180 research outputs found
W. M. Barnes Company, A Corporation v. Sohio Natural Resources Company, A Corporation, Formerly Sohio Petroleum Company, A Corporation : Appellant\u27s Brief
Appeal from the Judgment of the Fourth District Court for Uintah County Honorable George E. Ballif, Judg
A Self-Replicating Single-Shape Tiling Technique for the Design of Highly Modular Planar Phased Arrays -- The Case of L-Shaped Rep-Tiles
The design of irregular planar phased arrays (PAs) characterized by a
highly-modular architecture is addressed. By exploiting the property of
self-replicating tile shapes, also known as rep-tiles, the arising array
layouts consist of tiles having different sizes, but equal shape, all being
generated by assembling a finite number of smaller and congruent copies of a
single elementary building-block. Towards this end, a deterministic
optimization strategy is used so that the arising rep-tile arrangement of the
planar PA is an optimal trade-off between complexity, costs, and fitting of
user-defined requirements on the radiated power pattern, while guaranteeing the
complete overlay of the array aperture. As a representative instance, such a
synthesis method is applied to tile rectangular apertures with L-shaped tromino
tiles. A set of representative results, concerned with ideal and real antenna
models, as well, is reported for validation purposes, but also to point out the
possibility/effectiveness of the proposed approach, unlike state-of-the-art
tiling techniques, to reliably handle large-size array apertures.Comment: 56 pages, 22 figure
Reflectarray antennas for dual polarization and broadband telecom satellite applications
A reflectarray antenna with improved performance is proposed to operate in dual-polarization and transmit-receive frequencies in Ku-band for broadcast satellite applications. The reflectarray element contains two orthogonal sets of four coplanar parallel dipoles printed on two surfaces, each set combining lateral and broadside coupling. A 40-cm prototype has been designed, manufactured, and tested. The lengths of the coupled dipoles in the reflectarray cells have been optimized to produce a collimated beam in dual polarization in the transmit and receive bands. The measured radiation patterns confirm the high performance of the antenna in terms of bandwidth (27%), low losses, and low levels of cross polarization. Some preliminary simulations at 11.95 GHz for a 1.2-m antenna with South American coverage are presented to show the potential of the proposed antenna for spaceborne antennas in Ku-band
Amorphous-silicon visible-light detector integrated on silicon nitride waveguides
: Visible-light integrated photonics is emerging as a promising technology for the realization of optical devices for applications in sensing, quantum information and communications, imaging, and displays. Among the existing photonic platforms, high-index-contrast silicon nitride (Si3N4) waveguides offer broadband transparency in the visible spectral range and a high scale of integration. As the complexity of photonic integrated circuits (PICs) increases, on-chip detectors are required to monitor their working point for reconfiguration and stabilization operations. In this Letter, we present a semi-transparent in-line power monitor integrated on Si3N4 waveguides that operates in the red-light wavelength range (660 nm). The proposed device exploits the photoconductivity of a hydrogenated amorphous-silicon (a-Si:H) film that is evanescently coupled to an optical waveguide. Experimental results show a responsivity of 30 mA/W, a sensitivity of -45 dBm, and a sub-µs time response. These features enable the use of the proposed photoconductor for high-sensitivity monitoring and control of visible-light Si3N4 PICs
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