Shielding Effectiveness Test System Of RF Coaxial Cables

With increasing degree of complexity of electronic system and electronic device, in the same circumstances, there may be a variety of systems or devices, the requirements of electromagnetic compatibility of these devices or systems will also be increased accordingly and become rigor. In order to reduce the electromagnetic interference between each other, reduce the effect between the devices or systems, and ensure the smooth and efficient operation of the overall environment, shielding measures must be taken of in all components of a system, especially the connecting cables and the cable assemblies. Therefore, measurement methods of shielding effectiveness become an extensive hot research spot increasingly for cables or components. RF coaxial cable as the connecting cable in one of the important, there are a variety of testing methods of the shielding effectiveness of the RF coaxial cables.This paper adopts triaxial method and reverberation chamber method to constitute a set of RF coaxial cables shielding effectiveness test system of 500 MHZ to 18 GHZ radio frequency. In triaxial method, the measurement for coaxial cables is mainly two kinds of methods, namely transfer impedance and shielding attenuation. In more than 30 MHZ band, coaxial cables' shielding effectiveness be concerned with its length,the shielding attenuation is measured, in the below 30 MHZ band, coaxial cables' shielding effectiveness has nothing to do with its length, the transfer impedance is measured. The subject of triaxial method test system, the "short circuit-short circuit " structure and the method of direct measurement of shielding attenuation were adopted, a set of 500 MHz-1 GHz test device was designed. In the process of building the system, we first analyzed theoretically and design the structure and size of each part, then the simulation, optimization, the final design, finally, the processing and measurement. Using Auto CAD software to draw the parts and assembly drawings, it makes the process convenient. In the high frequency part, reverberation chamber was be used. By rotating the mechanical stirrer, fully shielded cavity will be obtained the uniform, randomly polarized and isotropic electric field distribution. By oscillation and reflection of electromagnetic waves in the cavity can produce larger electric field intensity. EUT can be accurately measured the shielding effectiveness in this environment. In some universities, institutions and other places, the construction have the corresponding research of the reverberation chamber test system, but the instance is still less. In a variety of testing methods, reverberation chamber belongs to a more innovative and cutting-edge category. The system operation is simple, cheap and widely used. Reverberation chamber method can measure not only coaxial cables shielding effectiveness but also other components. It also can be used for other relevant electromagnetic interference test. The subject in the international standard under the premise, a complete set of reverberation chamber test system was constructed. The most important stirrer indoor reverberation chamber was simulated and optimized using HFSS simulation software to determine the best solution, so that the interior reverberation field uniformity can reach the optimum. After building the real, be in progress to uniformity test of reverberation chamber and actual measurement of coaxial cables, repeat the test on the coaxial cable RG59 and coaxial cable FFJ216A-3#, FFJ216A-2#? FFJ216A-3#?UFB205A-1#?TFLEXRG402-3#, these four kinds of coaxial cables contrast test were carried out. Through the comparison of the results obtained, the design of reverberation chamber system has been successfully completed.