There is no doubt that electrified vehicles are superseding internal combustion engine vehicles for road transportation. Among them, electric vehicles (EVs) have been identified as the greenest road transportation while hybrid EVs have been tagged as the super ultra-low emission vehicles. In this paper, the definition, classification, merits and demerits of electric and hybrid vehicles are first introduced. Then, after revealing their multidisciplinary technologies and development trends, the state-of-the-art electromagnetics research in electric and hybrid vehicles are discussed, with emphasis on electric motors for electric propulsion, electric machine systems for hybrid propulsion, wireless power transfer technologies for park-and-charge a well as move-and-charge, electromagnetic interference and compatibility issues in EVs, electromechanical flywheels for energy storage and magnetic sensors for EV operation. Meanwhile, the development trend of these research areas is revealed.
A magnetic resonance imaging (MRI) duodenoscope is demonstrated, by combining non-magnetic endoscope components with a thin-film receiver based on a magneto-inductive waveguide. The waveguide elements consist of figure-of-eight shaped inductors formed on either side of a flexible substrate and parallel plate capacitors that use the substrate as a dielectric. Operation is simulated using equivalent circuit models and by computation of two- and three-dimensional sensitivity patterns. Circuits are fabricated for operation at 127.7 MHz by double-sided patterning of copper-clad Kapton and assembled onto non-magnetic flexible endoscope insertion tubes. Operation is verified by bench testing and by 1H MRI at 3T using phantoms. The receiver can form a segmented coaxial image along the length of the endoscope, even when bent, and shows a signal-to-noise-ratio advantage over a surface array coil up to three times the tube diameter at the tip. Initial immersion imaging experiments have been carried out and confirm an encouraging lack of sensitivity to RF heating.
Illumination optics in emerging naked-eye 3D display, especially in time-spatial multiplexing, or directional backlight naked-eye 3D display system, is systematically examined. Key issues in directional backlight system include: 1) Directional transmission of the left- and right-eye images to the corresponding viewing zone with small crosstalk; 2) The luminance on the screen should be homogeneous even for the viewers moving around. In this paper, we propose an adaptive optimization solution based on root mean square (RMS) for the design of illumination optics of the naked-eye 3D system. Based on the designed free-form backlight illumination, the overall design schemes for both single-user and multi-user naked-eye 3D display are proposed and demonstrated. By utilizing the novel dynamic synchronized backlight technique, the temporal crosstalk is effectively brought into control. The display defects such as the dark bands appearing at the joints of the lens array or at the middle of the Fresnel lens are simulated numerically and tested experimentally, hence providing effective design guidelines for the optical components as well as their fabrication error tolerance. Additionally, we propose a continuous backlight technique to improve the luminance homogeneity. Furthermore, a quantitative evaluation mechanism for the moiré pattern based on the Fourier analysis method, by introducing the contrast sensitivity function (CSF), is presented. A novel arrangement of a quasi-random RGB sub-pixel array is proposed to reduce the visibility of moiré pattern. As a result, full HD glassless 3D display suitable for glassless virtual and augmented realities is demonstrated with an unprecedented display quality.
An X/Ku-band flat lens antenna based on dual-frequency anisotropic metasurface is proposed in this paper. The function of the anisotropic metasurface is to focus the incident plane waves around 10 GHz and 14 GHz on different spots. Then we place a Vivaldi antenna with its phase centers at 10 GHz and 14 GHz well matching the focal spot of the metasurface at each frequency to build a flat lens antenna. The lens antenna has a peak gain of 18.5 dB and cross-polarization levels of lower than -20 dB at 10 GHz with -1 dB gain bandwidth of 9.8-10.4 GHz, while it has a peak gain of 18.8 dB and cross-polarization levels of lower than -30 dB at 14 GHz with the bandwidth of 13.8-14.2 GHz. Besides single working band, the antenna can simultaneously operate at 10 GHz and 14 GHz with gains of 16.2 dB and 16.5 dB, respectively. Measured results have a good agreement with the simulated ones.
A self-contained electromagnetic theory is developed on a simplicial lattice. Instead of dealing with vectorial field, discrete exterior calculus (DEC) studies the discrete diff erential forms of electric and magnetic fields, and circumcenter dual is adopted to achieve diagonal Hodge star operators. In this paper, Gauss' theorem and Stokes' theorem are shown to be satisfi ed inherently within DEC. Many other electromagnetic theorems, such as Huygens' principle, reciprocity theorem, and Poynting's theorem, can also be derived on this simplicial lattice consistently with an appropriate defi nition of wedge product between cochains. The preservation of these theorems guarantees that this treatment of Maxwell's equations will not lead to spurious solutions.
In a previous work, improved full-wave analytical expressions have been derived for the Sommerfeld Integrals (SIs) describing electromagnetic radiation from a short vertical straight wire located in close proximity to a conductive soil. Such formulas ensure high accuracy of the result of the computation, as well as time savings with respect to conventional techniques used to evaluate the SIs, but unfortunately may be used only when both source and field points are located at the air-medium interface. The scope of this paper is to overcome the limitations implied by the previous approach, and provide series-form expressions for the generated field components that are valid for an arbitrarily stratified medium and for any position of the vertical wire antenna and observation point in the air space above it. The expressions follow from the analytical evaluation of the integral representation for the magnetic vector potential, performed through contour integration after substituting an equivalent pole set for each branch cut of the integrand. Validity, efficiency and accuracy of the developed formulas are illustrated through numerical examples.
In this paper, we study the design and homogenization of bianisotropic metamaterials originated from planar split-ring resonators, which would potentially meets the requirements of the emerging photonic topological insulators and some other types of extotic photonic materials with non-trivial states. We show that the off-diagonal elements in the magneto-electric tensor can be realized by combining the planar split-ring resonators with different orientations. To ease the fabrication process, a layer-bylayer design of metamaterials with desired bianisotropy is proposed. The design and homogenization procedure of such metamaterials are verified through effective parameter retrieval approach and computer based simulation. With the proposed structure, the complex magneto-electric coupling is realized in layered structures through planar techniques, which may be useful in the terahertz and optical range.
This paper presents a design of multi-band array antenna based on Double Negative Metamaterial (DNM) unit cells for multi-automotive applications. The antenna consists of 4×4 rectangular and circular radiating patches connected in series using microstrip lines and fed by a 50 Ω corporate microstrip line. An array of 4×6 wire loaded complementary spiral resonator (CSR) unit cells is placed on its reverse side to provide miniaturization and multiband features to the proposed design. The reflection coefficient (S11), mutual coupling, effective diversity gain (EDG), envelope correlation coefficient (ECC), and radiation patterns are evaluated for four elements of the proposed antenna placed in four different locations on the car body model. Simulations and measurements indicated that the proposed antenna features a low mutual coupling (<-34 dB), low ECC (<0.0001), high EDG (>9.99), high efficiency (72%-95%), and low on-car detuning over the operating frequency bands. The proposed antenna covers five bands; 1.99 GHz to 3.03 GHz, 5.15 GHz to 6.369 GHz, 7.67 GHz to 7.99 GHz, 9.91 GHz to 10.23 GHz, and 11.79 GHz to 12.2 GHz. The performance of ECC between four antennas on car body has been investigated in different cases of isotropic, indoor, and outdoor. The metallic effect on antennas performance also has been investigated by evaluating the mutual coupling and transmission coefficient between two antennas served as transmitter and receiver with presence of car body. The results show transmission coefficient of proposed DNM antenna with metallic presence almost identical to free space across desired frequency bands. With all capabilities mentioned the antenna has potential for WiFi/WiMAX, Vehicle-to-Vehicle (V2V), transportable earth exploration satellite, military requirement for land vehicles, and earth stations on vessels applications.
A compact coplanar waveguide (CPW) fed close ring resonator (CRR) loaded four-element metamaterial (MTM) array antenna for wireless application is designed and discussed in this article. The array is designed with corporate feeding network, arranged in a manner to offer 3 dB power at its each element. The proposed 1×4 MTM array antenna offers a fractional bandwidth of 10.18% with respect to the resonance frequency of fr = 2.26 GHz. At the resonance frequency of 2.26 GHz, the proposed 1×4 MTM array antenna offers a gain of 5.10 dBi in the direction of broadside radiation. Each element of the proposed array antenna consists of CRR, which removes the requirement of via and allows the design of a uniplanar MTM array. The overall electrical size of the single element antenna shows compactness of 0.255λ0 × 0.155λ0 × 0.012λ0, where λ0 is the free space wavelength at its resonance frequency of fr = 2.3 GHz. The proposed MTM array antenna is designed, and simulated on ANSYS HFSS 14.0 and simulated results are verified with the fabricated proto-type.
Design and characterization of a multilayered compact implantable broadband antenna for wireless biotelemetry applications is presented in this paper. The main features of this novel design are miniaturized size, structure that allows integration of electronic circuits of the implantable medical device inside the antenna, and enhanced bandwidth that mitigates possible frequency detuning caused by heterogeneity of biological tissues. Using electromagnetic simulations based on the finite-difference time-domain method, the antenna geometry was optimized to operate in the 401-406 MHz Medical Device Radio communications service band. The proposed design was simulated implanted in a muscle tissue cuboid phantom and implanted in the arm, head, and chest of a high-resolution whole-body anatomical numerical model of an adult human male. The antenna was fabricated using low-temperature co-fired ceramic technology. Measurements validated simulation results for the antenna implanted in muscle tissue cuboid phantom. The proposed compact antenna, with dimensions of 14 mm × 16 mm × 2 mm, presented a -10 dB bandwidth of 103 MHz and 92 MHz for simulations and measurements, respectively. The proposed antenna allows integration of electronic circuit up to 10 mm × 10 mm × 0.5 mm. Specific absorption rate distributions, antenna input power, radiation pattern and the transmission channel between the proposed antenna and a half-wavelength dipole were evaluated.
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