Micromachined waveguide for millimeter wave applications

The micromachining of silicon is broadly proposed for the fabrication of substrates and waveguides at millimeter wavelengths. This paper presents the results of the fabrication of finned diamond-shaped waveguides by way of EDP anisotropic etching of silicon. A guide is fabricated in two halves by etching V-grooves in ⟨100⟩ silicon wafers. The etched faces of the wafers were metalized through evaporation of about 0.3 microns of gold followed by gold electroplating of approximately 1.5 microns. Metallic fins were formed on a thin membrane which was sandwiched between the two halves of the waveguide. Measurements of the dispersion curve were taken and compared with numerical calculations using the FEM technique. The comparison showed a very good agreement. An empty diamond-shaped waveguide manifests a single-mode bandwidth that is significantly less than that of a counterpart rectangular waveguide, but the bandwidth can be restored to be comparable to that of the rectangular guide through the introduction of fins