Showing papers on "Reflector (antenna) published in 2013"

Wireless charging with reflectors

Abstract: A wireless power transmission method may employ pocket forming in combination with one or more reflectors for redirecting the formation of pockets of energy towards one or more locations or electronic devices of interest. A transmitter can be purposely aimed at the reflector which can then redirect the transmitted RF waves towards a receiver embedded or operatively coupled to the electronic device. These reflectors can be installed in the room ceiling, walls, or floor, in relation to the position of the transmitter and the electronic device. Reflectors can be made of metallic materials capable of reflecting RF waves and can exhibit various configurations, shapes, sizes and surface textures, according to the application.

Subreflector of a dual-reflector antenna

Abstract: A subreflector of a dual-reflector antenna comprises a first extremity comprising a convex inner surface, a second extremity adapted for coupling to the extremity of a waveguide, and a body extending between the first extremity and the second extremity The body comprises a first dielectric part having a portion penetrating into the waveguide and a portion outside the waveguide, and a second metallic part comprising a first cylindrical portion, contiguous with the first extremity of the subreflector, whose diameter is greater than the portion outside the waveguide of the first dielectric part, and a second cylindrical portion, adjacent to the first cylindrical portion, extended by a conical portion that penetrates into the first dielectric part The first cylindrical portion features a flat ring-shaped surface that forms an angle less than 90° with the axis of the subreflector so as to face the primary reflector

Low sidelobe reflector antenna with shield

Abstract: A front feed reflector antenna with a dish reflector has a wave guide is coupled to a proximal end of the dish reflector, projecting into the dish reflector along a longitudinal axis. A dielectric block may be coupled to a distal end of the waveguide and a sub-reflector coupled to a distal end of the dielectric block. A shield is coupled to the periphery of the dish reflector. A subtended angle between the longitudinal axis and a line between the focal point and a distal periphery of the shield is 50 degrees or less.

Microwave diode switchable metamaterial reflector/absorber

Abstract: We embed diodes as active circuit elements within a metamaterial to implement a switchable metamaterial reflector/absorber at microwave frequencies. Diodes are placed in series with the unit cells of the metamaterial array. This results in just a pair of control lines to actively tune all the diodes in a metamaterial. Diodes can be tuned on and off to switch the function of the metamaterial between a perfect absorber and a reflector. The design, simulation, and experimental results of a switchable reflector/absorber in 2–6 GHz range are presented.

Mounting hub for antenna

Abstract: An antenna hub for a reflector dish has a frame with a feed aperture. A plurality of feet are coupled to the frame; each of the feet provided with a dish fastener coupling axis normal to a dish surface contacting each of the feet when the reflector dish is seated upon the feet, the feed bore of the reflector dish aligned coaxial with the feed aperture. The frame and feet may be formed via extrusion.

Multi-Band, Wide-Beam, Circularly Polarized, Crossed, Asymmetrically Barbed Dipole Antennas for GPS Applications

Abstract: This communication presents a multi-band, circularly polarized (CP), wide beamwidth, highly efficient antenna for use in global positioning systems (GPS). The primary radiating elements are two crossed printed dipoles, which incorporate a 90° phase delay line realized with a vacant-quarter printed ring to produce the CP radiation and broadband impedance matching. To achieve multiple resonances, each dipole arm is divided into four branches with different lengths, and a printed inductor with a barbed end is inserted in each branch to reduce the radiator size. An inverted, pyramidal, cavity-backed reflector is incorporated with the crossed dipoles to produce a unidirectional radiation pattern with a wide 3-dB axial ratio (AR) beamwidth and a high front-to-back ratio. The multi-band antennas have broad impedance matching and 3-dB AR bandwidths, which cover the GPS L1-L5 bands.

Subreflector of a dual-reflector antenna

Abstract: The reflector unit of the dual reflector antenna comprising a main body extended between a first end, a second end suitable to be coupled to the ends of the waveguide, and a first end and a second end comprising a convex inner surface. The body of claim 1 adjacent to the dielectric portion, and a first end of the sub-reflector and the diameter is larger first cylinder portion, and a first dielectric material than the wave guide outside portion of the first dielectric portion with a section and the wave guide outside part passing through the wave guide and a second metal part comprises a second cylindrical portion adjacent the first cylindrical portion, which is extended by a conical portion extending through the part. The first cylindrical portion is characterized by a surface of the flat ring shape to form an angle of less than 90 ° with the axis of the reflector portion so as to face the main reflector.

Reflectarray antenna system

Abstract: One embodiment describes a reflectarray antenna system. The system includes an antenna feed configured to at least one of transmit and receive a wireless signal occupying a frequency band. The system also includes a reflector comprising a reflectarray. The reflectarray includes a plurality of reflectarray elements, where each of the reflectarray elements includes a dipole element. The dipole element of at least a portion of the plurality of reflectarray elements comprises a crossed-dipole portion and a looped-dipole portion. The plurality of reflectarray elements can be configured to selectively phase-delay the wireless signal to provide the wireless signal as a coherent beam.

Injection moldable cone radiator sub-reflector assembly

Abstract: A dielectric cone radiator sub-reflector assembly for a reflector antenna with a waveguide supported sub-reflector is provided as a unitary dielectric block with a sub-reflector at a distal end. A waveguide transition portion of the dielectric block is dimensioned for insertion coupling into an end of the waveguide. A sub-reflector support portion of the dielectric block and the waveguide transition portion provided with a plurality of longitudinal ribs and grooves coaxial with a longitudinal axis of the assembly; the longitudinal grooves open to a proximal end of the dielectric block. The unitary dielectric block may be manufactured as a single contiguous monolithic portion of dielectric material via injection molding.

Triple-Band Unidirectional Circularly Polarized Hexagonal Slot Antenna With Multiple L-Shaped Slits

Abstract: The design of a triple-band circularly polarized hexagonal slot antenna with L-shaped slits is presented in this study. By adding three L-shaped slit arms to the hexagonal slot, circularly polarized radiation is achieved at three different frequencies. The proposed slot antenna is excited by a simple tapered microstrip feeding line. A conducting reflector is also used to enhance the antenna gain. The measured -10 dB reflection bandwidths are 33.16% (3.22-4.5 GHz) and 22.72% (4.76-5.98 GHz). The measured 3 dB axial ratio bandwidths for the triple bands are 1.7%, 3.86%, and 5.23%, respectively. The measured peak gains within the 3 dB axial ratio bands are 5.5 dBic, 4.63 dBic, and 6.77 dBic.

Improving limited-view photoacoustic tomography with an acoustic reflector

Abstract: The versatility and real-time imaging capability of commercial linear array transducers make them widely used in clinical ultrasound and photoacoustic imaging. However, they often suffer from limited detection view. For instance, acoustic waves traveling at a grazing angle to the transducer surface are difficult to detect. In this letter, we propose a simple and easy approach to ameliorate this problem by using a 45-deg acoustic reflector. The reflector forms a virtual array that is perpendicular to the physical array, thereby doubling the detection coverage. The improvement in image quality in photoacoustic tomography was demonstrated through a hair phantom, a leaf skeleton phantom, and an ex vivo mouse ear experiment.

Active antenna system (AAS) radio frequency (RF) module with heat sink integrated antenna reflector

Abstract: On-board heat dissipation can be achieved in radio frequency (RF) modules by integrating a heat sink into the RF module's antenna reflector. Said integration achieves a compact and aesthetically pleasing RF module design that reduces the overall footprint of modular active antenna systems (AASs). Embodiment antenna reflectors include portions that are perforated and/or exposed to free flowing air to provide enhanced heat dissipation capability.

A Compact Dual-Band Pattern Diversity Antenna by Dual-Band Reconfigurable Frequency-Selective Reflectors With a Minimum Number of Switches

Abstract: A novel compact dual-band pattern diversity antenna is proposed. Dual-band reconfigurable frequency-selective reflectors are designed and applied to form a right-angle corner reflector antenna with reconfigurable patterns. With only one switch, the reconfigurable frequency-selective reflector can be controlled to be transmissive or reflective to vertically polarized waves at 2.45 and 5.25 GHz. By changing the combinations of the switch states, multiple patterns can be obtained. A dual-band feeding antenna designed via using the coupling effects is made to achieve well-matching conditions in all circumstances corresponding to various switch states at both frequencies. The measured results show good agreement with the calculated ones and demonstrate good pattern diversity virtues.

Digital holographic interferometry with CO2 lasers and diffuse illumination applied to large space reflectors metrology

Abstract: Digital holographic interferometry in the long-wave infrared domain has been developed by combining a CO2 laser and a microbolometer array The long wavelength allows large deformation measurements, which are of interest in the case of large space reflectors undergoing thermal changes when in orbit We review holography at such wavelengths and present some specific aspects related to this spectral range on our measurements For the design of our digital holographic interferometer, we studied the possibility of illuminating specular objects by a reflective diffuser We discuss the development of the interferometer and the results obtained on a representative space reflector, first in the laboratory and then during vacuum cryogenic test

Design of Engineered Reflectors for Radar Cross Section Modification

Abstract: A technique is proposed for the design of engineered reflectors consisting of doubly periodic arrays printed on thin grounded dielectric substrates that reflect an incoming wave from a given incoming direction to a predetermined outgoing direction. The proposed technique is based on a combination of Floquet theory for propagation in periodic structures and reflect-array principles. A flat surface designed to reflect a TE polarized wave incident at 45° back in the direction of the impinging signal at 14.7 GHz is employed as an example. By means of full-wave simulations, it is demonstrated that the monostatic RCS of a finite reflector is comparable with the specular RCS of a metallic mirror of the same dimensions. It is further shown that comparably high monostatic RCS values are obtained for angles of incidence in the 30°-60° range, which are frequency dependent and thus open opportunities for target localization. A prototype array is fabricated and experimentally tested for validation. The proposed solution can be used to modify the radar cross section of a target. Other potential applications are also discussed.

Design of an optical element forming an axial line segment for efficient LED lighting systems

Abstract: An LED optical element is proposed as an alternative to cold-cathode fluorescent lamps. The optical element generates two symmetric uniformly illuminated line segments on the diffuse reflector. The illuminated segments then act as secondary linear light sources. The calculation of the optical element is reduced to the integration of the system of two explicit ordinary differential equations. The results of the simulation of an illumination system module consisting of a set of optical elements generating a set of line segments on the surface of the diffuse reflector are presented. The elements are located directly on the surface of the reflector. The simulation results demonstrate the uniform illumination of a rectangular area at a distance of 30–40 mm from the light source plane. The lighting efficiency of the designed system exceeds 83%.

Wide field-of-view reflector and method of designing and making same

Abstract: A system and method for designing and using freeform reflectors to collect images of a wide angle field-of-view scene is provided. A freeform reflector may enable a wide angle field-of-view to be collected in an unwarped and unwrapped manner such that computer processing may be eliminated. Furthermore, the use of a freeform reflector allows for larger areas of an image sensor chip to be used, thereby providing higher resolution images. Because freeform reflectors may be configured to map a scene onto the image sensor chip in a scalar and mathematically correct manner, output images may be directly displayed from the image sensor chip. Wide angle field-of-view imaging systems, such as surveillance, alarm, and projector system, may utilize freeform reflectors as provided herein.

Thermal Management for Light Emitting Diode Fixture

Abstract: A recessed light fixture includes an LED module, which includes a single LED package that is configured to generate all light emitted by the recessed light fixture. For example, the LED package can include multiple LEDs mounted to a common substrate. The LED package can be coupled to a heat sink for dissipating heat from the LEDs. The heat sink can include a core member. A reflector housing may be coupled to the heat sink and configured to receive a reflector. The reflector can have any geometry, such as a bell-shaped geometry including two radii of curvature that join together at an inflection point. An optic coupler can be coupled to the reflector housing and configured to cover electrical connections at the substrate and to guide light emitted by the LED package.

Phase-compensated metasurface for a conformal microwave antenna

Abstract: The in-phase radiation from a conformal metamaterial surface is numerically and experimentally reported. The LC-resonant metasurface is composed of a simultaneously capacitive and an inductive grid constituted by copper strips printed on both sides of a dielectric board. The metasurface is designed to fit a curved surface by modifying its local phase. The latter phase-compensated metasurface is used as a reflector in a conformal Fabry-Perot resonant cavity designed to operate at microwave frequencies. Far-field measurements performed on a fabricated prototype allow showing the good performances of such a phase-compensated metasurface in restoring in-phase emissions from the conformal surface and producing a directive emission in the desired direction.

The Circular Eleven Antenna: A New Decade-Bandwidth Feed for Reflector Antennas With High Aperture Efficiency

Abstract: Future ultra-wideband (UWB) radio telescopes require UWB feeds for reflector antennas, and many new UWB feed technologies have gained substantial progress to satisfy the tough specifications for future radio telescope projects, such as the square kilometer array (SKA). It has been noticed that, different from traditional narrow-band horn feeds, all UWB feeds are non-BOR (Body of Revolution) antennas. Therefore, BOR1 efficiency becomes an important characterization for the modern UWB feed technologies. We present a novel circular Eleven feed, constructed of “circularly” curved folded dipoles printed on flat circuit boards, in order to have high BOR1 efficiency at a low manufacture cost. The Genetic Algorithm (GA) optimization scheme has been applied to the design for achieving a low reflection coefficient. Simulated and measured results show that the circular Eleven feed has a reflection coefficient below -6 dB over 1.6-14 GHz and below -10 dB over 78% of the band, and an aperture efficiency higher than 60% over 1-10 GHz and 50% up to 14 GHz.

Design of a Broadband Cosecant Squared Pattern Reflector Antenna Using IWO Algorithm

Abstract: A cosecant squared pattern reflector antenna fed by a pyramidal double-ridged horn for 2-18 GHz is presented. Invasive weed optimization (IWO) algorithm is used for synthesizing the point source doubly curved reflector antenna. IWO method makes antenna synthesis flexible to achieve extra desired features such as low side lobe level (SLL) and low ripples in the shaped beam region. The simulation results via FEKO software package further prove the validity and versatility of this technique for solving reflector synthesis problems. In addition, experimental investigations are conducted to understand the complete reflector antenna system behaviors. Good agreement between the simulation and measurement has been achieved. The ripple in the cosecant squared region and the SLL is less than 1.5 dB and 25 dB, respectively. Based on the obtained results, the proposed reflector antenna can be used in broadband surveillance-search radar systems.

Design and Optimization of a Compact Wideband Hat-Fed Reflector Antenna for Satellite Communications

Abstract: We present a new design of the hat-fed reflector antenna for satellite communications, where a low reflection coefficient, high gain, low sidelobes and low cross-polar level are required over a wide frequency band. The hat feed has been optimized by using the Genetic Algorithm through a commercial FDTD solver, QuickWave-V2D, together with an own developed optimization code. The Gaussian vertex plate has been applied at the center of the reflector in order to improve the reflection coefficient and reduce the far-out sidelobes. A parabolic reflector with a ring-shaped focus has been designed for obtaining nearly 100% phase efficiency. The antenna's reflection coefficient is below -17 dB and the radiation patterns satisfy the M-x standard co- and cross-polar sidelobe envelopes for satellite ground stations over a bandwidth of 30%. A low-cost monolayer radome has been designed for the antenna with satisfactory performance. The simulations have been verified by measurements; both of them are presented in the paper.

A constant gain ultra-wideband antenna with a multi-layer frequency selective surface

Abstract: An ultra-wideband (UWB) antenna with a novel multi-layer frequency selective surface (FSS) reflector is presented. A significant enhancement in the gain has been achieved in a low profile design while maintaining the excellent impedance bandwidth of the UWB antenna. The average peak gain of the antenna has been increased from 4 dBi to 9.3 dBi as a consequence of the use of the FSS reflector. More importantly the gain variation within the frequency range from 3 GHz to 15 GHz is only +/-0.5 dB. This is a significant improvement from §2 dB gain variation of the UWB slot antenna without the reflector. This optimized FSS re°ector provides the flexibility of mounting a planar antenna close to conducting bodies, including screens and cases

Improved fundamental harmonic current distribution in a klystron-like relativistic backward wave oscillator by two pre-modulation cavities

Abstract: In a klystron-like relativistic backward wave oscillator, the velocity modulation is mainly obtained from the resonant reflector. By introducing two pre-modulation cavities between the input cavity and the resonant reflector, the amplitude and phase of density modulation can be adjusted relatively independently, to ensure an improved fundamental harmonic current distribution. Two peaks of harmonic current with high modulation coefficient of 1.2 appear in the second slow wave structure and the dual-cavity extractor and result in large beam energy losses in both regions. Particle-in-cell simulations show that a microwave with power of 11.5 GW and efficiency of 57% can be obtained.

Accurate Beam Prediction Through Characteristic Basis Function Patterns for the MeerKAT/SKA Radio Telescope Antenna

Abstract: A novel beam expansion method is presented that requires employing only a few Characteristic Basis Function Patterns (CBFPs) for the accurate prediction of antenna beam patterns. The method is applied to a proposed design of the MeerKAT/SKA radio telescope, whose antenna geometry is subject to small deformations caused by mechanical or gravitational forces. The resulting deformed pattern, which is affected in a nonlinear fashion by these deformations is then sampled in a few directions only after which the interpolatory CBFPs accurately predict the entire beam shape (beam calibration). The procedure for generating a set of CBFPs—and determining their expansion coefficients using a few reference point sources in the sky—is explained, and the error of the final predicted pattern relative to the actual pattern is examined. The proposed method shows excellent beam prediction capabilities, which is an important step forward towards the development of efficient beam calibration methods for future imaging antenna systems.

Deployable Satellite Reflector with a Low Passive Intermodulation Design

Abstract: A passive intermodulation modulation reducing structure for a multicarrier reflector system, including a plurality of flexible reflector gores, each gore having thin layer of conductive metal, a first layer of dielectric material laminated to one face of the conductive metal, and a second layer of dielectric material laminated to opposite face of the conductive metal. Capacitive coupling joins the reflector's RF components. The structure can be a deployable parabolic reflector for a satellite antenna.

Directional multi-band antenna employing frequency selective surfaces

Abstract: Proposed is a concept of a directional multi-band antenna employing frequency selective surfaces (FSSs). To confirm the feasibility of the concept, the proposal is implemented by combining a metal reflector, two FSSs that act as frequency filters, and a multi-band radiator. The proposed triple-band antenna can radiate at 800 MHz (the metal reflector or FSS 1), 2 GHz (FSS 2), and 4 GHz (FSS 3). FSS 2 passes waves at one frequency band (800 MHz) and reflects all other bands, and FSS 3 passes waves at two frequency bands (800 MHz/2 GHz) and reflects all other bands. Beam control is easy since all that is needed is to change FSS size and/or the distance between the radiator and metal reflector/FSS. Electromagnetic field simulations and measurements demonstrate good directivity in the frequency bands of 800 MHz, 2 GHz and 4 GHz.