Study On Multiconductor Transmission Lines In High Frequency Environment

For communication equipment manufacturers, equipment testing is an indispensable part in the process from equipment development to application. Before testing equipment, developers must build testing environment, which will use many cables. But the cable itself has limitations, which are reflected in two aspects. On one hand, the cable is expensive, so the manufacturers need to spend a lot of money to buy cable. On the other hand, test scenarios are constantly switching during the testing process, which requires a lot of people to carry the cable frequently. But the cable itself is very heavy, which brings difficulties for people to carry cable. The limitations of the cable lead to the low efficiency of the test. In order to solve the problem of low efficiency in testing, this paper studied the transmission line used in the test environment.In this paper, we studied multi conductor transmission line in the test environment, and then we established the equivalent circuit model of transmission line. The circuit model is the synthesis of the mode of multiple single conductor transmission line and the interference model of transmission line. For the single conductor transmission line model, a two-level passive network is established by means of passive network synthesis. For the transmission line interferenc e model, the capacitance and inductance matrix are established by analyzing the coupling path between the transmission lines. Then we quantified the mathematical model respectively by the means of charge method and energy method. Then the equivalent circuit model of the multi conductor transmission line was verified and applied in this paper. We designed the transmission line simulation board. The transmission line simulation board can realize the attenuation and crosstalk performance simulation of single port or multiple ports in cable. Furthermore, this transmission line simulation board improved the operating frequency range comparing the other transmission line simulator. The effective operating frequency range of the transmission line simulation board in this paper was 0~85 MHz, which has been verified by the actual testing. But the effective operating frequency range of the transmission line simulator in the current market only was 0~30 MHz.The transmission line simulation board was currently used in Huawei. It was mainly used to solve the problem of low efficiency caused by the actual cable.