Theotical Research On Radiation Source Design Of Microwave Staring Correlated Imaging

As a novel computational radar imaging technology,Microwave Staring Corre-lated Imaging(MSCI)obtains superior imaging result without the relative motion be-tween the radar system and the imaging targets,meanwhile achieves continuous ob-servation of the targets with high imaging resolution.The essential of high resolution MSCI is to construct the temporal-spatial differentiated radiation fields in the imag-ing region,and to implement the corre,sponding design of the radiation source.In this dissertation,aimed at achieving higher imaging resolution,obtaining better imaging results,improving detection efficiency and realizing more practical system design in MSC.I,we focus on the theory and method for MSCI radiation source design based on the requirement of radiation fields in MSCI and the relationship between the radiation source parameters and radiation field characteristics,and investigate practical realiza-tion methods of MSCI.The research work of the thesis includes:1.The imaging model is re-derived based on aperture source of the transmitting array,and the imaging equations in integral form and matrix form are obtained.From the perspective of solving the imaging equation in matrix form,the evaluation criterion of the radiation fields and radiation source is introduced as imaging matrix properties such as matrix rank and condition number.The characteristics and constructive patterns of the optimal radiation fields are discussed.And finally,the design principles of the radiation fields are concluded.2.From the radiation process of the surface source,the relationship between the ra-diation source parameters and the radiation fields is established.Based on the proposed evaluation criterion of the radiation fields,design requirement of radiation source for achieving full-rank imaging matrix is analyzed under the given imaging geometric con-figuration and resolution demand.To realize the optimal radiation fields for microwave staring correlation imaging,radiation source design methods based on the solution of the radiation equation and the orthogonalization of the sensing matrix are proposed.Imaging matrix optimization method is applied to decrease the condition number of the imaging matrix and achieve well-behaved imaging performance,with the utilization of Simulated Annealing(SA)random search algorithm.Coherent integration method is also introduced into MSCI to further improve the imaging quality.3.The existing MSCI system commonly adopts the synchronous radiation of mul-tiple transmitting antennas to generate the required temporal-spatial stochastic radiation fields,which puts forward high requirements on the synchronization and consistency of the multiple transmitters,and remains underutilization of the available design resources.In this dissertation,a time-division MSCI(TD-MSCI)method instead of synchronous radiation is proposed.The basic observations of the imaging targets are formed through the separate radiation of each individual emitting channel,and then the digital wave-form synthesis is used to virtually and equivalently generate the required stochastic radiation fields by randomly combining the basic individual radiation fields.Compa-rable imaging performance to synchronous radiation MSCI can be achieved under the same combination of radiation parameters,and improved matrix property and imaging performance are realized by taking further utilization of the given radiation resource.Simulation experiments and imaging experiments in microwave anechoic chamber are conducted to verify the effectiveness of the proposed TD-MSCI method.4.The feasibility and implementation of high resolution MSCI with simplified sys-tem architecture are investigated.In the MSCI imaging system with multiple transmit-ters emitting random frequency hopping waveforms,each transmitting channel needs to be controlled individually to synthesize waveforms at different frequencies,which in-creases the system complexity and introduces multiple kinds of errors.Meanwhile,the transient effect of the radiation fields with random frequency hopping waveforms makes it hard to implement high precision measurement of the transient radiation fields and calibrate the imaging system with the corresponding observation result of the fields.The feasibility of realizing MSCI with single transmitting antenna rather than multi-ple emitting antennas is discussed,and relative simulations are conducted.From the perspective of implementing the transmitting antenna,a configuration of multiple an-tennas with coherent excitations is utilized instead,to generate steady radiation fields sequence with different distribution patterns.With the proposed Simulated Anneal-ing based radiation source optimization method,the radiation parameters of the steady radiation fields sequence MSCI(SRFS-MSCI)are designed and optimized,and high resolution imaging results can be obtained through the difference of fields patterns with different observation parameters.Simulation experiments and imaging experiments in microwave anechoic chamber are conducted to verify the effectiveness of the proposed SRFS-MSCI method.