Abstract: One subject of the present invention is an electromagnetic-wave-absorbing composite material comprising a carrier matrix (11) and an electromagnetic-wave-absorbing filler (12). According to the invention, the carrier matrix (11) is a cork matrix, which is formed of particles the equivalent diameter Del of which is comprised between 10 ?m and 5 mm, and the composite material (1) has a real permittivity higher than 1.2 and a dielectric loss tangent tan ? higher than 0.1. Another subject of the present invention is a method for producing such a material, and the use of this material as an absorber, in particular in an anechoic chamber, or as a radar absorber in stealth devices, or even to improve the electromagnetic compatibility of electronic devices.

Abstract: One subject of the present invention is an electromagnetic-wave-absorbing composite material comprising a carrier matrix (11) and an electromagnetic-wave-absorbing filler (12). According to the invention, the carrier matrix (11) is a cork matrix, which is formed of particles the equivalent diameter Del of which is comprised between 10 ?m and 5 mm, and the composite material (1) has a real permittivity higher than 1.2 and a dielectric loss tangent tan ? higher than 0.1. Another subject of the present invention is a method for producing such a material, and the use of this material as an absorber, in particular in an anechoic chamber, or as a radar absorber in stealth devices, or even to improve the electromagnetic compatibility of electronic devices.

Abstract: The present invention relates to a circularly polarized directional helical antenna that is capable of being used in RFID devices and more particularly in RFID readers. The antenna is intended to transmit or receive signals in a predetermined frequency band, ? being the wavelength associated with the minimum frequency of the predetermined frequency band. It includes a helicoidal radiating element made of conductive material extending along a longitudinal axis (A) and the axial length (H) of which is less than the wavelength ?, and a cavity made of conductive material having an open end and a closed end and having an axis of symmetry that coincides with the longitudinal axis of the radiating element, at least one lower portion of the radiating element being arranged inside the cavity so that its lower end is in contact with the closed end of the cavity.

Abstract: The present invention relates to a circularly polarized directional helical antenna that is capable of being used in RFID devices and more particularly in RFID readers. The antenna is intended to transmit or receive signals in a predetermined frequency band, ? being the wavelength associated with the minimum frequency of the predetermined frequency band. It includes a helicoidal radiating element made of conductive material extending along a longitudinal axis (A) and the axial length (H) of which is less than the wavelength ?, and a cavity made of conductive material having an open end and a closed end and having an axis of symmetry that coincides with the longitudinal axis of the radiating element, at least one lower portion of the radiating element being arranged inside the cavity so that its lower end is in contact with the closed end of the cavity.

Abstract: A helical antenna comprising at least one helix which is formed by at least two radiating wires. According to the invention, at least one of said radiating wires is associated with a parasitic wire having a width which is less than or equal to the radiating wire(s), such as to broaden the bandwidth of the antenna.

Abstract: A helical antenna comprising at least one helix which is formed by at least two radiating wires. According to the invention, at least one of said radiating wires is associated with a parasitic wire having a width which is less than or equal to the radiating wire(s), such as to broaden the bandwidth of the antenna.

Abstract: A helical antenna includes at least a helix consisting of at least two radiating strands, at least one of the strands consisting of at least two segments, the winding angles of at least two of the segments being different and randomly or pseudo-randomly determined with global optimising means.

Abstract: The invention concerns a helical antenna, comprising at least a helix consisting of at least two radiating strands, at least one of said strands consisting of at least two segments, the winding angles of at least two of said segments being different and randomly or pseudo-randomly determined with global optimising means.

Abstract: The invention relates to a helix antenna with integrated duplexing means comprising two decoupled coaxial helices, each formed by radiating strands (111 to 114) printed on a substrate, each of the helices being associated with an independent and miniaturized structure (12, 13, 14) for the wideband supply of the radiating strands, the supply structures being printed on the corresponding substrate and comprising at least one hybrid coupler (12, 13, 14) made out of semi-localized elements so as to reduce the dimensions thereof. Advantageously, the helices are wound in opposite directions of winding (17) and their points of excitation are offset with respect to each other, in a plane perpendicular to the axis of the helices. Corresponding methods of manufacture are used to form the helix antenna.

Abstract: A resonant helix antenna comprising at least one helix formed by at least two radiating strands (111 to 114) printed on a substrate. This antenna comprises a miniaturised structure for the wideband supply of the radiating strands that is printed on the substrate and comprises at least one hybrid coupler made out of semi-localised elements so as to reduce the dimensions thereof. In the case of a quadrifilar helix, formed by four radiating strands, the supply structure comprises three hybrid couplers, for example in the form of a first 180° hybrid coupler (12) associating a supply input and/or output (17) of the antenna with two intermediate outputs and/or inputs (18, 19) phase-shifted by 180° and two 90° hybrid couplers (13, 14) each associating one of the intermediate outputs and/or inputs of the hybrid coupler with one of the ends of two of the radiating strands.