Broadband Shielding Effectiveness Measurement System

With the increasing cognition of the harm on electromagnetic radiation, shieldingmaterials is more and more widely used by people on the military fields and civilianfields. The development of test system has become a hot spot. There are many sorts oftest methods, including the near field and far field. According to the requirements of themajor projects, In need design out a measurement system, which is the test broadbandshielding effectiveness of shielding materials. In line with the demand for testingsamples, most of them are the plate shielding material. It has wide frequency range. Thetest method is used the far field in this system，it consists of the flange coaxial cavitytest method and no reflection shielding room test method. Both of these two methodshave become mature and have been formed a specification at home and abroad.The present dissertation provides an introduction of the research background on theshielding test system home and abroad firstly. Then the research significance and thetheoretical principle of shielding system are offered. According to the designing idea ofshielded coaxial cavity shielding effectiveness measurement method used inGJB-6190-2008electromagnetic shielding materials, the author wants to design outFlange type shield coaxial cavity by using the3D design software Solidworks. Thisdesignation is completed with a brake support structure, so it makes out the jig liftinggear and it makes the flange of the coaxial inferior vena automatic lifting more flexible.The result is much more suitable for placement of the test material. Due to the design ofautomation fixture, it makes the system test more convenient and accurate. In themeantime, it can complete the flange type shield coaxial cavity test device well.In the measurement system of non-reflective shielded room test method, theshielded room was designed and formed, and it has a support frame, the height ofsupport beam is adjustable freely. And it adopted a custom0.2GHz to1GHzlog-periodic antenna,1GHz to18GHz and18GHz to40GHz broadband horn antennaand various design components to achieve the overage of the test frequency. It alsocompleted building of the whole non-reflective shield chamber measurement system.Both the two test subsystems set up a test system by using a vector network analyzer as the core instrument. According to the shielding principle for the preparationof the test system, the test software was worked out. Test on the system was carried outby using programming software and then the test results of certain several samples weregiven. Finally, the analysis results show that the stability and repeatability of the systemare relatively good and has met the requirements.