Millimeter wave image processor and millimeter wave image processing method
A millimeter wave image processor, capable of performing imaging by matching and filtering while considering a spherical wave on an antenna face in a near field, is provided. The processor includes: a T-antenna which receives a radio wave emitted by a target; an A/D converter which A/D converts signals received by the T-antenna; a correlation processing unit which performs correlation processing to a combination of signals of a horizontal conversion output and a vertical conversion output among A/D converted data; and an imaging processor which correlates a reference function in which a received signal is generated theoretically on an assumption that the target is at a position of a focused distance and a received signal of a spherical wave received by the T-antenna for each pixel in the field of view to thereby create an image of the target.
1. A millimeter wave image processor, comprising:
antennas, arranged two-dimensionally, which receive a radio wave from a target;
an A/D converter which A/D-converts a signal received by the antenna;
a correlation processing unit which performs correlation processing to a combination of A/D-converted data signals; and
an imaging processor which creates an image of the target by correlating an correlation processing output of signals received by the antennas with a reference function, the reference function being a received signal theoretically generated on an assumption that the target is at a position of a focused distance, for each pixel in a field of view.
2. The millimeter wave image processor, according to claim 1 , further comprising, an in-band phase characteristic corrector which performs phase correction to an output of the A/D converter with a transversal filter by a phase correction function previously measured, and makes phase characteristics of vertical and horizontal antennas of a T-antenna coherent.
3. The millimeter wave image processor, according to claim 1 , further comprising, an antenna phase characteristic corrector which compensates phase distortion of a received signal by using an antenna phase distortion correction function generated based on a difference between a phase of an observed value provided by reception processing from a calibration signal generator and a phase of a radio wave of a theoretical value.
4. The millimeter wave image processor, according to claim 1 , wherein as the antennas, a T-antenna in which a plurality of antennas are arranged horizontally and vertically so as to be in T shape is used.
5. The millimeter wave image processor, according to claim 1 , wherein as the antennas, antennas which are linearly moved horizontally and vertically so as to form a T-shaped trajectory to thereby receive a radio wave in a time divisional manner is used.
6. A millimeter wave image processing method, comprising the steps of:
receiving a radio wave from a target;
A/D converting a signal received;
performing correlation processing to a combination of signals of a horizontal conversion output and a vertical conversion output among A/D converted data;
on an assumption that the target is at a position of a focused distance, generating a theoretical received signal as a reference signal for each pixel in a field of view; and
correlating an correlation output between antennas of spherical waves received by a T-antenna with the reference function, and performing matching and filtering steps to generate an image of the target.
7. The millimeter wave image processing method according to claim 6 , comprising the step of forming a T-shaped trajectory by linearly moving multiple sets of antennas horizontally or vertically to thereby receive a radio wave.