Research On On-Line Measurement Method Of S-Band HPM

High-power microwave measurement plays an important role in the microwave field as a monitoring and evaluation method of microwave system.According to different principles,high-power microwave measurement methods are divided into three categories: absorption microwave measurement,radiation microwave measurement,coupled microwave measurement(online measurement).Compared with other measurement methods,coupled microwave measurement uses a coupling device to separate a small part of high-power microwave for measurement.High-power microwave can be obtained by measuring and calculating small-power microwave.It has the advantages of dynamic measurement,real-time monitoring of the operation of high-power microwave source,and being able to be competent for the measurement of a variety of test scenarios.It is widely used in online measurement of high-power microwave.At present,the practical high-power microwave on-line measurement device is developing towards the direction of compact structure,high power capacity,broadband,long service life and so on.Traditional S-band rectangular waveguide on-line measurement devices,such as waveguide directional coupler and coaxial electric probe coupler,generally have the disadvantages of large structure and low power capacity.In order to overcome these shortcomings,a new S-band high power microwave on-line measurement device based on choke coupling structure is proposed in this thesis.The improved choke coupling structure is applied to high power microwave on-line measurement,The choke coupling structure is used to weakly couple the high-power microwave on the main line,and the coaxial probe is combined at the end to sample and measure the microwave signal,which effectively avoids the local field enhancement at the probe or opening,so as to improve the power capacity and meet the requirements of GW high-power microwave measurement.At the same time,the high-power microwave on-line measurement device has compact structure,convenient use,good sealing performance,and can be competent for the on-line measurement of high-power microwave in different scenarios,which has a great application prospect.The main work and research content of this thesis:1)In order to overcome the shortcomings of the traditional on-line measurement device,a new S-band high-power microwave on-line measurement device based on choke coupling structure is proposed for the actual high-power microwave test scenario.The basic principle of choke coupling structure and related theories are described,and the feasibility of applying choke coupling structure to high-power microwave on-line measurement is analyzed.2)According to the basic structure of choke coupling structure,a variety of model schemes are proposed,and the performance differences of different model schemes are compared through CST simulation analysis.The reference model of S-band(2.5GHz～3.5 GHz)high power microwave online measurement device is established,and based on the reference model,a S-band high power microwave online measurement device based on choke coupling structure is designed.The simulation results show that the power capacity of the online measurement device designed in this thesis is 3.54 GW,which has the advantages of compact structure,high power capacity,convenient use and so on.3)According to the simulation model and the actual test scenario,a set of practical and effective processing scheme is proposed for the processing problems.The Solid Works processing model is designed by using the idea of block assembly and the physical processing is carried out.The physical size is 200 mm×200 mm×200 mm,with good compactness.The coupling degree at the center frequency of 2.9 GHz is 49.52 d B.The test results are in good agreement with the simulation results.4)The high-power microwave experimental research is carried out on the designed S-band high-power online measurement device in the actual test scene.The high-power microwave experimental platform built by the teaching and research office is introduced.The methods and basic principles used in the experimental testing process are described.On this basis,the experimental results of the waveform,frequency,pulse width and power of the high-power microwave signal are given,The relative error between the on-line measurement results and the radiation field measurement results is less than 5%,and then the reasons for the differences between them are analyzed.The feasibility of applying choke coupling structure to high-power microwave on-line measurement is verified by experiments,and the performance of the on-line measurement device is tested.The experimental results show that its air tightness,power capacity,measurement accuracy and other performance indicators meet the expected design requirements.5)On the premise of ensuring compact structure and high power capacity performance index,the choke coupling structure is improved.The double ridge waveguide is applied to the choke slot at the end of the online measurement device to improve the coupling flatness and working bandwidth of the device,and its relative bandwidth is increased from 9.86% to 18.31%.Finally,the machining model was optimized and improved.Under the condition of ensuring the feasibility of actual assembly,the longitudinal dimension of the online measuring device was compressed.The optimized model size was 93 mm×200 mm×200 mm,more compact.