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The six T E M transmission lines are illustrated as follows:

- Coaxial line: Two metal conductors are placed one inside the other, with diameters labeled 2a and 2b for inner and outer conductors respectively. A dielectric spacing separates the two.

- Two-wire line: Two conductors with diameter d are placed inside a larger conductor, separated by a distance of upper D. A dielectric spacing fills up the larger conductor in between the smaller conductors.

- Parallel-plate line: Two flat metal plates with width w and height h between them are shown, with a dielectric spacing separating the two.

- Strip line: Two flat metal plates have a dielectric spacing between them. A metal strip is located between the two plates.

- Microstrip line: A metal strip conductor of width w and a metal ground plane are separated by a dielectric spacing, with the distance between them is labeled h.

- Coplanar waveguide: Three metal strip conductors and a metal ground plane are separated by a dielectric spacing.

The two higher-order transmission lines are shown as follows:

Rectangular waveguide: A hollow rectangular metal conductor is shown.

Optical fiber: Two thin cylindrical wires are placed one inside the other, with concentric dielectric layers separating the two.