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International Journal of Antennas and Propagation
Volume 2012 (2012), Article ID 187123, 9 pages
http://dx.doi.org/10.1155/2012/187123
Research Article

Can 𝜆 / 4 Radiators Be Really Isotropic?

1Department of Communication Engineering, Holon Academic Institute of Technology, 52 Golomb Street, Holon 58102, Israel
2AFEKA Tel Aviv Academic College of Engineering, 38 Mivza Kadesh, Tel Aviv 69107, Israel

Received 5 October 2011; Accepted 2 January 2012

Academic Editor: Dau-Chyrh Chang

Copyright © 2012 H. Matzner and E. Levine. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In search for isotropic radiators with reasonable quality Factor (Q), bandwidth, and efficiency, one looks for practical radiators with a typical resonant length of 𝜆 / 4 . We present here a Green's function analysis in Fourier of a 𝜆 / 4 microstrip element and a far-field integral method in configuration (real) space of single and dual U-shaped 𝜆 / 4 elements. Both solutions analytically prove that the power radiation patterns are isotropic in nature (while the thickness and the width tend to zero), although the polarizations are not symmetrical in all cuts. It is also shown that the power isotropic U-shaped radiator, for which the surface current density is infinite, can be replaced by another finite-size radiator, having finite-surface current density, such that its far-field is exactly the same as the far-field of the U-shaped isotropic radiator.