| 摘要 |
PURPOSE: To realize a sufficient diversity effect through optimizing adjustment with a simple structure of the antenna circuit of a antenna changeover diversity configuration. CONSTITUTION: A reception level of an envelope detector 7 is compared with a reference level at an input terminal by an envelope comparator 8 and a changeover switch 11 is used to connect an antenna 1 or 2 to a receiver 6. Feeding points 3, 4 of the antennas 1, 2 and a switching point of the changeover switch 11 are connected by a transmission line 10, the impedance of the transmission line 10 matches the impedance of the receiver 6 and the electric length is adjusted to be an integer multiple ofλ/2. Even when the distance between the antennas 1, 2 is at least about 0.5λ, the similar radiation pattern to that of a single unit of each antenna is realized and the diversity effect expected by the single unit characteristic is obtained.
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