International Professional University of Technology in Nagoya Repository
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A switched-beam conformal array with a 3-D beam forming capability in C-band
No full textInternational audienceA 12-element conical antenna array made of four linear subarrays regularly spaced by 90° is proposed in C-band for communication applications on high velocity flying platforms. The beam forming network is stacked below the radiating part, and allows steering the subarray beam of the conical array. The performance of the main building blocks is described in detail, both numerically and experimentally. The measured radiation characteristics of the phased array are in good agreement with the simulation results between 5 and 5.4 GHz for all configurations with beam pointing directions varying between 30° and 110° in the elevation plane. © 2017 IEEE
Design and characterization of a compact Artificial Magnetic Conductor in the UHF band
No full textInternational audienceArtificial Magnetic Conductors (AMCs) design and characterization in the UHF band is a big challenge while realizing low-profile antenna. In fact, AMCs unit cell often balance large geometries with high dielectric constants to achieve the desired frequency target while maintaining a minimal thickness. A compact AMC unit cell achieving a 37% reduction in the largest dimension (or 60% of surface reduction) is proposed in this paper. Numerical technique is applied to simulate the behavior of the considered AMC and the conventional one based on mushroom-like unit cell. Two measurements methods in anechoic chamber (monostatic RCS and TEM cell measurements) have been compared to characterize the manufactured prototypes. Good agreement has been found between simulations and measurements. © 2017 IEEE
Long slot array for wireless power transmission
No full textInternational audienceRetrodirective antennas used for radiative wireless power transfer (WPT) are typically resonant and exhibit strong backscatter, a limited field of view and small bandwidth. These limitations are here overcome by using an array of long slots fed by parallel plate waveguides (PPWs). It is shown that the array can collect the total power impinging from a remote source over a large field of view and bandwidth. The conclusions arrived at for the infinite case are extended to the finite case through full-wave simulations. © 2017 Euraap
Design of planar implantable compact antennas for vaginal sensor for early detection of calving
No full textInternational audienceTwo implantable antennas radiating at the Industrial, Scientific, and Medical (ISM) frequencies 868 and 915 MHz were proposed to be employed in a vaginal sensor. These structures were developed in the context of the industrial project "Vel'Phone sensor" funded by Medria, a French company for monitoring services. The compact antennas consist on a meander monopole and a metamaterial (MTM)-inspired monopole. Both antennas were optimized in free space and in a model of the environment faithful to reality (inside the cow vagina). Prototypes were manufactured and tested using liquid phantom. We proved the potential of the overall system integrated with an electronic card and biocompatible material in real conditions. Simulated and measured results are presented and discussed. © 2017 Euraap
Broadband CTS antenna array at E-band
No full textInternational audienceA compact 32-slot continuous transverse stub (CTS) antenna array operating at E-band is proposed here. It is excited by a hollow parallel plate waveguide (PPW) corporate feed network to insure a broad band operation. A parabolic pillbox coupler is used to create the requested current line exciting for the PPW beamformer. The pillbox coupler is fed by a substrate integrated waveguide (SIW) horn located in the focal plane of the parabola. The most important features of the antenna building blocks are described in detail, and the numerical results demonstrate the excellent performance of the proposed antenna. A reflection coefficient lower than -19 dB and a gain larger than 31 dBi are obtained over a 19% fractional bandwidth spanning between 71 and 86 GHz. The proposed antenna architecture is an innovative solution for E-band backhauling applications for next generation 5G networks. © 2017 Euraap
Enhancing breast cancer imaging at millimeter waves using focusing techniques
No full textInternational audienceMedical imaging using electromagnetic waves is a promising field of study, due to its non invasive nature and relatively low cost. Typically, it is pursued at frequencies in the microwave regime to provide adequate penetration depth. However, an increase of the frequency of operation is beneficial in order to improve the resolution, but it is accompanied by increased tissue losses. In this work we investigate the possibility to increase the penetration depth of systems for breast imaging at the lower bound of millimeter waves (30 GHz). The proposed technique consists in a near-field focusing of the radiated field with an enhanced penetration depth. © 2017 IEEE
Loss Analysis of a Reflectarray Cell Using ANNs with Accurate Magnitude Prediction
No full textInternational audienceThis paper proposes a design methodology to improve the Artificial Neural Networks (ANNs) modeling of reflectarray (RA) cells with regards to the prediction of reflection coefficients magnitude. It is applied to model both types of RA cells (capacitive and inductive) with 5 inputs parameters. The results demonstrate that the final ANNs models are reliable and accurate with an average error on the reflection coefficient magnitude of the scattering matrix (|R11|) of -66dB and -69dB respectively for the capacitive and inductive cells. This accurate prediction of magnitude allows rejecting a priori any cell with loss exceeding a prescribed threshold. Comparison of two canonical RA layouts shows the benefit that could be expected in a synthesis process
Wideband and Large Coverage Continuous Beam Steering Antenna in the 60-GHz Band
No full textInternational audienceA wideband and continuous beam steering flat antenna is proposed in the 60-GHz band. The antenna consists of two layers and is made of two parts: 1) a feeding network and 2) a slotted plate. The relative rotation movement between the two antenna parts generates a phase gradient across the radiating part, and a continuous beam is generated in the upper hemisphere. The mechanical movement between the two antenna parts is facilitated by the use of gap waveguides; therefore, no electrical contact is needed between the two metallic parts. To validate the antenna concept, an antenna has been designed and fabricated in the 60-GHz band. Good agreement has been obtained between the simulations and the measurements. The antenna field of view is up to +/- 60 degrees. The antenna bandwidth is up to 13% for VSWR <2. The loss within the antenna structure is estimated to be around 0.86 dB
On fault-tolerant path optimization under QoS constraint in multi-channel wireless networks
No full textInternational audienceIn multi-channel wireless networks, a fundamental problem is to find node-disjoint paths minimising global cost or the maximum individual path cost, under the constraint that each path operates on a separate channel to maximise the fault tolerance and robustness against channel instability and malicious attacks. Meanwhile, the quality of service (QoS) requirement (e.g., in terms of end-to-end delay) needs to be satisfied on each path. In this paper, we provide a comprehensive formulation and analysis on this multi-path optimization problem by casting it to the problem k-disjoint path with different colours (k-DPDC). We further formulate the Restricted MinSum k-DPDC and Restricted MinMax k-DPDC to denote the problems of finding multiple node- and channel-disjoint paths minimising the global cost and the maximum individual path cost under the QoS constraint on the path end-to-end delay. Given the NP-hardness of both problems, we focus on directed acyclic graphs and propose fully polynomial-time approximation algorithms for both problems
Multivariate Linear Time-Frequency modeling and adaptive robust target detection in highly textured monovariate SAR image
No full textInternational audienceUsually, in radar imaging, the scatterers are supposed to respond the same way regardless of the angle from which they are viewed and have the same properties within the emitted spectral bandwidth. Nevertheless, new capacities in SAR imaging (large bandwidth, large angular extent) make this assumption obsolete. An original application of the Linear Time-Frequency Distributions (LTFD) in SAR imaging allows to highlight the spectral and angular diver-sities of these reflectors. This methodology allows to transform a monovariate SAR image onto multivariate SAR image. Robust detection schemes in Gaussian or non Gaussian background (Adap-tive Matched Filter (AMF), Adaptive Normalized Matched Filter (ANMF), Anomaly Kelly Detector) associated with classical or robust Covariance Matrix Estimates (Sample Covariance Matrix (SCM), M-estimators) can then be applied exploiting these diver-sities. The combined two-methodologies show their very good performance for target detection