96 research outputs found
Single-Order Transmission Diffraction Gratings based on Dispersion Engineered All-dielectric Metasurfaces
A single-order transmission diffraction grating based on dispersion
engineered all-dielectric metasurfaces is proposed and its wavelength
discriminating properties have been theoretically described and confirmed using
numerical simulations. The metasurface is designed using a 2D array of
all-dielectric resonators, which emulates a Huygens source configuration to
achieve a perfect match to free-space in broad bandwidth. Using a holey
dielectric nanodisk structure as the unit cell, the resonant wavelength is
tapered across the metasurface to engineer the wavelength dependent spatial
phase gradient, to emulate a dispersive prism. Consequently, different
wavelengths are steered towards different directions and thus are discriminated
on the output image plane. Due to subwavelength periodicities involved, the
wavelength discrimination is achieved directly in the zeroth diffraction order
of the device, unlike conventional diffraction gratings, thereby providing a
high efficiency wavelength discriminating device.Comment: 5 pages, 5 figure
Real-Time Dispersion Code Multiple Access (DCMA) for High-Speed Wireless Communications
We model, demonstrate and characterize Dispersion Code Multiple Access (DCMA)
and hence show the applicability of this purely analog and real-time multiple
access scheme to high-speed wireless communications. We first mathematically
describe DCMA and show the appropriateness of Chebyshev dispersion coding in
this technology. We next provide an experimental proof-of-concept in a 2 X 2
DCMA system. Finally,we statistically characterize DCMA in terms of bandwidth,
dispersive group delay swing, system dimension and signal-to-noise ratio
Magneto-Electric Dipole Antenna Arrays
A planar magneto-electric (ME) dipole antenna array is proposed and
demonstrated by both full-wave analysis and experiments. The proposed structure
leverages the infinite wavelength propagation characteristic of composite
right/left-handed (CRLH) transmission lines to form high-gain magnetic
radiators combined with radial conventional electric radiators, where the
overall structure is excited by a single differential feed. The traveling-wave
type nature of the proposed ME-dipole antenna enables the formation of
directive arrays with high-gain characteristics and scanning capability. Peak
gains of 10.84 dB and 5.73 dB are demonstrated for the electric dipole and
magnetic-dipole radiation components, respectively.Comment: 9 pages, 17 figure
Unveiling Magnetic Dipole Radiation in Phase-Reversal Leaky-Wave Antennas
The radiation principle of travelling-wave type phase-reversal antennas is
explained in details, unveiling the presence of magnetic-dipole radiation in
addition to well-known electric dipole radiation. It is point out that such
magnetic dipole radiation is specific to the case of traveling-wave
phase-reversal antennas whereas only electric-dipole radiation exists in
resonant-type phase-reversal antennas. It is shown that a phase-reversal
travelling-wave antenna alternately operates as an array of magnetic dipoles
and an array of electric-dipoles during a time-harmonic period. This radiation
mechanism is confirmed through both full-wave and experimental results.Comment: 4 pages, 3 figure
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