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Bernard L.,French German Research Institute of Saint Louis | Chertier G.,French German Research Institute of Saint Louis | Sauleau R.,CNRS Institute of Electronics and Telecommunications, Rennes
IEEE Antennas and Wireless Propagation Letters | Year: 2011

A reduced-size wideband single-feed circularly polarized patch antenna is introduced for telemetry applications in S-band around 2300 MHz. The proposed structure consists of a slot-loaded patch antenna printed over an optimized metamaterial-inspired reactive impedance substrate (RIS). We demonstrate, step by step, the main role of each antenna element by comparing numerically and experimentally the performance of various antenna configurations: antenna over a single- or dual-layer substrate, standard patch or slot-loaded patch, antenna with or without RIS. The final optimized structure exhibits an axial-ratio bandwidth of about 15% and an impedance bandwidth better than 11%, which is much wider than the conventional printed antenna on the same materials. © 2011 IEEE. Source

Ettorre M.,University of Michigan | Ettorre M.,CNRS Institute of Electronics and Telecommunications, Rennes | Grbic A.,University of Michigan
IEEE Transactions on Antennas and Propagation | Year: 2012

The generation of Bessel beams using a leaky radial waveguide is presented. The radial waveguide consists of a capacitive sheet over a ground plane. It supports an azimuthally invariant leaky-wave mode whose normal electric-field component is a truncated, zeroth-order Bessel function. The annular spectrum and nondiffractive extent of the Bessel beam is clearly linked to the complex wavenumber of the leaky-wave mode. The fields inside the radial waveguide are derived using classical vector potential techniques. A vector approach is employed to avoid paraxial approximations of earlier works and the associated limitations on shaping the Bessel beam. Design rules are provided to synthesize a desired propagating Bessel beam. A simple coaxial feed is proposed for the radial waveguide and its input impedance is derived analytically. The analytical results are also validated numerically. The proposed structure and design procedure can be used for generating arbitrary zeroth-order propagating Bessel beams at microwave and millimeter-wave frequencies. © 1963-2012 IEEE. Source

Albani M.,University of Siena | Pavone S.C.,University of Siena | Casaletti M.,University Pierre and Marie Curie | Ettorre M.,CNRS Institute of Electronics and Telecommunications, Rennes
Optics Express | Year: 2014

The focusing capabilities of an inward cylindrical traveling wave aperture distribution and the non-diffractive behaviour of its radiated field are analyzed. The wave dynamics of the infinite aperture radiated field is clearly unveiled by means of closed form expressions, based on incomplete Hankel functions, and their ray interpretation. The non-diffractive behaviour is also confirmed for finite apertures up to a defined limited range. A radial waveguide made by metallic gratings over a ground plane and fed by a coaxial feed is used to validate numerically the analytical results. The proposed system and accurate analysis of nondiffractive Bessel beams launched by inward waves opens new opportunities for planar, low profile beam generators at microwaves, Terahertz and optics. © 2014 Optical Society of America. Source

Chahat N.,CNRS Institute of Electronics and Telecommunications, Rennes | Zhadobov M.,CNRS Institute of Electronics and Telecommunications, Rennes | Sauleau R.,CNRS Institute of Electronics and Telecommunications, Rennes | Ito K.,Chiba University
IEEE Transactions on Antennas and Propagation | Year: 2011

A new compact planar ultrawideband (UWB) antenna designed for on-body communications is presented. The antenna is characterized in free space, on a homogeneous phantom modeling a human arm, and on a realistic high-resolution whole-body voxel model. In all configurations it demonstrates very satisfactory features for on-body propagation. The results are presented in terms of return loss, radiation pattern, efficiency, and E-field distribution. The antenna shows very good performance within the 3-11.2 GHz range, and therefore it might be used successfully for the 3.1-10.6 GHz IR-UWB systems. The simulation results for the return loss and radiation patterns are in good agreement with measurements. Finally, a time-domain analysis over the whole-body voxel model is performed for impulse radio applications, and transmission scenarios with several antennas placed on the body are analyzed and compared. © 2006 IEEE. Source

Muhammad S.A.,CNRS Institute of Electronics and Telecommunications, Rennes | Sauleau R.,CNRS Institute of Electronics and Telecommunications, Rennes | Legay H.,Thales Alenia
IEEE Transactions on Antennas and Propagation | Year: 2012

New configurations of small-size shielded metallic Fabry-Perot (FP) antennas with improved performance over a large frequency band are presented in -band for space missions. The bandwidth enlargement is obtained by stacking two FP cavities of different size, each of them presenting a low quality factor. Their radiating apertures measure around λ 0 and 2 × λ 0, respectively. Concentric corrugations are also introduced between both cavities to control the higher-order modes that are excited systematically in shielded small-size FP antennas due to lateral resonances. The obtained results are compared to those of a single-stage FP cavity antenna with the same aperture size. Several prototypes have been fabricated and measured. An aperture efficiency higher than 70%, a reflection coefficient smaller than -15 dB, and sidelobe levels lower than 20 dB have been obtained experimentally, over a wide frequency band (2.4-2.66 GHz). These characteristics make stacked FP cavity antennas very attractive to replace global coverage horn antennas, or to be used in feed clusters of multiple-beam antennas, especially in - and -bands, where they lead to more compact and less bulky solutions compared to classical feed horns. © 2011 IEEE. Source

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