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Showing papers on "Antenna (radio) published in 2014"


Journal ArticleDOI
TL;DR: It is proved that the huge degrees of freedom offered by massive MIMO can be used to reduce the transmit power and/or to tolerate larger hardware impairments, which allows for the use of inexpensive and energy-efficient antenna elements.
Abstract: The use of large-scale antenna arrays can bring substantial improvements in energy and/or spectral efficiency to wireless systems due to the greatly improved spatial resolution and array gain. Recent works in the field of massive multiple-input multiple-output (MIMO) show that the user channels decorrelate when the number of antennas at the base stations (BSs) increases, thus strong signal gains are achievable with little interuser interference. Since these results rely on asymptotics, it is important to investigate whether the conventional system models are reasonable in this asymptotic regime. This paper considers a new system model that incorporates general transceiver hardware impairments at both the BSs (equipped with large antenna arrays) and the single-antenna user equipments (UEs). As opposed to the conventional case of ideal hardware, we show that hardware impairments create finite ceilings on the channel estimation accuracy and on the downlink/uplink capacity of each UE. Surprisingly, the capacity is mainly limited by the hardware at the UE, while the impact of impairments in the large-scale arrays vanishes asymptotically and interuser interference (in particular, pilot contamination) becomes negligible. Furthermore, we prove that the huge degrees of freedom offered by massive MIMO can be used to reduce the transmit power and/or to tolerate larger hardware impairments, which allows for the use of inexpensive and energy-efficient antenna elements.

841 citations


Journal ArticleDOI
TL;DR: The challenges, benefits and approaches associated with realizing largescale antenna arrays at mmWave frequency bands for future 5G cellular devices are discussed, and a first-of- a-kind cellular phone prototype equipped with mmWave 5G antenna arrays consisting of a total of 32 low-profile antenna elements are developed.
Abstract: This article discusses the challenges, benefits and approaches associated with realizing largescale antenna arrays at mmWave frequency bands for future 5G cellular devices. Key design considerations are investigated to deduce a novel and practical phased array antenna solution operating at 28 GHz with near spherical coverage. The approach is further evolved into a first-of- a-kind cellular phone prototype equipped with mmWave 5G antenna arrays consisting of a total of 32 low-profile antenna elements. Indoor measurements are carried out using the presented prototype to characterize the proposed mmWave antenna system using 16-QAM modulated signals with 27.925 GHz carrier frequency. The biological implications due to the absorbed electromagnetic waves when using mmWave cellular devices are studied and compared in detail with those of 3/4G cellular devices.

509 citations


Journal ArticleDOI
TL;DR: In this article, the authors considered a multi-user decode-and-forward relay channel, where multiple sources transmit simultaneously their signals to multiple destinations with the help of a full-duplex relay station and derived an exact achievable rate expression in closed-form for MRC/MRT processing and an analytical approximation of the achievable rate for ZF processing.
Abstract: We consider a multipair decode-and-forward relay channel, where multiple sources transmit simultaneously their signals to multiple destinations with the help of a full-duplex relay station. We assume that the relay station is equipped with massive arrays, while all sources and destinations have a single antenna. The relay station uses channel estimates obtained from received pilots and zero-forcing (ZF) or maximum-ratio combining/maximum-ratio transmission (MRC/MRT) to process the signals. To significantly reduce the loop interference effect, we propose two techniques: i) using a massive receive antenna array; or ii) using a massive transmit antenna array together with very low transmit power at the relay station. We derive an exact achievable rate expression in closed-form for MRC/MRT processing and an analytical approximation of the achievable rate for ZF processing. This approximation is very tight, particularly for a large number of relay station antennas. These closed-form expressions enable us to determine the regions where the full-duplex mode outperforms the half-duplex mode, as well as to design an optimal power allocation scheme. This optimal power allocation scheme aims to maximize the energy efficiency for a given sum spectral efficiency and under peak power constraints at the relay station and sources. Numerical results verify the effectiveness of the optimal power allocation scheme. Furthermore, we show that, by doubling the number of transmit/receive antennas at the relay station, the transmit power of each source and of the relay station can be reduced by 1.5 dB if the pilot power is equal to the signal power, and by 3 dB if the pilot power is kept fixed, while maintaining a given quality of service.

415 citations


Journal ArticleDOI
TL;DR: It is proved that constellations can be aligned in a similar fashion as that of vectors in multiple antenna systems and space can be broken up into fractional dimensions.
Abstract: In this paper, we develop the machinery of real interference alignment. This machinery is extremely powerful in achieving the sum degrees of freedom (DoF) of single antenna systems. The scheme of real interference alignment is based on designing single-layer and multilayer constellations used for modulating information messages at the transmitters. We show that constellations can be aligned in a similar fashion as that of vectors in multiple antenna systems and space can be broken up into fractional dimensions. The performance analysis of the signaling scheme makes use of a recent result in the field of Diophantine approximation, which states that the convergence part of the Khintchine-Groshev theorem holds for points on nondegenerate manifolds. Using real interference alignment, we obtain the sum DoF of two model channels, namely the Gaussian interference channel (IC) and the X channel. It is proved that the sum DoF of the K-user IC is (K/2) for almost all channel parameters. We also prove that the sum DoF of the X-channel with K transmitters and M receivers is (K M/K + M - 1) for almost all channel parameters.

415 citations


Patent
08 Aug 2014
TL;DR: In this paper, an antenna apparatus for use in harvesting ambient radio frequency, RF, energy is presented, which comprises one or more RF antenna components arranged to receive RF energy for producing electricity.
Abstract: Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.

372 citations


Patent
20 Feb 2014
TL;DR: In this article, surface scattering antennas provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure, and the scattering elements are made adjustable by disposing an electrically adjustable material, such as a liquid crystal, in proximity to the scattering element.
Abstract: Surface scattering antennas provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure. In some approaches, the scattering elements are patch elements. In some approaches, the scattering elements are made adjustable by disposing an electrically adjustable material, such as a liquid crystal, in proximity to the scattering elements. Methods and systems provide control and adjustment of surface scattering antennas for various applications.

315 citations


Journal ArticleDOI
TL;DR: In this paper, a conformal wearable antenna that operates in the 2.36-2.4 GHz medical body-area network band is proposed, which is enabled by placing a highly truncated metasurface, consisting of only a two by two array of I-shaped elements, underneath a planar monopole.
Abstract: We propose a compact conformal wearable antenna that operates in the 2.36-2.4 GHz medical body-area network band. The antenna is enabled by placing a highly truncated metasurface, consisting of only a two by two array of I-shaped elements, underneath a planar monopole. In contrast to previously reported artificial magnetic conducting ground plane backed antenna designs, here the metasurface acts not only as a ground plane for isolation, but also as the main radiator. An antenna prototype was fabricated and tested, showing a strong agreement between simulation and measurement. Comparing to previously proposed wearable antennas, the demonstrated antenna has a compact form factor of 0.5 λ 0 ×0.3 λ 0 ×0.028 λ 0 , all while achieving a 5.5% impedance bandwidth, a gain of 6.2 dBi, and a front-to-back ratio higher than 23 dB. Further numerical and experimental investigations reveal that the performance of the antenna is extraordinarily robust to both structural deformation and human body loading, far superior to both planar monopoles and microstrip patch antennas. Additionally, the introduced metal backed metasurface enables a 95.3% reduction in the specific absorption rate, making such an antenna a prime candidate for incorporation into various wearable devices.

301 citations


Journal ArticleDOI
TL;DR: In this paper, a design method for the co-design and integration of a CMOS rectifier and small loop antenna and a complementary MOS diode is proposed to improve the harvester's ability to store and hold energy over a long period of time during which there is insufficient power for rectification.
Abstract: In this paper, a design method for the co-design and integration of a CMOS rectifier and small loop antenna is described. In order to improve the sensitivity, the antenna-rectifier interface is analyzed as it plays a crucial role in the co-design optimization. Subsequently, a 5-stage cross-connected differential rectifier with a 7-bit binary-weighted capacitor bank is designed and fabricated in standard 90 nm CMOS technology. The rectifier is brought at resonance with a high-Q loop antenna by means of a control loop that compensates for any variation at the antenna-rectifier interface and passively boosts the antenna voltage to enhance the sensitivity. A complementary MOS diode is proposed to improve the harvester's ability to store and hold energy over a long period of time during which there is insufficient power for rectification. The chip is ESD protected and integrated on a compact loop antenna. Measurements in an anechoic chamber at 868 MHz demonstrate a -27 dBm sensitivity for 1 V output across a capacitive load and 27 meter range for a 1.78 W RF source in an office corridor. The end-to-end power conversion efficiency equals 40% at -17 dBm.

289 citations


Journal ArticleDOI
TL;DR: In this article, a compact multiple-input-multiple-output (MIMO) antenna for ultrawideband (UWB) applications is presented, which consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane.
Abstract: A compact multiple-input-multiple-output (MIMO) antenna is presented for ultrawideband (UWB) applications. The antenna consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane. The antenna elements are placed perpendicularly to each other to obtain high isolation, and the narrow slot is added to reduce the mutual coupling of antenna elements in the low frequency band (3-4.5 GHz). The proposed MIMO antenna has a compact size of 32 ×32 mm 2 , and the antenna prototype is fabricated and measured. The measured results show that the proposed antenna design achieves an impedance bandwidth of larger than 3.1-10.6 GHz, low mutual coupling of less than 15 dB, and a low envelope correlation coefficient of better than 0.02 across the frequency band, which are suitable for portable UWB applications.

280 citations


Patent
16 Apr 2014
TL;DR: In this article, one or more tapered feeds can be provided as part of or interconnected to a conductive top plate, and an aperture over the lens region can be covered or filled by an impedance surface.
Abstract: Conformal antennas and methods for radiating radio frequency energy using conformal antennas are provided. In particular, one or more tapered feeds can be provided as part of or interconnected to a conductive top plate. The one or more tapered feeds have a depth that decreases from a feed point to a tip. The tip of the one or more tapered feeds is adjacent a cavity formed over a lens region. An aperture over the lens region can be covered or filled by an impedance surface. This impedance surface may comprise a frequency selective surface. Alternatively, a frequency selective surface can be provided over the lens region of an antenna incorporating one or more stripline feeds.

276 citations


Journal ArticleDOI
TL;DR: A class of microstrip patch antennas that are stretchable, mechanically tunable, and reversibly deformable and well suited for applications like wireless strain sensing are demonstrated.
Abstract: We demonstrate a class of microstrip patch antennas that are stretchable, mechanically tunable, and reversibly deformable. The radiating element of the antenna consists of highly conductive and stretchable material with screen-printed silver nanowires embedded in the surface layer of an elastomeric substrate. A 3-GHz microstrip patch antenna and a 6-GHz 2-element patch array are fabricated. Radiating properties of the antennas are characterized under tensile strain and agree well with the simulation results. The antenna is reconfigurable because the resonant frequency is a function of the applied tensile strain. The antenna is thus well suited for applications like wireless strain sensing. The material and fabrication technique reported here could be extended to achieve other types of stretchable antennas with more complex patterns and multilayer structures.

Journal ArticleDOI
TL;DR: In this paper, an analytical study of the transmission coefficient of multiple conductor layers separated by dielectric materials has been carried out, and the maximum transmission phase range has been determined according to the number of layers, substrate permittivity, and separation between conductor layers.
Abstract: Many transmitarray antennas are designed with multilayer frequency-selective surface (M-FSS) type elements. The goal of this paper is to reveal the transmission phase limit of M-FSS for transmitarray antenna designs. An analytical study of the transmission coefficient of multiple conductor layers separated by dielectric materials has been carried out, and the maximum transmission phase range has been determined according to the number of layers, substrate permittivity, and separation between conductor layers. It is revealed that the -1-dB transmission phase limits are 54°, 170°, 308°, and full 360 °for single-, double-, triple-, and quad-layer FSS consisting of identical layers, respectively. Furthermore, it is shown that if -3-dB criteria is used, a triple-layer FSS is sufficient to achieve the full 360 ° phase range. The effectiveness of the analytical study has been validated through numerical simulations of several representative FSS examples.

Journal ArticleDOI
TL;DR: In this paper, a low-loss and low-cost solution for high gain terahertz (THz) antennas is proposed, where variable height dielectric elements are used in the reflectarray designs.
Abstract: Dielectric reflectarray antennas are proposed as a promising low-loss and low-cost solution for high gain terahertz (THz) antennas. Variable height dielectric elements are used in the reflectarray designs, which allow for the use of low dielectric-constant materials. Polymer-jetting 3-D printing technology is utilized to fabricate the antenna, which makes it possible to achieve rapid prototyping at a low-cost. Numerical and experimental results are presented for 3 different prototypes operating at 100 GHz, which show a good performance. Moreover the methodology proposed here is readily scalable, and with the current material and fabrication technology, designs up to 1.0 THz can be realized. This study reveals that the proposed design approach is well suited for low-cost high-gain THz antennas.

Journal ArticleDOI
TL;DR: In this paper, a sinusoidally modulated graphene leaky-wave antenna with beam scanning capabilities at a fixed frequency is proposed, which is composed of a graphene sheet transferred onto a back-metallized substrate and a set of polysilicon DC gating pads located beneath it.
Abstract: This paper proposes the concept, analysis and design of a sinusoidally modulated graphene leaky-wave antenna with beam scanning capabilities at a fixed frequency. The antenna operates at terahertz frequencies and is composed of a graphene sheet transferred onto a back-metallized substrate and a set of polysilicon DC gating pads located beneath it. In order to create a leaky-mode, the graphene surface reactance is sinusoidally modulated via graphene's field effect by applying adequate DC bias voltages to the different gating pads. The pointing angle and leakage rate can be dynamically controlled by adjusting the applied voltages, providing versatile beamscanning capabilities. The proposed concept and achieved performance, computed using realistic material parameters, are extremely promising for beamscanning at THz frequencies, and could pave the way to graphene-based reconfigurable transceivers and sensors.

Patent
Andrei Panioukov1, Pablo Herrero1
19 Dec 2014
TL;DR: An apparatus for providing a control signal for a variable impedance matching circuit comprises a control module configured to generate a controller for adjusting an impedance of a VEM coupled to an antenna module as mentioned in this paper.
Abstract: An apparatus for providing a control signal for a variable impedance matching circuit comprises a control module configured to generate a control signal for adjusting an impedance of a variable impedance matching circuit coupled to an antenna module. The control module is configured to generate the control signal based on a sensor signal received from a sensor circuit located in proximity to the antenna module. The sensor signal comprises information related to a power of an electromagnetic signal radiated by the antenna module.

Journal ArticleDOI
TL;DR: Two design ideas are proposed, which provide attractive analog/RF-isolation and allow integration in compact radios and combines a dual-port polarized antenna with a self-tunable cancellation circuit.
Abstract: In-band full-duplex sets challenging requirements for wireless communication radios, in particular their capability to prevent receiver sensitivity degradation due to self-interference (transmit signals leaking into its own receiver). Previously published self-interference rejection designs require bulky components and/or antenna structures. This paper addresses this form-factor issue. First, compact radio transceiver feasibility bottlenecks are identified analytically, and tradeoff equations in function of link budget parameters are presented. These derivations indicate that the main bottlenecks can be resolved by increasing the isolation in analog/RF. Therefore, two design ideas are proposed, which provide attractive analog/RF-isolation and allow integration in compact radios. The first design proposal targets compact radio devices, such as small-cell base stations and tablet computers, and combines a dual-port polarized antenna with a self-tunable cancellation circuit. The second design proposal targets even more compact radio devices such as smartphones and sensor network nodes. This design builds on a tunable electrical balance isolator/duplexer in combination with a single-port miniature antenna. The electrical balance circuit can be implemented for scaled CMOS technology, facilitating low cost and dense integration.

Journal ArticleDOI
TL;DR: In this paper, a circular phased array antenna that can generate orbital angular momentum (OAM) radio beams in the 10 GHz band is described, which consists of eight inset-fed patch elements and a microstrip corporate feeding network.
Abstract: A circular phased array antenna that can generate orbital angular momentum (OAM) radio beams in the 10 GHz band is described. The antenna consists of eight inset-fed patch elements and a microstrip corporate feeding network. A full-wave electromagnetic simulator is used to aid the antenna design and theoretical simulations are confirmed by measurements.

Journal ArticleDOI
Min Liang1, Wei-Ren Ng1, Kihun Chang1, Kokou Gbele1, Michael E. Gehm1, Hao Xin1 
TL;DR: In this article, a low-gain 20 dBi Luneburg lens antenna using a rapid prototyping machine as a proof-of-concept demonstrator was designed, built, and tested.
Abstract: In this work, we designed, built, and tested a low-gain 20 dBi Luneburg Lens antenna using a rapid prototyping machine as a proof of concept demonstrator. The required continuously varying relative permittivity profile was implemented by changing the size of plastic blocks centered on the junctions of a plastic rod space frame. A 12-cm ( 4λ0 at 10 GHz) diameter lens is designed to work at X-band. The effective permittivity of the unit cell is calculated by effective medium theory and simulated by full-wave finite-element simulations. The fabrication is implemented by a polymer jetting rapid prototyping method. In the measurement, the lens antenna is fed by an X-band waveguide. The measured gain of the antenna at X-band is from 17.3 to 20.3 dB. The measured half-power beam width is from 19° to 12.7° while the side lobes are about 25 dB below the main peak. Good agreement between simulation and experimental results is obtained.

Journal ArticleDOI
TL;DR: In this article, a hybrid fractal shape planar monopole antenna covering multiple wireless communication bands is presented for multiple-input-multiple-output (MIMO) implementation for handheld mobile devices.
Abstract: A hybrid fractal shape planar monopole antenna covering multiple wireless communication bands is presented for multiple-input-multiple-output (MIMO) implementation for handheld mobile devices. The proposed structure is the combination of Minkowski island curve and Koch curve fractals. It is placed with edge to edge separation of 0.16λ0 at 1.75 GHz. The T-shape strip is inserted and rectangular slot is etched at top side of ground plane, respectively to improve the impedance matching and isolation between the antennas. A measured impedance matching fractional bandwidths ( S11 ≤ -10 dB) are 14% from 1.65 GHz to 1.9 GHz for the band 1 and 80% from 2.68 GHz to 6.25 GHz for the band 2. Acceptable agreement is obtained between the simulated and measured antenna performance parameters. These characteristics demonstrate that the proposed antenna is an attractive candidate for handheld mobile devices.

Journal ArticleDOI
TL;DR: This paper presents a 210-GHz transceiver with OOK modulation in a 32-nm SOI CMOS process (fT/fmax= 250/320 GHz) and is the first demonstration of a fundamental frequency CMOS transceiver at the 200-GHz frequency range.
Abstract: This paper presents a 210-GHz transceiver with OOK modulation in a 32-nm SOI CMOS process (fT/fmax= 250/320 GHz). The transmitter (TX) employs a 2 × 2 spatial combining array consisting of a double-stacked cross-coupled voltage controlled oscillator (VCO) at 210 GHz with an on-off-keying (OOK) modulator, a power amplifier (PA) driver, a novel balun-based differential power distribution network, four PAs, and an on-chip 2 × 2 dipole antenna array. The noncoherent receiver (RX) utilizes a direct detection architecture consisting of an on-chip antenna, a low-noise amplifier (LNA), and a power detector. The VCO generates measured -13.5-dBm output power, and the PA shows a measured 15-dB gain and 4.6-dBm Psat. The LNA exhibits a measured in-band gain of 18 dB and minimum in-band noise figure (NF) of 11 dB. The TX achieves an EIRP of 5.13 dBm at 10 dB back-off from saturated power. It achieves an estimated EIRP of 15.2 dBm when the PAs are fully driven. This is the first demonstration of a fundamental frequency CMOS transceiver at the 200-GHz frequency range.

Patent
21 May 2014
TL;DR: In this article, the authors describe the system and methods for providing broadband internet access to homes and enterprises using a network of aerial platforms such as drones/UAVs/balloons.
Abstract: The present disclosure describes the system and methods for providing broadband internet access to homes and enterprises using a network of aerial platforms such as drones/UAVs/balloons. The drone communication system is composed of an antenna sub-system, a radio sub-system and a data switching sub-system. Drones form and point beams toward ground terminals in different areas in a space division multiple access scheme. Ground terminals are composed of an antenna sub-system and a radio sub-system. Ground terminals search for the drone from which they receive the strongest signals. Drone and ground terminals comprise of methods and systems to calibrate receive and transmit antenna elements. Drone radio sub-system keeps track of the drone's position and orientation changes and adjust drone's antenna beam accordingly to point to the same location on the ground as the drone moves. Depending on the changes in drone's position and orientation, the drone radio sub-system may switch the antenna aperture and/or the antenna fixture that is used to form a beam toward a specific ground terminal. Drones communicate with the terminals using a space and time division multiple access scheme.

Patent
23 Dec 2014
TL;DR: In this paper, a rectifying circuit that facilitates harvesting multiband RF signals having low energy levels (i.e., tens of mW and below) by utilizing two zero bias Schottky diodes having different forward voltage and peak inverse voltage values is presented.
Abstract: A radio frequency (RF) energy harvesting device (rectenna) includes an antenna structure configured to resonate at RF frequencies, and a rectifying circuit that facilitates harvesting multiband RF signals having low energy levels (i.e., tens of mW and below) by utilizing two Zero Bias Schottky diodes having different forward voltage and peak inverse voltage values. Positive voltage pulses from a captured RF signal generated on a first antenna end point are passed by the first diode to a first internal node where they are summed with a second RF signal generated on the second antenna end point (i.e., after being passed through a capacitor), thereby producing a first intermediate voltage having a substantially higher voltage level. Positive voltage pulses are then passed from the first internal node through the second diode to an output control circuit for conversion into a usable DC output voltage.

Book
01 Apr 2014
TL;DR: Antenna Fundamentals for Legacy Mobile Applications and BeyondPrinted MIMO Antenna EngineeringRecent Technical Developments in Energy-Efficient 5G Mobile Cells
Abstract: Wireless communications has made a huge leap during the past two decades. The multiple-input-multiple-output (MIMO) technology was proposed in the 1990's as a viable solution that can overcome the data rate limit experienced by single-input-single-output (SISO) systems. This resource is focused on printed MIMO antenna system design. Printed antennas are widely used in mobile and handheld terminals due to their conformity with the device, low cost, good integration within the device elements and mechanical parts, as well as ease of fabrication. A perfect design companion for practicing engineers, this book provides full design examples from literature, along with detailed illustrations for the various antenna geometries. This resource overviews the various applications that currently depend on printed MIMO antennas, and provides design guidelines and remarks throughout the book for guidance.

Patent
06 Feb 2014
TL;DR: In this paper, the authors provide a receiver configuration and application for wireless power transmission for smart mobile devices, where the receiver may include a plurality of antenna elements connected to at least one rectifier and one power converter, and the antenna elements may be arranged around the internal edge of any suitable smart mobile device.
Abstract: The present disclosure may provide a receiver configuration and application, which may be used to provide wireless power transmission for smart mobile devices. Specifically, the receiver may include a plurality of antenna elements connected to at least one rectifier and one power converter. Additionally, the antenna elements may be arranged around the internal edge of any suitable smart mobile device, and antenna elements may include an optimal spacing to provide a better reception, efficiency, and performance of wireless power transmission. Moreover, the disclosed receiver may be used as an internal or external hardware in smart mobile devices.

Journal ArticleDOI
TL;DR: In this paper, a dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed.
Abstract: A novel wearable dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed. By using brass eye-lets and a combination of conducting and non-conductive textile materials, a half-mode substrate integrated waveguide cavity with ground plane is realized that is very compact and flexible, while still directing radiation away from the wearer. Additional miniaturization is achieved by adding a row of shorting vias and slots. Beside excellent free space performance in the 2.4 and 5.8 GHz bands, respectively, with measured impedance bandwidth of 4.9% and 5.1%, maximal measured free-space gain of 4.1 and 5.8 dBi, and efficiency of 72.8% and 85.6%, very stable on-body performance is obtained, with minimal frequency detuning when deploying the antenna on the human body and when bent around cylinders with radii of 75 and 40 mm. At 2.45 and 5.8 GHz, respectively, the measured on-body gain is 4.4 and 5.7 dBi, with sufficiently small calculated SAR values of 0.55 and 0.90 W/kg. These properties make the proposed antenna excellently suited for wearable on-body systems.

Patent
30 Dec 2014
TL;DR: In this article, a plurality of antenna arrangements that may be suitable for wireless power transmission based on single or multiple pocket-forming are described, which may operate as a single array, pair array, quad array or any other suitable arrangement.
Abstract: The present disclosure describes a plurality of antenna arrangements that may be suitable for wireless power transmission based on single or multiple pocket-forming. Single or multiple pocket-forming may include one transmitter and at least one or more receivers, being the transmitter the source of energy and the receiver the device that is desired to charge or power. The antenna arrangements may vary in size and geometry, and may operate as a single array, pair array, quad arrays or any other suitable arrangement, which may be designed in accordance with the desired application.

Patent
17 Jul 2014
TL;DR: In this article, the authors describe a methodology for wireless power transmission based on pocket-forming, which includes a transmitter device capable of forming pockets of energy used by a receiver device to charge an electronic device such as a computers, cell phones, tablet and/or devices of the like.
Abstract: The present disclosure describes a methodology for wireless power transmission based on pocket-forming. The method includes a transmitter device capable of forming pockets of energy used by a receiver device to charge an electronic device such as a computers, cell phones, tablet and/or devices of the like. The method may include using an array of antennas at the transmitter to locate the position of a receiver device. The transmitter may identify the position of the device by capturing a signal from a receiving device using two subsets from the array of antennas. The subset of antennas may then be adjusted to form pockets of energy at the appropriate location of the receiving device. Previously stored data pertaining to each antenna in the array may serve to determine the proper adjustments for the entire array of antennas based on the results from the subsets used to capture the receivers signal.

Journal ArticleDOI
TL;DR: In this article, a multi-antenna design approach was proposed to obtain efficient and uncorrelated antennas at frequency bands below 1 GHz by manipulating the chassis structure, and two antenna feeds were designed to efficiently excite the chassis' fundamental dipole mode and the T-strip mode with very low correlation.
Abstract: Multi-antenna design in compact mobile handsets at frequency bands below 1 GHz is very challenging, since severe mutual coupling is commonly induced by simultaneous excitation of the chassis' fundamental dipole mode by more than one antenna element. To address this problem, a novel multi-antenna design approach is proposed herein to obtain efficient and uncorrelated antennas. By manipulating the chassis structure, more than one characteristic mode is enabled to resonate at frequencies below 1 GHz. With proper excitations for different characteristic modes, which are orthogonal to each other, well matched multi-antennas with low coupling and correlation are achieved. A chassis loaded with two T-shaped metal strips above its longer edges is taken as an example modification to illustrate the effectiveness of the proposed design approach at 900 MHz. This modification creates a new characteristic mode which resonates near 900 MHz. Afterward, two antenna feeds were designed to efficiently excite the chassis' fundamental dipole mode and the T-strip mode with very low correlation. The T-strip antenna covers LTE Band 8 (880-960 MHz), and the dipole mode antenna covers both LTE Band 5 (824-894 MHz) and LTE Band 8. The proposed dual-antenna design was found to outperform a reference design significantly, both with and without user interactions (i.e., one-hand and two-hand data grips). Practical aspects of mobile handset antennas are also investigated. The prototype was also fabricated and measured, and the measured results show reasonable agreements with the simulated results.

Patent
03 Jan 2014
TL;DR: In this paper, an antenna that receives electrical waves and at least two charging power generators that generate charging power for charging a battery using the electrical waves received through the antenna was provided.
Abstract: A wireless charging apparatus is provided The wireless charging apparatus includes: an antenna that receives electrical waves; at least two charging power generators that generate charging power for charging a battery using the electrical waves received through the antenna; and a controller that senses a frequency of the electrical waves received through the antenna and that activates one of the at least two charging power generators according to a sensed result

Journal ArticleDOI
TL;DR: In this paper, the design of a compact split ring resonator (SRR) loaded coplanar waveguide (CPW) fed ultrawideband circular monopole antenna having frequency notch characteristics is presented.
Abstract: This paper presents the design of a compact split ring resonator (SRR) loaded coplanar waveguide (CPW) fed ultrawideband circular monopole antenna having frequency notch characteristics. The electromagnetic coupling of the SRR with the CPW yields the frequency notch. Fabricated prototypes were measured and compared with simulations and good agreement was obtained. The impedance and radiation plots confirm the suppression of the desired notch frequency. A theoretical formulation to calculate the notch frequency is also proposed and validated.