Investigations on the propagation characteristics of the substrate integrated waveguide based on the method of lines

A rigorous full-wave approach based on the method of lines (MoL) is presented to analyse the propagation characteristics of substrate integrated waveguides (SIWs), in which a generalised matrix eigenvalue equation is derived instead of the conventional transcend equation, greatly improving the computing efficiency. The use of an efficient Z-transform absorbing boundary condition (Z-ABC) further improved the accuracy of the calculated propagation constants. Finally, two empirical equations are proposed for the propagation constants of SIWs, which gives a simple but efficient tool in designing substrate integrated waveguide components.