Applied Computational Electromagnetics Society Journal (ACES)

Prediction of Antenna Performance based on Scalable Data-informed Machine Learning Methods

Yiming Chen — 2024-04-30

This paper proposes a scalable architecture for predicting antenna performance using various data-informed machine learning (DIML) methods. By utilizing the computation power of graphics processing units (GPUs), the architecture takes advantage of hardware (HW) acceleration from the beginning of electromagnetic (EM) full-wave simulation to the final machine learning (ML) validation. A total of 49152 full-wave simulations of a classical microwave patch antenna forms the ML dataset. The dataset contains the performance of patch antenna on six commonly used materials and two standard thicknesses in a wide frequency range from 0.1 to 20 GHz. A total of 13 base ML models are stacked and ensembled in a tabular workflow with performance as 0.970 and 0.933 F₁ scores for two classification models, as well as 0.912 and 0.819 R₂ scores for two regression models. Moreover, an image-based workflow is proposed. The image-based workflow yields the 0.823 R₂ score, indicating a near real-time prediction for all S₁₁ values from 0.1 to 20 GHz. The proposed architecture requires neither the fine-tuned hyperparameters in the ML-assisted optimization (MLAO) model for specified antenna design nor the pre-knowledge required in the physics-informed models. The fully automated process with data collection and the customized ML pipeline provides the architecture with robust scalability in future work where more antenna types, materials, and performance requirements can be involved. Also, it could be wrapped as a pre-trained ML model as a reference for other antenna designs.

Optimal Synthesis of Unequally Spaced Linear Arrays under Multiple Constraints

Zhong-Hui Zhao — 2024-04-30

This paper proposes a differential evolution modified with adaptive ε-constraint handling and whale optimization algorithm (ε-WOA-DE) for the synthesis of unequally spaced linear arrays under array layout constraints and array pattern characteristics constraints. In particular, the success history based adaptive differential evolution with linear population reduction (LSHADE) serves as the basic search engine in this study. To ensure the searching ability of LSHADE under multiple constraints, an adaptive ε-constraint handling technique is implemented in LSHADE, in which the epsilon level is adjusted dynamically to make the solution scalable to the feasible region when it is in the infeasible region. In addition, the WOA mutation is implemented in the LSHADE to enhance the local search capability. Two array synthesis examples with multiple constraints are chosen to demonstrate the effectiveness of the proposed algorithm. The simulation results comparison and the convergence analysis of the ε-WOA-DE illustrate the superior capability of the proposed method.

High-order Mode of Spoof Surface Plasmon Polaritons based on a Novel Compact Structure and its Application in Band-pass Filters

Siyu Yang — 2024-04-30

In this paper, two band-pass filters based on the high-order mode of spoof surface plasmon polaritons (SSPPs) are introduced. A novel compact bow-folded strip is proposed as a cell, which exhibits perfect band-pass characteristics. By adjusting the width and groove of the bow-folded strips, high-order mode can be obtained to support the design of band-pass filters. Compared to the conventional single-side rectangular groove SSPPs cell, our proposed bow-folded strip structure cells reduce the electrical size by 59% and 70% at the same cut-off frequency. In addition, the transmission lines of the two proposed band-pass filters are microstrip lines and their over-conversion structures are simple trapezoidal over. A single-band and a dual-band band-pass filters using the proposed SSPPs cell are fabricated and measured, both having almost the same size. The measured results are in good agreement with simulated results, which verify the feasibility of our design.

Investigation on Pulse Radiation Characteristics of Discretized Apertures in Time-domain

Binwen Wang — 2024-04-30

In view of the challenges and difficulties encountered in the analysis and application of time-driven ultra-wideband array antennas (TD-UWB arrays), this study investigates the pulse radiation characteristics of discretized apertures based on aperture radiation theory and space superposition principle. The impact of discretized aperture linear arrays and planar arrays to restore the radiation of original aperture is examined, along with an analysis of how discretization methods influence the radiated pulse waveforms. The potential application of discretized aperture radiation in research of TD-UWB array antennas is studied, and a method is proposed for predicting time-domain radiation characteristics of TD-UWB arrays. Numerical results demonstrate that the proposed method derived from the discretized aperture radiation can effectively predict the temporal pattern and radiation waveforms of TD-UWB arrays. The research expands and advances the practical applications of aperture radiation, thereby offering a novel perspective for analyzing the radiation characteristics of TD-UWB arrays.

Performance Analysis of Eight-element MIMO Mobile Phone Antenna for Sub-6 GHz 5G Applications

Dhananjeyan Rajendran — 2024-04-30

This paper presents an 8-port MIMO antenna array for use with 5G handsets. The proposed MIMO antenna array comprises eight U-shaped, coupled-fed slot antenna components placed symmetrically on a 0.8 mm thick FR4 substrate. Each antenna has 200 MHz bandwidth and covers 3.4-3.6 GHz. The operational frequency range includes LTE band 48 for 5G cellular applications. Using spatial and polarisation diversity, antenna components are isolated by over 15 dB. The prototype antenna is fabricated and measured, and the experimental results agree with the simulated results. The estimated Envelope Correlation Coefficient (ECC), less than 0.035 based on radiation characteristics, shows that the suggested MIMO antenna array performs well in diversity. These characteristics indicate that the proposed MIMO antenna is a viable solution for 5G smartphone applications.

Metamaterial-filled Quarter Circular Microstrip Antenna in the Subwavelength Scale for 3.5 GHz Band Communications

Hao Lu — 2024-04-30

A metamaterial-filled quarter circular microstrip antenna (meta-QCMSA) is proposed for 5G communications in the 3.5 GHz band. Compared with traditional CMSAs, the new meta-QCMSA is superior in its small patch in the subwavelength scale realized by collaboratively using metamaterial and field symmetry techniques. This combination method is observed to be more powerful than a single method solely used. One practical meta-QCMSA is designed and experimentally demonstrated near 3.5 GHz. Its patch length is 0.1λ₀, much smaller than the traditional CMSA. In addition, the compact meta-QCMSA is observed to have a considerable bandwidth of 3.8% and antenna gain of 3.9 dBi in experiments.

A Compact Wideband Branch Line Coupler for Lower 5G Applications

Balasem S. Samet — 2024-04-30

This paper presents a new design approach of a compact wideband branch line coupler based on waveguide technique at 3.5 GHz. At the lower band of 5G technology, microwave devices such as hybrid couplers tend to be narrower in bandwidth and big in size, in addition to the phase difference error produced by using common planar technology. Therefore, waveguide technology aims to solve those challenges. This work aims to design a compact wideband coupler by implementing a direct coupling aperture between two waveguides with a cutting in the narrow wall of the structure. This technique helps in obtaining a wide bandwidth and reduces the size of the whole structure. The coupler is simulated using computer software technology and fabricated using CNC machining. The measured S-parameters of the coupler are observed to have low loss properties with return loss and isolation less than −10 dB. The coupling factor at the outputs are −3.21 dB with low loss of −0.2 dB. The measured phase error is about 2^∘ at 3.5 GHz. A size reduction of 70% is observed compared to conventional waveguides and planar couplers. Overall, this coupler shows great performance that could be used for 5G beamforming applications.

Research on Variable Direction Wireless Power Transfer System based on Auxiliary Coils:

Feihang Xiao — 2024-04-30

In complex environments such as mines and pipelines, wireless power transfer (WPT) technology stands as a safe and convenient method for supplying power. However, in practical applications, the unavoidable angular misalignment between the sending and receiving coils results in decreased power. To address this issue, this paper proposes a variable direction WPT design method based on auxiliary coils. The mutual inductance of the system is analyzed with coils placed at different positions and incorporating multiple auxiliary coils. This paper conducts simulation and experimental analysis based on a 45^∘ angle between the horizontal shaft and the slant shaft, showing a 14.92% increase in received power. The effectiveness of the proposed design method validates the feasibility of the technology and offers substantial support for practical applications.

Design of Wideband 8×8 Butler Matrix using Composite Right/Left-handed Transmission Line for Multi-mode OAM Generation

Yan Zhang — 2024-04-30

In this paper, a wideband Butler matrix for the uniform circular array antenna (UCA) generating multi-mode orbital angular momentum (OAM) vortex wave is designed. Firstly, the novel network topology of a Butler matrix is proposed. For the purpose of design and optimization convenience, the 8×8 Butler matrix is separated into two different sub 4×4 Butler matrix modules and one connection-output module. Then several wideband microwave components used in a Butler matrix, such as 3 dB directional coupler and stable phase shifter with composite right/left-handed (CRLH) transmission line, are designed. To demonstrate the effectiveness of the design process, a Butler matrix working in 5-7 GHz is designed and fabricated. It is found that the simulation results are in good agreement with the measured data. The constant amplitude distribution and progressive phase differences of ±45^∘, ±90^∘ between the output ports are observed, hence the ±1, ±2 mode OAM waves can be generated by the proposed Butler matrix.

Selective Microwave Wireless Power Transfer to Sensors Embeddedin Concrete at Sub-wavelength Spacing using ElectromagneticTime-reversal Technique

Baidenger Agyekum Twumasi — 2024-04-30

Wireless power transfer has become a trending research area for remotely transferring power. This paper presents the numerical simulation study of selective wireless power transfer to closely spaced wireless sensors embedded in reinforced concrete. A selective microwave wireless power transfer is achieved at a 10 mm separation between tightly-coupled monopole antennas (wireless sensor antennas). Both tightly-coupled wireless sensors operate at 2.45 GHz, hence beating the diffraction limit at λ/12 with the incorporation of additional scatterers in the reinforced concrete environment. The main objective is to realize selective wireless power transfer to wireless sensors with subwavelength separation (closely spaced) to which one makes the power request. Here, the presence of meta-structures creates some randomness serving as scatterers in the use of the electromagnetic time-reversal technique which enhances the spatial refocusing beyond the diffraction limit. This implies that the focal spot is less than half of the carrier wavelength at the operating frequency. At any time that one of the tightly-coupled sensor antennas sends a power request, power will be transferred to it alone. Cases of dry concrete with and without reinforced bars have been studied with electromagnetic time-reversal techniques for the closely spaced sensors embedded in concrete.