UWB ANTIPODAL VIVALDI ANTENNA FOR MICROWAVE IMAGING OF CONSTRUCTION MATERIALS AND STRUCTURES

An antipodal Vivaldi antenna (AVA) with ultra-wideband performance is designed for microwave imaging of construction materials and structures. A step-by-step procedure has been employed to design and optimize performance of the proposed antenna. First, conventional AVA (CAVA) is designed. Second, to extend low end of frequency band, the inner edges of the top and bottom radiators of the CAVA have been bent (referred to as AVA-B). Third, to enhance gain at lower frequencies, regular triangular slit is applied to the antenna (referred to as RTSAVA-B). The proposed RTSAVA-B operates at frequency range from 2 to 27 GHz. The proposed RTSAVA-B enhances gain up to 1.5-2 dB. Additionally, it has low cross-polarization< 215 dB at the entire frequency range and capable of improving front-to-back ratio over AVA-B. A prototype of the antenna is fabricated and employed for the imaging of concrete-based specimens. High-range resolution images and high penetration depth inside specimens are achieved. (C) 2017 Wiley Periodicals, Inc.