From the perspective of motor control and manufacturing process, the application of fault-tolerant permanent magnet rim driven motor (FTPM-RDM) in shaftless rim driven thruster (RDT) can avoid the complicated shafting structure in traditional propulsion system effectively, and realize the sensorless control while reducing volume. Referring to the fault-tolerant structure features, this paper introduces an improved sensorless control algorithm based on two-stage second-order generalized integral (SOGI) pulsating high-frequency (HF) voltage injection which is applied to the FTPM-RDM in zero and low speed. This algorithm can realize the rotor position estimation under fault and healthy condition. Based on pulsating HF injection method, HF square-wave voltages are injected in the virtual dq axis, and the initial rotor position can be extracted from the response currents of stationary reference frame (SRF). The sinusoidal voltage is injected into the virtual $dq$ axis, and use two-stage SOGI instead of the traditional filter is used to realize the current modulation without delay in low speed rotor position estimation. Combining the simulation and experiments, the proposed sensorless control strategy can estimate the rotor position accurately whether in failure or not and has good dynamic and static performance.
In this paper, a novel design concept that uses multi-layer metasurface structures to design and develop bandpass filter screens is proposed. The unique proposition of the work lies in the control of transmission bandwidth of such metasurface screens, which has been obtained by sequential arrangement of unit cell layers, that comprise of Minkowski fractal-shaped unit cells and its complement. This reconfigurability of the structure is achieved without changing the geometry of the unit cell design, rather by stacking the layers in different configurations, or even by changing the substrate thickness, leading to the capability to obtain either narrowband or broadband filtering screens as per the requirement. An equivalent circuit model is proposed to explain such behaviour. Two configurations of stacked complementary surfaces, namely the Patch-Slot-Patch (PSP) and the Slot-Patch-Slot (SPS) designs have been investigated. The PSP structure on a thinner dielectric substrate offered dual band resonance with distinguishable transmission peaks, whereas the same configuration on substrate of increased thickness offered wider transmission bandwidth (45.5% to 50.5% percentage bandwidth). In comparison, the SPS structure offered much narrower transmission bandwidth (varies between 4.7% to 8.16%). The effect of changing the periodicity of the unit cell elements, without altering the fractal unit cell dimensions, has been described, through which one can control the band of operation and roll-off performance of the screens. The simulation results are found to be in good agreement with the measured results of the fabricated prototypes.
In this paper, a planar microstrip patch antenna operating in FCC MBAN for tumor detection is presented. The proposed antenna is constructed using a triangle-shaped patch with inset feeding. It is fabricated on an Arlon AD1000 substrate. Some of the parameters are assumed, and optimization is carried out to achieve greater performance. This prototype is placed on a human tissue mimicking model and simulated considering the cases of body model with tumor and without tumor. The designed antenna resonates at 2.37 GHz with 10 dB bandwidth of 3 MHz meeting the requirements specified by the FCC. Further, the introduction of a slot in the ground plane gives a half power beam width of 20.6° with directivity of 8 dB. This narrow beam is suitable for scanning application in microwave imaging. The fabrication of the antenna is carried out, and measurements are done to assess the performance of the antenna. Body phantom is created using petroleum jelly and mixture of wheat flour and water. The fabricated antenna is placed on the created model, and the variation in the resonant characteristics has been observed with the presence and absence of tumor.
With the gradual popularization of high-power electric vehicle wireless power transfer (EV-WPT) applications, the safety issue of human exposure to electromagnetic fields leaked from EV-WPT devices has received considerable attention. In particular, careful attention should be devoted to human protection from electromagnetic field issues among people with medical implants. Considering the electromagnetic coupling between a human aortic valve metal stent (AVS) and the leakage field, this study establishes a numerical simulation model of the electromagnetic exposure of a human implanted with AVS to the leakage electromagnetic field of EV-WPT on the basis of human medical ethics. Given the existence of many uncertainties in actual WPT charging, which may cause damage to a human heart implanted with AVS, an orthogonal matching pursuit sparse generalized polynomial chaos expansion (OMP-sgPCE) method is developed to conduct an uncertainty quantification of the maximum induced electric field intensity (Emax) of a human heart implanted with AVS. Results indicate that the induced Emax obtained by this method can exceed the ICNIRP guideline limit and may seriously endanger human heart safety. This study also adopts the Sobol method to obtain the degree of influence of the coil group's spatial location parameters and the AVS geometric parameters on the induced Emax, thereby providing a reasonable theoretical basis and scientific guidance for the optimal design of EV-WPT devices and AVS.
We propose a compact dual-band MIMO antenna for GSM 1800 MHz and WLAN applications. A novel single branch dual band antenna consisting of a quarter annular ring and an inverted U-shaped strip is designed by decreasing the electromagnetic coupling between higher order modes of an annular ring ultra-wideband (UWB) antenna, and a simple technique of slots and I and L-shaped stubs protruding from ground plane is employed to achieve high isolation. S11 < -10 dB over 1.704-1.934 GHz and 5.66-6.25 GHz frequency range and mutual coupling S12 < -20 dB and < -28 dB over the two bands are achieved. The radiation pattern, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), diversity gain (DG), and mean effective gain (MEG) conform to MIMO specifications. The prototype antenna is fabricated on a 0.244λ0 × 0.17λ0 FR4 substrate, where λ0 is the free-space wavelength at 1.7 GHz. The antenna offers stable radiation patterns. The antenna is compact, simple to design, easy to fabricate, and low in cost. These characteristics depict the suitability of this antenna for portable wireless devices.
Flux reversal permanent magnet machine (FRPMM) has been widely used because of its high efficiency, simple structure and high fault tolerance. However, the torque of the FRPMM is restricted by its longer equivalent length of air gap. To further improve its torque density, this paper presents two novel FRPMMs with auxiliary teeth and different magnetization modes. Both machines use auxiliary teeth without permanent magnet (PM), and both machines have three PM blocks on each main tooth. The difference of two machines is that they have different order of arrangement of PM. The design parameters of two machines are optimized based on genetic algorithm (GA). Finally, the back EMF and torque of the two machines are compared with the conventional FRPMM to show the superiority of the two machines. At the same time, the other important performances of the two machines are compared and analyzed, and their respective advantages and disadvantages are obtained as a reference for selecting the respective appropriate application scenarios.
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.
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, 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.
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 (εr) 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 (εr) 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 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 0.36λg * 0.36λg. Thus proposed filter is suitable for mobile phones, and satellite communication applications approximately covering L, S, C, X, and Ku frequency bands.
This paper presents a forthcoming compact high-performance two-element multiple-input-multiple-output (MIMO) diverse antenna for wireless-LAN 5 GHz band and sub-6 GHz 5G(NR) band. The proposed antenna consists of two symmetrical antenna elements with an inverted T-shaped ground structure. The antenna attributes such as S-parameters, realized gain, current distribution, and radiation patterns are studied. Additionally, MIMO performance is also investigated in terms of envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and multiplexing efficiency. The antenna covers the entire 5G band for wireless communication, with an effective band (-10-dB) of 2.92 to 5.72 GHz (provides bandwidth of 2.8 GHz). The obtained values indicate that measured performance is in reasonable agreement with simulated one. Additionally, efficiency and gain were around 95 % and above 3 dB across the band of interest respectively.
In this paper, a low-profile triple-notched bandstop filter (BSF) is introduced. The proposed filter suppresses frequencies of Bluetooth (2.4 GHz), Wi-Max (3.5 GHz), and Wi-Fi (5.2 GHz) using three defected microstrip structures (DMSs). This BSF may be located in the feed line of an ultra-wideband (UWB) antenna. Consequently, not only the complexity is reduced, but also the area of the presented filter (24×10 mm2) is plummeted. Multiple rectangular slots are etched in the feed line to achieve multi-notch performance. Additionally, two dumbbell-shaped defected ground structures (DGSs) are etched in the ground plane to improve matching. Three PIN diodes are used to reconfigure the frequency response of the filter. By controlling the three diodes, the proposed filter can support six operating modes. The filter is simulated, optimized, fabricated, and measured to be suitable for cognitive radio applications. It achieves an insertion loss of (40, 29, and 24) dB and a rejection rate of (184, 215, and 277) dB/GHz at 2.4, 3.5, and 5.2 GHz, respectively. The simulated and measured results agree well.
This article introduces a new planar multiband antenna inspired by metamaterials. The design incorporates a split-ring resonator (SRR) on a printed monopole antenna for ultra-wideband (UWB) communication, generating a new resonant frequency within the Industrial, Scientific, and Medical (ISM) frequency band. The effect of SRR-inspired slots was examined using characteristic mode analysis (CMA), revealing that the placement of the SRR on the antenna's radiating structure created multiple resonant modes. To improve impedance matching, the ground plane of the antenna was modified. The antenna was fed using a 50 Ω microstrip line. The proposed antenna was simulated and fabricated on an inexpensive FR4 substrate with a thickness of 1.6 mm, a dielectric constant of 4.4, and dimensions of 38×40 mm2. To validate the simulation results, the antenna parameters were measured. The results showed that the proposed antenna is capable of covering both the ISM frequency band (2.2-2.5 GHz) and the UWB frequency band (3-26 GHz). This makes it suitable for various wireless communication applications requiring UWB and ISM frequencies, offering a promising solution.