dc.contributor.author |
Margetis, D |
en |
dc.contributor.author |
Fikioris, G |
en |
dc.date.accessioned |
2014-03-01T01:50:33Z |
|
dc.date.available |
2014-03-01T01:50:33Z |
|
dc.date.issued |
2000 |
en |
dc.identifier.issn |
0022-2488 |
en |
dc.identifier.uri |
https://dspace.lib.ntua.gr/xmlui/handle/123456789/26048 |
|
dc.subject.classification |
Physics, Mathematical |
en |
dc.title |
Two-dimensional, highly directive currents on large circular loops |
en |
heal.type |
journalArticle |
en |
heal.language |
English |
en |
heal.publicationDate |
2000 |
en |
heal.abstract |
Properties of idealized, two-dimensional current distributions on circular loops are investigated analytically via the solution of a constrained optimization problem. The directivity in the far field is maximized under a fixed C = N/T, where N is the integral of the square of the current magnitude and T is the total radiated power. C enters the ensuing Fourier series for the current implicitly through a Lagrange multiplier alpha. For non-negative alpha and large electrical radius ka, the directivity and the current are evaluated approximately via combined use of the Poisson summation formula and the Mellin transform technique. As a result, a geometrical-ray representation for the current is derived for the case of directivities that are slightly larger than that of the uniform distribution. The analysis indicates certain advantages of large radiating structures for moderate values of the constraint C. In the limit C --> infinity of Oseen's "Einstein needle radiation," an asymptotic formula for the directivity is obtained. Possible extensions of these results to classes of smooth convex loops are briefly discussed. (C) 2000 American Institute of Physics. [S0022-2488(00)04109-8]. |
en |
heal.publisher |
AMER INST PHYSICS |
en |
heal.journalName |
JOURNAL OF MATHEMATICAL PHYSICS |
en |
dc.identifier.isi |
ISI:000088944400019 |
en |
dc.identifier.volume |
41 |
en |
dc.identifier.issue |
9 |
en |
dc.identifier.spage |
6130 |
en |
dc.identifier.epage |
6172 |
en |