Effects of misalignment on propagation characteristics of transmission lines printed on anisotropic substrates

The spectral-domain method is applied to study the propagation characteristics of grounded transmission lines on biaxial substrates whose axes are misaligned with those of the line. The three structures under investigation are the grounded slotline, microstrip, and the edge coupled line. In the formulation, an expression for the Green´s function that is valid for substrates which are simultaneously characterized by their permittivity and permeability tensors is derived. The off-diagonal elements of the permittivity tensor, present due to the misalignment of the axes, are used to examine the dispersion properties of these transmission lines with numerous case-studies presented for different angles of rotation