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The integration of multi-standard and multi-band wireless communication system will be the development trend of mine communication. The mine wireless repeater is an important part of the mine communication system. However, the antenna suitable for wireless repeaters is a vertical whip antenna, which greatly limits the size of the antenna in the horizontal direction. In this paper, an ultra-narrow size slotted sleeve antenna is proposed for the RF front end of wireless repeaters for underground mining. The antenna design process can be divided into three steps. First, a flag shaped slot is cut in the rectangular sleeve to increase the impedance bandwidth of the antenna. Second, the reverse branch is loaded on the top of the sleeve, which ingeniously increases the resonant path of the antenna. Moreover, a T-shaped slot is etched on the transmission line, which further improves the overall performance of the antenna. The electrical size of the antenna with this unique structural design is only 0.41λ × 0.048λ, which is much smaller than the lateral size of similar antennas. The simulation and measurement results of the proposed antenna are in good agreement, and the working bands include 0.79–0.82 GHz, 1.42–1.47 GHz, 2.39–2.59 GHz, 2.63–2.91 GHz, and 5.10–5.75 GHz. [ABSTRACT FROM AUTHOR]

In this paper, based on bionics, a flexible multi-band antenna is designed to mimic the structure of a spider's web, which supports various communication standards such as 4G, 5G, and GPS. The antenna lays out multiple loop branches in a limited space to achieve wideband operations from 1.31 GHz to 2 GHz (42.4%), from 3.4 GHz to 4 GHz (16.2%), and from 5.1 GHz to 5.78 GHz (12.5%). The antenna selects 40 × 50 × 0.1 mm³ polyimide as the dielectric substrate and trapezoidal coplanar waveguide feed. A simulation and experimental analyses demonstrate that the antenna exhibits consistent performance when subjected to different bending scenarios. The design scheme utilizing a flexible dielectric substrate streamlines the integration process, offering a promising avenue for deployment in smart wireless devices. The results of the consistent tests and simulations demonstrate that the device meets the requisite standards for wireless communication. [ABSTRACT FROM AUTHOR]

This paper presents a novel double-sided structure multi-band antenna that cleverly combines a Koch snowflake structure with a hexagonal fractal structure; the front of the antenna features a right semicircle minus a half-order Koch snowflake structure, while the back of the antenna showcases a left semicircle minus half of a hexagonal fractal snowflake structure, which are combined together to form a complete circle. The antenna can cover common communication bands such as fourth to fifth generation (5G) commercial bands, ISM, WLAN, and Bluetooth. The structure of the radiator portion of the antenna is designed by iteratively scaling a basic arc shape multiple times based on a certain scale factor, and after simulation and comparison, three iterations can achieve the best antenna performance, and the antenna uses a microstrip line transmission to broaden the antenna bandwidth. The antenna covers three effective frequency bands: 2.38–2.90 GHz (20.3%), 3.35–3.85 GHz (14.1%), and 5.06–5.80 GHz (13.5%). The antenna dielectric sheet is made of RF-35 from Taconic, which has the advantages of high strength, complete surface inertness, and a long service life, with a dielectric constant of 3.5 and actual dimensions of 50 mm × 54 mm × 0.76 mm. The antenna is fractal-iterated in small dimensions, and the approximation of the frequency bands is accomplished by comparing the ratios of each iteration with the current vector map. The antenna was simulated by HFSS software (Version 21). and measured in an electromagnetic anechoic chamber, and the test results were consistent with the simulation results. [ABSTRACT FROM AUTHOR]

This paper presents a partially-grounded dual-band compact patch antenna with high selectivity for 2.4 GHz and 6.4 GHz wireless communication systems. The design concept is to achieve the 2.4 GHz resonance by using a simple patch, then introducing a U-shaped slot at the patch to grant the 6.4 GHz resonance. In order to minimize the design geometry without effecting the antenna performance, a center square cut-out is inserted into the center of the patch with two other cut-outs etched out from the upper part of the patch. For the selectivity enhancement, the partial ground plane is presented and studied. The proposed antenna reveals good performance and both bands can be independently controlled by tuning and adjusting various parts of the antenna. The proposed antenna is designed on a Rogers RT5880 substrate with thickness of 1.57 mm and overall dimension of 30x30 mm2 using CST-MW package and the simulated results are verified experimentally with very good agreement between the two approaches. The impedance bandwidths are 0.4 GHz and 0.2 GHz at 2.4 GHz and 6.4 GHz, respectively. The gains of the proposed antenna are 1.2 dB and 1.21 dB, respectively with return loss of -37.70 dB and 36.90 dB, respectively. The proposed dual-band compact antenna exhibits omni-directional radiation patterns and achieves a better gain in comparison to monopole antennas. [ABSTRACT FROM AUTHOR]

The increasing need for swift, low-latency, and reliable wireless transmission in the age of 5G has led to rapid advancements in 5G technology. MIMO systems, originally implemented in 4G applications, remain an integral part of 5G networks. The sub-6-GHz frequency band holds promise for 5G applications, such as improved link and reduced transmission losses. This comprehensive review explores advancements in patch antenna (PA) structure for sub-6 GHz 5G smartphone utilization, addressing the challenges posed by space constraints in mobile devices and the need for efficient integration of antennas. The paper discusses the significance of MIMO antennas in modern cellular communication, particularly in the context of 5G technology, which utilizes sub-6 GHz. Reconfigurable antennas (RAs) and Microstrip Patch Antennas (MPAs) are introduced as solutions, highlighting their compact, cost-effective, and flexible nature. The review delves into critical factors such as geometry, substrate selection, and feed design in optimizing patch antenna performance. It also covers the importance of addressing both sub-6 GHz and mm-wave bands within a single antenna system. [ABSTRACT FROM AUTHOR]

In this paper, an ultra-thin logo antenna (LGA) operating in multiple frequency bands for Internet of Vehicles (IoVs) applications was proposed. The designed antenna can cover five frequency bands, 0.86–1.01 GHz (16.0%) for LoRa communication, 1.3–1.36 GHz (4.6%) for GPS, 2.32–2.71 GHz (16.3%) for Bluetooth communication, 3.63–3.89 GHz (6.9%) for 5G communication, and 5.27–5.66 GHz (7.1%) for WLAN, as the simulation indicated. The initial antenna started with a modified coplanar waveguide (CPW)-fed circular disk monopole radiator. To create extra current paths and further excite other modes, the disk was hollowed out into the shape of the car logo of the Chinese smart EV brand XPENG composing four rhombic parasitic patches. Next, four triangular parasitic patches were inserted to improve the impedance matching of the band at 5.6 GHz. Finally, four metallic vias were loaded for adjusting resonant points and the return loss reduction. Designed on a flexible substrate, the antenna can easily bend to a certain degree in complex vehicular communication for IoV. The measured results under horizontal and vertical bending showed the LGA can operate in a bending state while maintaining good performance. The proposed LGA addresses the issue of applying one single multi-band antenna to allow vehicles to communicate over several channels, which relieves the need for a sophisticated antenna network. [ABSTRACT FROM AUTHOR]

The MIMO antenna is one of the essential elements for the implementation of the new fifth-generation (5 G) technologies. The design of the MIMO antenna goes through several steps; the important one is the design of the single-element antenna that resonates at the desired frequency band(s). Its design becomes more difficult if it is a multi-band antenna. In addition, determining the dimensions of multi-band antennas by simulation or mathematical models is both more complicated, difficult, and time-consuming. In this research, different approaches based on artificial neural networks (ANN), radial basis function neural networks (RBFNN), and adaptive neuro-fuzzy inference systems (ANFIS) are used to predict the dimensions of a dual-band circular patch antenna with defected ground structure (DGS) for mm-wave 5 G applications, and then the performances of the three models are compared. To determine the training and the testing data, 280 antennas with different patch values and added slots in the ground plane are simulated. The resonant frequencies of the dual-band circular patch antenna and the height of the substrate are used as the input vector for the ANN, RBFNN, and ANFIS models. Two hundred twenty simulated antennas were used for training, and the remaining 60 data points were used to test the ANN, RBFNN, and ANFIS models. The performance of these models is compared in the training and testing process using some statistical criteria such as MSE, MAE, and RMSE. The proposed dual-band circular patch single-element antenna has a compact size of 5 × 6 × 0.8 m m 3 and exhibits good performance, such as broad band (3.8 and 3 GHz), high gain (6 and 7.1 dB), and high efficiency (99 % and 95 % ) in both operating bands. After studying the single-element antenna and in order to improve its performance, we proposed a 4 × 4 MIMO antenna with a total volume of 17 × 17 × 0.8 m m 3 that was designed by using four copies of the single-element antenna arranged orthogonally on the same low-loss Rogers Duroid 5880 substrate. The suggested 4 × 4 MIMO antenna achieves a high level of isolation (more than - 30 dB in both operating bands), which is obtained by inserting a cross-shaped decoupling structure among elements on the upper and lower sides of the substrate. Moreover, the proposed MIMO antenna has a good gain of 6.4 and 7.5 dB in both bands and a high radiation efficiency of 99.5 % and 99 % at 28 and 38 GHz, respectively. Furthermore, the diversity performance of the MIMO antenna is evaluated using a variety of crucial indicators, all of which greatly surpass realistic norms. The envelope correlation coefficient (ECC) is less than 0.005, the diversity gain (DG) is greater than 9.99 dB, the total active reflection coefficient (TARC) is below 10 dB, and the channel capacity loss (CCL) is no longer than 0.4 bits/s/Hz. In addition, the proposed dual band circular patch single element antenna and the 4 × 4 MIMO antenna are fabricated, and the measured results are in good agreement with the simulated results using HFSS and CST software. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a multi-band acoustic topological insulator based on the Valley Hall effect is designed. Based on the mirror symmetry in the C 3 v point group phononic crystal, by changing the parameters of the primitive cell, the phononic crystal simultaneously has multiple linear Dirac degenerate points at the K point of the Brillouin zone, which can realize multi-band topology valley transmission. The whole triangular multi-band acoustic topological valley insulator system has C 3 v symmetry. By rotating the clover-like scatterer, the mirror symmetry of the structure can be broken, thereby opening the degeneracy at the Dirac point. The energy band is reversed at the K point, realizing the Valley Hall phase transition. By connecting different structural systems, boundary states are constructed to simulate topologically protected edge acoustic transmission. Different phonon crystal structures are further constructed, and their acoustic transmission characteristics are verified by finite element algorithms. This paper can provide guidance for the design and engineering application of multi-band acoustic antennas, acoustic logic control gate circuits, and other functional devices for acoustic communication. [ABSTRACT FROM AUTHOR]

A compact coplanar waveguide-fed monopole antenna is presented in this paper. The proposed antenna is composed of three monopole branches. In order to achieve the miniaturization, the longest branch was bent. The antenna is printed on an FR4 dielectric substrate, having a compact size of 0.144λ0 × 0.105λ0 × 0.003λ0 at its lowest resonant frequency of 900 MHz. The multiband antenna covers five frequency bands: 820–990 MHz, 1.87–2.08 GHz, 2.37–2.93 GHz, 3.98–4.27 GHz, and 5.47–8.9 GHz, which covers the entire radio frequency identification bands (860–960 MHz, 2.4–2.48 GHz, and 5.725–5.875 GHz), Global System for Mobile Communications (GSM) bands (890–960 MHz and 1.850–1.990 GHz), WLAN bands (2.4–2.484 GHz and 5.725–5.825 GHz), WiMAX band (2.5–2.69 GHz), X-band satellite communication systems (7.25–7.75 GHz and 7.9–8.4 GHz), and sub 6 GHz in 5G mobile communication system (3.3–4.2 GHz and 4.4–5.0 GHz). Also, the antenna has good radiation characteristics in the operating band, which is nearly omnidirectional. Both the simulated and experimental results are presented and compared and a good agreement is established. The proposed antenna operates in five frequency bands with high gain and good radiation characteristics, which make it a suitable candidate in terminal devices with multiple communication standards. [ABSTRACT FROM AUTHOR]

In this paper, a highly efficient tree-shaped fractal antenna with multi-broadband resonance characteristics is proposed. The proposed antenna exhibits broad operating bandwidth, high gain, and high efficiency characteristics due to the suggested modifications in the antenna geometry. The suggested circular patch is modified by introducing slots in the form of a tree-shaped fractal structure, and the partial ground plane is modified by incorporating a narrow rectangular slot. The proposed antenna is designed on an FR4 substrate of 4 0 × 2 5. 0 5 × 1. 6 mm3. The prototype of the proposed antenna has been fabricated and tested to justify the simulation results. The measurement results are in good agreement with the simulation that validates the multi-broadband design approach of the proposed fractal antenna. As per the measurement results, the proposed antenna operates at four distinct bands with − 10 dB impedance bandwidths of 600 MHz (2.2–2.8) GHz, 1070 MHz (3.3–4.37) GHz, 2550 MHz (4.75–7.3) GHz, and 2200 MHz (9.7–11.9) GHz. Furthermore, a high peak gain of 10.23 dB and a peak radiation efficiency of 96.65% are recorded for the suggested fractal antenna. The suggested compact bandwidth enhanced multi-band antenna can be useful for several wireless communication systems such as wireless fidelity (Wi-Fi), wireless local area network (WLAN), Bluetooth, long-term evolution (LTE), C, S and X bands. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a novel multi-tracks wideband and multi-band miniaturized antenna design for implanted medical devices biomedical telemetry is proposed. This antenna entirely covers seven frequency bands which are the bands (401-406) MHz of the Medical Device Radiocommunications Service (MedRadio), the three bands (433.1-434.8), (868.0-868.6), and (902.8-928.0) MHz of the Industrial, Scientific, and Medical (ISM), and the three bands (608-614) MHz, and (1.395-1.400) and (1.427-1.432) GHz of theWireless Medical Telemetry Service (WMTS). The antenna possesses a compact full size of (19.5 × 12.9 × 0.456) mm3. The antenna miniaturization and impedance bandwidth enhancement are achieved using two techniques: the patch slotting and insertion of open-end slots in the ground plane, respectively. Prototype of proposed antenna with multi-tracks has been fabricated and tested in free space. The comparison between the simulated and measured reflection coefficient has been done and found in good agreement with each other. Furthermore, simulations of the proposed antenna implanted in the underneath the scalp in a realistic human model shows a wideband operation from 0.19 to 0.94 GHz, and from 1.38 to 1.54 GHz corresponding to return loss (S11 = -10 dB). Link budget calculation is performed to specify the range of telemetry considering both Specific Absorption Rate (SAR) restrictions and effective isotropic radiated power (EIRP) limitations. The designed implantable antenna with full ground plane presents an appropriate reflection coefficient for muscle implantation. Furthermore, the designed implanted muscle antenna may be also suitable for skin implantation. [ABSTRACT FROM AUTHOR]

This manuscript presents a compact multi-band antenna with simple and small geometry dedicated to the millimeter-wave 5G wireless systems. The single antenna has been carefully designed on Rogers RT5880 laminate with a full dimension of 5 × 6 × 0.8 mm3 and studied using CST microwave studio software. A fabricated prototype has been made and tested to assess the simulation results where a very good agreement has been noted. The measurement revealed that the antenna covers the frequency bands of 23.99–24.187, 25.712–26.218 and 27.761–28.361 GHz resonating at 24.1, 26 and 28 GHz, where their corresponding gain are 6.4, 6.72 and 6.65 dB respectively. In addition, the antenna is featured with a stable radiation patterns and a maximum efficiency of 93%, which express high radiation performance. The antenna equivalent circuit has been also studied where the reflection coefficient achieved is in good accord with the simulated one. Furthermore, to fight the strong path loss at the mmWave spectrum, the single antenna element has been employed to propose a new three-dimensional phased array for 5G mobile phones using four edge-mounted subarrays each is composed of 10-elements and exhibits high gain of 16.1 dB. The subarrays altogether provide a robust coverage of 180° in both elevation and azimuth planes, while a full-coverage of 360° has been attained in the phi-plane using beamsteering technique. Besides, an extreme isolation greater than 50 dB is attained between the subarrays. The attained results prove that the proposed antenna could highly fit the 5G mobile phone applications. [ABSTRACT FROM AUTHOR]

In this paper, a compact reconfigurable tri-band/quad-band monopole antenna is presented. To achieve the multi-band behavior, two right-angled triangles were etched in a conventional rectangular patch, and a partial ground plane is used. Moreover, the proposed multi-band antenna is printed on a low cost FR4 epoxy with compact dimensions of 0.23 λ 0 × 0. 2 3 λ 0 × 0. 0 1 2 λ 0 , where λ 0 is calculated at the lowest resonance frequency. To provide frequency agility, a metal strip which acts as PIN diode was embedded in the frame of the modified patch. The tri-band/quad-band antenna performance in terms of reflection coefficient, radiation patterns, peak gain and efficiency was studied. The measured results are consistent with the simulated results for both cases. The simple structure and the compact size of the proposed antenna could make it a good candidate for multi-band wireless applications. [ABSTRACT FROM AUTHOR]

This article proposes and designs a multi‐band antenna that imitates banana leaves structurally. The edge structure of the antenna radiator is a mirror‐symmetrical trapezoid, and four patches of different sizes are used as leaf veins inside. The feeding mode is coplanar waveguide feeding with a trapezoidal structure. The electromagnetic simulation software HFSS is used for antenna modeling and parameter optimization. The test results show that the antenna can cover 0.79 to 3.18 GHz, 3.29 to 3.98 GHz, and 4.98 to 7.62 GHz and produce six main frequency points: 0.9, 1.5, 2.4, 3.8, 5.6, and 6.9 GHz. The antenna has omnidirectional radiation characteristics and can be widely used in the future mobile communication network coverage field. [ABSTRACT FROM AUTHOR]

Futuristic communication in sub 6-GHz demands a compact antenna with multi-band resonance. This would be necessary to cater to the need in LTE, Wireless Fidelity, and 5G applications. A compact microstrip inverted slotted antenna for the future sub 6 -GHz wireless and mobile applications employs an important role in the present scenario. In this investigation, a slotted antenna especially for multi-band mobile applications in sub 6-GHz is presented. The slotted rectangular patch is matched with a microstrip offset feed line and stub matching. The performance of the single-layer slotted antenna is significantly improved using a slotted SRR structure. The designed antenna shows good reflections co-efficient at 3 GHz and 4 GHz with good return loss. The antenna exhibits impedance bandwidth up to 200 MHz and peak gain up to 4 dBi. It finds its application at the precise frequency for mobile wireless communication in LTE and sub 6-GHz for future 5G applications. [ABSTRACT FROM AUTHOR]

In this study, multi‐band antenna for LTE wearable device with shared slots and radiators for smart watch was present. This study incorporated 4G communication frequency bands, a GPS positioning system, and BT/Wi‐Fi in a 43.6 × 43.6 × 5.8 mm3 metal case to achieve satisfactory radiation fields and performance efficiency within a small space. This article presents an overview of the theory. There are four ports in the system. Frist, Port 1 is a low‐frequency antenna offering LTE 700 and GSM 850/900. The maximal gain and efficiency are respectively 3.9 dBi and 82%. Second, Port 2 is a high‐frequency monopole with a winding long path on the side of the frame to achieve a reflection loss bandwidth that fully encompasses GSM 1800/1900/UMTS and LTE 2300/2500. The maximal gain and efficiency of this port are respectively 5.3 dBi and 92%. There are also have GPS (Port 3) and Wi‐Fi (Port 4) antenna implement IFA and loop excitation mechanisms, respectively. This antenna system can fulfill the market demand. As confirmed through both simulation and measurement, the antenna can cover LTE bands. Increasing the path capacity of a MIMO system to increase the transmission speed is a crucial focus in mobile communication research and development. [ABSTRACT FROM AUTHOR]

A compact, wide dual-band antenna designed to resonate at 2.25 GHz and 5.4 GHz is proposed in this paper. The proposed antenna is a monopole rectangular patch designed to operate at 5 GHz. This basic structure is modified by introducing a metamaterial-based interdigital capacitor reactive loading that exhibits dual-band characteristics at 2.25 GHz and 5.4 GHz. A bandwidth greater than 1.4 GHz at the two resonant frequencies is obtained. The compact size of the proposed antenna is 0.0989λ0 × 0.0498λ0 where λ0 is calculated at the first resonance. The antenna is etched on a FR4 substrate with dielectric constant εr = 4.4 and thickness of 1.6 mm. The simulated results exhibit considerable gain and wide impedance bandwidth at the resonant frequencies. Monopole-like radiation patterns are obtained at both the operating frequencies. The designed antenna can be applied in wireless local area networks and Wi-MAX wireless communications. [ABSTRACT FROM AUTHOR]

A novel design of compact, linearly polarized and low-profile planar antenna which is electrified by Substrate Integrated Waveguide (SIW) resonator has been developed for multi-band applications of X-band spectrum. Radiating patch has been excited through two closely spaced longitudinal apertures of identical length but non-identical width, incorporated in SIW resonator. These apertures are responsible for multiple operating bands. The achieved fractional bandwidths are 1.29 %, 0.49 % and 1.60 % having resonant frequencies at 10.07 GHz, 10.85 GHz and 11.82 GHz respectively for |S11| ≤ -10 dB. The measured peak gain for first, second and third operating band is 6.54 dB, 6.86 dB and 7.68 dB respectively. The proposed antenna is a highly selective antenna for various applications of X-band microwave spectrum. This band has been particularly selected for military communication because it provides a trade-off between the characteristics (i. e. interference and rain resilience, data rates and remote coverage) of different frequency bands which are particularly suited to the needs of military users. It is very much suitable for secure communication i. e. to deny unauthorized access to sensitive unclassified information and prevent disruption of telecommunication. A comparative analysis of antenna's parameters has been examined by Ansys HFSS and results are verified through experimental outcomes. [ABSTRACT FROM AUTHOR]

In this paper, we propose a topological acoustic waveguide which can transmit high-precision and multiband sound energy with backscattering suppression and no energy loss. It is a kind of acoustic waveguide with spatial lattice uniformity without destroying lattice position. This acoustic structure is obtained by integrating two kinds of multi-stage resonators arranged in a triangular lattice pattern in the air environment. On one hand, the introduction of internal modes greatly improves the transmission accuracy of topological acoustic waveguide compared with the Bragg scattering alone under the same overall structure size. On the other hand, it greatly improves the utilization rate of the internal space of the structure and makes full use of the multi-modal in structure to construct more sound transmission bands. After introducing the rotational scattering mechanism, the numerical and experimental results show that up to seven high-precision acoustic transmission channels with backscattering suppression and no energy loss below 14 kHz are obtained along the sonic crystal interface with different topological states in this topological acoustic waveguide. This research paves the way for engineering applications of high-precision acoustic transmission, multi-band acoustic antennas, acoustic logic control, covert sound transmission and other multifunctional acoustic devices. [ABSTRACT FROM AUTHOR]

A 30-mW multi-band receiver based on harmonic selection is presented. The prototype receiver employs a 32-phase non-overlapping local oscillator (LO) and is capable of simultaneously receiving multiple wireless signals arbitrarily located between 600 MHz and 3 GHz. The receiver achieves 2.4–5-dB noise figure (NF) and tolerates as large as −10-dBm out-of-band blockers. Employing a digital harmonic rejection (HR) calibration to overcome phase and amplitude mismatches in the 32-phase LO and down-conversion paths, close to 80 dB of HR is measured. [ABSTRACT FROM AUTHOR]

Abstract Terahertz (THz) absorbers due to the high potential of providing reliable applications in modern devices and technology are increasingly being investigated. Recently, a dual-band THz absorber based on a graphene sheet and ribbons has been proposed in which the results were obtained using Full-wave simulations and its authors have not provided any specific design method. In this work, we have proposed and investigated that tunable THz absorber by its circuit model. A developed transmission line method beside the analytical circuit model of graphene continues sheet and periodic arrays of graphene ribbons are used to obtain analytical expressions for the circuit model. Here, first of all, we have compared the results of the proposed method with the results of that paper and secondly, using impedance matching concept we have proposed multi-band tunable THz absorber with near-unity absorption by the same structure. Then, we have compared the results of our circuit method with the Full-wave simulations. In either case, our proposed method in addition to excellent performance in terms of runtime and memory sources, has an acceptable agreement with the results of the Full-wave simulations. The proposed method is general and can be applied to design and simulate the other sub-wavelength structures. [ABSTRACT FROM AUTHOR]

The multi-band UWAS (Underwater Wireless Acoustic Sensor) communication techniques are effective in terms of performance and throughput efficiency because they can overcome selective frequency fading by allocating the same data to different frequency bands, in an environment of rapidly changing channel transfer characteristic. However, the multi-band configuration may have a performance worse than the single-band one because performance degradation in one particular band affects the output from all the other bands. This problem can be solved by using a receiving end that analyzes the error rates of each band, sets threshold values and allocates the lower weights to the inferior bands. There are many methods of setting threshold values. In this paper, we proposed an algorithm to set the threshold value by using the preamble error rates, which are known data that have to be transmitted and received. In addition, we have analyzed the efficiency of multi-band transmission scheme in the UWAS communication by applying 1~4 number of multi-bands, using turbo pi codes, with a coding rate of 1/3. We evaluated the performance of the proposed multi-bands transmission model in real underwater environments. Experimental results showed that the performance increased as the number of multiple bands increased. Furthermore, the performance of multi-band was improved when the proposed threshold algorithm was applied. [ABSTRACT FROM AUTHOR]

In order to improve the intelligibility and quality of speech signal under different noise environments, an improved multi-band spectral subtraction algorithm using Mel-scale is proposed in this paper. In this algorithm, the whole speech spectrum is divided into N subbands without overlapping each other using the Mel frequency domain, and uses spectral subtraction to obtain the estimated pure speech independently in each subband. By using various types of noise at various SNRs, the experimental data, including SNR, PESQ measure and non-professional hearing test, are obtained. The result show that the algorithm is superior to the multi-band spectral subtraction with uniform segmentation and the traditional spectral subtraction algorithm, without causing considerable signal distortion and remnant musical noise. [ABSTRACT FROM AUTHOR]

In this letter, a compact size multiband metamaterial based antenna with circular polarization property is presented. A metamaterial unit cell consist of four thin strips that constitute the modified square split ring resonator (MSSRR) which each of strips generate negative refraction index in antenna's resonant frequency modes. The proposed antenna operate at Bluetooth (2400-2484 MHz specified by IEEE 802.11b/g), WiMAX (3.3-3.6 GHz specified by IEEE 802.16) and C-band (4-8 GHz) while circular polarization feature is obtained at these operational bands. The total size of antenna is 20 × 20 × 1.5 mm and realized on FR4-epoxy substrate. The design concept was confirmed by fabrication of the antenna scheme and measuring its characteristics. The extracted results show the antenna exhibits good agreement with simulation ones. [ABSTRACT FROM AUTHOR]

In this paper, an artificial stereo extension method that creates stereophonic sound from a mono sound source is proposed. The proposed method first trains deep neural networks (DNNs) that model the nonlinear relationship between the dominant and residual signals of the stereo channel. In the training stage, the band-wise log spectral magnitude and unwrapped phase of both the dominant and residual signals are utilized to model the nonlinearities of each sub-band through deep architecture. From that point, stereo extension is conducted by estimating the residual signal that corresponds to the input mono channel signal with the trained DNN model in a sub-band domain. The performance of the proposed method was evaluated using a log spectral distortion (LSD) measure and multiple stimuli with a hidden reference and anchor (MUSHRA) test. The results showed that the proposed method provided a lower LSD and higher MUSHRA score than conventional methods that use hidden Markov models and DNN with full-band processing. [ABSTRACT FROM AUTHOR]

In this paper, a chiral metamaterial consisting of bi-layered metasurface with double F-shaped resonators is investigated. We experimentally demonstrate that this new structure can realize multi-band asymmetric transmission of a linearly polarized wave in the microwave region. The simulated results also show that the structure can achieve multi-band 90° polarization rotator for a y-polarized wave. The mechanisms of coupling modes are analyzed by the current distribution at different resonant frequencies, which indicates that the cross-polarized transmission is due to both the electric coupling and the magnetic coupling. Furthermore, the polarization conversion ratios (PCRs) with more than 90 % conversion efficiency of x-polarized and y-polarized waves are also studied based on the optical activity and electric field distributions. [ABSTRACT FROM AUTHOR]

In this paper, the design, fabrication, and measurements of a compact ultrathin five-band metamaterial absorber with wide-angle stability have been presented. The unit cell of the absorber consists of five concentric metallic circular rings printed as the top layer of a grounded dielectric substrate of thickness 1 mm. The radii and the intermediate gap between the rings are optimized such that the proposed absorber exhibits five distinct absorption peaks at frequencies of 5.28, 7.36, 9.52, 12.64, and 16.32 GHz with absorptivities of 92.03, 90.46, 95.10, 91.65, and 91.10%, respectively. The proposed absorber is polarization insensitive for both TE and TM incident wave and results high absorption for wide incidence angle up to 60°. The proposed structure is compact with its unit cell size of 0.54λ0and ultrathin with thickness of ~λ0/19 corresponding to the highest frequency of absorption. Surface current and field distributions are studied to understand the absorption mechanism. A prototype of the proposed absorber is fabricated and experimentally tested for different polarization and incident angles. The measured results are observed to be in agreement with the simulated ones. The proposed absorber is suitable for potential applications due to its multi-band absorption. [ABSTRACT FROM AUTHOR]

In this paper, a multi-band enabled femtocell base station (FCBS) and user equipment (UE) architecture is proposed in a multi-tier network that consists of small cells, including femtocells and picocells deployed over the coverage of a macrocell for splitting uplink and downlink (UL/DL) as well as control-plane and user-plane (C-/U-plane) for 5G mobile networks. Since splitting is performed at the same FCBS, we define this architecture as the same base station based split architecture (SBSA). For multiple bands, we consider co-channel (CC) microwave and different frequency (DF) 60 GHz millimeter wave (mmWave) bands for FCBSs and UEs with respect to the microwave band used by their over-laid macrocell base station. All femtocells are assumed to be deployed in a 3-dimensional multi-storage building. For CC microwave band, cross-tier CC interference of femtocells with macrocell is avoided using almost blank subframe based enhanced inter-cell interference coordination techniques. The co-existence of CC microwave and DF mmWave bands for SBSA on the same FCBS and UE is first studied to show their performance disparities in terms of system capacity and spectral efficiency in order to provide incentives for employing multiple bands at the same FCBS and UE and identify a suitable band for routing decoupled UL/DL or C-/U-plane traffic. We then present a number of disruptive architectural design alternatives of multi-band enabled SBSA for 5G mobile networks for UL/DL and C-/U-plane splitting, including a disruptive and complete splitting of UL/DL and C-/U-plane as well as a combined UL/DL and C-/U-plane splitting, by exploiting dual connectivity on CC microwave and DF mmWave bands. The outperformances of SBSA in terms of system level capacity, average spectral efficiency, energy efficiency, and control-plane overhead traffic capacity in comparison with different base stations based split architecture (DBSA) are shown. Finally, a number of technical and business perspectives as well as key research issues of SBSA are discussed. [ABSTRACT FROM AUTHOR]

A new center-fed tri-band reflectarray antenna is presented in this paper. Elements of the reflectarray antenna are circular rings and patches loaded with slots. The proposed antenna operates in three bands (X, Ku and K). The introduced element, has been optimized to achieve large linear phase range at the three bands. Phase compensation is achieved by varying the size of elements. Height of the horn antenna has been optimized to get maximum gain and bandwidth at the three bands. [ABSTRACT FROM AUTHOR]

ABSTRACT A thin, single substrate layered, dual directionally isolated band Meander line antenna (MLA) with connected ends, widened near the feed area, loaded by a U-slot in the patch layer, and by a modification from complementary split ring resonator (CSRR) in the ground layer, is presented for WLAN applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:895-901, 2016 [ABSTRACT FROM AUTHOR]

A novel metamaterial transmission line (TL) by loading complementary single Archimedean spiral resonator pair (CSASRP) is investigated and used to design a set of multi-frequency monopole antennas. The particularity is that the CSASRP which features dual-shunt branches in the equivalent circuit model is directly etched in the signal strip. By smartly controlling the element parameters, three antennas are designed and one of them covering UMTS and Bluetooth bands is fabricated and measured. The antenna exhibits impedance matching better than -10 dB and normal monopolar radiation patterns at working bands of 1.9-2.22 and 2.38-2.5 GHz. Moreover, the loaded element also contributes to the radiation, which is the major advantage of this prescription over previous lumped-element loadings. The proposed antenna is also more compact over previous designs. [ABSTRACT FROM AUTHOR]

In this paper, a novel frequency selective surface (FSS) based on rotationally symmetric bended microstrips is investigated. The unit element consists of twelve L-shaped metal strips and a dielectric substrate. Bended L-shaped strips have different equivalent electric lengths corresponding to different resonant frequencies, which result in multi-band frequency characteristic. Meanwhile, the symmetric metal strips make the FSS polarization insensitive. The numerical experiments demonstrate that the FSS structure has fifteen stop-bands in the frequency band from 6 GHz to 20 GHz, and a good polarization stability as well. Moreover, the FSS design such as the inner radius of L-shaped metal strips, the dimensions of dielectric substrate and the width of the bended metal strips significantly effects on the FSS performance. Because of the multi-band property, the FSS designed in this paper has a bright prospect in many modern wireless communication systems and even in 5G communication system in the future. [ABSTRACT FROM AUTHOR]

A power amplifier (PA) supporting wideband code division multiple access, long-term evolution (LTE), and wireless local area network applications has been implemented in 0.18-\mu\m SiGe BiCMOS technology. The PA integrates a tunable input matching network, a broadband output matching network, and adaptive bias circuits in a single chip to achieve high linearity and high power in different modulation schemes and operating bands. The three-stage PA adopts a differential-type configuration without using through-silicon-via technology to deliver 4 1.3–42 dB of gain and 28.2–28.6 dBm of 1-dB compression output power with a 20.8–27.6% power-added efficiency (PAE) at 1.85–2.5 GHz. To further validate the usefulness of the proposed PA, the envelope-tracking PA is designed to improve the PAE by 6.5% within the linearity specification of a 24.7-dBm average output power and a -33-dBc adjacent channel leakage ratio for 2.35-GHz 16 quadrature-amplitude-modulation time-division LTE signal with 20-MHz bandwidth. [ABSTRACT FROM AUTHOR]

A method in designing multi-band bandpass filter is proposed in this paper. This design employs source and load cross-coupling technique and transversal structure with stub-loaded dual-mode resonators. The proposed filters are miniaturized by using stub-loaded dual-mode resonators, and half of the resonators are reduced compared with traditional SIR filters. What is more, the dual-mode resonators and the source–load cross-coupling can introduce more transmission zeros to improve frequency selectivity. It is demonstrated by the simulated and measured results that the novel filters have the advantages of low in-band insertion loss, good out-band rejection, and compact size. This proposed filter can be applied in the microwave circuits and wireless communication systems. [ABSTRACT FROM AUTHOR]

Design of multi-band Wilkinson power dividers using genetic algorithm are proposed. Based on the ideal transmission line model and the concept of the even-odd modes analysis, the design equations of the multi-band equal-power split WPD with the multi-section transmission line and their corresponding isolation resistances are given. The optimal solutions are obtained via the process of the genetic algorithm optimization. Some numerical examples of the dual-band, tri-band and quad-band Wilkinson power divider are presented to verify the proposed design method. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents the compact penta-band microstrip antenna. The frequency bands of the antenna are WLAN 2.6 GHz (2.56-2.63 GHz), 3.0 GHz (2.94-3.05 GHz), WiMax 3.4 GHz (3.34-3.55 GHz), 4.85 GHz (4.81-4.92 GHz) and WLAN 5.3 GHz (5.27-5.34 GHz). The antenna is rectangular spiral shape and size of the antenna is 20 × 20 mm2. The structures are analysed using Ansoft HFSS v.11 based on Finite Element Method (FEM) and measured results satisfy the simulated results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:836-838, 2016 [ABSTRACT FROM AUTHOR]

Communication between on-chip cores is a challenging issue for high-performance network-on-chip (NoC) design. Wireless NoC (WiNoC) represents an alternative design for planar wired interconnects, aiming to reduce latency and improve bandwidth. In this paper, a novel on-chip fractal antenna is designed and characterized. In order to disseminate interference affecting NoC performance in order to enhance on-chip quality of service (QoS), a set of exclusive sub-channels are assigned to each antenna. The proposed antenna has two wide bands (bi-WB)— B 1 and B 2 , of (63–78) GHz and (101–157) GHz, respectively. The multi-band antenna allows different channel allocations for on-chip core communications. This WiNoC design exhibits improved performance, due to its enhanced antenna bandwidth and the benefit provided by the developed algorithm that can scan and compare to assign the best (upload or download) sub-channels to each antenna. [ABSTRACT FROM AUTHOR]

This paper proposes a four-port, four-element multi-band Multiple-Input Multiple-Output (MIMO) antenna array that resonates at 2.4 GHz, 2.9 GHz, and/or 5.8 GHz frequency bands for WLAN applications. A Complementary Split Ring Resonator (CSRR) was designed on the ground plane of the FR4 substrate with a rectangular patch antenna on the top plane for antenna size miniaturization, bandwidth improvement, compactness, and isolation enhancement. At first, the presence of the CSRR on the conventional antenna creates additional frequency bands and reduces the frequency of the conventional patch antenna from 24.2 GHz to 5.8 GHz. Even though the CSRR as radiating elements are closer to each other at λ/4 in the MIMO design, minimum isolation is achieved by limiting the unnecessary surface current flow that exists between the elements of the antenna. Consequently, an orthogonal method of the antenna element is adopted for the four-port MIMO antenna system with high port-to-port measured isolation of less than −19 dB, −18 dB, and –22 dB for 2.4 GHz, 2.9 GHz, and 5.8 GHz frequency bands respectively. Antenna size reduction of 96.87%, 95.41%, and 81.10% and gain of 3.94 dBi, 3.80 dBi, and 4.08 dBi were achieved for the miniaturized multi-band antenna operating at 2.4 GHz, 2.9 GHz, and 5.8 GHz frequency bands, respectively. The results also provided overall good diversity performances with the ECC < 0.01, DG > 9.98, MEG < 3 dB, and TARC in all of the proposed multi-band MIMO antenna systems at respective frequencies. The reflection & transmission coefficients, surface currents, radiation patterns, total efficiency, and diversity parameters are presented and discussed. Moreover, the proposed integration of CSRR with the antenna for MIMO antenna arrays has the advantage of multi-band operation, size reduction, isolation enhancement, good diversity, and high gain performances. With this, it is possible to conclude that the proposed metamaterial multi-band MIMO antenna is the right candidate for WLAN applications. [ABSTRACT FROM AUTHOR]

This paper presents a simple, compact and low-cost design method that allows one to obtain low-profile multi-band antennas for the overcrowded future generation networks, which are widely versatile and very heterogeneous in the K/Ka bands. The proposed antennas comprise n radiating monopoles, one for each of the desired operating frequencies, along with a frequency selective feeding network fed at a single point. This concept enables a single antenna to be shared with different radio-frequency (RF) frontends, potentially saving space. Typically, with n-band structures the biggest challenge is to make them highly efficient and here this is assured by multiplexing the frequency, and thus isolating each of the monopoles, allowing the design of scalable structures which fit the 5G applications. Based on the vision proposed here, a dual-band and a tri-band structures were built and characterized by their main parameters. Both prototypes achieved peak efficiencies around 80%, with adequate bandwidths and gains, as well as great compactness. [ABSTRACT FROM AUTHOR]

This paper proposes the design of a dual-band integrated rectenna. The rectenna has compact size of 0.4 × 0.3 × 0.25 cm 3 and operates at 925 MHz and 2450 MHz bands. In general, the rectenna consists of two main parts, the metal-rimmed dual-band antenna used for harvesting the radio frequency (RF) signals from the environment and the rectifier circuit to convert these receiving powers to the direct current (DC). Because of the dual resonant structure of the antenna, the rectifier circuit can be optimized in terms of size and the frequency bandwidth, while the conversion efficiencies are always obtained 60% at the RF input power −2.5 dBm and −1 dBm for the lower band and the higher band, respectively. Measured results show that the metal-rimmed antenna exhibits −10 dB reflection coefficient in both desired frequency bands. Moreover, the antenna achieves 47% and 89% of total efficiency respectively at 925 MHz and 2450 MHz, which confirms that the proposed rectenna is well applicable in most of the miniaturized wireless sensor networks and IoT systems. [ABSTRACT FROM AUTHOR]

Over the past decade, IECAS (Institute of Electronics, Chinese Academy of Sciences) has developed a set of L-, S-, C-, and X-band active radar calibrators that are deployed during the calibration campaigns for HJ1C synthetic aperture radar (SAR), Gaofen-3 SAR, and so on. In the near future, P-band and Ka-band spaceborne SARs will be launched. We found that it is not convenient to develop special active radar calibrators (ARCs) for a specific SAR or a specific frequency band SAR, and the acquired experience could help in the design and development of a multi-band ARC. This paper describes the design and implementation of a multi-band active radar calibrator which can operate in the L-, C-, X-, and Ka-bands. Moreover, laboratory measurements are performed to characterize the performance of the multi-band ARC, paying particular attention to the gain stability, the system transfer function, the gain flatness, and the linearity of the ARC receiver. Three such ARCs are developed, and to our knowledge, the multi-band ARC is the first of its kind in China or even in the world, and it can be used to implement the calibration campaigns of the Chinese Gaofen-3 SAR, Shenzhen-1 SAR, Luojia-2 SAR, and so on. [ABSTRACT FROM AUTHOR]