A finite ground coplanar line-to-silicon micromachined waveguide transition

Circuits operating in the terahertz frequency range have traditionally been developed using hollow metal waveguides, which, due to the small wavelengt h at these operating frequencies, must be correspondingly small in cross se ction. As a result of the high cost of conventional precision machining of such small waveguides, alternate fabrication methods continue to be explore d. Silicon micromachining has been suggested as a potential means to produc e waveguides in a more cost-effective manner for operation at these frequen cies. This paper presents a transition structure that couples the popular f inite ground coplanar transmission line to a W-band silicon micromachined w aveguide, forming a fully micromachined module. The waveguide is formed via bulk micromachining using a wet etchant, resulting in a diamond cross sect ion. The consequences of utilizing a diamond waveguide in place of the more common rectangular waveguide are considered and potential means of develop ing rectangular-walled waveguides in silicon are noted. A K a-band microwav e model of a similar transition to a conventional rectangular waveguide is also demonstrated.