| 摘要 |
PROBLEM TO BE SOLVED: To provide a diversity antenna apparatus, capable of being placed in a narrow space and surely reducing drop of reception electric field due to fading. SOLUTION: Whip antennas 21 and 22 are mounted on the roof of train 30 in a fore-and-aft direction atλ/8 to 1.6λ/8 intervals. A directivity control part 31 is composed of three-way distributors 32 and 33 and two-way distributors 34-36, and the control part 31 connects feeding points of the whip antenna 21 and 22 with the distributors 34-36 via the distributors 32 and 33. The distributors 34 and 35 distribute a signal in two ways with phase 0°and -60°, respectively, and the distributor 36 distributes the signal in two ways with the same phase (0°), respectively. External connection terminals of the distributors 34 and 35 are connected with a radio communication device as beam terminals 37 and 38 respectively, and the external connecting terminal of the distributor 36 is connected with the communication device as a omnidirectional terminal 39. The communication device selects the beam terminals 37, 38 and the omnidirectional terminal 39, in response to receiving conditions and conducts diversity reception. COPYRIGHT: (C)2003,JPO
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