A design of a modified bow-tie slot loaded wideband antenna using a Substrate Integrated Waveguide (SIW) cavity is proposed in this paper. The simple bow-tie slot perturbs the current distribution of the TE₁₂₀ mode, which generates two hybrid modes, namely odd TE₁₂₀ and even TE₁₂₀ modes at 9.6 GHz and 10.8 GHz respectively, but the achieved bandwidth is only 500 MHz (5.2%). To increase the bandwidth, a short rectangular slot is incorporated at the middle of the bow-tie slot, which moves the hybrid odd TE₁₂₀ mode to 10.2 GHz, near even TE₁₂₀, which helps to achieve a wide bandwidth of 1.1 GHz ranging 9.9 GHz-11 GHz (10.5%), and also it exhibits a unidirectional radiation pattern. The proposed antenna is fabricated for experimental validation of the modified bow-tie slot antenna. The measured value of bandwidth is 1.1 GHz from 10.1 GHz to 11.2 GHz (10.3%) with a consistent gain of 6.25 dBi, and the variation between co-pol and cross-pol is maximal. Because of the wide bandwidth, high gain and compactness, the suggested antenna is suitable for satellite, radar, and all practical wireless applications of X-band frequencies.

A high performance substrate integrated waveguide (SIW) slotted array antenna with low sidelobe level and optimum gain at 28 GHz is designed, and experimental results are presented with simulated data. In order to achieve a low sidelobe level, Chebyshev power coefficients in the form of slot displacements are applied to the SIW array antenna. A MATLAB program has been written to find these slot displacements. This work entails investigating and designing the optimum microstrip to SIW transition over the Ka-Band, designing a 1 x 8 slotted SIW array antenna, and finally applying the Chebyshev power coefficients to the slots of the 1 x 8 SIW array antenna. The fabricated prototype of a 1 x 8 SIW slotted array antenna is tested, and its performance is studied in terms of gain and half power beam width (HPBW), compared with simulations. The measured results of the 1 x 8 slotted SIW array antenna at 28 GHz have a |S₁₁| of better than -20 dB, a gain of 13 dB, and an HPBW of 17˚. The overall dimensions of the design at 28 GHz are 7.143 mm x 51.8 mm x 0.254 mm (0.667λ_o  ×  4.84λ_o ×  0.023λ_o = 0.0766λ_o³ mm³).

This article proposes a compact dual-band circle-shaped implantable antenna for scalp and skin implantation applications. The proposed antenna covers the 1.395-1.432 GHz Wireless Medical Telemetry Service (WMTS) band and 2.4-2.48 GHz Industrial, Scientific, and Medical (ISM) band with a compact volume of 0.0000017λ₀³. The antenna maintains a realized peak gain of -24.5 dB and -20.6 dB, respectively, at 1.43 GHz and 2.44 GHz. Moreover, the gain pattern of the antenna is in the off-body direction which is a desirable feature for implantable scenario. It also depicts stable responses under different implantation scenarios. Moreover, the via free configuration is an advantageous feature of the proposed antenna in the context of fabrication complexity. Furthermore, a holistic design approach is considered with integrated components for device-level architecture. The resonance behavior of the proposed antenna structure is also analyzed by developing a conceptual equivalent circuit model. The evaluated specific absorption rate (SAR) complies with the regulated human safety standard. The biotelemetry link capability is also evaluated through the link margin (LM) calculation of the proposed antenna and is able to establish a communication link at a range of 4.5 m distance.

In this work, the mask-constrained synthesis of domino-tiled phased arrays is addressed. By exploiting tiling theorems and theory, optimal and sub-optimal methods for the synthesis of domino arrangements and the corresponding excitations that minimize the deviation of the radiation pattern from a user-defined power mask are presented. A set of numerical examples, carried out with full-wave simulators and concerned with different aperture sizes and various mask shapes, is reported to assess the effectiveness, limitations, and ranges of computationally-admissible applicability of the proposed methods.

In order to solve the problems of high THD (total harmonic distortion) of air-gap magnetic density, large cogging torque and low power density of permanent magnet (PM) hub motor, a built-in tangential and radial PM combined-pole hub motor is proposed in this paper. The magnetic field provided by tangential PM is the main magnetic field, and the magnetic field provided by radial PM plays an auxiliary role in regulation, which can effectively improve the air-gap magnetic density of the motor, reduce the THD of back electromotive force (EMF), and weaken the peak value of cogging torque. Based on the equivalent magnetic circuit method, this paper analyzes the magnetic circuit of the motor, deduces the leakage magnetic flux coefficient, and reduces the leakage magnetic flux by optimizing the structure of the motor. Finally, the prototype is manufactured and tested to verify the effectiveness of finite element analysis. The results show that the designed PM hub drive motor has low THD of back EMF and good sinusoidality of waveform under no-load condition, and good output performance.

In order to effectively improve filter selectivity and out-of-band rejection level, a multi-cavity two-mode dual-passband filter operating in X-band is proposed. By designing a suitable circuit topology, the bandpasss of the filter are formed using TE₂₀₁ mode in the substrate integrated waveguide (SIW) cavity and the TE₁₀₁ mode in the half mode substrate integrated waveguide (HMSIW) cavity. In addition, incorporating a T-slot structure in the dual-mode SIW cavity can add additional transmission zeros (TZs) and improve the filter selectivity while achieving miniaturization. The center frequencies of the two passbands are 8.67 GHz and 11.52 GHz, respectively. The inter-band isolation is better than 65 dB with three transmission zeros and maximum insertion loss of 0.48 dB and 0.31 dB, respectively. The proposed filter has a compact structure, low insertion loss, high-frequency selectivity, and the measured results agree with the simulated ones.

High torque and power generating capability of double-stator axial flux switched reluctance motor (DSAFSRM) makes it superior to conventional and segmented rotor switched reluctance motors. Despite its significant feature, the ripple in developed torque still limits the usefulness of DSAFSRM for widespread industrial application. This paper proposes anj 8/6/8 pole DSAFSRM with modification in rotor pole shape to reduce torque ripples in respective model. The respective phase windings of the upper and lower stators are excited externally by preparing the circuit in Maxwell software. Each rotor tooth is constructed with two types of slots with different levels of air gap to change the inductance profile. Firstly, the design of a conventional DSAFSRM has been presented; thereafter, some geometric modifications in the rotor tooth have been suggested and investigated to obtain a lower torque ripple at 1200 rpm in proposed DSAFSRM. The efficacy of the proposed motor is investigated through finite element method (FEM) based analysis and also by comparative analysis with other types of switched reluctance motors. It can be inferred from the simulation results that the torque ripple is significantly reduced by 111.16% in the proposed DSAFSRM compared to the conventional DSAFSRM. However, the efficiency of the proposed DSAFSRM (73.87%) is slightly less than the conventional DSAFSRM (74.65%).

To rapidly simulate the forward electromagnetic scattering of multiple obstacles, we propose a new forward scattering prediction model, which can effectively simulate the propagation of electromagnetic waves in a large-scale environment, accurately calculate the scattering of multi-scale structures, and realize multi-region parallel computation. Specifically, the proposed model consists of an obstacle region and a large-scale environment region. To make the model consistent with the real scene quickly and accurately, the time-domain parabolic equation (TDPE) and the discontinuous Galerkin time-domain (DGTD) method are employed to simulate the propagation of electromagnetic waves and the scattering of obstacles, respectively. At the same time, each region is equivalent to a linear time-invariant (LTI) system, and the transfer function of each system is calculated by the discrete Laplace Z-transform to realize multi-region parallel computation. This model can simulate the propagation of the electromagnetic wave in multiple obstacles more quickly under large-scale background than the existing obstacle forward scattering model. Numerical results demonstrate that the proposed model is effective in terms of accuracy and runtime performance.

In this paper, a novel flexible antenna for the new ISM band is proposed. A multi-objective optimization based on DDEA-SE is performed to optimize the antenna bandwidth and gain. The proposed optimized antenna has a 4 dB maximum realized gain and 50% maximum radiation efficiency on the ISM band. A fractal structure is used in this design to achieve a multi-band antenna. The bandwidth of this antenna covers several 5G bands. This multi-band antenna is fabricated on a cotton substrate. This antenna has a small dimension which makes it suitable for 5G applications. The bending tests are performed, and both simulation and measurement results show the good performance of the proposed antenna.

A compact bandpass filtering antenna operating at 5.1 GHz is introduced. The radiation layer makes up of a U-shaped patch and a trident resonator. The U-shaped patch is both the antenna and the last stage of the filter, which is excited by the insertion coupling part of the trident resonator. To improve the impedance matching and lower stopband suppression, a defective ground structure (DGS) is used. The dimension of the antenna is 0.36λ₀×0.36λ₀×0.01λ₀ (λ₀ is the wavelength at 5.1 GHz) without a complex external feed structure, which has enough bandwidth, a good frequency skirt selectivity, and a flat passband response. The measurement results manifest that the impedance bandwidth is 110 MHz, and the peak gain is 3.88 dBi. In addition, the filtering antenna also has a sharp roll-off rate and a satisfactory level of out-of-band suppression in the stopband.

Exact solutions to Maxwell equations with topological charge based on a modification to Brittingham's single cycle pulses are analyzed demonstrating that they have finite values of energy, momentum and angular momentum. Moreover, the ratio of angular momentum to energy is bounded due to the dependence of the mean frequency on topological charge. We have also analyzed the skyrmionic texture of the electric and magnetic fields showing that it is possible to obtain skyrmionic numbers higher than one for the magnetic field by means of a superposition of pulses with different topological charges and null skyrmionic number.

The limited space of the substation contains a lot of electrical equipment and voltages ranging from hundreds to several thousand volts, resulting in a complex electromagnetic environment in the substation. As the deployment of 5G base stations increases in substations in China, the power-frequency magnetic field in substations will cause problems, resulting in a location problem. This paper develops a circuit model for converter stations, and presents a calculation method that considers the geomagnetic permeability, 3-phase transmission mode, and erection direction influences. The correctness of the calculation method in this paper is verified by comparing the simulation results and calculation results of the substation model. The deployment conditions of 5G base stations in the substation are analyzed according to the national standard of the requirement and measurement methods of electromagnetic compatibility for mobile telecommunications equipment Part 17: 5G base station and ancillary equipment.

⋅A p-adaptive discontinuous Galerkin time-domain method is developed to obtain high-order solutions to electromagnetic scattering problems. A novel feature of the proposed method is the use of divergence error to drive the p-adaptive method. The nature of divergence error is explored, and that it is a direct consequence of the act of discretization is established. Its relation with relative truncation error is formed which enables the use of divergence error as an inexpensive proxy to truncation error. Divergence error is used as an indicator to dynamically identify and assign spatial operators of varying accuracy to substantial regions in the computational domain. This results in a reduced computational cost compared to a comparable discontinuous Galerkin time-domain solution using uniform degree piecewise polynomial bases throughout. Numerical results are presented to show performance of the proposed divergence error based p-adaptive solutions. It is shown that an accuracy similar to that of uniformly higher order solutions is obtained in terms of the scattering width, using fewer degrees of freedom.

A deep learning linear sampling method (DLSM), composed of linear sampling method (LSM) and a convolutional neural network (CNN) of U-Net, is proposed to restore shape of multilayered scatterers with cylindrical or rectangular cross section. Simulations over random samples with different geometrical parameters are used to verify the efficacy of the proposed method.

In this paper, we present an efficient numerical method to calculate the frequency and time responses of the field scattered by an object buried between two random rough surfaces for a 2-D problem. This method is called Generalized PILE (GPILE) method because it extends the PILE method which considers only two surfaces or an object buried under a surface. The GPILE method solves the Maxwell equations rigourously by using a simple matrix formulation. The obtained results have a straightforward physical interpretation and allow us to investigate the influence of the object buried between the two rough surfaces. We distinguish the primary echo of the upper surface, the multiple echoes coming from the lower surface and those arising from the object. The GPILE method is applied to simulate the Ground Penetrating Radar (GPR) signal at nadir. The resulting time response helps the user to detect the presence of the object buried between the two random rough surfaces.

Photonic integrated circuits (PICs) and microwave integrated circuits (MICs) have been widely studied, but both of them face the challenge of miniaturization. On one hand, the construction of photonic elements requires spaces proportional to wavelength, and on the other hand, electromagnetic compatibility issues make it challenging to reach high-density layouts for MICs. In this paper, we review the research advances of miniaturized PICs and MICs based on surface plasmon polaritons (SPPs). By introducing SPPs, miniaturized photonic elements at subwavelength scales are realized on PICs, which can be used for highly integrated interconnects, biosensors, and visible light wireless communications. For MICs, since the metals behave as perfect conductors rather than plasmonic materials at microwave frequencies, plasmonic metamaterials are proposed to support spoof SPPs. Spoof SPPs possess similar characteristics to SPPs and can be used to realize high-density channels on MICs. Moreover, combining the latest theoretical research on SPPs, future tendencies of SPP-based MICs are discussed as well, including further miniaturization, digitization, and systematization.

To improve the performance (low torque ripple, high average torque and high efficiency) of the external rotor switched reluctance motor (ERSRM), a preference multi-objective optimization framework for design and control of an ERSRM based on CD-NSGA-II (Chi-square distance fast non-dominated sorting genetic algorithm) with gradient targets is investigated. Firstly, the structure of the ERSRM is introduced, and the comprehensive sensitive analysis that evaluates the influence of each design variable on optimization objectives is presented. Secondly, the initialization of population, cross-mutation method and sorting method of conventional NSGA-II are improved. Then, the practicability of this method was proved by standard test functions. Finally, the NSGA-II and CD-NSGA2-II are combined with the visual basic script (VBS) script to optimize the ERSRM, respectively. Finite-element analysis results confirmed the validity and superiority of the optimized design.

Benefit from the high resolution, penetrating and all weather advantages of millimeter-wave (MMW) imaging, MMW imaging plays an important role in remote sensing, security inspection, navigation, etc. Among the MMW imaging systems, synthetic aperture imaging radiometer (SAIR) utilizes aperture synthetic technology to achieve higher imaging resolution, but the perception information is insufficient, resulting in poor image quality. In order to improve the image quality of passive SAIR MMW image effectively, we propose a novel multichannel depth convolutional neural network (MDCNN) in this paper. Aiming at the characteristics of original MMW images with more noise in low-frequency information and less features in high-frequency information, wavelet transform is incorporated into the MDCNN to obtain the high and low frequency components firstly. Then, dense residual block and skip connection technology are adopted to denoise and enhance target information in the four independent channels respectively. Finally, high quality MMW images are synthesized by inverse wavelet transform. The simulation results show that the reconstructed images of MDCNN have better image quality (such as image contour and texture details) than other deep learning-based methods.

In order to obtain the analytical expression of the position of sparse array sensors under the condition of a given total array sensor number, a sparse array design method based on direct-connection of 4 uniform linear arrays (DCUA4) is proposed. By using the only known parameter of the total array sensor number, the sensor number and spacing parameters of four subarrays are obtained by mathematical operation, then the four subarrays are directly connected to realize the design of sparse array. It is proved that the aperture of the sparse array is large, and there are no holes. Because all the sensors are allocated to four subarrays, the number of small spacing sensor pairs in the array is controlled The performance of the proposed array is simulated based on the spatial smoothing MUSIC (SS-MUSIC) algorithm. The simulation results show that the proposed DCUA4 can produce a large virtual array aperture, realize high-precision direction of arrival (DOA) estimation under underdetermined conditions, and resist the influence of low mutual coupling.

The growing interest in collision avoidance automotive radar systems in K-band necessitates the development of dedicated antenna systems with 45˚ inclined linear polarization (LP). In this letter, a 45˚ inclined LP array antenna with Taylor distribution is proposed, designed, and fabricated.