Departmental Papers (ESE)


Pendry in his paper, “Negative refraction makes a perfect lens” (Phys. Rev. Lett., vol. 85, no. 18, pp. 3966–3969, 2000) put forward an idea for a lens made of a lossless metamaterial slab with n = -1, that may provide focusing with resolution beyond the conventional limit. In his analysis, the evanescent wave inside such a lossless double-negative (DNG) slab is “growing,” and thus it “compensates” the decaying exponential outside of it, providing the subwavelength lensing properties of this system. Here, we examine this debated issue of “growing exponential” from an equivalent circuit viewpoint by analyzing a set of distributed-circuit elements representing evanescent wave interaction with a lossless slab of DNG medium. Our analysis shows that, under certain conditions, the current in series elements and the voltage at the element nodes may attain the dominant increasing due to the suitable resonance of the lossless circuit, providing an alternative physical explanation for “growing exponential” in Pendry’s lens and similar subwavelength imaging systems.

Document Type

Journal Article

Date of this Version

January 2006


NOTE: At the time of publication, author Andrea Alù was affiliated with the University of Roma Tre. As of September 2006, she is a staff member in the Department of Electrical and Systems Engineering at the University of Pennsylvania. Copyright 2006 IEEE. Reprinted from IEEE Transactions on Antennas and Propagation, Volume 54, Issue 1, January 2006, pages 268-272.

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Double-negative (DNG) metamaterials, left-handed (LH) metamaterials, subwavelength resolution.



Date Posted: 14 April 2006

This document has been peer reviewed.