Hi, I've been coming to physicsoforums for years, I love the community! This might be my first post though. I am wondering what the impedance is of a transmission line with a matched stub on the end. The impedance of the line is 50 Ohms, and the impedance of the stub is 50 Ohms. Is the resulting impedance 50 Ohms (simply the impedance of the line), or 100 Ohms (the impedance of the line summed in series with the impedance of the load)? I want to know for the use of a voltage division equation which occurs at the start of the tx line. Thanks!