The surface integral equation (SIE) method is one of the most popular numerical methods for the electromagnetic analysis of any kind of homogeneous and piecewise homogeneous dielectric, metallic, or composite objects. This work focuses on the tangential formulations (usually more accurate than the normal ones), paying special attention to their capability of modeling the plasmonic behavior of metals at optical and quasi-optical frequencies, in which the localized surface plasmon resonances (LSPRs) bring out significant accuracy problems. The authors present a new tangential SIE, the improved combined tangential formulation (ICTF), in which the fast convergence behavior of the original CTF is combined with a high accuracy, because of the first-kind nature of the new ICTF. Some numerical results are shown to illustrate the behavior and accuracy of the proposed formulation, even when dealing with highly resonant plasmonic problems.

This article presents a physical optics-based simulator for the analysis of terahertz (THz) imaging systems. The simulation starts by calculating the electromagnetic interactions inside the multireflector system and the incident field that the focusing system creates on the target under inspection. In a second step, the electric field that the modeled target scatters back to the system receiver, is also calculated. This allows to predict the imaging behavior of the system for different targets before manufacturing. The simulator results are validated by using measurements from an existing 300-GHz standoffimaging system. This contribution aims to help in the development of better imaging systems for security applications in the near future.

The aim of this work is to design a shaped solid reflector mechanically reconfigurable and capable to comply changeable coverage requirements using few actuators. The method directly optimizes the actuators with a heuristic technique based in ant colony algorithm, where both mechanical and electromagnetic models are integrated in the same cost function in a simple and effective way using the mechanical concept of stiffness matrix. To illustrate this technique, we present an example of a reconfigurable reflector antenna that covers South America with a minimum directivity and, for some reduction of this minimum directivity, is able to increase the directivity in selected regions to respond to rain and other changing conditions in a few seconds.

This study introduces an innovative optimization method to identify the optimal configuration of a sparse symmetric 2D array for applications in security, particularly multistatic imaging. Utilizing genetic algorithms (GAs) in a sophisticated optimization process, the research focuses on achieving the most favorable antenna distribution while mitigating the common issue of secondary lobes in sparse arrays. The main objective is to determine the ideal configuration from specific design parameters, including hardware specifications such as number of radiating elements, minimum spacing, operating frequency range, and image separation distance. The study employed a cost function based on the the point spread function (PSF), the system response to a point source, with the goal of minimizing the secondary lobe levels and maximizing their separation from the main lobe. Advanced simulation algorithms based on physical optics (PO) were used to validate the presented methodology and results.