Design Of Substrate Integrated Waveguide Filter And Its Oscillator Application

With the development of science and technology,and in order to meet people's needs,people have began to develop a smart unmanned vehicle system.To monitor the situation outside the vehicle in real time and achieve safe driving,the unmanned vehicle needs to be equipped with a radar system with speed measurement and ranging function The Doppler radar system has received widespread attention due to its simple structure and low cost.As the signal source of the Doppler radar system,the phase noise performance of the feedback oscillator will greatly affect the ability of the entire system to receive useful signals.In order to improve the phase noise performance of the feedback oscillator,the resonant network of the feedback oscillator has been deeply studied.At present,the question of"how to achieve high quality factor of the resonant network and minimize it as much as possible"has become a research hotspot and a technical problem to be overcome.Based on such a background,this paper designs three filter resonant networks.These resonant networks are characterized by miniaturization and are used in feedback oscillators.The oscillators also exhibit good phase noise performance.Firstly,this paper reviews the transmission characteristics of Substrate Integrated Waveguide(SIW)and the basic theory and general design method of the filter.In order to achieve high quality factor and miniaturization at the same time,this paper proposes a laminated SIW based method.The design idea,using the triangular cavity as the resonance unit,successfully reduced the volume of the overall filter by half,and improved the quality factor of the circuit board layout freedom of the resonant network,and enhanced the engineering applicability.Next,the paper also analyzes the transmission characteristics of Substrate Integrated Suspension Line(SISL)and Substrate Integrated Coaxial Line(SICL).Based on SISL,this paper designs a filter with extremely high group delay and uses it as a feedback oscillator to achieve high phase noise performance(phase noise is-146.1dBc/Hz at 100kHz offset from the oscillation frequency).Then,this paper proposes a new scheme for miniaturized filter design based on SICL structure.This scheme realizes miniaturization of the filter and has a high quality factor.When used as an oscillator,it exhibits good phase noise performance(phase noise is-130.4 dBc/Hz at 100 kHz deviating from the oscillation frequency).Moreover,the filter has a simple structure and greatly simplifies the design process in engineering applications.Finally,this paper analyzes the working principle and design method of the feedback oscillator.Combined with the above research on the resonant network,this paper completes the design of the feedback oscillator.