0 votes 0 votes Assuming perfect conductors of a transmission line, pure $\text{TEM}$ propagation is $\text{NOT}$ possible in coaxial cable air-filled cylindrical waveguide parallel twin-wire line in air semi-infinite parallel plate wave guide Others gate1999-ec + – admin asked Sep 29, 2022 • edited Dec 2, 2023 by makhdoom ghaya admin 46.4k points 109 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.