METHOD FOR REMOTE DETECTION OF SUBSTANCE Russian patent published in 2013 - IPC G01N24/08 

FIELD: physics.

SUBSTANCE: suspected hiding place of a narcotic drug is subjected to electromagnetic probing with a plane-polarised signal and right- and left-hand circularly polarised signals reflected from the narcotic drug in the concealment environment are received, wherein the reflected right-hand circularly polarised signal is time-gated in proportion to the depth of burial of the narcotic drug, and the reflected left-hand circularly polarised signal is frequency-converted using the frequency w_r1 of a first heterodyne; first voltage at intermediate frequency is selected, and harmonic voltage at stable frequency w_r1 of the first heterodyne is then selected; the phase shift between the reflected right- and left-hand circularly polarised signals at the stable frequency w_r1 of the first heterodyne is then measured; the measured; the measured value of phase shift is compared with a reference value and a decision on presence of a narcotic drug in the concealment environment is made based on the comparison results, wherein the reflected left-hand circularly polarised signal is simultaneously frequency-converted using frequency w_r2 of a second heterodyne.

EFFECT: high noise immunity of the receiving signals and reliability of detecting a substance by suppressing spurious signals received over image and combinational channels.

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