where [A.sub.a], [A.sub.s] are the boundary conditions for asymmetric and symmetric modes respectively, k is the wavenumber, d is the
half thickness.
The resistance of the coupled lines can be calculated through microstrip lines with the same width and
half thickness of the substrate.
Notice that the analytical solution is accurate only for small displacements, generally for maximum transversal displacement smaller than the
half thickness of the plate.
integrating the continuity equation through the
half thickness of the fluid i gives the following expression: