In this paper, a novel heterogeneous swastika structured hexagonal photonic crystal ring resonator for the realization of universal logic gates is designed using two dimensional photonic crystals. The proposed structure has square lattice of 16 × 16 hexagon-shaped chalcogenide glass rods embedded in an air substrate with a refractive index of 3.1. The choice of chalcogenide in the realization of optical logic gates benefits from wide optical windows in the mid-infrared region. Through plane wave expansion method, the contrast ratio for the proposed structures, namely, NAND, NOR, EX-OR, and EX-NOR gates is 22.6 dB, 17.20 dB, 18.3 dB, and 12.78 dB, respectively. Moreover, the footprint of the proposed structure is 9.24 µm × 9.24 µm.

This paper proposes a truncated arc patch antenna loaded with a novel complementary slotted split ring resonator (CSlSRR) in the ground plane. The antenna achieves wide bandwidth, circular polarisation (CP), and omnidirectional radiation pattern in the S-band. The electrical size of the antenna is 0.36λ₀ × 0.31λ₀, and the radiating metal dimension is 0.18λ₀ × 0.21λ₀ (λ₀ corresponds to f₀ = 2.45 GHz). Truncated corners with a semi-circular arc produce CP with the inset feed. The CSlSRR helps in improving the bandwidth and miniaturisation of the antenna. The design achieves a size reduction of 61%. The fabricated antenna exhibits 12.3% impedance bandwidth (IBW), 4.07% axial ratio bandwidth (ARBW), and a maximum gain of 2.476 dBi at 2.75 GHz. The antenna prototype is characterised in an anechoic chamber. The paper carries out a comparison of the measured and simulated results and other reported works in literature.

Coupling coefficient of a magnetic coupler is a key factor that affects the efficiency of wireless charging system. DD-type couplers have the most common topology in the literature. However, they have low coupling coefficients. In order to obtain high coupling coefficient of magnetic coupler, firstly, the magnetic circuit models of DD-type and solenoid-type magnetic couplers commonly adopted in electric vehicles are built in this paper. Secondly, a hybrid DD-solenoid type coil winding is proposed based on the analytical model, and the optimized design of the magnetic core and shielding structure are also introduced in this paper. Thirdly, an optimization design method for magnetic coupler is proposed. 3-D finite-element analysis (FEA) and experimental results verify the theoretical analysis. It is shown that the performance of the hybrid winding method proposed in this paper is significantly improved compared to the traditional DD winding method, and it can also keep the high offset tolerance characteristics of DD winding. In the meantime, the proposed method can increase the coupling coefficient and decrease the cost through optimization of magnetic core, and the shielding structure can effectively reduce the electromagnetic interference.

The novel design of an ultra-wideband calorimeter for energy measurement of high power microwave pulses of nanosecond duration is proposed in this paper. The main idea is the use of a circular waveguide with losses in the wall and metal cone insertion at the axis to increase attenuation constant in the waveguide. The efficiency of the concept was proved with the numeric simulation and optimization of the calorimeter design with ANSYS HFSS software for frequencies from 8 to 38 GHz. The operating modes are supposed to be symmetric TM_0n ones. Ethanol was chosen as an absorbing medium. It is parted from the vacuum volume by a plastic tube. The frequency dependencies of ethanol's relative permittivity and loss tangent were taken into account in the simulation model. The reflection coefficient for TM₀₁ mode is below -20 dB at the lowest frequency of 8 GHz and well below the level of -25 dB from 10 to 38 GHz. The reflection coefficients for higher order modes remain below -30 dB until the operating frequency is close to the cut-off frequency for a particular mode. The maximum accepted power level is of hundreds of megawatts for pulses of a nanoseconds duration. The effect of waveguide modes mixture at the input of the calorimeter on the maximum accepted power level was considered. This level may differ by 4 times between specific modes mixtures. Therefore, the transition from a particular microwave source to the calorimeter input should be carefully optimized.

Nowadays, the key to design a reliable communication system is to acquire channel characteristics and improve channel capacity. In the transmission of high-speed data, the unshielded transmission channel used in power line communication has interference factors such as noise, attenuation, reflection, radiation, and time-varying. A three-wire MIMO-PLC channel transfer function priori model has been established based on the theory of MTL in this paper, which is necessary for band pre-selection, power setting, and dynamic range design in a high-speed MIMO-PLC set to improve the unshielded transmission channel capacity with the effect of noise, attenuation, reaction, radiation, and time-varying factors. The simulation results with the model parameters of geometric sizes, material, surrounding medium, and lengths of the power line network agree well with the measurement ones in the frequency band of 1-200 MHz. The research results of this paper have guiding significance for the band pre-selection, power setting, and dynamic range design of broadband MIMO-PLC.

Human intention recognition is important for any interaction between the user and the exoskeleton. This study proposes a novel approach, based on a contactless sensory system, using linear Hall effect sensors to recognize human intentions. This contactless sensory system consists of four Hall effect sensors mounted on the exoskeleton, whilst a ring-shaped permanent magnet with diametrical magnetization consisting of two semi-rings is worn on the user's forearm. The model of the magnetic field created by the permanent magnet is also developed. Based on the developed magnetic field model and by interpreting the signals from the Hall effect sensory system received while the user's elbow and forearm move, the intention identification algorithm is derived. A lightweight elbow and forearm assistive exoskeleton is developed. The proposed approach for human intention recognition is used to assist in controlling the exoskeleton, following the wearer's intended motions. By implementing this contactless sensory system, wearers can use the exoskeleton easily and can move their forearm comfortably, while the human intention motion is recognized and used to control the exoskeleton. Moreover, achieved signals are unaffected by skin perspiration and muscle fatigue. As the sensory system is mounted on the exoskeleton, there is only indirect contact between the user's body and the sensors, leading to improved comfort. Finally, the system does not require expert knowledge to place the sensors on the body of the user. This approach can be extended to detect human intentions for the control of exoskeletons with more degrees of freedom.

Microwave imaging (MWI) is a non-ionizing, non-invasive and an upcoming affordable medical imaging modality. Over the last few decades, MWI has invited active research towards bio-medical imaging, with special focus on breast tumor detection. After long years of intense research and clinical trials, a breast tumour monitoring unit based on MWI is finally entering clinical imaging scenarios. In this manuscript, the vast literature in MWI to date has been consolidated, and an in-detail study of the state-of-the-art for breast tumor detection has been presented. The hurdles faced during clinical trials are discussed, and their possible solutions and future directions for a fast transition into clinical imaging have been presented. It is hoped that this paper can serve as a guide for MWI researchers and practitioners, especially those new to the field to comprehend the potential of MWI as a viable imaging tool for breast imaging.

This paper presents a compact single feed circularly polarized (CP) antenna along with a frequency selective surface (FSS) that acts as a partially reflective surface over the patch. Patch is loaded with four diagonally asymmetric complementary split ring resonators (CSRRs) in order to achieve circular polarization. In this paper a novel design of reflective type FSS layer is presented at 2.4 GHz. The size of FSS unit cell is approximately 0.132λ₀ × 0.132λ₀, and it is placed at a distance of 0.146λ₀ from the patch. Simulated impedance bandwidth of the antenna for S₁₁ < -10 dB is from 2.385 GHz to 2.506 GHz (121 MHz or 4.95%) which covers the entire IEEE 802.11 WLAN band (2.4 GHz-2.484 GHz). Position of the four CSRRs on the patch and the height of FSS screen are determined through parametric studies, and the detailed analyses in terms of reflection coefficient, axial ratio, and gain variation are also presented. Gain of the antenna is 3.02 dBic at the operating frequency 2.45 GHz. Measured results are in good agreement with the simulated ones.

In this article, the Modal Expansion Theory (MET) is applied to 3-D metamaterial waveguides. The equivalent surface impedances of the metamaterial are computed thanks to an open software: GetDP, based on a 3-D Finite-Element-Method (FEM). This program is called during the MET algorithm, which allows considering the frequency and incidence angle dependency of the surface impedances of the metamaterial to compute the dispersion diagrams and the field cartography. To validate the dispersion diagrams obtained with this technique, another FEM commercial software (HFSS) is used as a reference.

In order to improve the efficiency of transformer fault diagnosis and monitoring in power systems, and to realize fault diagnosis of unmanned remote adaptive transformer equipment, we present a method of multi-sensor and multi-direction optical image integrated monitoring in this paper. By monitoring and collecting transformer fault information combined with the changing characteristics of transformer temperature and electrical signals, we establish a transformer calculation model based on multi-level fault and multi-characteristic parameters. According to the characteristics of transformer faults, we use a deep belief network identification (DBNI) algorithm for the transformer and construct the training samples of the transformer diagnosis model using an optimum weight fusion algorithm. The experimental results show that the DBNI model can fully explore the characteristics of large samples, analyze multiple faults information, and extract the hidden features of fault samples. The DBNI model has higher fault diagnosis accuracy than a BP neural network and a single DBN without data fusion and SVM. The DBNI's fault diagnosis accuracy reaching 99.45%. The experimental results show that this model has good robustness of interference ability and can be used intuitively to carry out remote on-line unattended transformer fault diagnosis and information feedback.

This article investigates the optimal design of a magnetic-planetary-gear permanent magnet (MPG-PM) machine. The key is to develop a design method for the pole shoe thickness, stator outer diameter and coil turns of the MPG-PM machine in such a way that the torque waveform is sinusoidal. The magnetic field distributions is solved by the finite element analysis according to the optimization results. A prototype of MPG-PM machine is used for exemplification in terms of the experiment performance requirement. Both the predicted and measured results are given to illustrate the proposed machine. The theory analysis and the experimental results show that the magnetic circuit of the MPG-PM machine is correct, and the torque satisfies design requirements. It provides reference and application value for developing high performance and low-cost MPG-PM machine.

Concentric circular slots coupled hemispherical dielectric resonator antenna fed by a modified microstrip line for circular polarization is investigated. By adjusting the position of the hemispherical dielectric resonator antenna and the slot properly, the resonance of the slot and the antenna is merged to obtain wider axial ratio bandwidth. Parametric studies have been done on the effect of changing the DRA position on impedance band and axial ratio band. The circular polarization achieved by the antenna offers a very good 10 dB impedance bandwidth of 27.379% and a 3 dB axial ratio bandwidth of 640 MHz. The maximum gain in the operational band is 7.3 dBi. The antenna is suitable for Wi-Max applications.

Slotless double-sided outer armature permanent-magnet (PM) linear motors (SDOPMLs) have high efficiency and low detent force. Despite their simple control strategy and easy manufacturing process, finding an accurate model of these motors to calculate the machine quantities is challenging. It is particularly critical for obtaining the optimum design of these machines which may include too many iterations in a short time. To overcome this challenge, a 2-D analytical model based on the sub-domain method is presented to determine the magnetic flux density components for the motor under the study. According to this analytical procedure, the motor cross-section is divided to 11 sub-regions, then the superposition theorem is utilized to analyze the flux density distribution in all sub-regions due to various magnetization patterns, (i.e.， parallel, two-segment Halbach, ideal Halbach, and bar magnet in shifting directions) as well as armature reaction current, respectively. According to the calculated magnetic flux density components, machine quantities like flux linkage, induced voltage, inductances and electromagnetic force components are explained. Also, the obtained analytical results are compared with those of the finite-element method (FEM) to confirm the accuracy of the proposed model. The proposed model can be used in the design and optimization stage of the linear slotless motor against the numerical model to save time. Finally, a comparative study between the performance of the single-sided and double-sided slotless PM linear motors in the same volume is implemented. This comparison shows the advantage of the double-sided motorin terms of the unbalanced magnetic force (UMF).

This paper analyzes the high-frequency energy distribution of a paraboloid reflector in the presence of a uniform plasma layer. The curved surface of the paraboloid reflector is thought to be coated with a uniform plasma layer. The geometrical optics technique shows a singularity at the focal point of the paraboloid reflector. The singularity is removed with the help of Maslov's method, which also let us derive the integral equations that give the high-frequency energy distribution at the focal point. The analytical integral is solved numerically using a computational technique, and the effects of plasma frequency, collisional frequency, operating frequency, and multiple reflections on energy distribution at the focal point are observed. Under the special conditions our analytical and numerical results are obtained which align with the published literature.

A novel design of an enhanced Yagi-Uda antenna is introduced for dual-band operation at 28/38 GHz. The antenna is constructed by a corrugated dipole strip and a capacitively end-coupled extension strip as the driving element, two reflectors, and one director. Periodic parasitic elements are added in front of the reflectors to enhance the antenna gain and improve the impedance matching. The driving dipole is fed through a coplanar strip line, and in order to facilitate the experimental measurements using a coaxial feed line, a microstrip to coplanar strip (CPS) line transition is employed. A four-port MIMO antenna system is constructed using the proposed Yagi-Uda antenna arranged at the edges of the mobile handset. Numerical and experimental investigations are achieved to assess the performance of both the single-element antenna and the four-port MIMO antenna system. It is shown that the simulation results agree with the experimental measurements, and both show good performance of the single antenna as well as the MIMO antenna system. The bandwidths achieved around 28 GHz and 38 GHz are about 3.42 GHz and 1.45 GHz, respectively, using the microstrip feed line. Each antenna has a maximum gain of about 9 dB. The four antenna configuration shows radiation pattern diversity required for MIMO system. The envelope correlation coefficient (ECC) and diversity gain (DG) are calculated, and the results show that the proposed MIMO antenna system is suitable for the forthcoming 5G mobile communications.

Reconfigrable antennas that are able to provide a high spatial diversity are increasingly adopted in many wireless applications. An original design of a planar printed compact antenna that achieves an electronically controlled beam steering by using metamaterial hybridization is presented in this paper. The designed antenna, made of coupled split ring resonators, is able to switch between 8 radiation patterns steering in 8 different directions at the working frequency of 2.45 GHz. The spatial diversity is assessed from the analysis of the correlation matrix between the patterns. This concept would provide a promising and compact alternative for low power telecommunication systems.

In this paper, an ultrawide band (UWB) notch antenna with electromagnetic bandgap (EBG) structure for WiMAX and satellite applications is proposed. The proposed design contains an inverted-π model slot and EBG element which create lower and upper notch frequency bands respectively. The designed antenna is fabricated on a Rogers RT/duroid 5880 with the dimensions of 18 mm × 21 mm × 1.6 mm³ which is fed with a 50 Ω transmission line. The proposed antenna has a range frequency from 2 GHz to 12 GHz, in which lower notch covers 3.3-3.7 GHz (WiMAX), and upper notch covers 5.9-6.9 GHz (satellite uplink application). The proposed antenna measured and simulated results are in good correlation. It has good radiation characteristics in the required frequency bands.

A general resonant condition for rectangular waveguide junctions operating in the single mode regime of the main waveguide is formulated based on previously developed mathematical models. We will consider three types of junctions with various side arms: T-oriented semi-infinite waveguide with an impedance end wall, semi-infinite waveguide oriented in line with main waveguide, and infinite perpendicularly oriented waveguide. The main waveguide is coupling with the side arm through a narrow slot, and it has a dielectric inclusion in the coupling region. As a result of the analysis of the resonance characteristics for the indicated types of waveguide devices, the correctness of the application of the general resonance condition is substantiated. The possibility of neglecting the imaginary part of the permittivity of the inclusion material in calculations is confirmed by a satisfactory agreement between the numerical results and experimental data for an isolated inclusion.

This paper presents a hierarchical saliency detector for ship detection in synthetic aperture radar (SAR) imagery. First, the nonlinear anisotropic diffusive process has been adopted to eliminate clutter, while preserving the target edge feature in SAR image. Second, each pixel in the filtered image is assigned to its corresponding super-pixel region via an adaptation of optimization technique. Third, Gamma manifold for feature representation has been presented for the modeling of intensity of all super-pixels in SAR imagery. Fourth, a threshold segmentation method is used to realize ship detection. The proposed method is an automatic detection process without any sliding window. Experimental results accomplished over real SAR images demonstrate that the proposed detection method can achieve a good performance.

This letter proposes a novel single-layer fourth-order balanced bandpass filter based on two coupled dual-mode loop resonators. Two pairs of balanced input/output (IO) feeding lines with unequal arms are employed to excite the outside dual-mode loop resonator, and the inside dual-mode loop resonator with meander lines is coupled to the outside one. Under differential-mode (DM) operation, three finite transmission zeros (FTZs) can be produced and controlled. Under common mode (CM) operation, the rejection level can be controlled by the length of IO feeding arms. For the demonstration, a balanced dual-mode loop filter with the center frequency of 5.2 GHz is designed, fabricated, and measured. The proposed balanced filter has the advantages of compact size, high selectivity, wide stopband of DM response, and good CM suppression.