Dispersion properties of four and five coupled microstrip lines in suspended substrate structure using hybrid mode formulation

In this paper, a full wave modal analysis is performed on four symmetric and asymmetric parallel-coupled microstrip lines and symmetric five-coupled microstrip lines in suspended substrates structures. The numerical procedure based on the modal analysis, is formulated to compute all the frequency-dependent normal mode parameters of four coupled microstrip lines structures. These parameters include phase constant, modal impedances and the dielectric losses of the coupled four lines for all four propagating modes. In addition, attempts have also been made to compute the propagation constant of various propagating modes of five-coupled microstrip lines of equal width and spacing in microstrip lines structure as well as in suspended substrate structure.