Development of a millimetre wave based SAR real-time imaging system for three-dimensional non-destructive testing

Abstract

The following article describes the development of a millimetre wave based real-time imaging system for three dimensional non-destructive testing of goods. For this purpose a rotating antenna is used which is fed from an FMCW radar. The received measuring data is processed with a SAR algorithm. Due to the fact that a reflexive measurement method is used, the integration of the system into existing systems is simplified. To make the computing power-intensive SAR image processing possible, the complete signal processing chain of the image processing is executed on the graphics card. The article elucidates the concept for calculating the measurement parameters which have to be elaborated for the implementation of the image processing of the whole system.

Inline Inspection of Packaged Food Using Microwave/Terahertz Sensing—An Overview with Focus on Confectionery Products

“…Finally, the cost of THz-based inspection systems is also a critical issue limiting their dissemination, which has been highlighted in numerous works [8,18,21]. Microwave-based devices using low-cost PCBs [34] or SAR methods [40] are more compact and cheaper than gyrotron systems due to lower manufacturing costs for the low-cost highly-integrated ICs and materials, lower operating costs (gyrotrons require high power to build up the magnetic field or maintain active cooling) and lower technological complexity.…”

“…A series of comparatively low-cost, low-powered prototypes (called SAMMI), which are capable of real-time using millimetre waves (M-band) have been iteratively developed by Demming et al [39], Küter et al [31], and Schwäbig et al [40]. Vertically positioned and collinearly aligned transmit and receive antennas that mounted on mechanically rotating discs operating at 78 GHz were used by Demming et al, while sample is moved between them using a conveyor belt during the measurement (see Figure 4a).…”

“…Schwäbig et al [40] extended the abilities of SAMMI (see Section 4.1) to resolve a three-dimensional (voxel-based) permittivity distribution using an efficient FMCW-based SAR. Due to novel approach, the mechanical setup was modified, where the transmit and receive antenna were placed both on the upper rotary disk (see Figure 5).…”