Synthesis of microstrip multiconductor lines, operating in normal mode

Microstrip multiconductor lines (MMCL) are broadly used in microwave areas as transmission lines, or as physical models for developing various devices: couplers, filters etc. In general case, separate waves propagate along every conductor, and interference takes place in N-conductor MMCL. Transmitted signals are not distorted if structure of propagating wave remains unchanged, i.e. normal mode wave propagates; therefore it is necessary to restrict wave propagation to normal mode in MMCL, in order to minimize signal distortion. Synthesis technique of four-conductor symmetrically coupled MMCL, operating in normal mode, is presented in this article.