Physical Optics Modeling of AMC Checkerboard Surfaces for RCS-Reduction and Low Backscattering Retrodirective Array

• Other Authors: ALYAHYA, MESHAAL (Author)
• Format: Doctoral Thesis
• Language: English
• Published: 2020
• Subjects: Electromagnetics
• Online Access: http://hdl.handle.net/2286/R.I.62950

abstract: Artificial magnetic conductor (AMC) surfaces have the unique electromagnetic property that the phase of the reflected fields imitate those of perfect magnetic conductors (PMCs). When a perfect electric conductor (PEC) and an AMC surface are placed on the same plane and illuminated by a plane wave, destructive interference occurs between the fields (due to 180 degrees phase difference between the reflected fields of each surface). In this dissertation, a design procedure is introduced where a refined algorithm is developed and employed on single-band AMCs leading to a 10-dB RCS-reduction bandwidth of 80%. The AMC circuit model is judiciously utilized to reduce the substrate thickness while simultaneously increasing the bandwidth of the AMC surfaces. Furthermore, dual-band AMC surfaces are synthesized and utilized in combination with single-band AMC surfaces to extend the 10-dB RCS-reduction bandwidth from 80% to about 99%. Employing the proposed design procedure, a 99% bandwidth of 10-dB RCS-reduction bandwidth is achieved while reducing the thickness of the substrate by 20%. The second topic of this dissertation aims at analytically modeling the scattering of planar checkerboard surfaces. The high-frequency asymptotic method, Physical Optics (PO), is utilized to analyze the scattering characteristics of complex structures since the PO is computationally efficient and provides intuitive physical insight. Closed-form formulations developed using PO are used to predict the scattering patterns of checkerboard planar surfaces. The PO-based data compare well, along and near specular directions, with simulations by the full-wave Finite Element Method (FEM). Finally, a Van Atta retrodirective reflector with low backscattering is designed and developed using a microstrip antenna array. Conventional retrodirective reflectors are sensitive to interference by the fields scattered by the antenna structure. By using a virtual feeding network, structural mode scattering is identified and canceled using AMC technology. === Dissertation/Thesis === Doctoral Dissertation Electrical Engineering 2020