Physical limitations on broadband scattering by heterogeneous obstacles

Abstract

In this paper, new physical limitations on the extinction cross section and broadband scattering are investigated. A measure of broadband scattering in terms of the integrated extinction is derived for a large class of scatterers based on the holomorphic properties of the forward scattering dyadic. Closedform expressions of the integrated extinction are given for the homogeneous ellipsoids, and theoretical bounds are discussed for arbitrary heterogeneous scatterers. Finally, the theoretical results are illustrated by numerical computations for a series of generic scatterers.

Minimum Q for Lossy and Lossless Electrically Small Dipole Antennas

“…Expressing the electric dipole moment p 1 in terms of the the realvalued, symmetric [34] electric polarizability dyadicᾱ e of a PEC volume V a in a uniform electric field E 01 = E 0 , namely…”

“…(The surface integrals at an infinite radius in the vector Green's first identity vanish because B e2 decays as 1/r 2 and thus B * e2 · ∇ × B e2 decays as 1/r 5 as r → ∞.) Expressing the electric dipole moment p 2 in terms of the realvalued, symmetric [34] electric polarizability dyadicᾱ m of a PMC volume V a in a uniform quasi-static electric field E 02 = −E 0 , namely…”

On the Relation Between Optimal Wideband Matching and Scattering of Spherical Waves

“…They have also been used recently to derive a series of new sum rules for the scattering of electromagnetic waves [3,25,26], with applications in antenna theory [11,29,30].…”

“…Integral identities based on the properties of Herglotz functions [4], or positive real (PR) functions [35], constitute the basis for deriving Fano's broadband matching bounds [8] and have been used recently to describe a series of new sum rules for the scattering of electromagnetic waves [3,4,25,26]. Hence, under the assumptions of linearity, continuity, time-translational invariance and passivity, sum rules can be derived from the analytic properties of the forward scattering dyadic, see e.g., [25,26], and have also applications in antenna theory, see e.g., [11,12,24,29,30].…”

“…Hence, under the assumptions of linearity, continuity, time-translational invariance and passivity, sum rules can be derived from the analytic properties of the forward scattering dyadic, see e.g., [25,26], and have also applications in antenna theory, see e.g., [11,12,24,29,30]. In [23], similar relations are used to determine the ultimate thickness to bandwidth ratio of radar absorbers.…”