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Showing papers on "Frequency band published in 2013"


Proceedings ArticleDOI
12 Dec 2013
TL;DR: A basic tutorial on the types of radio frequency communications and the benefits and liabilities of each are given and specific topics to be explored will be licensed verses unlicensed frequencies, distance between remote radios and base stations, and communications architectures.
Abstract: Radio Frequency (RF) communications are an important smart grid enabler for functions such as volt/VAR control, recloser control, and feeder restorations and isolation. This paper will give a basic tutorial on the types of radio frequency communications and the benefits and liabilities of each. Specific topics to be explored will be licensed verses unlicensed frequencies, distance between remote radios and base stations, and communications architectures. Radio technology is often referred in numerical ranges or frequencies. The decision on which frequency to employ in a network depends on a few key variables. Prior to deciding which frequency for a network, the application for the radio use will assist with dictation of which frequency range to utilize. Applications such as recloser control and volt/Var control may require a radio device that can provide a high bandwidth/fast speed solution. Other SCADA applications such as sensor monitoring may only require small bandwidth and for data delivery to be at a much slower speed. Another variable when deciding on a radio network is the distance from the main SCADA hosts to end remote devices such as RTUs or PLCs. Lower end frequencies (100 MHz-900 MHz) provide further coverage and greater distance from base stations/Access Points to remote end devices, whereas higher frequencies (2.4 GHz-5.8 GHz) provide shorter distance coverage, but higher bandwidth and relay data back to SCADA hosts much faster. Determining a network's architecture should focus on either the desire of a private, licensed network or the notion of an unlicensed, less expensive network. The lower licensed frequency ranges (100 MHz, 200 MHz, 400 MHz and upper 900 MHz bands) are often referred to as MAS (Multiple Address Systems) networks and require license acquisition from the FCC once geographical coverage is determined. These licenses are granted for the lower frequencies as mentioned previously but are considered the proprietary use of the owner. Anyone operating in these frequencies will be fined/cited by the FCC. The less expensive, unlicensed network is allowable for frequencies ranging from 902 MHz-928 MHz, which is defined as the ISM (Industrial, Scientific, and Medical) bands. Within the unlicensed frequency band, there exist registered bands (3.65 GHz) that employ WiMax (Wireless Microwave Access for Broadband) technology that provide shorter coverage for remote devices, however, the bandwidth and speed provided by these frequencies make them just as popular for networks. Further analysis and discussion of licensed versus unlicensed radio wireless communications is proposed in this paper.

492 citations


Journal ArticleDOI
TL;DR: In this article, a single-layer circuit analog absorber using double-square-loop array reveals that three resonances can be obtained within its operating frequency band, and an equivalent circuit model is proposed to explain how these three resonance can be produced and its absorption bandwidth can be widened.
Abstract: A detailed study of a single-layer circuit analog absorber using double-square-loop array reveals that three resonances can be obtained within its operating frequency band. An equivalent circuit model is proposed to explain how these three resonances can be produced and its absorption bandwidth can be widened. Simple guidelines for the design of this double-square-loop absorber are then formulated. It is shown through measurements that the fractional bandwidth of 126.8% is realized for at least 10 dB reflectivity reduction under the normal incidence. Furthermore, the total thickness of the proposed design is only 0.088λL at the lowest operating frequency. A good agreement between simulated and measured results demonstrates the validity of our design.

347 citations


Journal ArticleDOI
Jie Zhao1, Qiang Cheng, Chen Jie1, Mei Qing Qi1, Wei Xiang Jiang1, Tie Jun Cui 
TL;DR: In this article, a polarization-insensitive tunable tunable metamaterial absorber with varactor diodes embedded between metammaterial units is presented. But the design, analysis and measurements of the tunability of the absorber are not discussed.
Abstract: We present the design, analysis and measurements of a polarization-insensitive tunable metamaterial absorber with varactor diodes embedded between metamaterial units. The basic unit shows excellent absorptivity in the designed frequency band over a wide range of incident angles. By regulating the reverse bias voltage on the varactor diode, the absorption frequency of the designed unit can be controlled continuously. The absorption mechanism is interpreted using the electromagnetic-wave interference theory. When the metamaterial units are placed along two orthogonal directions, the absorber is insensitive to the polarization of incident waves. The tunability of the absorber has been verified by experimental results with the measured bandwidth of 1.5?GHz (or relative bandwidth of 30%).

290 citations


Proceedings ArticleDOI
07 Apr 2013
TL;DR: The system performance analysis of 3GPP Long-Term Evolution (LTE) and IEEE 802.11 Wireless Local Area Networks (WLAN) in a situation where LTE downlink has been expanded over to unlicensed frequency band usually used by WLAN is presented.
Abstract: This paper presents the system performance analysis of 3GPP Long-Term Evolution (LTE) and IEEE 802.11 Wireless Local Area Networks (WLAN) in a situation where LTE downlink (DL) has been expanded over to unlicensed frequency band usually used by WLAN. Simple fractional bandwidth sharing mechanism is used to allow both technologies to transmit. The system performance is evaluated by means of fully dynamic network simulations.

188 citations


Journal ArticleDOI
TL;DR: In this paper, a low-profile, ultrawideband, true-time-delay (TTD) equivalent microwave lenses are designed, fabricated, and experimentally characterized at X-band.
Abstract: We present a new technique for designing low-profile, ultrawideband, true-time-delay (TTD) equivalent microwave lenses. Such a lens is composed of numerous spatial time-delay units (TDUs) distributed over a planar surface. Each spatial TDU is the unit cell of an appropriately designed miniaturized-element frequency selective surface and provides a frequency-independent time delay within the frequency band of interest. Two TTD lens prototypes with focal length to aperture dimension (f/D) ratios of 1 and 1.6 are designed, fabricated, and experimentally characterized at X-band. The 3-dB gain bandwidths of these lenses are respectively 7.5-11.6 and 7.8-11.5 GHz. Each fabricated lens has an overall thickness of 4.76 mm, which corresponds to ~ 0.150λ0, where λ0 is the free-space wavelength at the center frequency of operation. Each lens uses spatial TDUs with physical dimensions of 6 × 6 mm2, or ~ 0.19λ0 × 0.19λ0. Both lenses have a system fidelity factor close to 1, when excited with a broadband pulse. Furthermore, due to their true-time-delay equivalent behavior, the fabricated lenses do not suffer from chromatic aberration within their operational bands. When used in a beam-scanning antenna system, each lens demonstrates an excellent scanning performance in a field of view of ± 60°.

175 citations


Journal ArticleDOI
TL;DR: An active impedance metasurface with full 360° reflection phase control is presented to remove the phase tuning deficiency in conventional approach and can be applied to many cases where fine and full phase tuning is needed, such as beam steering in reflectarray antennas.
Abstract: Impedance metasurface is composed of electrical small scatters in two dimensional plane, of which the surface impedance can be designed to produce desired reflection phase. Tunable reflection phase can be achieved by incorporating active element into the scatters, but the tuning range of the reflection phase is limited. In this paper, an active impedance metasurface with full 360° reflection phase control is presented to remove the phase tuning deficiency in conventional approach. The unit cell of the metasurface is a multiple resonance structure with two resonance poles and one resonance zero, capable of providing 360° reflection phase variation and active tuning within a finite frequency band. Linear reflection phase tuning can also be obtained. Theoretical analysis and simulation are presented and validated by experiment at microwave frequency. The proposed approach can be applied to many cases where fine and full phase tuning is needed, such as beam steering in reflectarray antennas.

170 citations


Journal ArticleDOI
TL;DR: The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102 by adjusting the cavity magnetic field.
Abstract: Experimental results are presented of the first successful gyrotron backward wave oscillator (gyro-BWO) with continuous frequency tuning near the low-terahertz region. A helically corrugated interaction region was used to allow efficient interaction over a wide frequency band at the second harmonic of the electron cyclotron frequency without parasitic output. The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field. The performance of the gyro-BWO is consistent with 3D particle-in-cell numerical simulations.

148 citations


Journal ArticleDOI
TL;DR: In this article, the dynamics and power flow behavior of a nonlinear vibration isolation system with a negative stiffness mechanism (NSM) was studied. But the authors did not consider the effect of sub-harmonic resonance on the power flow of the system.

143 citations


Journal ArticleDOI
Weiqun Liu1, Adrien Badel1, Fabien Formosa1, Yipeng Wu1, Amen Agbossou1 
TL;DR: In this paper, a buckled spring-mass architecture is proposed to convert the energy of the dynamic mass to electrical energy in the piezoelectric materials as efficiently as possible.
Abstract: Bistable vibration energy harvesters are attracting more and more interest because of their capability to scavenge energy over a large frequency band. The bistable effect is usually based on magnetic interaction or buckled beams. This paper presents a novel architecture based on amplified piezoelectric structures. This buckled spring‐mass architecture allows the energy of the dynamic mass to be converted into electrical energy in the piezoelectric materials as efficiently as possible. Modeling and design are performed and a normalized expression of the harvester behavior is given. Chirp and band-limited noise excitations are used to evaluate the proposed harvester’s performances. Simulation and experimental results are in good agreement. A method of using a spectrum plot for investigating the interwell motion is presented. The effect of the electric load impedance matching strategy is also studied. Results and comparisons with the literature show that the proposed device combines a large bandwidth and a high power density. (Some figures may appear in colour only in the online journal)

141 citations


Journal ArticleDOI
TL;DR: This study demonstrates that coherent delta-band oscillations reflect the linkage between distant parietal and frontal cortical circuits during decision making, and indicates an important role for synchronous activity in the delta frequency band when large-scale, distant cortical networks coordinate their neural activity during decisionMaking.
Abstract: Coherent oscillations in the theta-to-gamma frequency range have been proposed as a mechanism that coordinates neural activity in large-scale cortical networks in sensory, motor, and cognitive tasks. Whether this mechanism also involves coherent oscillations at delta frequencies (1–4 Hz) is not known. Rather, delta oscillations have been associated with slow-wave sleep. Here, we show coherent oscillations in the delta frequency band between parietal and frontal cortices during the decision-making component of a somatosensory discrimination task. Importantly, the magnitude of this delta-band coherence is modulated by the different decision alternatives. Furthermore, during control conditions not requiring decision making, delta-band coherences are typically much reduced. Our work indicates an important role for synchronous activity in the delta frequency band when large-scale, distant cortical networks coordinate their neural activity during decision making.

130 citations


Patent
15 Aug 2013
TL;DR: In this article, a dual-band feed horn with a connection surface configured for connection to a waveguide and a first surface coupled to the connection surface is presented, which has a bandwidth ratio of the high-frequency band to the low frequency band in the range of 1.6-4.0.
Abstract: A dual-band feed horn having a connection surface configured for connection to a waveguide and a first surface coupled to the connection surface. The first surface has a cylindrical surface with a length and a first diameter chosen to propagate TE11 modes for both a low frequency band and a high frequency band. The horn has a bandwidth ratio of the high-frequency band to the low frequency band in the range of 1.6-4.0. The horn also has a substantially conical surface coupled to the first surface at a first slope discontinuity. The conical surface includes multiple surfaces each having a respective slope and coupled to adjacent surfaces by a respective plurality of slope discontinuities each having a respective diameter. The slopes and diameters are chosen to generate primarily TM1,m modes (m=1, 2, 3, etc.) in the high-frequency band and primarily higher order TE1,n modes (n=2, 3, etc.) in the low-frequency band such that the low frequency band and the high frequency band have approximately equal beam widths.

Journal ArticleDOI
TL;DR: In this article, a printed reconfigurable ultra-wideband (UWB) monopole antenna with triple narrow band-notched characteristics is proposed for cognitive radio applications, which can work at eight modes by controlling switches ON and OFF.
Abstract: A printed reconfigurable ultra-wideband (UWB) monopole antenna with triple narrow band-notched characteristics is proposed for cognitive radio applications in this paper. The triple narrow band-notched frequencies are obtained using a defected microstrip structure (DMS) band stop filter (BSF) embedded in the microstrip feed line and an inverted π-shaped slot etched in the rectangular radiation patch, respectively. Reconfigurable characteristics of the proposed cognitive radio antenna (CRA) are achieved by means of four ideal switches integrated on the DMS-BSF and the inverted π-shaped slot. The proposed UWB CRA can work at eight modes by controlling switches ON and OFF. Moreover, impedance bandwidth, design procedures, and radiation patterns are presented for analysis and explanation of this antenna. The designed antenna operates over the frequency band between 3.1 GHz and 14 GHz (bandwidth of 127.5%), with three notched bands from 4.2 GHz to 6.2 GHz (38.5%), 6.6 GHz to 7.0 GHz (6%), and 12.2 GHz to 14 GHz (13.7%). The antenna is successfully simulated, fabricated, and measured. The results show that it has wide impedance bandwidth, multimodes characteristics, stable gain, and omnidirectional radiation patterns.

Journal ArticleDOI
TL;DR: This work presents the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime, and finds a broad transparency window across a frequency range greater than 0.40 THz is obtained.
Abstract: Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range. (Some figures may appear in colour only in the online journal)

Journal ArticleDOI
TL;DR: In this paper, a new framework is proposed to further exploit TCM to enhance the performance of the orthogonal MIMO antennas by correlating the characteristic currents and near fields of modes with high modal significance in a given frequency band.
Abstract: Recent work has shown that, with the help of the Theory of Characteristic Modes (TCM), minor modifications of the terminal chassis can facilitate the design of orthogonal multiple-input-multiple-output (MIMO) antennas with viable bandwidth at frequencies below 1 GHz. Herein, a new framework is proposed to further exploit TCM to enhance the performance of the orthogonal MIMO antennas. By correlating the characteristic currents and near fields of modes with high modal significance in a given frequency band, a single feed may be designed to excite multiple modes, leading to enlarged bandwidth. Similarly, the correlation of characteristic currents and near fields across different bands provides candidate modes that can be excited for multiband operation using a single feed. Moreover, the impedance matching of these modes can be improved by additional structural manipulation. As proof of concept, a dual-band (818-896 MHz, 1841-2067 MHz), dual-antenna prototype was designed on a 130 × 66-mm2 chassis for Long Term Evolution (LTE) operation. Full-wave simulation results were experimentally verified with a fabricated prototype.

Journal ArticleDOI
TL;DR: In this article, two different frequency-adaptive approaches for class-P and -M compliance to ensure operation over a wide frequency range were considered. And the authors concluded that a class-M PMU is unsatisfactory for wide-area stabilizing control, unless its performance is improved during the fault period.
Abstract: For the first time, IEEE Std. C37.118.1-2011 now provides metrics for PMU dynamic performance in terms of classes P and M filter designs. This paper attempts to determine whether fulfilling these requirements makes the PMU inherently well suited for stability control applications such as wide-area power system stabilizers (PSSs). In this aim, we considered two different frequency-adaptive approaches for class-P and -M compliance to ensure operation over a wide frequency range. The first is based on a finite-impulse response (FIR) with no overshoot in either the phase or the amplitude step responses, while the second is Kalman filter-based (EKF), which allows for a more refined out-of-band interference rejection at the cost of a phase step response with overshoot. These two approaches are benchmarked against Hydro-Quebec`s existing PSS requirements and the conclusion is that the total vector error-based response time is not indicative of the phase lag within the frequency band of interest, nor of the 3-dB bandwidth under sinusoidal amplitude/frequency modulation phenomena, which are key criteria when specifying PSS PMUs. Using simulated and field-recorded network fault responses, we also show that a class-M PMU is unsatisfactory for wide-area stabilizing control, unless its performance is improved during the fault period, which is not covered by Std. C37.118.1-2011.

Journal ArticleDOI
TL;DR: In this paper, a flat lens made by a conventional material and an epsilon near-zero metamaterial was proposed to plug up the aperture of a short horn antenna, in order to achieve radiation performances similar to the ones of the corresponding optimum horn over a broad frequency range.
Abstract: We present the design of a flat lens, made by a conventional material and an epsilon near-zero metamaterial, to plug up the aperture of a short horn antenna, in order to achieve radiation performances similar to the ones of the corresponding optimum horn over a broad frequency range. Lens operation is based on the phase-compensation concept: phase-fronts of the field propagating along the short flare of the horn propagate with different phase velocities in the two lens materials, resulting in an uniform phase distribution on the aperture. Starting from the theoretical study of the transmission properties of a bulk epsilon near-zero slab, we derive the analytical formulas for the design of the flat lens and validate them through full-wave numerical simulations. Then, a realistic version of the lens, realized with a wire-medium and exhibiting a near-zero real part of the effective permittivity in the frequency range of interest, is presented. Considering two examples working in the C-band, we show that the lens can be designed for both conical and pyramidal horn antennas. In both cases, the length of the horns is half the one of the corresponding optimum versions, while the obtained radiation performances are similar to those of the optimum horns over a broad frequency band. This result may open the door to several interesting applications in satellite and radar systems.

Journal ArticleDOI
Yu Jian Cheng, Hang Xu, Da Ma1, Jie Wu, Lei Wang, Yong Fan 
TL;DR: In this article, a millimeter-wave shaped-beam substrate integrated conformal array antenna is demonstrated in a single dielectric substrate together with an 8 × 8 slot array at the center frequency of 35 GHz.
Abstract: A millimeter-wave shaped-beam substrate integrated conformal array antenna is demonstrated in this paper After discussing the influence of conformal shape on the characteristics of a substrate integrated waveguide (SIW) and a radiating slot, an array mounted on a cylindrical surface with a radius of 20 mm, ie, 23 λ, is synthesized at the center frequency of 35 GHz All components, including a 1-to-8 divider, a phase compensated network and an 8 × 8 slot array are fabricated in a single dielectric substrate together In measurement, it has a - 274 dB sidelobe level (SLL) beam in H-plane and a flat-topped fan beam with -38° ~ 37° 3 dB beamwidth in E-plane at the center frequency of 35 GHz The cross polarization is lower than -417 dB at the beam direction Experimental results agree well with simulations, thus validating our design This SIW scheme is able to solve the difficulty of integration between conformal array elements and a feed network in millimeter-wave frequency band, while avoid radiation leakage and element-to-element parasitic cross-coupling from the feed network

Patent
10 Sep 2013
TL;DR: In this paper, the authors proposed a communication device using a millimeter-wave frequency band and a communication method using the millimeter wave frequency band, which includes a beam scheduling unit configured to schedule uplink and downlink beams corresponding to movement of a terminal, a core network interface unit, and an inter-base station interface unit configuring to exchange a control message with another base station under control of the mobility management unit.
Abstract: There are provided a communication device using a millimeter-wave frequency band and a communication method using the millimeter-wave frequency band. The communication device includes a beam scheduling unit configured to schedule uplink and downlink beams corresponding to movement of a terminal, a core network interface unit configured to transmit data provided from the beam scheduling unit to a core network, and to provide data received from the core network to the beam scheduling unit, a mobility management unit configured to configure an uplink and downlink beam set based on inter-beam interference information provided from the beam scheduling unit, and an inter-base station interface unit configured to exchange a control message with another base station under control of the mobility management unit. Therefore, it is possible to efficiently build a cellular network using the millimeter-wave frequency band.

Patent
11 Jan 2013
TL;DR: In this article, a wireless network may implement a reduced bandwidth for control information transmitted and/or received on the wireless network to avoid interference that may be detected from an in-band or adjacent channel.
Abstract: A wireless network may implement a reduced bandwidth for control information transmitted and/or received on the wireless network. The reduced bandwidth may be used to avoid interference that may be detected from an in-band or adjacent channel. The reduced bandwidth may be used for transmission and/or reception of control information on a cellular or Wi-Fi channel. An eNB or an access point (AP) may signal to a wireless transmit/receive unit (WTRU) information associated with the reduced control channel, such as the power and/or the location of the channel in a frequency band. The control channel may be shifted to avoid a change in interference.

Journal ArticleDOI
TL;DR: In this article, an automatic selection process for finding the optimal complex Morlet wavelet filter with the help of genetic algorithm that maximizes the sparsity measurement value was presented, and the modulus of the wavelet coefficients obtained by the optimal wavelet filtering was used to extract the envelope.

Patent
15 Aug 2013
TL;DR: In this paper, a telecommunication system can include a first section and a second section, where the first section can receive signals from at least one transmitting base station or transmitting terminal device, and the second section can extract signals from the combined frequency band.
Abstract: Telecommunication systems using multiple Nyquist zone operations are provided. In one aspect, a telecommunication system can include a first section and a second section. The first section can receive signals from at least one transmitting base station or transmitting terminal device. The received signals have frequencies in multiple frequency bands. The first section can also sample the received signals such that the received signals are aliased. The first section can also combine the aliased signals from the frequency bands into a combined frequency band in a common Nyquist zone. The second section can extract signals from the combined frequency band. The extracted signals are to be transmitted at frequencies in a frequency band from a Nyquist zone that is different than the common Nyquist zone. The second section can also transmit the extracted signals to at least one receiving base station or receiving terminal device.

Journal ArticleDOI
TL;DR: In this article, a planar dual-band monopole antenna with a frequency-tunable band is presented, where a simple and novel biasing circuit, consisting of two radio frequency (RF) choke resistors and an L-shaped stub, is designed for biasing the varactor.
Abstract: A planar dual-band monopole antenna with a frequency-tunable band is presented. The structure of the antenna radiator has a stem connecting to two branches that are used to generate two frequency bands at around 2.4 and 3.4 GHz for Worldwide Interoperability for Microwave Access (WiMAX) applications. The lower band covers the WiMAX frequency band of 2.3–2.4 GHz, while the higher band is frequency-tunable to the WiMAX frequency bands of 3.3–3.4, 3.4–3.6and 3.6–3.8 GHz. The frequency tunability is achieved by using the reverse-bias voltage across a varactor that is placed between the stem and one of the radiating branches of the radiator. In this study, the radiating branch responsible for the higher band is selected for tuning. A simple and novel biasing circuit, consisting of two radio frequency (RF) choke resistors and an L-shaped stub, is designed for biasing the varactor. Results show that the higher band can be continuously tuned in frequency, yet keeping the lower band unchanged. The reflection coefficient, radiation pattern, and efficiency of the antenna are studied using computer simulation and measurement.

Journal ArticleDOI
TL;DR: In this article, a 2 x 5 EBG lattice is inserted between the E-plane coupled array which reduced the coupling level by 17 dB without any adverse effect on the radiation performances.
Abstract: The periodic structure like electromagnetic band gap (EBG) is a hot research topic in the academia and RF-microwave industry due to their extraordinary surface wave suppression property. This study involved in designing a compact uni-planar type EBG structure for a 2.4 GHz resonant frequency band. Double folded bend metallic connecting lines are successfully utilized to realize a low frequency structure while a size reduction of 61% is achieved compared to the theoretically calculated size. From the transmission response, the surface wave band gap (SWBG) is found to be 1.2 GHz (1.91-3.11 GHz) whereas the artificial magnetic conductor (AMC) characteristic is observed at 3.3 GHz. The FEM based EM simulator HFSS is used to characterize the EBG structure. The SWBG property is utilized for alleviation of mutual coupling between elements of a microstrip antenna array. A 2 x 5 EBG lattice is inserted between the E-plane coupled array which reduced the coupling level by 17 dB without any adverse effect on the radiation performances.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that large transmission loss can be achieved across a sizable orifice through which air can freely flow and find that interaction of resonating field of acoustic metamaterials with the continuous sound field passing through the orifice is responsible for such phenomenon.
Abstract: Conventional means of attenuating airborne sound usually require blocking the air medium with a solid material By exploiting properties of membrane-type acoustic metamaterials (MAMs), we demonstrate large transmission loss to be achievable across a sizable orifice through which air can freely flow We find that interaction of resonating field of the MAMs with the continuous sound field passing through the orifice is responsible for such phenomenon The narrow-band characteristic of this effect can be used for acoustic filtering of noise with a particular narrow frequency band

Journal ArticleDOI
TL;DR: A design procedure for D-band CMOS circuits is overviewed from the device layer to the system layer, where the architecture is optimized to realize both low power and high data transfer rate.
Abstract: Recently, short-distance high-speed wireless communication using a 60 GHz band has been studied for mobile application. To realize higher-speed wireless communication while maintaining low power consumption for mobile application D band (110-170 GHz) is promising since it can potentially provide a wider frequency band. Thus, we have studied D-band CMOS circuits to realize low-power ultrahigh-speed wireless communication. In the D band, however, since no sufficient device model is provided, research generally has to start from device modeling. In this paper, a design procedure for D-band CMOS circuits is overviewed from the device layer to the system layer, where the architecture is optimized to realize both low power and high data transfer rate. Finally, a 10 Gbps wireless transceiver with a power consumption of 98 mW is demonstrated using the 135 GHz band.

Journal ArticleDOI
TL;DR: In this article, the authors examined the potential sensitivity of three ground-based detector concepts aimed at radiation in the 0.1-10 Hz band and made estimates for their event rates and thereby, the sensitivity requirements for these detectors.
Abstract: Direct detection of gravitational radiation in the audio band is being pursued with a network of kilometer-scale interferometers (LIGO, Virgo, KAGRA). Several space missions (LISA, DECIGO, BBO) have been proposed to search for sub-hertz radiation from massive astrophysical sources. Here we examine the potential sensitivity of three ground-based detector concepts aimed at radiation in the 0.1--10 Hz band. We describe the plethora of potential astrophysical sources in this band and make estimates for their event rates and thereby, the sensitivity requirements for these detectors. The scientific payoff from measuring astrophysical gravitational waves in this frequency band is great. Although we find no fundamental limits to the detector sensitivity in this band, the remaining technical limits will be extremely challenging to overcome.

Journal ArticleDOI
TL;DR: This study examines a soft tissue mimicking phantom material (Ecoflex) over a wide frequency range (200 Hz to 7.75 kHz) and highlights the advantages of measuring the complex‐valued shear modulus over as wide a range of frequencies as possible.
Abstract: The growing clinical use of MR Elastography (MRE) requires the development of new quantitative standards for measuring tissue stiffness. Here, we examine a soft tissue mimicking phantom material (Ecoflex) over a wide frequency range (200 Hz to 7.75 kHz). The recorded data are fit to a cohort of viscoelastic models of varying complexity (integer and fractional order). This was accomplished using multiple sample sizes by employing geometric focusing of the shear wave front to compensate for the changes in wavelength and attenuation over this broad range of frequencies. The simple axisymmetric geometry and shear wave front of this experiment allows us to calculate the frequency-dependent complex-valued shear modulus of the material. The data were fit to several common models of linear viscoelasticity, including those with fractional derivative operators, and we identified the best possible matches over both a limited frequency band (often used in clinical studies) and over the entire frequency span considered. In addition to demonstrating the superior capability of the fractional order viscoelastic models, this study highlights the advantages of measuring the complex-valued shear modulus over as wide a range of frequencies as possible.

Journal ArticleDOI
TL;DR: In this article, the authors investigate the sound propagation in an air-filled tube periodically loaded with Helmholtz resonators and study the efficiency of slow sound propagation under the presence of the intrinsic viscothermal losses of the system.
Abstract: We investigate the sound propagation in an air-filled tube periodically loaded with Helmholtz resonators. By tuning the Helmholtz with the Bragg resonance, we study the efficiency of slow sound propagation in the presence of the intrinsic viscothermal losses of the system. While in the lossless case the overlapping of the resonances results in slow sound induced transparency of a narrow frequency band surrounded by a strong and broadband gap, the inclusion of the unavoidable losses imposes limits to the slowdown factor and the maximum transmission. Experiments, theory and finite element simulations have been used for the characterization of acoustic wave propagation. Experiments, in good agreement with the lossy theory, reveal the possibility of slowing sound at low frequencies by 20 times. A trade-off among the relevant parameters (delay time, maximum transmission, bandwidth) as a function of the tuning between Bragg and Helmholtz resonance frequency is also presented.

Journal ArticleDOI
TL;DR: In this paper, a compact ultra-wideband microstrip-fed annular ring antenna with band notch characteristics for wireless local area network (WLAN) and dedicated short-range communication (DSRC) is proposed.
Abstract: In this paper, a compact ultra-wideband microstrip-fed annular ring antenna with band notch characteristics for wireless local area network (WLAN) and dedicated short-range communication (DSRC) is proposed. The proposed antenna comprises an annular ring patch and a partial ground plane with a rectangular slot. The notched frequency band is achieved by etching a partial annular slot in the lower portion of the ring radiator. The centre frequency and bandwidth of the notched band can be controlled by adjusting the width and position of the annular slot. Measured results show that the proposed antenna achieved an impedance bandwidth of 3{10.6GHz with a notched frequency band centred at 5.5GHz. Compared to the recently reported band-notched UWB antennas, the proposed antenna has a simple conflguration to realize the band notch characteristics to mitigate the possible interference between UWB and existing WLAN & DSRC systems. Furthermore, a symmetric radiation patterns, satisfactory gain and good time domain behaviour except at the notched frequency band makes the proposed antenna a suitable candidate for practical UWB applications.

Journal ArticleDOI
TL;DR: In this paper, a compact multi-band UHF Hilbert fractal antenna with wide frequency band and suitable size for easy installation was proposed for partial discharge (PD) detection in a transformer.
Abstract: Electromagnetic waves generated due to partial discharge (PD) can be captured by ultra-high-frequency (UHF) antennas. The size and frequency band of an UHF antenna for PD online monitoring are critical factors for practical installation inside a transformer. This paper presents a compact multi-band UHF Hilbert fractal antenna with wide frequency band and suitable size for easy installation. Design criteria of a PD antenna were proposed and the Hilbert fractal antenna was selected as an appropriate candidate for PD detection. Principle of Hilbert fractal antenna was discussed and a fourth order Hilbert fractal antenna was optimized for detecting PD signals. Actual PD experiments have been carried out for two typically artificial insulation defect models while the antenna was used for the PD measurement. More simulation studies and actual PD experiments have been done to further examine the effects of electromagnetic wave refraction and reflection by transformer components. The results show that the proposed UHF antenna is qualified for PD online monitoring.