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We study the surface perturbation of a viscous fluid adequately heated from below. We shown that under appropriate perturbations to the static solution the system exhibit oscillatory instabilities governed by the Kadomtsev-Petviashvili equation or by the (2+1) dimensional Burgers equation.
In this paper a wideband antenna integrated with a MMIC is reported for electronic warfare applications. The active device is located inside the mechanical structure to add new functionalities to the antenna unit and enhance strongly its performances. The new functionalities include a high power protection device, a balun, an impedance transformer and a wideband amplifier. The antenna gain is improved...
In this paper a novel Radar Absorbing Material (RAM) structure with enhanced reflecting and absorbing properties in the 2–18 GHz band is presented. Shielding properties are improved with nano-graphene particles deposited on the surface of composite materials. The nanomaterial allows an ad hoc optimization of the electrical properties of the bulk material in order to obtain a substantial improvement...
In this contribution, a novel dual polarized broadband passive antenna, aimed at Direction Finding (DF) applications in the UHF spectrum, is presented. Preliminary results, obtained by full wave simulations, confirm the stability of the antenna radiation pattern over the whole working frequency band, thus resulting an excellent candidate as electromagnetic sensor for dual polarized DF systems.
This paper describes a compact antenna system architecture for DOA estimation in electronic warfare environments. The single antenna modules are intended to cover a certain frequency range each. This super-heterodyne approach allows covering a bandwidth larger than four octaves. The novelty of the presented structure, with respect to typical ESM/ELINT approaches, lies in a spatially shared solution...
A novel horizontally polarized omnidirectional antenna is here presented, exhibiting broad-band behavior as well as low profile and weight. Printed circuit technology is chosen in the design process in order to reduce the overall final production cost, moreover, the use of external lumped-element matching networks has been avoided to keep the antenna as simple and environmentally robust as possible...
In this paper we present a modified quasiorthogonal space-time block coding (M QO-STBC) scheme with full diversity and code gain distance (CGD) for use in asynchronous relay networks. We implement an orthogonal frequency division multiplexing (OFDM) scheme with cyclic prefix (CP) at the source to mitigate the effects of random delays between the relay nodes and the destination caused by asynchronism...
In this paper we evaluate the outage probability in cooperative networks using the channel conditions in order to select the best four relays from a set of N relays and then the chosen relays are used for cooperation between the source and the destination. Expressions for outage probability are derived for a frequency flat Rayleigh-fading environment by using theoretic analysis of the probability...
The reduction of design and production time is an important factor in the actual Economic System. Near Field measurement techniques give fast and accurate way for complete characterization of antennas. This paper describes the spherical near field test bench by SATIMO called “StarLab” that works in 0.8 to 18 GHz frequency band . Measured patterns of some different antennas will be presented and compared...
A novel planar low profile UWB sinuous slot radiating element suitable for ESM and ECM systems applications is presented. The radiating element is designed to cover a frequency band wider than one octave (i.e. 3:1) and to be a very “low profile” antenna: its size along boresight axis is smaller than λ0/4, where λ0 is the wavelength at the central frequency of operation. The design of a novel sinuous...
In this paper we consider quasi-orthogonal distributed space-time block codes (D-STBCs) for application in cooperative wireless network. One scheme is designed by using appropriate signal rotations and set partitioning of two quasi-orthogonal codebooks. The codebooks are formed from the union of two modified quasi-orthogonal codes, then the union is pruned down by one-half. In contrast, the closed-loop...
In this paper we exploit a quasi-orthogonal space time type block code with maximal distance property within a four relay network. This modified code is built from set partitioning a larger codebook formed from two quasi-orthogonal space time block codes with different signal rotations. In simulation studies the new code is shown to outperform previous open loop and closed loop schemes in terms of...
A systematic approach for the design of an ultra wideband (4-18 GHz) radiating element in dual polarized planar phased-array application is presented. Two different radiating elements have been selected: the Vivaldi notch element, fed by strip-line, and the four arms Sinuous element, fed by ultra wide band double printed balun. Return loss, gain and patterns have been simulated and optimized considering...
In this article the design, fabrication and test of X-band and 2-18 GHz wideband high power SPDT MMIC switches in GaN technology are presented. Said switches have demonstrated state-of-the-art performance and RF fabrication yields better than 65%. In particular the X-band switch exhibits an on-state power handling capability of better than 37 dBm at the 1 dB insertion loss compression point and the...
Recent neuroimaging studies have shown consistent neural correlates of meditation states and traits. These studies present important implications for understanding core brain systems, also for clinical applications. In our fMRI study, we investigate neural correlates of both concentrative and mindfulness-based meditation forms, in long-term meditators (Buddhist monks). We found selective activation...
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