The Theory of Chirowaveguides

Recently a new type of guided-wave structure, named chirowaveguide was suggested by the authors. The chirowaveguides consist of cylindrical waveguides filled with homogeneous isotropic chiral materials. Due to the electromagnetic chirality of the material inside the waveguide, several important features area associated with this type of guided-wave structure. In this paper, the theory of chirowaveguides is discussed and their salient features are analyzed. It is show that the Helmhotz equations for the longitudinal components of electric and magnetic fields in chirowaveguides are always coupled and consequently, in these waveguides individual transverse electric (TE), transverse magnetic (TM), or transverse electromagnetic (TEM) modes cannot be supported. As an illustrative example, the parallel-plate chirowaveguide is analyzed in detail and the corresponding dispersion relations, cut-off frequencies, propagating and evanescent modes are obtained. In the dispersion (Brillouin) diagram for a chirowaveguide, three regions are identified: the fast-fast-wave region, the fast-slow-wave region and the slow-slow-wave region. For each of these regions the electromagnetic field components in a parallel-plat chirowaveguide are analyzed and the electric field components are plotted. Potential applications of chirowaveguides in integrated optical devices, communication systems, and printed circuit antennas are mentioned

Coupled-mode theory for chirowaveguide

In this paper, electromagnetic wave propagation and mode coupling in a chirowaveguide are treated using the coupled-mode theory. A chirowaveguide, as defined in our previous work, is a conventional cylindrical waveguide filled with homogeneous chiral materials. A set of coupled linear differential equations is derived for various mode amplitudes in the waveguide. We then show that, in any single chirowaveguide, owing to the handed properties of chiral materials filling the waveguide, energy coupling occurs from one mode to the other. We also demonstrate that in a parallel-plate chirowaveguide a TE mode can be completely converted into a TM mode and vice versa as they propagate in the guide. Thus a chirowaveguide can indeed be used as a mode converter. Selected results are compared with those reported in the literature. Applications of such mode coupling in the design of novel microwave, millimeterwave, and optical devices and components are mentioned

Periodic Chiral Structures

The electromagnetic properties of a structure that is both chiral and periodic are investigated using coupled-mode equations. The chirality is characterized by the constitutive relations D = εE + iXicB and H = iXicE+B/µ, where Xic is the chiral admittance. The periodicity is described by a sinusoidal perturbation of the permittivity, permeability and chiral admittance. The coupled-mode equations are derived from physical considerations. The coupled-mode equations are used to examine bandgap structure and reflected and transmitted fields. Chirality is observed predominantly in transmission while periodicity is present in both reflection and transmission

Chirality in guided-wave structures and printed-circuit antennas: Theory and applications

Electromagnetic chirality, which describes the role of chirality or handeness in electromagnetics, is exhibited in chiral materials. Isotropic chiral materials can be described electromagnetically by the constitutive relations D = \varepsilon\sb{\rm c} E + i\xi\sb{\rm c} B and H = i\xi\sb{\rm c} E + B/\mu\sb{\rm c} where \varepsilon\sb{\rm c}, \mu\sb{\rm c}, and \xi\sb{\rm c} are the permittivity, permeability and chirality admittance of the medium, respectively. Here, we introduce the concept of chirality into guided-wave structures and printed-circuit antenna technology. We develop the theory of chirowaveguides which consist of conventional waveguides containing chiral materials. We apply this theory to the cases of perfectly conducting parallel-plate, circular, and rectangular chirowaveguides. Novel features such as mode bifurcation and hybrid modes are discussed. We then extend our analyses to waveguides with open boundaries and investigate the electromagnetic properties of grounded and ungrounded chiral slabs. In particular, we determine the modes of electromagnetic waves in a grounded chiral slab (surface-wave and radiation modes), and introduce sources to model chirostrip antennas which consist of microstrip antennas with their substrates and/or superstrates replaced by chiral layers. We investigate the canonical cases of a line and a dipole antennas on top of grounded chiral slabs and show that, under certain circumstances, the surface wave power for a line source can be reduced and the radiation efficiency increased. We also present the radiation properties of line and dipole chirostrip arrays and study the effect of chirality on the sidelobe levels of these arrays. We then consider the more realistic finite-length chirostrip antenna and investigate its radiation properties such as current distribution, radiation patterns, input impedance, bandwidth, efficiency and mutual coupling between two such antennas. We find that a compromise has to be made between a wider bandwidth and a lower efficiency as compared with the nonchiral case. We also show that, due to chirality, the main beam of the radiation pattern is rotated around the axis normal to the slab. We finally show that, when chiral materials are used for the substrates, the mutual coupling between two finite-length chirostrip antennas is generally reduced. A whole host of applications of chiral materials in guided-wave structures and microstrip antennas are also addressed

Osteochondroma of the Scapula with Accessory Nerve (XI) Compression

Osteochondroma is the most common benign bone tumor and is characterized as a cartilage-capped bony stalk. This lesion usually develops from the growth plate of long bones. Most osteochondromas are asymptomatic. Neurovascular compressions or cosmetic issues can occur in specific locations. Malignant transformation is extremely rare, and MRI can help evaluate these lesions. Symptomatic mass and malignancy features are the main surgical indications. Uncommonly, an osteochondroma can develop from flat bones. We present the case of a 25-year-old patient with a right scapula osteochondroma causing an accessory nerve compression. The mass was surgically removed, and the diagnosis was confirmed. The patient fully recovered at the latest 3-year follow-up visit

81. 23 juin 1836. Ordonnance portant règlement pour les écoles de filles

Louis-Philippe , Pelet de la Lozère Privat Joseph Claramond. 81. 23 juin 1836. Ordonnance portant règlement pour les écoles de filles. In: L'enseignement du Français à l'école primaire – Textes officiels. Tome 1 : 1791-1879. Paris : Institut national de recherche pédagogique, 1992. p. 125. (Bibliothèque de l'Histoire de l'Education, 5

81. 23 juin 1836. Ordonnance portant règlement pour les écoles de filles

Louis-Philippe , Pelet de la Lozère Privat Joseph Claramond. 81. 23 juin 1836. Ordonnance portant règlement pour les écoles de filles. In: L'enseignement du Français à l'école primaire – Textes officiels. Tome 1 : 1791-1879. Paris : Institut national de recherche pédagogique, 1992. p. 125. (Bibliothèque de l'Histoire de l'Education, 5

22. 23 juin 1836, Ordonnance du Roi portant règlement pour les écoles de filles (extrait)

Louis-Philippe , Pelet de la Lozère Privat Joseph Claramond. 22. 23 juin 1836, Ordonnance du Roi portant règlement pour les écoles de filles (extrait). In: L'enseignement de l'histoire à l'école primaire de la Révolution à nos jours, textes officiels, Tome I : 1793-1914. Paris : Institut national de recherche pédagogique, 2007. pp. 117-118. (Bibliothèque de l'Histoire de l'Education, 22

22. 23 juin 1836, Ordonnance du Roi portant règlement pour les écoles de filles (extrait)

Louis-Philippe , Pelet de la Lozère Privat Joseph Claramond. 22. 23 juin 1836, Ordonnance du Roi portant règlement pour les écoles de filles (extrait). In: L'enseignement de l'histoire à l'école primaire de la Révolution à nos jours, textes officiels, Tome I : 1793-1914. Paris : Institut national de recherche pédagogique, 2007. pp. 117-118. (Bibliothèque de l'Histoire de l'Education, 22

Discussion concernant le décret sur les formalités de mise en accusation d'un représentant du peuple et demande de renvoyer aux comités une proposition de Pelet, lors de la séance du 8 brumaire an III (29 octobre 1794)

Merlin (de Douai), Pérès de Lagesse Emmanuel, Pelet Jean. Discussion concernant le décret sur les formalités de mise en accusation d'un représentant du peuple et demande de renvoyer aux comités une proposition de Pelet, lors de la séance du 8 brumaire an III (29 octobre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome C - Du 3 au 18 brumaire an III (24 octobre au 8 novembre 1794) Paris : CNRS éditions, 2000. p. 183