Development Of Sub-nanosecond Pulse Source Based On Marx Circuit

With the special advantages of time-domain antennas in the fields of Ultra-wideband(UWB)radar,impulse radar,medical imaging and so on,UWB radio technology has become a hot topic for scholars.With the rapid development of wireless communication,in order to reduce the interference of various new multi narrow band communication systems on UWB signal,we need to design UWB antenna deeply.In addition,for the special needs of some applications,the requirements of higher miniaturization and integration requirements of time domain antenna and UWB antenna are also put on the agenda.Firstly,this thesis explains the research background and significance of UWB technology.In this thesis,the application of UWB technology in radar,communication and other fields is introduced.Combined with the correlation between the transient pulse signal and the spectrum width in UWB technology,the typical UWB antenna commonly used in radiating time-domain signals is briefly introduced and analyzed.On this basis,the research situation of UWB antenna is summarized.Among them,how to design the time domain antenna and UWB antenna with more high power and miniaturization is the top priority of today's research.Secondly,the basic performance parameters of the antenna and the time domain antenna are briefly introduced,and the similarities and differences between the time domain antenna and the narrow-band antenna are briefly described.The frequency and time domain characteristics of several transient pulse signals commonly used in UWB technology are analyzed.According to the generation mechanism of time domain pulse signals,the principle and working process of generating pulse of Marx circuit and Blumlein line based on avalanche tube are briefly described.Then according to the requirements of the project,the Blumlein wire and the Vivaldi slot antenna are designed respectively.Three different grooving processes are used for the Vivaldi slot antenna.The low frequency bandwidth of the antenna is extended effectively,and the radiation performance of the antenna is increased.PSPICE and CST were used to simulate the Blumlein line from the point of view of road simulation and field simulation respectively,to explore the influence of different factors on its output pulse.The zero-order Gaussian signal of 1.5ns is obtained from the actual measurement.After testing the processed object,it shows that it can achieve the pulse output with 78.6% efficiency.By changing the length of the microstrip and the value of the series inductance at the input end of the Blumlein line,the output signal like the first order Gaussian signal is obtained.The basic size of the contral-heel Vivaldi antenna is300×290 ×2mm3,and the standing wave ratio in the 550 MHz to 5GHz frequency band meets the requirement of less than 2.Among the three grooving methods,the symmetrical circular arc grooving on both sides of the antenna has the best effect.Before and after grooving,the low frequency of the antenna decreases from 550 MHz to420MHz,which effectively improves the low-frequency radiation characteristics.The gain is increased from-0.92 d B to 5.16 d B after grooving in the 400 MHz band.The improvement of low frequency radiation performance not only makes the waveform fidelity higher,but also reduces the trailing of the signal.Finally,it is integrated with Blumlein line.The modeling and simulation of the integrated antenna in CST show that the test results are in line with expectations.