Toshio Nemoto

Automatic Calorimeter System for the Effective Efficiency Measurement of a Bolometer Mount in 35-GHz Band

An automated calorimetric measurement system using a microcomputer has been developed for determining the effective efficiency of a bolometer mount in the millimeter-wave region. This system consists of a calorimetric measurement part, a bolometric measurement part, and a control/data processing part. The system has been constructed and experimented in 35-GHz band. The accuracy of the system has been estimated within ±0.37 percent.

A Thin-Film Bolometer Unit

The bolometer unit widely used for measuring microwave and millimeter wave power becomes more difficult to construct and obtain good performance, as the wavelength gets shorter. To overcome these difficulties, a new unit has been developed which has a very simple structure by virtue of a new matching procedure. The bolometer element is made of a thin metal film evaporated on a thin mica substrate, and its mount consists only of a short circuit and a flange. Experimental units have been designed at 35 GHz and 10 GHz, and these have demonstrated excellent characteristics, such as high efficiency, low VSWR, wide bandwidth, high power handing capacity, etc. The thermistor units applying the same matching theory are also investigated at 35 GHz and 50 GHz.

Newly Developed Bolometer Mounts for the Short Millimeter Wave Region

Two kinds of bolometer mounts have been recently developed at the Electrotechnical Laboratory (ETL) that are suitable for the millimeter wave region, especially for the short millimeter waves. They are 1) a matched-load-type bolometer mount and 2) a rising-sun-type bolometer mount. The former is the mount for measuring the rectangular waveguide power and the latter is for the circular TE01 mode waveguide power. Experimental mounts of both kinds have been designed and examined at 100 GHz. These mounts have demonstrated superior performance compared to those commercially available.

Determination of the quantized hall resistance value by using a calculable capacitor at ETL

We report the International System (SI) value of the quantized Hall resistance (R<inf>H</inf>) determined by using a calculable capacitor at the electrotechnical laboratory (ETL). As the result of our measurements at ETL, a most reliable value of h / e² has been estimated as 25 812.8036 Ω<inf>SI</inf> with a systematic uncertainty of 0.25 ppm root sum square (rss) and a random error of 0.20 ppm one standard deviation (1σ).

A Matched-Load Type PVF2 Pyroelectric Detector for Millimeter Waves

A practical pyroelectric detector for rectangular waveguide at 100 GHz has been constructed. This detector has the matched-load type structure and employs PVF2 as the pyroelectric material. The noise equivalent power of 8 nW/¿Hz has been obtained.

A Binary Phase-Modulation Technique of Measuring Microwave Phase Shift

A precision measurement system for the differential phase shift of a two-port device has been developed. The system is based on a two-channel circuit of which the phase of one channel is shifted 90° back and forth periodically. The response of the system is essentially independent on an amplitude change which is usually accompanied by the phase shift of the two-port device. An X-band measurement system has been constructed and examined. It is proved that the system has 0.02° resolution in phase angle. This system is also applied for the precise attenuation measurement by using a similar technique to the modulated subcarrier technique.

A Homodyne Detection at 100 GHz with a Pyroelectric Detector

Homodyne detection of 100-GHz signals has been accomplished with a PVF2 pyroelectric detector. The minimum detectable power was 4 X 10-15 W using approximately 1-Hz bandwidth. The technique is applicable to active measurements where the signal source can be used as the local oscillator of the homodyne detection.