SAR Image Simulation of Complex Target Including Multiple Scattering

We present a GPU-based computation for simulating the synthetic aperture radar (SAR) image of the complex target. To be more realistic, we included the multiple scattering field and antenna pattern tracking in producing the SAR echo signal for both Stripmap and Spotlight modes. Of the signal chains, the computation of the backscattering field is the most computationally intensive. To resolve the issue, we implement a computation parallelization for SAR echo signal generation. By profiling, the overall processing was identified to find which is the heavy loading stage. To further accommodate the hardware structure, we made extensive modifications in the CUDA kernel function. As a result, the computation efficiency is much improved, with over 224 times the speed up. The computation complexity by comparing the CPU and GPU computations was provided. We validated the proposed simulation algorithm using canonical targets, including a perfectly electric conductor (PEC), dielectric spheres, and rotated/unrotated dihedral corner reflectors. Additionally, the targets can be a multi-layered dielectric coating or a layered medium. The latter case aimed to evaluate the polarimetric response quantitively. Then, we simulated a complex target with various poses relative to the SAR imaging geometry. We show that the simulated images have high fidelity in geometric and radiometric specifications. The decomposition of images from individual scattering bounce offers valuable exploitation of the scattering mechanisms responsible for imaging certain target features.

A Wide-Angle Scanning Sub-Terahertz Leaky-Wave Antenna Based on a Multilayer Dielectric Image Waveguide

This paper presents a new layered dielectric leaky-wave antenna (LWA) for the sub-terahertz (THz) frequency range capable of efficient operation at the broadside with a wide beam scanning angle and stable gain. It consists of a conductor-backed alumina dielectric image line (DIL) with two different dielectric layers mounted on top of each other for performance improvement. The upper layer is a high permittivity RO6010 substrate to enhance the directivity as a superstrate and the lower layer is a low-permittivity RT/duroid 5880 substrate stacked on the alumina DIL to prevent the probable excitation of higher-order modes in the DIL channel. A 15-element linear array of radiating overlapped discs is used to mitigate the open stop-band (OSB) problem, fed by the mentioned waveguide, was designed and simulated at frequencies around 170 GHz. The dominant mode of the layered dielectric waveguide is perturbed by the infinite space harmonics generated by two sets of overlapped discs periodically sandwiched between the layers. It exhibited a relatively wide impedance bandwidth of 28.19% (157.5–206 GHz). Its radiation mechanism has been widely studied through simulations. The results revealed that the antenna provides a wide scanning capability through the broadside from −23° to 38°, covering the frequency range between 157.5 GHz and 201.5 GHz. For an array with 15 radiating elements, the simulated peak gain in the band is 15 dBi and the broadside gain is 13.6 dBi at 172 GHz.