AUTOMATIC IMPEDANCE MATCHING CONTROL SYSTEM BETWEEN -SOURCE AND LOAD

Abstract

This dissertation mainly concerns about a basic problem in RF technology of Impedance matching between source and load. There are many applications of RF where continuously changing load increase reflected power towards source, thus transmitted power to load decreases, as a consequence source malfunctioning and losses increase. This topic basically provides knowledge about impedance matching between source and load, not only this but how automatic impedance matching control system can be designed for a varying load such as PLASMA chambers and Microwave ovens. Other applications of impedance matching control system are Acoustic systems where the impedance of diaphragm keeps on changing because the incident frequency on the same changes which again needs impedance matching between the reflector and the receptor diaphragm. This topic encloses a basic knowledge about the impedance matching, how it can be achieved? How some of the soft computing techniques can be used for matching the impedances. Not only this but this dissertation discusses about some of the instruments that can help to find the RF characteristics of the network. The working frequency is considered to be 13.56 MHz (being a non-patented frequency for research). This being low frequency only lumped elements can be used for the matching purpose. A study for two and three element matching has been done and for simplicity and reduced complexity controller for two element matching network has been designed and results for the same are discussed. A fuzzy logic controller for the same has been designed and the comparison between the ideal controller and fuzzy controller has been established. Effects of delay in matching have been studied and the results for the same have been included in the report. The variations in the element values with respect to changes have been included in the report. ix