Progress In Electromagnetics Research C, Vol. 124, 81–96, 2022 Development of an IR-UWB Radar System for High-Resolution Through-Wall Imaging Mohamed Saad 1, * , Abdelmadjid Maali 1 , Mohamed S. Azzaz 1 , Azzedine Bouaraba 2 , and Mustapha Benssalah 3 Abstract—Through-Wall-Imaging (TWI) radar offers considerable advantages for applications that require safety and security, such as disaster survivor rescue and tracking terrorist activities. In such situations, the use of an impulse UWB radar system is constantly increasing due to its ability to provide precise images of hidden targets in a short period of time. This paper presents a new radar system for through-wall imaging using an impulse-radio ultra-wideband (IR-UWB) signal. The radar system is built using a field-programmable gate array (FPGA) board, an oscilloscope, and Vivaldi antennas. The radar system transmits impulse signals, which have a monocycle shape with a 400-picosecond duration and a 4.6 GHz bandwidth. The FPGA board is used to produce impulse signals that have a short time duration in the sub-nanosecond range in order to expand the bandwidth of the generated signal and make the developed radar capable of providing high-resolution images. The FPGA-based implementation of the IR-UWB generator offers the flexibility to modify the spectrum characteristics of the generated signal. The receiver side of the radar system collects the echoes using the principle of synthetic aperture radar (SAR), and then the time-domain back-projection algorithm is applied to the radar echo to form 2D images. An indoor imaging experiment was carried out with two human targets to investigate the imaging capability of the designed IR-UWB radar. The obtained experimental results demonstrate that this radar has the potential to deliver high-resolution images of multiple human targets and identify their locations. 1. INTRODUCTION Through-the-wall imaging radar has the ability to image targets located behind opaque material, such as a wall and door. This capability is desirable in many situations that require safety and security, such as rescue missions and tracking terrorist activities [1]. Ultra-wideband (UWB) signals are extensively used in radar systems for through-obstacle-imaging applications such as through-the-wall imaging radar [2], ground penetration radar (GPR) [3], and medical imaging radar [4]. Due to their ability to provide high-resolution images, when a UWB signal is used, the radar tends to achieve centimeter resolution. In addition, UWB signal has better penetration capacity through materials [5]. The most frequently employed UWB signals are: frequency modulated continuous wave (FMCW) signal [6], stepped frequency continuous wave (SFCW) signal [7], and Impulse IR-UWB signal [8]. Typically, the radar systems that employ CW signals have a simple radar architecture and good target detection abilities [9]. However, the processing time of these radar systems is relatively slow compared to IR-UWB radars for the following reasons. First, IR-UWB radar has the ability to instantly illuminate the scene with a UWB signal, by generating pulses that have an Received 2 June 2022, Accepted 30 August 2022, Scheduled 16 September 2022 * Corresponding author: Mohamed Saad (saad.mohamed.ts@gmail.com). 1 Laboratoire Syst` emes ´ Electroniques et Num´ eriques, ´ Ecole Militaire Polytechnique, BP 17 Bordj El-Bahri, Algiers, Algeria. 2 Laboratoire Radar, ´ Ecole Militaire Polytechnique, BP 17 Bordj El-Bahri,Algiers, Algeria. 3 Laboratoire Traitement du Signal, ´ Ecole Militaire Polytechnique, BP 17 Bordj El-Bahri, Algiers, Algeria.