Electromagnetic Interference Characterristics Of Microwave Circuit In Shielding Cavity

With the miniaturization and integration of modern electronic devices,integrated circuit boards become an important part of electrical and electronic equipment,and placed in the shielding cavity,the components of the circuit board are connected by microstrip lines to facilitate the exchange of information and energy.However,due to shrinking the size of circuit,the number of electronic components are more and more,so that the layout of the microstrip line is more compact,the wiring spacing is getting narrower.As the spectrum of strong electromagnetic pulse is becoming wider and wider,the interference range is more extensive and make the electromagnetic environment becomes intricate.although the printed circuit board in the shield cavity,the external strong electromagnetic pulse can still pass through the hole coupling into the circuit,then it will damage and interference to electronic components and equipment circuits.therefore,it is very significant to analysis the electromagnetic coupling problem of the printed circuit in the shielded cavity.In this paper,the basic principle of Finite Difference Time Domain is introduced.a hybrid algorithm combination of non-uniform meshing principle and Lumped-Element FDTD method,it is used to solve the problem of electromagnetic interference in microstrip circuit.build a electromagnetic interference model of parallel coupling microstrip line with electromagnetic wave irradiation.due to microstrip line and the lumped element on the microstrip circuit are fine structure,the coarse region is used to divid the large area of computational space,then in the area near the microstrip circuit using the gradient step,thtough the grid gradient,the microstrip circuit with fine grid.considering the size of actual electronic components is larger than fine grid,therefore,the lumped elements need to span multiple grids.Therefore,the multi-grid lumped element FDTD method is applied to lumped elements on the basis of non-uniform FDTD,to achieve fast calculation of electromagnetic coupling analysis of microstrip circuit board.The correctness of the hybrid algorithm is verified by comparing with the FDTD algorithm and the commercial simulation software.Secondly,electromagnetic interference characteristics analysis of the simple microstrip circuit and calculation.The non-uniform FDTD hybrid algorithm is used to analysis the polarization of the space electromagnetic wave a,the microstrip line spacing d,microstrip line width w,microstrip line length 1 influence on coupling voltage on terminal load of parallel microstrip circuit.Some electromagnetic coupling laws of microstrip circuits in free space are obtained.Finally,the integrated circuits of modern electronic devices are mostly in the shielding cavity,consider electromagnetic interference of microstrip circuit effect of shielding cavity.build an electromagnetic interference model of the microstrip circuit in the shielded cavity.The correctness of the hybrid algorithm was verified by comparing with the simulation result of the commercial simulation software.Then,the shielding effect of the shielding cavity was analyzed,and the microstrip line spacing d and the position of PCB(printed circuit board)impact on the electromagnetic interference of the microstrip circuit,get the change rule of the induced voltage on the load resistance.the results show that the electromagnetic interference characteristics due to the microstrip circuit structure change are consistent in the free space and in the shielding cavity.