Katsuyuki Imai

Development and Initial Observation of High-Resolution Volume-Scanning Radar for Meteorological Application

A new high-resolution Doppler radar, called Ku-band broadband radar (BBR), with fast scanning capability for meteorological application has been developed. Due to the new system design, the BBR can accurately measure the radar reflectivity factor with a range resolution of several meters and a time resolution of 55 s per volume scan from the nearest range of 50 m to 15 km for 10-W power using pulse compression. In this paper, the basic concepts, configuration, and signal processing of the BBR are described. In the initial observation, the observation accuracy of reflectivity is evaluated using Joss-Waldvogel disdrometer (JWD). As a result, the reflectivity of the BBR is in fairly good agreement with that of JWD. In addition, in the spiral observation, a fine structure of a thunderstorm obtained by the BBR is presented.

Rainfall observation with high resolution using Ku-band broad band radar

A new high resolution Doppler radar, the Ku-band broad band radar, with scanning capability for meteorological application has been developed. Due to the new system design, the BBR can accurately measure the radar reflectivity factor with the range resolution of 5 m and the time resolution of 1 min per 1 volume scan from the nearest range of 50 m to 15 km for 10 W power using pulse compression. In this paper, the brief description of the BBR and the initial observation results are shown. In the calibration, reflectivity factor of the BBR is fairly good agreement with the Joss-Waldvogel disdrometer. In the volume scanning observation, we succeeded to detect fine 3 dimensional structures of precipitation.

Unique attenuation characteristics of ku-band Lune-Q antenna for Satellite retransmission of terrestrial digital broadcasting signal

This paper deals with the unique low rain attenuation characteristics of the Lune-Q antenna, which is used in the satellite retransmission system for terrestrial digital broadcasting CTV signal by using the 14/12 GHz band transponder. To achieve the optimum design of the satellite retransmission system of terrestrial CTV signal, propagation experiments to determine the propagation characteristics and confirm the satellite digital broadcasting CTV transmissions service quality confirmation were carried out in 2006, between the JSAT Yokohama Satellite supervisory and control station (JSAT-ES) and Hokkaido Institute of Technology (HIT) earth-station (HIT-ES). During the propagation experiments, it was found that the Lune-Q antenna rain attenuation characteristics are superior to those of the conventional parabolic antenna, i.e., small rain attenuation values. The rain attenuation values of conventional parabolic antenna and the Lune-Q antenna were compared, for the period from April to October 2006. It can be observed that rain attenuation values of the Lune-Q antenna were about 1/10 times lower. The small rain attenuation characteristics are considered to originate due to reasons such as multi-path reception by the Lune-Q lens characteristics, the feed horn position, and polarization effects, etc.