| 摘要 |
PURPOSE:To eliminate the influence of an unnecessary reflected wave or interfering wave and to measure accurate distance by equipping a specific body with a special passive reflecting element for a system which measure the distance to the specific body by using a radio wave. CONSTITUTION:The rotation tablet 7 consisting of half-wavelength antennas 1a and 1b is fitted to a target 6 as an object of distance measurement. On the other hand, a radio wave transmitter-receiver is provided to a fixed station 9. A transmit wave from an oscillator 10 is sent toward the target 6 through an antenna 16. The radio wave arriving at the target 6 is reflected by the tablet which rotates at an angular frequency OMEGA and received by the antenna 16 of the fixed station 9. This receive wave passes through a phase shifter 17 and is mixed with part of the transmit wave passed through a demultiplexer 11 by a directional coupler 12 and a mixer 13 to perform synchronous detection. The center frequency of a band-pass filter 18 coincides with the angular frequency of the tablet 7, so the phase shifter 17 and a transmission frequency are adjusted so that the output of the filter is zero, thereby calculating the distance to the target from the relation. |
