Open AccessFocused Planar Electromagnetic Waves for Enhanced Near-Field Microwave Imaging With Verification Using Tapered Gradient-Index Lens Antenna
Author(s) -
Azin S. Janani,
Amin Darvazehban,
Sasan Ahdi Rezaeieh,
Amin M. Abbosh
Publication year - 2022
Publication title -
ieee access
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 127
ISSN - 2169-3536
DOI - 10.1109/access.2022.3199002
Subject(s) - aerospace , bioengineering , communication, networking and broadcast technologies , components, circuits, devices and systems , computing and processing , engineered materials, dielectrics and plasmas , engineering profession , fields, waves and electromagnetics , general topics for engineers , geoscience , nuclear engineering , photonics and electrooptics , power, energy and industry applications , robotics and control systems , signal processing and analysis , transportation
Radar-based algorithms for electromagnetic (EM) imaging are developed based on the assumption that EM has a local planar wave front inside the imaging domain. However, this might not be the case for majority of utilized antennas as the imaged object is usually located within the near-field zone of the antenna. The impact of that assumption on imaging accuracy and whether utilizing an antenna that can create a focused planar wave front inside the imaging domain improves EM imaging are investigated in torso imaging as an example. Thus, three types of antennas are used to scan the torso; 1) bio-matched loop-dipole, 2) Gradient-Index lens (GRIN), and 3) Tapered GRIN (T-GRIN) lens antenna. The proposed T-GRIN lens antennas is designed to create a focused plane wave propagation inside the torso using tapered trapezoid water-filled cavities inside a host medium. The proposed design improves penetration depth by 33% compared to conventional GRIN lens and 75% compared to the bio-matched loop-dipole antenna, in a wide fractional bandwidth of 83% at 0.7-1.7 GHz. The realized results indicate that generating focused plane wave inside the imaged object, which is realized using T-GRIN lens antenna, improves the detection accuracy by 15 % and 56% compared to conventional GRIN lens and bio-matched loop-dipole antennas, respectively. Moreover, the localization accuracy is improved by 54.5% and 100% compared to conventional GRIN lens and bio-matched loop-dipole antenna, respectively. This study highlights the importance of creating focused planar wave front within the imaging domain for improved detection and localization using microwave techniques.