PIER Letters | PIER Journals

2024-08-05

PIER Letters

Vol. 121, 101-105, 2024

download: 99

Development and Measurement of a 3D Printable Radar Absorber

Tobias Plüss , Axel Murk , Diana Vorst , Denis Nötel , Martin Schürch and Peter Wellig

In this paper, we present our measurements about 3D printable microwave absorber materials. First, we determined the electromagnetic parameters of the material using different measurement techniques, whose some examples we present. Knowing the material parameters, a geometry for a 3D printable absorber was selected, and simulations were performed to optimise the geometry from X-band (8.2 GHz to 12.4 GHz) to Ka-band (26.5 GHz to 40 GHz). Pieces of absorbers were 3D printed using the optimised dimensions and were mounted to a metallic corner reflector as test subject. The corner reflector camouflaged in this way was then measured in an anechoic chamber, and measurements with and without the 3D printed absorbers are compared. We found good agreement between the measurements and simulations and found the structure and the material we used as usable candidates for the reduction of the radar cross section of an object.

Development and Measurement of a 3D Printable Radar Absorber

2024-07-19

PIER Letters

Vol. 121, 93-99, 2024

doi:10.2528/PIERL24042505

download: 116

Wearable Metamaterial Inspired Antenna for ISM, WiMAX , WLAN, Wi-Fi 6E(6 GHz ), Aeronautical Radio Navigation and Radio-Location Applications

Navneet Sharma , Himani and Shilpa Srivastava

A compact, spectacle shaped, tri-band, metamaterial inspired antenna is designed for ISM, WiMax, WLAN, Wi-Fi 6E 6 GHz, Aeronautical Radio navigation and Radio-Location Applications. The radiating electrical length is modified by two successive CSRR structures to mitigate the current and create a band notch at 3.9 GHz as well as 5.5 GHz. The proposed prototype is designed on low cost FR-4 material. Antenna performance parameters are investigated on a four-layered phantom model. The results obtained reveal that the antenna works well on free space as well as at the close proximity to human tissues.

Wearable Metamaterial Inspired Antenna for ISM, WiMax, WLAN, Wi-Fi 6E(6 GHz), Aeronautical Radio Navigation and Radio-location Applications

2024-07-17

PIER Letters

Vol. 121, 87-91, 2024

doi:10.2528/PIERL24041405

download: 157

A Novel Three-Coil WPT System with Automatic CC-CV Transition Function

Xuebin Zhou , Yilin Wang , Yuhang Jiang and Lin Yang

In order to prolong the service life of lithium batteries, the charging process is usually divided into two stages: first constant current (CC) charging, and then constant voltage (CV) charging. This letter proposes a three-coil structure wireless power transfer (WPT) system to realize inherent CC and CV characteristics and automatic CC-CV transition function. During charging, the proposed system can operate in S-S-LCC tank for CC charging and in S-S-S tank for CV charging, respectively. Different from the previous closed-loop control, hybrid topology switching and dual-frequency switching methods, the proposed method has automatic CC-CV transition function due to the special circuit structure. Therefore, the communication links, state-of-charge detection circuits and open-circuit protection circuits are omitted, which ensures the high reliability and low cost of the system. Finally, a verification experimental prototype with a rated power of 480 W is built to verify the feasibility of the proposed system.

A Novel Three-coil WPT System with Automatic CC-CV Transition Function

2024-07-17

PIER Letters

Vol. 121, 79-85, 2024

doi:10.2528/PIERL24052601

download: 154

A Dual-Band Four-Port Printed MIMO Antenna with Enhanced Isolation and Polarization Diversity for Midband 5G Applications

Vishnupriya Rajagopalan , Sanish Vaipel Sanu and Stephen Rodrigues

A compact four-port dual-band compact multiple-input multiple-output (MIMO) antenna system with reduced mutual coupling is proposed in this paper. The dual-band antenna operates in the frequency range covering 3.1-3.6 GHz (5G NR, n78) and in the newly introduced 5G midband spectrum of 5.925-7.125 GHz (5G NR, n96). The proposed MIMO antenna system is compact with dimensions 65 × 65 × 0.8 mm³ and has isolation ≤ -20 dB among all ports. The single monopole antenna is loaded with multiple resonant branches designed and optimized with impedance bandwidths of 14.92% at 3.35 GHz and 18.46% at 6.5 GHz. Impedance bandwidth, polarization diversity, and mutual coupling between elements for the designed four-port MIMO antenna system are measured. The proposed design is fabricated using an FR4 epoxy substrate, and the measured gain values are 3.9 dB and 4.8 dB for 3.3 GHz and 6.5 GHz, respectively, with nearly omnidirectional radiation pattern.

A Dual-Band Four-Port Printed MIMO Antenna with Enhanced Isolation and Polarization Diversity for Midband 5G Applications

2024-07-16

PIER Letters

Vol. 121, 71-77, 2024

doi:10.2528/PIERL24050602

download: 147

Inclination Detection of Multi-Mode Orbital Angular Momentum Based on Multi-Label Class-Specific Lightweight Neural Network

Hui Yang , Yifei Cheng , Zhong Yu , Zhe Wang and Yi Lu

Orbital angular momentum (OAM) becomes a new resource for wireless communication due to the different modes being orthogonal. In OAM-based wireless communications, factors such as tilt and multipath distort the phase of the OAM beam, making the mode difficult to detect. We propose a multi-label class-specific lightweight neural network (MCSLNN) to measure tilt and detect mode from a single image. MCSLNN utilizes the MobileNetV2 network as the backbone feature extraction network, considering the terminal devices with limited computing resources. To improve the performance of multi-label classification, MCSLNN employs residual class-specific attention (CSRA) as the classification layer. Furthermore, MCSLNN employs the beam steering method to verify the correctness of the measured tilt. The network measures the tilt angle with an accuracy of 76% and an estimation error of ±1° in a validation experiment. Finally, we analyze the network's generalization from varying heights above the ground for reflection paths. The results indicate that MCSLNN is adaptable to diverse circumstances, thus making it suitable for 6G communication and radar applications.

Inclination Detection of Multi-mode Orbital Angular Momentum Based on Multi-label Class-specific Lightweight Neural Network

2024-07-09

PIER Letters

Vol. 121, 65-69, 2024

doi:10.2528/PIERL23122203

download: 153

Robustness of an All-Optical Limiter to Manufacturing Errors

Frederique Gadot and Geraldine Guida

In this paper, we present a numerical study to assess the robustness of an all-optical photonic limiter based on a two-dimensional (2D PC) TiO2 photonic crystal with a single ZnO nonlinear two-photon absorption (TPA) defect to manufacturing disturbances. These disturbances studied here concern diameters and positions. It is revealed that our limiter configuration is very robust to manufacturing errors.

Robustness of an All-optical Limiter to Manufacturing Errors

2024-07-09

PIER Letters

Vol. 121, 57-63, 2024

doi:10.2528/PIERL24022801

download: 283

Improved Orthogonal Flux Corrector-Based Rotor Flux Estimation in PMSM Sensorless Control

Siyuan Cheng , Haoze Wang and Yajie Jiang

In a permanent magnet synchronous machine (PMSM) system, the voltage mode-based rotor flux observer suffers from DC drift, primarily due to measurement errors, parameter variations, and non-zero initial states. To address this issue, the second-order flux observer (SOFO) is utilized, equipped with filtering capability aimed at reducing harmonic components. However, the DC offset induced by external disturbances cannot be completely eliminated by the second-order transfer function alone. Traditional magnetic flux correctors typically update correction values only at zero-crossing points of the magnetic flux. In this study, we propose an improved orthogonal flux corrector (IOFC) that combines a generalized integrator to effectively filter out the DC offset. In comparison with traditional OFC methods, our approach involves reconstructing two magnetic linkage functions, thereby doubling the correction frequency within a single cycle. Consequently, the frequency of correction term updates is threefold compared to conventional OFC methods. Finally, IOFC is implemented and tested on a PMSM platform for experimental verification.

Improved Orthogonal Flux Corrector-based Rotor Flux Estimation in PMSM Sensorless Control

2024-07-09

PIER Letters

Vol. 121, 51-56, 2024

doi:10.2528/PIERL24031804

download: 212

New THz Notch Filter Based on Cylindrical Periodic Structure

Tarik Touiss , Mohammed Rida Qasem , Siham Machichi , Farid Falyouni and Driss Bria

We propose and numerically analyze a new type of notch filter oper-ating at terahertz frequencies, using a cylindrical periodic structure. This study takes place in the context of increasing demand for precise filtering devices in the terahertz frequency range, crucial for various applications in telecommuni-cations, sensing, and the medical field. This research focuses on the numerical analysis of the proposed structure, using the transfer matrix method to examine how changes in geometric parameters influence wave transmission. Particular attention is given to the effects introduced by the radii of the cylinders making up the structure. The principal results show that perfect symmetry (radii R₁ = R₂) produces no significant transmission dip, indicating the absence of reso-nance in the frequency band studied. This configuration allows the device to function as a passive filter. The introduction of asymmetry (R₁ = R₂) leads to the appearance of transmission dips, meaning that the device functions as a notch filter, capable of blocking specific frequencies. This phenomenon offers a method of selective filtering, by ``activating'' or ``deactivating'' the filter's behav-ior. Our research demonstrates the potential of the proposed cylindrical periodic structure as an innovative solution for the design of notch filters in the THz range. The ability to precisely control wave transmission through geometrical adjustments opens up new ways to develop highly selective filter devices adapt-able to various technological applications.

New THz Notch Filter Based on Cylindrical Periodic Structure

2024-07-06

PIER Letters

Vol. 121, 41-49, 2024

doi:10.2528/PIERL24051302

download: 180

Design and Performance of a Fully-Polarized Tightly-Coupled Patch Antenna for Advanced Phased Array Radar Systems

Jianjun Wu , Zhao Li and Hongbing Sun

A tightly-coupled patch array antenna, capable of broadband operation and low profile, is proposed in this study. The antenna subarray comprises four closely-coupled square patches that rotate in sequence. An impedance matching strip is utilized to achieve broadband matching of the antenna. By configuring the subarray with various feeding phases, it is possible to achieve the switching of six polarization states. The simulated and measured results suggest that the proposed antenna demonstrates a broad impedance matching band ranging from 4.2 GHz to 5.25 GHz (22.2%) over a scanning angle span of ±45˚, while maintaining a low profile of 0.033λ₀. The antenna's inherent simple structure, low profile, wide bandwidth, and favorable radiation characteristics position it as a promising option for multifunction phased array radar systems.

2024-07-02

PIER Letters

Vol. 121, 33-40, 2024

doi:10.2528/PIERL24042404

download: 263

Non-Conformal Design and Fabrications of Single Arm Conical Log Spiral Antenna

Purno Ghosh , Frances Harackiewicz , Liton Chandra Paul and Ashish Mahanta

For a conical log spiral antenna (CLSA), it is quite common to place the strip conductor conformally to the conical surface, and the antenna requires an extra impedance matching network. On the other hand, non-conformal orientation can solve the impedance matching issue, but fabrication is not as straightforward as conformal placement. This work considers the non-conformal placement of a strip conductor which facilitates self-matching while using smart additive manufacturing techniques for prototyping to ease the fabrication complexity. The impact of the additional dielectric support on the performance parameters of CLSA is investigated. Finally, the CLSA was prototyped using two different conductive elements (copper strip and conductive paint) on the 3D-printed support. Experimental and numerical results are shown to agree well for both copper strip and paint-based approaches. The self-matched CLSA provided a maximum impedance bandwidth of 128%, 3-dB axial ratio bandwidth (AR BW) of 63.56%, and gains of 10.32±1.94 dBi. The additive manufacturing techniques are shown to allow design flexibility and mitigate fabrication difficulties.

Non-conformal Design and Fabrications of Single Arm Conical Log Spiral Antenna

2024-06-18

PIER Letters

Vol. 121, 27-32, 2024

doi:10.2528/PIERL24040204

download: 315

Controlling the Polarization Conversion and Asymmetric Transmission Properties of a Metasurface by Controlling the Chirality of Its Unit Cell

Sayan Sarkar and Bhaskar Gupta

Chirality (mirror asymmetry) of the unit cell ensures the phenomenon of polarization conversion in a metamaterial/metasurface. In this communication, we control the polarization conversion and asymmetric transmission properties of a metasurface by controlling the chirality of its unit cells. Radio Frequency PIN diode switches are used to control the chirality. When the switches are turned OFF, the unit cells become chiral, and the metasurface successfully exhibits polarization conversion as well as asymmetric transmission for linearly polarized incident waves. When the switches are turned ON, the unit cells become achiral and lose both the above properties. The polarization conversion switching phenomenon is also observed for circularly polarized incident waves. A simple ultrathin metasurface is designed and fabricated to demonstrate these properties.

Controlling the Polarization Conversion and Asymmetric Transmission Properties of a Metasurface by Controlling the Chirality of Its Unit Cell

2024-06-16

PIER Letters

Vol. 121, 19-25, 2024

doi:10.2528/PIERL24050201

download: 343

Common-Mode Voltage Analyses for Space Vector PWM Based on Double Fourier Series

Jian Zheng , Cunxing Peng , Liangshuai Lin and Kaihui Zhao

Space vector pulse width modulation (SVPWM) is widely used in three-phase inverters. As the performance requirements of inverters increase, there is a demand to suppress common-mode voltages (CMVs) generated by SVPWM. In order to suppress the CMVs, it is necessary to mathematically analyze the CMVs. By using a mathematical analysis method based on double Fourier series, general expressions of CMV harmonic amplitudes and spectra are obtained for seven-segment SVPWM and five-segment SVPWM. Comparative analyses on the CMV general expressions are performed for the two SVPWMs, and the CMV harmonics characteristics for the two SVPWMs are summarized. Simulations are carried out in an inverter-driven permanent magnet motor system, and simulation results are in good agreement with calculation ones, which verifies the correctness and validity of the mathematical analysis. Based on these analyses, a more in-depth research can be conducted on the CMV suppression.

Common-mode Voltage Analyses for Space Vector PWM Based on Double Fourier Series

2024-06-15

PIER Letters

Vol. 121, 13-18, 2024

doi:10.2528/PIERL24042901

download: 243

Analysis and Optimization on Weight Accuracy of the Adaptive Interference Cancellation

Yunshuo Zhang , Songhu Ge , Huanding Qin , Hongbo Liu , Zhongpu Cui and Jin Meng

Weight and reference signal are utilized in adaptive interference cancellation (AIC) for vector weighting to generate the signal with equal amplitude and opposite phase to the interference signal. Weight accuracy becomes the core factor to determine the performance of the AIC. In this letter, we analyze the influence of the weight accuracy on interference suppression performance, propose the quantitative characterization method of the weight accuracy with weight noise as an indicator, study the performance and influencing factors of the weight accuracy, and propose the optimization design method. The characteristics of weight accuracy in interference cancellation are verified by theoretical simulation analysis. This work fills in the blank of weight accuracy analysis and has solid theoretical value for exploring the capability boundary of the AIC.

Analysis and Optimization on Weight Accuracy of the Adaptive Interference Cancellation

2024-06-15

PIER Letters

Vol. 121, 7-12, 2024

doi:10.2528/PIERL24041803

download: 250

Uncertainty Analysis Method for EMC Simulation Based on the Complex Number Method of Moments

Jinjun Bai , Bing Hu , Haichuan Cao and Jianshu Zhou

The Method of Moments (MoM) is a non-embedded uncertainty analysis method that has been widely used in Electromagnetic Compatibility (EMC) simulations in recent years due to its two major advantages of high computational efficiency and immunity from dimensional disaster. A random variable sensitivity calculation method based on the Complex Number Method of Moments (CN-MoM) is proposed in this paper to improve the accuracy of the MoM in standard deviation prediction and thereby enhance the credibility of EMC simulation uncertainty analysis results. In the parallel cable crosstalk prediction example in the literature, the result of the Monte Carlo Method (MCM) is used as the standard, and the accuracy of the new method proposed in this paper is quantitatively verified using the Feature Selective Validation (FSV) method. Compared with the MoM, the proposed method can significantly improve the calculation accuracy of the standard deviation results without sacrificing simulation efficiency.

Uncertainty Analysis Method for EMC Simulation Based on the Complex Number Method of Moments

2024-06-14

PIER Letters

Vol. 121, 1-6, 2024

doi:10.2528/PIERL24040901

download: 305

Design and Implementation of a Millimeter Wave Active Antenna for UAV Communications

Ning Liu , Guanfeng Cui , Guotao Shang , Ruiliang Song and Bo Zhang

The millimeter wave communication technology used for drones could combine the advantages of drones and millimeter waves, providing high-speed data transmission and wide area network coverage capabilities, and has broad application prospects in military and civilian communication systems. Millimeter wave active antennas have the advantages of miniaturization, high frequency band, and flexible shaping, which is of great significance for ensuring the high-speed dynamic communication ability of drone platforms. In this paper, a millimeter wave active antenna suitable for unmanned aerial vehicles (UAVs) is designed and verified, operating in 24.75-27.5 GHz and adopting Antenna in Package (AiP) design. Frequency band test and communication performance test is conducted. To open and close the RF channels, the antenna's operating frequency range can be shown in the vector network analyzer which meets the design frequency band 24.75-27.5 GHz requirements. By loading 5G millimeter wave standard signals, the antenna can achieve real-time demodulation of 100 MHz, 256 QAM signals. The test shows that the system can meet the requirements of beam tracking and real-time information transmission during high-speed dynamic flight of UAVs. It has broad application prospects in UAV communication systems.