Toshitatsu Suzuki

Near-Field Transmission Imaging by 60 GHz Band Waveguide-Type Microscopic Aperture Probe

Near-field imaging has been intensively investigated to observe the shape and the physical properties of objects, aiming at wide applications in the areas of science and engineering. In this research, by using 60 GHz band waveguide-type microscopic aperture probe, the characteristics of the near-field imaging in transmission mode have been studied by simulation and experiment. The probe is made of a WR-15 rectangular waveguide with end-shielded metal plate and a 0.5 mm-diameter aperture. In the simulation, at first, the electric field distribution at the aperture, at the rear (waveguide) and the front positions (free space) are presented. Second, the transmitted electric fields are presented for three cases: (a) scanning of a dielectric slit, (b) by varying the distance between the aperture and a dielectric sample, and (c) scanning of a dielectric groove. In the experiment, the lateral resolution with a two-slit and the depth resolution with grooves having various depths in rectangular format are described and the results show both resolutions to be much shorter than the wavelength. Finally, the scanned images of the letter N punched through a dielectric material and a leaf are demonstrated.

In-depth measurement of 60GHz band near-field and transmission mode microscopy

The study on the near-field microscopy at the millimeter- and submillimeter-wave bands has been flourishing for diagnosis of bio-, nano- and micro-structures. In this research, the in-depth detection capability in the near-field by the transmission mode measurement at 60 GHz band has been investigated. First, the groove engraved with various depth of 0.1- 0.9 mm, the in-depth resolution is 0.5 mm. Second, the voids with 1 mm-dia are formed by various in-depths at 0.5-10 mm under the surface of Teflon. The void down to 2 mm can be detected. Final, a pore on the TiO2 sheet with the thickness of 2.4 mm, it is shown in scanning the surface that a pore with about 0.8 mm-dia located at the surface can be detected.

Local Dielectric Measurement by Waveguide-type Microscopic Aperture Probe

For dielectric constant measurement of areas smaller than the wavelength, this paper proposes a method of employing waveguide-type microscopic aperture probe. The probe is made of WR-15 waveguide with one end shielded with metal plate of 0.3mm, on which a 0.5mm-dia or a 0.1mm-dia aperture is made. The dielectric constant is derived from the slope of phase difference swept over 50-70GHz between the cases of free-space transmission with and without the dielectrics. In order to evaluate the system, the dielectric constant of Teflon has been measured by three cases of using the probes of 0.5mm-dia and 0.1mm-dia, and two V-band corrugated horns. The results show good agreement.

Microscopic structure imaging with phase analysis at 60GHz band

This study aims imaging and permittivity measurement for microscopic structure at 60 GHz band. Main device is the waveguide type probe which has a 0.5 mm aperture on the terminal wall. Using this probe, a cherry leaf is measured as a demonstration of thin film measurement. Permittivity is obtained on vein and mesophyll. Image is obtained for 5times2.5 mm region with 0.25 mm step.

O/sub 2/ concentration characteristics at 60 GHz band and diagnosis of temperature, pressure and concentration

Toward the embodiment of in-situ gas sensors capable of simultaneous measurement of composition, temperature and pressure, this paper presents (1) spectrum measurement of O/sub 2/-N/sub 2/ with various mixing ratio at 60 GHz band, (2) derivation of concentration dependent spectrum model, and (3) the diagnosis of temperature, pressure and concentration using the derived model and downhill simplex.

A Compact Modified Meander Resonator for Microwave BPF with Harmonic-Suppression for 3G Mobile Communication System

This research presents a compact modified-meander resonator which has implemented to a microwave narrow bandpass filter in the 3G mobile base stations that operates at 1.95 GHz and 60 MHz of bandwidth. The features of 26% smaller-sized and harmonic-suppression have been proposed, and how the harmonics can be suppressed has also demonstrated in this paper

Prospect of 40–170GHz band spherical antenna

In this paper, the feasibility of a spherical antenna has been conducted by simulation. First, a basic model for spherical antenna is made, which consists of a 10 mm-dia sphere and a 600 mm-dia disk. It is shown that the surface current on the sphere is unidirectional, propagating from the feeding point to the zenith. The broadband feature is considered to originate in the nature of traveling wave antenna. Second, the length of the sphere stem, which is extended the coaxial lead to the sphere, is varied, and at 1.4 mm the maximum bandwidth of 5.1-22 GHz. Third, as a recent result the spherical antenna using a thicker stem gives broader bandwidth of 5.2-39.5 GHz. Finally, the structure is reduced by one-eighth, resulting in 40-320 GHz. The radiation pattern in azimuth angle is omnidirectional, and the gain is 3.1 dBi at 50 GHz, 4.9 dBi at 100 GHz and 4.2 dBi at 200 GHz.

Void and Pore Detections by the Scanning Near-Field Millimeter-Wave Microscopic Aperture Probe

To verify the defect on the material may be required for industrial application, such as void and pore detections. In our research, the scanning near-field millimeter-wave microscopy is used to detect the void and pore. In experiment, the voids are formed inside the Teflon sample with various in-depths from 0.5 mm to 10 mm. Each void is 1 mm-dia and 20 mm-length. The air void and water-filled void are recognized at in- depth of 2 mm. Another, the pores are on the surface of the TiO2 sheet with thickness of 2.4 mm. The 0.8 mm-depth pore is clearly recognized. The in-depth capability of void and pore detections has been proposed.

Void Detection in Grout-Filled Sheath Tube by RF Propagation

A grout-filled sheath tube is a key part of prestressed concrete (PC) for strength and durability, and voids in grout endanger PC structures. This paper is to report the initial investigation on void detection by RF reflection through sheath tube. The content includes the results of simulation, void detection experiment on model sheath tube, and measurement of dielectric constant of grout. These results indicate positive evidence.