Patent ID: 7639173

Claim:
A microwave planar sensor for detecting movement of a target in a detection area, comprising: a microwave board, comprising: an oscillator/mixer layer, comprising an oscillator configured to generate at least one microwave signal and a signal mixer electrically coupled to the oscillator, the signal mixer configured to combine a microwave signal generated by the oscillator and a reflected signal reflected by the target, thereby generating an intermediate frequency signal having a Doppler frequency; an antenna layer, comprising a transmit antenna coupled to the oscillator for transmitting a microwave signal generated by the oscillator into the detection area and a receive antenna coupled to the signal mixer for receiving the reflected signal; and a ground layer disposed between the oscillator/mixer layer and the antenna layer when the oscillator/mixer layer and the antenna layer are bonded together, and a support board, comprising: a top surface bonded to the oscillator/mixer layer of the microwave board through a first metal layer coated on the top surface; and a continuous cavity extending from the top surface for accommodating the oscillator and the mixer of the oscillator/mixer layer, the surface of the cavity coated with a second metal layer.