Passive Lossless Huygens Metasurfaces for Conversion of Arbitrary Source Field to Directive Radiation

By A. Epstein, George V. Eleftheriades. IEEE Transactions on Antennas and Propagation, 2014

152 citations recorded by the source corpus.

We present a semianalytical formulation of the interaction between a given source field and a scalar Huygens metasurface (HMS), a recently introduced promising concept for wavefront manipulation based on a sheet of orthogonal electric and magnetic dipoles. Utilizing the equivalent surface impedance representation of these metasurfaces, we establish that an arbitrary source field can be converted into directive radiation via a passive lossless HMS if two physical conditions are met: local power conservation; and local impedance equalization. Expressing the fields via their plane-wave spectrum and harnessing the slowly-varying envelope approximation, we obtain semianalytical formulae for the scattered fields, and prescribe the surface reactance required for the metasurface implementation. The resulting design procedure indicates that the local impedance equalization induces a Fresnel-like reflection, while local power conservation forms a radiating virtual aperture which follows the total excitation field magnitude. The semianalytical predictions are verified by finite-element simulations of HMSs designed for different source configurations. Besides serving as a flexible design procedure for HMS radiators, the proposed formulation also provides a robust mechanism to incorporate a variety of source configurations into general HMS models, as well as physical insight on the conditions enabling purely reactive implementation of this novel type of metasurfaces.

Subfields: Aerospace Engineering, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/aa97a96765fd1563731ec57eb509dd2c0936be4f

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Citations in the corpus

Perfect control of reflection and refraction using spatially dispersive metasurfaces (2016, background): “However, even this approach cannot ensure ideal performance [7,17], because these symmetric layers cannot be matched to impedances of two propagating waves (incident and transmitted) in different directions, and, therefore, they inevitably produce some reflections.”
Wave-front Transformation with Gradient Metasurfaces (2016, background): “We show in the following that this picture is inherently approximate, as it does not consider the relevance of impedance matching in the scattering process [29].”
Broadband Double-Layered Huygens’ Metasurface Lens Antenna for 5G Millimeter-Wave Systems (2020, background): “For example, short conductor traces are typically used for electric dipoles, and metallic ring resonators are typically used for equivalent magnetic dipoles [40], [41].”
Arbitrary Power-Conserving Field Transformations With Passive Lossless Omega-Type Bianisotropic Metasurfaces (2016, background): “Although for moderate angles HMSs can implement plane-wave refraction with small reflections [8], they are not capable of completely eliminating them [10], [21], and they become more significant as the difference between the incident and transmitted wave impedances becomes larger [27].”
Reflectionless Wide-Angle Refracting Metasurfaces (2016, background): “In [4] and [11], slight reflections are permitted to avoid active or lossy Huygens’ sources, permitting a rigorous analytical formulation.”
A Metasurfaces Review: Definitions and Applications (2019, background): “In [96], Huygen’s metasurfaces have been proposed to convert a non-directive beam from an arbitrary source to a directive one.”