Showing papers on "Antenna (radio) published in 2009"

Packaging and details of a wireless power device

Abstract: A wireless power system includes a power source, power receiver, and components thereof. The system can also include a parasitic antenna that can improve the coupling to the power source in various modes. The antenna can have both a variable capacitor and a variable inductor, and both of those can be changed in order to change characteristics of the matching.

Antenna-on-Chip and Antenna-in-Package Solutions to Highly Integrated Millimeter-Wave Devices for Wireless Communications

Abstract: Antenna-on-chip (AoC) and antenna-in-package (AiP) solutions are studied for highly integrated millimeter-wave (mmWave) devices in wireless communications. First, the background, regulations, standard, and applications of 60-GHz wireless communications are briefly introduced. Then, highly integrated 60-GHz radios are overviewed as a basis for the link budget analysis to derive the antenna gain requirement. Next, in order to have deep physical insight into the AoC solution, the silicon substrate's high permittivity and low resistivity effects on the AoC efficiency are examined. It is shown that the AoC solution has low efficiency, less than 12% due to large ohmic losses and surface waves, which requires the development of techniques to improve the AoC efficiency. After that, the AiP solution and associated challenges such as how to realize low-loss interconnection between the chip and antenna are addressed. It is shown that wire-bonding interconnects, although inferior to the flip-chip, are still feasible in the 60-GHz band if proper compensation schemes are utilized. An example of the AiP solution in a low-temperature cofired ceramic (LTCC) process is presented in the 60-GHz band showing an efficiency better than 90%. A major concern with both AoC and AiP solutions is electromagnetic interference (EMI), which is also discussed. Finally, the systems level pros and cons of both AoC and AiP solutions are highlighted from the electrical and economic perspectives for system designers.

Discrete cyclic porphyrin arrays as artificial light-harvesting antenna.

Abstract: The importance of photosynthesis has driven researchers to seek ways to mimic its fundamental features in simplified systems. The absorption of a photon by light-harvesting (antenna) complexes made up of a large number of protein-embedded pigments initiates photosynthesis. Subsequently the many pigments within the antenna system shuttle that photon via an efficient excitation energy transfer (EET) until it encounters a reaction center. Since the 1995 discovery of the circularly arranged chromophoric assemblies in the crystal structure of light-harvesting antenna complex LH2 of purple bacteria Rps. Acidophila, many designs of light-harvesting antenna systems have focused on cyclic porphyrin wheels that allow for efficient EET. In this Account, we review recent research in our laboratories in the synthesis of covalently and noncovalently linked discrete cyclic porphyrin arrays as models of the photosynthetic light-harvesting antenna complexes. On the basis of the silver(I)-promoted oxidative coupling strate...

Controlling the near-field oscillations of loaded plasmonic nanoantennas

Abstract: Optical and infrared antennas 1–6 enable a variety of cuttingedge applications ranging from nanoscale photodetectors 7 to highly sensitive biosensors 8 All these applications critically rely on the optical near-field interaction between the antenna and its ‘load’ (biomolecules or semiconductors) However, it is largely unexplored how antenna loading affects the near-field response Here, we use scattering-type near-field microscopy to monitor the evolution of the near-field oscillations of infrared gap antennas progressively loaded with metallic bridges of varying size Our results provide direct experimental evidence that the local near-field amplitude and phase can be controlled by antenna loading, in excellent agreement with numerical calculations By modelling the antenna loads as nanocapacitors and nanoinductors 9–11 , we show that the change of near-field patterns induced by the load can be understood within the framework of circuit theory Targeted antenna loading provides an excellent means of engineering complex antenna configurations in coherent control applications 12 , adaptive nano-optics 13 and metamaterials 14 Optical and infrared antennas based on metal nanostructures allow for efficient conversion of propagating light into nanoscale confined and strongly enhanced optical fields, and vice versa 1–5,15

Wireless power transmission for electronic devices

Abstract: Exemplary embodiments are directed to wireless power transfer. A wireless power receiver includes a receive antenna for coupling with a transmit antenna of transmitter generating a magnetic near field. The receive antenna receives wireless power from the magnetic near field and includes a resonant tank and a parasitic resonant tank wirelessly coupled to the resonant tank. A wireless power transmitter includes a transmit antenna for coupling with a receive antenna of a receiver. The transmit antenna generates a magnetic near field for transmission of wireless power and includes a resonant tank and a parasitic resonant tank coupled to the resonant tank.

Method and apparatus for adaptive tuning of wireless power transfer

Abstract: Exemplary embodiments are directed to wireless power transfer. A transmit antenna generates an electromagnetic field at a resonant frequency of to create a coupling-mode region within a near field of the transmit antenna. A receive antenna receives the resonant frequency when it is within the coupling-mode region and resonates substantially near the resonant frequency. One, or both, of the transmit and receive antennas are tunable antennas that can be adaptively tuned. The adaptive tuning is accomplished by detecting a mismatch at the tunable antenna and generating a mismatch signal responsive to a voltage standing wave ratio at the tunable antenna. A resonance characteristic of the tunable antenna can be modified by adjusting a capacitance of a variable capacitor network connected to the tunable antenna.

Wireless power transmission for portable wireless power charging

Abstract: Exemplary embodiments are directed to wireless power transfer. A portable wireless power charger includes an antenna configured to generate a magnetic near-field for coupling of wireless power to a wireless powered device including a receiver. The antenna is substantially disposed around the perimeter of the charging pad. The portable wireless power charger further includes a feeder cable for coupling the input power to the charging pad.

Ultrawideband MIMO/Diversity Antennas With a Tree-Like Structure to Enhance Wideband Isolation

Abstract: A compact printed ultrawideband (UWB) multiple-input multiple-output (MIMO)/diversity antenna system (of two elements) with a size of 35 × 40 mm2 operating at a frequency range of 3.110.6 GHz is proposed. The wideband isolation can be achieved through a tree-like structure on the ground plane. The effectiveness of the tree-like structure is analyzed. Measured S-parameters show that the isolation is better than -16 dB (-20 dB in most of the band) across the UWB of 3.110.6 GHz. The radiation patterns, gain, and envelope correlation coefficient are also measured. The proposed antenna is suitable for some portable MIMO/diversity applications.

Wireless power transfer for vehicles

Abstract: Exemplary embodiments are directed to wireless power transfer. A power transmitting device is attached to an existing vehicle item or is embedded in a vehicle element. The power transmitting device includes a transmit antenna to wirelessly transfer power to a receive antenna by generating a near-field radiation within a coupling-mode region. An amplifier applies a driving signal to the transmit antenna. A presence detector may detect a presence of a receiver device within the coupling-mode region. The presence detector may also detect a human presence. An enclosed compartment detector may detect when the vehicle element is in a closed state. A power output may be adjusted in response to the closed state, the presence of a receiver device, and the presence of a human.

Wireless power for charging devices

Abstract: Exemplary embodiments are directed to wireless power. A host device peripheral may comprise a wireless power charging apparatus, which may include transmit circuitry and at least one antenna coupled to the transmit circuitry. The at least one antenna may be configured to wirelessly transmit power within an associated near-field region. Additionally, the host device peripheral may be configured to couple to a host device.

Bidirectional wireless power transmission

Abstract: Exemplary embodiments are directed to wireless power transfer. A wireless power transceiver and device comprise an antenna including a parallel resonator configured to resonate in response to a substantially unmodulated carrier frequency. The wireless power transceiver further comprises a bidirectional power conversion circuit coupled to the parallel resonator. The bidirectional power conversion circuit is reconfigurable to rectify an induced current received at the antenna into DC power and to induce resonance at the antenna in response to DC power.

Wireless power transfer in public places

Abstract: Exemplary embodiments are directed to public wireless-power-transmission. A device disposed in or on a publicly placed structure and a user neighboring device includes a repeater antenna with a loop antenna and a capacitive element. The public wireless-power-transmitting device includes a transmit antenna to wirelessly transfer power by generating a near-field radiation at a resonant frequency within a coupling-mode region and an amplifier for driving the transmit antenna. When in the coupling-mode region, the repeater antenna couples with the near-field radiation generated by the transmit antenna and develops an enhanced coupling-mode region about the repeater antenna with a repeated near-field radiation that is stronger than the near-field radiation of the transmit antenna within the enhanced coupling-mode region. Power may be wirelessly transferred from the enhanced coupling-mode region to a receiver device including a receive antenna.

Systems and methods relating to multi-dimensional wireless charging

Abstract: Exemplary methods and systems related to wireless charging are disclosed. In an exemplary embodiment, a plurality of transmit antennas are used, wherein at least one transmit antenna of the plurality of transmit antennas is configured to be oriented in a different plane than at least one other transmit antenna of the plurality of transmit antennas. Furthermore, each transmit antenna of the plurality of transmit antennas is configured for transmitting power within an associated near-field.

Non-Foster Impedance Matching of Electrically-Small Antennas

Abstract: Electrically-small antennas present high-Q impedances characterized by large reactances and small radiation resistances. For such antennas, the effectiveness of passive matching is severely limited by gain-bandwidth theory, which predicts narrow bandwidths and/or poor gain. With receivers, the inability to resolve this impedance mismatch results in poor signal-to-noise (S/N) ratio, as compared to using a full-size antenna. With transmitters, the consequence is poor power efficiency. However, in many applications full-size antennas are impractical, and a means is required to effectively match their electrically-small counterparts. This paper presents the technique of non-Foster impedance matching, which employs active networks of negative inductors and capacitors to bypass the restrictions of gain-bandwidth theory. We first review the origins and development of non-Foster impedance matching, and then present experimental results for the non-Foster impedance matching of electrically-small dipoles and monopoles. For receivers, our best measurements on the antenna range demonstrate up to 20 dB improvement in S/N over 20-120 MHz; for transmitters, we show a power efficiency improvement which exceeds a factor of two over an 5% bandwidth about 20 MHz with an average signal power of 1 W to the radiation resistance.

Tracking receiver devices with wireless power systems, apparatuses, and methods

Abstract: Exemplary embodiments are directed to communicating information relating to wireless charging. A power transmitting system includes a host device with a transmit antenna. A communication interface conveys receiver information, which includes unique identifier information, from a receiver device to the host device. A controller on the host device monitors and processes the receiver information to generate notification information, which is presented to a user on a user-perceivable notifier. The transmit antenna generates an electromagnetic field at a resonant frequency to create a coupling-mode region within a near-field of the transmit antenna. The system can detect a presence of a receiver device with a receive antenna that is in the coupling-mode region and process a request for power from the receiver device. The system can also notify a user when a host device is leaving a designated region and whether the host device includes expected receiver devices.

Optical antenna thermal emitters

Abstract: Optical antennas are a critical component in nanophotonics research1 and have been used to enhance nonlinear2,3 and Raman4 cross-sections and to make nanoscale optical probes5. In addition to their ‘receiving’ properties, optical antennas can operate in ‘broadcasting’ mode, and have been used to modify the emission rate6 and direction7 of individual molecules. In these applications the antenna must operate at frequencies given by existing light emitters. Using thermal excitation of optical antennas, we bypass this limitation and realize emitters at infrared frequencies where sources are less readily available. Specifically, we show that the thermal emission from a single SiC whisker antenna is attributable to well-defined, size-tunable Mie resonances8. Furthermore, we derive a fundamental limit on the antenna emittance and argue theoretically that these structures are nearly ideal black-body antennas. Combined with advancing progress in antenna design, these results could lead to optical antenna emitters operating throughout the infrared frequency range. Single SiC whiskers can be made into infrared emitters by thermal excitation. The broadband thermal emission is coupled to the electromagnetic resonances of the whisker, allowing relatively narrowband emission at infrared frequencies. The emission frequency can be tuned by adjusting the size of the whiskers.

Conductive Inkjet-Printed Antennas on Flexible Low-Cost Paper-Based Substrates for RFID and WSN Applications

Abstract: In this paper, a review of the authors' work on inkjet-printed flexible antennas, fabricated on paper substrates, is given. This is presented as a system-level solution for ultra-low-cost mass production of UHF radio-frequency identification (RFID) tags and wireless sensor nodes (WSN), in an approach that could be easily extended to other microwave and wireless applications. First, we discuss the benefits of using paper as a substrate for high-frequency applications, reporting its very good electrical/dielectric performance up to at least 1 GHz. The RF characteristics of the paper-based substrate are studied by using a microstrip-ring resonator, in order to characterize the dielectric properties (dielectric constant and loss tangent). We then give details about the inkjet-printing technology, including the characterization of the conductive ink, which consists of nano-silver particles. We highlight the importance of this technology as a fast and simple fabrication technique, especially on flexible organic (e.g., LCP) or paper-based substrates. A compact inkjet-printed UHF ldquopassive RFIDrdquo antenna, using the classic T-match approach and designed to match the IC's complex impedance, is presented as a demonstration prototype for this technology. In addition, we briefly touch upon the state-of-the-art area of fully-integrated wireless sensor modules on paper. We show the first-ever two-dimensional sensor integration with an RFID tag module on paper, as well as the possibility of a three-dimensional multilayer paper-based RF/microwave structure.

Basic experimental study on helical antennas of wireless power transfer for Electric Vehicles by using magnetic resonant couplings

Abstract: Wireless power transfer is required for the diffusion of Electric Vehicles (EVs) because it makes possible the process of automatically charging EVs The technology of wireless power transfer requires three main elements: large air gaps, high efficiency and a large amount of power Though, there has been no such technology, recently, the technology of electromagnetic resonant couplings was proposed and named WiTricity With this technology there are large air gaps, high efficiency and large amounts of power In this paper, the feasibility of wireless power transfer for EVs by electromagnetic resonance coupling is studied We studied small sized antennas that can be equipped on the bottom of a vehicle and we studied the electrical characteristics of the antenna with equivalent circuits, electromagnetic analysis and experimentation The length of the air gaps between a transmitting antenna and a receiving antenna affect resonance frequencies The resonance frequency changes from two to one depending on the length of the air gap Until a certain distance, maximum efficiencies are not changed Large air gaps are weak couplings In a weak coupling at resonance, magnetic resonance couplings can transfer energy with high efficiency The specification results at high power are proposed In this paper, the feasibility of wireless power transfer with large air gaps and high efficiency by small sized antennas that can be equipped on the bottom of EVs is proposed

Ionospheric calibration of low frequency radio interferometric observations using the peeling scheme I. Method description and first results

Abstract: Calibration of radio interferometric observations becomes increasingly difficult towards lower frequencies. Below ?300 MHz, spatially variant refractions and propagation delays of radio waves traveling through the ionosphere cause phase rotations that can vary significantly with time, viewing direction and antenna location. In this article we present a description and first results of SPAM (Source Peeling and Atmospheric Modeling), a new calibration method that attempts to iteratively solve and correct for ionospheric phase errors. To model the ionosphere, we construct a time-variant, 2-dimensional phase screen at fixed height above the Earth’s surface. Spatial variations are described by a truncated set of discrete Karhunen-Loeve base functions, optimized for an assumed power-law spectral density of free electrons density fluctuations, and a given configuration of calibrator sources and antenna locations. The model is constrained using antenna-based gain phases from individual self-calibrations on the available bright sources in the field-of-view. Application of SPAM on three test cases, a simulated visibility data set and two selected 74 MHz VLA data sets, yields significant improvements in image background noise (5–75 percent reduction) and source peak fluxes (up to 25 percent increase) as compared to the existing self-calibration and field-based calibration methods, which indicates a significant improvement in ionospheric phase calibration accuracy.

Blockage and directivity in 60 GHz wireless personal area networks: from cross-layer model to multihop MAC design

Abstract: We present a cross-layer modeling and design approach for multigigabit indoor wireless personal area networks (WPANs) utilizing the unlicensed millimeter (mm) wave spectrum in the 60 GHz band. Our approach accounts for the following two characteristics that sharply distinguish mm wave networking from that at lower carrier frequencies. First, mm wave links are inherently directional: directivity is required to overcome the higher path loss at smaller wavelengths, and it is feasible with compact, low-cost circuit board antenna arrays. Second, indoor mm wave links are highly susceptible to blockage because of the limited ability to diffract around obstacles such as the human body and furniture. We develop a diffraction-based model to determine network link connectivity as a function of the locations of stationary and moving obstacles. For a centralized WPAN controlled by an access point, it is shown that multihop communication, with the introduction of a small number of relay nodes, is effective in maintaining network connectivity in scenarios where single-hop communication would suffer unacceptable outages. The proposed multihop MAC protocol accounts for the fact that every link in the WPAN is highly directional, and is shown, using packet level simulations, to maintain high network utilization with low overhead.

Characterization of On-Body Communication Channel and Energy Efficient Topology Design for Wireless Body Area Networks

Abstract: Wireless body area networks (WBANs) offer many promising new applications in the area of remote health monitoring. An important element in the development of a WBAN is the characterization of the physical layer of the network, including an estimation of the delay spread and the path loss between two nodes on the body. This paper discusses the propagation channel between two half-wavelength dipoles at 2.45 GHz, placed near a human body and presents an application for cross-layer design in order to optimize the energy consumption of different topologies. Propagation measurements are performed on real humans in a multipath environment, considering different parts of the body separately. In addition, path loss has been numerically investigated with an anatomically correct model of the human body in free space using a 3-D electromagnetic solver. Path loss parameters and time-domain channel characteristics are extracted from the measurement and simulation data. A semi-empirical path loss model is presented for an antenna height above the body of 5 mm and antenna separations from 5 cm up to 40 cm. A time-domain analysis is performed and models are presented for the mean excess delay and the delay spread. As a cross-layer application, the proposed path loss models are used to evaluate the energy efficiency of single-hop and multihop network topologies.

Receive antenna arrangement for wireless power

Abstract: Exemplary embodiments are directed to wireless charging. An electronic device may comprise at least one receive antenna integrated within an electronic device and configured to receive wireless power from a wireless transmit antenna. Further, the at least one receive antenna may be spaced from each conductive component within the electronic device having a clearance therebetween adapted to enable formation of a magnetic field around the loop conductor.

Surface wave antenna mountable on existing conductive structures

Abstract: What is disclosed is a surface wave antenna configured to install on an electrically conductive structure. The surface wave antenna includes a first portion comprising a conductive element and an attachment element, and a second portion comprising a conductive element and an attachment element. The conductive element of the first portion and the conductive element of the second portion are configured to each form a conductive longitudinal portion of a horn receive element, and the attachment elements are configured to conductively couple the conductive elements together to form the horn receive element. The surface wave antenna also includes a dipole element comprising a first transmit element and a second transmit element. The surface wave antenna also includes a mounting element comprising a first dielectric mount and a second dielectric mount.

Basic Properties and Design Principles of UWB Antennas Selection of suitable antennas from the many existing types, based on understanding their characteristics, is essential for effective ultrawide-band system design.

Abstract: Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advan- tages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.

Development of Low Profile Cavity Backed Crossed Slot Antennas for Planar Integration

Abstract: Single fed low profile cavity backed crossed slot antennas for dual frequency dual linear polarization and circular polarization applications are first presented in this paper. By employing the substrate integrated waveguide (SIW) technique in the antenna designs, the low profile backed cavity structure can be realized by using only a single layer of low cost printed circuit board (PCB) substrate. A single grounded coplanar waveguide (GCPW) is employed as the feeding element to excite the TE 120 and TE 210 modes in the SIW cavity. A crossed slot structure is used as the radiating element in order to radiate the desired dual linearly or circularly polarized wave. From the measurement results, it is seen that these novel antennas retain the advantages of conventional metallic cavity backed antennas, including high gain, high front-to-back ratio (FTBR), and low cross polarization level (CPL). Furthermore, the proposed antennas also possess the advantages of low profile, light weight, low fabrication cost, and easy integration with planar circuits.

Frequency-reconfigurable antennas for multiradio wireless platforms

Abstract: Looking to increase the functionality of current wireless platforms and to improve their quality of service, we have explored the merits of using frequency-reconfigurable antennas as an alternative for multiband antennas. Our study included an analysis of various reconfigurable and multiband structures such as patches, wires, and combinations. Switches, such as radio-frequency microelectromechanical systems (RFMEMS) and p-i-n diodes, were also studied and directly incorporated onto antenna structures to successfully form frequency-reconfigurable antennas.

Method and system for integrated wireless power and data communication

Abstract: A method and system of integrated wireless power and data transmission in a wireless device having a data communication circuit for wireless data communication and a power reception circuit including a charge storage unit. The wireless device is tuned to receive wireless RF signals in a certain frequency band via an antenna. Switching between power reception mode and data communication mode is detected. Received RF signal electrical charge is selectively distributed to the power reception circuit and/or the data communication circuit based on the switching mode and/or strength of the RF signal.

A review of wearable antenna

Abstract: Utilization of wearable textiles in the antenna segment has been seen on the rise due to the recent miniaturization of wireless devices. A wearable antenna is meant to be a part of the clothing used for communication purposes, which includes tracking and navigation, mobile computing and public safety. This literature review intend to disclose this unconventional antenna technology and provides readers with the background of the wearable antenna that would include about specification of the antenna, material for the antenna and analysis that must be done to design proper wearable antennas. All the designs presented are of the recent development in wearable technology.

Basic Properties and Design Principles of UWB Antennas

Abstract: Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advantages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.

Passive receivers for wireless power transmission

Abstract: Exemplary embodiments are directed to wireless power transfer. A wireless power transmission receiver includes a receive antenna including a parallel resonator configured to resonate in response to a magnetic near-field and couple wireless power therefrom. The receiver further includes a passive rectifier circuit coupled to the parallel resonator. The passive rectifier circuit is configured to transform a load impedance to the parallel resonator.