Design of UWB Antenna Array for Through-Wall Detection System

In this paper, an ultra-wideband (UWB) antenna array for through-wall microwave imaging (TWMI) system is introduced. The detection system consists of 4-element balanced antipodal Vivaldi antenna array (BAVA) fed by 1-to-4 UWB modified Wilkinson power divider. The antenna element, array, and feed network are optimized, fabricated and tested. The main working principle of the detection system is based on time domain reflectometry (TDR). Wherein, very short pulse generated by the vector network analyzer (VNA) is used to illuminate the wall under investigation through the array system. The exprimental work of scanning a 20 x 20 cm area of two wall separated by 15 cm air gap with the purpose of detecting 4 cm (diameter) metallic ball concealed in a gap between the walls shows a good acuuracy. In order to enhance the resolution of the received image, a special filtering process has been developped and implemented.