Lipworth Guy, Rose Alec, Yurduseven Okan, Gowda Vinay R, Imani Mohammadreza F, Odabasi Hayrettin, Trofatter Parker, Gollub Jonah, Smith David R
Appl Opt. 2015 Nov 1;54(31):9343-53. doi: 10.1364/AO.54.009343.
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.
最近，一种基于超材料的频率分集孔径已被引入到微波和毫米波成像领域。该孔径的一般形式是平行板波导，其中在上极板上图案化的互补超材料元件将能量从波导模式耦合到场景中。为了在制造和实验之前可靠地预测这种孔径的成像性能，有必要拥有一个能够预测孔径辐射的精确正向模型、一个用于场景中任意目标散射的模型以及一组允许从任意测量集进行场景估计的图像重建方法。在此，我们引入一个正向模型，其中超材料元件被近似为可极化磁偶极子，由波导内传播的场激发。模型中使用的偶极子可以具有任意指定的极化特性。或者，可以将从实际超材料样品测量得到的场分解为一组有效的偶极辐射器，从而对实际样品的性能进行定量建模并与模拟孔径进行比较。为了验证我们模型的有效性，我们使用一个工作在K波段频谱（18 - 26.5 GHz）的虚拟多孔径成像系统模拟测量和场景重建，并将其性能与一个实验系统进行比较。
