coupled dipole array(TCDA)as a member of UWB antenna arrays,while maintaining well performance of bandwidth and scanning angle,has smaller size and lower profile than traditional UWB antenna arrays,which exhibits a good prospect.Thus,this thesis focuses on the design of TCDA and low-profile TCDA.The main works of this thesis are summarized as follow:1.The theory of TCDA and its equivalent circuit model are studied.At the same time,a modified equivalent circuit model is proposed.In the modified model,full wave simulation results are used to improve the accuracy of the circuit parameters.An example is tested and the results show that modified model is closer to the full wave simulation results than the traditional circuit model.2.An edge-coupled TCDA is designed.In the design process,the common-mode resonance caused by feed structure is mainly studied,causes of the resonance are analyzed,and a “double dipole cell” structure as well as its balun and power divider are proposed to solve the resonance.3.A parallel-plate TCDA is designed,fabricated and tested.A parameter optimization strategy based on tuning imaginary part of input impedance is proposed.The test process and results are described in detail.4.For further low-profile design of TCDA,the artificial magnetic conductor(AMC)is applied.A complete feed structure is designed for the low-profile TCDA,the resonance problems caused by the feedings are solved as well.These works lay the foundation for further fabricating and testing.