Antipodal Vivaldi antenna with improved radiation characteristics for civil engineering applications

An ultra-wideband elliptically tapered antipodal Vivaldi antenna designed for civil engineering applications is presented. It is based on design of a conventional antipodal Vivaldi antenna (CAVA) which impedance bandwidth is limited at low end of frequency band. To extend impedance bandwidth, inner edges of top and bottom radiators of the CAVA have been properly bent; however, its gain and front-to-back (F-to-B) ratio is low at the low frequencies. To enhance gain and F-to-B ratio, the comb-shaped slits on edges of the radiators of CAVA are applied. The obtained results exhibit the impedance bandwidth of 1.65-18 GHz, gain of 6.7 dB at 1.65 GHz, and F-to-B ratio of 42 dB at 13.5 GHz that are higher than those parameters of the CAVA. Applicability of the proposed antenna for detection of void inside concrete beam is demonstrated. First, models of the proposed antenna and concrete beam possessing void are created in computer simulation technology and numerical study is performed. Then, a prototype of the antenna is fabricated and employed as part of microwave imaging system to verify simulation results and to detect voids inside concrete beam.