Microwave and Millimetre Wave Antipodal Vivaldi Antenna with Periodic Slit-Edge Technique and the Trapezoid-Shaped Dielectric Lens for Imaging of Concrete-Based Composite Materials

Abstract

A compact antipodal Vivaldi antenna (AVA) with high gain at low frequencies and front-to-back ratio, lower operating frequency (3.4 GHz) and wide operating bandwidth from 3.4 to 40 GHz is presented in this chapter. It includes periodic slit-edge technique and trapezoid-shaped dielectric lens as an extension of substrate. Applicability of the proposed AVA for UWB imaging of construction materials and structures for non-destructive testing and evaluation is demonstrated using three different samples including a concrete block with plasterboard sheets to highlight the high-range resolution of the proposed antenna. In the first sample, capability of the proposed antenna for the detection and evaluation of targets such as metal discs placed at different heights on foam substrate is demonstrated. In the second sample, a practical sample that is based on cubic concrete block was prepared and imaged. A groove was made on the top surface of the block and one steel rod was inserted in the groove. In the third sample, top of the cubic concrete block was covered by plasterboard sheets and an air gap was created by removing one sheet. Third sample had a cavity in a composite structure and imaging results are provided.