Discrete Dipole Approximation Applied to Highly Directive Slotted Waveguide Antennas

Pulido-Mancera, Laura; Zvolensky, Tomas; Imani, Mohammadreza F.; Bowen, Patrick T.; Valayil, Minu; Smith, David R.

doi:10.1109/lawp.2016.2538202

Cited by 43 publications

(17 citation statements)

References 22 publications

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“…The metasurfaces considered throughout this paper also share this feature, since they also leak energy from the guided wave through the metamaterial elements. In other words, the methodology developed in this paper can also be applied to leaky wave antennas for modeling, simulation, and designing [89].…”

Section: Simulated Results For the Rectangular Waveguidementioning

confidence: 99%

Polarizability extraction of complementary metamaterial elements in waveguides for aperture modeling

et al. 2017

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We consider the design and modeling of metasurfaces that couple energy from guided waves to propagating wavefronts. This is a first step towards a comprehensive, multiscale modeling platform for metasurface antennas-large arrays of metamaterial elements embedded in a waveguide structure that radiates intro free-space-in which the detailed electromagnetic responses of metamaterial elements are replaced by polarizable dipoles. We present two methods to extract the effective polarizability of a metamaterial element embedded in a one-or two-dimensional waveguide. The first method invokes surface equivalence principles, averaging over the effective surface currents and charges within an element to obtain the effective dipole moments; the second method is based on computing the coefficients of the scattered waves within the waveguide, from which the effective polarizability can be inferred. We demonstrate these methods on several variants of waveguidefed metasurface elements, finding excellent agreement between the two, as well as with analytical expressions derived for irises with simpler geometries. Extending the polarizability extraction technique to higher order multipoles, we confirm the validity of the dipole approximation for common metamaterial elements. With the effective polarizabilities of the metamaterial elements accurately determined, the radiated fields generated by a metasurface antenna (inside and outside the antenna) can be found self-consistently by including the interactions between polarizable dipoles. The dipole description provides an alternative language and computational framework for engineering metasurface antennas, holograms, lenses, beam-forming arrays, and other electrically large, waveguide-fed metasurface structures.

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Section: Simulated Results For the Rectangular Waveguidementioning

confidence: 99%

Polarizability extraction of complementary metamaterial elements in waveguides for aperture modeling

et al. 2017

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“…This assumption is usually valid when metamaterial elements are weakly coupled to the guided mode [20]. For cases with strong coupling metamaterial element, one can include such coupling using coupled dipole models [39]. This model and its implications (if any) on the massive MIMO system is beyond the scope of this paper and are left for future works.…”

Section: A Dynamic Metasurface Antennasmentioning

confidence: 99%

Dynamic Metasurface Antennas for Uplink Massive MIMO Systems

Shlezinger

Dicker²,

Eldar

et al. 2019

IEEE Trans. Commun.

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Massive multiple-input multiple-output (MIMO) communications are the focus of considerable interest in recent years. While the theoretical gains of massive MIMO have been established, implementing MIMO systems with large-scale antenna arrays in practice is challenging. Among the practical challenges associated with massive MIMO systems are increased cost, power consumption, and physical size. In this work we study the implementation of massive MIMO antenna arrays using dynamic metasurface antennas (DMAs), an emerging technology which inherently handles the aforementioned challenges. Specifically, DMAs realize large-scale planar antenna arrays, and can adaptively incorporate signal processing methods such as compression and analog combining in the physical antenna structure, thus reducing the cost and power consumption. We first propose a mathematical model for massive MIMO systems with DMAs and discuss their constraints compared to ideal antenna arrays. Then, we characterize the fundamental limits of uplink communications with the resulting systems, and propose two algorithms for designing practical DMAs for approaching these limits. Our numerical results indicate that the proposed approaches result in practical massive MIMO systems whose performance is comparable to that achievable with ideal antenna arrays.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…This agreement implies that the dipole model for the metamaterial elements is valid, and that interactions among the elements are not significant for the structures simulated. For cases where these element-to-element interactions are not negligible, a selfconsistent interacting dipole model can be applied for improved accuracy [35].…”

Section: Introductionmentioning

confidence: 99%

Analysis of a Waveguide-Fed Metasurface Antenna

et al. 2017

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The metasurface concept has emerged as an advantageous reconfigurable antenna architecture for beam forming and wavefront shaping, with applications that include satellite and terrestrial communications, radar, imaging, and wireless power transfer. The metasurface antenna consists of an array of metamaterial elements distributed over an electrically large structure, each subwavelength in dimension and with subwavelength separation between elements. In the antenna configuration we consider here, the metasurface is excited by the fields from an attached waveguide. Each metamaterial element can be modeled as a polarizable dipole that couples the waveguide mode to radiation modes. Distinct from the phased array and electronically scanned antenna (ESA) architectures, a dynamic metasurface antenna does not require active phase shifters and amplifiers, but rather achieves reconfigurability by shifting the resonance frequency of each individual metamaterial element. Here we derive the basic properties of a one-dimensional waveguide-fed metasurface antenna in the approximation that the metamaterial elements do not perturb the waveguide mode and are non-interacting. We derive analytical approximations for the array factors of the 1D antenna, including the effective polarizabilities needed for amplitude-only, phase-only, and binary constraints. Using full-wave numerical simulations, we confirm the analysis, modeling waveguides with slots or complementary metamaterial elements patterned into one of the surfaces.

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Discrete Dipole Approximation Applied to Highly Directive Slotted Waveguide Antennas

Cited by 43 publications

References 22 publications

Polarizability extraction of complementary metamaterial elements in waveguides for aperture modeling

Polarizability extraction of complementary metamaterial elements in waveguides for aperture modeling

Dynamic Metasurface Antennas for Uplink Massive MIMO Systems

Analysis of a Waveguide-Fed Metasurface Antenna

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