PIER B | PIER Journals

2024-08-25

PIER B

Vol. 107, 139-153, 2024

download: 53

Negative Group Delay Prototype Filter Based on the Ratio of Two Classical Chebyshev Filter Transfer Functions

Miodrag Kandic and Greg E. Bridges

A Negative Group Delay (NGD) prototype filter design, based on the ratio of two Chebyshev filter transfer functions, is presented. The two transfer functions are of the same order, but with different in-band ripple amplitudes and different 3 dB-bandwidths. The overall transfer function exhibits both an in-band ripple and an out-of-band steep-slope magnitude transition characteristic of a Chebyshev filter, while also exhibiting an in-band NGD. For high-order designs and in the upper asymptotic limit, the NGD-bandwidth product of the filter is shown to be a linear function of out-of-band gain in decibels. A resonator-based methodology is used to show how frequency upshifted filter designs can be implemented in a Sallen-Key topology or in an all-passive ladder topology. An in-band combined magnitude/phase distortion metric is evaluated for examples of the NGD filter. It is shown that the distortion metric is proportional to the design order, the in-band ripple amplitude, and the out-of-band gain. For a prescribed distortion metric value, it is demonstrated that the proposed design can achieve a higher NGD-bandwidth product than an equivalent Butterworth design, which has a flat in-band magnitude characteristic. Additionally, input waveforms with bandwidths extending to the entire frequency range where the group delay is negative (typically larger than the 3dB-bandwidth) should not be applied to this filter design as it results in strong levels of distortion.

Negative Group Delay Prototype Filter Based on the Ratio of Two Classical Chebyshev Filter Transfer Functions

2024-08-12

PIER B

Vol. 107, 125-137, 2024

doi:10.2528/PIERB24051303

download: 169

An Eight-Element MIMO Antenna System Supporting Dual Bands for 5G Mobile, FSS, and DBS Communication

Raj Kumar Mistri , Ajit Kumar Singh , Santosh Kumar Mahto , Rashmi Sinha , Ahmed Jamal Abdullah Al-Gburi , Mohd Muzafar Ismail and Khaled Alhassoon

This article presents an 8 × 8 Multiple-Input Multiple-Output (MIMO) antenna system that operates in two frequency bands: 3.4-3.8 GHz and 10.5-14.0 GHz. The core element of this antenna system is a rectangular patch with a line slot. To assess the diversity performance of this MIMO antenna, various parameters like S-Parameters, Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG), Channel Capacity Loss (CCL), Total Active Reflection Coefficient (TARC), and Channel Capacity (CC) were used. The study demonstrates a strong alignment between measurement and simulation results. The article thoroughly analyzes the simulated and measured performances of the lower band (LB) (3.4-3.8 GHz) and upper band (UB) (10.5-14.0 GHz). In the LB, the measured values for parameters such as reflection coefficient, mutual coupling coefficient, TARC, total efficiency, ECC, MEGi-MEGj, CCL, and CC all surpass or equal specific benchmarks. Specifically, these values are better than -6 dB, 10 dB, -11 dB, 56%, 0.15, 0.83 dB, 0.275 bps/Hz, and 38 bps/Hz, respectively. For the UB, the values are also quite favorable, exceeding or closely matching key criteria: -6 dB, 10 dB, -5 dB, 40%, 0.2, 1.6 dB, 0.55 bps/Hz, and 33.6 bps/Hz. These findings suggest that the intended MIMO antenna meets the necessary conditions for both the LB and UB regions. As a result, it appears to be a promising choice for applications in 5G mobile networks and satellite communications, including Direct Broadcast Satellite (DBS) and Fixed Satellite Services (FSS).

An Eight-element MIMO Antenna System Supporting Dual Bands for 5G Mobile, FSS, and DBS Communication

2024-08-01

PIER B

Vol. 107, 105-124, 2024

doi:10.2528/PIERB24060802

download: 161

Iron Loss in Electrical Machine - Influencing Factors, Model, and Measurement

Jiawei Yi , Qinyuan Dong , Jianhua Sun , Lixia Sun , Xiang Li , Hui Hwang Goh , Haisen Zhao , Thomas Wu and Dongdong Zhang

Improving the efficiency of electrical machine is an important way to reduce carbon emissions. Accurate calculation and measurement of iron loss is an important part of improving efficiency of electrical machine. Therefore, how to accurately calculate and optimize the device structure to reduce iron loss has become a research focus. In this study, the influence of power supply, motor structure, ferromagnetic material, manufacturing processes and multiphysics on the motor iron loss is discussed and summarized. Then, the classification and summary of the existing iron loss models are discussed, and shortcomings and the future research direction are suggested. In addition, several induction motor efficiency measurement standards are described, and the defects and improvement direction of efficiency measurement of converter-fed motor are discussed. The contents discussed and summarized in this study can be helpful to engineers engaged in high efficiency motor design and motor driving algorithm development.

Iron Loss in Electrical Machine - Influencing Factors, Model, and Measurement

2024-07-18

PIER B

Vol. 107, 91-103, 2024

doi:10.2528/PIERB24050502

download: 135

Canay Inductance Impact Characterization on Dynamic Behaviour of Synchronous Machines

Farid Leguebedj , Djamel Boukhetala and Madjid Teguar

The conventional synchronous generator model accurately represents only the stator circuit. However, when considering transient effects on rotor quantities such as rotor voltage and current, accurate predictions can be achieved by properly incorporating the field and damper considerations with the stator circuits in an equivalent model. Besides, it has been observed that simulated responses obtained using the conventional model with calculated machine parameters frequently do not align well with the actual measured responses, especially for the rotor winding. This paper analyzes the effect of the d and q axis parameters of synchronous machines, focusing on accurately determining these parameters, particularly the Canay inductance. It investigates the impact of precise determination of these parameters from the time constants of the direct axis operational inductance on transient response and stability. Through simulation studies on a high order model synchronous generator system, the paper compares transient performances with and without considering Canay inductance, shedding light on its effects.

Canay Inductance Impact Characterization on Dynamic Behaviour of Synchronous Machines

2024-07-15

PIER B

Vol. 107, 77-90, 2024

doi:10.2528/PIERB24051404

download: 109

Flexible Discretization of Singular Green Functions Using a Composite Spectral Integration Path

Daan van den Hof , Martijn Constant van Beurden and Roeland Johannes Dilz

Scattering of electromagnetic waves by a dielectric object can be described as an integral equation involving a Green function. These types of problems can be solved using a spatial spectral formulation, which requires sampling of the spectral Green function. To avoid sampling around the singularities on or near the real axis, the spectral Green function is represented on three separate complex paths. Using appropriate selection functions, these paths are recombined such that the original Fourier integrals are retrieved. This composite path method provides a general way to solve domain integral equations involving Green functions with simple singularities with minimal computational overhead.

Flexible Discretization of Singular Green Functions Using a Composite Spectral Integration Path

2024-07-09

PIER B

Vol. 107, 63-75, 2024

doi:10.2528/PIERB24050703

download: 143

Research on Single-Hole Compensated Passive Magnetic Shielding Structure for Electric Vehicle Wireless Power Transfer Systems

Zhongqi Li , Ziyue Gan , Liquan Ren , Bin Li , Pengsheng Kong , Hui Li and Junjun Li

In the wireless power transfer (WPT) system of electric vehicles, reducing the magnetic leakage and minimizing the use of magnetic shielding materials while maintaining transmission efficiency are difficult problems. To this end, a single-hole compensated passive magnetic shielding structure is proposed in this paper, with the system's magnetic leakage reduced and transmission efficiency improved through metal shielding and passive shielding. First, the magnetic shielding principles and design concepts of the magnetic core, aluminum plate, and passive shielding coils are analyzed. The single-hole compensated passive magnetic shielding structure is proposed, and then a mathematical model of the structure is derived. Second, an optimization method is proposed, using Matlab and Ansys Maxwell software to reduce the volume of metallic materials while keeping magnetic leakage within a safe range. Finally, a WPT device based on the proposed structure is constructed according to the optimized magnetic shielding and coil parameters, and the effectiveness of the structure is validated through simulation and experimentation. The results demonstrate that, when the system output power is 4 kW, leakage is reduced by 62.7% compared to the single-hole unshielded coil structure using the same materials with the proposed structure. Compared to the all-aluminum plate and all-magnetic core structure, not only is leakage reduced by 1.2%, but there is also a reduction of 40.4% in magnetic core usage and 30.1% in aluminum plate usage. Moreover, the transmission efficiency reaches 93.49%.

Research on Single-hole Compensated Passive Magnetic Shielding Structure for Electric Vehicle Wireless Power Transfer Systems

2024-07-05

PIER B

Vol. 107, 47-62, 2024

doi:10.2528/PIERB24032802

download: 214

Analysis of a Triple Band MIMO Antenna for Sub-6 GHz Applications

Govardhani Immadi , Madhavareddy Venkata Narayana , Ambati Navya , Aovuthu Sree Madhuri , Burra Vamsi Krishna and Marri Venkata Siva Gopi

A triple band MIMO antenna is designed and analysed at sub-6GHz for 5G applications on an FR-4 substrate. This paper contains the transition of an antenna from a simple microstrip antenna to the proposed defected L-shaped microstrip patch antenna, which comprises single, 2-element MIMO, and 4-element MIMO antennas with permittivity of 4.3, and the dimensions of those antennas are 60 × 60 mm², 60 × 120 mm², and 120 × 120 mm² correspondingly. These antennas resonate at three resonant frequencies which are 3 GHz, 4.1 GHz and 5.2 GHz under sub-6 GHz. HFSS has been used to design these antennas and to obtain the parameters like S-parameters, gain, VSWR and MIMO parameters like ECC, DG, TARC, and MEG. At those resonant frequencies, single element antenna has S₁₁ of -26.83 dB, -20.06 dB, and -19.16 dB; two element MIMO antennas have S₁₁ of -22.7 dB, -40.09, and -20.54 dB; and quad element MIMO antennas have S₁₁ of -15 dB, -24.8 dB, and -22.7 dB. The overall antenna gains are 2.5061 dBi, 3.1903 dBi, and 4.2989 dBi for single, 2-port, and 4-port MIMO antennas. This antenna is well suited for a range of applications including FWA systems that utilize 3 GHz frequency, Smart Cities and connected vehicles that rely on 4.1 GHz, and high-bandwidth activities such as video streaming, cloud computing, and mission-critical communications that require 5.2 GHz. Additionally, it can support future developments in both 5G and Wi-Fi technologies.

Analysis of a Triple Band MIMO Antenna for Sub-6 GHz Applications

2024-07-01

PIER B

Vol. 107, 33-45, 2024

doi:10.2528/PIERB24031701

download: 152

Outage Prediction and Improvement in 6G for UAV Swarm Relays Using Machine Learning

Hisham Khalil , Gauhar Ali , Saeed Ur Rahman , Muhammad Asim and Mohammed El Affendi

The issue of signal outages in sub-THz frequency communication for future 6G networks is addressed by this research. A machine learning method is proposed, employing Random Forest and K-Means algorithms to predict the optimal frequency band and outage probabilities for UAV relays. Both space and frequency diversity are explored to enhance signal strength, and metasurface-carrying UAVs are introduced with a 16 × 16 mm² design. This design significantly reduces the predicted outage probability from 0.1% to 0.0178%. Finally, triangular and hexagonal UAV swarm formations with metasurfaces are investigated, demonstrating improved performance through heatmap results.

Outage Prediction and Improvement in 6G for UAV Swarm Relays Using Machine Learning

2024-06-29

PIER B

Vol. 107, 19-31, 2024

doi:10.2528/PIERB24052703

download: 172

Bandwidth Enhancement Methods Analysis for High-Gain Stacked Microstrip Antenna

Mikhail S. Shishkin

This article presents the results of the bandwidth enhancement method analysis for a stacked microstrip antenna. Based on the analysis results, a new design of a wideband, compact, high-strength antenna is proposed. Antenna operates in a wide frequency band of 4660 to 6048 MHz (~26%) with an impedance bandwidth matching of 15 dB; throughout its whole operating frequency range, the antenna gain is from 11 to 13.4 dBi. The antenna allows it to form a specific shape of radiation pattern with coverage predominantly in the upper (lower) hemisphere and a fixed main lobe deflection angle of about 4 degrees in the elevation plane. The antenna consists of a wideband E-shaped active exciter and four passive rectangular exciters placed above the conductive plane (screen). All elements are made of sheet metal (e.g., stainless steel). The antenna size is 1.4λ_max×1.4λ_max (1.6λ₀×1.6λ₀). The analysis of the characteristics of the designed antenna was per-formed using simulation in the ANSYS EM Suite. A prototype was made, and its properties were measured. The proposed antenna may be designed with a different frequency band with a matching band of about 25% and can be used as a wireless communication system repeater or small cell antenna, as a ground station antenna in unmanned aircraft systems, or for other wideband applications with high gain.

Bandwidth Enhancement Methods Analysis for High-gain Stacked Microstrip Antenna

2024-06-28

PIER B

Vol. 107, 1-18, 2024

doi:10.2528/PIERB24050601

download: 92

Synthesis of Shaped, Reconfigurable, and Envelope Beam for Linear Array Using a Hybrid Whale Optimization Algorithm

Pengliang Yuan

Whale optimization algorithm (WOA) has been demonstrated to be a powerful strategy for various kinds of optimized problems. However, the direct use of WOA to tackle the shaped pattern synthesis can not reach the satisfactory result. To overcome this problem, a hybrid whale optimization algorithm(HWOA) is proposed in this paper, through integrating the invasive weed optimization (IWO) and hyper chaotic system into the standard WOA to improve the population diversity and convergence speed. To demonstrate the performance of HWOA, various runs of tests are conducted for the most widely used benchmark functions. The statistical result shows that the proposed HWOA can attain a superior performance, in comparison with other state-of-the-art algorithms. To investigate the effectiveness and feasibility of the proposed HWOA in the linear array synthesis, the simulation experiments for synthesis of shaped, reconfigurable and envelope pattern in the main and side lobe are done, and the corresponding numerical results are provided. In the shaped beams synthesis, the specified PSLL and maximal ripple are respectively -25 dB and 1 dB, and HWOA has a PSLL improvement of 0.2 dB and a ripple improvement of 0.27 dB. For the reconfigurable beams synthesis, the technique specification is the same as the shaped beams synthesis. The optimal PSLL reaches -25.57 dB, and the optimal ripple is 0.3873 dB. For the envelope synthesis, the main lobe region of line envelop lies in θ ∈ [85°, 95°], and the side lobe levels are decreased from -30 dB to -40 dB along a line. The maximal error of the optimal result is only 0.2dB. In particular, a new form of fitness function to facilitate the envelope synthesis is also presented.