Etched-silicon micromachined waveguides and horn antennas at 94 GHz

The realization of a diamond horn antenna in etched silicon has been suggested by Guo (1991) and by Johansson and Whyborn (1992). The latter have realized what they term to be a diagonal horn with ninety degree angles using conventional mechanical machining techniques. Anisotropic etching of silicon has become a widely used tool in micromachining of small parts, both for electrical and mechanical applications. Indeed, the exceedingly small dimensional requirements of so-called terahertz circuits virtually demands micromachined fabrication to provide the required precision. We have implemented a waveguide/diamond-horn structure operating at W-band through the micromachining of silicon using ethylene diamine pyrocathecol (EDP). The horn has been tested in a rudimentary way by measuring its H-plane radiation pattern and its gain. We have carried out an analysis of the diamond waveguide whose angles occur naturally in the anisotropic etching of silicon using finite element methods. Results of these predictions are included. To our knowledge, the work reported represents the first realization of a waveguide and of a horn antenna with controlled flare-angle using anisotropically etched silicon technology.