Impedance Matching by Using a Multi-stub System

Nowadays lots of applications in telecommunications require a wide bandwidth to transmit more information and improve the quality on the transmission of this information. In order to guarantee this condition low losses systems are designed; these losses can be classified in dissipation losses and mismatch losses. There are different classic methods for impedance matching, but they reach the impedance matching in a very narrow bandwidth, whereas the bandwidth used in different applications is generally greater in accordance with the quantity of information to be transmitted. A solution proposed in this paper to reach an impedance matching into a wider bandwidth is through the connection of various stub lines in parallel all along the transmission line, so we can have a multiple variables system, with more grades of liberty. A software that automatizes the calculations to reach the impedance matching was programmed, by using the minimum squares and Nelder-Mead methods. Once the user introduces the data of Standing Wave Ratio (SWR) and bandwidth desired, the load impedance and the work frequency of the system, the program determines the minimum number of stubs necessary to match the system, and the longitudes and distances along the line where they should be located. Key–Words: SWR, stub, impedance matching, optimization