Research On Failure Mechanism Of Amplitude Uniformity In Uniform Microwave Field

The uniform microwave field is a special spatial electromagnetic field,which requires equal distribution of field intensity in the predetermined area.It has important applications in material drying,microwave hyperthermia,electromagnetic sensitivity testing and other fields.The key to generate uniform microwave field is how to control the electromagnetic field in space.At present,the control theories and methods of electromagnetic wave propagation and spatial electromagnetic field distribution are used to synthesize uniform microwave fields.There is a general problem of inconsistency of field amplitude.It often needs a lot of optimization calculation to improve the uniformity of field distribution,which results in high computational complexity and poor flexibility of generating uniform microwave field.So that restricts the practical application of uniform microwave field.Therefore,it is of great significance and value to study the failure mechanism of uniform microwave field amplitude consistency.In this thesis,a method of generating uniform microwave field based on time reversal arrival field(TRAF)is proposed,and one-dimensional linear uniform microwave field is simulated and realized.Combined with the theory of time reversal arrival field,the failure mechanism of amplitude uniformity in uniform microwave fields is emphatically analyzed,and study the methods of improving the uniform microwave field amplitude consistency for support of the research,design and physical generation of uniform microwave fields.The main contents are as follows:First,by combining the time reversal focusing theory and the arrival field theory,a method named time reversal arriving field(TRAF)is proposed for generating uniform microwave fields.The mathematical analysis model of one-dimensional linear uniform microwave field is established,and the numerical simulation is carried out by using MATLAB software.Second,the target field source detection antenna and different TRM array unit are designed,and linear uniform microwave field model is constructed.The electromagnetic simulation of CST is carried out to verify the feasibility of uniform microwave field based on time inversion.The distribution characteristics of the synthesized target field at the axis are analyzed.Then,the thesis analyzes the influence of TRM arrangement,TR unit number,width control factor s,spectrum loss,phase deviation and other factors on the distribution of the synthetic field and the physical mechanism.The TR unit is not equiangularly arranged,and the corresponding wave number is the advantage of uniform field generation model with equal interval sampling;the width control factor s affects the main lobe of the spectrum of the uniform microwave field,which affects the width of the synthesized uniform microwave fields,and only need to change the width control factor s to change the width of the field,without changing the model structure,showing the convenience and speed of the method;the loss of spectrum in the middle part of spectrum seriously affects the ripple and side lobes of the uniform field;by feeding different TR back transmission signals phase deviations,the effect on the uniform microwave field is studied.Finally,two methods of double point detection method and simplex algorithm amplitude optimization are proposed for the uniformity of uniform microwave field amplitude,thus confirming the usefulness of the method by CST simulation.