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Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Optical vortex beams carrying orbit angular momentum have attracted significant attention recently. Perfect vortex beams, characterized by their topological charge-independent intensity profile, have important applications in enhancing communication capacity and optimizing particle manipulation. In this paper, metal-insulator-metal copper-coin type reflective metasurfaces are proposed to generate perfect composite vortex beams in X-band. We introduce the qualified equivalent circuit model based on the theory of transmission line to design the meta-atom of the structure. The experiments are performed to measure the far-field and near-field perfect composite vortex beams and evaluate their orbital angular momentum purity at different frequencies. The experimental results agree well with the theoretical predictions. This work provides new ideas and methods for generating high-quality metasurface-based perfect composite vortex beams in the microwave region, paving an ideal path for microwave communication systems, optical manipulation and radar detection. [ABSTRACT FROM AUTHOR]

A broadband millimeter wave absorber is designed using multilayered ultra-thin ε-GaδFe2−δO3 nanomagnets in the V-band, where δ is the doping level of the gallium into the host ε-Fe2O3 material. Four different doping levels are considered to build four kinds of ε-GaδFe2−δO3 nanomagnets, which are further stacked as a four-layer broadband absorber. Its absorption properties are theoretically studied using the lossy transmission line theory. Results show that the four-layer nanomagnets can absorb over 90% of perpendicularly incident power from 50.7 to 74.9 GHz in the V-band. The proposed multilayered absorber is ultra-thin with the total thickness of 351 μm. It is only 0.059λL, where λL is the wavelength at the lowest frequency 50.7 GHz. The robustness of the absorbing performance is also studied by slightly varying the four-layer nanomagnets' doping levels and layer thickness from the default setting. [ABSTRACT FROM AUTHOR]

Multifunctional structures with excellent wave-absorbing and load-bearing properties have attracted much attention in recent years. Unlike other wave-absorbing materials, honeycomb wave-absorbing materials have appealing radar absorption and mechanical properties. However, the existing honeycomb wave-absorbing materials have problems such as narrow absorption band and poor compression resistance. In this study, a novel frequency selective surface-enhanced composite honeycomb absorbers (FSS-CHAs) are fabricated by combining a honeycomb structure with wonderful load-bearing capacity and FSS through screen-printing and inlay-locking techniques. After reflectivity measurements, the effective absorption band (RL < −10 dB) of CHA is 6.25–17.47 GHz and a bandwidth of 11.22 GHz, the effective absorption band of the FSS-CHA is 3.96–18 GHz and a bandwidth of 14.04 GHz, 25.13% improvement compared to the CHA, the mechanism of wave absorption is explained using transmission line theory. The simulation results show that the wide bandwidth is due to the different absorption mechanisms of FSS-CHA at low and high frequencies. The compression test shows that the compression strength of FSS-CHA is 17.10 MPa. In addition, FSS-CHA has a low cost of only USD 270.7/m2. This study confirms the possibility of combining FSS with radar-absorbing honeycombs, which provides a reference for the design of future broadband wave-absorbing structures, offers a novel approach to integrating FSS with CHA, and aims to optimize their efficacy and utility in stealth technology. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to obtain graphene composite materials with good microwave absorption performance, Fe3O4 particles were prepared by a coprecipitation method, and then combined with carboxymethyl cellulose (CMC) to prepare Fe3O4/CMC particles. Then, Fe3O4/CMC was successfully combined with graphene oxide (GO) through ultrasonic oscillation to prepare Fe3O4/CMC/GO composite materials. The structures and morphologies of the materials were characterized by x-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM), and the results showed that spherical Fe3O4/CMC particles were uniformly distributed on the surface of GO. The electromagnetic parameter testing of Fe3O4/CMC/GO composite materials in the range of 2–18 GHz revealed that the magnetic loss mechanism was mainly natural resonance loss and exchange resonance loss. What is more, its microwave absorption performance was calculated by using line transmission theory. The microwave absorption performance of the composite showed that the composite had excellent microwave absorption ability when the weight ratio of Fe3O4/CMC to GO was 3:1. When the thickness of the composite material was 3.5 mm, the minimum reflection loss reached − 36.82 dB, indicating that over 99.9% of the microwaves were absorbed by the composite material, and that the effective absorption bandwidth was 6.10–8.52 GHz, reaching 2.42 GHz. [ABSTRACT FROM AUTHOR]

In this letter, a miniaturized U-shaped microstrip filter based on a load-coupled open line is proposed. It is composed of a step impedance resonator and parallel coupled open stub line. Interfinger feed is used to enhance coupling. This configuration and coupled open stub lines form four transmission zeros between two passbands as part of open coupled stub lines to increased out-of-band rejection. The analysis of formation reason of transmission zero is conducted using lossless transmission line theory and even-odd mode analysis techniques. A filter operating at 2.53 GHz and 5.53 GHz is simulated and fabricated. The insertion loss of first passband is 1.30 dB, and return loss is -18.60 dB. The insertion loss of the second passband is 0.70 dB, and return loss is 22.89 dB. The out-of-band rejection is maintained below -20.00 dB. The final model size is 0.20λg × 0.23λg. The final physical measurement results confirm theoretical results. [ABSTRACT FROM AUTHOR]

Abstract Implementation of reconfigurable metasurfaces demands a complex structure. The design methodology for metasurface elements based on PIN diodes requires targeted optimisation tailored to the varying application environments and cannot be directly transplanted from one methodological approach to another. In addition, inclusion of varactors often imposes undesirable high‐power consumption with complex analog drive circuitry. Furthermore, the design method for the reconfigurable metasurface element has not been simplified and unified, hindering the rapid deployment of metasurface applications. The authors propose a general design model based on low‐power embedded circuitry for a multi‐function metasurface element and give the corresponding numerical analysis. The authors present a reconfigurable method based on the general design model and prove that the method achieves independent regulation of amplitude and phase for the reflected electromagnetic wave. Through analysis of the sensitive area at the bottom of the embedded circuit, a gradient descent algorithm is proposed to find the optimised phase points according to device sensitivity of the application scenario and suitable strategy. Finally, the authors demonstrate that the designed metasurface element possesses phase control capability and decent phase consistency obtained via far‐field scanning experiments. The proposed element design method will provide a theoretical reference for the integrated design of metasurface.

In this paper, we present the design and equivalent circuit model (ECM) of a fractal slot-loaded super wideband (SWB) antenna for compact and high-performance applications operating in the 3–40 GHz range. The proposed antenna features a compact dimension of 40 × 35 × 1.57 mm³, a measured bandwidth ratio of 13:1, a peak gain of 9.7 dBi, an average radiation efficiency of 94%, and a low cross-polarization level across the entire bandwidth. The presented ECM is derived using transmission line theory and incorporates the individual behavior of each constituting element of the antenna. A dual sequential optimization approach is employed to determine the optimal element values. The ECM results show good agreement with both simulated and measured results in terms of the magnitude of reflection coefficient | S 11 | and both real and imaginary impedances with low mean absolute percentage errors of 4.9%, 7.5%, and 7.7%, respectively, demonstrating the model's ability to accurately predict the antenna's performance. [ABSTRACT FROM AUTHOR]

This study examines the holographic representation of the quantum theory of transmission lines, which play a crucial role in quantum computing and quantum information. By utilizing Yurke and Denker's quantum circuit network theory within the framework of continuous Multi-scale Entanglement Renormalization Ansatz (cMERA) in AdS space, we analyze the quantization and interactions of transmission lines. The metric is revealed to be described by the inductance of the quantum circuit, which is AdS space in its 0-limit. These results provide new insights into handling and controlling complex phenomena in quantum circuits, potentially advancing the understanding of quantum computing and quantum communication. [ABSTRACT FROM AUTHOR]

A design for manufacturing (DFM) of a well‐performing wideband coaxial filter line using direct metal laser sintering (DMLS) additive manufacturing is proposed. The demonstrated transmission line is an air‐filled coaxial line chosen for low loss and consistent group delay over the bandwidth. Transmission line theory is used first to account for the impact of the shorted stub needed to support the central conductor. Deviations due to parasitics are described to transition the design from an ideal model to a physical prototype. The constraints inherent in DMLS are discussed and accounted for throughout the DFM. This process is demonstrated with a prototype having return and insertion losses of greater than 10 dB and less than 1.64 dB, respectively, over a 5.3:1 bandwidth from 6.4 to 33.9 GHz with a flat group delay of 129 ps ± 7%. [ABSTRACT FROM AUTHOR]

Implementation of reconfigurable metasurfaces demands a complex structure. The design methodology for metasurface elements based on PIN diodes requires targeted optimisation tailored to the varying application environments and cannot be directly transplanted from one methodological approach to another. In addition, inclusion of varactors often imposes undesirable high‐power consumption with complex analog drive circuitry. Furthermore, the design method for the reconfigurable metasurface element has not been simplified and unified, hindering the rapid deployment of metasurface applications. The authors propose a general design model based on low‐power embedded circuitry for a multi‐function metasurface element and give the corresponding numerical analysis. The authors present a reconfigurable method based on the general design model and prove that the method achieves independent regulation of amplitude and phase for the reflected electromagnetic wave. Through analysis of the sensitive area at the bottom of the embedded circuit, a gradient descent algorithm is proposed to find the optimised phase points according to device sensitivity of the application scenario and suitable strategy. Finally, the authors demonstrate that the designed metasurface element possesses phase control capability and decent phase consistency obtained via far‐field scanning experiments. The proposed element design method will provide a theoretical reference for the integrated design of metasurface. [ABSTRACT FROM AUTHOR]

A wideband Magneto‐Electric Dipole (MED) antenna with high gain is proposed for the 700/800/850/900 MHz frequency bands for cellular network applications. The antenna comprises a half‐wavelength bow‐tie‐shaped dipole, an elongated magnetic loop and a ground reflector with four Elevated Ground Planes (EGPs) at reflector's corners. The EGPs enhance the antenna gain and Front‐to‐Back Ratio (FBR), which is a promising technique in the MED antenna design. The antenna is excited by a Γ ${\Gamma }$‐shaped coupling element. An analytical model of the proposed antenna is developed by employing Schelkunoff's model for dipole antennas and the transmission line theory complemented by radiation resistance corrections. The antenna design is validated with full‐wave numerical simulations. The antenna is fabricated using cut and bent metallic plates and tested in an anechoic chamber. The analytical, numerical and experimental results are in a good agreement. The experimental results confirm that the proposed MED antenna with dimensions of 1.44λ×1.44λ×0.27λ $1.44\lambda \times 1.44\lambda \times 0.27\lambda $ achieves a bandwidth of 61.53% (623.1–1176.8 MHz) for VSWR<1.5 $VSWR< 1.5$ and a stable gain of 9.8 ± $\pm $ 1.9 dBi. By employing the EGPs, the realized peak gain and FBR are enhanced by 0.52 dBi and 1.1 dB, respectively. Plain Language Summary: This study presents a novel Magneto‐Electric Dipole (MED) antenna design with improved bandwidth and gain characteristics tailored for the cellular network access across several frequency bands. As a distinctive feature, this MED antenna includes a ground reflector with Elevated Ground Planes (EGPs) at its corners to enhance its gain and Front‐to‐Back Ratio (FBR). Additionally, in this work we propose a new equivalent circuit for MED antennas based on the Schelkunoff's model for electric dipoles and the transmission line theory improved by radiation corrections. The performance of the MED antenna and the developed models are validated through numerical simulations and experimental testing. This research showcases advancements in MED antenna modeling and design aimed at increased performance and capacity of cellular networks. Key Points: Development of an analytical model for the proposed antenna using Schelkunoff's model for dipole antennas and transmission line theoryEGPs are utilized to enhance antenna gain and FBR, representing a promising technique in MED antenna design [ABSTRACT FROM AUTHOR]

In recent years, machine learning (ML) and deep learning (DL) have been widely used to break the metasurface’s performance ceiling. However, the existing data‐driven ML and DL methods usually require the availability of vast amounts of training data to ensure their stable and accurate performance. The process of acquiring these data is high‐cost due to the need for numerous full‐wave electromagnetic (EM) simulations. Here, we  propose a low‐cost surrogate model to generate these data efficiently. The proposed model employs microwave network theory to separate meta‐elements into four independent components. Through integration with transmission line theory, we  derive the EM responses of meta‐elements using analytical representation with the active device equivalent impedance and dielectric as design variables. Two typical phase‐modulation active meta‐elements are employed to verify the accuracy of our  macromodel in comparison with full‐wave EM simulations. Based on the developed macromodel, the superior prediction ability is further presented to illustrate the performance of meta‐elements with various active devices and dielectric substrates. The proposed macromodel is a feasible and general method to rapidly obtain the necessary training data of active meta‐elements, which holds a great potential to significantly reduce the designing time of ML and DL models for the active metasurfaces. [ABSTRACT FROM AUTHOR]

In this article, a set of equations is derived to find incident and load power explicitly in terms of load and source reflection coefficients in a lossless transmission line mismatched to both source and load impedances. A transmission line can be mismatched as the frequency varies if the source and load impedances are frequency dependent. Unlike in a scenario, where the transmission line is either matched to the source or load, the incident and load power depends on the length of the transmission line when both the source and load impedances are not matched to the line. The equations derived show that the power varies with the line length with a period of half wavelength. The maximum and minimum incident and load power with the corresponding line lengths are derived. The use of the Smith chart to find these lengths and the ratio of maximum to minimum is also described. Finally, three applications of the results including an additional version of the Friis transmission equation and the bandwidth improvement of power transfer for frequency dependent source and load impedances are presented. [ABSTRACT FROM AUTHOR]

Plasmonic nanoantennas with suitable far-field characteristics are of huge interest for utilization in optical wireless links, inter-/intrachip communications, LiDARs, and photonic integrated circuits due to their exceptional modal confinement. Despite its success in shaping robust antenna design theories in radio frequency and millimeter-wave regimes, conventional transmission line theory finds its validity diminished in the optical frequencies, leading to a noticeable void in a generalized theory for antenna design in the optical domain. By utilizing neural networks, and through a one-time training of the network, one can transform the plasmonic nanoantennas design into an automated, data-driven task. In this work, we have developed a multi-head deep convolutional neural network serving as an efficient inverse-design framework for plasmonic patch nanoantennas. Our framework is designed with the main goal of determining the optimal geometries of nanoantennas to achieve the desired (inquired by the designer) S11 and radiation pattern simultaneously. The proposed approach preserves the one-to-many mappings, enabling us to generate diverse designs. In addition, apart from the primary fabrication limitations that were considered while generating the dataset, further design and fabrication constraints can also be applied after the training process. In addition to possessing an exceptionally rapid surrogate solver capable of predicting S11 and radiation patterns throughout the entire design frequency spectrum, we are introducing what we believe to be the pioneering inverse design network. This network enables the creation of efficient plasmonic antennas while concurrently accommodating customizable queries for both S11 and radiation patterns, achieving remarkable accuracy within a single network framework. Our framework is capable of designing a wide range of devices, including single band, dual band, and broadband antennas, with directivities and radiation efficiencies reaching 11.07 dBi and 75 %, respectively, for a single patch. The proposed approach has been developed as a transformative shift in the inverse design of photonics components, with its impact extending beyond antenna design, opening a new paradigm toward real-time design of application-specific nanophotonic devices. [ABSTRACT FROM AUTHOR]

Manipulating electromagnetic (EM) waves by plasma-dielectric-plasma (PDP) waveguides or plasma array structures presents significant potential in microwave signal processing, such as filtering, signal delay, and EM enhancement or shielding. Owing to the simple structure and easy fabrication, the waveguide with a tooth-shaped resonator has been a strong candidate as a filtering device. Based on our previous work focusing on U-shaped filtering excited by PDP waveguides with a double-teeth structure, in this work, the formation mechanism of a U-shape filtering spectrum is systematically explored by transmission line theory (TLT) with proper field distributions. The results indicate that the U-shape spectrum consists of boundary edges and a filtering stopband. The boundary edges are attributed to Fano-type resonance, and the enhanced destructive interference from double teeth is responsible for the stopband. Such an approach shows a specific and clear mechanism for the generated U-shaped spectrum. In addition, the theoretical analysis of double teeth without Fano-type resonances is rigorously demonstrated using TLT, which significantly contributes to bandwidth modulation of stopband filtering in theory. These results contribute to the understanding of the formation mechanism of a U-shaped spectrum from a gap plasmon waveguide (such as PDP or metal-insulator-metal (MIM)) with tooth-shaped resonators, offering a feasible direction for the optimization of filtering properties, as well as offering significant parameters for subsequent experimental design. [ABSTRACT FROM AUTHOR]

In this letter, a multilayer dielectric with a lossy frequency-selective surface (FSS) absorber is proposed, which is composed of three layers of resistive film-dielectric composite layer and a metal grounded plane. Particularly, each resistive film-dielectric composite layer consists of a polyethylene terephthalate (PET), polymethacrylimide foam (PMI), and resistive film layer. An equivalent circuit model is established to further understand the performance of the absorber based on the impedance matching approach and the transmission line theory. Experimental results reveal that the metamaterial absorber (MMA) covers -10 dB bandwidth of 1.96-21.8 GHz for normal incidence. Meanwhile, the absorption rate can retain more than 80% for both TE and TM polarizations within 55° incidence angles. Furthermore, the fractional bandwidth of the MMA is 167% and its thickness is only 0.108 ?L. The MMA has the characteristics of ultra-wideband, high absorption rate, and polarization stability, making it suitable for communication systems. [ABSTRACT FROM AUTHOR]

LaNiO 3 is considered electromagnetic wave-absorbing material owing to its unique crystal structure and controllable dielectric constant. However, the effect of ion doping modification on microwave absorption performance remains to be thoroughly investigated. In this study, LaNi 1− x Ba x O 3 (x = 0, 0.02, 0.04, 0.06) was prepared through sol-gel methods. The reflection loss (RL) of the sample in the 2−18 GHz band was calculated using transmission line theory. Specifically, LaNi 0.96 Ba 0.04 O 3 exhibited superior results, with an RL value of −34.54 dB at d = 3 mm and f = 6.80 GHz, indicating effective absorption within the C-band. These results suggest that adding an appropriate amount of Ba ions to the material can effectively regulate the electromagnetic parameters and optimize impedance matching. Introducing Ba ions into the crystal interior produces abundant defects, which provide active sites for multipolarization and ultimately improve the wave-absorbing properties of the material. In addition, radar cross section(RCS) simulations simulation after coating the samples on original ideal conductor (PEC) substrates provide support for potential practical applications of the material. [ABSTRACT FROM AUTHOR]

In this paper, a multifunctional terahertz (THz) metamaterial device with multifunction is proposed. Based on graphene and vanadium dioxide (VO2), tunable broadband absorption and transmission characteristics are realized. While VO2 is in the metallic phase, the device works in ultra-broadband absorption mode. The bandwidth of over 90% absorption is 5.36 THz, corresponding to a relative bandwidth of 90%. By adjusting the Fermi level of graphene, we can obtain a bandwidth modulation depth of 54%. By changing the conductivity of VO2, we can achieve an amplitude modulation depth of 87%. While VO2 is in the insulated phase, the device works in transmission mode. The frequency range of over 90% transmissivity is 5.00–7.15 THz. Similarly, by adjusting VO2 conductivity, an amplitude modulation depth of 96% can be achieved. Based on transmission line theory, an equivalent circuit is established to reveal the modulation mechanism. Theoretical results are in good agreement with the ones got from simulation. Compared with the papers previously published, the structure has certain advantages on function switching, performance tuning, and modulation depth. [ABSTRACT FROM AUTHOR]

The current research introduces a multilayer functional structure along with its corresponding multi-objective optimization design strategy intended to improve the design efficiency of materials exhibiting remarkable properties in both load-bearing and electromagnetic wave absorption. The composite structure contains several layers of graphite oxide reinforced epoxy resin, each of which has a different thickness and volume fraction of fillers. The proposed strategy employs the volume fraction of fillers and thickness of each layer as the design variables, with the electromagnetic wave absorption bandwidth and bending stiffness of the entire structure serving as objectives. The multi-objective model was derived using the Maxwell-Garnett Model, Halpin-Tsai Model, Transmission Line Theory and Classical Laminate Theory. To efficiently optimize the multilayer structure, the JAYA, an evolutionary algorithm is employed as optimizer. The results indicate that the optimized structure exhibits a considerable increase in electromagnetic wave absorbing capacity and a slight increase in load-bearing performance relative to the original structure, while the total thickness remains constant. In addition, the whole process takes only a few seconds. [ABSTRACT FROM AUTHOR]

Abstract Power flow, planning, economics, dispatch, and stability analysis rely on accurate transmission line parameters (TLPE). Standard optimization methods are employed to develop such analyses and obtain TLPE. Additionally, these methods have limitations, including precision, accuracy, and time complexity. It is challenging to find improved solutions using standard optimization methods due to slow convergence and limitations in identifying local optima. Concerned with these challenges, the study suggest a new application for an effective hybrid optimization method capable of addressing such limitations. The hybrid algorithm, named the Salp Swarm Algorithm with Sine Cosine Algorithm (HSSASCA), that aims to tackle the issues of slow convergence and local optima. The Sine Cosine Algorithm (SCA) is employed after the Salp Swarm Algorithm (SSA), and Salp integration is utilized to successfully explore and analyze the search space. To enhance the performance of HSSASCA, the hybrid technique aims to provide expanded exploration capabilities, effective exploitation of the search space, and a better convergence rate. These key features position the HSSASCA algorithm as an effective solution to complex optimization problems. To assess the efficiency of the HSSASCA algorithm, six different test systems are employed. Initially, the evaluation of exploration, exploitation, and minimized local optima is conducted using the CEC 2019 benchmark functions. Secondly, efficiency monitoring and verification of HSSASCA across different scenarios occur by comparing it with established optimization algorithms such as SSA, SCA, firefly optimization algorithm (FFO), Grey Wolf Optimization (GWO), student psychology‐based optimization (SPBO), and Symbiotic Organisms Search (SOS). Finally, statistical analysis is performed, revealing that the HSSASCA outperforms SSA, SCA, FFO, GWO, SPBO, and SOS. In terms of statistical results and convergence curves, the HSSASCA demonstrates superior performance in searching efficiency, convergence accuracy, and local optimum avoidance ability.

A simple equivalent circuit model (ECM) for a reflective polarization converter (RPC) comprising anisotropic metasurfaces is presented in this paper. The impedance matrix of an anisotropic metasurface in x and y axis is derived by the impedance matrix in a diagonal axis multiply with a rotated matrix, while the diagonal impedance matrix can be calculated by a simple L C network, which contains a series of capacitors and inductors. The presence of the dielectric substrates is considered using the transmission line theory. Some typical RPCs with different metasurface shapes are used to verify the effectiveness of the ECM. The methodology provides a simple approach for the design and optimization of RPC. Finally, we designed a polarization converter based on the proposed method, and the measured results are in good agreement with the theoretical results. [ABSTRACT FROM AUTHOR]

The coupling of electromagnetic pulse (EMP) with the star‐quad cable having reference conductor is analyzed by using the proposed model, which is based upon multi‐conductor transmission line theory. Expressions for common‐mode (CM) and differential‐mode (DM) currents are developed. Two cases are mainly discussed: the first case is the star‐quad cable with a central reference conductor, and the second case with the outside reference conductor. A rigorous comparison between these two cases shows that when the reference conductor is placed at the center, the magnitude of CM current is reduced dramatically, which is beneficial for electromagnetic compatibility (EMC). The CM current magnitude of the outside reference conductor is relatively very high due to the large CM current loop area, which is the least possible for the central reference conductor. There is no significant change in the DM current magnitude for both cases because the DM current has no direct dependence on the CM current loop area. A commercial software, FEKO, which utilizes the method of momentum (MoM), is used to compare the results of our proposed method, which are in good agreement. [ABSTRACT FROM AUTHOR]

The equivalent wave impedance circuit model (ECM-WI) is presented for the analysis of frequency selective surfaces (FSS). The development of the analytical model is based on homogenization theory, as well as analogies between wave theory and transmission line theory. The coplanar strip model and the concept of wave impedance are used to scale the Marcuvitz model for periodic strip gratings of conductive strips, as well as to consider the influence of the presence of a lossy dielectric substrate on the frequency response of the FSS. In particular, the model is applied to the analysis of square loop FSSs and considering the normal incidence. The results obtained are presented by comparing full-wave simulations for the two proposed models, obtaining average deviations in absolute values (%) of 2.11 and 0.38 for resonance frequency and 3.45 and 5.49 for bandwidth. The prototype manufactured in FR-4 obtained a deviation of 2.56% for resonance frequency and 2.79% for bandwidth. [ABSTRACT FROM AUTHOR]

Power flow, planning, economics, dispatch, and stability analysis rely on accurate transmission line parameters (TLPE). Standard optimization methods are employed to develop such analyses and obtain TLPE. Additionally, these methods have limitations, including precision, accuracy, and time complexity. It is challenging to find improved solutions using standard optimization methods due to slow convergence and limitations in identifying local optima. Concerned with these challenges, the study suggest a new application for an effective hybrid optimization method capable of addressing such limitations. The hybrid algorithm, named the Salp Swarm Algorithm with Sine Cosine Algorithm (HSSASCA), that aims to tackle the issues of slow convergence and local optima. The Sine Cosine Algorithm (SCA) is employed after the Salp Swarm Algorithm (SSA), and Salp integration is utilized to successfully explore and analyze the search space. To enhance the performance of HSSASCA, the hybrid technique aims to provide expanded exploration capabilities, effective exploitation of the search space, and a better convergence rate. These key features position the HSSASCA algorithm as an effective solution to complex optimization problems. To assess the efficiency of the HSSASCA algorithm, six different test systems are employed. Initially, the evaluation of exploration, exploitation, and minimized local optima is conducted using the CEC 2019 benchmark functions. Secondly, efficiency monitoring and verification of HSSASCA across different scenarios occur by comparing it with established optimization algorithms such as SSA, SCA, firefly optimization algorithm (FFO), Grey Wolf Optimization (GWO), student psychology‐based optimization (SPBO), and Symbiotic Organisms Search (SOS). Finally, statistical analysis is performed, revealing that the HSSASCA outperforms SSA, SCA, FFO, GWO, SPBO, and SOS. In terms of statistical results and convergence curves, the HSSASCA demonstrates superior performance in searching efficiency, convergence accuracy, and local optimum avoidance ability. [ABSTRACT FROM AUTHOR]

Featured Application: The focus of this paper is on the design of the RF (Radio Frequency) resonant cavities required for small modular superconducting cyclotrons. The design of these RF cavities aims to match the smaller extraction radius of superconducting cyclotrons and make easier of installation and maintenance. To this purpose, one has to adopt a design that allows for easy assembly and disassembly with the magnet system that has been adopted. Through the study of the circuitry of such RF cavities, along with calculations of electromagnetic fields and methods of frequency tuning, we provide a set of solutions that can serve as a reference for the design of smaller superconducting accelerators in the future. This not only helps in advancing the technology of superconducting cyclotrons but also can provide a method reference for related technical fields. In contrast to the room temperature cyclotron, the superconducting cyclotron's high operational magnetic field and small extraction radius lead to a magnet design with a reduced radius. This limits the space available for the RF cavity in the 11 MeV superconducting cyclotron, necessitating a more compact RF cavity design. By using the transmission line theory, the complex structure of the quarter-wavelength coaxial cavity can be represented as a microwave circuit. Through relevant theoretical analytical formulas, equivalent circuit parameters can be derived. The resonant frequency of the RF cavity is then determined using the equivalent circuit method. The optimization of the RF cavity structure was achieved by creating a numerical model and conducting finite element numerical calculations on the high-frequency resonant system. The comparative results between the equivalent circuit and numerical calculations indicate that the frequency error remains within 0.1%, validating the compact RF cavity design. A multiple linear regression analysis facilitates the prediction of resonance frequency across various parameter variables. By analyzing the fitting formula, RF cavity machining error requirements are established, ensuring a prediction error within 1%, thus meeting engineering design criteria. [ABSTRACT FROM AUTHOR]

This paper presents a model, design, and implementation of a metasurface electromagnetic (EM) wave absorber for operation in the frequency range of the X-band. The model of the metasurface was constructed with a split ring resonator (SSR) and a stripline and it was designed with a single unit cell, whereby the results were approached with transmission line theory for patch impedance extraction. Implementation of a metasurface EM wave absorber was deployed on an FR4 Epoxy dielectric substrate with dimensions of 80-unit cells x 80-unit cells and characterized with two horn antennas, which were connected to a signal generator as the transmitter and a spectrum analyzer as the receiver. In front of the horn antennas a device under test (DUT) was installed, i.e., a metasurface EM wave absorber and a metal plate with similar dimensions. The metal plate was expected to perform full reflection at the same distance and antenna orientation. The same condition was used as a normalization factor to optimize the absorption of the metasurface EM wave absorber. The characterization results showed that the minimum normalized absorption of the SRR and stripline at the designated measurement distances was 0.99, 0.99, 0.99, and 0.97, at frequencies of 8.85 GHz, 9.08 GHz, 9.15 GHz, and 9.10 GHz, respectively, and a 0° antenna orientation. [ABSTRACT FROM AUTHOR]

This research paper presents a compact dual-band polyester-based wearable bandpass microstrip filter using stepped impedance resonator. In the proposed wearable filter, pass band of 1.85 GHz to 2.66 GHz is useful for ISM band and 3.74 GHz to 7.42 GHz is appropriate to Wi-Fi, WLAN and Wi-Max frequency band applications respectively. In this filter, insertion loss of 0.147 dB and return loss of 32.6 dB at 2.38 GHz insertion loss of 0.469 dB and return loss of 32.3 dB at 4.54 GHz with fractional bandwidth of 34% and 81% is respectively achieved. The proposed wearable filter is fabricated using polyester cloth substrate and selfadhesive copper tape. The Agilent vector network analyzer is used to test the fabricated polyester filter. Good agreement is obtained between the simulated as well as measured insertion loss and return loss of the proposed wearable filter. Equivalent circuit and SAR analysis of this filter is also presented in this paper. Novelty of this research paper is fabrication of high bandwidth dual band wearable filter that can be integrated with wearable antenna to be a wearable Filtenna. Modified equivalent circuit of SIR is prepared and validated. Simulated and measured results are found to be in good agreement. [ABSTRACT FROM AUTHOR]

Impedance matching theory is commonly used within the field of microwave absorption theory though extensive research published recently has shed light on the inherent flaws in this well-established theory. Many distinct definitions have been developed for the theory, among them are impedance matching coefficients for interfaces and films. The current study provides compelling evidence that the shortcomings identified within impedance matching theory also extend to these coefficients. These findings underscore that the application of a quarter-wavelength impedance converter in transmission line theory fundamentally departs from the principles underlying quarter-wavelength and impedance matching theories concerned with microwave absorption. The flaws in impedance matching theory are further emphasized in this study. [ABSTRACT FROM AUTHOR]

Based on transmission line theory, a 4‐way wideband coupled‐line Wilkinson power divider is designed by the authors, operating from 6 to 18 GHz. It is established by using a novel manufacturing technology with 3D stacked micro‐coaxial line, realising attractive advantages of low insertion (IL) loss and compact size. The simulated result shows that the proposed power divider of 23.5 × 14.46 × 0.9 mm obtains a maximum IL of 0.42 dB over the entire operating band. Measured results are obtained by connecting this micro‐coaxial power divider with printed circuit board, showing that the proposed structure is suitable for microwave communication systems. [ABSTRACT FROM AUTHOR]

This paper presents an ultra-wideband transformer feedback (TFB) monolithic microwave integrated circuit (MMIC) power amplifier (PA) developed using a 0.25 μm gallium nitride (GaN) process. To broaden the bandwidth, a drain-to-gate TFB technique is employed in this PA design, achieving a 117% relative −3 dB bandwidth, extending from 5.4 GHz to 20.3 GHz. At a 28 V supply, the designed PA circuit achieves an output power of 25.5 dBm and a 14 dB small-signal gain in the frequency range of 6 to 19 GHz. Within the 6 to 19 GHz frequency range, the small-signal gain exhibits a flatness of less than 0.78 dB. The PA chip occupies an area of 1.571 mm2. This work is the first to design a power amplifier with on-chip transformer feedback in a compound semiconductor MMIC process, and it enables the use of the widest bandwidth power amplifier on-chip transformer matching network. [ABSTRACT FROM AUTHOR]

The field of P-band (0.3–1 GHz) absorption has witnessed rapid development in metamaterial absorbers due to their exceptional designability and the absence of restrictions imposed by the one-fourth wavelength rule. In this study, we combined carbonyl iron powder (CIP) composites with a periodic structure composed of metal capacitive patterns and employed a genetic algorithm (GA) to optimize the electromagnetic parameters of the CIP substrate. By selecting the appropriate shape and material for the units of pattern based on transmission line theory, as well as regulating relevant structural parameters, we successfully designed an ultra-thin broadband metamaterial absorber for the P-band. Experimental results demonstrate that within the range of 0.3–0.85 GHz, the reflection loss of our absorber remains below −5 dB, with a maximum value of −9.54 dB occurring at 0.45 GHz. Remarkably, this absorber possesses a thickness equivalent to only 1/293 of its working wavelength. Then, we conducted analyses on electric field distribution, magnetic field distribution, and energy loss density. Our findings suggest that high-performance absorption in metamaterials can be attributed to λ/4 resonant or coupling effects between structural units or diffraction phenomena. This absorber offers several advantages, including broad low-frequency absorption capability, ultra-thin profile, and convenient fabrication process, thus providing valuable theoretical insights for designing metamaterial structures. [ABSTRACT FROM AUTHOR]

This study developed a method for interconverting voltage, current, and power sources used in electromagnetic (EM) simulations. By incorporating voltage and current waves, equations for power, voltage, and current were derived while accounting for the presence or absence of transmission lines between the source and load. In particular, in the absence of a transmission line between the source and load, the characteristic impedance of the transmission line appears in these equations. To elucidate this observation, the equations for voltage, current, and power were analyzed, and mutual conversion equations based on voltage and current waves were formulated. Additionally, the interconversion equations based on voltage and current waves were applied to a three-dimensional (3D) EM simulation, and they were validated by comparing the simulation results for each equivalent source. [ABSTRACT FROM AUTHOR]

Manipulating electromagnetic (EM) waves by plasma–dielectric–plasma (PDP) waveguides or plasma array structures presents significant potential in microwave signal processing, such as filtering, signal delay, and EM enhancement or shielding. Owing to the simple structure and easy fabrication, the waveguide with a tooth-shaped resonator has been a strong candidate as a filtering device. Based on our previous work focusing on U-shaped filtering excited by PDP waveguides with a double-teeth structure, in this work, the formation mechanism of a U-shape filtering spectrum is systematically explored by transmission line theory (TLT) with proper field distributions. The results indicate that the U-shape spectrum consists of boundary edges and a filtering stopband. The boundary edges are attributed to Fano-type resonance, and the enhanced destructive interference from double teeth is responsible for the stopband. Such an approach shows a specific and clear mechanism for the generated U-shaped spectrum. In addition, the theoretical analysis of double teeth without Fano-type resonances is rigorously demonstrated using TLT, which significantly contributes to bandwidth modulation of stopband filtering in theory. These results contribute to the understanding of the formation mechanism of a U-shaped spectrum from a gap plasmon waveguide (such as PDP or metal–insulator–metal (MIM)) with tooth-shaped resonators, offering a feasible direction for the optimization of filtering properties, as well as offering significant parameters for subsequent experimental design.

Examining cables using the many conductor transmission line theory has shed light on the modes supported by various cable types. However, so far, the theory disregards the fundamental surface wave mode whose lateral confinement increases with frequency and hence is expected to play an important role in high-frequency applications. To address this issue, we propose an extension to the theory that incorporates surface waves on uncoated, cylindrical wires. Crucially, this requires new definitions of the per unit length transmission line parameters, which are derived using the single wire surface wave solution. By closely examining a two-wire and a three-wire system, we show that these new parameters can predict surface waves as well as modes found using conventional many conductor transmission line theory. Furthermore, all calculated modes are validated experimentally by diagonalization of a measured coupling matrix. Additionally, the propagation constants for the modes predicted by the model are validated against full numerical simulations. Good agreement is observed when proximity effects can be neglected. [ABSTRACT FROM AUTHOR]

With increasing concerns regarding the potential health risks associated with microwave‐based technology, researchers have been actively investigating materials with impressive microwave absorption properties. In this study, a synthesis and investigation of a nanocomposite, named Fe3O4/MWCNT/ZnO/PANI, consisting of magnetite (Fe3O4), multi‐walled carbon nanotube (MWCNT), zinc oxide (ZnO), and polyaniline (PANI) as a microwave‐absorbing material, was carried out for the first time. The nanocomposite was prepared through a simple physical mixing approach and demonstrated tunable microwave absorption, making it highly suitable for shielding applications. Structural analysis techniques, including X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy‐dispersive X‐ray analysis (SEM‐EDAX), confirmed the presence of all components in the nanocomposite. Moreover, ultraviolet‐visible spectroscopy (UV‐Vis) further verified the formation of nanocomposite components and revealed an adjustable optical bandgap ranging from 2.86 to 3.34 eV. Impressively, the nanocomposite exhibited promising microwave absorption properties, with a minimum reflection loss (RL) of −32.66 dB for the nanocomposite containing 37.50 % PANI by weight, and a maximum electromagnetic bandwidth (EB) of 2.26 GHz for the nanocomposite containing 44.44 % PANI by weight, indicating its potential as an effective shielding material. Furthermore, a modified theory combining transmission line, Landau‐Lifshits, and Drude‐Lorentz theories was introduced to extract complex relative permittivity and permeability, providing insights into the role of polyaniline in enhancing the microwave absorption properties of the nanocomposite as measured by reflection loss (RL). [ABSTRACT FROM AUTHOR]

In the present article, a design approach to accomplish circular polarization-based rhombus ring microstrip-fed monopole antenna working at 5.8 GHz for wireless body area network (WBAN) applications is proposed. The input impedance calculation using an electromagnetic theory of transmission line in a travelling wave coupled to the parallel-plate inductor model is conducted. Radiated electric field pattern calculation of the conventional square ring microstrip patch antenna (MSPA) using Biot and Savart's law is reported. The circular polarization of the proposed antenna is accomplished by loading the radiating path with a capacitive element sectioned in the neighbourhood of the feed line. The proposed planar monopole antenna of volume 0.38 λ 0 × 0.38 λ 0 × 0.029 λ 0 ( λ 0 is evaluated at the resonant frequency of 5.8 GHz) achieves a -10 dB impedance bandwidth of 86.20% in the band (3-8 GHz) with a stable real gain of 8.29 dBic in circular polarization at the resonant frequency of 5.8 GHz and axial ration bandwidth of about 32.75% in the (5-6.9 GHz) band. Specific absorption rate (SAR) evaluation of the studied antenna is computed numerically on a part of the human phantom model to justify its use in WBAN applications. It is noted that the maximum amount of radiation absorbed by a part of the human phantom model is limited to a maximum SAR value of 1.45 W/kg and 0.754 W/kg on 1 g and 10 g of tissue mass, respectively. The prospective design has been fabricated and tested, and the experimental results are in good agreement with the simulation outcomes. [ABSTRACT FROM AUTHOR]

Microwave power absorption by a two‐layer system deposited on a metallic surface is studied in the experimental setup emulating the response to a radar signal. Layers containing hexaferrite and iron powder in a dried paint of thickness under 1 mm are used. The data is analyzed within a theoretical model derived for a bilayer system from the transmission line theory. A good agreement between experimental and theoretical results is found. The advantage of using a bilayer system over a single‐layer system is demonstrated. How the maximum microwave absorption (minimum reflection) can be achieved through the optimization of the filling factors and thicknesses of the two layers is shown. [ABSTRACT FROM AUTHOR]

A simple and compact three-way planar power divider, which avoids the floating common node of the isolation resistors, is presented. The proposed structure exhibits a wideband operation (measured frequency range of 1.6–3.3 GHz and bandwidth of 69.4%) with good return loss and isolation characteristics. Transmission line theory is used for the mathematical analysis and extraction of design equations, followed by simulations and experimental measurements that confirm the predicted results. The proposed divider achieves an equal power split (∼32%, −4.9 ± 0.4 dB insertion loss) between the input and each output port. The measured return loss is better than −10 dB at all ports, and the measured maximum isolation is close to −30 dB. The proposed design exhibits a fully planar structure, thus eliminating the need for a floating common node for the isolation resistors. Additionally, its structure is much simpler (i.e., no coupled lines, crossovers, or lumped capacitors are required) than other designs, achieves wideband operation, and provides design simplicity, flexibility, and easy implementation. Despite its simple noncomplicated structure, the proposed three-way planar divider achieves similar (or in some cases, better) performance and size than other more complicated structures. Furthermore, it can be expanded to an n -way structure. [ABSTRACT FROM AUTHOR]

In this paper, a broadband, polarization-independent metamaterial absorber for millimeter waves is proposed. Operating across the frequency range of 22.7 GHz to 37.2 GHz, our broadband, polarization-independent absorber demonstrates exceptional efficacy by capturing over 90% of incident wave power. Distinguished by an array of conductive square patches on a dielectric substrate, the proposed structure boasts a remarkably low thickness, measuring less than a quarter of the free space wavelength of the central point within its operational spectrum (excluding the ground layer thickness). Leveraging a combination of circuit modeling and transmission line theory, this paper presents the design of this absorber and also elucidates its underlying operating principles. The combination of broadband operation, low thickness, and systematic design is rarely seen in previous works. To validate the proposed approach, a physical prototype is realized using 3D printing technology, employing conductive polylactic acid (C-PLA) patches on a light polyvinyl chloride (L-PVC) substrate. The proposed absorber has various potential applications in communication, electromagnetic shielding, and satellite technologies. Finally, a comparison with recent works is performed to demonstrate the feasibility of the proposed structure for millimeter-wave applications. [ABSTRACT FROM AUTHOR]

Impedance matching networks using lumped inductors and capacitors are only applicable at lower radio frequencies (RF). At high microwave frequencies, transmission lines should be used in matching network design, but the required substrate area may be too large. This paper presents a dual-section matching network design method that uses the shortest possible transmission lines. It is particularly advantageous for radio frequency integrated circuit (RFIC) design. Both single- and dual-section solutions are presented with detailed equations and design methodologies. The methods are flexible enough to accommodate the modification of the line width to an attainable value, with a trade-off of a slight increase in the overall transmission line length. The Q-factor and bandwidth can be adjusted to suit different application needs by modifying the line width and length. A few design examples are presented herein. [ABSTRACT FROM AUTHOR]

The perovskite manganese oxide, La 0.7 Sr 0.3 Mn 1+ x O 3 (x = −0.4, −0.2, 0, 0.2, 0.4, 0.6, 0.8, 1.0), was synthesized using the solid-state reaction method. A single-phase perovskite structure was obtained at the stoichiometric composition (x = 0). However, with an increase in Mn excess (x > 0), secondary phases of Mn 2 O 3 and Mn 3 O 4 formed and increased, while La 2 O 3 and Sr-rich phases emerged when Mn is deficient (x < 0). The electrical conductivity, permittivity, and permeability of the samples showed significant variations with x , as both charge transport and magnetism originate from the presence of Mn. Complex permittivity (ε', ε") and permeability (μ', μ") spectra were utilized to calculate RL maps based on a transmission line theory. For samples with x ≥ 0, which exhibited relatively high values of ε' and ε", there was no significant absorption of electromagnetic (EM) waves within the measured frequency range (0.1 ≤ f ≤ 18 GHz) due to high EM wave reflection. Conversely, the Mn-deficient samples (x = −0.2, −0.4) demonstrated excellent EM wave absorption properties in the GHz range. This can be attributed to their favorable impedance matching characteristics, resulting from significantly reduced ε' and ε" values in the Mn-deficient samples. Notably, the sample with x = −0.2 exhibited the most outstanding EM wave absorption characteristics, with an RL value of −56 dB at a frequency of 2.33 GHz and a thickness of 7.59 mm. Additionally, it achieved an RL value of −50 dB at 9.8 GHz and 2.90 mm thickness. [ABSTRACT FROM AUTHOR]

Fano resonance arises from the superposition of a narrow discrete resonance with a continuous state. In this paper, a Fano resonance‐based plasmonic refractive index sensor based on nanoscale metal‐insulator‐metal (MIM) waveguides is proposed and evaluated by applying the two‐dimensional finite‐difference time‐domain (2D FDTD) method. An MIM‐based single stub vertically attached to an MIM waveguide is considered as the unit cell of the waveguide system of the proposed structure. A transfer matrix of transmission and coupling complex coefficients is defined for the unit cell of the waveguide system of the proposed sensor, and the conditions for the authenticity of its modeling based on the transmission line theory are evaluated. A system of triplet coupled stub resonators (TCSRs) attached to an MIM waveguide is coupled with a disk resonator to induce Fano resonances in the transmission spectrum of the sensor. Fano resonance and its characteristics are utilized to improve the essential operating parameters of the sensor, such as full width at half maximum (FWHM) and figure of merit (FOM). In optimized conditions, for the system of TCSRs coupled to a disk resonator, a resonance with a sensitivity of 684 nm/RIU and an FOM of 621.8 1/RIU exhibited. Also, for the system of TCSRs coupled to a ring resonator, a resonance with a sensitivity of 3524 nm/RIU and an FOM of 35.24 1/RIU was achieved. Eventually, the numerically achieved results for the operating parameters of the sensor are validated using governing analytical methods. [ABSTRACT FROM AUTHOR]

Electronic toll collection (ETC), known as a non-stop toll collection system which can automatically realize payment by setting the identification antenna at the entrance, is always suffering from information exchange interruption caused by beam switching. A circularly polarized sector beam antenna array operating at 5.8 GHz with flat-top coverage is proposed, based on the weighted constrained method of the maximum power transmission efficiency (WCMMPTE). By setting the test receiving antennas at the specific angles of the ETC antenna array to be designed, constraints on the received power are introduced to control the radiation pattern and obtain the optimized distribution of excitations for antenna elements. A 1-to-16 feeding network, based on the microstrip transmission line theory is designed to feed a 4 × 4 antenna array. Simulation results show that the half-power beamwidth covers an angular range of −30° to 30° while the axial ratio is below 3dB, which meets the ETC requirements. Furthermore, the gain fluctuation among the needed range of −30° to 30° is lower than 0.7 dB, which is suitable for the ETC system to achieve a stable signal strength and uninterrupted communication. [ABSTRACT FROM AUTHOR]

In this study, we realize normal mode splitting in Fabry-Pérot (FP) microcavity structures containing cut wire (CW) metamaterials inside the cavity layer in the terahertz (THz) region. We used a wire grid (WG) structure to mirror the microcavity. To verify this concept, we analyzed the reflection and transmission properties of WG, CW, WG cavity (WGC), and microcavity containing CW (CWWGC) using transmission line theory. Consequently, we discovered that when the resonance frequencies of the CW and WGC matched, normal mode splitting occurred and anti-crossing is observed in the dispersion relation in the CWWGC. The samples are designed by the finite difference time domain method and were fabricated via photolithography. We measured the transmission spectrum of the fabricated samples by THz time domain spectroscopy. Finally, we observed a large splitting of the transmission peak owing to mode coupling between the light mode of the FP microcavity and the electric dipole mode of a single CW in the CWWGC. [ABSTRACT FROM AUTHOR]

We designed an ultrasonic horn using a physics-based freeform optimization method to achieve the target frequency response of an airborne ultrasonic MEMS transducer operating in transmitting mode. The radial profile of the ultrasonic horn was parametrized using a Bezier curve, and its shape was optimized using a genetic algorithm. A computationally fast compact model of the full system, wherein the horn was described analytically using transmission line theory, was used to calculate the frequency response of the transducer and evaluate the optimization objective. The result shows very good agreement with the experimental measurement of a realized prototype. [ABSTRACT FROM AUTHOR]

Glass windows are an important part of indoor‐to‐outdoor wireless communication channels, but the transmission loss of the normal glass limits the quality of the radio frequency (RF) signals, especially for the transverse‐electric (TE) polarized waves incident at large angles due to the impendence mismatch. Although some design methods for wide‐angle high RF transmission (WHRT) have been proposed recently, they can only work in a single frequency band. Here, an optically transparent metasurface is presented to realize high RF transmissions for dual polarizations in dual bands (2.2–3.2 and 4.4–5.2 GHz) and wide incidence angles (0–80°). The central frequencies of the two bands can be tuned independently by changing the structural parameters. A theory based on the transmission line (TL) model is proposed to explain the mechanism of the design, and a prototype is fabricated by using flexible printed circuit technology. The measured results of the prototype have good agreement with numerical calculations and full‐wave simulations. The design is expected to be beneficial to improve the quality of wireless signals in 5G systems. [ABSTRACT FROM AUTHOR]