Comprehensive simulation platform for a metamaterial imaging system

Abstract

Recently, a frequency-diverse, metamaterial-based aperture has been introduced in the context of microwave and millimeter wave imaging. The generic form of the aperture is that of a parallel plate waveguide, in which complementary metamaterial elements patterned into the upper plate couple energy from the waveguide mode to the scene. To reliably predict the imaging performance of such an aperture prior to fabrication and experiments, it is necessary to have an accurate forward model that predicts radiation from the aperture, a model for scattering from an arbitrary target in the scene, and a set of image reconstruction approaches that allow scene estimation from an arbitrary set of measurements. Here, we introduce a forward model in which the metamaterial elements are approximated as polarizable magnetic dipoles, excited by the fields propagating within the waveguide. The dipoles used in the model can have arbitrarily assigned polarizability characteristics. Alternatively, fields measured from actual metamaterial samples can be decomposed into a set of effective dipole radiators, allowing the performance of actual samples to be quantitatively modeled and compared with simulated apertures. To confirm the validity of our model, we simulate measurements and scene reconstructions with a virtual multiaperture imaging system operating in the K-band spectrum (18-26.5 GHz) and compare its performance with an experimental system.

Learned Integrated Sensing Pipeline: Reconfigurable Metasurface Transceivers as Trainable Physical Layer in an Artificial Neural Network

“…As detailed in Section I in the Supporting Information, our forward model consists of three steps: i) extracting each metamaterial element's dipole moment while taking tuning state and interelement coupling into account; [31] ii) propagating the radiated field to the scene; [32] iii) evaluating the scattered field. This dipole approximation is facilitated by the intrinsic sub-wavelength nature of the metamaterial elements.…”

Analysis of a Waveguide-Fed Metasurface Antenna

“…II we introduce the underlying structure of the metasurface antenna and the analysis framework, in which each metamaterial element is conceptually replaced by a polarizable dipole. This modeling approach has been used for waveguide-fed metasurface antennas presented in prior work, and has successfully been implemented in numerical tools for characterizing metasurface apertures [34,35]. From this simple model we obtain the radiated far-field pattern.…”

Polarizability extraction of complementary metamaterial elements in waveguides for aperture modeling

“…Used as coatings, metasurfaces can control the absorbance and emissivity of a surface, and thus have relevance to thermophotovoltaics [34], detectors and sources [35][36][37][38][39][40][41]. Given the capabilities of metasurfaces to control waves, but without many of the limitations of volumetric metamaterials, metasurfaces have proven a good match for commercialization efforts, with many serious applications now being pursued, including satellite communications [42][43][44], radar [45], and microwave imaging [46][47][48].…”