Microwave Circuits Review Part I

3.5. Coupled Lines Theory

Even and Odd Modes

Any pair of voltage excitations V1,2 at the input  terminal can be resolved into even and odd modes components:

V_1,2 = V_e±V_o, where V_e = (V₁ + V2)/2, V_o = (V₁ – V₂)/2.