METHOD AND SYSTEM FOR MILLIMETER-WAVE IMAGE RECONSTRUCTION

• US 20150293221A1
• Filed: 04/10/2015
• Published: 10/15/2015
• Est. Priority Date: 04/14/2014
• Status: Active Grant

• Current Assignee: Rohde & Schwarz GmbH & Company KG
• Original Assignee: Rohde & Schwarz GmbH & Company KG
• Inventors: Ahmed, Sherif Sayed
• Granted Patent: US 10,330,785 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/02 Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques

Abstract

The invention relates to a technique for millimeter-wave active image reconstruction. According to a method aspect, Tx subgroups of transmitting antennas of an antenna array are established. Coherent processing of measurement data is performed for each Tx subgroup and coherent subimages are achieved. Magnitudes of complex numbers are calculated to obtain a magnitude subimage for each of the coherent subimages and an object image is generated by adding the magnitude subimages.

Claims

1. A method for reconstructing an image of an object, comprising the steps of:

illuminating the object by transmitting millimeter-wave and/or micrometer-wave radiation from an array of transmitting antennas;

detecting signals of radiation reflected by the object with an array of receiving antennas and representing the detected signals by complex-numbered measurement data;

performing coherent processing of the measurement data including complex number computations for image reconstruction;

establishing Tx subgroups of transmitting antennas for which coherent processing is performed to achieve coherent, subimages; and

calculating magnitude values each indicative of a magnitude of a complex number to obtain a magnitude subimage for each of the coherent subimages and generating the object, image by adding the magnitude subimages.

2. The method according to claim 1,

whereby the Tx subgroups are sequentially measured such that each Tx subgroup is measured in a single, contiguous, non-overlapping time period.

3. The method according to claim 1,

whereby the steps of establishing for each Tx subgroup a specific Rx subgroup of receiving antennas contribute to achieve the coherent subimage of the corresponding Tx subgroup.

4. The method according to claim 1,

whereby the steps of providing phase values of the coherent subimages for estimating comprise phase values for the object image.

5. A system for reconstructing an image of an object, comprising

an array of transmitting antennas adapted to illuminate the object by transmitting millimeter-wave and/or micrometer-wave radiation;

an array of receiving antennas adapted to detect signals of radiation reflected by the object;

at least one component adapted to represent the detected signals by complex-numbered measurement data;

at least one component adapted to perform coherent processing of the measurement data including complex number computations for image reconstruction;

at least one component adapted to establish Tx subgroups of transmitting antennas for which coherent processing Is performed to achieve coherent subimages; and

at least one component adapted to calculate magnitude values each indicative of a magnitude, of a complex number to obtain a magnitude subimage for each of the coherent subimages and to generate the object image by adding the magnitude subimages.

6. The system according to claim 5,

wherein the Tx subgroups comprise each one and the same number of transmitting antennas.

7. The system according to claim 5,

wherein the Tx subgroups comprise mirrored transmitting antennas.

8. The system according to claim 5,

wherein in case a Tx subgroup has an associated Rx subgroup, the number of receiving antennas of the Rx subgroup is at least the number of antennas of the associated Tx subgroup.

9. The system according to claim 8,

wherein effective apertures of Tx subgroups and associated Rx subgroups fully cover an aperture of the transmitting antenna array and/or the receiving antenna array.

10. The system according to claim 5,

wherein multiple Rx antenna clusters comprise each a plurality of the receiving antennas and further comprising each a processing module for performing at least a part of the coherent processing.

11. The system according to claim 10,

wherein a central processing unit is adapted to perform the remaining of the coherent processing, and to establish the object image.

12. The system according to claim 11,

wherein the Rx antenna cluster is adapted to perform coherent processing to generate an intermediate image for a Tx subgroup,

and wherein the central processing unit is adapted to perform a coherent processing including complex adding of multiple intermediate images to generate the coherent subimages.

13. The system according to claim 12,

wherein the central processing unit Is adapted to perform at least one of an image interpolation and an incoherent addition of the coherent subimages.

14. The system according to claim 5,

wherein the system comprises tracking sensor equipment for relative positioning of the magnitude images before adding and/or volume limiting intermediate images.

15. A computer program comprising program code portions for performing the steps of:

illuminating the object by transmitting millimeter-wave and/or micrometer-wave radiation from an array of transmitting antennas,

detecting signals of radiation reflected by the object with an array of receiving antennas and representing the detected signals by complex-numbered measurement data;

performing coherent processing of the measurement data including complex, number computations for image reconstruct ion;

establishing Tx subgroups of transmitting antennas for which coherent processing is performed to achieve coherent subimages; and

calculating magnitude values each indicative of a magnitude of a complex number to obtain a magnitude subimage for each of the coherent subimages and generating the object image by adding the magnitude subimages.