| 摘要 |
<p>PURPOSE:To enable an obstacle for an aircraft which is located on or near an approach surface at an airport to be found previously by radiating a first beam at an elevation which matches an approach angle of the aircraft and at the same time radiating a second beam onto a ground surface at an elevation of 0. CONSTITUTION:A circulator 12 outputs a transmission energy from a transmitter 11 to an antenna 10. The antenna 10 is wide in vertical direction, radiates an antenna beam with a small angle width in a direction of azimuth angle, receives an echo from a target, and then outputs a second reception signal. An antenna 14 is narrow in vertical direction, radiates an antenna beam with a large angle width in the direction of azimuth angle, receives the echo from the target object, and then outputs a first reception signal. A receiver 15 receives the second reception signal and outputs an output signal B which indicates that the target exists when a signal intensity where an aircraft signal is eliminated exceeds a specified level. A receiver 16 outputs an output signal A which indicates that the target exists when a reception signal intensity from the antenna 14 exceeds a specified level. An obstacle-discriminating portion 20 judges an obstacle according to the signals A and B, thus enabling a danger to be indicated.</p> |
