Packaging and metallisation effects of valley microstrip line with slit for use in very small multilayer MMICs

The authors analyse the packaging and metallisation effects of a valley microstrip line with a slit applied to practical circuits. The analysis is based on the finite difference method in conjunction with the higher order asymptotic boundary condition. The results presented here have the following interesting features: The higher order asymptotic boundary condition can put the outer boundary much closer to the centre of a valley microstrip line. As a result, much less computational effort needs to be made for accurate performance prediction; when a shielding metal box, if any, is 2-3 times the thickness of the dielectric film, the packaging effect is appreciable; for a dielectric film of micrometre order, the metallisation thickness of the valley strip and the slit ground metal have significant influence on the characteristic parameters; and the characteristic impedance and the effective dielectric constant can be adjusted by changing the oblique angle and the slit width.