To address the problems of torque ripple, vibration, and noise generated by cogging torque in a dual-stator single-rotor axial magnetic field permanent magnet motor, this article adopts an unequal thickness pole structure to reduce cogging torque. At first, the process of cogging torque generation is analyzed, followed by an examination of the mathematical formulation of cogging torque using the energy technique and the Fourier decomposition method. Then, the impacts of several pole optimization approaches on cogging torque reduction are then compared, and the findings are investigated using the finite element method to demonstrate the efficiency of the optimization method. The results show that the optimization effect of unequal thickness pole structure is the best. Lastly, the optimized motor's air-gap flux density, counter-electromotive force, harmonic content, and rotor mechanical strength were compared and studied to demonstrate that the unequal-thickness structure used in this research can increase motor performance. Finally, based on the determined motor parameters, experimental study of the prototype was carried out to verify the correctness of the motor structure and analysis.

Model predictive current control (MPCC) suffers from high computational effort, and control performance is affected by parameter mismatch. In this paper, a robust MPCC strategy with low complexity for permanent magnet synchronous motor (PMSM) is proposed, which reduces the computational complexity and improves robustness. First, a low-pass filter is used to obtain the current actual voltage, and the next-cycle voltage vector is obtained by angle compensation. And alternative voltage vectors (AVVs) are selected according to the location of the next-cycle voltage vector to reduce the control system computation. This part does not use motor parameters to avoid the influence of parameter changes. Then, the relationship between the current error and the input voltage and current sampling value is analysed. A low-complexity current prediction error compensation algorithm is designed to compensate the error caused by the mismatch of motor inductance and flux linkage, which enhances the robustness of the system. Finally, the experimental results demonstrate the correctness and effectiveness of the proposed strategy.

A Multi-Input Multi-Output (MIMO) dual-band antenna useful for advanced wireless services (AWSs) and wireless body area network (WBAN) applications is presented. To have dual bands of operation two techniques were used namely, Defective Ground Structure (DGS) and slotted patch. The lower operating band is spread over 108 MHz from 2.106 GHz to 2.214 GHz which covers AWS, UMTS, and LTE bands. The upper operating band is spread over 221 MHz from 4.141 GHz to 4.362 GHz which covers the WBAN band. The lower operating band is the result of perforation in the patch and inverted T-shaped ground, and the upper operating band is due to the two rectangular slots placed diagonal to each other in the patch and perforations in the ground. High isolation among MIMO elements is observed through a low Envelope Correlation Coefficient (ECC) of 0.0004. The design of a 2 × 2 MIMO antenna is realized using FR4 material with a size of 70 mm × 70 mm × 1.524 mm and Ansys HFSS tool. A high level of correlation between simulated and experimental results is observed which enables the presented MIMO antenna to be perfect for the proposed AWS and WBAN applications.

A super-wideband (SWB) antenna of enhanced performance is proposed to cover the frequency band from 3 to 30 GHz. The proposed antenna can be regarded as a two-arm antenna of fractal structure. Each of the antenna arms can be viewed as composed of multiple merged wideband fractal elements. Each fractal element is a wide-flare metallic sector-shaped radiator with circular (arc-shaped) edges to enhance the bandwidth over which the antenna impedance is matched to 50 Ω-feeder. A novel SWB balun is proposed for feeding the two-arm antenna of its balanced structure through the conventional coaxial feeder of its unbalanced structure. For experimental assessment of its performance, the proposed antenna is fabricated and measured by a vector network analyzer (VNA). The experimental results come in agreement with the results obtained by the CST® simulator. It is shown that the proposed antenna has a ratio bandwidth (RBW) of 10:1, percentage bandwidth (%BW) of 164%, and bandwidth-dimension ratio (BDR) of 1952. The efficiency of radiation of the proposed antenna is shown to begreater than 98% over most of the operational frequency band.

Advancement in radar component technology has led to a reduction in the size, weight, and power consumption of radar systems. Experimental radar systems can now be integrated onto smaller, maneuverable platforms, such as small unmanned aerial vehicles (sUAVs). Integration onto rotor-based sUAVs enables data collection over novel synthetic apertures which can be optimized for different scenarios. The design, simulation, and experimentation of a light-weight, ultra-wideband synthetic aperture radar (SAR) is presented here that will be used for the detection of obscured surface targets. The approach outlined herein uses 3-dimensional (3-D) imagery to vertically resolve clutter from the target. A vertical-grid aperture is presented which yields vertical resolution. Point spread functions are derived for both linear and vertical-grid apertures. The analytical expressions are verified using simulations. Finally, experimental data is used to form 3-D imagery and demonstrate the importance of vertical resolution in the discrimination between scatterers above the ground, as well as clutter mitigation.

A novel balanced-to-unbalanced (BTU) Bagley power divider (BPD) with input-reflectionless filtering characteristics is proposed. It features a balanced input port and three single-ended output ports, which is difficult to achieve by means of conventional BTU power dividers. The filtering characteristics are achieved by parallel coupled lines. To further improve the differential-mode filtering selectivity, stepped impedance resonators are applied to introduce two transmission zeros near the passband. The input-reflectionless characteristic in the bandstop region is achieved by loading absorptive branches. For verifying the proposed power divider topology, a prototype of microstrip BTU Bagley power divider operating at 1.0 GHz is designed and fabricated with 3-dB filtering bandwidth of 72%. Furthermore, 10-dB input-reflectionless bandwidth covers the full measurement frequency from 0 to 2.5 GHz. Good agreement between the simulation and measurement validated the proposed method.

In this paper, a wide harmonic suppression filtering antenna with high selectivity is designed. The filtering antenna adopts dual-layer structures. By introducing four parasitic patches around the top driven patch, the impedance bandwidth is widened. Moreover, the current directions on the driven patch and the parasitic patches are opposite in some frequency, so that the radiation null is introduced. In addition, a rectangular split ring DGS is etched in the middle of the ground plane, the lower sideband radiation null is introduced. Two sets of dumbbell-shaped defected ground structures are etched on the ground plane of the intermediate layer. The high-order harmonics are suppressed, and another radiation null is introduced. The experimental results show that the antenna operates at 2.46-2.66 GHz; the relative bandwidth is 7.8%; the peak gain is 3.8 dBi; and the S₁₁ is more than -3 dB at 3-13 GHz.

The paper represents a rigorous solution to the problem of diffraction of a normally incident plane electromagnetic wave by a circular hole in a perfectly conducting screen of arbitrary thickness, obtained using the eigenmode technique with allowance for the presence of a plane dielectric layer on a thick substrate behind the screen, which can play a part of a radiation detector. The main goal of the work is to describe the effect of diffractionlensless focusing in circular apertures and to determine the conditions of its appearance in the near zone of small holes, when its radius, the thickness of a screen and a dielectric layer are of the order of the wavelength.

In emergency departments and ICUs, a novel noncontact thermometer is urgently required to measure physical temperatures through common clothing to accomplish body temperature precise measurement for critical patients. Hence, a Ku band digital auto gain compensative microwave radiometer is proposed to get a higher theoretical temperature measurement sensitivity than a Dicke radiometer, benefit miniaturization design and reduce attenuation caused by common clothing. Meanwhile, a novel compensation method for receiver calibration is proposed to improve temperature sensitivity under non-ideal conditions, and the revised systematic calibration method is elaborated. Furthermore, in order to invert body physical temperatures through clothing, a microwave thermal radiation transmission model of clothed human body is constructed, and the microwave radiation apparent temperature equation of clothed human body is derived. Importantly, three groups of experiments are set up to confirm the designed radiometer's performance, especially the biological tissue temperature measurement. Results show that: 1) the designed radiometer has high temperature sensitivity and accuracy for unsheltered targets; 2) amplitude attenuation caused by cotton cloth for Ku band microwave is much smaller than that for infrared thermal radiation; 3) the designed radiometer can track physical temperatures of targets (such as water and swine skin tissue) sheltered or covered by cotton cloth relatively accurately. In conclusion, our designed Ku band microwave radiometer is certificated to have outstanding performance in temperature measurement for biological tissue through common clothing, which can be developed into a promising product in medical monitoring.

In this paper, an ultra-miniaturized, planar dual-band wearable antenna is proposed for bio-telemetry applications. The proposed antenna covers the 433 MHz and 915 MHz Industrial, Scientific, and Medical (ISM) bands with a compact volume of 0.000000384λ₀³. The antenna consists of a meander line on the top side of the substrate, while the backside is loaded with an inductive grid structure to achieve miniaturization. Moreover, the absence of vias in the design of the antenna offers a significant benefit in terms of simplifying the fabrication process. The design approach considers the integration of other components for device-level architecture. The antenna exhibits stable performance when placed on different human body parts, such as the head and hand. The evaluated specific absorption rate (SAR) complies with the regulated human safety standard. Additionally, the link margin (LM) calculation shows that the antenna could establish a biotelemetry communication link at a distance of 20 meters.

In order to remove the influence of the aperture fill time (AFT) for wideband array, the scaling principle of the Keystone (KT) transform is applied to eliminate the linear coupling between spatial domain and frequency domain of wideband array signal. However, the classic KT transform is implemented by interpolation Sinc which is difficult to apply in engineering and leads to the serious problem of insufficient data. To address this, a realization of the low-complexity KT transform is presented, and it is implemented using only the Chirp-z transform (CZT) and fast Fourier transforms (FFT). Additionally, an Autoregressive (AR) model is proposed to compensate the insufficient data for each range, and the order of AR is estimated by the rank of the signal covariance matrix. Simulation results demonstrate that the proposed algorithm significantly reduces computational burden and improves the performance of wideband array beamforming.

This paper presents a novel gap coupled suspended multiband microstrip antenna suitable for wireless applications like long term evolution (LTE), wireless local area network (WLAN), Amateur radio, and Sub 6 GHz 5G wireless applications. The proposed antenna is a single layer geometry suspended in air that employs a gap-coupled feed with a parasitic strip for tuning the input impedance. The overall dimensions of the antenna are 41.4 mm x 39 mm x 3.12 mm. The presented antenna offers a total of six resonant frequencies centered at 1.70 GHz, 2.77 GHz, 3.03 GHz, 4.26 GHz, 4.58 GHz, and 5.64 GHz. Measured resonant frequencies fairly match the simulated values. Further, the gain values at these frequencies are 7.29 dBi, 6.10 dBi, 7.39 dBi, 5.39 dBi, 6.22 dBi, & 7.03 dBi, and the corresponding measured gain values are 6.92 dBi, 7.72 dBi, 4.88 dBi, 5.34 dBi, 4.25 dBi, and 6.51 dBi, respectively. Radiation patterns were measured at all these frequencies and found to have highly stable radiation characteristics except for slight asymmetry at the high frequency end of the operational band.

Composite materials are being widely used in the automotive industry where they are progressively replacing metallic materials as structural parts for being robust and lightweight. Their complexity, often leading to lots of unknown behavioral effects when placed near the electronic systems present in vehicles, should be studied and treated. In the automotive industry, the shielding effectiveness of these materials should be considered as the most important parameter to be known in advance. Faurecia, one of the world's largest leading automotive suppliers, sought to assess the shielding effectiveness of their product such as dashboards and door trims. Their objective was to enhance the shielding effectiveness, thereby ensuring superior isolation and protection of electronic systems against electromagnetic interferences (EMI). Thus, this paper presents a novel method for characterizing the shielding effectiveness of various composites using two electromagnetic methods to cover a wide frequency range, starting from 10 Hz up to 8 GHz. The first method, based on loop antennas, was used to cover the low frequency range starting from 10 Hz up to 120 MHz. Frequencies between 100 KHz and 1.5 GHz were not discussed in this paper because of the many studies that already exist at this frequency range, using the coaxial transmission cell. The second method used for frequencies higher than 1.5 GHz, consists of ultra-wide band antennas (Vivaldi).

A new non-singular fast terminal Sensor-less sliding mode control algorithm (INFTSMC) for IPMSM based on an improved extended sliding mode disturbance observer (IESMDO) is constructed to address the problem of degraded control performance of IPMSM because of uncertainties. Firstly, a mathematical model of IPMSM under parametric ingestion is developed, and a new control law for the speed loop is designed. Then, an improved non-singular fast terminal sliding mode speed controller (INFTSMC) based on a novel extended sliding mode disturbance observer (IESMDO) is designed, where an improved super-twisting control law is designed to speed up convergence, while IESMDO can accurately observe the unknown perturbed part F of the system in real-time relative to the sliding mode disturbance observer (SMO). Finally, high-order square root cubature Kalman-filter (CKF) combined with an adaptive estimator is proposed to accurately estimate the speed and rotor position of the motor in real-time. Through simulations and semi-physical experiments with PI and traditional NFTSMC, it is verified that the algorithm has better transient steady-state performance when external disturbances and parameter perturbation are added externally to the motor, which is conducive to improve the control effect of IPMSM.

Today's 5G wireless communication evolution system demands millimeter wave frequency range antenna for its uses in several applications for future communication devices. A 2-port Asymmetric Flare-Shape Patch Multiple Input Multiple Output (MIMO) antenna for mm-wave communication system is designed and presented. The antenna structure is constructed on a Rogers RT Duroid 5880 dielectric substrate with 1.6 mm thickness, 2.2 dielectric constant, and 0.0009 loss tangent. The constructed MIMO structure has an overall size of 14×19.2 mm². The proposed MIMO design has -10 dB return loss performance over a frequency range of 20-40 GHz with more than 20 dB isolation between antenna elements, which shows the low mutual coupling between antenna elements. The performance of the suggested MIMO antenna is reported in terms of return loss, gain, ECC, surface current, and radiation pattern. The simulated and measured MIMO antenna performance characteristics are in good agreement. The suggested design achieves more than 20 dB isolation and 8.17 dB gain with an ECC value lower than 0.0002, which meets the diversity performance of the MIMO design with two antenna elements. The proposed MIMO design is compact and the best choice for 5G mm-wave applications.

Over the last three decades, the presence of electromagnetic radiation in the open environment has increased by many folds due to wide utilization of cellular data and voice communication over multiple wireless communication bands. Thus with the increased utilization of electromagnetic energy, several global as well as national electromagnetic exposure regulatory norms have been put in effect across geographical boundaries to safeguard humans from immediate effects of Radio Frequency radiation. Specific Absorption Rate (SAR) quantification is well established in literature to measure the rate of electromagnetic energy absorption by living objects (humans as well as plants) while external microwaves impinge on them. It should also be considered that plants do absorb fairly reasonable amount of electromagnetic energy mainly from cell tower and Wi-Fi antennas owing to high permittivity (ε'_r) and conductivity (σ) of constituent tissues. However, it is indeed unfortunate that worldwide there are very limited concerns regarding electromagnetic energy absorptions in plants, fruits and flowers - thus, no electromagnetic exposure regulatory guidelines have yet been put in effect to safeguard plants, crops, fruits and flowers. Thus, it is absolutely necessary to quantify microwave energy absorption rates in various fruit, flower and plant models due to electromagnetic radiations from different sources. Later on, consequent biological responses in plants along with associated effects on ecosystem and fruit nutrition value should be investigated. With this motivation, electromagnetic energy absorption rates i.e. SAR values along with associated spatial distributions have been estimated in this article for a typical Peace Lily (Spathiphyllum wallisii) plant model considering different frequencies of exposure, directions of plane wave incidence and polarizations of incident wave. Peace Lily plant has been chosen for this investigation as it is known for air purifying capability and indoor usage - furthermore, the plant parts can easily be characterized and modelled for electromagnetic simulations. Plants are of asymmetric shapes with varied sizes. To represent the typical geometric shape considering the most practical observation, a three dimensional Peace Lily plant model has been designed using CST Microwave Studio electromagnetic solver. The model has been exposed to linearly polarized plane waves at three distinct frequencies (947.50 MHz, 1842.50 MHz and 2450 MHz) following Indian electromagnetic exposure regulatory guidelines - these frequencies are used for voice, data or Wi-Fi communications. Dielectric properties (ε_r) i.e. permittivity (ε'_r) as well as loss tangent (tanδ) of different peace lily plant tissues have been characterized over a broad frequency band employing open ended coaxial probe measurement technique. Measured tissue dielectric properties (ε_r) have been fitted to the developed plant model to evaluate SAR data and spatial distributions. At each frequency, significant variations have been noted in magnitudes and positions of Maximum Local Point SAR (MLP SAR), 1 g averaged SAR and 10 g averaged SAR values for six different combinations of direction of arrival and incident wave polarization. Observations indicate different orders of change in MLP SAR, 1 g averaged SAR and 10 g averaged SAR values in the plant model even for same combination of frequency of exposure, power density, direction of arrival (plane wave) and polarization of incident wave. Data reported in this article can be considered as reference to investigate consequent physiological or molecular responses in plants and revise electromagnetic exposure regulatory policies to protect plants and the entire ecosystem.

This paper proposes a dual notches ultra-wideband (UWB) bandpass filter (BPF) with high selectivity and wide stopband. It is composed ofa novel multi-mode resonator (MMR) known as a double-T-shaped open stub-loaded MMR, a pair of interdigital coupled lines, and folded split ring resonator. The MMR is designed to place the resulting resonant modes within the UWB passband, then add interdigital coupled lines to achieve strong coupling, resulting in a flat passband. Afterward, multiple complimentary folded split ring resonators (CFSRRs) and folded split ring resonators (FSRRs) are embedded into the designed basic UWB filter to develop dual notches at the desired frequency. The filter is simulated and manufactured using low-cost high-frequency dielectric substrate F4BM. The measurement results agree well with the simulation data. Multiple notches centered on 5.8 and 8 GHz effectively suppress unwanted signals from 5.8 GHz WLAN and 8 GHz satellite systems simultaneously. In addition, two transmission zeros on both sides of the passband are located at 2.7 GHz and 10.76 GHz, respectively, so that the sharp skirt selectivity is improved to 0.857. The measured filter can exhibit high sharp selectivity and wider stopband at the same time.

In view of the problems of excessive magnetic flux leakage of the traditional permanent magnet fault-tolerant vernier rim-driven motor, low utilization rate of permanent magnets and high price of permanent magnet materials, this paper proposes a flux-concentrating consequent-pole permanent magnet fault-tolerant vernier rim-driven motor structure. Firstly, combined with the magnetic field modulation theory, the no-load air gap magnetic density of the motor is analyzed, and the working principle of the multi-harmonic operation of the motor is explained according to the harmonic analysis. Secondly, parametric modeling is used to screen the critical structural parameters that can significantly affect electromagnetic performance of the motor, and the response surface method and sensitivity analysis are used to rank the sensitivity of the critical parameters. Then, the high-sensitivity parameters are first subjected to multi-objective optimization, and then adjusted according to the low-sensitivity parameters. Finally, the air gap magnetic density, back- EMF, cogging torque and permanent magnet numbers of the motor before and after optimization are compared and analyzed by finite element analysis. The results show that the flux-concentrating consequent-pole permanent magnet vernier rim-driven motor has higher torque density, less torque ripple and higher utilization of permanent magnets.

In this paper, a compact, symmetric, simple, and highly selective Ultra Broad Band (UBB) Band Pass Filter (BPF) is constructed on a low-loss Taconic dielectric substrate. The top layer of the BPF is loaded with three headphone-shaped Defected Microstrip Structures (DMSs) and four Open Circuit (OC) stubs whereas the bottom layer is etched with three star-shaped Defected Ground Structures (DGSs). The proposed BPF is designed and simulated using High-Frequency Structure Simulator (HFSS) software at f₀. The proposed BPF shows 20 dB return loss and 0.4 dB insertion loss in the 3 dB passband covering 0.52 GHz to 17.1 GHz owing to 16.58 GHz Band Width (BW). Additionally, 10 dB and 25 dB upper stopband rejection is achieved with 1.3 GHz and 1 GHz BW respectively. Maximum group delay of the simulated filter is about 2.95 ns. The fabricated model transmits from 0.8 GHz to 17.4 GHz which in turn offers a 16.6 GHz BW at 3 dB level. The reflection coefficient of the fabricated filter is about -18 dB, and insertion loss varies from 0 dB to 0.72 dB inside the Transmission Band (TB) with a Fractional Band Width (FBW) of 178.5% and 3.35 ns maximum group delay. Moreover, the occurrence of Transmission Zeroes (TZs) and Reflection Poles (RPs) make the filter highly selective and low-loss (flatness). The measured results agree with the simulated outputs with slight deviations due to fabrication tolerances and connector loss. The size of the filter is 0.36λ_g * 0.36λ_g. Thus proposed filter is suitable for mobile phones, and satellite communication applications approximately covering L, S, C, X, and Ku frequency bands.

A systematic technique for switching between horizontal and vertical polarizations is introduced. A fan-beam antenna array for base station applications employing a grounded reflector is implemented, and the proposed approach is implemented and validated on it. The antenna array is realized using planar monopole elementary elements against a non-parasitic reflector, which yields a desirable fan-beam pattern. The corresponding 3 dB H-plane beamwidth can be easily adjusted by changing the reflector height. Two versions of the antenna arrays are used to demonstrate suppression of unwanted asymmetrical modes in the current distribution yielding improved cross-polar isolation. The measured H-plane 3-dB beamwidth is approximately 127 degrees at 900 MHz and 124 degrees at 955 MHz. The corresponding side lobe level is almost -11.7 dB and -8.7 dB at 900 MHz, while the back lobe level of -9.3 dB and -11 dB at 955 MHz from measurements. The gain is within the acceptable level in both cases and compared with simulations that possess good agreement. By taking into account the antenna design and manufacturing aspects, such antennas will pave the way to be employed in OFDM reconfigurable antenna applications and Identification Friend or Foe (IFF).