These are some nice measurements (note that the first scope capture is measuring something totally different from the other scope captures), but there are a cou

These are some nice measurements (note that the first scope capture is measuring something totally different from the other scope captures), but there are a couple errors. First, the correct term for the apparent impedance of a long transmission line is "characteristic impedance", not "specific impedance". "Specific" means "per unit of mass". Second, the usual equivalent circuit for a transmission line is parallel capacitors separated by series inductors. The article tries a hybrid explanation with a propagating wave charging capacitors, which doesn't really work. I've been getting into microwave circuit design this year for work. One "fun" thing I've learned is that even at low gigahertz frequencies, if you want to make accurate impedance measurements with a network analyzer you have to adjust for signal propagation delays with picosecond precision. On the boards I've made, every millimeter of transmission line is about 5.56 picoseconds of delay, which is about 10 degrees of phase shift at 5 gigahertz. Parasitic inductance and capacitance also makes those nice, simple terminating resistors look at lot less simple, but that's another story...