Radar device and method of measuring distance and reflecting factor

A radar device comprising:

• a transmitting antenna for transmitting sine-wave radio wave towards a target,
• a receiving antenna for receiving radio wave reflected from the target,
• a first wave-detecting circuit for multiplying radio wave voltage being transmitted from the transmitting antenna by radio wave voltage being received by the receiving antenna,
• a shifting means for causing ¼ period phase shift in either the radio wave being transmitted or the radio wave being received, and
• a second wave-detecting circuit for multiplying radio wave voltage being transmitted from the transmitting antenna by radio wave voltage shifted by the shifting means from the radio wave being received by the receiving antenna, or multiplying radio wave voltage shifted by the shifting means from the radio wave being transmitted from the transmitting antenna by radio wave voltage being received by the receiving antenna;
• wherein the shifting means comprises a second receiving antenna, the second receiving antenna being located at a position separated from the receiving antenna by a distance ¼ of the radio wave wavelength in addition to distance of an integer multiple of the radio wave wavelength at a further side of the receiving antenna from the target, whereby the radio wave received by the second receiving antenna has ¼ period phase shift behind the radio wave received by the receiving antenna.

A radar device comprising:

• a transmitting antenna for transmitting sine-wave radio wave towards a target,
• a receiving antenna for receiving radio wave reflected from the target,
• a first wave-detecting circuit for multiplying radio wave voltage being transmitted from the transmitting antenna by radio wave voltage being received by the receiving antenna,
• a shifting means for causing ¼ period phase shift in either the radio wave being transmitted or the radio wave being received,
• a second wave-detecting circuit for multiplying radio wave voltage being transmitted from the transmitting antenna by radio wave voltage shifted by the shifting means from the radio wave being received by the receiving antenna, or multiplying radio wave voltage shifted by the shifting means from the radio wave being transmitted from the transmitting antenna by radio wave voltage being received by the receiving antenna,
• a switching means, the switching means being selectable between a first state and a second state;
• wherein hardware of the first wave-detecting circuit and the second wave-detecting circuit comprises a common wave-detecting circuit,
• in the first state, the radio wave being transmitted and the radio wave being received are input to the common wave-detecting circuit, and
• in the second state, the radio wave voltage being transmitted and the radio wave shifted by the shifting means from the radio wave being received, or the radio wave shifted by the shifting means from the radio wave being transmitted and the radio wave being received are input to the common wave-detecting circuit.

A radar device comprises:

• a transmitting antenna for transmitting sine-wave radio wave towards a target,
• a receiving antenna for receiving radio wave reflected from the target,
• a first wave-detecting circuit and a second wave-detecting circuit for multiplying the radio wave voltage transmitted from the transmitting antenna by the radio wave voltage received by the receiving antenna, and
• a shifting means causing ¼ period phase shift between Δp1 and Δp2, wherein Δp1 is phase difference between the transmitted radio wave and received radio wave multiplied by the first wave-detecting circuit, and Δp2 is phase difference between the transmitted radio wave and received radio wave multiplied by the second wave-detecting circuit.

A method of measuring distance to a target, the method comprises:

• a step of transmitting sine-wave radio wave towards the target,
• a step of receiving radio wave reflected from the target,
• a first wave-detecting step of multiplying radio wave voltage transmitted by radio wave voltage received,
• a second wave-detecting step of multiplying radio wave voltage transmitted by the radio wave voltage received,
• a shifting step of causing ¼ period phase shift between Δp1 and Δp2, wherein Δp1 is phase difference between the transmitted radio wave and received radio wave multiplied in first wave-detecting step, and Δp2 is phase difference between the transmitted radio wave and received radio wave multiplied in the second wave-detecting step, and
• a step of calculating the distance to the target on the basis of the ratio of the output voltage obtained by the first wave-detecting step and the output voltage obtained by the second wave-detecting process.

A method of measuring radio wave reflecting factor of a target, the method comprises:

• a step of transmitting sine-wave radio wave towards the target,
• a step of receiving radio wave reflected from the target,
• a first wave-detecting step of multiplying radio wave voltage transmitted by radio wave voltage received,
• a second wave-detecting step of multiplying radio wave voltage transmitted by radio wave voltage received,
• a shifting step of causing ¼ period phase shift between Δp1 and Δp2, wherein Δp1 is phase difference between the transmitted radio wave and received radio multiplied in the first wave-detecting step, and Δp2 is phase difference between the transmitted radio wave and received radio wave multiplied in the second wave-detecting step, and
• a step of calculating reflecting factor of the target on the basis of the sum of the square of the output voltage obtained by the first wave-detecting step and the square of the output voltage obtained by the second wave-detecting step.