https://www.ittc.ku.edu/~jstiles/723/handouts/
https://www.ee.iitb.ac.in/course/~dghosh/uWave.pdf
https://www.youtube.com/@basicbuildingblocksofmicro829
https://www.microwaves101.com/encyclopedias/transmission-line-loss
Power flow derivations in Transmission lines
Directional Coupler terms
directional coupler wiki