Showing papers on "Frequency band published in 2019"
Patent•
AT&T1
TL;DR: In this paper, a communication device includes an antenna array configured to receive first millimeter wave (MMW) signals from a remote device in a mmWave frequency band and to transmit second mmw signals to the remote device.
Abstract: In accordance with one or more embodiments, a communication device includes an antenna array configured to receive first millimeter wave (MMW) signals from a remote device in a millimeter wave (MMW) frequency band and to transmit second millimeter wave (MMW) signals to the remote device in the MMW frequency band. A base transceiver station is configured to generate a consolidated steering matrix in accordance in a radio frequency (RF) band based on a consolidated feedback matrix in accordance with the RF band, wherein the MMW frequency band is above the RF band. A remote radio head is configured to: process the first MMW wave signals received from the remote device to recover an original feedback matrix in accordance with the MMW frequency band; convert the original feedback matrix in accordance with the MMW frequency band to the consolidated feedback matrix in accordance with the RF band; convert the consolidated steering matrix to a converted steering matrix that facilitates the transmission of the second MMW signals to the remote device in the MMW frequency band, and is further configured to generate the second MMW signals in accordance with the converted steering matrix.
210 citations
01 Nov 2019
TL;DR: In this paper, the authors proposed a channel-to-channel mapping in space and frequency, where the channels at one set of antennas and one frequency band are mapped to the channels from another set of antenna and frequency band.
Abstract: Can we map the channels at one set of antennas and one frequency band to the channels at another set of antennas— possibly at a different location and a different frequency bandƒ If this channel-to-channel mapping is possible, we can expect dramatic gains for massive MIMO systems. For example, in FDD massive MIMO, the uplink channels can be mapped to the downlink channels or the downlink channels at one subset of antennas can be mapped to the downlink channels at all the other antennas. This can significantly reduce (or even eliminate) the downlink training/feedback overhead. In the context of cell-free/distributed massive MIMO systems, this channel mapping can be leveraged to reduce the fronthaul signaling overheadIn this paper, we introduce the new concept of channel mapping in space and frequency, where the channels at one set of antennas and one frequency band are mapped to the channels at another set of antennas and frequency band. First, we prove that this channel-to-channel mapping function exists under certain conditions. Then, we leverage the powerful learning capabilities of deep neural networks to efficiently learn this non-trivial channel mapping function, which is also confirmed by the simulation results.
155 citations
TL;DR: In this article, a strategy to manipulate the electromagnetic wave with orthogonal circular polarizations based on a metasurface is proposed, which effectually breaks through traditional symmetrical characteristics between orthogonality.
Abstract: Polarization manipulation is a significant issue for artificial modulation of the electromagnetic (EM) wave, but general mechanisms all suffer the restriction of inherent symmetric properties between opposite handedness. Herein, a strategy to independently and arbitrarily manipulate the EM wave with orthogonal circular polarizations based on a metasurface is proposed, which effectually breaks through traditional symmetrical characteristics between orthogonal handedness. By synthesizing the propagation phase and geometric phase, the appropriate Jones matrix is calculated to obtain independent wavefront manipulation of EM waves with opposite circular polarizations. Two transmissive ultra-thin meta-deflectors are proposed to demonstrate the asymmetrical refraction of transmitted circularly polarized waves in the microwave region. Simulated transmitted phase front and measured far-field intensity distributions are in excellent agreement, indicating that the transmitted wave with different polarizations can be refracted into arbitrary and independent directions within a wide frequency band (relative bandwidth of 25%). The results presented in this paper provide more freedom for the manipulation of EM waves, and motivate the realizations of various polarization-independent properties for all frequency spectra.
128 citations
TL;DR: A joint time-frequency (TF) squeezing method and generalized demodulation (GD) to realize variable speed bearing fault diagnosis and has better performance than those methods based on conventional TF analysis and resampling.
Abstract: High-resolution time-frequency representation (TFR) method is effective for signal analysis and feature detection. However, for variable speed bearing vibration signal, conventional TFR method is prone to blur and affect the accuracy of the instantaneous frequency estimation. Moreover, the traditional order tracking, relying on equi-angular resampling, usually suffers from interpolation error. To solve such problems, we propose a joint time-frequency (TF) squeezing method and generalized demodulation (GD) to realize variable speed bearing fault diagnosis. The method can represent the time-varying fault characteristic frequency precisely and be free from resampling. First, using fast spectral kurtosis to select the optimal-frequency band which is sensitive to rolling bearing fault, and extracting envelope by Hilbert transform within the selected optimal frequency band. Next, a high-quality TF clustering method based on short-time Fourier transform is applied to the TF analysis of the envelope to get a clear TFR, from which the frequency information for GD is obtained. Finally, processing the basic demodulator via the peak search through the TF analysis results in the TFR for GD to gain a resampling-free-order spectrum. Based on the more precise TF information from the clearer TFR, the bearing fault can be diagnosed via GD without tachometer or any resampling involved, avoiding the amplitude error and low computational efficiency of resampling. Simulation study and experimental signal analysis validate that the proposed method has better performance than those methods based on conventional TF analysis and resampling.
104 citations
Posted Content•
TL;DR: In this paper, the fundamental elements and mechanisms associated with the Terahertz (THz) system architecture are analyzed and an up-to-date review paper is presented.
Abstract: Ultra-high bandwidth, negligible latency and seamless communication for devices and applications are envisioned as major milestones that will revolutionize the way by which societies create, distribute and consume information. The remarkable expansion of wireless data traffic that we are witnessing recently has advocated the investigation of suitable regimes in the radio spectrum to satisfy users' escalating requirements and allow the development and exploitation of both massive capacity and massive connectivity of heterogeneous infrastructures. To this end, the Terahertz (THz) frequency band (0.1-10 THz) has received noticeable attention in the research community as an ideal choice for scenarios involving high-speed transmission. Particularly, with the evolution of technologies and devices, advancements in THz communication is bridging the gap between the millimeter wave (mmW) and optical frequency ranges. Moreover, the IEEE 802.15 suite of standards has been issued to shape regulatory frameworks that will enable innovation and provide a complete solution that crosses between wired and wireless boundaries at 100 Gbps. Nonetheless, despite the expediting progress witnessed in THz wireless research, the THz band is still considered one of the least probed frequency bands. As such, in this work, we present an up-to-date review paper to analyze the fundamental elements and mechanisms associated with the THz system architecture.
102 citations
TL;DR: In this article, a new method for fault feature extraction of rolling bearing based on singular value decomposition (SVD) and frequency band entropy (OFBE) was proposed, which is based on the principle of maximum kurtosis.
96 citations
TL;DR: In this article, a simple and fast guideline is proposed to solve the problem of determining informative spectral frequency bands for generating enhanced/squared envelope spectra from spectral coherence for bearing fault diagnosis.
92 citations
TL;DR: An adaptive Kurtograms (AK) method is proposed, which improves the shortcomings of the center frequency and the bandwidth of the fast Kurtogram (FK) that cannot be explained theoretically.
86 citations
TL;DR: In this article, a multilayer structure and magnetic ferrite material are employed to expand the absorption bandwidth of 3-D frequency-selective rasorber (FSR), which achieved the sextuple bandwidth ratio with reflectivity less than −10 dB, and the absorption band with a bandwidth ratio of >2.6:1 can be achieved at either lower or upper absorption band, respectively.
Abstract: A multilayer structure and magnetic ferrite material are employed to expand the absorption bandwidth of 3-D frequency-selective rasorber (FSR). Resonant-like ferrite is used to realize the magnetic loss with high selectivity of absorption over a wide frequency band, while the multilayer structure is proposed to achieve multiple absorption peaks at designated frequencies. Combining the loaded ferrite material with multilayer structure can realize wide absorption bands. Equivalent circuit models are utilized to understand the operating mechanism of the described 3-D structure and to guide the design of multilayer structure with selected ferrite materials. Two broadband 3-D FSRs are designed, fabricated, and measured. Both designs achieve the sextuple bandwidth ratio with reflectivity less than −10 dB, and the absorption band with a bandwidth ratio of >2.6:1 can be achieved at either lower or upper absorption band, respectively.
82 citations
TL;DR: A distributed base station architecture in mm-wave is introduced as an approach to address increased handoff rate in UDN, and to provide an alternative way for network densification in a time and cost effective manner.
82 citations
TL;DR: In this paper, a stacked antenna array consisting of a lowerband antenna element working in 690-960 MHz frequency band and four upper-band antenna elements operating in the 3.5-4.9 GHz band is designed to demonstrate the concept.
Abstract: A novel stacked antenna configuration is proposed for the designs of shared-aperture base station antennas. An antenna array consisting of a lower-band antenna element working in 690–960 MHz frequency band and four upper-band antenna elements operating in the 3.5–4.9 GHz band is designed to demonstrate the concept. In the proposed configuration, four upper-band antenna elements are placed over the aperture of the lower-band antenna. Four metallic sheets are introduced to provide capacitive loading for the lower-band antenna and simultaneously offer a ground plane for the upper-band antennas. Therefore, low-profile characteristic and high isolations between the dual-band antennas are guaranteed. The overall height of the antenna array is only $0.17\lambda _{\text {L0}}$ ( $\lambda _{\text {L0}}$ is the free-space wavelength at the center frequency of the lower band), which is much lower than those of conventional designs. The measured results demonstrate that the designed antenna array achieves 32.7% and 33.3% impedance bandwidth in the lower and upper bands, respectively. High port isolations (>30 dB), high gains (>8 dBi), and stable radiation patterns are achieved in the two frequency bands. Owing to its simple structure and compact size, the resultant antenna array is easy for fabrication and is a promising candidate for sub-6 GHz band and 690–960 MHz band antennas.
TL;DR: In this paper, a miniaturized two-element microstrip antenna array is proposed for the millimeter-wave band of 5G wireless communication systems, where a surface of electromagnetic bandgap structures (EBG) is applied as the ground for two closely packed patch antennas operating in 5G New Radio (26,500, 29,500) frequency band.
Abstract: A miniaturized two-element microstrip antenna array is proposed for the millimeter-wave band of fifth generation (5G) wireless communication systems. A surface of electromagnetic bandgap structures (EBG) is applied as the ground for two closely packed patch antennas operating in 5G New Radio (26 500–29 500 MHz) frequency band. With the help of the proposed EBG ground, the two E-shaped microstrip antenna elements can be placed in close proximity to each other by 0.3 wavelength center to center distance in free space at the center frequency, yet the mutual coupling between them can still reach to more than 23 dB within the whole band of interest, which is about 10 dB larger than that on normal ground. All major radiation characteristics of the two-element array are well reserved with the EBG ground. The proposed design can be used in multiple-input-multiple-output applications or as the building subarray of larger phased arrays at millimeter-wave bands for mobile communication systems.
TL;DR: This work includes the first systematic assessment of the impact of the frequency sub-bands to the epileptic EEG classification accuracy, and the obtained results revealed several frequencySub-band combinations that achieve high classification accuracy and have never been reported in the literature before.
Abstract: The spectral information of the EEG signal with respect to epilepsy is examined in this study. In order to assess the impact of the alternative definitions of the frequency sub-bands that are analysed, a number of spectral thresholds are defined and the respective frequency sub-band combinations are generated. For each of these frequency sub-band combination, the EEG signal is analysed and a vector of spectral characteristics is defined. Based on this feature vector, a classification schema is used to measure the appropriateness of the specific frequency sub-band combination, in terms of epileptic EEG classification accuracy. The obtained results indicate that additional frequency band analysis is beneficial towards epilepsy detection. This work includes the first systematic assessment of the impact of the frequency sub-bands to the epileptic EEG classification accuracy, and the obtained results revealed several frequency sub-band combinations that achieve high classification accuracy and have never been reported in the literature before.
TL;DR: In this article, a band-notched UWB antenna with integrated Bluetooth is developed for personal wireless communication and UWB applications, which operates at the UWB frequency band (3.1-10.6 GHz) as well as Bluetooth (2.4-2.484 GHz).
Abstract: A compact band-notched UWB (Ultra-Wide Band) antenna with integrated Bluetooth is developed for personal wireless communication and UWB applications. The antenna operates at the UWB frequency band (3.1–10.6 GHz) as well as Bluetooth (2.4–2.484 GHz), with band-notch characteristics at the Wireless Local Area Network (WLAN) frequency band (5–6 GHz). A new technique of integrating Bluetooth within a UWB band-notched antenna is developed and analyzed. The UWB frequency band is realized by utilizing a conventional cylindrical radiating patch and a modified partial ground plane. The Bluetooth band is integrated using a miniaturized resonator with the addition of capacitors. Further, to mitigate the interference of the WLAN frequency band within the UWB spectrum, a conventional slot resonator is integrated within the radiator to achieve the task. The antenna is designed and fabricated, and its response in each case is provided. Moreover, the antenna exhibits a good radiation pattern with a stable gain in the passband. The present antenna is also compared to state-of-the-art structures proposed in the literature. The miniaturized dimensions (30 × 31 mm2) of the antenna make it an excellent candidate for UWB and personal wireless communication applications.
TL;DR: In this article, a dual-polarized frequency-reconfigurable low profile antenna with harmonic suppression for 5G application is presented, which consists of a pair of ±45° polarized frequency reconfigurable dipole antennas, two vertically placed feeding structures with filtering branches, and an artificial magnetic conductor (AMC) surface.
Abstract: A dual-polarized frequency-reconfigurable low-profile antenna with harmonic suppression for 5G application is presented in this letter. The proposed design consists of a pair of ±45° polarized frequency-reconfigurable dipole antennas, two vertically placed feeding structures with filtering branches, and an artificial magnetic conductor (AMC) surface. By introducing the U-shaped structure, a better impedance matching performance is achieved in two bands. Measured results show that the proposed antenna can operate at 3.24–4.03 and 4.44–5.77 GHz by controlling the on–off of PIN diodes, and port isolation of two bands is greater than 25 dB. What is more, two-octave harmonic suppression is realized by loading the filtering branches. In order to obtain stable unidirectional radiation pattern in the operating bands and low-profile characteristic, a dual-band 4 × 4 AMC reflector is fabricated. Finally, a maximum gain of 6.86 dBi in low frequency band and 8.14 dBi in high frequency band are obtained. Besides, the height of the proposed antenna is 0.1 λ at 3.3 GHz. Experimental results show that the antenna can meet the needs of the 5G communication.
TL;DR: It is shown for the first time how delayed interactions can excite the relevant set of eigenmodes that give rise to frequency specific functional connectivity patterns.
TL;DR: Results show that the main frequency band based on the computational method is a sensitive, accurate and efficient frequency parameter; it can accurately describe the frequency characteristics of blasting signals and effectively overcome the drawbacks in Fourier transform.
TL;DR: A new fault feature extraction method for rolling bearing combining EEMD and improved frequency band entropy (IFBE) is proposed, successfully applied to simulated data and actual data, which can accurately diagnose fault characteristics of bearing and prove the effectiveness and advantages of the method.
Abstract: Ensemble empirical mode decomposition (EEMD) is widely used in condition monitoring of modern machine for its unique advantages. However, when the signal-to-noise ratio is low, the de-noising function of it is often not ideal. Thus, a new fault feature extraction method for rolling bearing combining EEMD and improved frequency band entropy (IFBE) is proposed, i.e., EEMD–IFBE. According to the problem of multiple intrinsic mode functions (IMFs) generated by EEMD, how to select the sensitive IMF(s) that can better reflect fault characteristics, a novel method based on FBE for sensitive IMF is proposed. In addition, since the bandwidth parameter is set empirically when the band-pass filter is designed based on the original FBE, a novel bandwidth parameter optimization method based on the principle of maximum envelope kurtosis is proposed. First, the original vibration signal is subjected to EEMD to obtain a series of IMFs; Then, the FBE values are obtained for the original signal and each IMF component, and the bandwidth of the band-pass filter (empirically) is designed as the characteristic frequency band at the minimum entropy value, and the affiliation between the characteristic frequency band of each IMF and the characteristic frequency band of the original signal is compared, and then selecting the sensitive IMF(s) that reflects the characteristics of the fault; Third, due to the influence of background noise, it is difficult to accurately obtain the fault frequency from the selected IMF(s). Therefore, the band-pass filter designed based on FBE is used, and the bandwidth parameter is optimized based on the principle of envelope kurtosis maximum, and then the selected sensitive IMF is band-pass filtered. Finally, the envelope power spectrum analysis is performed on the filtered signal to extract the fault characteristic frequency, and then the fault diagnosis of the bearing is realized. The method is successfully applied to simulated data and actual data of rolling bearing, which can accurately diagnose fault characteristics of bearing and prove the effectiveness and advantages of the method.
TL;DR: This study aims to demonstrate the reduction in noise and vibration of an automobile dash panel structure by applying a locally resonant metamaterial (LRM) through an attachable local resonator (ALR).
TL;DR: The proposed metal-rim-integrated MIMO antenna array features small size, simple structure and wide bandwidth, and can be a good application-oriented design in next-generation 5G mobile communication.
Abstract: A wideband 8-antenna Multiple-Input Multiple-Output (MIMO) array covering 3.3-7.1 GHz for Fifth-Generation (5G) sub-7 GHz and New Radio Unlicensed (NR-U) applications in metal-rimmed smartphones is presented in this paper. In this design, the open slot loaded metal rim is directly fed by microstrip line. Hybrid Inverted-F Antenna (IFA) and slot modes are generated. Utilizing impedance matching and reactance loading, the two modes are moved and combined, so as to achieve size reduction and wideband coverage. The size of the ground slot (clearance) is only 12.4 mm × 1.5 mm (0.136 λ×0.016 λ at 3.3 GHz). The proposed MIMO antenna array is fabricated and measured. Results show that in the desired wide frequency band, the proposed design can achieve desirable antenna performances, including isolation >11 dB, total efficiency >47%, and calculated Envelope Correlation Coefficient (ECC) <; 0.09. Besides, antenna gain, radiation pattern and calculated ergodic channel capacity are demonstrated as well. The proposed metal-rim-integrated MIMO antenna array features small size, simple structure and wide bandwidth. It can be a good application-oriented design in next-generation 5G mobile communication.
TL;DR: A dynamic model of a flexible rotor system is established to simulate the rub- impact fault signal to help understand the dynamic characteristics of rub-impact fault signal, and a new time-frequency analysis algorithm termed as second order multi-synchrosqueezing transform is proposed, in which a second order two-dimensional instantaneous frequency estimation is embedded into a multi- synchrospezing framework.
TL;DR: The design of a multiport rectenna system for ambient radio frequency (RF) energy harvesting where the number of ports utilized is dependent on frequency, which allows the available area for the rectenna to be fully utilized at all frequencies.
Abstract: We describe the design of a multiport rectenna system for ambient radio frequency (RF) energy harvesting where the number of ports utilized is dependent on frequency. A unique aspect of the design is the use of different numbers of antenna ports for harvesting RF energy at different frequencies. This allows the available area for the rectenna to be fully utilized at all frequencies. In particular, the proposed antenna is designed to have four ports for harvesting energy from the GSM-900 frequency band and 12 ports for the GSM-1800 frequency band in the same area. The design for the rectifiers for the GSM-900 and GSM-1800 frequency bands with direct current (dc) combining is provided and prototypes are demonstrated. Field-test measurements show that the proposed rectenna can provide an output dc voltage of more than 3.2 V, an output dc power of more than −10 dBm, and an RF-to-dc efficiency of greater than 42% when the power density is greater than $1400~\mu \mathrm {W/m^{2}}$ . Measurements in an ambient RF environment at a university campus with commercial GSM-900 and GSM-1800 systems in operation show that the proposed rectenna can achieve output dc voltages of up to 2.2 V and dc power up to −13.6 dBm.
TL;DR: An improved Minimum Mean Square Error (MMSE) receiver is proposed for low-complexity Joint Equalization and CFO Compensation (JECC) in frequency domain using Banded-Matrix Implementation (BMI).
Abstract: Orthogonal Frequency Division Multiplexing (OFDM) based on Non-Orthogonal Multiple Access (NOMA) has been previously studied to fulfil the demands of high spectral efficiency, massive connectivity and resilience to frequency selectivity for the upcoming fifth generation (5G) wireless communication and beyond. NOMA enables spectrum overlapping and allows distinct users to simultaneously operate over the same frequency band, and thus enables massive connectivity. High Peak-to-Average Power Ratio (PAPR) and sensitivity to Carrier Frequency Offset (CFO) are significant demerits to deploy such a multicarrier system for 5G and beyond applications. This paper studies the problem of high PAPR and the presence of CFO with efficient pre-coding techniques and a very simplified receiver design. An improved Minimum Mean Square Error (MMSE) receiver is proposed for low-complexity Joint Equalization and CFO Compensation (JECC) in frequency domain using Banded-Matrix Implementation (BMI). Moreover, we have investigated the sensitivity of different pre-coding techniques to channel and CFO estimation errors.
TL;DR: In this article, a reflectarray for generating wideband circularly polarized (CP) orbital angular momentum (OAM) vortex wave in the X-band was proposed, where a dual linearly polarized (LP) element consisting of two rhombus-shaped metal patches etched on two dielectric substrates was designed.
Abstract: A reflectarray for generating wideband circularly polarized (CP) orbital angular momentum (OAM) vortex wave in the X -band is proposed. First, a dual linearly polarized (LP) element consisting of two rhombus-shaped metal patches etched on two dielectric substrates is designed. The element has high isolations between two polarizations and preferable linear phase responses in wide frequency band. Then, the phase distribution of the reflectarray carrying the OAM vortex wave with mode l = 1 is designed, and dimensions of the elements are determined by their reflective phases. The far-field radiation patterns and near-field phase distributions are simulated to verify the proposed design. Finally, prototype of a 313-element reflectarray with an LP Vivaldi feed, which converts an incident LP wave into a reflective CP wave, is fabricated and measured. The results of measurement indicate that the reflectarray can generate CP OAM vortex wave with mode l = 1 in 9–11 GHz band (a fractional bandwidth of 20%). The reflectarray also achieves 20% 1 dB gain bandwidth, and its peak gain is 19.9 dB at 11 GHz. Except for a very narrow band (10.9–11.1 GHz), its measured 3 dB axial-ratio bandwidth is about 40%.
TL;DR: The proposed adaptive frequency band selection technique utilizing the Harmonic Significance Index (HSI) and Particle Swarm Optimization (PSO) is proposed in this paper and confirms the effectiveness of the proposed technique for bearing fault diagnosis.
TL;DR: Frequency band extraction based on frequency slice wavelet transform (FSWT) shows significant advantage on observed frequency band selection, which could be highly suitable to extract early fault transient signals within a resonant frequency band.
TL;DR: In this paper, a polarization independent conformal wideband metamaterial absorber has been proposed, which consists of a circle and a slotted sector with four lumped resistors between them to improve the absorption bandwidth.
Abstract: A polarization independent conformal wideband metamaterial absorber has been proposed in this study. The proposed absorber unit cell consists of a circle and a slotted sector, loaded with four lumped resistors between them to improve the absorption bandwidth. Measured and simulated results exhibit more than 90% absorption in the frequency band from 3.90 GHz to 10.5 GHz under the normal incidence angle, and the fractional bandwidth is 91.6%. The proposed absorber is polarization independent due to the symmetrical nature. The absorber unit cell is compact in configuration with a unit cell size of 0.16 λo × 0.16 λo, where λo is the wavelength at 3.9 GHz and the substrate thickness is 0.098 λo. Once the proposed absorber is wrapped on the cylindrical surface, it shows good absorptivity in the absorption frequency band. The effects of many designed parameters have been studied to understand the performance of the wideband absorber. To recognize the absorption phenomenon of the absorber, normalized impedance, electric field distribution, and surface current density have been demonstrated. Finally, the proposed conformal absorber fabricated and measured the absorption for flat and curved surfaces, which exhibits good agreement between the simulated and the experimental results.
TL;DR: In this article, the authors proposed an optically transparent transmit array antenna (TA) in the 27.5-29.5 GHz frequency band, which is composed of meshed double-circle rings printed on polymethylmethacrylate substrates.
Abstract: This letter presents a transmitarray antenna (TA) in the 27.5–29.5 GHz frequency band. The proposed TA is optically transparent and offers the possibility of steering the beam in the H -plane from –30° to 30°. One can achieve these properties using a novel unit cell, composed of meshed double-circle rings printed on polymethylmethacrylate substrates, a plastic material transparent to visible light. This unit cell provides a phase shift of 300° for an insertion loss lower than 1 dB at 28.5 GHz. In turn, the TA sources consist of 2 × 2-element arrays of aperture-coupled stacked patch antennas. The choice of a patch array over a horn array allows one to reduce the total profile and weight of the TA. We have fabricated and tested a transparent TA with a diameter of 9.9 wavelengths at 28.5 GHz, yielding a broadside gain of 25 dBi and –1 dB gain bandwidth of 1.8 GHz; the off -axis 30° beam presents a peak gain of 21.5 dBi and –1 dB gain bandwidth of 1.4 GHz. The measured results are in good agreement with the simulated ones all over the frequency band of interest.
TL;DR: In this paper, a dual-band valley-Hall topological insulator (VH-PTI) was demonstrated in a microwave substrate-integrated circuitry, where the topological kink states exist at two separated frequency bands, and the simulated and experimental results demonstrate that the dualband PTI is robust against sharp bends of the internal domain wall with negligible inter-valley scattering.
Abstract: Extensive researches have revealed that valley, a binary degree of freedom (DOF), can be an excellent candidate of information carrier. Recently, valley DOF has been introduced into photonic systems, and several valley-Hall photonic topological insulators (PTIs) have been experimentally demonstrated. However, in the previous valley-Hall PTIs, topological kink states only work at a single frequency band, which limits potential applications in multiband waveguides, filters, communications, and so on. To overcome this challenge, here we experimentally demonstrate a valley-Hall PTI, where the topological kink states exist at two separated frequency bands, in a microwave substrate-integrated circuitry. Both the simulated and experimental results demonstrate the dual-band valley-Hall topological kink states are robust against the sharp bends of the internal domain wall with negligible inter-valley scattering. Our work may pave the way for multi-channel substrate-integrated photonic devices with high efficiency and high capacity for information communications and processing.
TL;DR: A method that accurately identifies the optimal frequency band even with complicated interferences from the motor and industrial field is presented, and the resonance frequency band excited by the motor bearing fault is located.
Abstract: Bearing faults are the main contributors to the failure of motors. Periodic harmonic components from the motor rotating and random impulses caused by the electromagnetic interference heavily trouble vibration-based resonance demodulation techniques. This paper presents a method that accurately identifies the optimal frequency band even with complicated interferences from the motor and industrial field. Singular value negentropy (SVN) is originally applied to measure the periodicity of signal without prior knowledge. Based on the SVN, periodicity-impulsiveness spectrum (PIS) that simultaneously takes periodicity and impulsiveness of fault impulses into consideration is constructed. Guided by the period-oriented kurtosis selection criterion, the resonance frequency band excited by the motor bearing fault is located. The proposed method was validated by the simulated motor bearing signal and the real datasets. Compared with the most popular resonance demodulation methods, kurtogram and protrugram, the proposed method is undoubtedly an alternative method for the identification of optimal resonance band.