Characteristics of Multiconductor, Asymmetric, Slow-Wave Microstrip Transmission Lines

Spectral-domain technique has heen applied to analyze multiconductor, asymmetric, slow-wave microstrip lines. It is observed that 1) the coupled slow-wave microstrip line on a two-layer substrate may have substantially different propagation constants for even and odd modes and 2) the slow-wave factor of an odd mode of coupled microstrip lines on a three-layer substrate may be equal to or larger than that of an even mode under appropriate conditions. This presents the flexibility to realize a large variety of passive components, such as directional couplers, phase shifters, and attenuators.