Study On Multi-resolution Electromagnetic Simulation And High Resolution Imaging Method For Complex Small Target

A small-scale target refered to a target with a relatively small scale in each research field.The definition of the concept of "small scale" was different in different fields.However,due to the complex structure of the small scale target,the resolution requirements were continuously improved,and the detection task became more and more difficult,which challenges the capability and method of the existing detection equipment.In the past,the equipment had been manufactured,and the theory or method was presented according to the equipment applications.This would lead to the disadvantage of the detection work,even if the signal processing was highly treated well,the detection requirements couldnot be met.Therefore,the manufacture of modern instruments needs to achieve theory and technology,a large number of simulations to get the distribution characteristics of the field,and propose new imaging methods.Based on these works,the instruments can be manufactured.The detection of complex small targets was a difficult problem in the electromagnetic detection.This detection work required not only the rich harmonics to meet the resolution requirements,but also the optimization of the radiation source improved the radiant energy and conversion efficiency.In addition,multi-resolution and multi-scale information extraction techniques should be added to further improve the resolution of instrumentation.At present,the detection concepts of complex excitation,complex received signals and multi-resolution signal processing were used to solve the issue of insufficient radiation capability,insufficient resolution and poor anti-interference ability of the radiation source in the current detection mission.For the detection of complex small targets,traditional radiation sources had bottlenecks in the emission process,and difficult to achieve high-resolution.Therefore,in order to obtain a clear resolution,it was necessary to modify the radiation source and detection techniques,optimizing the structure of the radiation source,increasing the radiation level,and expanding the harmonic range.In order to make a concrete and common result in this dissertation,we started from the detection issues of three different fields and solve the high-resolution detection problem of complex small targets one to another.For the early detection of brain tumors,this dissertation used the transient electromagnetic array source as the radiation source,optimizes the radiation pulse,and uses the apparent dielectric constant imaging method to solve the early detection issue of glioma;Using high-performance transient electromagnetic ‘horn' radiation source and optimizing the radiation pulse,can solve the early warning issue of space debris in out space;using high-performance transient electromagnetic "horn" source,multi-resolution technology and multi-scale information extraction technology,and wave transformation and migration imaging technology,solve the issue of multi-scale detection of urban underground space.It was obvious that the same factors exist in the detection work of the above three fields,that is,according to the physical properties of the measured objects,it was necessary to optimize the detection equipment.Taking the optimal pulse selection as an example,there was always a pulse that was most suitable for detecting a specific material and scale.If the optimized radiation pulse was not selected,the resolution of the detection will be lost to different degrees,which was not conducive to the detection of the problem.Taking the multi-scale target detection of urban underground space as an example,it was not enough to select only one set of detection pulses because the target scale was different.To solve the detection problem of multi-scale target,it was necessary to use multiple sets of pulses.Scanning the specific multi-scale targets compensated for the lack of effective harmonics for a single pulse.The above examples illustrate that it was necessary to fully understand the excitation process of the radiation source,the response of the target,and other factors before manufacturing the detection equipment.Blind manufacturing of equipment did not improve the detection efficiency of the radiation source,and may even fail to achieve the desired detection results.With the development of modern detection technology,it was no longer limited to a single radiation source,a single radiation pulse and other simple detection methods.With the complexity of the structure and material of the target object,the corresponding detection methods needed to be continuously improved.The era of serving the target of measurement will eventually become the trend of scientific development.