Microwave Automatic Impedance Matching System

Microwave impedance matching refers to the condition that, the reflection at the system terminal or at the joints which are connected by transmission line with different characteristic impedance, is zero all the time in the process of microwave signal transmitting. The matching mentioned relates to the system transmission efficiency, power capacity and stability, and it also relates to the fixed error and measuring accuracy in the process of microwave measurement. Therefore, the matching is not only an important part in the microwave technique, but also a significant aspect of the microwave systems. It is difficult for traditional microwave impedance matching technique to provide a simultaneous, rapid and stable matching, when it is confronted with impedance nonlinear variation that represented by dynamic load impedance, which largely limits the application of the microwave system in many fields.In this paper, it introduces an automatic impedance matching system that can accomplish matching with the dynamic load impedance in highpower microwave system. Using its two characteristics-fully automatic and rapid, this system can accomplish simultaneous, rapid, stable and repeatable matching with the load impedance, especially the dynamic load impedance (eg: plasma load). At the same time, it maintains the reflection coefficient at the desired value (eg: 1.2) to assure that the microwave transmission is at its best.. Based on the automatic impedance matching system mentioned, this article puts forward a new rapid matching approach. Changing the depth of penetration of the three dowels results in the variation of the reflection coefficient ( S1 1) at the port 1. Using MATLAB, we can calculate different equivalent impedance of port 1 which resulted from the variation of dowels depth. The purpose of my work strike up a relationship between the depth of dowels and equivalent impedance at port, thereby accomplish matching rapidly, simultaneously and stably.