Bandwidth Performance Research Articles

Analysis and Design of a Six-Port Network Based on a Modified Schiffman Phase Shifter

Purpose: This study presents a novel design of a six-port network based on a modified Schiffman phase shifter operating at a 90±2° phase shift. Design/ Methodology/ Approach: The research methodology encompasses a comprehensive literature review, the analysis, design and simulation of the novel phase shifter, its integration into a six-port network, layout design and subsequent post-layout simulation, and comparative analysis to evaluate the new design's performance. Findings: The schematic results showed an operational bandwidth from 5.52 GHz to 12.21 GHz, translating to a fractional bandwidth of 75.47% with a maximum phase error of ±1.8° for the 90° phase shift. Also, the post-layout simulation results from momentum demonstrated outstanding performance with an operation frequency band spanning from 5.52 GHz to 12.21 GHz, representing a factional bandwidth of 75.47% and ±2.1° phase error across the entire band. In addition, good impedance matching was achieved at all the ports well below -10 dB. Practical Implications: It also finds application in satellite communications, where beamforming enhances signal strength and quality by directing the signal towards specific locations on Earth, and antenna arrays for satellite uplink and downlink antennas adjust the beam direction and coverage area dynamically. Social Implications: The social impact of this work includes high-performing communication devices for current and future generations, more accurate measurements, particularly wearable devices in healthcare for monitoring human vitals, weather monitoring systems, high-precision radar systems, wireless gadgets, high-data-rate communication systems, and Internet of Things (IoT) devices. Originality and Value: The study contributes to the existing body of knowledge by introducing an innovative design that addresses the limitations of phase accuracy and bandwidth in Six-Port Networks.

Design of Tri‐Band Doherty Power Amplifier Using Phase and Impedance Constrained Optimization

ABSTRACTTo realize the wideband and efficient operation of Doherty power amplifier (DPA) in multi‐band mode, this paper proposes a tri‐band DPA design method based on phase and impedance‐constrained optimization. First, the phases required for impedance transformation networks across multi‐band are determined based on the impedance required when the DPA operates at back‐off power (BOP) and saturation. Then, the impedance judgment method using multiple impedance constraint circles was employed to determine the optimal load impedances. Finally, the phase and impedance constraints at multiple frequencies were used to optimize the carrier and peaking output matching networks. For verification, a tri‐band DPA operating at 1.25−1.35, 1.9−2.1, and 2.75−2.85 GHz was designed and fabricated. Measured results show that, for the above three frequency bands, the drain efficiencies (DEs) at saturation reach 59.0%−61.7%, 59.5%−64.2%, and 52.4%−59.8% with corresponding output power exceeding 43 dBm. For 6 dB BOP, the DEs are 46.1%−54.2%, 50.4%−55.2%, and 44.8%−51.9%. Moreover, good linearity can be achieved after linearization for 20 MHz modulated signals.

A Four Element UWB MIMO Antenna with Band - Notched Characteristics for Wireless Communication Applications

Abstract: This study proposes an innovative approach to enhance isolation in a four-element Ultra Wide Band (UWB) range Multiple Input Multiple Output (MIMO) antenna system. The design employs unique rhombic and cross-shaped slot structures to achieve compactness, with dimensions of 34 mm × 34 mm × 1.6 mm. To minimize mutual coupling, the antenna incorporates orthogonally placed feed lines alongside a parasitic strip measuring 17 mm × 1 mm × 1.6 mm. The antenna effectively suppresses interference from specific bands, including WiMAX, WLAN, and X-band, through the integration of L-shaped and Cshaped slits combined with Electromagnetic Band Gap (EBG) elements. Simulation results, verified through practical testing, confirm an operational bandwidth 2 GHz to 12 GHz, excluding the targeted notched bands. The design achieves superior isolation (S11 < -10 dB), a peak gain of 2.5–5 dB, and excellent interference rejection capabilities. These features establish the antenna as a highly efficient option for next-generation UWB-MIMO wireless communication applications.

A Cross-Shaped Slotted Patch Sensor Antenna for Ice and Frost Detection

Beyond data transmission, antennas have recently been utilized as sensors, offering the advantage of reducing hardware requirements and power consumption compared to systems where sensors are separate from antennas. Patch antennas, in particular, are widely used across various applications, including sensing, due to their attractive features like compact size and conformability. In addition, they can be easily designed in different ways to sense variations in certain variables. Adding a slot to the patch antenna introduces several advantages, including multiband, wideband operation, and improved impedance bandwidth. Slots also provide a concentrated region of electromagnetic fields, which increases the antenna’s sensitivity for sensing and detection purposes. In this paper, a rectangular patch antenna with a cross slot is designed and proposed for water, ice, and frost detection. Detection is achieved by measuring variations in the resonant frequency in response to water, ice accumulation, and frost. The results indicate that the proposed antenna can detect both water and ice accretion with a frequency shift of up to 1.538, 0.358, and 0.056 GHz, respectively, which reflects good sensitivity levels of the antenna. The effect of the slot on strengthening the near electric field and antenna sensitivity is discussed in this paper. The antenna is fabricated and measured and the indicators of each detection scale have been extracted. The proposed antenna has a simple structure and a small size of (40 × 40 × 1.53 m3). In addition, it can be precisely used to sense different environmental parameters such as frost and ice. Thus, it can serve as a strong candidate for detecting natural disasters like frost damage. Furthermore, the findings in this paper offer valuable insights into how the presence and structure of slots influence the sensitivity response of patch antennas, supporting ongoing research in this field.

Compact wideband tunable phase shifter with minimal in-band phase deviation

ABSTRACT This brief presents a novel design of a compact wideband tunable phase shifter with low in-band phase deviation. Different from the implementation structures of conventional tunable phase shifters, the proposed design is composed of two microstrip lines, two varactor-loaded coupled lines, and an open-circuit stub, which can perform the characteristics of low phase error, large phase shift range, wide operating bandwidth, and compact size simultaneously. Theoretical analysis demonstrates that a relatively large phase shift range and small phase error can be realized by choosing appropriate electrical parameters of the coupled lines and microstrip lines. The measurement results indicate that the fabricated tunable phase shifter operating at 1.9 GHz can provide a maximum continuously tunable phase shift up to 225.5° within the 21.1% fractional bandwidth, with a maximum in-band phase error of ± 3.22°. Meanwhile, the insertion loss is less than 3.95 dB over the operating band.

Broadening the Bandwidth of Epsilon-Near-Zero Metamaterials with Embedded Square Frames

A narrow frequency bandwidth of epsilon-near-zero metamaterials limits the use of many optical, microwave, and electronic devices. In this paper, we propose a recipe to broaden the operational bandwidth by employing a structure of properly tailored square frames nested within each other. To illustrate this effect, we derive the effective permittivity for the considered frame geometry. Then, we show that combining constituent materials with loss and materials with gain enables us to achieve the effective permittivity over a frequency band as small as desired. This technique may prove valuable for various applications including invisibility cloaks, camouflage, shielding, and sensorics.

Utilizing Hertzian contact model for a vibro-impact unimorph bistable energy harvester to increase working frequency bandwidth and harvested power

The typical bistable energy harvester (TBEH) systems usually have a limited working frequency bandwidth and low performance in energy conversion. This paper proposed a unilateral vibro-impact piezoelectric cantilever beam energy harvester. The novel vibro-impact bistable energy harvester (VIBEH) improves the drawbacks of a TBEH system. Despite previous research, in this paper, the collision process is modeled by nonlinear Hertzian contact theory. Nonlinear contact law adds strong nonlinearity to the harvester. By using the extended Hamilton principle and Euler-Lagrange equation, the governing equations of the energy harvester are derived and solved numerically. The existing nonlinearities cause frequency leaks and affect the type of motion (inter-well or intra-well motion) by changing the equilibrium points of the system. By applying nonlinear tools like Poincare diagrams, bifurcation plots, and phase portraits, the effects of periodic or chaotic oscillations will be studied on the performance of the VIBEH system. Finally, the effects of barrier stiffness, initial gap, barrier location, and electrical load are determined on the performance of the VIBEH system. The obtained results showed that using the VIBEH system could broaden the working frequency bandwidth by about 71.9%. Furthermore, the optimized values of impacting properties and electrical load are examined.

Nonlinear metabeam for vibration absorption and energy harvesting

Metamaterials are engineered materials that surpass conventional ones with their exceptional performance. These systems exhibit diverse properties, including excellent energy absorption, acoustic insulation, cloaking, negative Poisson's ratio, and more. In addition, they can possess the remarkable ability to serve multiple functions simultaneously, thereby achieving more than one objective. This study delves into the creation of a beam based on metamaterial engineered to attenuate vibrations while harvesting this kinetic energy for electricity generation. The system works by preventing elastic wave propagation along its length and focusing the incident wave into piezoelectric generators, responsible for the energy conversion. Consequently, we can use this energy to power microelectronic devices such as sensors and actuators. The proposed metabeam consists of a cantilever beam with nonlinear resonators equipped with piezoelectric layers. This arrangement establishes a wide local resonance bandgap on the frequency spectrum of the host beam forbidden the elastic wave propagation. The incident wave is transmitted to the resonators, where they convert kinetic energy into electricity. Nonlinearity is strategically introduced into the resonator to broaden the operational bandwidth. Mathematical modeling is developed, and numerical simulations are conducted to study and demonstrate the performance of the proposed system.

Design, fabrication, and performance analysis of a silicon solar cell integrated transparent antenna for wireless communications

The solar cell integrated transparent antenna will serve the purpose of power generation as well as an antenna for satellites and can act as an asset to expand the possibilities of green technology. The goal is to enhance antenna characteristics without hampering solar cell performance. In this work, a super solar integrated optically transparent microstrip patch antenna has been studied using CST Microwave Studio along with Lumerical FDTD and DEVICE solutions. The optically transparent antenna has a Soda-lime glass substrate, with Indium Tin Oxide patch and ground plane. The fabricated antenna is integrated with a 25 × 40 mm2 thin-film silicon solar cell via epoxy resin. UV–Vis spectroscopy results revealed more than 90% transmissivity over a significant visible wavelength range. It has an operational bandwidth of 80 MHz (@5.48 GHz) and solar simulator results indicate that the photovoltaic performance of the proposed device is similar to that of a standalone solar cell.

Design of Dual Band Bowtie Slot Antenna with Rectangular-Shaped Defected Ground Structure

Abstract The need for 5G antenna has been increasing rapidly due to the development of 5G communication which recently has become popular and advanced. In this research, a bowtie slot antenna with rectangular-shaped defected ground structure (DGS) that can operate at 2.4 GHz and 3.5 GHz, which is used in 5G communication, was designed, simulated and optimized. Parametric study was conducted to study the effect of DGS on the antenna’s performance. The dual band bowtie slot antenna with two rectangular-shaped DGS have been proposed in this paper. The proposed antenna displayed excellent performance in the reflection coefficient of the operating frequency with simulated S 11 around -69 dB and -68 dB at 2.4 GHz and 3.5 GHz respectively. It was observed that multiple rectangular-shaped DGS were able to improve the antenna’s impedance matching, reflection coefficient and bandwidth performance.

A Wideband High Gain Transmit‐Array Antenna Exploiting Polarization‐Rotated Metasurface Cell

ABSTRACTA novel polarization‐insensitive transmit‐array (TA) antenna using linear polarization‐rotated (PR) metasurface (MS) unit cells has been proposed in this article. Firstly, we design a wideband polarization‐insensitive polarization‐rotated MS unit cell. The MS cell can provide high transmission for incident linear polarized waves with polarization rotation by 90°. Then, we investigate the stability of the MS cell under the oblique incident wave. The proposed MS cell keeps a stable response under oblique incident wave over ± 30°. To verify the excellent performance of the proposed MS. We design a high‐gain TA antenna consisting of a standard feed horn and an aperture with a gradient phase. The gradient phase compensation is provided by varying the geometric dimension of the proposed MS. The obtained TA antenna works in a wide band with high gain. We fabricated the aperture and set up a prototype of TA antenna to verify our work. We measure the TA antenna and the results show a wide operating band from 14.2 to 18 GHz with a pick gain of 23.9 dBi. The favorable performance of the TA antenna is a good candidate in satellite systems and long‐distance satellite system. Furthermore, the angular stability of the MS cell is also verified by realizing the beam scanning performance. An over ± 30° scan range is obtained. Good beam scanning can be used in radar detection and expand signal coverage.

Symmetrical In‐Band Full‐Duplex Antenna With Broad Bandwidth Using Stacked Patch Array

ABSTRACTThis article proposes a novel symmetrical design for a Broadband Bidirectional In‐band Full‐duplex (IBFD) co‐radiator antenna with high isolation. The distinctive double differential feed network, constructed using orthogonally arranged meander slot baluns, is connected to a pair of co‐radiating patches with the metallic visa, resulting in structural symmetry and offering bidirectional radiation patterns. The null‐coupling features of the balun, that is, the differential potentials and differential filtering, generate good isolation in the antenna with a narrow bandwidth. The limitation of narrow bandwidth has been overcome by employing a stacked patch array above the radiating patch. The installed stacked patch array generates additional resonating modes due to the induced surface waves and enhances the operational bandwidth of the antenna. The multiple techniques of polarization diversity, double differential feed, and stacked patch array in the antenna offer a minimum isolation of 62 dB over a wide operational band of (1.8–2.9) GHz. It offers bidirectional broadside radiation having a lower cross‐polar of dB. Moreover, the structural symmetry of the antenna produces identical S‐parameters, gain, and radiation patterns for both antenna ports. The fabricated prototype of the proposed antenna with overall dimensions of ( is the free space wavelength referring to the lowest operational frequency) shows a good correlation between the simulated and measured results.

Portable real-time polarimeter for partially and fully polarized light.

We present a portable polarimeter capable of real-time visualization of partial and fully polarized light over a broad band of wavelengths. Our system utilizes a Raspberry Pi computer with a low-cost data acquisition "HAT" and an integrated photodetection circuit. Wide bandwidth operation is achieved through digital calibration of an arbitrary retardance waveplate presented herein. All mechanical, electrical, and software components are open source and available on a GitHub repository. This completely integrated approach provides an efficient tool for modern optics research laboratories and is well-suited for educational demonstrations.

Fully Metallic Additively Manufactured Monopulse Horn Array Antenna in Ka-Band

The Laser Powder-Bed Fusion Additive Manufacturing (LPBF AM) technique is evaluated for the manufacturing of fully metallic monolithic microwave components. To validate the manufacturing technique, a difference pattern array of 4 × 4 horn antennas is designed to operate at mm-Wave frequencies. The antenna is based on H-plane power dividers and a complex structure to obtain a difference radiation pattern by rotating twisted sections in two different orientations. The prototype is manufactured with a monolithic piece of aluminum alloy AlSi10Mg, providing a lightweight single structure that includes both radiating elements and a feeding network consisting of twisters and power dividers in a waveguide. The prototype was experimentally evaluated in an anechoic chamber and the near-field planar acquisition range, obtaining good agreement with full-wave simulations within an operational bandwidth from 34 to 36 GHz. The results demonstrate that the LPBF AM technique is a suitable candidate to produce challenging monolithic metal-only microwave components in the Ka-band, such as monopulse antennas.

Persistent photoconductivity and Emulating Ebbinghaus forgetting curve via characterization of excitatory synaptic transmission in a ZnO-based optoelectronic synapse with ultra-low power ([formula omitted] fJ) consumption

Optical synapses provide high bandwidth operation with low power consumption for neuromorphic computing. ZnO is established as a potential semiconductor for optoelectronic synapses with its high photosensitivity in the ultraviolet (UV) region. In this work, we focus on emulating Ebbinghaus forgetting curves via conductance decay and memory retention in a lateral synaptic device based on ZnO nanoparticles. We use optical stimulation using UV light of wavelength 375 nm. Retention of memory can be seen up to 2500 s showing long-term potentiation which is useful for memory and learning abilities. Long-duration memory retention using optical spiking is achieved and the decay characteristics of the memory are studied. A transition from short-term plasticity (STP) to long-term plasticity (LTP) can be induced by tuning the optical pulse width. Energy consumption is found to increase exponentially with the applied optical pulse width. The conductance decay follows the Ebbinghaus forgetting curve. We have demonstrated the effect of various measurement parameters such as pulse width, pulse frequency, and pulse amplitude on memory decay. The synaptic device can be operated with energy consumption as low as 1.2 fJ which paves the way for very low energy-consuming synaptic devices for neuromorphic applications.

MATHEMATICAL MODELING OF SECURE MULTIPOINT VIDEO CONFERENCE SESSIONS USING MULTILAYER GRAPHS

The article describes a multilayer graph model for multipoint videoconference sessions. The model presented in this study allows to specify requirements for quality of video capture quality when transferred between terminals and multipoint control unit at the service layer, as well as assessing bandwidth performance and delay of datalink channels at the secure and transport network layer. The given multilayer graph model for videoconference system is designed taking into account the features of secure network configuration, in which several overlay network layers are distinguished over transportation networks. This model specifies a structure of multipoint videoconference session at service layer, at which videoconferencing terminals interoperate through server. Traffic flows generated during session are distributed according to routing rules at the secure network layer. A purpose to select the most optimal route configuration for the entire session includes a number of alternative methods to distribute traffic for each pair of client-server communication seems to be rather complicated. The study proposes an algorithm for searching the shortest path in the graph of a secure overlay network with a step-by-step projection fer each individual route section onto the underlying level of the transport network to find the shortest path within its boundaries. An example for solving a problem on finding route in regard to the overlay network requirements and the actual traffic flow through the transportation network is given. Minimization of the capacity usage of leased channels was chosen as the optimality criterion. Experiments were conducted to evaluate the session quality based on the objective methods for various video-stream parameters, and corresponding quantitative estimates of the required bandwidth in order to organize a session.

Compact and ultra-wideband high-efficiency rectifier using asymmetric coupled-line impedance transformer

Abstract This paper presents a compact and ultra-wideband high-efficiency microwave rectifier for wireless power transmission (WPT) applications. The input-matching-network utilizes a compact asymmetric coupled transmission line structure, contributing to wideband performance. The rectifier adopts a voltage-doubler topology, resulting in a smooth input impedance across a wide bandwidth. The working principle of the asymmetric coupled transmission line matching network is analyzed. Simulation and measurement are conducted on the proposed rectifier. The fabricated prototype demonstrates a wide bandwidth of 162.5% (0.3–2.9 GHz with the power conversion efficiency (PCE) exceeding 60% at an input power of 18 dBm. Even at an input power of 10 dBm, the measured PCE remains above 50% over the working band. The proposed ultra-wideband rectifier shows promising potential for WPT applications including wireless powering of low-power electronic devices and sensors.

Wideband star-shaped antenna based on artificial magnetic conductor surface for unidirectional radiation

Gathering the advantages of low profile, high gain, high efficiency, and wideband operation in a planar antenna is a challenging objective for the antenna designer. Low profile wideband antennas are usually characterized by low gain. An antenna of wideband impedance matching usually suffers continuous variations of the gain over such a wideband due to the variation of the radiation mechanisms and surface current distributions over the frequency band of impedance matching. Therefore, the motivation of the present work is to provide both impedance matching and stabilized high gain by the aid of wideband artificial magnetic conductor (AMC) with a design of the unit cell that is suitable to the antenna structure and the desired frequency band. The present work, proposes the utilization of low-size wideband AMS surface (AMCS) to be placed behind a wideband omnidirectional antenna to enhance the gain over the frequency band of operation. In this way, the radiating structure combines high gain and wideband operation in the same design. A wideband planar monopole printed antenna is designed to operate as omnidirectional antenna with perfect impedance matching and radiation efficiency over the frequency band 3.6-7.2GHz when placed in free space. The gain of the free-standing antenna varies from 2dBi to 4.5dBi over the frequency band. A wideband AMCS is designed to enhance the antenna gain over frequency band of operation. The designed AMCS is composed of only 3×3 unit cells and overall dimensions of 10×10cm. This surface is placed parallel to the planar antenna at a distance 1.7cm behind it. The enhanced gain of the radiating structure of the AMCS-backed antenna reaches 8.5dBi without affecting the bandwidth over which the input impedance is matched to the feeding line. The radiation efficiency of the AMCS-backed antenna is maintained above 98% over the frequency band of operation (3.7-7.2GHz). The wideband antenna and the AMCS are fabricated for practical evaluation of the overall AMCS-backed antenna performance including the measurements of impedance matching, gain and radiation efficiency. The measurements and simulation results are in good consent.

Design and modeling of three-mode nonlinear hybrid piezoelectric-electromagnetic vibration energy harvester for harvesting multi-band vibration energy on the freight wagon axle box

Abstract With the rapid development of rail transit system, it is becoming more demanding for structural health monitoring (SHM) of the train. It is crucial to supply power for sensing devices on the freight wagon to ensure the safe operation of rail transit systems. Three-mode nonlinear hybrid piezoelectric-electromagnetic vibration energy harvester (TNHVEH) with a three-layer pickup system has been designed and applied to efficiently harvest vibration energy on the axle box of freight wagons for providing the power of the sensors for online SHM. Dynamic coupling model of the vehicle-harvester system is built to devote the relationship between the operation bandwidth and the nonlinear degree of TNHVEH for broadening the operation frequency band. Simulation and experimental results demonstrate that the resonant frequencies of the three pickup systems of TNHVEH are concentrated around 27, 70, and 120 Hz, matching the representative frequencies of axle box vibrations. A maximum output voltage of 2.97 V and output power of 29.4 μW under an optimal load of 300 kΩ at 0.5 g acceleration is achieved. It successfully lights up 53 LEDs with ‘ECJTU’ patterns, providing a solution to the power supply problem of microelectronic devices on freight wagons.

Design of band reconfigurable Koch fractal antenna for wideband applications

In this communication, a band reconfigurable fractal antenna with modified partial ground is proposed for wireless applications. Four switches using PIN diodes supported by the antenna biasing circuit provide frequency reconfigurability, while star-shaped fractal geometry is used to achieve both miniaturisation and wideband functioning in the proposed antenna. The surface current distribution of the radiating patch is altered by the ON and OFF states of the PIN diode, which leads to the multiband resonance and reconfiguration features of the designed structure. The designhas an overall electrical size of 70 × 45 × 1.6 mm3 and is made on a commonly available FR4 substrate with a thickness of 1.6 mm and a dielectric constant of 4.4. The three operational bands are as follows: case I, which covers 3.7–5 GHz (30 %); case II, which covers 1.7–3.5 GHz (71 %); and case III, which covers 1.4–4 GHz (96 %). Two distinct bands are obtained in cases I and II; and case III nearly covers the frequency band of cases I and II. Therefore, the impedance bandwidth (IBW)offers continuous wideband frequency coverage from 1.4 to 5 GHz (110 %). To sense the full band and then modify its bandwidth to choose the appropriate sub-band and prefilter out the others, the proposed antenna may switch between a wide operational band of 1.4–5 GHz with three distinct subbands. The antenna could potentially be useful for wireless communication systemsin the future due to its frequency-selective feature and stable radiation patterns.