There is an excellent free program for Windows that really helps to understand how transmission lines work. It is called TLDetails >>
Using this program you can select from commonly available transmission lines (RG8, RG58, twinlead etc.), set a load impedance, cable length and frequency and then it calculates the SWR, Return Loss, impedance and plots on a Smith Chart. Many other useful features as well. Here is an example.
Roger Need
