A novel integrated compact antenna with photonic band gap (PBG) structure, having switching capability between lower and upper bands of 5G cellular communication is proposed. The proposed antenna can operate in the lower band (3.1 GHz to 3.5 GHz) as well as in the upper band (24 GHz to 27 GHz) of 5G cellular communication. Two radiating patches for the aforementioned frequency bands are developed in the same structure. A small patch for the upper-frequency band is inserted into a rectangular slot made in a large patch of the lower-frequency band. Both patches radiate at different times with the same ground. Two PIN diodes have been used to excite both patches at different times. The results indicate that the antenna has higher gain and wider bandwidth than the conventional antenna without a PBG structure.

This paper presents a 90° broadband compact phase shifter which employs loade λ/2 transmission line. By adding an H shaped open stub loaded transmission line, the bandwidth of the phase shifter is broadened. Detailed theoretical analysis and circuit configuration are presented to explain the mechanism. The proposed phase shifter is fabricated and measured to validate the design principle. The simulated and measured results show that the proposed phase shifter achieves 6.6 to 19.4 GHz bandwidth with low phase instability ±5°, very low insertion loss (0.3 dB in 7.5-15.2GHz), high return loss (10 dB), and a compact size (5.8cm*6.1cm). Good agreements are observed between the measured and simulated results with small phase deviation. Moreover, the configuration of the proposed phase shifter is simple in both design and fabrication which makes the design suitable for actual applications.

The study of the electromagnetic field, taking into account eddy currents in the conductive half-space, is based on the exact analytical solution of the general three-dimensional quasi-stationary problem. The mathematical model includes an approximate solution using asymptotic expansion in the case of strong skin effect. Analytical expressions are obtained for the electric and magnetic fields at a flat interface in the form of limited asymptotic series, each term of which is expressed through a known field of external sources. The expressions take into account the nonuniformity of the field near the surface, since they contain its derivatives with respect to the coordinate. The series expansion was carried out according to a small parameter, which is proportional to the ratio of the field penetration depth to the distance between the interface and the sources of the external field. The found expressions generalize the approximate boundary impedance condition for the case of the penetration of nonuniform electromagnetic field into conductive medium.

A time domain hybrid method is presented to solve the coupling problem of non-parallel transmission lines (NPTLs) excited by ambient wave efficiently, which consists of transmission line (TL) equations, finite-difference time-domain (FDTD) method, and interpolation techniques. In this method, NPTLs are firstly divided into multiple independent transmission line segments according to the FDTD grids. Then the TL equations are applied to build the coupling models of these TL segments, which rely on the calculation precisions of per unit length (p.u.l) distribution parameters of NPTLs and equivalent sources of TL equations. Thus, the p.u.l parameters of NPTLs are derived from empirical formulas, and the equivalent sources are obtained by some linear interpolation schemes of electric fields on the edges of FDTD grids. Finally, the difference scheme of FDTD is utilized to discretize the TL equations to obtain the voltages and currents on NPTLs and terminal loads. The significant feature of this hybrid method is embodied by its synchronous calculations of space electromagnetic fields and transient responses on NPTLs in time domain. The accuracy of this presented method is testified by the numerical simulations of plane wave coupling to NPTLs on the ground and in the shielded cavity by comparing with FDTD-SPICE method and CST software.

In this paper, a joint two dimensional (2D) direction of departure (DOD) and 2D direction of arrival (DOA) strictly noncircular (NC) unitary estimation of signal parameters via rotational invariance techniques (ESPRIT) method is proposed for an L-shaped bistatic multiple input multiple output (MIMO) radar. In the case that the incident signals are NC signals, we first utilize the received data vector and its conjugate counterparts to construct a new data vector, and then the unitary ESPRIT method is adopted to estimate the 2D-DODs and 2D-DOAs, which can automatically pair the four dimensional (4D) angle parameters. Simulation results are included to verify the effectiveness of the proposed algorithm.

In electronic beam scanning, the number of phase shifters is an obvious challenge. So, there are several methods to reduce the number of phase shifters. The aim of this paper is to investigate the use of the meta-heuristic algorithm to lower the grating lobe level in the subarray antenna. Improve the result obtained by group subarray optimization techniques to determine topology and space between elements, and complex optimization of weight, simultaneously. Uniform subarray and random subarray are analyzed in Matlab to determine the coefficient of excitation by the evolutionary algorithm, as well as swarm and hybrid. The results of the simulation are shown; this method leads to radiation pattern without grating lobe in wide scanning angle. It indicates that there is a possibility of obtaining wide electronic scanning with minimum number of phase shifters and improving result.

Petri net is a mathematical and graphical tool used for analyzing the properties of parallel and concurrent system designs. Here, it is used for checking the process modeling of 4 × 4 Butler matrix fabricated on Rogers RO3210 and resonating in Ku band. Butler matrix is well suited for satellite and aircraft antenna applications as a feeding network for phase array systems. So, this basic feed design process of antennas is studied using Petri nets for better understating the designing process and removal of any deadlocks occurring during designing and feeding of antennas. It is accomplished by analyzing the behavioral and structural properties of Petri nets. A Butler matrix divides the power amplitude into four equal parts and provides a progressive phase difference of 45˚. Therefore, its components, 0 db coupler, 3 db coupler, and phase shifters, have also been designed and simulated. After designing the components, firstly these components are joined to form a matrix design which is simulated and fabricated in ANSYS HFSS. Secondly, the designed structure is analyzed for structural and behavioral properties using Petri net's graphical and mathematical properties. After analyzing the process, the feed design can be modified further according to user requirements, and deadlock can be removed by checking the difference between the simulated and measured results of design. Likewise, here the matrix has been compared and found to be following the same pattern. The overall size of the matrix is 5.58 × 7.43 cm², which is further suitable for the user's feeding requirements and applications.

The bearingless switched reluctance motor system based on active disturbance rejection control has good anti-interference performance and robustness, but it is easy to lose stability due to the influence of measurement noise in actual engineering. The main reason for the sensitivity of active disturbance rejection control to noise lies in the noise amplification of its extended state observer. To solve this problem, a novel reduced-order extended state observer based on predictive linear tracking differentiator is proposed. First, the general form of the observer is given, and then active disturbance rejection controller is designed based on suspension system of the hybrid excitation bearingless switched reluctance motor. The suspension force is used as the hysteresis loop to eliminate the estimation of the disturbance feedforward gain, and the stability of the control system is analyzed by Lyapunov equation. Finally, the simulation comparison is conducted through Matlab. The results show that this method can effectively suppress the influence of measurement noise and reduce the error of disturbance estimation when the observer is in a low bandwidth.

Frequency selective surface is a key component in applications such as communication antenna and remote sensing radiometer. One of the core parameters is selectivity, which is usually realized using a multi-layer structure or through a complicated 3D structure. These methods, however, would impose much challenge on alignment or fabrication. This paper proposes a single-substrate and combined-united array to realize a high selectivity frequency selective surface. The unit cell is a combined pattern of cross dipole and square loop to generate double transmission zeroes out of the passband. Both sides of the substrate are printed with the same pattern to enhance the selectivity. Such a structure enables easy fabrication and assembly by avoiding using multi-substrates. A prototype in the Ku-band demonstrates that both sides of the passband show high selectivity.

In recent years, deep learning (DL) is becoming an increasingly important tool for solving inverse scattering problems (ISPs). This paper reviews methods, promises, and pitfalls of deep learning as applied to ISPs. More specifically, we review several state-of-the-art methods of solving ISPs with DL, and we also offer some insights on how to combine neural networks with the knowledge of the underlying physics as well as traditional non-learning techniques. Despite the successes, DL also has its own challenges and limitations in solving ISPs. These fundamental questions are discussed, and possible suitable future research directions and countermeasures will be suggested.

This paper presents new ways of modelling several types of faults that can be encountered while monitoring cables throughout their lifecycle. These models comply with the traditional RLGC representation of a transmission line, which makes them easily usable for numerical simulations in frequency-domain. Theoretical fault signatures will then be extracted in Y. J., J. Powers, T. S. Choe, C. Y. Hong, Etime-domain to provide a better way of analyzing plots given by traditional devices, like time domain reflectometers (TDR). This allows a more accurate assessment of a cable's health and condition. It will be shown in particular that some faults can be detected even if their damaged zone remains small compared to the wavelength. A direct benefit from this is that very expensive high frequency tools are not always necessary to detect these faults. The general objective of this paper is to improve fault location accuracy by combining measurement and simulation. It will be shown how this combination can become a powerful tool to detect, locate and characterize a defect in a cable. The suggested models can be applied to any type of cable, from a coaxial line to a multi wire harness. In this work, a focus has been put on civil and military aircrafts, but similar cables are also found in cars or nuclear power plants for instance.

To explore the problem that the frequency characteristics of a magnetically coupled three-coil wireless power transfer (WPT) system are affected with different positions, in this paper, the expressions of the resonant frequency and the frequency corresponding to the maximum output power are deduced based on equivalent circuit theory. It is concluded that not only the resonant frequency is changed with different positions, but also the frequency corresponding to the maximum output power is changed with different positions. The WPT system always features a maximum efficiency point and a maximum output power point. The frequencies of the two points are almost the same. Finally, a three-coil experiment setup is built, and experimental results are well consistent with calculation and simulation results, which verifies the correctness of the proposed method. Proposed method provides a feasible scheme for simultaneously achieving high efficiency and high output power, and also provides a useful reference for the further research on the frequency tracking and optimization control algorithms.

In this paper, the problem of determining the depth and radius of a circular pipe along with the soil characteristics is studied, using electromagnetic waves with a fuzzy support vector machine as well as a fuzzy support vector machine. To this end, three neural network based fuzzy support vectors are used to determine the soil, depth and dimensions. Also, using the 2D time domain numerical simulations of electromagnetic field scattering, along with MATLAB software, 1030 data are generated for training as well as neural network verification. Given the fact that for each of the three parameters the nature of the problem is different, separate neural networks are considered with different parameters, thus the number of different data for the network training is considered. In all three cases, the neural network parameters are optimized using genetic algorithm to reduce the error and also reduce the number of support vectors. It should be noted that the objective function of the genetic algorithm consists of two components of the error, as well as the number of membership functions, which can be determined by determining a control parameter. For soil permittivity, the algorithm can accurately predict 93% of permittivities, and it decreases to 89.8 for the pipe depth determination. For diameter it is seen that for 69.3 of the cases the algorithm can correctly classify the pipes.

A wideband resonance-based reflector (RBR) is proposed in this paper. It has an in-phase reflection band from 2.61 GHz to 5.59 GHz (72.68%), while high reflection magnitude is also obtained in the band. The proposed RBR was applied to an elliptical monopole antenna, and then, the omnidirectional radiation patterns are transformed to be unidirectional ones. The antenna profile is only 0.12λ. The proposed antenna has a measured impedance band of 2.12 GHz to 6 GHz (95.57%), and a measured front-to-back ratio band (FBR > 10 dB) of 2.2 GHz to 4.68 GHz (72.09%). The maximum FBR is up to 27.21 dB, and the antenna has good radiation performances. In addition, the proposed antenna is applied to investigate the electromagnetic characteristics of a human head. The transmission characteristics of electromagnetic wave in human head and the interactions between the human head and the electromagnetic wave were studied. The field distribution and specific absorption rate (SAR) are also discussed. Research found that the antenna matched well with the human head as good field distribution and propagation characteristics were obtained, and the antenna meets the safety standards.

This manuscript presents a UWB filter with three notch bands for WiMAX, WLAN, and X-Band Satellite Communication by introducing inverted E- and T-shape resonators shorted at the center, designed and fabricated for the use of UWB applications authorized by the US Federal Communications Commission. First, a UWB filter ranges from 2.8 GHz to 10.6 GHz is designed by employing four λ/4 wavelength short-circuited stubs and then couples E- and T-shape resonators on either side of the main transmission line of the proposed UWB filter to achieve notch bands response centered at the resonance frequency of 3.3 GHz for WiMAX applications, 5.1 GHz for WLAN wireless applications, and 8.3 GHz for X-band satellite communication systems, respectively. The proposed filter is able to produce three individually control stopband frequencies centered at 3.3 GHz, 5.1 GHz, and 8.3 GHz with minimum attenuation levels of -28 dB, -19 dB, and -15 dB, respectively. This indicates that the presented filter can efficiently reject superfluous bands at 3.3 GHz in WiMAX system, 5.1 GHz in WLAN system, and 8.3 GHz in satellite communication systems to improve the performance of the UWB communication systems. Finally, the proposed filter with circuit area 34 mm × 12 mm × 0.762 mm between the simulated and fabricated measurements.

A novel and compact CPW fed triband antenna suitable to support WLAN and WiMAX communications in 2.4/3.5/5.5 GHz bands is reported. The 5.5 GHz band extends from 4.9 to 5.94 GHz. So the proposed antenna can support the use of 4.94-4.99 GHz band allotted for fixed and mobile service (except aeronautical mobile service) for use in support of public safety and 5.85-5.925 GHz band for Dedicated Short-Range Communications (DSRC) services in the Intelligent Transportation System (ITS) radio service. Metallic radiating stub extending from the feed is used to excite the resonance at 2.4 GHz. An open slot in the stub and a pair of open slots in ground plane are used to excite the other resonances. An arc shaped parasitic element is also included in the design for improved radiation performance. The proposed antenna geometry is developed on FR4 glass epoxy substrate with relative permittivity 3.8 and loss tangent 0.02. The geometry is developed and optimized using High Frequency Structure Simulator and experimentally validated the results. Performance comparison of the proposed antenna with similar antennas in literature is presented. Measured radiation patterns and gain are also included in this paper.

The problem of radiation of a magnetic dipole axially symmetric with an infinitesimally thin perfectly conducting circular disk is solved in an exact closed form. This is done by transforming the original dual integral equation system describing the problem into a single second-kind Fredholm integral equation and searching for the solution as a power series. Both low- and high-frequency asymptotic limits are also discussed from which simple approximate solutions are readily derived. Numerical results are provided to validate the proposed formulation.

A differentially compact dual circularly polarized (CP) concentric ring traveling wave-fed quasi-lumped resonator (QLR) array working at 5.8 GHz is presented. The array consists of seven series QLRs, each with an interdigital finger capacitor, connected by a parallel narrow-strip inductor. The CP was obtained by organizing the radiating QLR over a concentric ring-fed microstrip. The QLR was fed with a current of the same magnitude and some phase delay at each element. The dual-port feeding permitted the selection of the traveling wave direction and, consequently, the mode of CP. The measured bandwidth was 5.76-5.8 GHz at port 1. Meanwhile, the bandwidth was 5.75-5.77 GHz at port 2. The measured peak gain was 5.9 dBi at port 1 and 6.4 dBi at port 2. The cross-polarization was 19 dB lower than the co-polarization at port 1, which is a characteristic of right-hand circular polarization (RHCP). The cross-polarization was 14 dB higher than the co-polarization at port 2, which is a characteristic of left-hand circular polarization (LHCP). The size of each radiating element was 5.8 × 5.6 mm², and the array was 40 × 40 mm². These features and its compact size make the proposed array antenna a good candidate to be used in wireless systems.

Due to certain conditions, electrical motor (EM) that operates at high speed may lead to magnetic saturation, thermal issue and stress to rotor structure. Magnetic gear (MG) designed for speed multiplier enables the prime mover from EM to operate at lower speed while the output gear multiplies the speed by its designated gear ratio at reduced torque. In this paper, a new coaxial magnetic gear is designed for speed multiplier. The role between inner yoke with PM and pole piece is switched. The inner part of magnetic gear is made to be stationary while the pole piece becomes inner rotor. The working principle is presented analytically. It used flux modulation techniques for torque and speed transmission. Torque characteristic and gear efficiency is analysed using finite element, and compared with existing speed multiplier magnetic gear with the same gear ratio of 7/3. Based on the simulation result, the proposed speed multiplier MG offers 16% better torque density and 12% higher gear efficiency at higher speed range. The structure of the inner rotor was also found to be more robust as only pole piece ring together with plastic is rotated instead of yoke with PM.

In this paper, a dual-band bandpass filter using sixteenth-mode substrate integrated circular cavity (SM-SICC) and a novel ultra-wideband (UWB) bandpass filter (BPF) using eighth-mode SICC (EM-SICC) cavity are presented. The TM101, TM102, and TM201 resonant modes of the substrate integrated waveguide (SIW) circular cavity are used to design the dual-band filter, where the resonant frequencies can be shifted to the desired frequency through adjusting the position and size of complementary split-ring resonator (CSRR). In addition, the TM101, TM102, TM103, and TM104 resonant modes are employed to realize the UWB filter. A transmission zero appears by introducing the complementary split-ring resonator (CSRR) in the middle of the SICC, so the dual-band BPF and UWB BPF with high selectivity are realized. The proposed filters possess compact size, because of the EMSIW and SMSIW cavity. The dual-band filter operating at 7.79 and 12.83 GHz is fabricated in SM-SICC with 3-dB fractional bandwidths (FBWs) of 7.8% and 31.25%, respectively. The UWB filter with FBW of 97% is simulated in EM-SICC. Compact circuit sizes and excellent measured performances have been achieved for the two filters.