A telemetry antenna system for unmanned air vehicles

This paper presents a low VSWR high gain telemetry antenna system manufactured for UAVs that provides 360± coverage in the roll plane of the UAV. Proposed telemetry antenna system includes four telemetry antennas, one power divider that has one input and four output terminals which feeds the telemetry antennas with equal magnitude and phase. Proposed high gain telemetry antennas are based on the feeding of the microstrip patch antenna via aperture coupling. Full coverage in the roll plane of the UAV is obtained by using circular array configuration of telemetry antennas. RF power divider is designed by using couple of Wilkinson power dividers with equal line lengths and impedance sections from input terminal to the all four output terminals

Quantum Fisher Information of W States in Decoherence Channels

We study the quantum Fisher information (QFI) of W states analytically with respect to SU(2) rotations in the basic decoherence channels i.e. depolarizing (DPC), amplitude damping (ADC) and phase damping (PDC), and present the interesting behavior of QFI of W states, especially when compared to that of GHZ states [Ma et al., Phys. Rev. A, 84, 022302 (2011)]. We find that when initially pure W states are under decoherence, i) DPC: as decoherence starts and increases, QFI smoothly decays; ii) ADC: just as decoherence starts, QFI exhibits a sudden drop to the shot noise level and as decoherence increases, QFI continues to decrease to zero and then increases back to the shot noise level; iii) PDC: just as decoherence starts, a sudden death of QFI occurs and QFI remains zero for any rate of decoherence, therefore W states in phase damping channel do not provide phase sensitivity. We also find that, on the contrary to GHZ states, pure or decohered W states are not sensitive with respect to rotations in z direction and the sensitivities with respect to rotations in x and y directions are equal to each other, implying no sudden change points of QFI due to competition between directions.Comment: 3 pages, 1 (eps) figure. Comments are welcom

Magnetization reversal behavior in complex shaped Co nanowires: a nanomagnet morphology optimization

A systematic micromagnetic study of the morphological characteristic effects over the magnetic static properties of Co-based complex shaped nanowires is presented. The relevance of each characteristic size (i.e. length L, diameter d, and size of the nanowires head T) and their critical values are discussed in the coercive field optimization goal. Our results strongly confirms that once the aspect ratio (L/d) of the nanowire is bigger than around 10, the length is no more the pertinent parameter and instead the internal diameter and the shape of the nanowires play a key role. We attribute this behavior to the non uniform distribution of the demagnetizing field which is localized in the nanowires head and acts as a nucleation point for the incoherent magnetization reversal. Finally, angular dependence of the magnetization are simulated and compared to the case of a prolate spheroid for all considered morphologies.Comment: 7 pages, 6 figure