Microfabricated Silicon High-Frequency Waveguide Couplers and Antennas

A method has been developed to fabricate waveguide-to-waveguide couplers and tapered dielectric rod antennas for the millimeter-wave regime from microetched silicon. A proof-of-concept study shows that the structures can be realized using relatively simple wet etching and robotic process control. Experimental measurements of the waveguide-waveguide couplers agree in key features with simulations. The results indicate that two-stepped tapers perform nearly as well as smooth linear tapers, but are much easier to fabricate. Coupling transmissivity of better than -1 dB, and peak antenna gain of 8-10 dB are indicated at W-band frequencies. Lateral dimension etch control of 5-mum precision was realized. To solve a challenge of controlling the length of the first step, either an improved masking method or a switch to dry etching processes is required.