A novel variable flux permanent magnet vernier machine (VFPMVM) is proposed by introducing the concept of hybrid excitation, and its flux modulation poles (FMPs) and excitation winding are emplaced in stator teeth and the adjacent FMPs, respectively. It can offer several merits, such as wide speed range operation through the processing of flux-enhancing and flux-weakening without increasing machine bulk, as well as the numbers of stator slot and rotor pole. Moreover, as one sort of flux modulation machine based on magnetic field modulation effect, VFPMVM features low speed, large torque, simpler mechanical structure and better utilization of PM materials than traditional flux modulation machines. The working principle of proposed machine is studied, and basic electromagnetic characteristics are calculated by finite element method, including no-load magnetic flux linkage, no-load back electromotive force, cogging torque, and output torque. In addition, the processes of flux-enhancing and flux-weakening are analyzed. Finally, one prototype with one kilowatt was built, and its static characteristics were tested. The results show that the proposed VFPMVM has the merits of high torque density, small cogging torque, and wide speed range, which is a promising candidate for electric vehicle direct drive field.

In wireless technology, microstrip patch antennas are often used in communication systems with various designs. However, the effect of geometrically folded antennas on wireless communication performance is unclear. To address this problem, an in-depth study of the flexible antenna parameters was performed through V-folding analysis. A systematic and complete analysis of the percentage of folding in patch antennas was performed. The folding of patch antennas is expected to become mandatory because patch antennas are integrated and molded according to specified object shapes. The designed antenna was operated at 0.1-5.0 GHz to investigate the folding performance in the frequency range of 1.00-3.78 GHz used in many wireless applications, such as the GPS, GSM, and LTE standards. A promising operating frequency for flat (unfold) antennas is 1.42 GHz with an achieved multiband bandwidth of 31.6 MHz, which shifted according to the folding angle but with good performance. The results of this study can be used to predict the performance of an antenna when it is placed on a product of any shape, according to the designed object pattern.

In underwater wireless sensor networks (UWSNs), the limited availability and non-rechargeability of sensor node batteries necessitated the advancement of energy optimization techniques. Optimal clustering is one such technique that reduces the energy consumption of the networks. In this letter, we propose optimal cluster compression technique jointly with energy harvesting. In optimal clustering compression, we perform optimal clustering of networks with singular value decomposition (SVD) as compression technique to reduce the redundant data generated at the cluster heads (CHs). Besides, adopting energy harvesting technique, node batteries are periodically recharged. The performance of the proposed model is evaluated in terms of network lifetime and throughput.

A compact novel lamp slotted upper WLAN band rejected ultrawideband (UWB) radiator integrated with Ku and partial K bands is reported. The intended radiator consists of a novel lamp slotted patch structure with a 50 Ω tapered microstrip feed line along with a novel semicircular defected ground structure (SCS-DGS). The size of the suggested radiator is 16×22 mm² with an impedance bandwidth ranging from 3.63 to 21.94 GHz to cover UWB integrated with Ku and partial K bands, and a novel via notched element is utilized to notch the upper WLAN band from 5.31 to 6.05 GHz. The proposed antenna has stable radiation patterns, consistent gain, and a peak radiation efficiency of 92.15% except for the notched band which mak it suitable for upper WLAN band notched UWB wireless communication applications.

This paper presents the mathematical formulation for the generalized closed-form expressions to calculate sideband power (P_SR) of a nonuniform period time modulated array (NTMA) antenna with volumetric geometry by using pulse shifting strategy. For the arbitrary array geometry, the generalized expression of P_SR is obtained by considering the universal omnidirectional element pattern in the form sin^aθ|cosθ|^b, a > -1, b > -1/2. Then, corresponding to different array structures such as linear, planar, and volumetric ones, the derived expression is simplified for different element patterns with possible combination of `a' and `b'. Through representative numerical results it is demonstrated that the obtained simplified expressions without hypergeometric function are useful to accurately calculate the amount of power losses due to sideband radiations with significantly less time than the conventional numerical integration (NI) method.

A new defected ground structure (DGS) with two transmission zeros is presented for the first time by loading the conventional dumb-bell-shaped (DBS) DGS with the comb-shaped structure. Equivalent circuits are developed and electric parameter extraction is derived. The low-pass filter (LPF) design method based on the proposed new DGS is given. The fabricated filter demonstrates a sharp, wide and high stopband rejection with an ultra-wide 20 dB rejection bandwidth of 21.9f_c and the sharp attenuation rate is more than 129.4 dB/GHz.

This article presents a broadband circularly polarized (CP) semi-annular ring-shaped printed monopole antenna for wireless applications. A semi-annular monopole with symmetric partial ground plane is designed to achieve the impedance bandwidth with a behaviour of linearly polarized (LP) radiation wave. To achieve the CP behaviour with broadband axial ratio (AR) bandwidth, an asymmetric stair shaped partial ground plane is incorporated in the semi-annular ring-shaped monopole structure. Different analysis of CP radiation is presented by analysing the surface current distribution, electric field distribution and also its mathematical modelling using CST-MWS solver. Moreover, an equivalent circuit model of the proposed monopole antenna is developed using Foster canonical forms. The measured -10 dB impedance bandwidth and 3-dB AR bandwidth are 8.78 GHz [3.22-12.0 GHz] and 2.21 GHz [7.58-9.79 GHz] respectively. The peak realized gain and antenna efficiency are 4.32 dB at 7.61 GHz and 82% at 4.83 GHz respectively. The proposed antenna can be suitable for C-band (4-8 GHz) and X-band (8-12 GHz) applications.

An Ultra-wideband Microstrip fed patch antenna with a defective ground surface is presented in this paper. The above-mentioned antenna comprises a T-slot in the ground plane and a Pi-slot in a rectangular patch. The proposed antenna is developed and modeled using the High-Frequency Structure Simulation tool on an RTDuroid 5880 substrate with a thickness of 1.6 mm and a dielectric constant of 2.2. A T-shaped defect is carved in the ground plane to enhance the antenna's radiation properties, gain, and bandwidth. A conventional Pi-slotted patch antenna operating at 9.74 GHz with a return loss of 19.7 dB is designed, followed by an ultra-wideband antenna embedded with a T-slot in the partial ground surface operating from 7.15 GHz to 10.925 GHz with an impedance bandwidth (S₁₁ < −10 dB) of 3.775 GHz. It showcases exceptional characteristics with a peak gain of 6.99 dBi at 8.95 GHz. A satisfactory agreement is found between the experimental data and simulation results. The proposed Pi-slot patch antenna with the defective ground has applications in radar, satellite, weather monitoring, and vehicle speed detection for law enforcement.

This paper proposes an improved design of a W-band slot array antenna, based on a ridge waveguide and a rectangular micro-coaxial line. To achieve a high gain and wideband antenna with element spacing smaller than half a wavelength, a broadband transition of rectangular coaxial line to ridge waveguide was designed. The improved design has bandwidth around 15.4 GHz (94.8 GHz-110.2 GHz), and the simulated realized gain is about 14.6 dB. Measured results of the fabricated antenna demonstrate that the gain at theta = 0°, and VSWR is better than 13 dB and 2.7, respectively. The antenna's size is about 12 mm × 5.5 mm × 0.46 mm.

A new technique to reduce the mutual coupling between closely-spaced, single-layered patch antenna elements is presented. The proposed design comprises an integrated novel decoupling structure to generate an out-of-phase decoupling signal to effectively lower the coupling between the elements. In addition, coplanar L-probes and interdigital filter shaped slits on the ground plane are incorporated to further improve the isolation. The realized isolation level is about 28 dB at the frequency of operation. This is a significant achievement for a single-layered low-profile structure, wherein the center-to-center element spacing is only around 0.25λ₀, and more importantly, no shorting vias are used.

A design technique to develop the desired pattern with uniform spacing between elements for a resonant linear slot array on the broad wall of a rectangular waveguide is discussed in this study. First, linear array pattern synthesis is used to achieve the amplitude and phase of the array element. Then both radiation pattern synthesis and the array input impedance matching are achieved using the least-squares method. In addition, the error function is created by combining the three terms of impedance matching, array pattern synthesis, and slot design equations. Genetic algorithm (GA) and the conjugate gradient (CG) technique are used to minimize the acquired error function. The utilized approach results in precise pattern synthesis, good impedance matching, development of appropriate design equations, and power loss minimization. The computing needs were also reduced using the suggested antenna design. The approach is particularly beneficial since it integrates slot parameter dimensions and impedance matching with array pattern synthesis, resulting in a faster and more accurate design. Full-wave simulation Software HFSS was utilized to validate the suggested design method. Moreover, the measurements were conducted on a prototype designed to validate the simulation's accuracy and the designed antenna practicality, and excellent agreements between theoretical predictions and simulation results were achieved.

The narrow beam-width 120 GHz industry, scientific, and medical band compact substrate integrated waveguide (SIW) driven antenna's design and characterization are discussed in this study. A low-cost fabrication is ensured by the employment of a single RO4350B substrate layer with SIW feeding. A transition from SIW to a rectangular waveguide is made for measuring purposes. The radiation pattern has been measured. By determining the right feeding phases for the 20 elements, a Deep Neural Network (DNN) is used to softly compute the beam steering. The weighted hybrid Modified Gravitational Search Algorithm (MGSA) - Particle Swarm Optimization (PSO) approach and neural network with back-propagation technique are utilized to beam-steer by anticipating the appropriate feeding phases of the antenna array elements. To evaluate the effectiveness of the approaches, a number of sample instances are given that beam-steer the pattern in a variety of directions. In addition to allowing for the establishment of crucial analytical equations for the synthesis of antenna arrays, the neural network synthesis method also offers a great deal of flexibility between the system parameters in input and output, which makes the synthesis possible due to the explicit relationship given by them. The conventional technique of the phased array is compared with our DNN model for implementing beam steering.

A circularly polarized dual band wearable antenna using frequency selective surface backed reflector for radio frequency identification reader resonating at global ultra-high frequency band (860-960 MHz) & ISM band (2.4 GHz) is proposed in this work. For circular polarization, the corner is truncated at the opposite end of a square patch with periodic slots over the patch for getting an orthogonal electric field in both the X & Y axis direction. Another truncated inner square slot patch miniaturizes the antenna further for stable frequency response. Finally, the periodic frequency selective surface-based reflector is used for gain enhancement & crosstalk reduction. The simulated & measured results for antenna over human body are plotted against the required bandwidth. The return loss and maximum radiated gains of -31 dB and 8.30 dB are achieved at a resonating frequency of 2.4 GHz with the reading range and Specific Absorption Rate (SAR) of 6.98 m and 0.77 watt/kg respectively. At 865 MHz the return loss & maximum radiated gain is -23 dB & 5.31 dB with the reading range & SAR of 5.21 m & 0.65 watt/kg respectively. The proposed UHF RFID antenna is circularly polarized with the axial ratio bandwidth less than 3 dB with approximately 15% (860-965 MHz & 2.4-2.45 GHz) range. The designed wearable antenna provides better isolation when FSS is incorporated while enhancing the gain for longer read range. The FSS reflector below the antenna reduces the SAR for on-body wearable applications. This RFID antenna can be used efficiently for WBAN applications as a portable RFID reader wearable antenna for remote sensing & real time monitoring.

Interrupted Sampling Repeater Jamming (ISRJ) is an electronic countermeasure against radar echo signals that generates many false targets to mask the real target echoes, which seriously affects radar target detection performance. Most of the ISRJ suppression methods require accurate estimation of the signal parameters, and the estimation methods are complex. Based on the characteristics of discontinuous ISRJ sampling and orthogonality between multi-carrier phase coding (MCPC) signal's subcarriers, we propose a method for ISRJ identification and suppression based on an improved MCPC signal. By analyzing the pulse compression of the echo, we found that different types of intermittent sampling interference have different peaks after pulse compression. Based on this feature, we introduce Fractional Fourier Transform to filter out interference. Theoretical analysis and simulation results show that the method can effectively suppress the three classical ISRJ interferences. The method suppresses ISRJ during echo processing without any parameter estimation for real scenes and has stronger robustness than other existing schemes.

A compact metamaterial-loaded wideband monopole antenna is reported in this paper for wireless applications. Initially, a monopole antenna with a single stub was designed to resonate at 4 GHz. Still, it suffers from low gain, so to enhance the antenna parameters, a metamaterial unit cell was considered along the feed line and ground plane. Double split ring resonator (DSRR) is a modified unit cell of a typical split ring resonator (SRR) designed to achieve a good coupling effect. The dimensions of the proposed DSRR unit cell are 0.17λ₀ × 0.17λ₀, where λ₀ is the free space wavelength at 4 GHz. It achieved an impedance bandwidth (-10 dB) in the frequency range of 3.38 GHz to 4.08 GHz & 4.64 GHz to 5.2 GHz, having a 19.49% bandwidth in the 1st band and 11.7% bandwidth in the 2nd band. A wideband was achieved in the frequency range of 3.39 GHz to 5.13 GHz with 47.9% bandwidth when the number of stubs was increased to four. A maximum gain of 3.3 dBi was attained with bidirectional radiation in the E-plane, and it was omnidirectional in the H-plane. By increasing the number of stubs, two resonant modes were merged, making it wideband and suitable for WLAN applications like Wi-Fi & WiMAX & Satellite Communications.

In this manuscript, quad port highly isolated sextuple-band notched ultra-wideband (UWB) multiple input multiple output (MIMO) antenna is designed and experimentally investigated. The suggested design employs four antenna elements fabricated over a Rogers RT Duroid 5880 substrate and placed orthogonal to each other by deploying polarization diversity technique for good isolation. By combining polarization diversity technique with a fan shaped de-coupler isolation could be improved even more. Ameliorated frequency selectivity of notch bands can be accomplished by loading each antenna element with four U-shaped slots and C-shaped stubs adjacent to the feed line to exhibit band rejection of 3.18-3.51 GHz (9.86%), 3.71-3.99 GHz (7.27%), 4.59-4.76 GHz (3.63%), 5.18-5.34 GHz (3.04%), 7.47-7.74 GHz (3.55%), and 9.29-9.55 GHz (2.76%) to surmount the possible intrusion from WiMAX, C-band, INSAT, WLAN, X-band, and radio navigation (RN) band. Besides, an RLC equivalent circuit has been examined by correlating with the outcome of the reported notch band UWB-MIMO antenna that evinces highly selective notch bands. The suggested antenna works in the frequency range of 2.1-11.2 GHz which is suitable for UWB applications. Simulation and experimental validation is done to analyze the response of the suggested antenna with respect to notch frequencies, current distributions, peak gain, radiation patterns, envelope correlation coefficient, diversity gain, mean effective gain, total active reflection coefficient, channel capacity loss, and multiplexing efficiency.

In this article, two antennas having partial ground plane, slot loading with microstrip line feeding are proposed for wireless and biomedical applications. Antennas resonate at 2.4 GHz with two different bandwidths. The first antenna having 20% bandwidth, i.e., the Ultra Wide Band (UWB) of 2.10 GHz-2.61 GHz that can be utilized for wireless application and the Federal Communication Commission (FCC) allotted band of 2.36 to 2.39 GHz for medical applications falls in this range. The UWB antenna has undergone additional tuning to make it appropriate for biomedical application. Additionally a parametric analysis of antenna's slot length, width and dielectric constant is performed to optimize the performance characteristics. The antenna is fabricated and tested using Vector Network Analyzer. The acquired results from simulation and measurement are in close match.

In this paper, an unequal Filtering Power Divider (FPD) adopting a novel dual-band resonator and inter-digital feeding lines structure is presented. By integrating the resonator and modifying coupling mode, filtering and unequal power distribution are all achieved on the base of the deformed Wilkinson power divider. Two sets of cascading resonators operating at 2.45/4.44G with the same structure are proposed for WIFI and other application. Keeping with the unchanged coupling mode, the unequal ratio of 2:1 is arrived by adjusting the strength of coupling. The two resonant frequencies can be adjusted independently to ensure the flexibility of the design. For verifying the theoretical designs and simulated results, a fabricated FPD is exhibited, analyzed and measured. The simulated results are in good agreement with the measured ones with slight variations.

This paper presents the general numerical dispersion relationship for the three-dimensional (3-D) Radial Point Interpolation (RPIM) method in lossy media. A similar analysis has also been carried out and compared with the traditional Finite-Difference Time-Domain (FDTD) method. Both methods investigate dispersion, numerical loss, and anisotropy versus electric conductivity. The RPIM reveals lower numerical loss errors (NLE) in a wide conductivity range at the considered frequency. Furthermore, the numerical experiments show that a slight increase in the conductivity, for the lossless case, has almost removed the numerical anisotropy dispersion, which improves the numerical resonance frequency precision. Therefore, this effect can be used as an anisotropy optimization technique for lossless media. Based on a close examination of the experimental results around the resonant frequency, the numerical error for the lossless case was divided by ten. As a result, the experimental and theoretical resonance frequencies are found to be in good agreement.

Microwave staring correlated imaging (MSCI) is a super-resolution imaging technique based on temporal-spatial stochastic radiation fields (TSSRFs), which requires an accurate calculation of the electromagnetic field at the imaging plane. However, systematic errors always exist in practice, such as the time synchronization and frequency synchronization errors of radar systems, which make it difficult to calculate the required TSSRFs accurately, and this deteriorates the imaging results. Meanwhile, some imaging algorithms have problems such as high computational complexity. In this paper, an intelligent MSCI method based on the deep neural network (DNN) is proposed, which can accomplish imaging directly from the echoes, avoiding the computation of TSSRFs. A multi-level residual convolutional neural network (MRCNN) is developed for the DNN, and simulations and experiments are carried out to obtain the dataset for training and testing the MRCNN. Compared with the conventional MSCI methods, the imaging results verify the effectiveness of intelligent MSCI in terms of imaging quality and computational efficiency.