Research On Electromagnetic Shielding Performance Testing Technology Of Materials

With the increasing power of electronic devices,lower and lower reception sensitivity,and increasingly serious electromagnetic pollution,electromagnetic shielding and electromagnetic interference have become important factors that must be considered in electronic designs.In order to reduce electromagnetic pollution and improve equipment anti-jamming capability,it is necessary to add a layer of shielding material around the radiation source and in the part that resists electromagnetic interference.The selection of shielding materials is particularly important,and the electromagnetic shielding effectiveness of materials is one of the indispensable parameters.Traditional shielding test systems are bulky,heavy,and costly,which greatly limit the application of shielding performance testing.This paper focuses on material shielding performance tests,and carries out researches on small,lightweight,low-cost shielding material test systems,which has important research value and practical value.Firstly,this paper briefly describes the background,research significance and dynamics of the shielding test system.Then the principle of shielding performance test is described in detail.According to different application scenarios,two sets of shielding material performance parameters test fixtures are designed.1.Using the structure of coupled microstrip line for miniaturization design,using electro-magnetic coupling theory and HFSS software to optimize the design of coplanar wave conducting and magnetic probes,respectively,to create a coupled microstrip line,electromagnetic coupling probe and three-dimensional movement of the probe Device,and set up a 10 MHz ~ 18 GHz coupled microstrip line material shielding performance test fixture.The fixture has the functions of parallel stripline crosstalk before and after loading the samples,transmission line insertion loss comparison test,and quick and convenient test of the radiation energy around the transmission line,and provides the comprehensive parameter acquisition of the shielding performance and transmission performance of the sheet material in the microstrip application.2.A square coaxial cavity with an impedance of 50 ohms was designed using a square coaxial transmission line.The matching transition from an N-type connector to a square coaxial cavity was optimally designed using coaxial transmission line theory and HFSS software,and the matching structure from an N-type connector to a square coaxial cavity,the square coaxial transmission line and sample positioning device were created.And a 1MHz ~ 1GHz square coaxial material shielding performance test fixture was set up as well.At the same time,based on the structure of the shielding system,a material reflectivity test fixture using short ending square-axis transmission line was designed and fabricated.The fixture has features such as small inner conductor cross section,low sample preparation difficulty,and a field distribution similar to a uniform plane wave.Low-band slab materials provide effective testing methods for acquiring comprehensive parameters of shielding performance and reflection performance in the plane wave state.Using the two sets of material shielding performance test fixtures developed above,combining with a vector network analyzer to build a test system,with which a shielding performance test was conducted for different types of materials and different sizes of samples,and the actual test results were obtained.Finally,the test results were analyzed for errors.The two sets of test fixtures established can provide a basis for evaluating the shielding performance of materials.