Showing papers on "Frequency band published in 2018"
TL;DR: A survey of the mmWave propagation characteristics, channel modeling, and design guidelines, such as system and antenna design considerations for mmWave, including the link budget of the network, which are essential for mm Wave communication systems design is presented.
Abstract: The millimeter wave (mmWave) frequency band spanning from 30 to 300 GHz constitutes a substantial portion of the unused frequency spectrum, which is an important resource for future wireless communication systems in order to fulfill the escalating capacity demand. Given the improvements in integrated components and enhanced power efficiency at high frequencies, wireless systems can operate in the mmWave frequency band. In this paper, we present a survey of the mmWave propagation characteristics, channel modeling, and design guidelines, such as system and antenna design considerations for mmWave, including the link budget of the network, which are essential for mmWave communication systems. We commence by introducing the main channel propagation characteristics of mmWaves followed by channel modeling and design guidelines. Then, we report on the main measurement and modeling campaigns conducted in order to understand the mmWave band’s properties and present the associated channel models. We survey the different channel models focusing on the channel models available for the 28, 38, 60, and 73 GHz frequency bands. Finally, we present the mmWave channel model and its challenges in the context of mmWave communication systems design.
512 citations
TL;DR: A new indicator, Combined Squared Envelope Spectrum, is employed to consider all the frequency bands with valuable diagnostic information and to improve the fault detectability of the Autogram, and a thresholding method is also proposed to enhance the quality of the frequency spectrum analysis.
224 citations
TL;DR: Numerical simulations demonstrate that the radar transmitted power can be efficiently reduced by exploiting the communication signals scattered off the target at the radar receiver, and it is shown that the robust waveforms bound the worst-case power-saving performance of radar system for any target spectra in the uncertainty sets.
Abstract: This paper considers the problem of power minimization-based robust orthogonal frequency division multiplexing (OFDM) radar waveform design, in which the radar coexists with a communication system in the same frequency band. Recognizing that the precise characteristics of target spectra are impossible to capture in practice, it is assumed that the target spectra lie in uncertainty sets bounded by known upper and lower bounds. Based on this uncertainty model, three different power minimization-based robust radar waveform design criteria are proposed to minimize the worst-case radar transmitted power by optimizing the OFDM radar waveform, which are constrained by a specified mutual information requirement for target characterization and a minimum capacity threshold for communication system. These criteria differ in the way the communication signals scattered off the target are considered: 1) as useful energy, 2) as interference, or 3) ignored altogether at the radar receiver. Numerical simulations demonstrate that the radar transmitted power can be efficiently reduced by exploiting the communication signals scattered off the target at the radar receiver. It is also shown that the robust waveforms bound the worst-case power-saving performance of radar system for any target spectra in the uncertainty sets.
214 citations
TL;DR: In this paper, a plate structure is proposed to demonstrate the pseudospin Hall effect for flexural waves, which can be used to guide low-frequency, spin-dependent one-way flexural wave along a desired path with bends.
Abstract: Inspired by the quantum spin Hall effect shown by topological insulators, we propose a plate structure that can be used to demonstrate the pseudospin Hall effect for flexural waves. The system consists of a thin plate with periodically arranged resonators mounted on its top surface. We extend a technique based on the plane-wave expansion method to identify a double Dirac cone emerging due to the zone-folding in frequency band structures. This particular design allows us to move the double Dirac cone to a lower frequency than the resonating frequency of local resonators. We then manipulate the pattern of local resonators to open subwavelength Bragg band gaps that are topologically distinct. Building on this method, we verify numerically that a waveguide at an interface between two topologically distinct resonating plate structures can be used for guiding low-frequency, spin-dependent one-way flexural waves along a desired path with bends.
148 citations
TL;DR: This paper provided better frequency bands and channels reference for emotion recognition based on EEG and found the classification accuracy of the gamma frequency band is greater than that of the beta frequency band followed by the alpha and theta frequency bands.
Abstract: Background Many studies have been done on the emotion recognition based on multi-channel electroencephalogram (EEG) signals. Objective This paper explores the influence of the emotion recognition accuracy of EEG signals in different frequency bands and different number of channels. Methods We classified the emotional states in the valence and arousal dimensions using different combinations of EEG channels. Firstly, DEAP default preprocessed data were normalized. Next, EEG signals were divided into four frequency bands using discrete wavelet transform, and entropy and energy were calculated as features of K-nearest neighbor Classifier. Results The classification accuracies of the 10, 14, 18 and 32 EEG channels based on the Gamma frequency band were 89.54%, 92.28%, 93.72% and 95.70% in the valence dimension and 89.81%, 92.24%, 93.69% and 95.69% in the arousal dimension. As the number of channels increases, the classification accuracy of emotional states also increases, the classification accuracy of the gamma frequency band is greater than that of the beta frequency band followed by the alpha and theta frequency bands. Conclusions This paper provided better frequency bands and channels reference for emotion recognition based on EEG.
133 citations
Patent•
AT&T1
TL;DR: In this paper, an analog surface wave repeater pair includes a first launcher configured to transmit and receive first guided electromagnetic waves that propagate on an outer surface of a first segment of a transmission medium.
Abstract: In accordance with one or more embodiments, an analog surface wave repeater pair includes a first launcher configured to transmit and receive first guided electromagnetic waves that propagate on an outer surface of a first segment of a transmission medium. A second launcher is configured to transmit and receive second guided electromagnetic waves that propagate on an outer surface of a second segment of the transmission medium. A first transceiver includes a first notch filter is configured to attenuate signals in a fourth generation (4G) wireless frequency band from the first microwave signal generated by the first launcher in response to receiving the first guided electromagnetic waves. A second transceiver includes a second notch filter configured to attenuate signals in the fourth 4G wireless frequency band from a second microwave signal generated by the second launcher in response to receiving the second guided electromagnetic waves.
123 citations
TL;DR: In this paper, a decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array.
Abstract: A decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array. The MTM-EMBG structure is cross-shaped assembly with fractal-shaped slots etched in each arm of the cross. The fractals are composed of four interconnected-`Y-shaped' slots that are separated with an inverted-`T-shaped' slot. The MTM-EMBG structure is placed between the individual patch antennas in a 2 × 2 antenna array. Measured results show the average inter-element isolation improvement in the frequency band of interest is 17, 37 and 17 dB between radiation elements #1 & #2, #1 & #3, and #1 & #4, respectively. With the proposed method there is no need for using metallic-via-holes. The proposed array covers the frequency range of 8-9.25 GHz for X-band applications, which corresponds to a fractional-bandwidth of 14.5%. With the proposed method the edge-to-edge gap between adjacent antenna elements can be reduced to 0.5λ
0
with no degradation in the antenna array's radiation gain pattern. Across the array's operating band, the measured gain varies between 4 and 7 dBi, and the radiation efficiency varies from 74.22 and 88.71%. The proposed method is applicable in the implementation of closely-packed patch antenna arrays used in SAR and MIMO systems.
121 citations
TL;DR: The simulation results have shown that the proposed multi-modal cooperative spectrum sensing can achieve better sensing performance in fading channel.
Abstract: In 5G-based cognitive radio, the primary user signal is more active due to the broad frequency band. The traditional cooperative spectrum sensing only detects one characteristic of PU using one kind of detector, which may decrease the sensing performance when the wideband PU is in severe fading channel. In this paper, a multi-modal cooperative spectrum sensing is proposed to make an accurate decision through combining multi-modal sensing data of the PU signal, such as energy, power spectrum, and signal waveform. Each secondary user (SU) deploys multiple kinds of detectors, such as energy detector, spectral detector and waveform detector. The multi-modal sensing data from different detectors are sent to a fusion center. In the fusion center, the local decision is achieved through the Bayesian fusion, while the global decision is determined by the DS fusion. The sensing credibility of each detector can be fully considered in the DS fusion, in order to avoid the performance difference of different detectors. Weight DS fusion is also proposed to improve the decision performance through decreasing the sensing impact of malicious SU while increasing the fusion proportion of dominant SU. The simulation results have shown that the proposed multi-modal cooperative spectrum sensing can achieve better sensing performance in fading channel.
115 citations
TL;DR: In this paper, the authors proposed a high scanning rate leaky-wave antenna (LWA) based on a slow-wave substrate integrated waveguide (SIW) structure, which is introduced by etching periodical slots on the top surface of SIW.
Abstract: In this communication, we propose a high scanning rate leaky-wave antenna (LWA) based on a slow-wave substrate integrated waveguide (SIW) structure. The slow-wave effect is introduced by etching periodical slots on the top surface of SIW. The LWA radiation is subsequently realized by introducing sinusoidal modulation to the slots profile. Such a structure significantly improves the scanning rate of LWA due to the small group velocity at the slow-wave region. Simulation and measured results indicate that the proposed LWA scans a wide angle in a narrow bandwidth near the cutoff frequency of surface plasmon polariton. Within the frequency band 13.5–13.9 GHz (3% relative bandwidth), the measured scanning angle is from 2° to 37° with the measured gain all above 9.2 dBi.
112 citations
TL;DR: In this article, a robust and deterministic approach to design metasurfaces to achieve polarization-independent diffusive scatterings of electromagnetic (EM) waves within an ultrabroad frequency band and for wide-range of incident angles is proposed.
Abstract: Diffusive scatterings of electromagnetic (EM) waves by a thin screen are important in many applications, but available approaches cannot ensure uniform angular distributions of low-intensity scatterings without time-consuming optimizations. Here, we propose a robust and deterministic approach to design metasurfaces to achieve polarization-independent diffusive scatterings of EM waves within an ultrabroad frequency band and for wide-range of incident angles. Our key idea is to use high-efficiency Pancharatnam–Berry meta-atoms to form subarrays exhibiting focusing reflection-phase profiles, that can guarantee nearly uniform diffusive scatterings for arbitrarily polarized EM waves. As an illustration, we design and fabricate two metasurfaces and experimentally characterize their wave-diffusion properties in C, X, and Ku bands. Theoretical, numerical and experimental results demonstrate that our approach can diffuse the incident energy much more uniformly than available approaches based on the uniform-phase s...
108 citations
TL;DR: One-dimensional, non-linear, nanoelectromechanical lattices (NEML) with active control of the frequency band dispersion in the radio-frequency domain (10–30 MHz), inspired by NEMS-based phonon waveguides, and includes the voltage-induced frequency tuning of the individual resonators.
Abstract: Nanoelectromechanical systems (NEMS) that operate in the megahertz (MHz) regime allow energy transducibility between different physical domains. For example, they convert optical or electrical signals into mechanical motions and vice versa. This coupling of different physical quantities leads to frequency-tunable NEMS resonators via electromechanical non-linearities. NEMS platforms with single- or low-degrees of freedom have been employed to demonstrate quantum-like effects, such as mode cooling, mechanically induced transparency, Rabi oscillation, two-mode squeezing and phonon lasing. Periodic arrays of NEMS resonators with architected unit cells enable fundamental studies of lattice-based solid-state phenomena, such as bandgaps, energy transport, non-linear dynamics and localization, and topological properties, directly transferrable to on-chip devices. Here we describe one-dimensional, non-linear, nanoelectromechanical lattices (NEML) with active control of the frequency band dispersion in the radio-frequency domain (10–30 MHz). The design of our systems is inspired by NEMS-based phonon waveguides and includes the voltage-induced frequency tuning of the individual resonators. Our NEMLs consist of a periodic arrangement of mechanically coupled, free-standing nanomembranes with circular clamped boundaries. This design forms a flexural phononic crystal with a well-defined bandgap, 1.8 MHz wide. The application of a d.c. gate voltage creates voltage-dependent on-site potentials, which can significantly shift the frequency bands of the device. Additionally, a dynamic modulation of the voltage triggers non-linear effects, which induce the formation of a phononic bandgap in the acoustic branch, analogous to Peierls transition in condensed matter. The gating approach employed here makes the devices more compact than recently proposed systems, whose tunability mostly relies on materials’ compliance and mechanical non-linearities.
TL;DR: In this paper, a novel ultra-wideband terahertz absorber by using periodic arrays of graphene disks and ribbons is proposed and analyzed using analytical expressions for the input impedance of the proposed structure.
TL;DR: In this article, the authors presented the complete design of a wideband transmit-array (TA) antenna with high gain and high efficiency for D-band applications based on the low-temperature co-fired ceramic technology.
Abstract: This paper presents the complete design of a wideband transmit-array (TA) antenna with high gain and high efficiency for D-band applications based on the low-temperature co-fired ceramic technology. The proposed unit cell is composed of a pair of wideband magnetoelectric dipoles as the receive/transmit elements, together with a substrate-integrated waveguide (SIW) aperture-coupling transmission structure for independent phase adjustability. A 360° phase coverage is obtained by the proposed phasing element, and its phase response curves are nearly parallel within a broad frequency band, which indicates a wideband performance. To verify the design, the fabricated prototype is measured by using a vector network analyzer in a terahertz compact-range anechoic chamber. The measured peak gain is 33.45 dBi at 150 GHz with the aperture efficiency of 44.03%, and the measured 3 dB gain bandwidth is 124–158 GHz (24.29%). The good radiation performance ensures that the proposed SIW aperture-coupling TA antenna is a promising candidate for D-band applications.
TL;DR: In this paper, a gap waveguide-based compact monopulse array antenna, which is formed with four unconnected layers, was designed for millimeter-wave tracking applications at 85-105 GHz.
Abstract: This paper presents a gap waveguide-based compact monopulse array antenna, which is formed with four unconnected layers, for millimeter-wave tracking applications at $W$ -band (85–105 GHz). Recently developed gap waveguide technology removes the need for galvanic contact among metallic layers of waveguide structures, and thereby, makes the proposed antenna suitable for easy and low-cost manufacturing. In this context, a low-loss planar Magic-Tee is designed to be used in a monopulse comparator network consisting of two vertically stacked layers. The gap waveguide planar monopulse comparator network is integrated with a high-efficiency $16\times 16$ corporate-fed slot array antenna. The measured results of the comparator network show the amplitude and phase imbalance values to be less than 0.5 dB and 2°, respectively, over the frequency band of interest. The fabricated monopulse array antenna shows relative impedance bandwidths of 21% with input reflection coefficients better than −10 dB for the sum and difference ports. The null in the difference radiation pattern is measured to be 38 dB below the peak of the sum radiation pattern at 94 GHz. The measured gain is about 30 dBi for the same frequency. The low-loss performance of the comparator network and the feed network of the proposed array, together with the simple and easy manufacturing and mechanical assembly, makes it an excellent candidate for $W$ -band compact direction-finding systems.
TL;DR: In this paper, an elastic magnifier was used to amplify base excitation and provide sufficient kinetic energy to overcome potential well barriers, thus leading to large-amplitude bistable motion.
TL;DR: A compact metamaterial inspired antenna operate at LTE, Bluetooth and WiMAX frequency band is introduced in this paper and is applicable for LTE andWiMAX applications.
Abstract: A compact metamaterial inspired antenna operate at LTE, Bluetooth and WiMAX frequency band is introduced in this paper. For the lower band, the design utilizes an outer square metallic strip forcing the patch to radiate as an equivalent magnetic-current loop. For the upper band, another magnetic current loop is created by adding metamaterial structure near the feed line on the patch. The metamaterial inspired antenna dimension of 42 × 32 mm2 compatible to wireless devices. Finite integration technique based CST Microwave Studio simulator has been used to design and numerical investigation as well as lumped circuit model of the metamaterial antenna is explained with proper mathematical derivation. The achieved measured dual band operation of the conventional antenna are sequentially, 0.561~0.578 GHz, 2.346~2.906 GHz, and 2.91~3.49 GHz, whereas the metamaterial inspired antenna shows dual-band operation from 0.60~0.64 GHz, 2.67~3.40 GHz and 3.61~3.67 GHz, respectively. Therefore, the metamaterial antenna is applicable for LTE and WiMAX applications. Besides, the measured metamaterial antenna gains of 0.15~3.81 dBi and 3.47~3.75 dBi, respectively for the frequency band of 2.67~3.40 GHz and 3.61~3.67 GHz.
TL;DR: This paper demonstrates an adjustable circuit for harvesting from LTE 700-MHz, GSM 850- MHz, and ISM 900-MHz bands with one single circuit, fabricated on printed circuit board with comprehensive evaluations at each associated frequency to test the power conversion efficiency (PCE).
Abstract: Ambient radio frequency (RF) energy harvesting (RF-EH) allows powering low-power electronic devices without wires, batteries, and dedicated energy sources. Current RF-EH circuit designs for ambient RF harvesting are optimized and fabricated for a predetermined frequency band. Thus, a single circuit is tuned for a given band with simple extensions to multiple circuits operating individually in distinct bands. Our approach is different in the sense that it designs and implements a common circuit design that can operate on multiple different RF cellular and ISM bands. This paper makes two contributions. First, it presents a study of ambient RF signal strength distribution conducted in Boston, MA, USA, indicating locations and associated RF bands that can point toward the practicality of ambient RF-EH. Second, it demonstrates an adjustable circuit for harvesting from LTE 700-MHz, GSM 850-MHz, and ISM 900-MHz bands with one single circuit. Our circuit design is fabricated on printed circuit board with comprehensive evaluations at each associated frequency to test the power conversion efficiency (PCE). In addition, we characterize the charging performance, and feasibility of powering sensors outdoors such as TI eZ430-RF2500. Results reveal more than 45% PCE for our prototype.
TL;DR: In this article, the authors proposed a very compact dual-band-notched ultrawide band (UWB) multiple-input multiple-output (MIMO) antenna.
Abstract: This study describes the design of a very compact dual-band-notched ultrawide band (UWB) multiple-input multiple-output (MIMO) antenna. The main features of the proposed antenna are its compact dimensions and high isolation between the two antenna elements. The UWB performance of the antenna is attained by designing two identical triangular-shaped patch elements, which are designed opposite to each other and connected to a tapered microstrip feedline. The ground plane of the proposed antenna consists of a funnel-shaped patch connected with two triangles at the lower end. In addition, two J-shaped slits are etched in the radiator to get the band rejection characteristics at wireless local area network band from 5.1 to 5.8 GHz and IEEE INSAT/Super-Extended C-band from 6.7 to 7.1 GHz. The designed antenna has the smallest dimension of
. Results show that the MIMO antenna has a large impedance bandwidth of 31.9 GHz from 3.1 to 35 GHz. The diversity performance of the proposed antenna is also analysed using different parameters such as envelope correlation coefficient (ECC), diversity gain, total active reflection coefficient and so on. Due to the low mutual coupling of <−24 dB and ECC of <0.2 across the frequency band this antenna is a good candidate for portable UWB applications.
TL;DR: Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.
Abstract: Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement. Based on the conventional triangular patch antenna, two more resonances can be obtained with the introduction of multiple parasitic patches, and consequently, the antenna bandwidth can be broadened. Parametric analysis of the patches has been studied for the verification of bandwidth enhancement. An example of the proposed antenna with multiple parasitic patches is designed, fabricated, and tested. The measured bandwidth with $\vert S_{11}\vert dB ranges from 5.46 to 6.27 GHz (13.8%), and good far-field radiation patterns can be obtained within the frequency band. In addition, two shorting vias are inserted into the above proposed antenna to decrease the input impedance, resulting in further bandwidth enhancement of the antenna. This antenna is fabricated and tested as well, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.
TL;DR: In this article, a dual-polarized high-isolation multiple input multiple output (MIMO) antenna array for wideband base-station applications is presented, where the antenna array consisting of four elements is working within the frequency band from 2.4 to 3 GHz and decoupling branches among the elements are introduced to improve the isolation by about 10 dB.
Abstract: A low-profile dual-polarized high-isolation multiple input multiple output (MIMO) antenna array for wideband base-station applications is presented in this paper. The proposed dual-polarized antenna element has the advantage of lower profile ( $0.067\lambda $ ) by utilizing artificial magnetic conductor structure. The antenna array consisting of four elements is working within the frequency band from 2.4 to 3 GHz. Furthermore, decoupling branches among the elements are introduced to improve the isolation by about 10 dB. Both simulation and measured results indicate that the proposed dual-polarized antenna element has a good isolation over 28 dB. Moreover, the beamwidth of the antenna array can be effectively broadened by the adjustment of phase distributions of corresponding artificial material plane. Finally, a larger MIMO system is also investigated, and the simulation and measured results prove that dual-polarized dipole antenna MIMO array has good system performance.
09 Apr 2018
TL;DR: This paper provides a simple, yet accurate absorption model, which can be utilized to predict the absorption loss at the above frequency band and is shown to be very accurate below one kilometer link distances.
Abstract: This paper focuses on giving a simplified molecular absorption loss model for a 275–400 GHz frequency band, which has significant potential for variety of future short and medium range communications. The band offers large theoretical data rates with reasonable path loss to theoretically allow even up to kilometer long link distances when sufficiently high gain antennas are used. The molecular absorption loss in the band requires a large number of parameters from spectroscopic databases, and, thus, the exact modeling of its propagation characteristics is demanding. In this paper, we provide a simple, yet accurate absorption model, which can be utilized to predict the absorption loss at the above frequency band. The model is valid at a regular atmospheric pressure, it depends on the distance, the relative humidity, and the frequency. The existing simplified model by ITU does not cover frequencies above 350 GHz and has more complexity than our proposed model. The molecular absorption loss increases exponentially with the distance, decreasing the utilizable bandwidth in the vicinity of the absorption lines. We provide a model to approximate the window widths at the above frequency band. This model depends on the distance, the relative humidity, the frequency, and the maximum tolerable loss. It is shown to be very accurate below one kilometer link distances.
TL;DR: A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling and the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are improved by considerable amounts.
Abstract: In this paper, a method to reduce the inevitable mutual coupling between antennas in an extremely closely spaced two-element MIMO antenna array is proposed. A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling. The meta-surface is equivalent to a negative permeability medium, along which wave propagation is rejected. By properly designing the rejection frequency band of the SRR unit, the mutual coupling between the antenna elements in the MIMO antenna system can be significantly reduced. Two prototypes of microstrip antenna arrays at 5.8 GHz band with and without the metasurface have been fabricated and measured. The matching bandwidths of antennas with reflection coefficient smaller than −15 dB for the arrays without and with the metasurface are 360 MHz and 900 MHz respectively. Using the meta-surface, the isolation between elements is increased from around 8 dB to more than 27 dB within the band of interest. Meanwhile, the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are also improved by considerable amounts. All the results demonstrate that the proposed method is very efficient for enhancing the performance of MIMO antenna arrays.
TL;DR: In this article, a checkerboard metasurface based on a novel physical mechanism, optimized multielement phase cancellation, is proposed for greatly expanding the bandwidth of radar cross section (RCS) reduction.
Abstract: In this paper, a checkerboard metasurface based on a novel physical mechanism, optimized multielement phase cancellation, is proposed for greatly expanding the bandwidth of radar cross section (RCS) reduction. More basic metaparticles and, in particular, the variable phase difference between them, greatly increase the ability to control electromagnetic waves. Interactions between multiple local waves produced by the basic metaparticles at multiple frequencies sampled in a superwide frequency band are manipulated and optimized simultaneously to achieve phase cancellation. The proposed metasurface can achieve a 10 dB RCS reduction in a superwide frequency band from 5.5 to 32.3 GHz with a ratio bandwidth ( ${f}_{H}/{f}_{L}$ ) of 5.87:1 under normal incidence for both polarizations. Furthermore, the RCS reduction is larger than 8 dB from 5.4 to 40 GHz with a ratio bandwidth of 7.4:1. The metasurface also has a good performance under wide-angle oblique incidences. The optimal metaparticle distribution is found to obtain the superwideband bistatic RCS reduction. The theoretical analysis, simulation, and experimental results are in good agreement and verify the ability and capability of the proposed mechanism.
TL;DR: In this paper, a dual-polarized patch antenna element fed by a pair of antisymmetric L-shaped probes is proposed, which is able to introduce feed capacitance to the antenna for broadband operation.
Abstract: A dual-polarized patch antenna element fed by a pair of antisymmetric L-shaped probes is proposed. The designed twin L-shaped probe feeding structure is able to introduce feed capacitance to the antenna for broadband operation. The lengths of the two L-shaped probe feeds are identical, but the feeds are antisymmetric. This feeding design can minimize the unwanted radiation from the probe effectively. The dual-polarized antenna can be operated in the frequency band 1580–2750 MHz, which covers the current mobile communication systems, 3G and 4G and higher band frequencies. A prototype with dual slanted ±45° polarization has been fabricated for validation. Both the simulation and measured results show that the proposed antenna has wide bandwidth of 54% (SWR < 2) with desirable directional radiation patterns in the vertical and horizontal planes, as well as high isolation better than −30 dB between the two input ports.
TL;DR: In this article, a broadband polarization-reconfigurable Fabry-Perot (FP) resonator antenna is presented for WLAN/WiMAX applications, which achieves a broadband 3dB gain bandwidth by designing the PRS layer to have a reflection phase with positive slope over as wide a frequency band as possible.
Abstract: In this letter, a broadband polarization-reconfigurable Fabry–Perot (FP) resonator antenna is presented for WLAN/WiMAX applications. The open air-filled FP cavity is constructed by a partially reflective surface (PRS) layer directly placed over a fully reflective ground plane. A two-element patch array is employed to serve as a feeder. To achieve polarization reconfigurability, the feeding antenna is designed to have the capability of switching between horizontal linear polarization (HP) and vertical linear polarization (VP) by controlling the on/off states of four pairs of p-i-n diodes. By combining the frequency resonances of the FP cavity and the feeding antenna, the proposed FP resonator antenna obtains broadband performance. Furthermore, the proposed antenna achieves a broadband 3 dB gain bandwidth by designing the PRS layer to have a reflection phase with positive slope over as wide a frequency band as possible. The proposed antenna was fabricated and experimentally characterized. Measurements demonstrate that it achieves a −10 dB impedance bandwidth of 21 $\%$ ranging from 2.2 to 2.72 GHz, which can well cover WLAN/WiMAX band of operation. The 3 dB gain bandwidths of 12.5 $\%$ and 14.6 $\%$ are obtained with peak realized gains of 15.1 and 14.8 dBi for the HP and VP, respectively.
TL;DR: In this article, a four-element reconfigurable annular slot-based multiple-input-multiple-output (MIMO) antenna system integrated within an ultrawideband (UWB) sensing antenna is presented.
Abstract: This communication presents a novel integrated antenna system for cognitive radio (CR) applications. The design consists of a compact four-element reconfigurable annular slot-based multiple-input-multiple-output (MIMO) antenna system integrated within an ultrawideband (UWB) sensing antenna. All the antenna elements are planar in structure and designed on a single substrate ( RO-4350 ) with dimensions $60\times 120\times 1.5$ mm3. The frequency reconfigurable slot-based MIMO antenna system is tuned over a wide frequency band from 1.77 to 2.51 GHz while the UWB sensing antenna is covering from 0.75 to 7.65 GHz The proposed antenna system is suitable for CR enabled wireless devices. The envelop correlation coefficient did not exceed 0.248 in the entire operating band of the MIMO antenna part. The maximum measured gain of the MIMO antenna is 3.2 dBi with a maximum efficiency of 81%.
TL;DR: In this article, a self-powered flexible piezoelectric acoustic sensor (f-PAS) inspired by basilar membrane in human cochlear was presented, which covered the voice frequency spectrum via the combination of its low quality (Q) factor and multi-resonant frequency tuning, exhibiting four to eight times higher sensitivity than the conventional condenser sensor.
TL;DR: In this article, the use of a dispersive prism with a triangular shape is proposed to reduce the dispersive radiation nature of a leaky-wave antenna (LWA) in groove-gap waveguide technology.
Abstract: In this paper, the use of a dispersive prism with a triangular shape is proposed to reduce the dispersive radiation nature of a leaky-wave antenna (LWA) in groove-gap waveguide technology. The operation of gap waveguide technology is based on the use of metallic pins that act as an artificial magnetic conductor, so the electromagnetic fields are confined and guided in the desired directions. To control a leaky-wave radiation of these confined fields is possible by tailoring the height of the pins, its periodicity, and the waveguide width. This radiation, as in any conventional LWA, is dispersive, leading to beam squint as the frequency is varied. Here, we mitigate this beam squint by using a prism made of dispersive pins and choosing appropriately their periodicity and height. With this prism, the leaky-wave radiation is focused into one single direction in a wide frequency band. This concept is demonstrated with a prototype designed to radiate at $\varphi =41^\circ $ with a central frequency of 12 GHz and the high gain of 16.5 dBi. A 22% frequency bandwidth for the 3 dB realized gain at $\varphi =41^\circ $ is achieved, and the main radiating direction, with half-power beamwidth of 5°, steers only ±0.5° from 11.4 to 13.4 GHz.
TL;DR: In this article, a modulation signal bispectrum (MSB) based robust detector for bearing fault detection is proposed, which allows effective suppression of both stationary random noise and discrete aperiodic noise.
TL;DR: In this paper, a design of a wideband and high-gain circularly polarized (CP) extended hemispherical lens antenna for millimeter-wave applications is presented, which can transfer an incident wave from linear to CP over the wide operating bandwidth.
Abstract: This communication presents a design of a wideband and high-gain circularly polarized (CP) extended hemispherical lens antenna for millimeter-wave applications. The proposed lens integrated with a dielectric polarizer can transfer an incident wave from linear to CP over the wide operating bandwidth. This design is different from the cascaded design of a polarizer with an extended hemispherical dielectric lens. In this design, only one device is required to achieve dual functions. Therefore, size reduction and loss reduction can be obtained. Besides, thanks to the low-cost 3-D printed technology, the polarizer can be fabricated in an accurate and convenient way. A theoretical analysis is carried out. Equations are derived based on refraction law. For demonstration, the proposed CP lens antenna is implemented and measured. This antenna achieves a wide impedance bandwidth of 27% from 51 to 67 GHz for the reflection coefficient <−10 dB and a wide axial ratio (AR) bandwidth of 29% from 50 to 67 GHz for the AR <3 dB. The gain of the antenna can reach to 21 dBic, which agrees with our analysis. The ultimate goal of this communication is to develop a wideband, high-gain, small size and low-cost lens antenna for the millimeter-wave frequency band.