| 摘要 |
<p>PURPOSE:To prevent the lowering of power of an oscillation signal of non- modulation emitted from an antenna by providing a directional coupler for branching an oscillation signal from an oscillator and connecting an antenna to one output terminal of the directional coupler. CONSTITUTION:The oscillation signal of non-modulation is modulated by the use of a responder in accordance with inherent data and emitted from the antenna of the responder again. The response signal input a mixer 5 is mixed with the oscillation signal from an oscillator 1, so that an IF signal is output and the demodulation of the response signal from the responder thereafter is performed. While the signal output from an output terminal (c) reaches an isolation terminal (d) of the directional coupler 8 through the mixer 5 and a phase regulation means 7, the phase is delayed by n.lambdag+lambdag/4 to output from an output terminal (b). Thereby a signal directly output from the output terminal (b) and another signal output from the output terminal (b) through the output terminal (c), the mixer 5, a phase regulation means 7 and the isolation terminal (d) have the same phase and the lowering of power of the oscillation signal of non-modulation is prevented.</p> |
