A 1.3 GHz active phased array antenna for wind profiling boundary layer radar

To prevent weather disaster caused by a downpour and a heavy snowfall, there is growing to need for spatial and automatic improving observation systems in weather conditions. The atmospheric boundary layer radar (BLR) [H. Hashiguchi et al, 1995] is one of wind profiling radars that measure wind directions and velocities from the Doppler shifts of weak reflections (clear-air echoes) along a beam direction. They are widely noticed as ones of meteorological observation instruments. For a parabolic antenna applied as a conventional BLR, there are the following difficulties: First, the beam is fixed, therefore the data acquisition is limited. Second, the antenna is not easy to carry and set up within limited space. In order to relax these issues, we have developed 1.3 GHz active phased array antennas (APAAs) which can achieve electronically beam scanning and easily carriage. These antennas are currently set up at 25 spots in Japan and have been in operation for weather forecast by Japan Meteorological Agency since April 2001 (see Fig. 1). This paper mainly presents the phased array antenna, where electromagnetically coupled coaxial dipole (ECCD) array antennas mounted over a ground plane [H. Miyashita et al., 1999 ]-[Q. Rao et al.] are adapted as radiating elements, for ground based wind profiling in the vicinity of boundary layer and an outline of the BLR system.