A design of a series-fed antenna array without beam deterioration using miniaturized bandpass filters (BPFs) is proposed. The BPFs are connected behind branches of series feed network (SFN) to compensate the varied phase slope of paths, resulting in constant phase difference between elements across the bandwidth. Hence, the beam deterioration versus frequency is removed. The closed-form equations of the phase slopes for BPFs are deduced, and thus they can be designed quantitatively for phase slope balancing. The proposed SFN has advantages of compactness, simplicity, and low loss. For validation, an 8-element antenna array is designed and measured. The gain and sidelobe level are 12.2-12.39 dBi and 11.67-12.65 dB within the bandwidth of 5.2-5.8 GHz. As comparison, the gain and sidelobe level are 12.85-13.77 dBi and 7.18-12.75 dB using conventional feed network. Therefore, the designed antenna array has stable radiation pattern including beam direction, sidelobe level, and gain.

This paper presents a simple approach for evaluating the complex magnetic permeability of the steel fibers used in concrete according to frequency. The approach utilises the eddy current non-destructive evaluation method, where the electrical impedance is measured using a precision LCR meter and computed using a magneto-harmonic model solved in Py-FEMM software. Initially, the electrical conductivity of the steel fiber is measured using a two-contact DC method. Then, the inverse problem method is applied to identify the complex magnetic permeability. This is achieved by iteratively minimising the difference between the calculated and measured impedances using a simplex optimization algorithm. The proposed approach offers a non-contact, non-destructive, fast, and efficient procedure to evaluate the complex permeability. The obtained results provide valuable insights into evaluating the distribution of steel fibers in concrete.

The research on landslide displacement prediction can help the early warning and prevention of landslide disasters in mining areas. In view of the problem that BP neural network is prone to local convergence, and considering that the network trained based on time-series cumulative displacement may produce large errors in prediction, this paper proposes a method combining displacement increment and CS-BP (Cuckoo Search-Back Propagation) neural network to predict landslide displacement. Compared with the conventional landslide displacement prediction methods, this method uses displacement increment instead of the commonly used cumulative displacement as the network input data, and selects the CS algorithm with few parameters and easy to implement to optimize the BP network to construct the prediction model, and predicts the corresponding amount of displacement change at the next moment by the historical landslide displacement increment. Combined with the measured data of three feature points of a mine in Xinjiang, China, obtained by the micro-deformation monitoring radar, the displacement prediction accuracy of the proposed model on the three measured data sets is compared with the prediction accuracy of the BP, GA-BP (Genetic Algorithm, GA), and FA-BP (Firefly Algorithm, FA) network prediction models based on cumulative displacement and incremental displacement, respectively. The experimental results show that this method achieves superior performance with an average root mean square error of 0.3261 and an average mean absolute error of 0.2785 across the three feature points, outperforming the other models, and holds promising applications in disaster prevention and control work.

This article presents a miniaturized octa-port high gain multiple-input-multiple-output (MIMO) antenna loaded with an electromagnetic band gap (EBG) layer for the use in 5G wireless communication applications. Each resonator of the presented antenna is comprised of a rectangular-like patch with truncated side edges and a partial ground plane. A layer of EBG unit cells is introduced underneath the antenna elements to increase the gain and restrain the surface wave effects, obtaining improved isolation amongst the resonating elements. The -10 dB impedance bandwidth of the prospective antenna with EBG is 12 GHz (21-33 GHz), and it provides isolation of >28 dB. The peak gain of the EBG-backed antenna is 17 dB. The presented mm-wave MIMO antenna offer decent diversity proficiency metrics like envelope correlation coefficient (<0.36), diversity gain (~10 dB), and total active reflection coefficient (-24.75 dB). The overall size of the octa-port MIMO antenna is 27.2 mm × 27.2 mm. The presented MIMO antenna could be used for n257/n258/n261 mm-wave bands.

In standard measurement methods such as NSA 94-106, the low-frequency magnetic shielding effectiveness of a shielding enclosure is tested using the near field of loop antenna. Under this near-field configuration, there is no analytical or closed-form solution for volumetric shielding like box/cavity except for planar shielding like a sheet of infinite extension. Exploring the correlation between volumetric shielding and planar shielding can provide simple prediction methods for volumetric shielding based on planar shielding. As a taste to this end, this article explores the difference between the shielding effectiveness of a double-sheet cavity and a single sheet under the NSA 94-106 standard. We derived the exact solution in integral form for electromagnetic fields inside the cavity and calculated the curves of shielding effectiveness on the frequency with different sheet material, thickness, and sheet-to-sheet distance. The results show that when the distance from the receiving antenna to the back sheet is greater than the diameter of the loop antenna, the results of a double-sheet cavity tend to be consistent with a single-sheet configuration. When the distance is less than the diameter, the difference between the two depends on material type and sheet thickness.

A novel microstrip loop-type resonator with four resonant modes is proposed in this letter. The resonator is formed by a loop-type microstrip line loaded with four shorted stubs. It has a symmetrical structure, thus the odd-even-mode method is adopted to implement the resonant analysis. The novelty of the proposed resonator lies in two aspects. One is that its resonant frequencies can be adjusted in a more flexible way. The other is that its resonant modes have a uniform electromagnetic field distribution, which is beneficial for the excitation of resonant modes. For the purpose of demonstration, based on the novel resonator, a single-band bandpass filter with four transmission poles and a dual-band bandpass filter with two transmission poles in each passband are constructed. Additionally, source-load cross coupling is introduced, and several transmission zeros are generated in the stopband, which improves the out-of-band performance greatly. The designed single-band filter has the central frequency of 2.4 GHz and fractional bandwidth (FBW) of 4.5%, and the dual-band filter has the central frequency of 1.8/2.4 GHz and fractional bandwidth of 2.0%/2.5%. The two bandpass filters are designed, fabricated, and measured. Agreement between the simulated and measured results verifies the effectiveness of the proposed resonator and filters.

Using realistic classical models of microscopic electric-charge electric dipoles and electric-current (Amperian) magnetic dipoles, it is proven that the Einstein-Laub macroscopic electromagnetic force on a macroscopic-continuum volume of these classical dipoles equals the sum of the microscopic electromagnetic forces on the discrete classical dipoles in that volume. The internal (hidden) momentum of the discrete Amperian magnetic dipoles is rigorously derived and properly included in the determination of the macroscopic force from the spatial averaging of the microscopic forces. Consequently, the Abraham/Einstein-Laub rather than the Minkowski macroscopic electromagnetic-field momentum density gives the total microscopic electromagnetic-field momentum in that volume. The kinetic momentum is found for the volume of the macroscopic continuum from Newton's relativistic equation of motion. It is shown that the difference between the kinetic and canonical momenta in a volume of the macroscopic continuum is equal to the sum of the ``hidden electromagnetic momenta'' within the electric-current magnetic dipoles and within hypothetical magnetic-current electric dipoles replacing the electric-charge electric dipoles in the classical macroscopic continuum. To obtain the correct unambiguous value of the force on a volume inside the continuum from the force-momentum expression, it is mandatory that the surface of that volume be hypothetically separated from the rest of the continuum by a thin free-space shell. Two definitive experiments performed in the past with time varying fields and forces are shown to conclusively confirm the Einstein-Laub/Abraham formulation over the Minkowski formulation.

High Frequency Transformer (HFT) acts as the key element of a Solid State Transformer (SST), which is a mandatory equipment in smartgrid system. SST replaces power frequency transformer by providing control and communication in power system. The design of an HFT matching the design of conventional distribution transformer is done in this paper. It is done by developing an iterative algorithm using Brute Force technique. The optimum design is selected by taking minimization of total owning cost as objective function. The algorithm takes eight design variables and four design constraints for shortlisting the optimum design. The optimum design developed is validated in finite element analysis software. The multi-physics analysis of the design is done by interconnecting electromagnetic, mechanical, thermal, and power electronics components of the system. The analytical and numerical analysis follow the same pattern by conducting a case study on the design of HFT with ratings 1000 kVA, 11 kV/415 V, three phases.

A broadband high gain antenna based on metasurface is proposed in this paper. The antenna consists of two layers, the lower layer is a square dielectric plate of 64 mm × 64 mm fed by aperture coupling which brings resonance frequencies closer to each other to improve bandwidth. The upper layer is a substrate of the same size, and the substrate is covered with a metasurface composed of 4×4 triangular slots. The impedance bandwidth is expanded by introducing the metasurface from 6.7% of the single-fed antenna to 23.8%, and the overall height of the antenna is 7 mm. The antenna is excited by an aperture coupled structure consisting of a microstrip line on the back and a narrow slot etched on the ground surface. The impedance bandwidth of the proposed antenna is 23.8%, ranging from 4.8 GHz to 6.1 GHz. The peak gain at 5.6 GHz is about 11.2 dB, and the gain is relatively stable throughout the entire operating frequency band. An antenna prototype is made, and the measurement results verify the design's correctness.

An analytical modeling method for heterojunction bipolar transistor (HBT) is proposed in this paper. The new neuro-space mapping (Neuro-SM) model applied to DC, small signals and large signals simultaneously consists of two mapping networks, which provide the additional degrees of freedom.Sensitivity analysis expressions are derived to accelerate the training process. When the non-linearity of device is high, or the response of the model is complex, the weights in the proposed model are automatically adjusted to address the accuracy limitations. The proposed modeling method is verified by measured HBT examples in DC, smallsignals and largesignals Harmonic Balance (HB) simulation. The modeling experiments of the measured HBT demonstrate that the errors of the proposed Neuro-SM model are less than 2% by matching combined DC, small-signal S-parameters and large-signal HB data, which are less than the errors of the traditional Neuro-SM model and the coarse model. The proposed analytic Neuro-SM model fits the response of the fine model well.

A novel substrate-integrated waveguide (SIW) dual-mode cavity bandpass filter with loaded defected ground structure (DGS) is proposed. The SIW dual-mode cavity operates in two modes, TE₁₁₀ and TE₁₂₀, and the field distribution of the TE₁₁₀ mode is altered by installing a metal perturbation aperture in the middle of the cavity to bring its resonance frequency close to that of the TE₁₂₀ mode, thus forming a bandpass filter with two resonance points in the passband. A DGS structure is embedded at the ground level of the SIW to introduce a transmission zero in the high-frequency rejection band, thus improving the rejection performance of the filter for the high-frequency rejection band. The simulated and measured results show that the center frequency of the filter is 3.75 GHz; the 3 dB bandwidth is 0.3 GHz; the relative bandwidth is 8%; the return loss is less than -15 dB; and the insertion loss in the passband obtained from the simulation is about -0.35 dB, while that obtained from the measurement is 0.4 dB lower than that of the simulation, and the filter has a transmission zero near the high-frequency stopband of 6 GHz, which enables the high-frequency parasitic passband to move away from the passband of the filter. Except for the passband, all other signals in the Sub-6 GHz band can be effectively suppressed by the filter. This design combines the SIW dual-mode cavity with the DGS structure to design the filter, which can realize the flexible adjustment of bandwidth and transmission zero point, and the design method is simple and innovative. The filter can be applied to the 5G n77 frequency band, which has certain application value.

A parameter identification method based on an improved hunter prey algorithm is proposed to address the issues of poor accuracy and speed in traditional permanent magnet synchronous motor parameter identification methods. By using the Fuch infinite folding chaotic strategy to evenly distribute the initial individuals to enrich their diversity and using the golden sine algorithm to optimize the population search path, the algorithm's local development ability and global search ability are improved. The reasons for the dead time effect of the inverter are analyzed, and the input voltage is compensated for through the rotation coordinate method. SIMULINK simulation and physical experiment indicate that the improved algorithm has faster rate of convergence and higher recognition accuracy than the unmodified algorithm, and can effectively identify motor parameters. On this basis, adding dead time compensation effectively eliminates partial harmonics of the phase current and suppresses the occurrence of zero current clamping phenomenon. Compared with the situation without dead time compensation, the identification error of the four parameters has decreased from below 4.23% to below 2.21%.

This paper presents the design of a planar tunable Negative Group Delay (NGD) circuit with low reflections. A pulse-shaped stub inscription on the signal strip of a microstrip line generates a negative group delay, which can then be tuned to a desired value by varying the resistance inside the inscription. Poor reflection characteristics are inherent in such circuits, and a conventional solution like a simple impedance matching circuit compromises the overall NGD performance for a reduced reflection loss. Here, we have included a novel impedance-matching network loaded with absorptive elements at the input/output ports to avoid any reflections from the circuit, while maintaining its NGD behavior and compactness. The measured results validate the proposed design with -5 ns GD at 3 GHz with less than -10 dB reflection loss over the whole NGD bandwidth of 228 MHz at 3 GHz.

The quantum illumination radar uses pairs of entangled photons to enhance the detection sensitivity of a reflecting target. In this paper, we worked on a quantum illumination radar using a pair of entangled photons in polarization in the microwave frequency range in the atmosphere. We studied the quantum information evolution modeling the propagation of a photon in the atmosphere while building two binary decision strategies for the QI radar. We focused on the quantum information evolution showing that the quantum discord representing quantum correlations beyond entanglement could represent an interesting resource to explore for the subject of quantum radar. In addition, we made an approximative estimation of the entanglement survival distance in the atmosphere. Results showed that an optimization should be found to favour the survival of quantum correlations or the signal-to-noise ratios calculated with the binary decision strategy.

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.