المؤلفون: Ewe, Wei-Bin¹ ewewb@ihpc.a-star.edu.sg, Koh, Dax Enshan¹ dax_koh@ihpc.a-star.edu.sg, Goh, Siong Thye¹ gohst2@ihpc.a-star.edu.sg, Chu, Hong-Son¹ chuhs@ihpc.a-star.edu.sg, Png, Ching Eng¹ pngce@ihpc.a-star.edu.sg

المصدر: IEEE Transactions on Microwave Theory & Techniques. May2022, Vol. 70 Issue 5, p2517-2525. 9p.

مصطلحات موضوعية: HELMHOLTZ equation, ELECTROMAGNETIC wave propagation, WAVEGUIDES, TRANSMISSION line matrix methods, FINITE difference method, LINEAR equations, LINEAR systems

مستخلص: Variational quantum algorithms (VQAs) are one of the most promising methods that can be implemented on noisy intermediate-scale quantum (NISQ) machines to achieve a quantum advantage over classical computers. This article describes the use of a VQA in conjunction with the finite difference method for the calculation of propagation modes of an electromagnetic wave in a hollow metallic waveguide. The two-dimensional (2-D) waveguide problem, described by the Helmholtz equation, is approximated by a system of linear equations, whose solutions are expressed in terms of simple quantum expectation values that can be evaluated efficiently on quantum hardware. Numerical examples are presented to validate the proposed method for solving 2-D waveguide problems. [ABSTRACT FROM AUTHOR]

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المؤلفون: Michalski, Krzysztof A., Mustafa, Mazin M.

المصدر: IEEE Transactions on Microwave Theory & Techniques. Sep2018, Vol. 66 Issue 9, p3981-3992. 12p.

مصطلحات موضوعية: *TELECOMMUNICATION systems, ELECTROMAGNETIC wave propagation, RADIATIVE transfer, ELECTROMAGNETIC waves, SIGNAL quantization

مستخلص: A robust and efficient method is presented for the computation of the electromagnetic modes supported by planar multilayer waveguides that may comprise lossy, active, plasmonic, and uniaxial media, including graphene sheets. Pole-free and numerically stable dispersion functions (DFs) are developed for various shielding configurations using the $S$ -matrix formulation. The modal propagation constants are computed by the Cauchy integration method on the four-sheeted Riemann surface, using the derivative of the DF for greater reliability. Since analytical derivatives of the S-parameters are difficult to obtain, automatic differentiation is employed, implemented by operator overloading in modern Fortran. The method is validated using various benchmark problems found in the literature. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Zhang, Ruonan¹, Zhou, Yuliang¹, Lu, Xiaofeng², Cao, Chang², Guo, Qi¹

المصدر: IEEE Transactions on Microwave Theory & Techniques. Oct2017, Vol. 65 Issue 10, p3648-3659. 12p.

مصطلحات موضوعية: *MATHEMATICAL models, EMBEDDING theorems, MILLIMETER wave propagation, RADIO wave propagation, MEASUREMENT of millimeter waves, ELECTRIC field strength, ANTENNA radiation patterns, MULTIPATH channels

مستخلص: In field measurements at millimeter-wave (mmWave) frequencies, the spatial propagation characteristics are usually obtained by using steerable high-gain horn antennas to compensate the large path loss. However, it is a challenging issue to deembed antenna patterns from the observed channel responses. This paper has two contributions. First, according to the steering-antenna sounding process, a spatial channel response model is designed, where the multipath propagation profile, antenna pattern, and channel response are spatially sampled and combined in a discrete convolutional form. Then, a low-complexity antenna deembedding algorithm, including two steps of deconvolutions, is proposed. Second, a field measurement campaign on the frequency-space mmWave channels in an office is presented to validate the method. The channels were sounded at 72.5 to 73.5 GHz using three horn antennas with different beam widths and gains. The omnidirectional angular channel responses (ACRs) were measured by rotating the receiver antenna. The observed and reconstructed ACRs are consistent, and the estimated antenna-free angular propagation profiles by using different horn antennas are also highly correlated, which validate the proposed antenna deembedding approach. Furthermore, the omnidirectional transfer functions in the mmWave band obtained using different horn antennas are compared, and the channel coherence bandwidth is analyzed based on the autocorrelation of the transfer functions. [ABSTRACT FROM PUBLISHER]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Kong, Fanpeng¹, Ghovanloo, Maysam¹, Qi, Cheng², Durgin, Gregory D.², Lee, Hoseon³

المصدر: IEEE Transactions on Microwave Theory & Techniques. May2018, Vol. 66 Issue 5, p2546-2555. 10p.

مصطلحات موضوعية: ASSISTIVE technology, RADIO wave propagation

مستخلص: The intraoral Tongue Drive System (iTDS), is a tongue-controlled wireless assistive technology, operated by a number of user-defined voluntary tongue gestures to issue control commands. In this paper, we present a new arch-shaped iTDS, occupying the buccal shelf space in the mouth, without limiting the available space for tongue motions. We describe the design, characterization, and comparison between three types of 2.4-GHz antennas for this system: patch, dipole, and planar inverted-F in terms of gain, directivity, bandwidth, and data communication performance to achieve a robust RF link despite mouth motions. The antennas are designed and simulated in a simple human mouth model and measured in the mouth. Based on simulation and measurement results, using an iTDS prototype made of commercial-off-the-shelf components, the patch antenna has the highest gain in both closed- and open-mouth states, at −10.6 and −9 dBi, respectively. We also measured the propagation loss between the iTDS intraoral antenna and out-of-mouth receiver (Rx) in a real user-case scenario and evaluated the link quality by measuring the packet error rate between the transmitter and RX. The presented antennas have larger bandwidth, smaller area, and higher gain compared to prior work on implantable antennas in the literature, resulting in a robust wireless link for the iTDS application. [ABSTRACT FROM PUBLISHER]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Yamauchi, Junji¹, Ueda, Tetsuya¹, Kubo, Yuki¹, Itoh, Tatsuo²

المصدر: IEEE Transactions on Microwave Theory & Techniques. Dec2017, Vol. 65 Issue 12 Part2, p5123-5132. 10p.

مصطلحات موضوعية: METAMATERIALS, ELECTROMAGNETIC wave propagation, MICROSTRIP transmission lines, PERMEABILITY measurement, BESSEL functions

مستخلص: A new approach to enhance the phase-shifting nonreciprocity of microstrip-line-based metamaterials with normally magnetized ferrite substrates is proposed, by using a combination of curvature of the lines and asymmetric insertion of stubs. In the analytical approach, the nonreciprocity is approximately formulated by introducing asymmetric surface admittance on the side walls at the strip edges, showing that a linear combination of two factors due to the line curvature and the difference of asymmetric admittances contributes to geometrical asymmetry of the wave-guiding structures. Numerical simulation and measurement results verify predictions from the analytical approach. It is demonstrated that a combination of larger curvature of the metamaterial lines and hybrid insertion of inductive and capacitive stubs on the inner and outer sides, respectively, provides significant enhancement of the nonreciprocity compared to the single side insertion of stubs. [ABSTRACT FROM PUBLISHER]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Samimi, Mathew K.¹, Rappaport, Theodore S.¹

المصدر: IEEE Transactions on Microwave Theory & Techniques. Jul2016 Part 2 Part 2, Vol. 64 Issue 7b, p2207-2225. 19p.

مصطلحات موضوعية: *5G networks, *IMPULSE response, *WIRELESS communications, MILLIMETER wave propagation, MULTIPATH channels, ANTENNA arrays

مستخلص: This paper presents a 3-D statistical channel impulse response (IR) model for urban line of sight (LOS) and non-LOS channels developed from 28- and 73-GHz ultrawideband propagation measurements in New York City, useful in the design of 5G wireless systems that will operate in both the ultra-high frequency/microwave and millimeter-wave (mmWave) spectrum to increase channel capacities. A 3GPP-like stochastic IR channel model is developed from measured power delay profiles, angle of departure, and angle of arrival power spectra. The extracted statistics are used to implement a channel model and simulator capable of generating 3-D mmWave temporal and spatial channel parameters for arbitrary mmWave carrier frequency, signal bandwidth, and antenna beamwidth. The model presented here faithfully reproduces realistic IRs of measured urban channels, supporting air interface design of mmWave transceivers, filters, and multi-element antenna arrays. [ABSTRACT FROM PUBLISHER]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Feng, Guoxu, Huang, Jun, Su, Hongbo

المصدر: IEEE Transactions on Microwave Theory & Techniques; Apr2022, Vol. 70 Issue 4, p2040-2052, 13p

مصطلحات موضوعية: RAY tracing, CONFORMAL mapping, ELECTROMAGNETIC wave propagation, REFRACTIVE index, HOUGH transforms

مستخلص: We put forward a new ray tracing method for electromagnetic wave propagation based on piecewise conformal transformations. Our approach is based on our previous research, where conformal transformation was focused on giving an accurate formula for the effective Earth radius. In this article, according to the height interval of atmospheric refractive index data, we approximate the electromagnetic wave propagation path by the combination of circular arcs with different curvature radius and find the effective Earth radius of each arc using conformal transformations. Then, upon using the effective Earth radius, we transform the circular arc path into a straight path, thus simplifying the calculations needed to describe the propagation of electromagnetic waves. We compare our approach to the traditional ray tracing method for several typical atmospheric refractive index profiles and prove that our new method may achieve ray tracing with higher accuracy using fewer path points. We also consider nonuniform atmosphere and irregular terrain and compare the performance of our ray tracing scheme with that of the open-source software PETOOL, which is based on the parabolic equation method. Result proves that the new method may be effectively used for ray tracing in complex environments. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Correas-Serrano, D.¹, Gomez-Diaz, J. S.², Perruisseau-Carrier, J.², Alvarez-Melcon, A.¹

المصدر: IEEE Transactions on Microwave Theory & Techniques. Dec2013 Part 2, Vol. 61 Issue 12, p4333-4344. 12p.

مصطلحات موضوعية: SURFACE waves (Fluids), RADIO wave propagation, OPTICAL properties of graphene, ELECTRIC conductivity, WAVEGUIDES -- Design & construction, PLASMONS (Physics)

مستخلص: The propagation of surface waves along spatially dispersive graphene-based 2-D waveguides is investigated in detail. Graphene is characterized using a full-k_\rho conductivity model under the relaxation-time approximation, which allows to obtain analytical and closed-formed expressions for the wavenumber of plasmons supported by sheets and parallel plate waveguides, respectively. Per unit length equivalent circuits are introduced to accurately characterize the propagation in different waveguides, and analytical relations between the effective TM-mode circuit lumped elements and graphene conductivity are derived. The proposed circuits allow identifying the different mechanisms involved in spatially dispersive plasmon propagation, explaining their connection with the intrinsic properties of graphene. Results demonstrate that spatial dispersion, which significantly decreases the confinement and the losses of slow surface plasmons, must be accurately assessed in the design of graphene-based plasmonic components at millimeter-waves and low terahertz frequencies. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المصدر: IEEE Transactions on Microwave Theory & Techniques. Oct2012, Vol. 60 Issue 10, pC1-C4. 4p.

مصطلحات موضوعية: ELECTROMAGNETIC wave propagation, NEMATIC liquid crystals

مستخلص: Presents the cover/table of contents for this issue of the periodical. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Polycarpou, A. C.¹, Christou, M. A.², Papanicolaou, N. C.²

المصدر: IEEE Transactions on Microwave Theory & Techniques. Oct2012, Vol. 60 Issue 10, p2950-2958. 9p.

مصطلحات موضوعية: ELECTROMAGNETIC wave propagation, NUMERICAL analysis, NEMATIC liquid crystals, MAXWELL equations, ELECTROMAGNETIC theory, ELECTRIC fields

مستخلص: In this paper, we present a computationally efficient and highly accurate numerical method for the analysis of electromagnetic wave propagation in nematic liquid crystal (N-LC) cells. An iterative procedure is employed where the mode-matching technique (MMT) is used to solve the time-harmonic Maxwell equations inside the N-LC cell, whereas a finite-difference method (FDM) with relaxation is utilized to treat the nonlinear stationary Ginzburg-Landau equation for the director field. The angular distortion of the directors in the N-LC cell depends on the applied electric field which, in turn, affects the anisotropic dielectric properties of the medium. Numerical results are obtained for various values of the governing parameters. These simulations provide further insight into the Fréedericksz transition with special emphasis on resonances, bi-stability, hysteresis, phase shift between ordinary and extraordinary waves (birefringence), and soft anchoring effects. Obtained results are compared and validated against measurements and data published in the literature. [ABSTRACT FROM AUTHOR]

: Copyright of IEEE Transactions on Microwave Theory & Techniques is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)