PIER Letters | PIER Journals

2024-06-13

PIER Letters

Vol. 120, 103-107, 2024

download: 108

DOA Estimation Based on Extended Array Using Cyclic Spectral Components

Zhangsheng Wang , Shuiwei Liu and Lei Tang

The paper addresses how to improve the degree of freedom of array for DOA (direction of arrival) estimation. According to the DOA estimation model for cyclostationary signal, a method of constructing virtual extended array based on two cyclic spectral components using a single uniform linear array and a method of estimating DOA based on the virtual array are proposed. Firstly, two array receiving data matrices of uniform linear arrays are constructed by using cyclic autocorrelation function of two different cyclic frequencies. Then, the array receiving data matrix of the virtual nested array is constructed by the Kronecker product of the two linear array receiving data matrices. Through virtual expansion, an M²-dimensional array receiving data matrix is obtained based on a uniform linear array of M-array elements, so that the direction of arrival of M²-1 sources can be estimated. It breaks the limitation of array degrees of freedom. Finally, the direction finding model for the virtual nested array is formulated, and the compressed sensing algorithm is used to estimate the DOAs of sources. Through computational simulation experiments, the performance of the algorithm is verified.

DOA Estimation Based on Extended Array Using Cyclic Spectral Components

2024-06-13

PIER Letters

Vol. 120, 95-101, 2024

doi:10.2528/PIERL24040501

download: 158

A Compact Two-Port Vivaldi-Based MIMO Antenna with High Isolation for C and X Bands Applications

Rong Li , Haoyu Zhang , Yanhong Xu and Jianqiang Hou

This paper presents a broadband high-isolated MIMO antenna operating in the C and X bands simultaneously. The antenna is expected to be applied in wireless systems such as satellites and radar. A modified Vivaldi element is firstly designed by etching a rectangular structure out of the top metal, and then arranged symmetrically to form a 2-element broadband MIMO antenna with element spacing of 0.28λ (λ is the wavelength at 9 GHz). The operating frequency the MIMO antenna in terms of S₁₁ ≤ -9.0 dB is from 4.0 GHz to 13.5 GHz. However, the mutual coupling between the two elements is quite strong, which can be as high as 8.0 dB, indicating a severe mutual coupling effect between the elements. To improve the isolation level, a defect-ground structure (DGS) is designed and loaded on the ground plane. The decoupling structure of the DGS achieves decoupling in the C and X bands, with a particular emphasis on decoupling in the C band by blocking the current flow between antenna elements. The simulated result shows that the S₂₁ can be lowered to less than -23.4 dB across the whole operating frequency region, i.e., an isolation improvement of 15 dB is achieved. A prototype is fabricated and measured. The measured results are in good agreement with the simulated ones, indicating that the designed broadband MIMO antenna is a good candidate for reliable communication in the C and X bands.

A Compact Two-port Vivaldi-based MIMO Antenna with High Isolation for C and X Bands Applications

2024-06-12

PIER Letters

Vol. 120, 89-93, 2024

doi:10.2528/PIERL24022703

download: 122

Compact Double Layer Two via Electromagnetic Band Gap Structure for RCS Reduction

Rajesh Bhagwanrao Morey and Sunil Nilkanth Pawar

In this paper, a multi-layered mushroom-type electromagnetic band gap (EBG) structure is proposed. A double layer two via EBG (DLTV EBG) structure is designed at 1.65 GHz. The proposed DLTV-EBG structure consists of a two-layer dielectric substrate, which reduces the lateral sizes due to a multilayer topology. By adjusting the patch dimensions and positions of the vias, the center frequency, and equivalent L and C parameters meet design requirements. In a DLTV-EBG, layer-1 has a square ring patch; layer-2 has a circular ring; outer square ring patch with 2 edged located vias gives the additional capacitance and inductance to achieve compactness. The simulation of the DLTV-EBG structure is carried out using the Ansys high-frequency structure simulator (HFSS) and experimentally validated. The band gap of the DLTV-EBG structure is measured using suspended microstrip line (SML) method. The Experimental results agree well with simulation one. The periodic size of the proposed DLTV-EBG structure is 0.05λ_{1.65 GHz}, which is a good candidate where compact size is highly desired.

Compact Double Layer Two via Electromagnetic Band Gap Structure for RCS Reduction

2024-06-12

PIER Letters

Vol. 120, 81-88, 2024

doi:10.2528/PIERL24032601

download: 142

Analysis and Optimization of a Wavy Rotor FRM with Curved Stator Slots

Manru Shen , Libing Jing and Zeyu Min

Flux reversal machine (FRM) belongs to the stator permanent magnet (PM) machine, which has the advantages of high reliability, high efficiency, and simple structure. However, large torque ripple and low torque density limit the development prospect of FRMs. Therefore, a wavy rotor FRM (WR-FRM) with curved stator slots is proposed, which can reduce the torque ripple while improving the average torque. The top surface of the rotor tooth consists of three sinusoidal functions, and the stator slots are constructed with a spline curve. To obtain better electromagnetic performance, the multi-objective genetic algorithm is used to optimize the FRM and the WR-FRM. Finally, the electromagnetic performances of the two machines are analyzed and compared by the finite element method. The results show that compared with the FRM, the torque generated by the unit volume of PM is increased by 36.47%, and the torque ripple is reduced by 62.7%.

Analysis and Optimization of a Wavy Rotor FRM with Curved Stator Slots

2024-06-12

PIER Letters

Vol. 120, 73-79, 2024

doi:10.2528/PIERL24030201

download: 162

Low-Profile Circularly Polarized Dual-Beam Holographic Antenna

Lanzheng Liu , Jincheng Xue , Ao Ni , Zhuopeng Wang and Mingxiang Pang

This paper presents the design of a low-profile circularly polarized dual-beam holographic antenna. Firstly, by employing a novel outer square inner circular (OSIC) structure as the basic unit of the hologram pattern, better performance is achieved for low-profile dielectric substrate holographic antennas. Secondly, a method of four-zone phase co-modulation is used to derive the impedance modulation formula of the hologram pattern. This formula was employed to model and generate a circularly polarized dual-beam holographic antenna, and the feasibility of theoretical analysis is verified through simulation and measurement. The antenna operates within the frequency range of 10.23 GHz to 16.59 GHz, with maximum gains of 16dBi and 15.8dBi for dual beams, respectively. The results indicate that this design method can realize circularly polarized dual-beam holographic antennas and provide some reference for satellite communication applications.

2024-06-11

PIER Letters

Vol. 120, 65-71, 2024

doi:10.2528/PIERL24040301

download: 144

A Compact Wide-Band Circular Slot Quad-Port MIMO Antenna for 5G Wireless Applications

Purushothaman Janaki Ramal , Syed Nawab Syed Althaf , Kannan Vishnulakshmi , Palaniselvan Sundaravadivel and Rajesh Kumar Dhandap

This paper introduces a 4-port antenna tailored for 5G, operating in the 4.4 to 7.25 GHz (Fractional Bandwidth is 48.9%) range with a 10 dB impedance bandwidth. The operating bandwidth includes the n79 band (4.4-5 GHz), 5G WLAN band (5.125-5.825 GHz), and Wi-Fi 6E band (5.925 to 7.125 GHz). Constructed on a compact FR4 substrate (0.057λ × 0.057λ × 0.0018 λ (where λ is the wavelength at 4.4 GHz), it exhibits robust performance in fabrication and measurements. The single antenna covers a total area as small as 20 × 17.6 mm², which enables the compactness of the MIMO antenna with a gain of up to 6 dBi and 85% radiation efficiency; it supports MIMO with a low correlation coefficient (< 0.02), high diversity gain (up to 9.98 dB), and minimal channel capacity loss (0.25 bps/Hz). The Total Active Reflective Coefficient (TARC) is computed to validate MIMO performance over the operating bandwidth. Featuring bidirectional radiation patterns in both E-plane and H-plane, the antenna is well suited for 5G applications, demonstrating potential for future wireless systems.

A Compact Wide-band Circular Slot Quad-port MIMO Antenna for 5G Wireless Applications

2024-06-07

PIER Letters

Vol. 120, 59-64, 2024

doi:10.2528/PIERL24040605

download: 130

Broadband Cross-Coupled Filter Based on CPW Structure and Triangular SIW Resonant Cavity

Xiaohei Yan and Minjie Guo

This paper proposes a cross-coupled filter that utilizes a coplanar waveguide (CPW) resonator and triangular substrate-integrated waveguide (TSIW) resonant cavities. The filter consists of a CPW resonator etched on the upper metal surface of a second-order triangular SIW resonant cavity. By adjusting the dimensions of the CPW resonator and optimizing the width of the inductive coupling window, precise control can be achieved over cross-coupling between resonators, enabling fine-tuning of both filter bandwidth and transmission zero placement. Simulation and test results indicate that the filter has a center frequency of 11.85 GHz, a -3 dB bandwidth of 1.82 GHz, a relative bandwidth of 15.4%, an insertion loss of -0.9 dB in the passband, a return loss of over 15 dB, and a transmission zero point located at 15 GHz. The filter has a simple structure, wide bandwidth, low insertion loss, small circuit size, and a flexible and controllable transmission zero point, making it potentially valuable for various applications.

Broadband Cross-coupled Filter Based on CPW Structure and Triangular SIW Resonant Cavity

2024-06-06

PIER Letters

Vol. 120, 53-58, 2024

doi:10.2528/PIERL24041402

download: 143

Broadband Generation Orbital Angular Momentum Beams Based on Uniform Phase Error Analysis of Uniform Circular Array

Na Li , Lingling Jiao , Guirong Feng , Ping Li and Xiao-Wei Shi

In this paper, we propose a method for generating broadband orbital angular momentum (OAM) beams, utilizing the two neighboring ports of the uniform circular array (UCA) excited with a phase difference of (2(π+δ)l)/N. This approach differs from current arrays used to generate an OAM beam with a phase difference of 2πl/N. We establish that the UCA can produce OAM beams covering 83% (7-17 GHz) of the bandwidth. The array antenna consists of three Vivaldi elements with a phase difference between adjacent ports, capable of generating OAM beams of mode 2 when being fed with equal amplitude and phase. In contrast to current OAM antenna arrays that require complex phase-shifting networks for feeding, our proposed antenna array offers simplicity in its feeding mechanism. Furthermore, the UCA-based Vivaldi antenna presents a novel approach for generating wideband OAM beams and holds significant potential for applications in broadband communication.

Broadband Generation Orbital Angular Momentum Beams Based on Uniform Phase Error Analysis of Uniform Circular Array

2024-06-04

PIER Letters

Vol. 120, 47-52, 2024

doi:10.2528/PIERL24021701

download: 191

Interdigital Coupled Compact FSS Reflector for UWB Antenna Gain Enhancement

Gobinda Sen and Santanu Das

A compact UWB FSS reflector is presented based on an interdigital structure for gain enhancement of a UWB antenna. An equivalent circuit approach is proposed for the analysis of the FSS reflector. The reflector comprises a 6 × 6 array of unit cell dimension 6 mm × 6 mm and is very compact. The reflector gives a linear phase response over UWB. A UWB monopole antenna is designed with a half circular disc structure based on microstrip technology. A maximum of 5 dBi gain enhancement is achieved with this compact FSS reflector when it is placed at a distance below the antenna. The measured results closely follow the simulated ones which proves feasibility of this design.

Interdigital Coupled Compact FSS Reflector for UWB Antenna Gain Enhancement

2024-05-31

PIER Letters

Vol. 120, 39-45, 2024

doi:10.2528/PIERL24032604

download: 174

A Topology Reconstruction Based WPT System with CC and CV Outputs Function

Xuebin Zhou , Yonghong Tan , Linhui Wang and Lin Yang

Constant current (CC) charging and constant voltage (CV) charging are the two main charging stages of lithium-ion batteries in wireless charging systems. The traditional LCC-LCC topology has a high degree of design freedom. The conversion from CC to CV output is usually achieved through composite topology or frequency switching, which results in high control complexity and increases system cost. This paper proposes a wireless power transfer (WPT) system with CC and CV output characteristics based on topology reconstruction. Based on the LCC-LCC topology, by introducing one MOSFET in the rectifier and one AC switch which consists of two MOSFETs connected in reverse series to reconfigure the topology, the conversion from CC to CV mode can be achieved without complicated control methods and additional components. In addition, the proposed system works at a fixed operating frequency point, which can effectively avoid frequency bifurcation phenomenon. Therefore, the proposed system features a simple structure, easy control, low cost, and high robustness. In addition, ZPA operation can be realized in both CC and CV modes, ensuring high transmission efficiency. An experimental prototype with a rated power of 480W is built, and a maximum efficiency can reach 93.5%, which verifies the feasibility of the system.

A Topology Reconstruction Based WPT System with CC and CV Outputs Function

2024-05-29

PIER Letters

Vol. 120, 31-37, 2024

doi:10.2528/PIERL24011102

download: 149

Analysis of Slot Antenna Performance for on-Body to in-Body Channel Characterization

Suresh Babu Thandullu Naganathan , Packirisamy Thirumaraiselvan , Anumuthu Priya and Pethaperumal Muthukannan

The propagation study of electromagnetic (EM) waves within a human body is becoming essential due to the growing demand for the design and development of implantable sensing nodes in a body area network (BAN). Many researchers are interested in contributing to the development of propagation models in the ultra-wideband (UWB), i.e. 3.1 to 10.6 GHz, for biomedical applications, as well as the license-free Industrial, Scientific, and Medical (ISM) band. This kind of propagation model is essential in order to design and develop UWB transceivers for in-body, on-body, and off-body communications. This paper looks at the possibility of using a stepped slot patch antenna with a copper ground plane as either an off-body or on-body antenna by comparing measurements taken on a liquid human phantom. In addition, we use the empirical data to propose a statistical model.

Analysis of Slot Antenna Performance for On-body to In-body Channel Characterization

2024-06-08

PIER Letters

Vol. 120, 23-29, 2024

doi:10.2528/PIERL24040103

download: 259

Design of Superconducting h -Shaped Microstrip Antennas on Anisotropic Substances Using Hybrid Cavity Model

Mohamed Bedra , Djemai Arar , Djamel Benatia , Sami Bedra and Akram Bediaf

This study investigates the effects of various antenna parameters, such as the substrate material, thickness of the superconducting patch, and operating temperature, on the resonance frequency and surface resistance/reactance of an H-shaped patch antenna printed on a uniaxial anisotropic substrate using a hybrid cavity model and fabricated with superconductor material. This model stands out for its simplified mathematical approach and cost effectiveness. Importantly, the numerical results demonstrate a high level of agreement with the experimental findings reported in the literature, reinforcing the reliability of our study. Additionally, other numerical results demonstrate the impact of the superconductivity materials on the resonant characteristics of the H-shaped compact microstrip antenna.

Design of Superconducting H-shaped Microstrip Antennas on Anisotropic Substances Using Hybrid Cavity Model

2024-05-22

PIER Letters

Vol. 120, 15-21, 2024

doi:10.2528/PIERL24041202

download: 253

Optically Transparent Broadband Microwave Absorber with Tunable Absorptivity Based on Graphene-ITO Structure

Shuomin Zhong , Enbang Yu , Yu Zhang , Xianjia Chen , Zi-Wei Zheng , Qiping Lin and Sailing He

In this study, we present a novel broadband microwave absorber that is both optically transparent and capable of dynamically adjusting its absorptivity. The absorber is composed of a graphene sandwich structure (GSS), a polyvinyl chloride (PVC) layer, an indium tin oxide (ITO) layer, another PVC layer, and an ITO ground plane, arranged in a top-to-bottom configuration. This unique design allows for a working bandwidth of 6.8 GHz to 14.0 GHz, with absorption levels ranging from 95% to 60%, achieved by varying the impedance of the GSS from 1000 Ω/sq to 200 Ω/sq through tuning the bias voltage. By utilizing materials with high optical transmittance, this nonpatterned device maintains exceptional optical transparency. Furthermore, by incorporating additional ITO layers with different impedances at equal intervals, this multilayer design can be extended to create an ultra-broadband absorber covering a range of 5.28-39.52 GHz. This is made possible due to the dispersionless resistance of nonpatterned graphene and ITO sheets in the microwave spectrum. This transparent wideband microwave absorber, with tunable absorptivity, holds great potential for a wide range of applications in broadband and intelligent stealth technology.

Optically Transparent Broadband Microwave Absorber with Tunable Absorptivity Based on Graphene-ITO Structure

2024-05-21

PIER Letters

Vol. 120, 7-13, 2024

doi:10.2528/PIERL24030408

download: 263

Importance of Functional Parameters on the Effective Operation of Resonant Multi-Receiver Wireless Power Transfer System

Pragyan P. Mohanty , Suraj Kumar Panigrahi , Sushree Sangita Biswal , Sivnarayan Bhuyan , Durga Prasanna Kar , Renu Sharma and Satyanarayan Bhuyan

The magnetic resonance coupling based wireless power transfer (WPT) technology has been of great interest due to its usefulness and persistent characteristics in powering multiple devices simultaneously. However, it is the foremost challenge to make possible easy access and manage the effective power transmission to the multiple gadgets through the WPT technology. In order for the multi-receiver system to run at its most favourable operational area, a prompt access is necessary at this point to identify the appropriate selection of functional parameters. Thus, a circuit model analysis has been put forward, and the influences of functioning parameters such as electric load at the receivers, mutual coupling between the coils, frequency of operation on the system's performance indicators like input power, power at the receiver's load, power transfer efficiency at individual receiver, and moreover the input impedance of the system have been investigated. The perception has been validated through a bench-top experimental setup. The observed experimental result closely matches the theoretical data derived from the circuit model. The outcomes are crucial which may provide the important selection criteria for the effective operation and creation of successful electromagnetic coupling based multi-receiver WPT system.

Importance of Functional Parameters on the Effective Operation of Resonant Multi-receiver Wireless Power Transfer System

2024-05-21

PIER Letters

Vol. 120, 1-6, 2024

doi:10.2528/PIERL24031107

download: 211

Metamaterial-Based Compact UWB Bandpass Filter Using Substrate Integrated Waveguide

Senathipathi Udhayanan and Krishnan Shambavi

A compact ultra-wideband (UWB) bandpass filter is realized with the combination of dual-split square complementary split ring resonator (DSS-CSRR) and substrate integrated waveguide and is investigated in this paper. Three DSS-CSRRs are carved on the top and bottom layers of SIW to achieve the required passband and enhance the selectivity of the filter. Slots are etched in the ground to improve the return loss characteristics and to lower the insertion loss. The proposed filter offers a fractional bandwidth of 107% (3.1-10.3 GHz) and an insertion loss range of 0.6-1.6 dB in the entire passband. The prototype was fabricated on an FR-4 substrate, with dimensions of 0.3λ_gL × 1.06λ_gW. The group delay variation is almost flat over the entire passband. The prototype was fabricated and validated the measured results.