Simulation Modeling Apertures And Study Field Distribution In Small Enclosure

With the rapid development of electronic information technology,electromagnetic interference is becoming more and more serious.Shielding technology is an effective method to suppress electromagnetic interference.However,external electromagnetic interference can still be coupled into the enclosure through apertures.Therefore,it is necessary to carry out the simulation modeling of aperture and study the field distribution inside the small enclosure,which is of great significance to the design of shielding enclosure.In this paper,a transfer impedance test device for conductive gasket with upper frequency limit of 18 GHz is developed.The measurement shows that the transfer impedance test device have a voltage standing wave ratio(VSWR)lower than 2 in the frequency range of 10 kHz up to 10 GHz and lower than 4.1 in the frequency range of 10 GHz up to 18 GHz.Based on the test results of transfer impedance of conductive gasket and the principle that the leakage of electromagnetic field of equivalent model is consistent with that of the original model,the conductive gasket is equivalent to isotropic material.The equivalent electrical parameters of the aperture in the enclosure with conductive gasket are solved by particle swarm optimization(PSO),and the equivalent electrical parameters of the aperture in the enclosure with conductive gasket are determined.In this paper,the simulation method and test technology of shielding effectiveness of enclosure are studied.Focusing on the frequency range of the electrically large size,using the plane wave superposition to simulate the reverberant field and the parameters of the randomly generated plane wave are analyzed.Using MATLAB-FEKO to simulate reverberation chamber and statistical test of superimposed field environment,the correctness of the method of plane wave superimposition to simulate reverberation field environment is verified.On this basis,the equivalent electrical parameters are used to characterize the simulation aperture with conductive gasket,and the reverberation field generated by plane wave superposition is used to illuminate the enclosure.The shielding effectiveness of theenclosure is calculated based on spatial sampling method.The reverberation chamber method is used to study the shielding effectiveness test technology of the enclosure in the under-mode and over-mode frequency bands,and the accuracy of the simulation results is verified by the measured results.The differences between the results of different testing methods are compared and analyzed,and the suggestions of shielding effectiveness testing methods are given.The field distribution of small-sized enclosure is studied in this paper.According to the internal resonance of the enclosure,it is divided into three frequency bands: non-resonant mode,under-mode and over-mode.The non-resonant mode and under-mode frequency band are analyzed by simulation results directly.Statistical analysis of simulation results are used in Over-mode frequency band.Combined with FEKO software,the internal field distribution of the enclosure in three modes is studied in depth.The field distributions of different frequency bands in the enclosure are obtained.