Bandwidth Characteristics Research Articles

The Single-Pitch Texel: A flexible and practical texture-rendering algorithm.

As the number of applications for tactile feedback technology rapidly increases, so too does the need for efficient, flexible, and extensible representations of virtual textures. The previously introduced Single-Pitch Texel rendering algorithm offers designers the ability to produce textures with perceptually wide-band spectral characteristics while requiring very few input parameters. This paper expands on the capabilities of the rendering algorithm. Diverse families of fine textures, with widely varied spectral characteristics, were shown to be rendered reliably using the Texel algorithm. Furthermore, by leveraging an assistive algorithm, subjects were shown to consistently navigate the Texel parameter space in a matching task. Finally, a psychophysical study was conducted to demonstrate the rendering algorithm's resilience to spectral quantization, further reducing the data required to represent a virtual texture.

3D-printed stepped structure based on graphene-FeSiAl composites for broadband and wide-angle electromagnetic wave absorption

The design and preparation of absorbers with ultra-wide bandwidth and wide-angle absorption characteristics are crucial technologies for addressing electromagnetic (EM) pollution. In this paper, a stepped structure absorber was fabricated of graphene (GR)-FeSiAl/polylactic acid (PLA) composite by 3D printing technology. The absorber contains four layers, the bottom layer being a slab with periodic square holes, and the upper layer is a periodic distribution of three cubes with equal thickness and gradient changes in side length. It is shown that the stepped structure achieves a minimum reflection loss (RLmin) of −36.01 dB, with an effective absorption bandwidth (EAB, corresponding to the bandwidth of RL < −10 dB) of 12.75 GHz. These results were obtained when the unit cell had a side length of 22.5 mm, the slab thickness was 1.5 mm, and the cube had a thickness and edge length difference of 2.5 mm and 4.0 mm, respectively. Furthermore, the value of EAB is greater than 10 GHz for both transverse electric (TE) polarization and transverse magnetic (TM) polarization when the incident angle changes from 0° to 50°. The broadband and efficient EM wave (EMW) absorption characteristics of this absorber can be attributed to integration of excellent impedance matching and the multi-scale loss mechanisms.

Design and verification of a tunable single-band metamaterial based on Polymeric Methyl Methacrylate and its feasibility for temperature detection in smart packaging

Metamaterial absorbers with single resonance mode and narrow bandwidth are often used in sensing. A metamaterial absorber containing dielectric layers of the same thickness (Polymeric Methyl Methacrylate (PMMA) and strontium titanate (STO)) are proposed and confirmed. At room temperature (300 K), an individual absorption peak is excited, and the single resonance mode and narrow bandwidth characteristic are obtained. The amplitude and resonance frequency of the metamaterial samples can be controlled by changing the thickness of PMMA or STO. The metamaterial samples are placed in an environment with a gradual change in temperature. The results show that the absorptive properties of the metamaterial sample show remarkable repeatability in the process of temperature increase and decrease. Therefore, based on the properties of single resonance mode, narrow bandwidth, and reversibility, the metamaterial samples have the potential to be used in smart packaging sensing.

Cost-Effective Design of Polarization and Bandwidth Reconfigurable Millimeter-Wave Loop Antenna.

A singly fed reconfigurable circular loop antenna is proposed for millimeter-wave (mmWave) communication systems. This antenna's distinctive feature lies in its capacity to adjust both polarization and bandwidth characteristics, a capability made possible by the strategic integration of two PIN diodes. These diodes are engineered to function in various modes, allowing for three distinct polarization states and accommodating two distinct bandwidths. A meticulous alignment of these PIN diodes enables the utilization of a single DC bias network as a highly effective RF choke, which simplifies the design and reduces the associated losses. Additionally, a planar biasing network that consists of coplanar strip-lines (CPS) has been employed eliminating the need for lumped elements. The simple and totally planar configuration offers a choice of right-hand circularly polarized (RHCP) radiation or left-hand circularly polarized (LHCP) radiation at 28 GHz. This is accompanied by impedance matching and axial ratio (AR) bandwidths of 12.9% and 8%, respectively, over the same frequency range with a gain of 7.5 dBic. Moreover, when the PIN diodes are unbiased, the antenna offers linear polarization (LP) over two narrow bandwidths at 27 GHz and 29 GHz featuring a maximum gain of 7.2 dBic. Therefore, the proposed configuration offers three operating modes: wide-band RHCP, wide-band-LHCP, and LP over dual narrow bands. Significantly, simulated results closely align with the measured outcomes, affirming the robustness and accuracy of this design.

Study on Broadband Dynamic Characteristics of Photovoltaic DC Arc

The low current and wideband characteristics of photovoltaic (PV) DC arc make it difficult for traditional protection devices to detect it effectively. Therefore, it is important to analyze the wide-band dynamic characteristics of PV DC arc and extract the fault features. In this paper, firstly, the fault simulation of the engineering PV DC arc with a compound arc model is performed in PSACD. Then the simulation of various interference conditions and the fault conditions are carried out. Taking the output current of the combiner box as the object, the randomness of the signal is described by the pulse factor, and the characteristics of arc fault are reflected from the time domain. Then the fault characteristic frequency band is obtained based on the band energy ratio and information entropy ratio and the characteristic of arc fault is reflected by the energy and information entropy. The results show that the proposed broadband dynamic characteristic analysis method can effectively reflect the DC arc fault.

A Low-Profile Quad Element High Isolation MIMO Antenna for Enhanced Mobile Broadband Applications

A novel quad-element bio-inspired virus-shaped Multiple Input-Multiple Output (MIMO) antenna with significantly improved isolation is proposed. Each radiator is based on a modified hybrid fractal antenna with a 50 Ω feed and incorporates a chamfered defective ground structure (DGS). To enhance the impedance bandwidth and radiation characteristics of the antenna, an elliptical slot and the DGS are employed. The placement of radiating elements in an orthogonal configuration is a key aspect of achieving the proposed MIMO configuration. In many MIMO designs, one of the primary challenges is achieving adequate isolation between antenna ports. However, in this design, we address this issue effectively by incorporating a swastik-shaped decoupling plane, which significantly enhances the isolation characteristics. The 4-port MIMO antenna is constructed on a Rogers RO3003 substrate and boasts compact dimensions of 57 × 57 × 0.787 mm³. The fabricated antenna has undergone experimental validation, confirming that it covers a substantial operational bandwidth of 41.57 GHz, ranging from 2.54 to 44.1 GHz, has a fractional bandwidth of 178%, and maintains isolation levels of less than −23 dB across its entire frequency range. The antenna design has achieved optimal MIMO performance, characterized by an Envelope Correlation Coefficient (ECC) value of ≤0.05, high multiplexing efficiency, minimal Channel Capacity Loss (CCL), and omnidirectional radiation properties. Hence, this design stands as an epitome for constructing super-wideband MIMO designs. The design metrics show the potential of the proposed antenna to operate with Enhanced Mobile Broadband (eMBB) which forms an integral part of 5G applications.

Design process of a compact Tri-Band MIMO antenna with wideband characteristics for sub-6 GHz, Ku-band, and Millimeter-Wave applications

This article proposes a tri–band Multiple Input Multiple Output (MIMO) antenna operating at 5.2 – 5.7 GHz (5G Wi–Fi), 11.8 GHz – 17.3 GHz (Ku–band), and 23.4 GHz – 37.3 GHz (5G millimeter–Wave) frequency bands. The proposed MIMO antenna consists of a 2 × 2 configuration with a defective ground structure on Rogers–5880 substrate. An innovative passive decoupling structure, featuring thin microstrip lines positioned between the radiating elements, has been meticulously engineered to ensure a high level of isolation, achieving values of less than −20 dB. The peak gain of the MIMO antenna is found to be 3.05 dB, 5.27 dB, and 6.97 dB at 5.5 GHz, 17 GHz, and 35.5 GHz frequency bands, respectively. Measured ECC is less than 0.007, and DG is greater than 9.96. The radiation efficiency is above 90 %, TARC is less than –10 dB and channel capacity loss is below 0.4 Bits/s/Hz in all the bands of operation. The simulated and measured results are found to be in good agreement and the proposed MIMO antenna offers numerous advantages, including extensive frequency coverage, broad bandwidth, exceptional isolation, high gain, and efficiency. Consequently, it emerges as a promising choice for devices operating in Sub-6 GHz, Ku-band, and millimeter-wave applications.

Comparative performance and injection characteristic of air source heat pump with conventional and active refrigerant injection

An active sub-cooler refrigerant injection (ASCRI) based on low-grade heat source was proposed. This injection method can convert the external heat source into heating capacity (Qh) in the form of refrigerant injection enthalpy difference, thus greatly increasing the Qh and solving the problem that the heat pump with conventional refrigerant injection (CSCRI) cannot be applied in extremely cold areas. The thermodynamic model has been built to calculate the heat pump performance (HPP) parameters and determine the influence factors. The HPP and injection characteristic of CSCRI and ASCRI were comparatively tested. Experimental results show that effects of ASCRI on improving the performance were better than those of the CSCRI. At low ambient temperature, the maximum Qh/coefficient of performance (COP) of the heat pump with CSCRI and ASCRI were 6611 W/2.33 and 7730 W/2.49, 17.8 %/11.5 % and 37.7 %/19.1 % higher than those of the none-injection heat pump, respectively. The bandwidth characteristic of the ASCRI was superior to that of the CSCRI. For the Qh/COP, the effective bandwidth scopes of the sub-cooling electronic expansion valve with CSCRI and ASCRI account for 8 %/2 % and 75 %/60 % of total opening range, respectively.

Design and Performance Evaluation of a Second-Order Iterated Circular Minkowski Fractal Antenna for Ultra-Wideband Applications

In this article, a second-order iterated Circular Minkowski fractal antenna (CMFA) tailored for ultra-wideband (UWB) applications is designed and developed. Leveraging the power of Minkowski fractal geometry, this antenna design achieves a high gain across the UWB frequency spectrum. The design utilizes a circular groove on the ground plane and an arc slot on the radiating element for improving the antenna performance. The proposed antenna is fabricated using cost-effective material, an FR-4 substrate. The antenna is simulated and optimized. The fabricated optimized antenna undergoes real-world testing. Measured results reveal an impressive 120.6% impedance bandwidth spanning from 3.37 GHz to 13.6 GHz, with resonant frequencies at 4.43 GHz, 6.07 GHz, and 9.3 GHz. Meanwhile, the simulated results indicate an impedance bandwidth of 118% ranging from 3.17 GHz to 12.44 GHz. Real-world measurements validate the anticipated UWB traits, closely aligning with the simulation data, and confirming efficient impedance matching with a VSWR of less than 2 across the 3.37 GHz to 13.6 GHz frequency range. The radiation pattern analysis demonstrates a robust bidirectional E-plane pattern and a nearly omnidirectional H-plane pattern. This research introduces a highly promising circular Minkowski fractal antenna for UWB applications, offering exceptional bandwidth and resonance characteristics. This antenna design holds excellent potential for multi-functional wireless systems and opens avenues for enhanced UWB communication and sensing capabilities in diverse applications.

GNSS/UWB/INS indoor and outdoor seamless positioning algorithm based on federal filtering

An integrated navigation system plays an important role in the application of indoor and outdoor seamless positioning. Essentially, it is a flexible fusion positioning of multiple sensors with different combinations. The Global Navigation Satellite System (GNSS) can provide high-precision positioning and navigation in an outdoor environment with good observation conditions. Ultra-wide Band (UWB) has the characteristics of great bandwidth and anti-multipath, which can be applied to provide high-precision positioning and navigation indoors. Inertial Navigation System (INS) has independent navigation capabilities that can be tightly combined with GNSS and UWB to enhance positioning robustness. In response to the problem of a single sensor struggling to provide reliable location information for indoor and outdoor seamless positioning, this study applies federal filtering to integrate and construct the GNSS/UWB/INS integrated positioning algorithm based on Horizontal Dilation of Precision (HDOP) of UWB and carrier-to-noise ratio of GNSS weighting. The gross errors are first detected during the data preprocess, and an adaptive weighting approach to reduce the influence of the anomalous observations is constructed. The tight combination of GNSS/INS and UWB/INS is implemented in the subfilter of the federal filtering. In the main filter, the weights of the two subfilters are adjusted based on HDOP and carrier-to-noise ratio weighting, and the information is allocated and fused to reduce the impact of potential poor UWB geometric configuration on the positioning solutions. It is proven that the error in the horizontal direction in the indoor and outdoor seam area is less than 10 cm. Compared with conventional federal filtering and Huber-based Kalman filtering, the algorithm in this study improves the accuracy of the reference point in indoor and outdoor seam area by 46.1% and 15.4%, respectively, which is beneficial for applications in indoor and outdoor seamless activities.

Quad Element MIMO Antenna for C, X, Ku, and Ka-Band Applications.

This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3-15.5 GHz, encompassing the C band (4-8 GHz), X band (8-12.4 GHz), and a significant portion of the Ku band (12.4-15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4-34.3 GHz and 36.1-48.9 GHz, which corresponds to 86% of the Ka-band (27-40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, -6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It's worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna's ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3-5 GHz); WLAN (4.9-5.725 GHz); Wi-Fi (5.15-5.85 GHz); LTE5537.5 (5.15-5.925 GHz); WiMAX (5.25-5.85 GHz); WLAN (5.725-5.875 GHz); long-distance radio telecommunication (4-8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8-12 GHz; X-band); and various satellite communications (27-40 GHz; Ka-band).

Direction of Arrival Estimation and Highlighting Characteristics of Testing Wideband Echoes from Multiple Autonomous Underwater Vehicles.

Multiple autonomous underwater vehicles (AUVs) have gradually become the trend in underwater operations. Identifying and detecting these new underwater multi-targets is difficult when studying underwater moving targets. A 28-element transducer is used to test the echo of multiple AUVs with different layouts in a lake. The characteristics of the wideband echo signals are studied. Under the condition that the direction of arrival (DOA) is not known, an autofocus coherent signal subspace (ACCSM) method is proposed. The focusing matrix is constructed based on the received data. The spatial spectrum of the array signal of multiple AUVs at different attitudes is calculated. The algorithm estimates the DOA of the echo signals to overcome the shortcomings of traditional wideband DOA estimation and improve its accuracy. The results show that the highlights are not only related to the number of AUVs, but are also modified by scale and attitude. The contribution of the microstructure of the target in the overall echo cannot be ignored. Different parts of the target affect the number of highlights, thus resulting in varying numbers of highlights at different attitude angle intervals. The results have significant implications for underwater multi-target recognition.

Dual port asymmetrical dumbbell-shaped dielectric resonator-based MIMO antenna with pattern diversity for wideband applications

ABSTRACTIn this article, a wideband ceramic-based dual port MIMO (Multi Input Multi Output) antenna is investigated and analyzed. Wideband features are obtained with the assistance of asymmetrical dumbbell-shaped cylindrical ceramic. Triple-band circular polarized waves are also obtained with an S-shaped aperture having unequal strip length. Other special characteristic of the proposed MIMO radiator is to achieve bidirectional pattern diversity by placing radiators in opposite direction. Measured outcomes confirm that the proposed radiator offers a fractional bandwidth of 65.04% (4.02 to 7.89 GHz) with less than −25 dB mutual coupling between two identical ports. In between the three frequencies range, i.e., 4.75 to 5.02 GHz, 5.75 to 6.2 GHz, and 7.55 to 7.82 GHz, the value of axial ratio is well below the value of 3 dB. Measured far-field pattern and diversity parameters authorize the appropriateness of the proposed radiator in MIMO system.

A low-profile flower-shaped MIMO antenna for wireless applications

ABSTRACT A low-profile, compact and efficient antenna is especially desirable for wireless applications, as it can reduce the size and weight of the system and improve its performance. In recent years, flower-shaped antennas have gained popularity due to their low profile, broad bandwidth and good radiation characteristics. In this work, a high-isolated dual-element UWB-MIMO antenna is experimentally verified having size of 32 × 39 × 0.8 mm3. The main radiating element of MIMO setup comprises a Half-Cut Flower-Shaped (HCFS) resonator. A tree-shaped decoupling structure is use to enhance the isolation. The simulated operating band of the proposed 2-port UWB-MIMO antenna ranges from 2.3 to 2.68 GHz and 3.15 to 12.87 GHz which covers Bluetooth, Wi-Fi/WLAN, Wi-MAX and UWB) with inter-element isolation of more than 15 dB and 20 dB, respectively. The measured results are found in close agreement with simulated ones. Furthermore, the diversity parameters such as Envelope Correlation Coefficient (ECC), Channel Capacity Loss (CCL), Mean Effective Gain (MEG), Effective Diversity Gain (EDG) and Total Active Reflection Coefficient (TARC) have also been analysed to ensure its legitimacy for wireless applications. Moreover, the simulation S-parameters characteristic of the proposed 8-element antenna for wireless access point applications has also been showcased.

SiAlON composite films with strengthened chemical intermixing for wide infrared absorption band

Broadband infrared absorbers have been intensively developed in recent decades due to their wide range of applications. Current infrared absorbers usually adapt complicated photonic designs to meet increasing demands, since natural infrared material (e.g., dielectrics, polymers, and metals) can hardly realize broadband and spectrally selective absorption simultaneously. In this paper, a novel infrared absorbing composite SiAlON is proposed and successfully fabricated by co-sputtering Si3N4 and AlN. Its wide-band absorption characteristics across through 8 to 16 μm can be tuned simply via adjusting its deposition conditions. The corresponding optical and composition analyses confirm that the broadband features with spectral selectivity are attributed to chemical composition control and the chemical bonding state tunability. This work extends the bandwidth and improves the absorbing flexibility of single material, making a step forward to develop broadband infrared absorbers with simpler structure.

Design of a Dual-Band Dielectric Resonator Antenna Array for Millimeter-Wave Communication

This paper presents a dual-band dielectric resonator antenna (DRA) with a large frequency ratio at millimeter-wave band. A large frequency ratio of 2.36 is formed by the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> mode and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">131</sub> mode working at 16 GHz and 38 GHz, respectively. These two modes of DRA are excited by a microstrip-fed slot. A 1×4 DRA array is then constructed to achieve high gain in the millimeter-wave range. In addition, this design also features easy fabrication and wideband characteristics achieved through the use of printing circuit board (PCB) technology. The impedance bandwidths of 13.3 – 19 GHz (35.3%) and 36.3 – 40 GHz (9.7%), and the gain of 10.6 and 14.2 dBi can be realized in these two bands, respectively. The good agreement between measurement and simulation suggests that this design has promising potential for application in millimeter-wave communication.

3.5 GHZ VIVALDI ANTENNAS: A COMPREHENSIVE PARAMETRIC ANALYSIS FOR UNLEASHING 5G COMMUNICATION TECHNOLOGY

In this study, we discuss the design and testing of a Vivaldi antenna operating at 3.5 GHz, which is well-suited for mobile mid-band 5G connection. CST Microwave Studio software was used to simulate and evaluate the suggested antenna design, which was printed utilising state-of-the-art 3D printing processes and materials (polylactic acid (PLA) and FR-4 circuit board material). The measured results show that the antenna has a reflection frequency of 3.51 GHz and a gain of -23.695 dB. Parametric analysis was carried out to examine the relationship between antenna performance and design parameters, with special focus on the separation between the antenna and the PLA material in the middle of the spherical construction. The Vivaldi antenna is an attractive choice for 5G mid-band applications because of its wideband features, ease of manufacture using typical industrial processes, and simplicity of impedance matching to the feeding line using microstrip line modelling.

Nature-inspired spider web shaped UHF RFID reader antenna for IoT and healthcare applications

This paper proposes a nature-inspired spider web-shaped ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna and battery-free sensor-based system for healthcare applications. This antenna design consists of eight concentric decagons of various sizes and five straight microstrip lines.These lines are connected to the ground using 50 Omega resistors from both ends, except for one microstrip line that is reserved for connecting a feeding port. The reader antenna design features fairly strong and uniform electric and magnetic field characteristics. It also exhibits wideband characteristics, covering whole UHF RFID band (860–960 MHz) and providing a tag reading volume of 200 times 200 times 20 mm{^3}. Additionally, it has low gain characteristics, which are necessary for the majority of nearfield applications to prevent the misreading of other tags. Moreover, the current distribution in this design is symmetric throughout the structure, effectively resolving orientation sensitivity issues commonly encountered in low-cost linearly polarized tag antennas. The measurement results show that the reader antenna can read medicine pills tagged using low-cost passive/battery-free RFID tags, tagged expensive jewelry, intervenes solution, and blood bags positioned in various orientations. As a result, the proposed reader antenna-based system is a strong contender for near-field RFID, healthcare, and IoT applications.

Circularly polarized MIMO patch antenna with high isolation and wideband characteristics for WLAN applications

This paper presents a two-element multiple-input multiple-output (MIMO) antenna with circular polarization diversity. The primary radiating elements are two conventional truncated corner microstrip patches. To enhance the antenna's bandwidth, gain, and port isolation, multiple parasitic elements are employed and they are positioned in different layer with the radiating patches. For further isolation improvement, a method of using defected ground structure is employed. The measured results demonstrate that the proposed antenna possesses wideband operation of 9.3% (5.1–5.6 GHz) with the gain of better than 8.0 dBi. Regarding the MIMO performances, the antenna obtains high isolation, which is from 30 to 63 dB. Besides, the MIMO parameters such as envelope correlation coefficient and diversity gain are found to be good in the scale of diversity standards. Compared to other related works, the proposed design has the best operating BW with 40-dB isolation and stable gain while keeping small element spacing.

Design of a compact sigma slotted dual-mode UWB antenna for wireless body area network applications

Abstract This article presents the design of a novel sigma slotted circular monopole antenna for wireless body area network applications. The design is proceeded with a sigma-shaped slot etched on the circular radiator with Rogers 4003C substrate. The size of the proposed antenna is 30 × 30 × 1 mm3. With partial ground plane, the bandwidth characteristics of the antenna have been enhanced. The designed antenna covers 2–10 GHz of the ultra wideband, thereby providing more than 106% bandwidth. The antenna exhibits high gain values of 1.95, 3.23, 3.46, and 5.95 dB at 2.45, 3.45, 5.8, and 9.5 GHz, respectively. The proposed design operates on off-body mode at 2.45 GHz and on-body mode at 5.8 GHz, thus acting as a dual-mode antenna. To ensure the health and safety measure, specific absorption rate analysis was done for both low and high values of input power and also with Cartesian and cylindrical human arm models. Bending analysis was also done. The time domain parameter group delay was also analyzed for the proposed antenna for on- and off-body scenarios. The prototype was fabricated, and validation of simulation results was done for free space and on-body scenarios.