Shorter frequency reuse distance in a densified small cell network for fifth generation (5G) could cause more substantial inter-cell interference. Rather than relying on down tilt, it is more necessary to design the azimuth patterns of the antennas to substantially reduce the gain at the sector edges which can reduce the line of sight radiation towards a sector positioned over a reuse distance. The antenna employs a modified ground plane, which utilizes both reflection and diffraction to reduce the gain at the sector edge, and is designed and prototyped from 3.5-4.2 GHz.

Fibre optic coupling is a critical component in optical communication systems, which involves efficiently transmitting optical signals from a light source to an optical fibre and efficiently receiving optical signals from the optical fibre to an optical detector. This process requires minimizing the loss of optical signals during the coupling process to maintain the performance and stability of the communication system. The complex environmental conditions and dynamic changes in optical systems that traditional optimization methods face often make it difficult to handle effectively. Therefore, this study uses deep reinforcement learning and adaptive optics technology to optimize fibre coupling efficiency. The optical fibre transmission performance is analyzed and optimized. Because the 2.6 Gb/s optical transmission system is a highspeed optical communication system capable of transmitting 260 million bits of data per second on a single optical fibre, this study selected the 2.6 Gb/s optical transmission system for single fibre three-way optical components. The optimization results show that the thickness of the isolator has been reduced by 2.356 mm, and the coupling efficiency has reached 79.95%. The optimized coupling steps can effectively optimize the coupling process, and the optimized optical components have high coupling efficiency, yield, and integration. The analysis of multiple sets of experimental data showed that the proposed method could improve the fibre coupling efficiency by an average of 15% to 20% under different environmental conditions. These data also show that the new framework performs well in optical path optimization and demonstrates excellent stability and real-time response capabilities in complex environments.

In this paper, the characteristic basis function method (CBFM) is accelerated to calculate the monostatic and bistatic normalized radar cross sections from one-dimensional highly-conducting sea surfaces in the microwave bands (C and Ku). In the framework of the two-scale asymptotic model, the subsurface length of the block is judiciously derived to contain all the surface curvature components (small scale) and the associated PBFs, assumed to be identical for all blocks, are rapidly calculated from the Kirchhoff approximation. In addition, the reduced matrix calculation is accelerated by neglecting the interactions between far blocks and by introducing a roughness slight approximation (matrix-matrix products can be done from fast Fourier transforms), which also allows us to expedite the resolution of the linear system since the matrix is sparse. Numerical results show the efficiency of CBFM-KA.

This paper demonstrates a Hybrid Fractal MIMO Antenna (HFMA) integrated with a Complementary Split Ring Resonator (CSRR) for fifth-generation wireless applications. Two radiating elements based on Meander and Minkowski Hybrid fractal geometry are included in the proposed design. The defected ground plane, along with CSRR, has been employed to enhance the isolation, bandwidth, gain, and other performance characteristics of the proposed HFMA. The proposed antenna was constructed using Rogers RT/duroid 5880 material. The designed model offers a maximum isolation of -55.86 dB and a wide bandwidth of 28.72 GHz, spanning the frequency range from 1.28 GHz to 30 GHz. All the diversity parameters of the designed antenna are found within operating limits. The proposed antenna is capable of covering multiple 5G spectrum bands, including LTE band 46 (5.15-5.925 GHz), 5G New Radio and 3.5 GHz frequency bands (3.3-5.0 GHz), the 26 GHz 5G spectrum, the European Union 5G spectrum (5.9-6.4 GHz), and is highly suitable for a range of other advanced applications, including Internet of Things (IoT), satellite communications, and vehicular networks in the frequency range of 1-30 GHz band.

We present a full-physics simulation workflow for modelling the installation and isolation of flush-mounted antenna arrays on rockets, which employs a combination of finite array domain decomposition method (FADDM) and shooting and bouncing rays (SBR) solver. An advanced domain decomposition method is first demonstrated, incorporating `non-identical' unit cells to efficiently solve a 4×4 antenna array residing in a metal cavity and operating in the X-band at 8.5 GHz. The proposed workflow eliminates the need for any computer-aided design (CAD) modifications for constructing conformal geometries of antennas and recesses in the fuselage, enabling seamless flush mounting of the array into an accurate model of a SpaceX Dragon capsule. The SBR simulation in the workflow is enabled with essential methodologies such as automati current conformance, creeping-wave physics, physical theory of diffraction, uniform theory of diffraction and current source reduction technique to obtain a high-fidelity yet computationally economical solution that determines radiation characteristics of installed antenna array and isolation between two flush-mounted antenna arrays.

By utilizing the symmetry of the field distribution of a coplanar waveguide (CPW) SSPP transmission line (TL), a half-mode SSPP (HMSSPP) transmission line (TL) is presented. Through electromagnetic simulations, it is demonstrated that the proposed HMSSPP TL has a lower asymptotic frequency than the CPW SSPP TL, while occupying only half of the size. Through equivalent circuit analysis, the miniaturization mechanism of the half-mode structure is revealed, and the method to further reduce the asymptotic frequency has been developed. The fabricated and measured HMSSPP TLs confirm the effectiveness and benefits of the half-mode transmission line, achieving significant size reduction and maintaining low insertion loss. Such compact transmission lines are particularly advantageous in space-constrained applications such as portable communication devices, radar systems, and compact RF modules for wireless sensing.

This paper introduces a compact dual-band wearable antenna designed for mmWave applications. The antenna is fabricated on a Rogers 3003 semi flexible substrate with dimensions of 15 × 15 × 1.52 mm³ and features a circular radiating patch with a full ground plane. Initially designed to resonate at 28 GHz, the antenna incorporates a square split-ring resonator in the ground plane to achieve an additional resonance at 38 GHz. To improve bandwidth and gain, a round necktie configuration is applied by adding two diagonal rectangular patches to the periphery of the radiating patch. The measured impedance bandwidths are 21.4% at 28 GHz and 23.7% at 38 GHz. The antenna achieves gains of 5.91 dBi and 4.57 dBi, with efficiencies of 90% and 78% at the respective operating bands. Simulated SAR values are 0.57 W/kg and 0.31 W/kg for 1 g and 10 g of human tissue at 28 GHz, and 0.18 W/kg and 0.16 W/kg at 38 GHz. These SAR values comply with FCC and ICNIRP safety standards. Additionally, bending tests illustrate that the antenna's performance was stable under deformation. As a result, the proposed antenna is ideal for fast connectivity 5G and biomedical applications since it efficiently spans fundamental mmWave frequency ranges.

In this paper, a tunable ultra-wideband antenna based on slot structures is presented and verified using Characteristic Mode Analysis. The antenna is backed with a partial ground plane and covers the 2.8-13.2 GHz frequency band. In this wide frequency range, satisfactory VSWR and gain are achieved. To avoid interference with wireless local area network WLAN (5.2 to 5.8 GHz) and X-Band satellite links (7.9 to 8.4 GHz), two notches are created using U-shaped and elliptical slots. An important feature of this paper is the use of varactor diode in the elliptical slot to achieve tunable frequencies for the second notched band. By applying different bias voltages, the center frequency of the second notched band is continuously tuned. The antenna performance is verified using modal parameters including modal significance and characteristic angle within the working region of the proposed antenna using the theory of characteristic modes analysis. This antenna is implemented on top of a cost-effective FR4 substrate with a 1 mm thickness. The proposed flower-shaped antenna is compact in size and provides ultra-wide bandwidth. The dimension of the optimized design is 25 × 35 × 1 mm³.

When permanent magnet synchronous motors (PMSMs) drive flexible loads, unknown disturbances (such as sudden load torque changes, parameter uncertainties, and unmodeled dynamics), can degrade the control performance of the system and may even cause irreversible physical damage. To deal with this problem, this paper presents an improved non-singular terminal sliding mode control (INTSMC) scheme based on a finite-time extended state observer. First, the acceleration feedback is introduced into the speed loop to establish the dual-inertia model of the PMSM flexible load system. Secondly, the conventional exponential reaching law is improved to obtain a novel reaching law with adaptive adjustment of the convergence speed, and a novel INTSMC controller is designed accordingly to enhance the system response speed. Then, a finite-time extended state observer (FTESO) is designed to estimate the disturbances of the system, and the estimated disturbances are compensated for the INTSMC controller to achieve convergence in finite time and improve the robustness of the system. The finite-time stability theory is used to prove the stability of the designed controller and observer. Finally, the simulations and experiments demonstrate the effectiveness of the proposed control scheme in improving the system’s anti-disturbance capability.

The proposed planar antenna features F and U shaped strips on the patch, along with U shaped slits on the ground plane, catering to WLAN/Bluetooth/WiMAX/HYPERLAN applications. Initially designed for a resonance frequency of 2.4GHz using standard formulae, the rectangular patch antenna boasts dimensions of 38.60 x 46.70 mm², totaling 1803 mm². However, employing the covering electrical length technique, the proposed antenna effectively reduces size for multiband applications. The lengths of the strips determine the resonance frequencies, while the U shaped slits facilitate adjustment of resonance frequencies as required. Following parametric optimization, the rectangular patch antenna becomes suitable for multiband operation, shrinking in size by up to 71.47% compared to its original form. The proposed antenna achieves resonance at 2.45 GHz, 3.55 GHz, and 5.37 GHz, effectively covering WLAN, Bluetooth, Zigbee, WiMAX, and HYPERLAN frequencies. Despite size reduction, the antenna maintains acceptable gain, ensuring its viability for multiband operations. The compact dimensions of the proposed planar antenna measure 39.5 x 13 mm², making it ideal for integration into small portable devices such as mobile handsets, laptop computers, and USB dongles. Following fabrication, various parameters of the antenna are measured using a Vector Network Analyzer (VNA), including reflection coefficient, Voltage Standing Wave Ratio (VSWR), and impedance.

A planar, short-circuited dipole design, constructed from cutting a flat metallic plate, capable of operating in the 2.4/5/6 GHz Wi-Fi 8 bands and also the 6G upper mid-band in the 7125-8400 MHz range is presented. The antenna comprises two folded dipole arms, each of which has a cut-out portion, with one short-circuiting portion connecting them. The plate dipole can operate at its 0.5-, 1.5-, and 2.5-λ resonant modes with two higher-order resonances forming a very wide 10-dB impedance bandwidth of about 5.0-9.4 GHz, easily covering the 5150-8400 MHz band for the 5/6 GHz Wi-Fi bands and the 6G upper mid-band. The design is simple in structure, has a compact size of 10 mm × 30 mm (0.08-λ × 0.24-λ at 2.4 GHz), and also shows good radiation performance. The design concept is elucidated and discussed in this paper with the numerical and experimental results.

This paper proposes a spin decoupling phase gradient (SDPG)-scalar holographic impedance (SHI) bidirectional hybrid metasurface (MTS). The integrated SDPG MTS modulates the space wave (SPW) and is excited by the horn, whereas the SHI-integrated MTS modulates the surface wave (SFW) and is excited by a surface-mounted monopole. As example, (1) Dual orbital angular momentum (OAM) beams are generated at 18.3 GHz by the integrated SDPG MTS at 18.3 GHz: left hand circular polarization (LHCP) (OAM mode l₁ = 1, θ₁ = 30˚, φ₁ = 0˚), right hand circular polarization (RHCP) (l₂ = -1, θ₂ = -30˚, φ₂ = 0˚). (2) Linear polarization (LP) pencil beam is generated at 7.8 GHz by the integrated SHI MTS: (l₃ = 0, θ₃ = 150˚, φ₃ = 0˚). The peak gain is 19.9 dBi, and the OAM purity is above 84.7%. The novelty of the manuscript is as follows: (1) To the authors' knowledge, a full-space SDPG-SHI hybrid metasurface has been developed for the first time, which greatly expands the bidirectional multifunctional design freedom. (2) Much higher aperture efficiency (AE) than published results. (3) The proposed SDPG-SHI hybrid MTS simultaneously possesses the following advantages: small size (π × 7.19λ × 7.19λ at 18.3 GHz, and π × 3.06λ × 3.06λ at 7.8 GHz), full space, multibeams, multipolarization, reconfigurability and simultaneous modulation of SPW and SFW. The developed MTS has promising applications in high-capacity bidirectional communication scenarios.

The paper summarizes the principles of various reflectors for microstrip antennas with a particular focus on volumetric reflectors (cavities) that are more challenging to manufacture than flat structures made from printed circuit boards or sheet metal. It is demonstrated in this study that volumetric reflectors can significantly enhance the directional properties of an antenna without typically increasing the antenna's radiating area or overall volume. To reduce the manufacturing costs associated with antenna's volumetric parts, the article proposes the use of 3D printing with commonly available dielectric materials, such as plastics. This technique is relatively straightforward and cost-effective compared to the manufacture of volumetric metal parts. Moreover, the article suggests applying a conductive layer to the parts of the antenna that contribute to radiation formation. The option of covering the reflector (cavity) on the inside with ordinary aluminum foil and the option with conductive enamel are considered. The results of simulation in antenna designs with different reflector conductivities and the results of experimental studies of antennas are presented. The results obtained show that the method is feasible to be used with virtually no compromise on the antenna characteristics and substantially reduces the production cost.

Direction of arrival (DOA) estimation is an important issue for radar and communication applications. Monopulse is widely used to obtain the DOA result by the complex ratio from the sigma and delta beams of the antenna. In the case of digital array systems, various methods based on the covariance matrix of the received signal have been proposed to obtain the DOA result. However, it is impractical for tracking radar scenarios, as the covariance matrix is not easy to obtain. Nevertheless, there is merely one target echo in the vicinity of the range cell as forecasted. Thus, the Maximum Likelihood Estimation (MLE) is a relatively good estimator for tracking radar, which has high accuracy and robustness. However, MLE is often very computationally resource-intensive, as it needs to search the whole steering vector set. In this paper, in order to utilize MLE effectively, we propose an algorithm to quickly search the steering vector set by the binary tree hierarchical matching method, which can significantly reduce the computational cost. Furthermore, the computational complexity and accuracy performance have been studied from both theoretical analysis and simulation perspectives.

To address the issue of large inductor current ripple in the existing finite switching sequence model predictive control (FSS-MPC) strategy for quasi-Z-source inverters (qZSI), an improved switching sequence model predictive control strategy is proposed. First, the switching sequences and inductor current ripple characteristics of the existing strategy are analyzed. Then, the voltage vectors are rearranged, and eight switching sequences with shoot-through vectors are designed within one sector. Next, the duty cycles of the voltage vectors are calculated based on the inverse relationship between the duty cycle and the cost function value. Additionally, a weighting coefficient for switching times is introduced into the cost function. Finally, simulations and experiments are conducted to compare the proposed method with the conventional FSS-MPC strategy. The results verify the feasibility and effectiveness of the proposed control strategy.

This paper presents a study of a novel optically transparent planar antenna operating at a resonant frequency of 8.5 GHz, specifically designed for WiMAX wireless communication systems. The antenna is fed by a 50 Ω microstrip line and exhibits a wide operational bandwidth. Measuring 30 × 30 mm² and achieving an optical transparency exceeding 70% of glass, the proposed antenna delivers outstanding performance while minimizing its visual impact. It is fabricated using an innovative rectangular meshed pure copper grid layer, deposited on a 0.7-mm-thick borosilicate flat glass substrate, optimizing both transparency and conductivity. Experimental evaluations of key performance parameters, including the reflection coefficient, radiation pattern, and gain, were conducted to assess the antenna's effectiveness at the target frequency of 8.5 GHz. The measured results confirm that the antenna exhibits excellent impedance matching at 8.5 GHz, achieving a peak realized gain of 5.2 dBi. These findings demonstrate the feasibility of transparent antennas that offer performance on par with non-transparent alternatives, while providing distinct aesthetic advantages. As a result, the proposed antenna presents a viable solution for applications requiring both functionality and visual integration, such as smart devices and architectural installations.

In this letter, a compact passband filter with dual desirable attenuation narrow bands is developed for ultra wideband application. Indeed, a grounded stepped impedance resonator in defected microstrip structure (GSIR-DMS) is realized with a specified high pass cutoff frequency of (f GSIR ). Next, two cells of the designed GSIR-DMSs are cascaded to perform the proposed ultra wide passband filter. In addition, four λ_g/4 open-circuited stubs are inserted beside the GSIR-DMSs to create two transmission zeros and improve the filter rejection performance. In order to suppress interference with some expected network channels, two desirable λ_g/4 short-circuited microstrip stubs are implemented and coupled to the body of the UWB filter. Finally, the filter is constructed, simulated, and measured using a Rogers-ceramic RO4360 substrate with a permittivity of ε_r = 6.15 and a thickness of h = 1.016 mm. The filter responses from measurement and simulation are compared and discussed. The produced filter is very small covering circuit area of about (0.433λ_g × 0.244λ_g) excluding the feeding ports.

A circular-slot embedded elliptical patch antenna with DGS ground is introduced for Wi-Fi, Bluetooth, Sub 6 GHz 5G, IRNSS, Wi-Max, and WLAN wireless network applications. The design consists of an elliptical radiating patch featuring a circular cutout positioned on the uppermost layer of the substrate, while the under layer incorporates a DGS structure with two symmetrical slots. The antenna is implemented on an FR4 substrate having a thickness of 1.6 mm and is excited using a microstrip line feed. The structural layout of the antenna corresponds to dimensions of 0.87λ × 0.81λ × 0.02λ. The developed antenna achieved a bandwidth of 86.74%, encompassing a BW extending from 1.73 to 4.38 GHz maintaining a reflection coefficient (S₁₁) lower than -10 dB, exhibiting 5.1 dB of peak gain. The radiation characteristics and surface current density distribution are examined at specific frequencies of 2.4 GHz, 2.78 GHz, 3.5 GHz, and 3.95 GHz. Additionally, the antenna's evolution and parameter effects were examined to better understand its performance characteristics.

To reduce the prediction times and algorithm complexity of model predictive current control (MPCC) for permanent magnet synchronous motor (PMSM), a simplified duty cycle modulation model predictive current control without cost function (SDCM-MPCC) method is proposed. The proposed method uses two fixed voltage vectors to generate the three-phase duty cycles for any sector, which is directly applied to the inverter after correction, without using a cost function to traverse the combination and modulation of voltage vectors in different sectors with only 1 prediction. Deadbeat control on the d-q axis current is performed simultaneously to obtain the duty cycle for two fixed voltage vectors. The output voltage vectors can cover any amplitude and direction, effectively reducing current ripple and phase current harmonics. Simulations and experiments confirm the method's effectiveness and feasibility.

In this study, we evaluated the feasibility of intra- and peritumoral artificial intelligence (AI)-based radiomics from Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for preoperative prediction of lymphatic vascular invasion (LVI) in invasive breast cancer (IBC). Our results demonstrated that a radiomic model (area under the receiver operating characteristic curve AUC = 0.951) outperformed a clinical model (AUC = 0.644) in 193 patients. Optimal tumor segmentation using 3D RU-Net (Dice score > 0.75) and 3 mm to 4 mm isotropic 3D peritumoral expansion yielded the strongest predictive performance.