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Stratospheric [O.sub.3] and ClO were simultaneously observed off the northeastern coast of Japan by the Balloon-Borne Superconducting Submillimeter-Wave Limb-Emission Sounder (BSMILES) developed at National Institute of Information and Communications Technology. BSMILES is a highly sensitive submillimeter radiometer that exploits the superconductor-insulator-superconductor (SIS) technology for atmospheric research. This paper presents the first BSMILES spectra, and describes the details of the calibration process. The vertical profiles of [O.sub.3] and ClO have been also retrieved. In spite of some calibration uncertainties the obtained profiles are in relatively good agreement with previous and other available measurements. Index Terms--Balloon-borne observation, limb sounder, microwave spectroscopy, retrieval of atmospheric profile, stratospheric chemistry, submillimeter wave, superconducting receiver. more...

In the first half of this paper, an efficient method to calculate transmission and reflection characteristics of wire-grids consisting of periodic arrays of cylindrical conductors for arbitrary directions of incidence is presented by extending exact theory of wire-grids proposed by Yasumoto et al. In the latter half of this paper, an approximate calculation method for wire-grids with slight random irregularity in their spacings between wires is proposed by treating the irregularity as a small perturbation to the theory for regular grids. A comparison with preliminary measurements for actual wire-grids in millimeter- and submillimeter-wave regions demonstrated that this method is effectively applicable to wire-grids whose irregularity is not too much. Index Terms--Electromagnetic reflection, electromagnetic scattering by periodic structures, submillimeter wave devices, submillimeter wave measurements, wire grids. more...

This paper presents a new configuration of quasi-optical polarization-rotating dual-beam interferometer, which uses a pair of frequency-selective polarizers (FSPs) consisting of a wire-grid placed in front of a flat mirror, and has a function similar to the conventional Martin-Puplett interferometer (MPI). Advantages of this new configuration over the conventional MPI are lower residual reflection at the input and output ports and suitability to fixed-tuned applications. An experiment has shown it to have an MPI-like frequency characteristic as calculated. Careful machining was successful in achieving accuracy needed for a specified filter characteristic. This FSP-based quasi-optical device is to be used as a sideband separator in a space-borne submillimeter receiver for atmospheric research. Index Terms--Martin-Puplett interferometers (MPIs), polarization-rotating dual-beam interferometers, quasi-optical filters, sideband separators. more...

Laboratory measurements of a backscattered signal for large spherical scatterers are performed to investigate the range of applicability of approximate theory, which we used in interpreting the measured depolarization signatures of rain. The measured linear depolarization ratios (LDR's) are in remarkably good agreement with theoretical calculations. more...

The complex refractive index of concrete is measured at 57.5 GHz by the combined use of free-space reflection and transmission methods. The measured refractive index of the concrete 14 months after concreting was 2.55 - j0.084. This index, in particular the imaginary part, is sensitive to the curing time after concreting and the water content. The transmission coefficient of a concrete plate, mainly determined from the imaginary part of the complex refractive index, is less than -20 dB/cm when the concrete is fresh and moist and reaches -9 dB/cm after aging for fourteen months. In contrast, the reflection coefficient of a concrete plate is less dependent on water content. more...

Measurements of polarization dependence of multipath-propagation characteristics were conducted at 60 GHz in a room within a modern office building. Delay profiles were measured using a swept frequency method with a high time-delay resolution of 2 ns. Directions of arrival of the multipath components reflected from walls were analyzed by rotating a narrow-beam receiving antenna with an angular resolution of 5 degrees. Results of this experiment showed that multipath delayed waves due to wall reflection can be effectively suppressed by employing circular polarization instead of linear polarization. Based on this experimental result, a computer simulation was made to clarify the polarization dependence of the high-speed transmission characteristics of an indoor communications system operating at 60 GHz. more...

A switchable multi-sector antenna for indoor wireless local-area network (LAN) systems in the 60-GHz band has been proposed. The antenna has a pyramidal configuration. Each isosceles-triangular surface of the pyramid has been inclined 30[degrees] from the vertical axis in order to cover an appropriate elevation angle range. This antenna excites a right-handed circularly polarized wave to suppress unwanted multipath delayed waves. The low-loss curved microstrip-line feeding has been introduced at the junction between antenna feed lines and monolithic microwave integrated circuit (MMIC) amplifiers at the bottoms of the pyramid. Using this antenna, the terminal receiver for indoor wireless LAN systems in the 60-GHz band has been developed. Index Terms - Curved micro, trip lines, millimeter-wave LAN's, multi-sector antenna, patch antennas. more...