To address the issues of complex current demodulation, large rotor position estimation error, and position estimation error varying with speed in the high-frequency (HF) rotating voltage injection (HRVI) method for interior permanent magnet synchronous motor (IPMSM), a sensorless control of IPMSM with triangular transform (TT) current self-demodulation in the estimating d-q axis is proposed. Firstly, the HF currents estimated on the d and q axes are multiplied, and the resulting signal is constructed through TT to achieve phase shift compensation of positive and negative sequence HF currents. At the same time, a position error signal is constructed. Then, a low-pass filter is used to extract the position error signal and achieve self-demodulation of the current. The experimental results show that this method reduces the average position error by 15.0% under steady-state conditions and reduces the fluctuation range of position error by 17.6% under full load conditions.

This paper utilizes an efficient prediction model using the concept of ray-tracing based on the Theory of Geometrical Optics (GO) to predict the signal strength between two wireless sensor nodes within an indoor environment, which can provide aid to designers in the implementation of Wireless Sensor Networks (WSNs). WSN is a technology that is widely used for functions such as collecting and processing data, then transmit it wirelessly within the network. WSNs are typically autonomous and self-organizing networks of nodes that communicate wirelessly with each other and collaborate to perform tasks such as data processing, sensing, aggregation, and forwarding. With the increasing prevalence of WSNs in indoor environments, installations of numerous sensor nodes are necessary to collect and transmit data in certain areas, which builds up to a single network. Thus, to ensure the functionality of the WSNs, it is of utmost importance to ensure a reliable connection between the nodes, which is directly affected by its location and placement. The prediction model developed in this work is built using MATLAB software, which is then implemented into a Graphical User Interface (GUI) using MATLAB App Designer, which allows modifications to be made to the prediction model as to fit the user’s environment. The results of our prediction model are compared against experimental ones obtained through physical measurements using wireless communications technologies such as ZigBee and Bluetooth Low Energy (BLE).

An all-optical compact polarization T splitter based on 2-dimensional photonic crystal with uniform structural and bandgap characteristics is proposed in this paper. A square lattice of silicon substrate with embedded air holes is used to create the proposed structure. Linear waveguides with 90˚ bends are created for light propagation by removing a number of holes to build the structure. Plane Wave Expansion and Finite Difference Time Domain methods are employed for simulating the structure. The transmittance of TE polarized mode at 1550 nm is 96%. The structural parameters, such as air hole radius and dielectric constant, are homogeneous throughout the structure, making production easier and reducing fabrication errors. The proposed polarization splitter has a simple design with small footprints and high Q factor to meet the demands of current optical integrated circuits.

An accurate, efficient and scalable SPICE model is essential for modern integrated circuits design, especially for radio frequency (RF) circuit design. A PSP based scalable RF model is extracted and verified in 0.11 μm CMOS manufacturing process. The S parameter measurement system and open-short de-embedding technique is applied. The macro-model equivalent subcircuit and parameters extraction strategy are discussed. The extracted model can match the de-embedded S parameters data well. By combining the model parameters' dependencies on each geometry quantity, the scalable expression of parameters with all geometry quantities included can be obtained. This work can be a reference for the RF MOSFETs modeling and RF circuit design.

In this paper, a rectangular patch antenna that covers the band from 3.2 to 5.7 GHz to support 5G New Radio (NR) sub-6 GHz with high gain and efficiency is designed and implemented. Particle Swarm Optimization (PSO) algorithm is used to get the dimensions of the antenna and slots. The optimization goals are to reach the smallest dimensions of the antenna in the required bandwidth keeping scattering parameter at port 1 |S₁₁| below -10 dB, a gain of 4 dBi or higher, and efficiency more than 90%, respectively. The resonance frequency of a microstrip patch is 4.45 GHz. PSO using the computer simulation tool (CST) software is used to design an antenna with desired frequency response and radiation characteristics for 5G New Radio (NR) sub-6 GHz. The antenna is designed over an FR-4 substrate with a noticeable reduction in cost, simplicity in design, and a small overall size of 23×15 mm². The antenna is with the partial ground. The antenna has two parallel stubs and EL slots; the lengths of these slots control the desired bandwidth. A high agreement between the simulated and measured results is noticed.

This letter investigates a differential, planar and wideband antenna on a commercial organic printed circuit board (PCB) substrate at 240 GHz with a novel packaging concept to integrate massive monolithical integrated circuits (MMICs). The antenna utilizes multiple series resonators to achieve a bandwidth of 75 GHz around 240 GHz. A novel differential bond wire package solution from chip to antenna feeds the differential antenna from an on-chip Marchand balun. The fabrication of the antenna and interconnect are analyzed, and potential improvements for future works are highlighted. Measurement proves the function of the designed package, which is competitive to the state of the art.

To improve the work efficiency of on-site inspection personnel in diagnosing faults of power transmission lines, in this paper we propose an infrared image segmentation method based on DeepLabV3+ for identifying key components of transmission line. We collected 556 infrared images of transmission lines in our own power supply system, and expanded the original data by data augmentation method. Based on the comparison of the DeepLabV3+ model with three different backbone networks, MobileNetV2 with the best performance is selected as the main backbone network. Compared with FCN, U-Net and SegNet, the test results show that DeepLabV3+ using MobileNetV2 (compared with ResNet50 and Xception) can segment the five types of key components in power transmission lines from infrared images more accurately and faster. The MIoU on the test set is 0.8624, which is better than the performance of FCN, U-Net and SegNet. This lays a foundation for improving the work efficiency of on-site inspection personnel and improving the continuous power supply capacity, stability and safe operation level of the power grid.

The far-field gain of commercial horn antennas primarily depends on aperture area and flare length. Traditionally, for every dBi of gain increment, the flare length should increase by 20% and the aperture area by 10%. External lens classes, such as gradient refractive index, concave, or Fresnel, are used to improve gain by ≤ 2 dBi, but at the cost of a volumetric increase by 75% in the range of 4.8-6 GHz. We propose a hollow dielectric loading (HDL) loaded in the flare section of the horn antenna. The shape and position of the HDL are optimized using an evolutionary algorithm to obtain the maximum gain from a conical corrugated horn antenna (CCHA) at boresight. The optimized design yielded a total volume 84% smaller than traditional external lenses while achieving 3.5 dBi peak gain improvement in the operating frequency range. We also observed an improvement in the electric field by 24% while retaining parity in the impedance bandwidth. A 3D-printed prototype of the optimized CCHA and the HDL is fabricated and measured. The measured and simulated results demonstrated good agreement with a maximum difference of 4%.

The next-generation communication network will be primarily based on the 5G networks, with multiple wireless Radio Access Technologies (RATs) coexisting. The factors influencing user experience are complex and diverse, making it difficult for any single wireless technology to meet all user needs. Most existing network selection algorithms focus on either the user side or the network side, leading to the problem of network load imbalance. Therefore, this paper proposes a Multi-Attribute Synergetic Decision (MASD) algorithm for 5G integrated heterogeneous wireless network. First, implement the pre-filtering of the candidate network set. Taking into account the diversity of user services, this algorithm focuses on Quality of Service (QoS), user preferences, and network load. Analytic Hierarchy Process (AHP) and Standard Deviation (SD) are used to calculate the weights of each attribute. Based on the synergetic theory, the entropy value of the candidate network system is obtained. Simulation results demonstrate that this algorithm effectively coordinates various factors to select the most suitable network for access. It reduces unnecessary handovers, avoids the ping-pong effect, and achieves load balancing to a certain extent.

In this paper, a broadband compact dual-polarized antenna for base stations is proposed. This antenna consists of a pair of crossed dipoles, four triangular parasitic patches, four metal posts and a box reflector. The crossed dipoles are fed by two 50 Ω coaxial cables. The increase of four parasitic patches allows the resonant point to be generated at high frequencies to further widen the impedance bandwidth; the size of the parasitic patches is reduced to realize the reduction of the antenna radiator size; and the impedance matching is improved by cutting circular slots in the dipole arms. The measured results show that the proposed antenna is able to achieve a wide impedance bandwidth of 79% (1.67 to 3.87 GHz) with VSWR less than 1.6. A stable gain of 8-8.7 dBi and a half-power beamwidth (HPBW) of 60-78° are obtained at 2.2-3.65 GHz. In addition, the antenna radiator is very compact in size, only about 0.41λ_L × 0.41λ_L × 0.17λ_L, where λ_L is the longest operating wavelength.

In this article, a new design approach for an unequal coupled transmission line dual-band Wilkinson power divider is presented. A parallel short or open circuit stub is considered at the input port for dual frequency response, and two resistors are connected in order to isolate the outputs. The method is based on an even-odd mode procedure. The main objective of this paper is to fabricate a dual band Wilkinson power divider in order to achieve higher dividing ratio, simple structure, and easier fabrication. First, the desired power divider is divided to two parts known as even and odd mode equivalent circuits. Then by analyzing the circuits, the characteristic impedances are calculated. Next, the coupled transmission lines dimensions are extracted. Afterward by using the calculated characteristic impedances, an error function is formulated, and by minimizing, the isolating resistors are obtained. To clarify the applicability of this method, several microstrip power dividers which operate at both 1 GHz and 2.3 GHz with dividing ratio equal to 1.2589 are designed and simulated with the assumption that relative permittivity is equal to 2.56. In order to demonstration the advantage of using coupled lines tow dividers, one by separated-lines and the other one by coupled-lines are designed and compared with each other. The results illustrate that while the coupled-line dividers have simpler structure, they have significantly similar frequency operation to separated-line ones. Then the designed structure fabricated on an FR4 substrate and S parameters are measured. The results show excellent agreement with simulation.

A wearable dual-band patch antenna is presented, which can adjust its frequency for WBAN applications. Frequency reconfiguration is achieved by the antenna through the utilization of the switching properties of a PIN diode. Produced using a Rogers Duroid material with semi-flexible properties, the antenna has a size of 0.33λ₀ × 0.35λ₀ × 0.012λ₀. Initially resonating at 5.8 GHz, a slot in the shape of an inverted letter U is included to introduce a dual-band operation at 2.4 GHz. By controlling the PIN diode's ON and OFF states, the antenna can switch between single-band (ISM 5.8 GHz) and dual-band (ISM 2.4 GHz and 5.8 GHz) operations. The antenna exhibits a bi-directional radiation pattern at 2.4 GHz and a directional pattern at 5.8 GHz. In the ON state, the antenna achieves a peak gain and total efficiency of 4.84 dBi, 5.87 dBi, 92.5%, and 92.7% at 2.4 GHz and 5.8 GHz, respectively. In the OFF state at 5.8 GHz, a peak gain and total efficiency of 6.01 dBi and 91.8% are measured. To evaluate its suitability for WBAN applications, the antenna's performance is assessed by measuring SAR values on a human tissue model. At 2.4 GHz, the SAR values for 1/10 g of human tissue are 0.411/0.177 W/kg respectively. Similarly, at 5.8 GHz, the SAR values are 0.438/0.158 W/kg respectively. The SAR values comply with the established standards of the FCC and ICNIRP for both resonance frequencies for human tissue weighing 1/10 g. Overall, the antenna boasts a compact size, acceptable SAR values, and satisfactory gain and efficiency across all operating bands, surpassing previous works. It also benefits from a simplified design employing a single switch, and the antenna remains a suitable choice for WBAN applications considering its other advantageous characteristics mentioned above.

The variable orbit altitude and platform velocity in high-eccentricity orbit synthetic aperture radar (HEO SAR) increase the difficulty in obtaining effective radar echoes. In this letter, a new stripmap imaging mode with multi-parameter joint agile variation in HEO-SAR is proposed. First, the range side-looking angle is adjusted during the whole raw data acquisition interval according to the time-varying side-looking geometric relationship, while the pulse repetition frequency (PRF) is continuously changed to obtain uniform azimuth sampling due to the satellite velocity variation. Besides simultaneously adjusting the side-looking angle and the operated PRF, echo sampling start time and range sampling points are also continuously changed to decrease the echo data rate. According to the echo characteristics in HEO SAR, its corresponding imaging algorithm is presented, which includes range samples adjustment, azimuth resampling, cubic filtering, nonuniform Fourier fast transform (NUFFT) for nonlinear range cell migration correction (RCMC) and modified azimuth compression. A system design example with multi-parameters joint agile variation for the desired resolution of 3 m and the swath width of 30 km is given, while an imaging simulation experiments on point targets are carried out. Both simulation results of multi-parameters variation design and point targets imaging validate the proposed stripmap imaging mode with multi-parameters joint agile variation in HEO SAR.

Single-phase asynchronous motors have an irreplaceable role in small production fields such as household appliances and office equipment. However, due to the existence of small single-phase asynchronous motors with low power factor, low efficiency, vibration and noise, and other problems, the performance of a single-phase asynchronous motor, including efficiency, power factor, and vibration noise has been unable to meet the increasing needs of people. In this paper, a single-phase line-starting permanent magnet synchronous motor (SPLSPMSM) for air compressor is designed with the core size of Y series three-phase asynchronous motor for reference. The operating capacitance, the number of turns of the main stator winding, the turns ratio of the main and auxiliary windings, and the permanent magnet size are selected as optimization variables, and the efficiency, power factor, and starting torque are the optimization objectives. A regression model was developed by the response surface method (RSM) to optimize the performance of the motor, and the reliability of the response surface experiment was verified. The results show that the performance of the optimized motor is improved in terms of rated operation and starting performance.

A novel miniatured reconfigurable antenna for wireless applicationsusing defective ground structure is proposed and studied. This proposed antenna generates eight different frequencies, operating at 2 GHz (IMT), 2.3 GHz (UMTS), 2.5 GHz (Wi-Fi), 2.7 GHz (Radio astronomy), 2.9 GHz (Weather radar), 4.2 GHz (Radio altimeter), 4.4 GHz (Radio determination) and 5.5 GHz (Wi-MAX) while maintaining overall compact size of 24×33×1.6 mm³ using an FR-4 substrate having a permittivity of ε_r = 4.4. The proposed reconfigurable antenna consists of three switches in the slots of the patch along with rectangular defects on ground surface and a microstrip feed line. The lumped elements are used in place of three switches in the simulation to get tunable capacitance, which is responsible for frequency reconfigurability. It makes the antenna operate at eight useful bands. The structure shows the impedance bandwidths of 6.86%, 6.04%, 2.51%, and 2.73% with gains 5 dB, 4.8 dB, 6 dB, and 6.8 dB, respectively. The designed antenna can be easily integrated on the modern communication devices. A prototype of the designed antenna is fabricated, and simulation results are compared with measured values using PIN diode switches.

Three-dimension (3-D) images provide additional information of targets for automatic target recognition (ATR) and 3D scattering model generation. Methods based on sparse representations can reconstruct extreme resolution 3D images from sparse measurements, but suffer from the huge dimension of separable dictionaries. This paper presents a time-domain sparse representation method for 3-D target imaging from multi-view synthetic aperture radar (SAR) data, including a basic method and two improved ones. The time-domain framework uses time-domain responses to build a separable dictionary and a sparse representation model. In the time-domain framework, the basic approach is to transform the dictionary into a rather sparse matrix via a low-energy threshold that shrinks the spatial region of the 3D imaging based on multi-aspect 2D images. By exploiting the properties of multi-aspect SAR data in the time domain, one modification makes the sparse representation model more compact, leading to a reduction in dimension, and another additional modification splits a high-dimensional large-scale model into a set of very low-dimensional small-scale models. They overcome the curse of dimensionality and improve the efficiency of sparse representation-based 3D imaging to varying degrees. Experimental results show the effectiveness and great efficiency of the proposed method.

To solve the problem of mixed noise in a passive millimeter-wave (PMMW) imaging system that affects object detection, recognition, and classification, this paper proposes a blind denoising algorithm based on pixel non-local self-similarity (PNSS) prior to PMMW images. Firstly, an adaptive filtering algorithm is introduced, utilizing PNSS prior to estimating the noise intensity and improving the problem of noise residual caused by parameter uncertainty in traditional filtering processes. Secondly, a three-level joint denoising algorithm is developed, accompanied by an iterative regression algorithm to effectively filter the mixed noise in PMMW images while preserving image contours. Finally, the effectiveness of the proposed method is demonstrated through a comparison with patch similarity-based prior denoising methods and high-dimensional mixed noise denoising methods. Experimental results substantiate that the proposed PNSS blind denoising method successfully suppresses mixed noise in PMMW images, enhances subjective visual perception, and presents a novel approach for denoising under various PMMW imaging mechanisms.

Rapid and sensitive analysis of proteins in complex biological environments is crucial for the screening and defense against infectious diseases. Here, we show that the lateral flow immunoassay strip based on confocal Raman imaging can achieve immune analysis at pM and ~10⁴ cfu/mL molecular level for the rapid detection of COVID-19 virus and bacteria. Fluorescent dyes of Alexa 647 were used as Raman markers in the Raman silent region of 1800 cm^-1 and 2800 cm^-1, and colloidal gold nanospheres were used to enhance the Raman signal. Raman imaging was performed with our self-developed confocal Raman microscopy for COVID-19 and Escherichia coli O157: H7 on lateral flow immunoassay strip. Compared to traditional colloidal gold test strips, the sensitivity of this technology has been significantly improved. This work will promote the widespread application of surface enhanced Raman detection for bacteria and virus, which is of great significance for in vitro screening and disease diagnosis.

For long-range communication, the directivity and gain of a millimeter wave antenna should be high. The aim of the paper is to design an antenna array that works at higher frequencies X/Ku-band (8-12 GHz)/(12-18 GHz) respectively for applications such as RADAR. This can be achieved by an array of antennas as single antenna cannot provide such high gain and directivity. The radiation pattern has directional pencil beam in which the frequency and gain plot is shown at 11.32 GHz. The maximum gain of 29.0994 dB has been achieved at 11.32 GHz frequency. The software High Frequency Structure Simulator (HFSS) has been used for simulation, and the simulated and measured results are found in agreement with each other

In order to improve the efficiency and safety of emergency rescue operations, a wearable circularly polarized (CP) antenna suitable for GPS applications has been designed. It adopts a coplanar waveguide (CPW) feed structure, where the ground plane and radiation patch form an annular gap. The impedance bandwidth and axial ratio performance are enhanced by adjusting the amplitude and phase difference of the current distribution through two pairs of notches and open-circuit branches. When the single antenna is more than 20 millimeters away from the human body model, its CP radiation performance is acceptable, and the peak Specific Absorption Rate (SAR) also meets the required standards. To minimize the separation distance between the antenna and the human body, a 2×2 Artificial Magnetic Conductor (AMC) with in-phase reflection characteristics is integrated at the antenna's bottom as a reflector, which increases the antenna gain and reduces the SAR. Simulation and test results indicate that in the GPS L1 frequency band, the antenna achieves a gain greater than 7 dBi, an axial ratio less than 2 dB, a front-to-back ratio of 24 dB, and a peak SAR of 0.53 W/Kg, which is well below the standard limit of 1.6 W/Kg set by the Federal Communications Commission (FCC). Compared with other relevant antennas, this antenna features compact size, wide impedance bandwidth, and robust anti-interference capability, effectively improving the flexibility and compatibility of the wearable antenna, thereby meeting the demand for efficient and reliable positioning of rescuers.