Electromagnetic eigenfrequencies in concentric spheroidal-spherical cavities

Kokkorakis, GC; Roumeliotis, JA

dc.contributor.author	Kokkorakis, GC	en
dc.contributor.author	Roumeliotis, JA	en
dc.date.accessioned	2014-03-01T01:17:48Z
dc.date.available	2014-03-01T01:17:48Z
dc.date.issued	2002	en
dc.identifier.issn	0920-5071	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14671
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0036219321&partnerID=40&md5=5cdbac12b338ee0191eb3bb4c199f309	en
dc.subject.classification	Engineering, Electrical & Electronic	en
dc.subject.classification	Physics, Applied	en
dc.subject.classification	Physics, Mathematical	en
dc.subject.other	Bessel functions	en
dc.subject.other	Boundary conditions	en
dc.subject.other	Eigenvalues and eigenfunctions	en
dc.subject.other	Electric field effects	en
dc.subject.other	Perturbation techniques	en
dc.subject.other	Electromagnetic eigenfrequencies	en
dc.subject.other	Electromagnetic field effects	en
dc.title	Electromagnetic eigenfrequencies in concentric spheroidal-spherical cavities	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2002	en
heal.abstract	The electromagnetic eigenfrequencies f(nsm) in perfectly conducting concentric spheroidal-spherical cavities are determined analytically. Two types of cavities are examined, one with spheroidal outer and spherical inner boundary and inversely for the other. The problem is solved by two different methods. In the first, the electromagnetic field is expressed in terms of both spherical and spheroidal eigenvectors, connected with one another by well-known expansion formulas. In the second, a shape perturbation method, the field is expressed in terms of spherical eigenvectors only, while the equation of the spheroidal boundary is given in spherical coordinates. The analytical determination of the eigenfrequencies is possible for small values of h = d/(2R(2)), (h much less than 1), with d the interfocal distance of the spheroidal boundary and 2R2 the length of its rotation axis. In this case exact, closed-form expressions are obtained for the expansion coefficients g(nsm)((2)) and g(nsm)((4)) in the resulting relation f(nsm)(h) = f(ns)(0) [1 + h(2) g(nsm)((2)) + h(4) g(nsm) ((4)) + O(h(6))]. Analogous expressions are obtained by using the parameter v = 1 - (R-2/R-2')(2) (for \v\ much less than 1), with 2R(2)' the length of the other axis of the spheroidal boundary. Numerical results are given for various values of the parameters.	en
heal.publisher	VSP BV	en
heal.journalName	Journal of Electromagnetic Waves and Applications	en
dc.identifier.isi	ISI:000174926100011	en
dc.identifier.volume	16	en
dc.identifier.issue	2	en
dc.identifier.spage	253	en
dc.identifier.epage	280	en