A Novel 24 GHz One-Shot, Rapid and Portable Microwave Imaging System

Development of microwave and millimeter wave imaging systems has received significant attention in the past decade. Signals at these frequencies penetrate inside of dielectric materials and have relatively small wavelengths. Thus. imaging systems at these frequencies can produce images of the dielectric and geometrical distributions of objects. Although there are many different approaches for imaging at these frequencies. they each have their respective advantageous and limiting features (hardware. reconstruction algorithms). One method involves electronically scanning a given spatial domain while recording the coherent scattered field distribution from an object. Consequently. different reconstruction or imaging techniques may be used to produce an image (dielectric distribution and geometrical features) of the object. The ability to perform this accurate~v and fast can lead to the development of a rapid imaging system that can be used in the same manner as a video camera. This paper describes the design of such a system. operating at 2-1 GHz. using modulated scatterer technique applied to 30 resonant slots in a prescribed measurement domain

A Real-Time Microwave Camera at 24 GHz (K-Band}

The objective is to design and build a real-time microwave imaging system (i.e., camera) Microwave imaging offers tremendous potential in many applications: a) Inspection of low-loss composites, radomes, etc.; b) Detection and evaluation of corrosion under paint; c) Security, contraband detection. Raster scanning is slow and requires bulky mechanical systems. A real-time and portable imaging system can be extremely useful for rapid nondestructive testing of large structures

A Real-Time Microwave Camera at K-Band (24 GHz)

Nondestructive testing (NDT) community has been moving towards effective and robust inspection systems that can provide real-time information about materials, geometrical, structural and mechanical characteristics of composite materials/structures. Moreover, in many applications it is desired to have an image of the structure, after which the information contained in the image is correlated to the above characteristics. Microwave signals penetrate inside of dielectric composite structures and their interaction with the interior of the structure renders critical information for NDT purposes. Subsequently, this information (i.e., magnitude and phase or reflected signal) may be used to produce an image of the interior of the structure revealing potential flaws or anomalies. Image processing and reconstruction techniques may also be incorporated to produce high-resolution images (i.e., synthetic-aperture, back-propagation, etc.). There are several different approaches for designing areal-time microwave camera system. One approach is based on modulated scatterer technique (MST), which is used to tag scattered electric field in a discrete two-dimensional (2D) spatial domain (e.g. a retina) resulting in the 2D magnitude and phase distribution of the scattered electric field which is required for producing an image of a material or structure under inspection. The ability to rapidly modulate resonant slot antennas in such a retina along with using receivers with fast responses provide for real-time image production capability. Design issue and criteria become more challenging at higher frequencies and for a relatively large retina size. This paper presents the basic design and challenges for a microwave camera with a retina size of 6" by 6" operating at a frequency of 24 GHz

Millimeter wave imaging as a tool for traceability and identification of tattooed markers in leather

In this work, an innovative solution for traceability of leather throughout the leather manufacturing process is presented. The proposed solution is founded on the use of high-resolution millimeter wave synthetic aperture radar (SAR) imaging technique that can be effectively used to sense the presence of sub-surface identification markers inserted (tattooed) into the hides to be tracked. This proposed imaging solution satisfies all the major requirements of the considered applications; in fact, the identification markers do not affect the characteristics of the finished leather product. The proposed imaging system is also completely noninvasive, and fully scalable for industrial applications. For validating the proposed technique, different leather samples were tattooed with conductive ink, and the presence of the markers was then sensed through SAR millimeter wave images. For comparison purposes, several X-ray scans were also obtained from the leather samples

UWB Microwave Imaging Array for Nondestructive Testing Applications

This paper presents the design of a switched ultrawideband (UWB) microwave imaging array. The imaging array is designed as an interlaced bi-static transmit and receive array in order to provide optimal coverage of the sample being imaged. The array utilizes wideband Vivaldi antennas as the array elements. The array is designed for optimal spacing between its elements to satisfy the requirements of synthetic aperture imaging. The calibration procedure and utility of this array is presented

Millimeter Wave Synthetic Aperture Imaging System with a Unique Rotary Scanning System

This is the video that accompanies the "Millimeter Wave Synthetic Aperture Imaging System with a Unique Rotary Scanning System" presentation. It shows the operation of the scanning system, and reviews the results of the scanning of a sample

Fusion of microwave and eddy current data for a multi-modal approach in evaluating corrosion under paint and in lap joints

Critical aircraft structures are susceptible to hidden corrosion. Find-it and fix-it approaches are inefficient as it relates to managing the problems associated with corrosion. More comprehensive corrosion information may be obtained using data fusion from several detection and evaluation methods. To this end, microwave, conventional and pulsed eddy current data from a multi-layer corroded panel, representing an aircraft lap joint, are fused and used as inputs to a structural analysis model to obtain a comprehensive snapshot of the corroded environment. This paper presents the data fusion algorithm and the structural analysis model along with a discussion of the results