The authors propose to use microelectromechanical systems (MEMS) to produce novel phase shifters based on an electronically reconfigurable high-impedance surface (HIS). Typically, HIS is a textured metal surface with reactive impedance varying from an initial value to a very high value. Such phase shifters can be developed with introducing a surface with variable impedance in, e.g., a rectangular metal or dielectric rod waveguide. Placed along narrow walls of the rectangular metal waveguide or adjacent to the dielectric waveguide, the HIS affects the propagation constant, which results in changing the phase of the propagating wave. The authors manufactured a prototype of the microelectromechanical systems-based HIS consisting of a dielectric layer placed on a ground plane, and two arrays of metal patches. The gap between the upper and lower arrays of patches was fixed and filled with SiO 2 . The measured phase of the wave reflected from the prototype HIS varies in the range of 50°, and its insertion loss is below 0.5 dB (out of resonance).
This paper presents a detailed technical characterization of a micromachined millimeter-wave near-field probe developed for skin cancer diagnosis. The broadband probe is optimized for frequencies from 90 to 104 GHz and consists of a dielectric-rod waveguide, which is metallized and tapered towards the tip to achieve high resolution by concentrating the electric field in a small sample area. Several probes with different tip sizes were fabricated from high-resistivity silicon by micromachining and were successfully characterized using silicon test samples with geometry-defined tailor-made permittivity. The probes show a high responsivity for samples with permittivities in the range of healthy and cancerous skin tissue at 100 GHz (from to , loss tangent of approximately 1.26). The sensing depth was determined by simulations and measurements from 0.3 to 0.4 mm, which is adapted for detecting early-stage skin tumors before they metastasize. The lateral resolution was determined to 0.2 mm for a tip size of 0.6 0.3 mm, which allows for resolving small skin tumors and inhomogeneities within a tumor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.