| High performance network over coax(HiNOC) is the key technology of China’s radio and television departments to achieve triple play, which is based on radio and television network, Internet and communication network. Broadband passive splitter is one of the key components to achieve HiNOC networking. In this paper, a feasible scheme is proposed for the design and implementation of broadband passive splitter.According to the 5MHz ~ 1200 MHz passive splitter insertion loss, branch loss, return loss, isolation, electromagnetic compatibility and other core technical indicators, splitter samples need to be designed and manufactured.(1) The splitter circuit PCB board is designed with the theory of microwave circuit technology.(2) According to the requirements of the branch loss of different series of splitter, through the theoretical calculation, design, fabrication and experimental validation, a special directional coupler and other key components are designed.(3) According to the realization of the return loss and isolation index, the circuit layout is optimized.(4) According to the working temperature of the splitter, circuit is used patch element with high precision and low temperature drift.(5) According to the requirement of the network installation, the interface between the branch and the coaxial cable is designed, and according to the requirements of the branch test interface, the special coaxial cable test connector is designed.(6) According to the characteristics of the branch device with moisture and humidity, electromagnetic shielding, shielding box is designed.(7) Constructing the test platform of the branch’s technical parameters, that meets the test requirements of the electrical performance parameters of the splitter, the sample is debugged and the data analysis is carried out.In this paper, the branch loss is 10 dB, 15 dB, 20 d B. In view of the wide working band of the circuit, the design of the shielding box and the interface is the integration of the electrical and mechanical design. Because the cavity formed by the shielding box can produce complex electromagnetic coupling to the transmission and distribution of the circuit signal, disturbing the isolation degree and the insertion loss of the circuit. The link between the shielding box and the interface circuit should not only meet the mechanical properties and moisture proof performance, but also meet the electrical performance index of the circuit 75 ohm impedance matching.Standard test platform is build by Agilent vector network analyzer, which can be used to test the splitter sample. The technical specifications are in line with the latest German branch technical standards, which are common in the EU market. The working frequency band is more than the current branch standard of our country to expand the bandwidth of 200 MHz in high frequency region. Insertion loss, return loss, isolation and other indicators also have a substantial increase, compared with similar products in china. The developed products can not only meet the needs of the splitter in the EU wide upgrade market, but also provide a solution for the realization of high performance branch for the three networks convergence of our country, that have a good promotion and reference for the implementation of the triple play program in China. |
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