Calculation of the line parameters of quasi-planar waveguides for millimeter-wave integrated circuits

Mechanical accuracy requirements for waveguide components become more exacting in connection with the use of such components for operation in the millimeter-wave region. Changes in a circuit make it often necessary to construct a new waveguide component. For these reasons, investigations are being conducted with the objective to design millimeter-wave circuits which employ new types of line structures. A number of such structures is considered, taking into account the image guide, the inverted strip image guide, the trapped image guide, the groove guide, the H-guide, the comb guide, the unilateral fin-line, the bilateral fin-line, the antipodal fin-line, the coplanar fin-line, the microstrip line, and the bilateral suspended substrate line. The calculation of the phase coefficients for the waveguides is discussed, giving attention to the use of the equivalent transmission line concept reported by Itoh (1980). The calculation of the line impedance is also considered, and numerical results are presented.