Sergey Dudorov

High Permittivity Dielectric Rod Waveguide as an Antenna Array Element for Millimeter Waves

Dielectric rod waveguide antennas of rectangular cross section have a number of advantages over conventional waveguide and horn antennas as an antenna array element. Dielectric rod waveguide antennas have relatively low cost, low losses, a broadband input match and a high packing potential. Additionally the radiation pattern of such antennas is almost frequency independent. In this paper the suitability of Sapphire rod waveguides for an antenna array is studied with simulations and prototype measurements at W band. Strong mutual coupling is observed when the elements are close to each other.

Analog type millimeter wave phase shifters based on mems tunable high-impedance surface in rectangular metal waveguide

Possibility of compact low loss analog type millimeter wave phase shifter was demonstrated. The phase shifter is controlled by a MEMS tunable high-impedance surface placed, e.g., as a backshort or as sidewall inclusions of a rectangular metal waveguide. Reflection type phase shifter can provide differential analog phase shift from 0° to up to 240°. Reliable and tunable MEMS based high-impedance surface has been demonstrated for the first time. The insertion loss of the fabricated MEMS tunable high-impedance surface varies from 0.7 dB to a maximum of 3.5 dB (at a resonance frequency), which is a dramatic improvement over our previous non-tunable prototype.

Microwave MEMS devices designed for process robustness and operational reliability

This paper presents an overview on novel microwave micro-electromechanical systems (MEMS) device concepts developed in our research group during the last 5 years, which are specifically designed fo ...

Micromachined 100GHz near-field measurement probe for high-resolution microwave skin-cancer diagnosis

This paper reports for the first time on a novel micromachined millimeter-wave near-field measurement probe for skin-cancer diagnosis, which is designed for high lateral resolution for resolving small skin cancer speckles as well as for vertically discriminating shallow tissue-layer anomalies. A tip size as small as 0.18 mm2, which is 18times smaller than conventional measurement tips for the design frequency of 100 GHz, could be achieved by micromachining a silicon-core tapered dielectric-rod waveguide. This metallized dielectric probe is positioned centrally into a standard WR-10 waveguide by a micromachined holder which allows for easily exchanging the probes at high reproducibility. The dielectric-wedge transition between the waveguide and the probe is optimized for 100–105 GHz. Furthermore, this paper presents a unique concept of micromachined test samples with tailor-made permittivity ranging from 1.7 to 7.1, which enables emulation of the different water content of tissue anomalies. This test method results in highly reproducible test measurements for evaluating and comparing different prototype probe designs. The paper presents successful measurement results of fabricated probes and test samples. Different single test samples as well as sample stacks with emulated tissue anomalies could clearly be distinguished.

Millimeter-Wave Near-Field Probe Designed for High-Resolution Skin Cancer Diagnosis

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 3.2-j2.3 to 7.2-j8.0, 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.

Millimeter wave silicon micromachined waveguide probe as an aid for skin diagnosis – results of measurements on phantom material with varied water content

More than 2 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. Early detection of cancer usually results in less extensive treatment and better outcome for the patient. Millimeter wave silicon micromachined waveguide probe is foreseen as an aid for skin diagnosis, which is currently based on visual inspection followed by biopsy, in cases where the macroscopical picture raises suspicion of malignancy.

Micromachined-silicon W-band planar-lens antenna with metamaterial free-space matching

In this work, we present for the first time a miniaturized planar W-band dielectric-lens antenna which is micromachined in a 300 µm silicon wafer. The antenna edge comprises a metamaterial anti-reflection geometry in order to reduce parasitic reflections at the free-space to high-permittivity dielectric interface. Furthermore, the dielectric lens is matched to a standard WR-10 metal waveguide by an optimized tapered dielectric-wedge transition. Prototype lens-antennas were fabricated in a single-mask micromachining process. The radiation pattern for the design frequency of 100 GHz was measured to 13° half-power beam-width in E-plane, a directivity of 14 dB, −15 dB side-lobe level, −15 dB reflected power for almost the whole W-band, for a lens diameter of 10 mm and an operating frequency of 100 GHz.