Microwave Imaging With Novel Time-Domain Clutter Removal Algorithm Using High Gain Antennas for Concealed Object Detections

Abstract

This paper presents a novel time-domain clutter removal algorithm for microwave imaging of concealed objects using a new high gain ultra-wideband (UWB) antipodal antenna. Bistatic antenna setup is employed to image the objects like a gun prototype, knife and blade using UWB Gaussian modulated pulses. A synthetic aperture radar (SAR) beamforming algorithm with a new clutter removal method is adopted for microwave imaging of the objects inside and outside the anechoic chamber. The proposed algorithm successfully removes the unwanted clutter from the measured scanning data, with only single scanning of the target area. The proposed method along with windowing, envelope detection and finally image reconstruction results in effective reconstruction of the concealed target as compared to the existing methods in the literature. An UWB high gain antipodal antenna is designed for the proposed imaging setup with a peak gain of 26 dBi at 8.4 GHz, which is the highest among previously reported UWB antennas. The proposed antenna achieves a wide gain bandwidth over 6 – 14 GHz (80%) with a gain of > 18 dBi. Simulation and measured results validate the design principle of the antenna with characteristics like high front to back ratio, narrow half-power beam width, and low cross-polarization. In the opinion of the authors, the proposed clutter removal algorithm is the simplest and effective method for single-time scanning of the concealed targets, in a realistic scenario.