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Swirling jets and vortices can both be unstable to the centrifugal instability but with a different wavenumber selection: the most unstable perturbations for swirling jets in inviscid fluids have an infinite azimuthal wavenumber, whereas, for vortices, the ...
This communication presents a reconfigurable antenna capable of independently reconfiguring the operating frequency, radiation pattern and polarization. A switched grid of small metallic patches, known as pixel surface, is used as a parasitic layer to prov ...
Spatial filtering is the fundamental characteristic of microphone array based signal acquisition, which plays an important role in applications such as speech enhancement and distant speech recognition. In the array processing literature, this property is ...
An iterative procedure for the synthesis of uniform amplitude focused beam arrays is presented. Specifically, the goal is to optimize the locations of a fixed number of array elements with known excitations in order to synthesize narrow-beam low-sidelobe p ...
We report on the advanced optical characterizations of microfabricated solid immersion lenses with 2-mu m diameter, operating at lambda = 642 nm. The main feature, the spot size reduction, has been investigated by applying a focused Gaussian beam of NA = 0 ...
Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2012
A sound field on a line or in a plane has an effectively limited spatial bandwidth determined by the temporal frequency. Similar can be said for sound fields from far-field sources when analyzed on circular and spherical apertures. Namely, for a given freq ...
Future photonic circuits with the capability of high-speed data processing at optical frequencies will rely on the implementation of efficient emitters and detectors on the nanoscale. Towards this goal, bridging the size mismatch between optical radiation ...
Spatial filtering is the fundamental characteristic of microphone array based signal acquisition which plays an important role in applications such as speech enhancement and distant speech recognition. In the array processing literature, this property is f ...
The joint synthesis of the spatial power pattern and polarization of arbitrary arrays is addressed. Specifically, the proposed approach gives the solution to a frequently encountered problem, namely the array design (i.e., the determination of the radiatin ...
Institute of Electrical and Electronics Engineers2011
A slot array placed on the face of a cavity realized in substrate-integrated waveguide technology is presented. Guidelines to design similar antennas are provided. The design has been done with the help of commercial software. The result is a low-cost, dir ...