Strip coaxial cable: monofilar and bifilar modes

A theory is presented for the study of the propagation characteristics of electromagnetic waves in a strip coaxial cable. Two propagation modes (monofilar and bifilar) are studied for different configurations of optical coverage and different numbers and width of the outer conductor strips. The surface transfer impedance is also evaluated. It is shown that the propagation constant of the bifilar mode is close to the wave number for the dielectric inside the cable, while the propagation constant of the monofilar mode is very nearly equal to the free space wave number. The surface transfer impedance of a TM (transverse magnetic) mode has an imaginary part which is less than zero for the monofilar mode and greater than zero for the bifilar mode