Electromagnetic Compatibility Test And Design Based On High Concurrency Network Scenarios And Frequency Selective Surface

With the deepening of the degree of mobile networking and the increasing development of social information construction,the need to complete various data collection,forwarding,processing and pushing through the system is also increasing.At present,EMC test is also faced with the problems of increasing data volume and complex test content.At the same time,it is necessary to record the use of instruments and equipment before and after the test.In order to improve efficiency,multiple tests will be carried out simultaneously.Therefore,in the face of the increasing scale of EMC tests,it is necessary to build a system based on high concurrent network scenarios to assist various EMC tests and improve the test efficiency.The EMC test system designed in this paper is based on the current network background using network communication technology,data storage technology,operation flow log technology,fast data access technology,efficient data processing technology to EMC test process for all-round management and operation of the system platform.Based on advanced modern management design and intelligent layout concept,the system improves the operating cost and working efficiency of EMC testing,and provides an advanced technical fulcrum for comprehensively enhancing the testing level.In the process of EMC testing is a very important link is to eliminate the environmental electromagnetic interference,often use the shield layer or shield cavity to reduce the error,which is of vital significance to improve the accuracy of testing,at the same time,the high performance shield layer is also an essential element in the current electronic products.Metal shell is often used as the shielding layer of electronic devices or PCB from electromagnetic interference(EMI)and radiation.It is important to eliminate environmental interference in electronic products.In some cases,if the shell has a large area and thickness,it will result in high shielding cost and heavy electronic devices.In addition,in the fifth-generation(5G)communication environment,wireless signals of higher frequency band than before reach the interior through the hole and slot coupler on the metal shell,causing electromagnetic interference,which brings great challenges to the design of the metal shell.Therefore,this paper focuses on the research and design of three frequency selective surfaces to replace the metal cavity shielding.This paper mainly includes the following research contents and results:(1)A frequency selective surface(FSS)based metamaterial structure with holes is proposed for 5G electromagnetic(EM)shielding.The proposed FSS can not only realizes the compact dual band-stop characteristics of close distance successfully,but also improves the ventilation and heat dissipation capacity compared to metallic enclosure.Taking-10 dB as the threshold for bandwidth measurement,the proposed FSS has two stop bands with central operating fi-equencies of 3.5GHz and 4.86GHz.The first suppressed bandwidth can reach 1.17GHz and the second can reach 0.67GHz,which can effectively cover the working frequency band of 5G mobile signals,and has a stable response to TE and TM polarized electromagnetic signals.(2)A compact and high performance shielding enclosure designed by metamaterial structure based on frequency selective surface(FSS)is proposed.The enclosure has large holes for convenience of airflow and cable access.However,it can maintain more than 40 dB shielding effectiveness(SE).This design shows promising capability of size reduction,bandwidth expansion and shielding effectiveness(SE)enhancement.Moreover,the enlarged holes on the FSS is helpful for the ventilation and heat dissipation.The size of the proposed 2.5-D FSS is only 0.097 ?0 ×0.097 ?0 where ?0 corresponds to free-space wavelength of resonance frequency.The proposed structure provides 3.38 GHz(3.21 GHz-6.59 GHz)wide shielding bandwidth.Furthermore it has stable response to the wide angle incident wave ranging from 0° to 85° with more than 40 dB SE at the 4.83 GHz for both TE and TM modes.(3)In this chapter,an ultra-thin frequency selective surface structure with high bandwidth is proposed.The unit size of the proposed FSS is 0.32?0 ×0.32?0,and miniaturization is realized.It exhibits a wide stopband of 35 GHz with attenuation more than 40 dB at central operating frequencies for the normal incidence.Since it is working in the U-and V-bands,it can be used for millimeter-wave shielding applications and for mutual coupling reduction.And its resonance frequency can be tuned by adjusting loads and the loop radius.(4)This paper uses NodeJS technology to develop network services and build application platforms conveniently and quickly,and to build an information-based EMC test system.The system adopts the Express component and based on the MVC design pattern to build the overall structure of the platform,organize all levels of the server,and form the hierarchical system structure of network foundation,database,basic Web service and advanced Web service.In the advanced Web service,the front-end and back-end HTTP requests are processed.The view layer uses a progressive framework to realize the data binding of response,combine view components and dynamically generate HTML pages through API as simple as possible.The basic Web service mainly manages all kinds of data of the platform and provides data support to the controller as required.At the same time,the database,basic Web service and advanced Web service are respectively modularized,so that each module has its own input and output interface,and each module is coupled through the input and output interface to complete system functions.This design can be further extended to the application of WLAN,ISM,GSM and Wi-Fi shielding.