Arbitrarily shaped near field with arbitrary polarization is practical application requirements. Our previous work proposed combining the phase conjugation (PC) and planar tensor impedance modulated holographic metasurface (TIMHMS) for arbitrarily shaped near field with arbitrary polarization. This paper proposes to generate arbitrarily shaped near field with arbitrary polarization by cylindrical conformal TIMHMS based on PC and Blackman window function. For the first time to the knowledge of the authors, arbitrarily shaped near field with arbitrary polarization is generated by conformal TIMHMSs. As example, two cylindrical conformal TIMHMSs are constructed at 30GHz for rectangle-shaped near field: (LHCP, z = 100 mm) and (LP, z = 200 mm), where LHCP and LP are left hand circular and linear polarizations, respectively. Blackman window function is used to optimize the cylindrical conformal TIMHMS design for optimized field pattern efficiency and low sidelobe. The calculated, simulated, and measured results agree well, and validate the proposed design method for conformal TIMHMS. The designed conformal TIMHMSs have the advantages of high pattern efficiency 42.1%, flexibly shaped field patterns and polarizations, and low sidelobe (-15 dB). The design method does not need complicated calculations and can be used in the upcoming sixth-generation wireless networks with required shaped nearfield for Radio Frequency Identification, holographic imaging, biomedical applications, etc.

Single-photon sources with high repetition rates have been a focal point of modern research for decades. However, their application in underwater environments is significantly limited due to the absorption properties of water, which hinder the propagation of most optical wavelengths. This study addresses the challenge by reporting on-demand single-photon extraction suitable for underwater quantum communication. The use of plasmonic nanoantennas can significantly enhance the spontaneous emission of single-photon sources. Nonetheless, a primary challenge is the nanoscale guiding of emitted photons in underwater environments. To overcome this, a more sophisticated design is required to enhance photon emission and achieve momentum matching with water. Here, we present a topology-optimized design of underwater plasmonic nanoantennas to mitigate these limitations. The nanoantenna consists of an optimized gold pattern and a silicon nitride substrate. Consequently, the normalized extraction decay rate (γ_e⁄γ₀) can reach 4.02 at a wavelength of 517 nm, which is within the blue-green spectral range, when using an objective lens with a numerical aperture of 0.6 (cross-section angle of 26.7°). The proposed design approach for plasmonic nanoantennas is versatile and holds promising potential for various applications, particularly in advancing single-photon technologies for quantum communication.

Brain tumors are characterized by the fast growth of aberrant brain cells, which poses a considerable risk to an adult's health since it can result in severe organ malfunction or even death. Magnetic resonance imaging (MRI) provides vital information for comprehending the nature of brain tumors, directing treatment approaches, and enhancing diagnostic precision. It displays the diversity and heterogeneity of brain tumors in terms of size, texture, and location. However, manually identifying brain tumors is a difficult and time-consuming process that could result in errors. It is proposed that an enhanced You Only Look Once version 8 (YOLOv8) model aids in mitigating the drawbacks associated with manual tumor detection, with the objective of enhancing the accuracy of brain tumor detection. The model employs the C2f_DySnakeConv module to improve the perception and discrimination of tumors. Additionally, it integrates Content-Aware ReAssembly of FEatures (CARAFE) to efficiently expand the network's receptive area to integrate more global contextual information, and Efficient Multi-Scale Attention (EMA) to improve the network's sensitivity and resolution for lesion features. According to the experimental results, the improved model performs better for brain tumor detection than both the open-source model and the original YOLOv8 model. It also achieves higher detection accuracy on the brain tumor image dataset than the original YOLOv8 model in terms of precision, recall, mAP@0.5, and mAP@0.5~0.95 above, respectively, of 2.71%, 2.34%, 2.24%, and 3.73%.

Wireless connections in 5G technology are driving the rapid growth of intelligent transport systems and vehicle communications. Wireless channels are impacted by weather, which is most noticeable in millimeter wave bands. This includes rain, fog, snow, sand, and dust. 5G networks now support diverse applications with speed and quality. In an effort to enable the use of millimeter wave frequencies, a recent study examined the impact of dust and sand on 5G channels. This paper examines the impact of heavy and frequent rainfall, along with horizontal polarization, on the propagation of millimeter waves in urban and highway settings. Using theoretical and optimization techniques, the effects of rainfall attenuation, path loss, and connection margin are evaluated at various millimeter wave frequencies. Dependencies on rainfall rate, path variation, and operating frequency are shown by the simulation results. In urban and highway situations, mean path loss and error statistics are examined with and without rainy attenuation. It is observed that the particle swarm optimization approach achieves 94% accuracy in signal propagation, which will enhance the path loss, received power and overall system performance.

A compact UWB-MIMO antenna designed for sub-6 GHz, Ku-band, and millimeter-wave applications with UWB capabilities is proposed. The antenna design consists of two inverted L-shaped MIMO elements with slot etching, deliberately positioned on an FR-4 material substrate, measuring 36 × 18 × 1.6 mm³. Utilizing inverted L-shaped elements and prudently arranged slots on the substrate, the design achieves wideband characteristics. For enhanced isolation, interconnected rectangular slots with a fork shape are etched in the bottom layer, ensuring isolation of less than -25 dB between ports. The proposed design exhibits an impedance bandwidth of approximately 54% within the frequency range of 3 GHz to 40 GHz, making it suitable for sub-6 GHz 5G bands, Ku-band, and millimeter-wave applications. The advantages of compactness and low profile of the proposed design are best suitable for 5G, Ku-band, and millimeter applications with UWB capabilities. The proposed design is successfully fabricated and tested.

This article introduces a compact design for a four-element MIMO antenna for millimeter-wave (mmWave) communications for specifically n261 band having range from 27.5 GHz to 28.35 GHz with a bandwidth of 850 MHz. The single antenna structure uses a rectangular patch having four diamond-shaped slots in the feed-plane. On the ground plane, a dumbbell-shaped slot is positioned below the rectangular patch. A Rogers RT/Duroid 5880 substrate with ultra-thin thickness is used in this design. The optimized design for four-port MIMO antenna has small size with dimensions of 20 mm × 19 mm × 0.254 mm. The MIMO parameters such ECC is less than 0.011, and DG is greater than 9.90 dB in the mentioned band, which are within tolerance limits. The isolation between neighbouring MIMO elements is also less than -19.5 dB.

This work investigates low-power electromagnetic energy harvesting at 2.4 GHz and 5 GHz using an elementary rectangular patch rectenna along with a step-up DC-DC boost converter. The receiving antenna is optimized to 50 Ω impedance by tuning parasitic ground plane stubs in the resonating frequencies. The return loss and gain of the proposed antenna are -30.19 dB, -31.02 dB and 2.45 dBi, 4.84 dBi at 2.4 GHz and 5 GHz respectively. A single-stage Greinacher voltage multiplier with a compact dual-band pi-model matching circuit is proposed as a rectifier. The rectenna is manufactured on an FR4 substrate, and the measured performance is in good agreement with the simulated results. The transformation efficiency of more than 40% is noticed in the wide input-power range from -12 dBm to 5 dBm. The maximum efficiency of 50% and DC output voltage of 1.57 V at 0 dBm input power with 5.1 KΩ optimized load resistance is noticed when the RF source and rectenna are 46 cm apart. The proposed rectenna with a DC-DC boost converter can drive the LED indicator and wall clock simultaneously. The prototype rectenna is suitable for energizing low-power sensor nodes in IOT and WSN applications.

Quantum emitters coupled to plasmonic nanostructures can act as extremely bright single-photon sources. Interestingly, the mode volumes supported by the plasmonic nanostructures can be several orders of magnitude smaller than the cubic wavelength, which leads to dramatically enhanced light-matter interactions and drastically increased photon emission. However, the requirements of a small mode volume for emission speed-up are always contradictory with a sufficiently large mode volume for efficient extraction, especially in a single architecture. Here, we report the design of a topology-optimized plasmonic nanoantenna to alleviate the above limitation which could greatly enhance far-field photon extraction. The plasmonic nanoantenna is composed of an optimized gold pattern and a silicon nitride substrate, with a nanohole in the center of the gold pattern. Our design is based on density-based topology optimization and is inherently robust to dimensions and fabrication errors. As a result, the normalized extraction decay rate (γ_e⁄γ₀) can reach 5.48 at a wavelength of 517 nm if an objective lens with a numerical aperture of 0.45 is utilized. Plasmonic nanostructures can be obtained with a small mode volume of about 5 × 10^-21 m³, while emission speed-up could still be achieved. The proposed method to alleviate the contradiction of plasmonic mode volume could brighten the prospects for future integration of single-photon sources into photonic quantum networks and applications in quantum information science.

To reduce large torque ripple in permanent magnet-assisted switched reluctance motors (PMa-SRMs), a novel direct instantaneous torque control (DITC) strategy with zero-voltage modulation is proposed in this paper, where a fixed-frequency pulse width modulation (PWM) is replaced by the conventional DITC hysteresis controller to optimize zero-voltage insertion time through zero-voltage decentralized modulation to minimize switching losses. Control intervals are then divided based on inductance and torque-to-current ratio (TCR) characteristics, with adaptive duty cycle adjustments to enhance torque tracking and reduce ripple. Additionally, the optimal turn-on and turn-off angles are determined by the dung-beetle-optimized back propagation (BP) neural network (DBO-BP) algorithm, which suppresses the torque ripple, lowers phase current peaks, and improves motor efficiency. The feasibility and effectiveness of the proposed method are validated by simulations and experiments with a three-phase 6/20 PMa-SRM.

Conventionally, the thinning process in antenna arrays was performed at the element level with random selection after examining all the possible combinations. Thus, the computational time of such thinned methods was relatively high. Reducing the undesirable high computational time is of great interest. In this paper, the thinning process is performed at subarray level rather than element level, thus, the computational time and array complexity were significantly reduced while minimizing the peak side lobe level (PSLL). The optimization process consists of two steps where in the first step the array elements are portioned into a number of nonuniform ascending subarrays, while in the second step some of the least significant subarrays were turned off. Moreover, two schemes were used to portion the array elements. The first one is based on portioning all the array elements into ascending subarrays. This is known as fully nonuniform ascending subarray configuration since the entire array elements were portioned into smaller unequal groups. The second one is based on portioning only part of the elements located at the sides of the array, while leaving the central elements individually without any partition. This is known as partially nonuniform ascending subarray configuration. The genetic optimization algorithm is used to find out optimally which subarrays need to be thinned (or turned off) by setting their excitation amplitudes to zero. The simulation results for a total of 100 elements linear array illustrate that the PSLL, in the full subarray configuration, can be minimized to more than -33 dB by thinning 5 subarrays and the complexity reduction percentage was 72% before thinning and it becomes 82% after thinning. On the other hand, the PSLL in the partial subarray configuration was reduced down to more than -30 dB by thinning 4 subarrays at each side of the array. In this case. The complexity reduction percentage was 52% before thinning, and it becomes 60% after thinning. The number of individual central-elements on both sides of the array was 26, and the number of subarrays on both sides of the array was 22. Furthermore, the idea of the thinned subarrays was successfully extended and applied to the two-dimensional planar arrays of 100 × 100 elements.

This work explores the potential of spoof surface plasmon polaritons (SSPPs) for effectively feeding high-frequency antennas operating in the extremely high-frequency (EHF) range. An innovative approach is introduced in this study to utilize SSPP to feed a dielectric rod antenna. The design incorporates a straightforward dielectric rod antenna fabricated using FR-4 material with a relative permittivity of 4.3. Compared to conventional tapered dielectric rod antennas and their corresponding feeding configurations, this design presents the potential benefit of achieving an improved gain of up to 16.85 dBi using a specific antenna length of 7.6λ₀. Through careful design optimization, we achieved impedance matching and directional radiation characteristics at a frequency of 7.3 GHz. To validate our design and assess its performance, we conducted simulations using the CST Microwave Studio. This study aims to demonstrate the effectiveness and practicality of the proposed dielectric rod antenna with an SSPP feed.

This paper proposes a variable flux leakage permanent magnet (PM) machine and investigates the impact of slot and pole number combinations on the electromagnetic performance of a variable flux leakage permanent magnet machine (VFL-PMM). The stator armature winding dq-axis magnetic circuit is designed to couple with the PM leakage magnetic circuit by the deliberate establishment of a leakage-guided magnetic barrier and a poly-magnetic barrier on the rotor side. The VFL-PMM with 12s10p-DL (double layers) fractional slot centralized winding (FSCW) serves as an illustrative example of global parametric modelling of the machine. The objective is to optimize the split ratio, average torque, torque ripple, and PM utilization of the machine to obtain the optimum amount of the machine. The relationship between the no-load, on-load characteristics, and variable flux leakage characteristics of 12s8p, 12s10p, 12s14p with double-layer FSCW and 12s10p with single-layer FSCW are studied comparatively. The machines are analyzed and optimized using 2D finite element analysis.

In this paper, a novel stacked wideband differentially feed antenna with dual polarizations is designed for base station. The circular parasitic patch deepens the resonance depth by slotting. Two linear dipoles are placed at ±45° under the circular parasitic patch to reduce the overall size of the antenna. The antenna introduces a cross-shaped differential feed to achieve high port isolation. Finally, the designed antenna is fabricated and tested. The test results show that the differential reflection coefficient |Sdd11| is more than 15 dB. The antenna achieves a differential impedance bandwidth of 53.1% (1.63 GHz-2.8 GHz). The isolation is greater than 42 dB over the entire operating bandwidth. The antenna also has a stable gain of 8.2±0.4 dBi and a half-power beamwidth of 65°±4°.

To address the issues of high current harmonic and power ripple in the traditional Finite Control Set Model Predictive Control (FCS-MPC) strategy for virtual synchronous generator system with quasi-Z-source inverter (qZSI-VSG), a double and triple-vector hybrid modulation model predictive control strategy is proposed. This strategy utilizes the inductor current sub-cost function to select the shoot-through state (ST state) or the non-shoot-through state (NST state). When NST state is selected, the voltage vector combinations in the double-vector and the triple-vector are initially established. Then, the voltage vector combinations are reduced from 18 groups to 6 groups by using the vector combination quick selection table. Subsequently, the duty cycle of each voltage vector is then determined based on the value of its cost function, and the voltage vector is re-synthesized. Finally, the predicted values of all control variables are calculated and substituted into the cost function for optimization. Experimental results show that the proposed strategy reduces 48.62% of current harmonic, 50% of active power ripple and 25.53% of capacitor voltage ripple compared to the traditional strategy, which effectively improves the system control performance.

In order to effectively reduce the loss of the filter, decrease its size, and improve its frequency selectivity, a miniature filter unit has been proposed. This unit offers enhanced frequency selectivity and facilitates adjustment of the center frequency. The filter unit is constructed by embedding a serpentine microstrip resonator in the upper metallic surface of a half-mode substrate-integrated waveguide (HMSIW). The center frequency of the filter unit is considerably lower than the cutoff frequency of the HMSIW, which contributes to the miniaturization of the filter. The center frequency of the filter unit can be adjusted solely by modifying the dimensions of the microstrip resonator, while the dimensions of the remaining components can be maintained at a constant value. A transmission zero has been incorporated into the upper resistance band with the objective of enhancing its frequency selectivity. A second-order filter with a center frequency of 3 GHz is accurately designed using this filter unit. The results demonstrate that a miniaturized filter with the desired center frequency and excellent performance can be rapidly achieved using this filter unit, which has potential applications in the 5G (sub-6G) band.

Optical materials whose permittivity becomes negative for certain wavelength ranges, so-called plasmonic materials, have been widely used for biochemical sensing applications to detect a wide variety of analytes from chemical agents to protein biomarkers. Since many analytes are or contain nanoscale objects, they interact very weakly with light. Thus, light confinement is a key to improving sensitivity. Using metal or plasmonic nanostructures is a natural solution to confine light and boost light-matter interactions. As there are several different optical sensing schemes, such as refractometric sensing, fluorescence-labeled sensing, and vibrational spectroscopy, whose operating wavelength spans from ultraviolet to mid-infrared wavelength regions, some plasmonic materials are superior to others for certain wavelength regions. In this article, we review current progress on alternative plasmonic materials, other than gold, silver, and aluminum, used in biochemical sensing applications. We cover a wide variety of plasmonic material platforms, such as transparent conductive oxides, nitrides, doped semiconductors, polar materials, two-dimensional, van der Waals materials, transition metal dichalcogenides, and plasmonic materials for ultraviolet wavelengths.

In order to meet the current demand for 5G smartphone antennas, this paper introduces a six-port dual-band multiple-input multiple-output (MIMO) antenna designed for 5G smartphones. Based on multimode, the antenna achieves multiple band coverage in a limited space, making it of significant practical value in 5G cell phone antenna applications. The antenna features a structure comprising a modified L-shaped patch antenna, a gun-shaped slot in the ground plane, and two small stubs extending from the metal ground. This configuration creates a multimode antenna that is excited by two coupled feed loop modes and two slot modes. The feeder strips, which have been enhanced with L-shaped slots, form tuned branches, enabling the co-excitation of multiple modes. The MIMO system can operate within the frequency range of 3.3-3.8 GHz and 4.4-7.5 GHz (S₁₁ < -6 dB), covering the 5G communication bands including n78 (3.3-3.8 GHz)/n79 (4.4-5.0 GHz) and the LTE Band 46 (5.15-5.925 GHz). Additionally, the antenna exhibits an envelope correlation coefficient of less than 0.18, antenna efficiency ranging from 60% to 93%, and isolation between adjacent antenna elements better than 12.9 dB.

Sparse arrays have the technical advantages of large equivalent aperture, high degrees of freedom (DOFs), and low mutual coupling leakage. In this article, a novel symmetric sparse array, termed as symmetric shifted coprime array (SSCA), is proposed for the localization of both the far field and near-field of sources. It can be generated in two steps. Firstly, the second subarray of the traditional coprime array is shifted by a appropriate distance, and secondly, the entire array is flipped. By translating, the proposed array provides increased DOFs and enhanced ability to resist heavy levels of mutual coupling. Meanwhile, the symmetric structure of the array can be ensured by flipping to solve the parameter estimation of mixed fields. We provide an analytical expression for the proposed array and also derive its DOFs and weight functions. The first three weight functions of SSCA are equal to 2, indicating that the SSCA improves the ability to resist mutual coupling. Numerical results show that the proposed array is superior to existing sparse arrays for both direction of arrival (DOA) and range estimations.

Conventional hairpin band-pass filters (BPFs) typically have poor stopband performances. Therefore, this paper proposes a BPF with a center frequency of 24 GHz that employs a novel hairpin-coupled structure. An enhanced hairpin-coupled resonator topology is also introduced to improve the stopband suppression characteristics. Specifically, the proposed resonator and filter are configured through a hairpin structure and source-third resonator coupling, which afford a miniaturized size and coupling of the transmission zeros. Then, an equivalent circuit model is simulated to conduct loss analysis of the millimeter-wave (mm-wave) BPF, and the corresponding analytical parameters and result data are extracted. Furthermore, fast synthesis is achieved for the high stopband suppression mm-wave filter. The compact BPF developed is fabricated using the quart glass process, with the corresponding measurements revealing that the insertion Loss (IL) is less than 4.5 dB, and the return loss (RL) exceeds 9 dB within the passband. Meanwhile, the stopband suppression at 20.6 GHz and 28.6 GHz can reach 43 dB and 35 dB, respectively. Those advanced performances demonstrate the promising prospect of the proposed filter for its application in biological radar life feature monitoring.

A compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with four stopbands is designed and experimentally investigated. By the method of coating, various T-shaped structures and split-ring resonators (SRRs) are used for suppressing the mutual coupling and introducing the band-notched characteristics, respectively. The actual design has an overall size of 46 × 37 × 1.57 mm³ across the whole UWB spectrum from 2 to 22 GHz except stopbands from 3.47 to 3.83 GHz, 5.2 to 5.85 GHz, 7.19 to 7.84 GHz, and 8.15 to 8.6 GHz, which prevent the interference of Microwave Access (WiMax), wireless local area network (WLAN), satellite downlink and satellite communications band (ITU 8 GHz) bands, respectively. Besides, the isolation of the most operating frequencies is higher than 20 dB, and the antenna obtains a fairly stable radiation pattern and gain, as well as a lower envelope correlation coefficient (ECC < 0.005). Additionally, using the antenna inserted in name badge of the doctor, the chance of infection will be greatly reduced. Ultimately, the proposed MIMO monopole antenna has a potential application in the medical domain.