Development of a High-Sensitivity Millimeter-Wave Radar Imaging System for Non-Destructive Testing

Area of Science:

• Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Urgent need for non-destructive testing (NDT) methods for infrastructure and residences to prevent collapse.
• Desire for remote, non-contact inspection methods with high sensitivity for small cracks and internal damage.
• Ensuring engineer safety during structural inspections is paramount.

Purpose of the Study:

• To develop a highly sensitive, remote, non-contact NDT system for infrastructure.
• To create a millimeter-wave (MM-wave) synthetic aperture radar (SAR) imaging system.
• To detect surface cracks as small as 0.1 mm and internal structural defects.

Main Methods:

• Developed a radar module with high directivity and minimal signal loss.
• Implemented a single-input, multiple-output (SIMO) synthetic aperture radar (SAR) imaging system.
• Conducted performance evaluations, including SNR improvement and penetration depth measurements in concrete.

Main Results:

• Achieved a 5.4 dB SNR improvement in MM-wave imaging compared to previous systems.
• Successfully detected 0.1 mm cracks in concrete hidden under paint and tape from 3 meters.
• Determined the MM-wave attenuation distance in a 3.7 mm concrete slab to be 6.0 mm.

Conclusions:

• The developed SIMO-SAR system meets the stringent requirements for remote, non-destructive infrastructure inspection.
• The system demonstrates high sensitivity in detecting small surface cracks and internal defects in various construction materials.
• This technology enhances safety and reliability in assessing the condition of critical structures.