Envelope phase detection for millimetre-wave active imaging

Proposed is an active near-field shape extraction method in millimetre-wave band, namely the envelope phase detection method, where the envelope phase of the amplitude-modulated wave to obtain a three-dimensional shape through phase unwrapping is observed. Distance-to-phase sensitivity appropriate to an objective target size by adjusting the modulation frequency can be chosen. Simultaneously the rectilinear propagation nature of millimetre-wave can be preserved, and there is no need for aperture synthesis, which leads to reduction of calculation time. Harmful glare, which sometimes occurs in active millimetre imaging, is mitigated so effectively that the shape of an object appears more clearly. In addition, the simple receiver construction is compatible with array receiver antennas and parallel processing for real-time imaging.