Proceedings Article•
Analysis of global eigenmodes in an oversized rectangular waveguide with a hard surface on one broad wall for planar slot array antenna applications
23 Mar 2009-pp 41-44
TL;DR: In this paper, the dispersion equation of a rectangular waveguide with one broad hard wall formed by longitudinal corrugations with grooves filled with dielectric is derived on the basis of using the asymptotic boundary conditions for corrugated surfaces.
Abstract: The problem of determining the eigenmodes of a rectangular waveguide with one broad hard wall formed by longitudinal corrugations with grooves filled with dielectric is considered. The dispersion equation is derived on the basis of using the asymptotic boundary conditions for corrugated surfaces. It is shown analytically that if the groove depth is equal to the value 0.25λ/(e−1)½ corresponding to the hard wall condition, the TE eigenmode spectrum of the waveguide comprises an infinite set of degenerated quasi-TEM modes with different transverse propagation constants and identical longitudinal propagation constants equal to the wavenumber k. Such solutions are important for understanding the local waves appearing along ridges in such waveguides, that has inspired to the invention of new so-called gap waveguides.
Citations
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Proceedings Article•
23 Mar 2009TL;DR: In this article, the basic ideas of how local waveguides and transmission lines can be designed to propagate along desired paths in the air gap between two metal surfaces are presented, related to the performance of artificial magnetic conductors, EBG surfaces and soft and hard surfaces.
Abstract: This paper presents the basic ideas of how local waveguides and transmission lines can be designed to propagate along desired paths in the air gap between two metal surfaces. The principle of operation is related to the performance of artificial magnetic conductors, EBG surfaces and soft and hard surfaces. Three different major types of gap waveguides are described: ridge gap waveguides, microstrip gap lines and groove gap waveguides. Different realizations of the cut-off structures suppressing normal parallel plate modes are described, as well as expected applications, and possible problem areas preferably seen as research challenges.
233 citations
01 Jan 1996
TL;DR: In this article, the unidirectional current screen was used as an asymptotic strip boundary condition (ASBC) for analysis of field problems containing metal strip grids.
Abstract: We discuss the unidirectional current screen as an asymptotic strip boundary condition (ASBC) for analysis of field problems containing metal strip grids, and we introduce a related asymptotic corrugation boundary condition (ACBC) for analysis of corrugated surfaces. The boundary conditions are asymptotic in the sense that the exact boundary conditions approach the asymptotic ones when the strip and corrugation periods approach zero. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14: 99–101, 1997.
69 citations
10 Nov 2009
TL;DR: The ridge gap waveguide as discussed by the authors is a waveguide appearing in the air gap between two parallel metal plates, where one of the plates has a metal texture, and confined local waves follow ridges in the texture whereas they are prohibited from propagating in other directions by metal pins.
Abstract: The paper presents a new waveguide appearing in the air gap between two parallel metal plates. One of the plates has a metal texture, and confined local waves follow ridges in the texture whereas they are prohibited from propagating in other directions by metal pins in the texture. The pins (or bed of nails) provide a high impedance surface that creates a stop band when used together with a metal surface, i.e. a parallel plate cut-off. The principle performance of the ridge gap waveguide is explained by numerical simulations of the dispersion diagram, both to show the parallel plate cut-off generated by the pin surface, but also to see the quasi-TEM wave propagating along the ridge. The performance is validated by numerical simulations and experimentally of a ridge gap waveguide with two 90 deg bends, including transitions to coaxial connectors. The ridge gap waveguide has a large potential for use up to THz because it can be realized without conducting joints between metal parts, and it lends itself to co-design and integration with active components.
13 citations
24 Jun 2011
TL;DR: In this article, the authors present a set of soluciones for antenas planas de barrido of high ganancia and bajo coste a frecuencias elevadas, e.g., the banda de microondas and the bandas demilim etricas.
Abstract: Inter es de la investigaci on: En los ultimos a~nos hemos asistidoa la aparici on de aplicaciones comerciales a frecuencias elevadas,como son la parte alta de la banda de microondas y las bandas demilim etricas y submilim etricas, y se espera un incremento en lospr oximos a~nos. Esta creciente demanda exige un r apido desarrollode tecnolog a de bajo coste con buenas prestaciones a estas frecuencias,donde las tecnolog as m as comunes, como son la tecnolog amicrostrip y las gu as de onda, presentan algunas de ciencias. Enconcreto, las soluciones existentes para antenas planas de barridode alta ganancia a estas frecuencias sufren los inconvenientes dedichas tecnolog as y dan lugar a productos con un coste demasiadoalto para su producci on masiva.Objetivos: El objetivo principal de la presente tesis doctoral consisteen estudiar la viabilidad de una nueva propuesta que mejorelas soluciones existentes hasta la fecha en lo referente a antenasplanas de barrido de alta ganancia y bajo coste a frecuencias elevadas.Este objetivo global ha desembocado en otro objetivo centralde esta tesis que consiste en la investigaci on de nuevas gu ascuasi-TEM m as apropiadas que las tecnolog as actuales para la realizaci on de circuitos y componentes en estas bandas de frecuencia.Estas soluciones guiadas hacen uso de super cies peri odicas o arti -ciales con la nalidad de con nar y dirigir los campos en el interiorde estas gu as.Metodolog a: El trabajo desarrollado sigue una secuencia l ogicade tareas espec cas encaminadas a la consecuci on del objetivo principalde esta tesis. En el cap tulo 2 se presenta la soluci on guiadapropuesta y se muestra su funcionamiento num erica y experimentalmente.El dise~no optimizado de antenas de alta ganancia basadasen agrupaciones de ranuras en gu a exige el desarrollo de c odigospropios e cientes. La implementaci on y validaci on de este c odigo sepresenta en el cap tulo 3, donde se propone un nuevo m etodo parael an alisis de super cies corrugadas, y en el cap tulo 4, donde seextiende este c odigo para el an alisis de agrupaciones de ranuras engu a. El proceso de dise~no y optimizaci on de una agrupaci on bidimensionalse describe en el cap tulo 5, donde se expone tambi enuna validaci on experimental preliminar. Por otra parte, la soluci onguiada propuesta ha inspirado la aparici on de una tecnolog a guiadacon mayor ancho de banda y m as vers atil para la realizaci on de circuitosy componentes a frecuencias elevadas. El cap tulo 6 presentalas contribuciones realizadas al estudio de esta tecnolog a y a suaplicaci on en el dise~no de circuitos.Resultados: Se ha demostrado num erica y experimentalmente quelas dos estructuras guiadas estudiadas aqu , una ideada como soportede una agrupaci on de ranuras, y la otra especialmente interesantepara la realizaci on de circuitos y componentes, presentanunas caracter sticas particulares que les con eren un gran potencialpara su aplicaci on en antenas y circuitos a frecuencias elevadas. Elestudio de viabilidad culmina con el dise~no de una agrupaci on deranuras bidimensional en la gu a propuesta. Para este dise~no se haempleado un c odigo propio e ciente basado en un m etodo nuevopara el an alisis de super cies corrugadas, el cual constituye una delas aportaciones principales de este trabajo. La aplicaci on de lasegunda estructura guiada en la realizaci on de circuitos se ha demostradomediante el dise~no, fabricaci on y medida de circuitos demicroondas.
12 citations
Cites background from "Analysis of global eigenmodes in an..."
...Certainly these waves are the result of a linear combination of eigenmodes and extend also to the whole waveguide cross-section, but they are negligible for most part of it [127]....
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01 Jan 2011
TL;DR: In this paper, the authors describe a new type of metamaterial-based quasi-TEM waveguiding device, which is based on the principle that combining two parallel plates, one being a perfect electric conductor and the other a perfect magnetic conductor, provides a stop band area between them as long as the separation between plates is less than a quarter wavelength.
Abstract: This review paper describes a new type of metamaterial-based quasi-TEM waveguiding device. The transmission line is based on the principle that combining two parallel plates, one being a perfect electric conductor and the other a perfect magnetic conductor, provides a stop band area between them as long as the separation between plates is less than a quarter wavelength. In that scenario, metallic inclusions such as strips, ridges or grooves open a propagation path in the gap between the inclusion and the metallic conductor and at the same time fields remain confined without resorting to vertical walls. The paper explains this concept in detail; it describes its advantages and shows several application examples and experimental demonstrations.
10 citations
References
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TL;DR: The ridge gap waveguide as mentioned in this paper is a metamaterial-based waveguide that can be realized in a narrow gap between two parallel metal plates by using a texture or multilayer structure on one of the surfaces.
Abstract: This letter presents a new metamaterial-based waveguide technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and sub- millimeter waves. The latter is due to the fact that there are no mechanical joints across which electric currents must float. The gap waveguides have lower losses than microstrip lines, and they are completely shielded by metal so no additional packaging is needed, in contrast to the severe packaging problems associated with microstrip circuits. The gap waveguides are realized in a narrow gap between two parallel metal plates by using a texture or multilayer structure on one of the surfaces. The waves follow metal ridges in the textured surface. All wave propagation in other directions is prohibited (in cutoff) by realizing a high surface impedance (ideally a perfect magnetic conductor) in the textured surface at both sides of all ridges. Thereby, cavity resonances do not appear either within the band of operation. The present letter introduces the gap waveguide and presents some initial simulated results.
738 citations
"Analysis of global eigenmodes in an..." refers background in this paper
...The example of such a mode can be a local quasi-TEM mode obtained in [7] by using a vertical post as source, and the new gap waveguides introduced in [8]....
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...The detection of these local waves have resulted in the invention of more general local gap waveguides that are formed between two parallel metal plates when one of them is textured to provide a high surface impedance except for metal ridges along which quasi-TEM waves can propagate [8]....
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TL;DR: In this paper, the concept of soft and hard surfaces is treated in detail, considering different geometries, and it is shown that both the hard and soft boundaries have the advantage of a polarizationindependent reflection coefficient for geometrical optics ray fields, so that a circularly polarized wave is circularly polarization in the same sense after reflection.
Abstract: A transversely corrugated surface as used in corrugated horn antennas represents a soft boundary. A hard boundary is made by using longitudinal corrugations filled with dielectric material. The concept of soft and hard surfaces is treated in detail, considering different geometries. It is shown that both the hard and soft boundaries have the advantage of a polarization-independent reflection coefficient for geometrical optics ray fields, so that a circularly polarized wave is circularly polarized in the same sense after reflection. The hard boundary can be used to obtain strong radiation fields along a surface for any polarization, whereas the soft boundary makes the fields radiated along the surface zero. >
677 citations
"Analysis of global eigenmodes in an..." refers background in this paper
...The lower waveguide wall is loaded with longitudinal corrugations, the grooves of which are filled with dielectric to form the well known hard surface structure [2], [3]....
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TL;DR: The widely used transversely corrugated surfaces and other alternative surfaces having the same anisotropic surface impedance deserve a common name as discussed by the authors, and it is proposed to call them soft surfaces by analogy with the soft surfaces in acoustics.
Abstract: The widely used transversely corrugated surfaces and other alternative surfaces having the same anisotropic surface impedance deserve a common name. Here it is proposed to call them soft surfaces by analogy with the soft surfaces in acoustics. In the same way artificially hard surfaces are defined. Cylindrical hard waveguides of any cross-sectional shape can support TEM waves.
349 citations
Journal Article•
TL;DR: In this article, the authors discuss and demonstrate the relation between electromagnetic bandgap surfaces (EBG) used to realize artificial magnetic conductors and the so-called soft and hard surfaces in electromagnetics, with respect to their STOP and GO characteristics for surface waves.
Abstract: We discuss and demonstrate by measurements and computations the relation between electromagnetic bandgap surfaces (EBG) used to realize artificial magnetic conductors and the so-called soft and hard surfaces in electromagnetics, with respect to their STOP and GO characteristics for surface waves. We show how the main characteristics of such surfaces can be modeled by using ideal surfaces representing perfect magnetic conductors (PMC) and PEC/PMC strip grids. Unfortunately, commercial codes do not allow such modeling for general shapes of the surfaces.
134 citations
01 Oct 1997
TL;DR: In this paper, the spectral-domain Green's functions for different realisations of planar soft and hard surfaces are developed by using the asymptotic boundary conditions and the spectral domain approach.
Abstract: The Green's functions for different realisations of planar soft and hard surfaces are developed by using the asymptotic boundary conditions and the spectral-domain approach. The geometries considered are the ideal perfect electric conductor/perfect magnetic conductor (PEC/PMC) strip surface, the strip-loaded grounded dielectric slab and the corrugated surface. In all cases the strips and corrugations are straight. The asymptotic boundary conditions are valid in the limiting sense, when the period of the strips or corrugations approaches zero. The Green's functions developed have poles corresponding to surface waves. These are of three types: an ordinary surface wave in the grounded dielectric slab propagating radially out from the source; a strip wave propagating along the strips of the strip-loaded dielectric slab and also along the strips of the PEC/PMC strip surface; and surface waves occurring due to the corrugated surface. Fulfilment of both the soft and hard boundary conditions is discussed in both the near- and far-field regions. The strip wave of the strip-loaded dielectric slab prevents the boundary conditions in the near-field from being fulfilled, and is thus undesired. The other two surface waves are needed to realise the hard boundary condition.
76 citations
"Analysis of global eigenmodes in an..." refers background in this paper
...The TE nature of these new waves make them related to the local TE surface waves appearing in open longitudinally corrugated surfaces detected first in [15]....
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