Fabrication and characterization of micromachined rectangular waveguide components for use at millimeter-wave and terahertz frequencies

The fabrication and characterization of micromachined reduced-height air-fi lled rectangular waveguide components suitable for integration is reported in this paper, The lithographic technique used permits structures with heig hts of up to 100 mu m to be successfully constructed in a repeatable manner . Waveguide S-parameter measurements at frequencies between 75-110 GHz usin g a vector network analyzer demonstrate low loss propagation in the TE10 mo de reaching 0.2 dB per wavelength. Scanning electron microscope photographs of conventional and micromachined waveguides show that the fabrication tec hnique can provide a superior surface finish than possible with commerciall y available components. Ih order to circumvent problems in efficiently coup ling free-space propagating beams to the reduced-height G-band waveguides, as well as to characterize them using quasi-optical techniques, a novel int egrated micromachined' slotted horn antenna has been designed and fabricate d. E-, H-, and D-plane far-field antenna pattern measurements at different frequencies using a quasi-optical setup show that the fabricated structures are optimized for 180-GHz operation with an E-plane half-power beamwidth o f 32 degrees elevated 35 degrees above the substrate, a symmetrical H-plane pattern with a half-power beamwidth of 23 degrees and a maximum D-plane cr oss-polar level of -33 dB, Far-field pattern simulations using HFSS show go od agreement with experimental results.