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Journal articles on the topic 'LEAKY WAVEGUIDE'

Author: Grafiati

Published: 11 September 2023

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1

Kanaya, Yusho, Masashi Nakatsugawa, Tamami Maruyama, Manabu Omiya, and Yasuhiro Tamayama. "FDTD Analysis on WPT Efficiency Between Circuit-Shape Leaky Waveguide and 𝝀/2 Dipole Antenna for Snow Melting Application." ELEKTRIKA- Journal of Electrical Engineering 21, no. 2 (August 25, 2022): 82–85. http://dx.doi.org/10.11113/elektrika.v21n2.409.

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The wireless transfer characteristics between a circuit-shape leaky waveguide and a /2 dipole antenna were analyzed with scattering parameters obtained with the FDTD method. The circuit-shaped leaky waveguide was composed of two pairs of straight slotted waveguides and two semicircular waveguides. The circuit-shape leaky waveguide was designed to achieve uniform electromagnetic field distribution with a source for snow melting with microwave radiations by microwave heating. The electromagnetic field of the circuit-shape leaky waveguide was firstly simulated with the FDTD method. Although the electromagnetic distribution exhibited the point symmetry with an off-set feeding point and a slot spacing 𝝀𝒈, it was nearly uniform. The wireless transfer efficiency and the maximum transfer efficiency for four locations at 2.45 GHz revealed that the farthest location from the feeding point had the largest WPT efficiency among four locations. This ensures the circuit-shape leaky waveguide’s uniqueness. The circuit-shape leaky waveguide has favorable characteristics to provide WPT energy at any location above it.

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2

Divakov, Dmitriy V., Alexandre A. Egorov, Konstantin P. Lovetskiy, Leonid A. Sevastianov, and Andrey S. Drevitskiy. "Leaky waves in planar dielectric waveguide." Discrete and Continuous Models and Applied Computational Science 27, no. 4 (December 15, 2019): 325–42. http://dx.doi.org/10.22363/2658-4670-2019-27-4-325-342.

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A new analytical and numerical solution of the electrodynamic waveguide problem for leaky modes of a planar dielectric symmetric waveguide is proposed. The conditions of leaky modes, corresponding to the Gamow-Siegert model, were used as asymptotic boundary conditions. The resulting initial-boundary problem allows the separation of variables. The emerging problem of the eigen-modes of open three-layer waveguides is formulated as the Sturm-Liouville problem with the corresponding boundary and asymptotic conditions. In the case of guided and radiation modes, the Sturm-Liouville problem is self-adjoint and the corresponding eigenvalues are real quantities for dielectric media. The search for eigenvalues and eigenfunctions corresponding to the leaky modes involves a number of difficulties: the problem for leaky modes is not self-adjoint, so the eigenvalues are complex quantities. The problem of finding eigenvalues and eigenfunctions is associated with finding the complex roots of the nonlinear dispersion equation. To solve this problem, we used the method of minimizing the zero order. An analysis of the calculated distributions of the electric field strength of the first three leaky modes is given, showing the possibilities and advantages of our approach to the study of leaky modes.

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3

Smalley, Daniel E., Sundeep Jolly, Gregg E. Favalora, and Michael G. Moebius. "Status of Leaky Mode Holography." Photonics 8, no. 8 (July 21, 2021): 292. http://dx.doi.org/10.3390/photonics8080292.

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It will soon be a decade since leaky mode waveguide devices were presented as a solution for holographic video displays. This paper seeks to provide a brief, topical review of advances made during that time. Specifically, we review the new methods and architectures that have been developed over this period. This work draws primarily from papers seeking to present dynamic holographic patterns using mode coupling from indiffused waveguides on lithium niobate. The primary participants during this time period have been groups from the Massachusetts Institute of Technology, Brigham Young University, and Draper. We also describe the challenges that remain. The body of work reviewed speaks to the need for further development, but it also reaffirms that leaky mode waveguides continue to hold a unique place within spatial light modulation for holographic video displays.

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4

Ayryan, Edik, Dmitry Divakov, Alexandre Egorov, Konstantin Lovetskiy, and Leonid Sevastianov. "Modelling Leaky Waves in Planar Dielectric Waveguides." EPJ Web of Conferences 226 (2020): 02003. http://dx.doi.org/10.1051/epjconf/202022602003.

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Experimentally observed leaky modes of a dielectric waveguide are characterised by a weak tunnelling of the light through the waveguide and its long-time propagation along the waveguide. Traditional mathematical models of leaky waveguide modes meet some contradictions resolved using additional considerations. We propose a model of leaky modes in a waveguide free from the above contradictions, akin to the quantum mechanical model of the “pseudo-stable” Gamow-Siegert states. By separating variables, from the complete problem for plane inhomogeneous waves we obtain a non-self-adjoint Sturm-Liouville problem to determine the complex coefficient of the phase delay of the studied mode. The solution of the complete wave problem determines the propagation cone for the leaky mode of the waveguide, inside which there are no contradictions. Thus, solution is in qualitative agreement with experimental data.

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5

Mann, M., U. Trutschel, F. Lederer, L. Leine, and C. Wächter. "Nonlinear leaky waveguide modulator." Journal of the Optical Society of America B 8, no. 8 (August 1, 1991): 1612. http://dx.doi.org/10.1364/josab.8.001612.

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6

Vaupel, Thomas, and Claudius Löcker. "Design of leaky-wave antennas with transverse slots for end-fire radiation with optimized radiation efficiency." Advances in Radio Science 17 (September 19, 2019): 71–75. http://dx.doi.org/10.5194/ars-17-71-2019.

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Abstract. A substrate integrated waveguide (SIW) with transverse slots on the top plane can be used to design an effective leaky-wave antenna with good frequency beam-scanning and platform integration capability. For a main beam near end-fire, the phase constant of the radiating wave must be near to the free space wavenumber or slightly larger. In this context, the modified Hansen-Woodyard condition gives an optimum phase constant to maximize the directivity at end-fire. For the analysis of the wave propagation we have implemented a modal analysis for rectangular waveguides with transverse slots. Near end-fire, three types of modal solutions exists, a leaky improper mode, a surface wave mode and a proper waveguide mode. The leaky mode can reach phase constants larger than the free space wavenumber to fulfill the Hansen-Woodyard condition, but loses strongly its physical significance in this slow wave region, thus the excitation of the leaky-wave becomes negligible there, whereas the proper waveguide mode is dominant but exhibits only a negligible radiation loss leading to a strong drop of the antenna efficiency. Therefore, the optimum efficiency of 86 % for maximizing the gain as proposed in the literature cannot be reached with this kind of leaky wave antenna. But it will be shown in this contribution by analyzing antenna structures with finite aperture lengths, that the efficiency can reach nearly 100 % if the phase constant of the leaky-wave meets exactly the free space wavenumber (ordinary end-fire condition) and the aperture length is adjusted with regard to the attenuation constant of the leaky-wave from the modal analysis. For a given aperture length, a procedure is outlined to adjust the attenuation constant in several steps at the desired ordinary end-fire frequency to reach maximum gain and efficiency.

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7

Malakhov, Vasiliy A., Irina V. Malakhova, Artyom S. Nechaev, Artyom A. Nikitin, and Yulia V. Raevskaya. "Experimental studies of the E01 leaky wave characteristics in a round dielectric rod." ITM Web of Conferences 30 (2019): 11003. http://dx.doi.org/10.1051/itmconf/20193011003.

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Excitation experiment technique of the E01 leaky wave in a round open dielectric waveguide is given. Experimental research results of the E01 leaky wave characteristics of a round open dielectric waveguide are presented.

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8

Divakov, Dmitriy, Anastasiia Tiutiunnik, and Anton Sevastianov. "Symbolic-Numeric Computation of the Eigenvalues and Eigenfunctions of the Leaky Modes in a Regular Homogeneous Open Waveguide." MATEC Web of Conferences 186 (2018): 01009. http://dx.doi.org/10.1051/matecconf/201818601009.

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In this paper the algorithm of finding eigenvalues and eigenfunctions for the leaky modes in a three-layer planar dielectric waveguide is considered. The problem on the eigenmodes of open three-layer waveguides is formulated as the Sturm-Liouville problem with the corresponding boundary and asymptotic conditions. In the case of guided and radiation modes of open waveguides, the Sturm-Liouville problem is formulated for self-adjoint second-order operators on the axis and the corresponding eigenvalues are real quantities for dielectric media. The search for eigenvalues and eigenfunctions corresponding to the leaky modes involves a number of difficulties: the boundary conditions for the leaky modes are not self-adjoint, so that the eigenvalues can turn out to be complex quantities. The problem of finding eigenvalues and eigenfunctions will be associated with finding the complex roots of the nonlinear dispersion equation. In the present paper, an original scheme based on the method of finding the minimum of a function of several variables is used to find the eigenvalues. The paper describes the algorithm for searching for eigenvalues, the algorithm uses both symbolic transformations and numerical calculations. On the basis of the developed algorithm, the dispersion relation for the weakly flowing mode of a three-layer open waveguide was calculated in the Maple computer algebra system.

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9

He, Guang S., Chan F. Zhao, Chi-Kyun Park, Paras N. Prasad, and Ryszard Burzynski. "Dye film leaky waveguide laser." Optics Communications 111, no. 1-2 (September 1994): 82–85. http://dx.doi.org/10.1016/0030-4018(94)90143-0.

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10

Vukomanovic, Mladen, Jose-Luis Vazquez-Roy, Oscar Quevedo-Teruel, Eva Rajo-Iglesias, and Zvonimir Sipus. "Gap Waveguide Leaky-Wave Antenna." IEEE Transactions on Antennas and Propagation 64, no. 5 (May 2016): 2055–60. http://dx.doi.org/10.1109/tap.2016.2539376.

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11

Magnusson, Robert, and Mehrdad Shokooh-Saremi. "Properties of Nanostructured Resonant Leaky-Mode Photonic Devices." Advances in Science and Technology 55 (September 2008): 101–7. http://dx.doi.org/10.4028/www.scientific.net/ast.55.101.

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In this paper, we review the basic properties of resonant leaky mode elements implemented with periodic waveguide layers and consider their applicability in photonic devices and systems. Leaky waveguide modes can be exited when an incident light beam is coupled into the waveguide structure through an inscribed periodicity under phase-matching conditions. This results in generation of a guided-mode resonance field response in the spectrum. Device operation can be explained in terms of the photonic band structure and associated leaky-wave effects near the second stop band. Resonant devices such as bandpass/bandstop filters, polarizers, wideband reflectors, biosensors, tunable filters, and display pixels can be designed using this operational principle.

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12

Huo, Xingying, and Zheng Li. "Right/Left-Handed Leaky Rectangular Waveguide with Broadside Radiation Property." International Journal of Antennas and Propagation 2021 (January 21, 2021): 1–5. http://dx.doi.org/10.1155/2021/8309431.

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When a leaky rectangular waveguide is used to realize the coverage of radio wave in the small confined spaces, there will be a shadow region, which influences the coverage performance. In this paper, the traditional leaky rectangular waveguide is improved according to the principle of the equivalent circuit, by cutting interdigital slots in the upper wall and adding uniserial metal vias between the upper and lower walls of the rectangular waveguide. Thus, the right/left-handed transmission line property is introduced to the periodic leaky-waveguide (LWG), realizing the broadside radiation with relatively high gain (15.7 dBi), good cross polarization (−50 dB), and narrow half-power beamwidth (10.9°) at 6.97 GHz and providing a method for a uniform coverage of the radio wave in rooms without a shadow region.

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13

Park, Sang-Jin, Hoe-Woong Kim, and Young-Sang Joo. "Leaky Lamb Wave Radiation from a Waveguide Plate with Finite Width." Applied Sciences 10, no. 22 (November 16, 2020): 8104. http://dx.doi.org/10.3390/app10228104.

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In this paper, leaky Lamb wave radiation from a waveguide plate with finite width is investigated to gain a basic understanding of the radiation characteristics of the plate-type waveguide sensor. Although the leaky Lamb wave behavior has already been theoretically revealed, most studies have only dealt with two dimensional radiations of a single leaky Lamb wave mode in an infinitely wide plate, and the effect of the width modes (that are additionally formed by the lateral sides of the plate) on leaky Lamb wave radiation has not been fully addressed. This work aimed to explain the propagation behavior and characteristics of the Lamb waves induced by the existence of the width modes and to reveal their effects on leaky Lamb wave radiation for the performance improvement of the waveguide sensor. To investigate the effect of the width modes in a waveguide plate with finite width, propagation characteristics of the Lamb waves were analyzed by the semi-analytical finite element (SAFE) method. Then, the Lamb wave radiation was computationally modeled on the basis of the analyzed propagation characteristics and was also experimentally measured for comparison. From the modeled and measured results of the leaky radiation beam, it was found that the width modes could affect leaky Lamb wave radiation with the mode superposition and radiation characteristics were significantly changed depending on the wave phase of the superposed modes on the radiation surface.

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14

Cruz y Cruz, Sara, and Oscar Rosas-Ortiz. "Leaky Modes of Waveguides as a Classical Optics Analogy of Quantum Resonances." Advances in Mathematical Physics 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/281472.

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A classical optics waveguide structure is proposed to simulate resonances of short range one-dimensional potentials in quantum mechanics. The analogy is based on the well-known resemblance between the guided and radiation modes of a waveguide with the bound and scattering states of a quantum well. As resonances are scattering states that spend some time in the zone of influence of the scatterer, we associate them with the leaky modes of a waveguide, the latter characterized by suffering attenuation in the direction of propagation but increasing exponentially in the transverse directions. The resemblance is complete because resonances (leaky modes) can be interpreted as bound states (guided modes) with definite lifetime (longitudinal shift). As an immediate application we calculate the leaky modes (resonances) associated with a dielectric homogeneous slab (square well potential) and show that these modes are attenuated as they propagate.

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15

Hu, Jonathan, and Curtis R. Menyuk. "Understanding leaky modes: slab waveguide revisited." Advances in Optics and Photonics 1, no. 1 (January 29, 2009): 58. http://dx.doi.org/10.1364/aop.1.000058.

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16

Priye, V., and M. Tsutsumi. "Nonreciprocal behaviour of leaky gyrotropic waveguide." Electronics Letters 29, no. 1 (January 7, 1993): 104–5. http://dx.doi.org/10.1049/el:19930068.

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17

Georgiades, Evripides, Michael J. S. Lowe, and Richard V. Craster. "Leaky wave characterisation using spectral methods." Journal of the Acoustical Society of America 152, no. 3 (September 2022): 1487–97. http://dx.doi.org/10.1121/10.0013897.

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Leaky waves are an important class of waves, particularly for guiding waves along structures embedded within another medium; a mismatch in wavespeeds often leads to leakage of energy from the waveguide, or interface, into the medium, which consequently attenuates the guided wave. The accurate and efficient identification of theoretical solutions for leaky waves is a key requirement for the choices of modes and frequencies required for non-destructive evaluation inspection techniques. We choose a typical situation to study: an elastic waveguide with a fluid on either side. Historically, leaky waves are identified via root-finding methods that have issues with conditioning, or numerical methods that struggle with the exponential growth of solutions at infinity. By building upon a spectral collocation method, we show how it can be adjusted to find exponentially growing solutions, i.e., leaky waves, leading to an accurate, fast, and efficient identification of their dispersion properties. The key concept required is a mapping, in the fluid region, that allows for exponential growth of the physical solution at infinity, whilst the mapped numerical setting decays. We illustrate this by studying leaky Lamb waves in an elastic waveguide immersed between two different fluids and verify this using the commercially available software disperse.

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18

Stallein, M., B. Bandlow, and R. Schuhmann. "Using quasi-guided modes for modeling the transfer behavior of bent dielectric slab waveguides." Advances in Radio Science 8 (September 30, 2010): 19–26. http://dx.doi.org/10.5194/ars-8-19-2010.

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Abstract. The connection of two straight dielectric multimode slab waveguides by a circular bent waveguide is analyzed by means of quasi-guided modes. These modes correspond to the well known leaky modes, but own real eigenvalues, thus the mathematical description is simpler. Furthermore they are derived as approximate solutions of the exact theory. This work will first give a brief introduction to the basic theory, followed by a discussion of the properties of quasi-guided modes. After a validation by comparison with a numerical simulation using the Finite Integration Technique, results for the bending loss of multimode waveguides are presented.

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19

Qiu, Chencheng, Liu Liu, Botao Han, Jiachi Zhang, Zheng Li, and Tao Zhou. "Broadband Wireless Communication Systems for Vacuum Tube High-Speed Flying Train." Applied Sciences 10, no. 4 (February 18, 2020): 1379. http://dx.doi.org/10.3390/app10041379.

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A vactrain (or vacuum tube high-speed flying train) is considered as a novel proposed rail transportation approach in the ultra-high-speed scenario. The maglev train can run with low mechanical friction, low air resistance, and low noise mode at a speed exceeding 1000 km/h inside the vacuum tube regardless of weather conditions. Currently, there is no research on train-to-ground wireless communication system for vactrain. In this paper, we first summarize a list of the unique challenges and opportunities associated with the wireless communication for vactrain, then analyze the bandwidth and Quality of Service (QoS) requirements of vactrain’s train-to-ground communication services quantitatively. To address these challenges and utilize the unique opportunities, a leaky waveguide solution with simple architecture but excellent performance is proposed for wireless coverage for vactrains. The simulation of the leaky waveguide is conducted, and the results show the uniform phase distribution along the horizontal direction of the tube, but also the smooth field distribution at the point far away from the leaky waveguide, which can suppress Doppler frequency shift, indicating that the time-varying frequency-selective fading channel could be approximated as a stationary channel. Furthermore, the train-to-ground wireless access architectures based on leaky waveguide are studied and analyzed. Finally, the moving scheme is adopted based on centralized, cooperative, cloud Radio Access Network (C-RAN), so as to deal with the extremely frequent handoff issue.

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20

Felix Servin, Jesus Manuel, and Max Deffenbaugh. "Leaky waveguides in hydrocarbon reservoirs and their implications for oil banks detection." GEOPHYSICS 87, no. 2 (December 30, 2021): E63—E77. http://dx.doi.org/10.1190/geo2020-0788.1.

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The presence of naturally occurring subsurface waveguides for electromagnetic (EM) waves has been previously documented. In particular, the mining industry recognized that a coal seam bounded by layers of conductive rock acts as a leaky waveguide. Consequently, the attenuation constant and phase shift of EM signals propagating through the coal layer are modulated by the thickness of the coal and the EM properties of the three layers forming the leaky waveguide. The radio imaging method was developed based on this discovery to characterize coal deposits. Recent studies have determined that guided waves can provide useful information about the subsurface. Structures with similar dimensions and EM properties are found in oil fields in the form of layers of evaporite (e.g., anhydrite) bounded by hydrocarbon reservoirs. To the best of our knowledge, the feasibility of exploiting such structures to characterize the interwell region has not been investigated extensively. We have conducted a theoretical analysis and 3D numerical simulations in the time and frequency domains to demonstrate that layered structures in oil fields can act as leaky waveguides and efficiently guide EM waves. Our results suggest that such structures substantially enhance the propagation of megahertz EM signals. Among multiple parameters evaluated, the conductivity of the layers has the most significant effect on signal attenuation, and thus its range of propagation. We estimated that EM signals of approximately 10 MHz can propagate several hundreds of meters through a layer of anhydrite in the presence of conductive bounding reservoirs. The received signals are not only affected by the properties of the anhydrite layer, but also by the properties of the bounding reservoirs, conferring sensitivity to changes in reservoir saturation. We conclude that this approach could be further developed to infer fluid saturation and especially to identify the presence of oil banks in water-flooded hydrocarbon reservoirs.

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21

Fuscaldo, Walter, Dimitrios C. Zografopoulos, Francesca Imperato, Paolo Burghignoli, Romeo Beccherelli, and Alessandro Galli. "Analysis and Design of Tunable THz 1-D Leaky-Wave Antennas Based on Nematic Liquid Crystals." Applied Sciences 12, no. 22 (November 19, 2022): 11770. http://dx.doi.org/10.3390/app122211770.

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The tunable properties of nematic liquid crystals (NLC) are here exploited in a peculiar leaky waveguide with artificial magnetic conductors as the lateral walls, a bottom metal ground plane, and a homogenized metasurface on top to obtain dynamic beamsteering at a fixed terahertz frequency. The waveguide consists of an NLC cell sandwiched between two dielectric layers. The proposed antenna system works on its transverse-magnetic leaky mode and is capable of radiating a beam that scans either by frequency or by changing the bias voltage applied across the NLC cell. The design parameters are optimized through a rigorous modal analysis of the structure, and the radiation performance is validated through full-wave simulations. The results are promising for the realization of next-generation tunable terahertz leaky-wave antennas.

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22

Ayushi, Ashutosh Tripathi, Areeba Nafis, Saksham Omer, and Ruchi Agarwal. "Substrate Integrated Waveguide based Leaky Wave Antenna." Journal of Physics: Conference Series 1921 (May 2021): 012052. http://dx.doi.org/10.1088/1742-6596/1921/1/012052.

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23

Allilomes, Peter C., and George A. Kyriacou. "A Nonlinear Finite-Element Leaky-Waveguide Solver." IEEE Transactions on Microwave Theory and Techniques 55, no. 7 (July 2007): 1496–510. http://dx.doi.org/10.1109/tmtt.2007.900306.

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24

Whetten, F. L., and C. A. Balanis. "Meandering long slot leaky-wave waveguide-antennas." IEEE Transactions on Antennas and Propagation 39, no. 11 (1991): 1553–60. http://dx.doi.org/10.1109/8.102768.

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25

Bird, T. S. "Finite-element analysis of leaky waveguide antennas." Electronics Letters 22, no. 13 (1986): 697. http://dx.doi.org/10.1049/el:19860477.

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26

Zinov'ev, K. E., V. A. Sychugov, and B. A. Usievich. "Leaky-mode waveguide in layered dielectric gratings." Quantum Electronics 30, no. 1 (January 31, 2000): 69–72. http://dx.doi.org/10.1070/qe2000v030n01abeh001661.

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27

VALERA, J. D., J. S. AITCHISON, D. J. GOODWILL, A. C. WALKER, I. D. HENNING, and S. RITCHIE. "MODAL BISTABILITY IN A GaAlAs LEAKY WAVEGUIDE." Le Journal de Physique Colloques 49, no. C2 (June 1988): C2–307—C2–310. http://dx.doi.org/10.1051/jphyscol:1988272.

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28

Huo, Xingying, Junhong Wang, Dawei Li, Zhan Zhang, Meie Chen, and Zheng Li. "Leaky Rectangular Waveguide With Circular Polarization Property." IEEE Transactions on Antennas and Propagation 63, no. 11 (November 2015): 5098–101. http://dx.doi.org/10.1109/tap.2015.2473693.

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29

Uchiyama, Yasushi, Masanori Ozaki, and Katsumi Yoshino. "Leaky mode operation in FLC/waveguide modulator." Ferroelectrics 149, no. 1 (December 1993): 217–28. http://dx.doi.org/10.1080/00150199308217294.

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30

Kumar, A., V. Rastogi, and K. S. Chiang. "Leaky optical waveguide for high power applications." Applied Physics B 85, no. 1 (September 1, 2006): 11–16. http://dx.doi.org/10.1007/s00340-006-2425-5.

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31

Okamoto, Takayuki, and Ichirou Yamaguchi. "Absorption Measurement Using a Leaky Waveguide Mode." Optical Review 4, no. 3 (May 1997): 354–57. http://dx.doi.org/10.1007/s10043-997-0354-0.

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32

Ashok, Nandam, and Vipul Rastogi. "Dual-Core Leaky Waveguide-Based Filters for Erbium-Doped Waveguide Amplifier." Fiber and Integrated Optics 32, no. 4 (July 4, 2013): 242–50. http://dx.doi.org/10.1080/01468030.2013.799246.

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33

Rzhanov, A. G., and S. E. Grigas. "Numerical algorithm for waveguide and leaky modes determination in multilayer optical waveguides." Technical Physics 55, no. 11 (November 2010): 1614–18. http://dx.doi.org/10.1134/s1063784210110113.

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34

Prakash, Ved, Sunita Kumawat, and Priti Singh. "Design and Analysis of Full and Half Mode Substrate Integrated Waveguide Planar Leaky Wave Antenna with Continuous Beam Scanning in X-Ku Band." Frequenz 73, no. 5-6 (May 27, 2019): 171–78. http://dx.doi.org/10.1515/freq-2018-0212.

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AbstractIn this paper, substrate-integrated waveguide (SIW) and half mode substrate integrated waveguide (HM-SIW) periodic leaky wave antennas (LWAs) are presented for the antenna applications. The continuous beam scanning (CBS) is realized by optimizing the unit cell by matching its impedance to the characteristic impedance of the waveguide. This leaky wave antenna is capable of total 60 ° scanning from −38 ° to + 22 ° as the frequency changes from 10.17 GHz to 16.3 GHz with a maximum gain of 11 dBi. Moreover, for further miniaturization, HM-SIW technology is employed in the presented LWA. This LWA is also capable of CBS from −50 ° to + 26 ° in the frequency band of 10 GHz to 16.5 GHz with a maximum gain of 12 dBi. The final prototypes of the both these antenna are fabricated and measured results are in agreement with the simulated ones.

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35

Kelebekler, Ersoy. "An analysis of leaky hybrid modes depending on structural parameters in a circular dielectric rod." Frequenz 75, no. 9-10 (April 19, 2021): 377–87. http://dx.doi.org/10.1515/freq-2020-0189.

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Abstract Open dielectric waveguides are structures used to guide electromagnetic energy in integrated circuits above the cutoff or as leaky wave antennas propagating the energy transversely out of the waveguide in a narrow region below the cutoff. In this study, the related operating regions for the hybrid EH modes of a cylindrical dielectric rod were obtained analytically. Analyses of the leaky wave characteristics of the hybrid EH modes for various radii of the rod and various dielectric constant values were performed. The guided modes existing above the cutoff with a pure real propagation constant, and the leaky wave modes existing below the cutoff with a complex propagation constant, were obtained from the coefficient matrix of the characteristic equations system of the structure using the bisection method and Davidenko’s method, respectively. Additionally, the guided modes of the structure were obtained and designated in the light of previous studies in the literature. The results show that the frequency spectrum of the antenna mode region increases as the value of the dielectric constant and the radius of the dielectric rod decrease. In addition, a circular dielectric with a smaller radius and dielectric constant had a larger frequency spectrum in the leaky wave antenna applications.

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36

Zhang, Chong, Junhong Wang, Meie Chen, Zhan Zhang, and Zheng Li. "A New Kind of Circular Polarization Leaky-Wave Antenna Based on Substrate Integrated Waveguide." International Journal of Antennas and Propagation 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/397960.

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A new kind of circular polarization leaky-wave antenna with N-shaped slots cut in the upper side of substrate integrated waveguide (SIW) is investigated and presented. The radiation pattern and polarization axial ratio of the leaky-wave antenna are studied. The results show that the width of N-shaped slots has significant effect on the circular polarization property of the antenna. By properly choosing structural parameters, the SIW based leaky-wave antenna can realize circular polarization with excellent axial ratio in 8 GHz satellite band.

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37

Nečiūnas, Audrius, Martynas Patašius, and Rimantas Barauskas. "CALCULATING DISPERSION RELATIONS FOR WAVEGUIDE IMMERSED IN PERFECT FLUID." Mathematical Modelling and Analysis 23, no. 2 (April 18, 2018): 309–26. http://dx.doi.org/10.3846/mma.2018.019.

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Conventional ﬁnite element method (FEM) is capable of obtaining wave solutions, but large discretized structures at high frequency require high computational resources, the computational domain can be reduced by combining FEM with analytical assumption for guided wave. Semi Analytical Finite Element (SAFE) formulation for immersed waveguide in perfect ﬂuid is used for acquiring propagating wave modes as dynamic equilibrium states. Modes are solutions to eigenvalue problem and provide with important characteristic features of the guided waves – phase velocity, attenuation, wave structure, etc. The eﬀect of surrounding leaky medium is modeled via traction boundary condition, which is based on assumption of the continuity of stresses at solid-ﬂuid interface. The boundary condition causes wave attenuation due to energy leakage into outer medium. The derivation of the eigen-problem takes into account complex wavenumbers of leaky wave in ﬂuid and guided wave in a three-dimensional waveguide. Linearization procedure for solving nonlinear eigenvalue problem is used. Dispersion relations for immersed waveguide with Rayleigh damping are obtained. The limits of applications of Rayleigh damping and convergence analysis of immersed waveguide model are discussed.

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Uranus, Henri P., and B. M. A. Rahman. "Low-loss ARROW waveguide with rectangular hollow core and rectangular low-density polyethylene/air reflectors for terahertz waves." Journal of Nonlinear Optical Physics & Materials 27, no. 03 (September 2018): 1850029. http://dx.doi.org/10.1142/s0218863518500297.

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Designing low-loss waveguides for terahertz waves is challenging as most materials are very lossy in this frequency band. Most scientists simply consider transmitting the waves through low-loss air, which however also has its own difficulties as index-guiding is not possible. In this paper, we report on the design of low-loss waveguides for terahertz waves and associated results by using a finite element leaky mode solver. These results show that waveguides designed using ARROW (anti-resonant reflecting optical waveguide) approach yield a low combined absorption and leakage loss down to only 0.05[Formula: see text]dB/cm for the q-TE[Formula: see text] fundamental mode using realistic values of refractive index at 1 THz operating frequency. The structure employs rectangular hollow-core and low-density polyethylene/air anti-resonant reflecting bilayers, which can be easily fabricated. These results are compared with those of other structures, i.e., a photonic crystal fiber-like structures using the same materials with rectangular holes, which is shown to give a higher loss of 3[Formula: see text]dB/cm and a suspended air-core waveguide with TOPAS vein offering a loss of 1[Formula: see text]dB/cm.

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39

Kelebekler, Ersoy. "Investigation of the Leaky-Wave Characteristics of a Cylindrical Dielectric Rod Using the Coefficient Matrix of the System of Characteristic Equations and Davidenko’s Method." Journal of Electromagnetic Engineering and Science 21, no. 3 (July 31, 2021): 189–200. http://dx.doi.org/10.26866/jees.2021.3.r.26.

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An open dielectric waveguide includes both guided propagating modes within the waveguide and radiating and evanescent modes that propagate transversely outside the waveguide. In this study, the leaky-wave characteristics of a cylindrical dielectric rod are investigated using the coefficient matrix of the system of characteristic equations and Davidenko’s method. Using the coefficient matrix of the system of characteristic equations simplified the derivative(s) required to use Davidenko’s method. The results obtained for a 10-mm radius structure with a relative dielectric constant of 4 showed that a second antenna mode region existed for higher-order hybrid HE modes and lower-order transverse magnetic (TM) modes. However, it did not exist for transverse electric (TE) modes. Additionally, the hybrid HE modes had larger leaky-wave spectrum and antenna mode regions than both the TE and TM modes. This demonstrates that for antenna applications, hybrid HE modes supply a wider frequency spectrum.

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40

Parra, Jorge O., Brian J. Zook, Pei‐Cheng Xu, and Raymon L. Brown. "Transmission and detection of guided seismic waves in attenuating media." GEOPHYSICS 63, no. 4 (July 1998): 1190–99. http://dx.doi.org/10.1190/1.1444419.

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We can use guided seismic waves to map properties of reservoirs between wells, with the low‐velocity layers acting as waveguides. When guided waves are detected, they are an indication of the continuity of the bed examined. Guided waveforms are characterized by time‐frequency representations to study important physical properties of the beds acting as waveguides. We used full waveform seismic modeling in viscoelastic media to examine the required velocity contrasts and distances over which guided‐wave signals can be used. In one set of models, sandstones are the central waveguide lithology; in another set, shales. We applied these models, referred to here collectively as shaly sandstone waveguides, to a range of geological circumstances where either the sands or the shales represent the low‐velocity layers within a reservoir. To study the distances over which guided waves can be detected, we compared the amplitudes of the signals computed for the models, using a realistic source strength, to the signal levels determined from published borehole noise studies. In shaly sandstone waveguides, we find it is feasible to use particle velocity measurements to record guided waves above seismic noise levels in the frequency range of 60 to 800 Hz at well separations exceeding a distance of 800 m. However, pressure detectors such as hydrophones may only be useful up to distances of 400 m between wells. In addition to the issues of shaly sandstone waveguides and practical distances between wells, we present an application of guided waves using crosswell seismic data from the Gypsy test site in Oklahoma (a site originally established by British Petroleum). In this field example within a sandstone reservoir, we demonstrate the sensitivity of leaky mode amplitudes to source‐receiver location. Another telltale characteristic of continuity in the type of reservoir studied at the Gypsy test site, where there is a low shear velocity contrast between the host medium and the waveguide, is the head wave followed by the leaky mode.

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41

Sevastyanov, Anton L. "Investigation of adiabatic waveguide modes model for smoothly irregular integrated optical waveguides." Discrete and Continuous Models and Applied Computational Science 30, no. 2 (May 3, 2022): 149–59. http://dx.doi.org/10.22363/2658-4670-2022-30-2-149-159.

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The model of adiabatic waveguide modes (AWMs) in a smoothly irregular integrated optical waveguide is studied. The model explicitly takes into account the dependence on the rapidly varying transverse coordinate and on the slowly varying horizontal coordinates. Equations are formulated for the strengths of the AWM fields in the approximations of zero and first order of smallness. The contributions of the first order of smallness introduce depolarization and complex values characteristic of leaky modes into the expressions of the AWM electromagnetic fields. A stable method is proposed for calculating the vertical distribution of the electromagnetic field of guided modes in regular multilayer waveguides, including those with a variable number of layers. A stable method for solving a nonlinear equation in partial derivatives of the first order (dispersion equation) for the thickness profile of a smoothly irregular integrated optical waveguide in models of adiabatic waveguide modes of zero and first orders of smallness is described. Stable regularized methods for calculating the AWM field strengths depending on vertical and horizontal coordinates are described. Within the framework of the listed matrix models, the same methods and algorithms for the approximate solution of problems arising in these models are used. Verification of approximate solutions of models of adiabatic waveguide modes of the first and zero orders is proposed; we compare them with the results obtained by other authors in the study of more crude models.

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42

Alamrani, Nasser A., Gillian M. Greenway, Nicole Pamme, Nicholas J. Goddard, and Ruchi Gupta. "A feasibility study of a leaky waveguide aptasensor for thrombin." Analyst 144, no. 20 (2019): 6048–54. http://dx.doi.org/10.1039/c9an01421g.

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This proof-of-principle study demonstrates the feasibility of a leaky waveguide (LW) aptasensor, where aptamers were immobilised in a mesoporous chitosan waveguiding film for the detection of thrombin.

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Gupta, Ruchi, Anil K. Pal, and Nicholas J. Goddard. "Biosensing by Direct Observation of Leaky Waveguide Modes." Journal of Physics: Conference Series 1919, no. 1 (May 1, 2021): 012002. http://dx.doi.org/10.1088/1742-6596/1919/1/012002.

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44

Zhang, Tieyan, De He, Lu Liu, Qiqige Wulan, Jiachen Yu, Zhe Li, and Zhijun Liu. "Monolayer molecular sensing using infrared leaky waveguide mode." AIP Advances 11, no. 3 (March 1, 2021): 035305. http://dx.doi.org/10.1063/5.0039597.

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45

Hadley, G. Ronald. "Two-dimensional waveguide modeling of leaky-mode arrays." Optics Letters 14, no. 16 (August 15, 1989): 859. http://dx.doi.org/10.1364/ol.14.000859.

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46

Pogossian, S. P., J. Ben-Youssef, H. Le Gall, J. M. Desvignes, and A. Menelle. "New neutron magnetic low index leaky waveguide coupler." Journal of Applied Physics 81, no. 8 (April 15, 1997): 4281–83. http://dx.doi.org/10.1063/1.365552.

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47

Bird, T. S. "Erratum: Finite-element analysis of leaky waveguide antennas." Electronics Letters 22, no. 18 (1986): 967. http://dx.doi.org/10.1049/el:19860660.

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Malins, Chris, Peter R. Fielden, Nicholas J. Goddard, Thomas G. Harvey, and Philip Summersgill. "Embossed polymer leaky waveguide devices for spectroscopic analysis." Analyst 126, no. 8 (2001): 1293–97. http://dx.doi.org/10.1039/b103393j.

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49

Malherbe, J. A. G. "A leaky-wave antenna in nonradiative dielectric waveguide." IEEE Transactions on Antennas and Propagation 36, no. 9 (1988): 1231–35. http://dx.doi.org/10.1109/8.8601.

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Dawei Song and Ya Yan Lu. "Analyzing Leaky Waveguide Modes by Pseudospectral Modal Method." IEEE Photonics Technology Letters 27, no. 9 (May 1, 2015): 955–58. http://dx.doi.org/10.1109/lpt.2015.2403844.

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