Wideband electromagnetic cloaking systems

Patent metadata

Field	Value
Publication number	US-2017302000-A9
Application number	US-201514886838-A
Country	US
Kind code	A9
Filing date	Oct 19, 2015
Priority date	Aug 25, 2008
Publication date	Oct 19, 2017
Grant date	—

Abstract

Arrangement of resonators in an aperiodic configurations are described, which can be used for electromagnetic cloaking of objects. The overall assembly of resonators, as structures, do not all repeat periodically and at least some of the resonators are spaced such that their phase centers are separated by more than a wavelength. The arrangements can include resonators of several different sizes and/or geometries arranged so that each size or geometry corresponds to a moderate or high “Q” response that resonates within a specific frequency range, and that arrangement within that specific grouping of akin elements is periodic in the overall structure. The relative spacing and arrangement of groupings can be defined by self similarity and origin symmetry. Fractal based scatters are described. Further described are bondary condition layer structures that can activate and deactive cloaking/lensing structures.

First claim

What is claimed is:

1 . An electrical resonator system, comprising:
a plurality of concentric electrical resonator shells, each shell including a substrate having first and second surfaces and a close-packed arrangement of electrically conductive material formed on the first surface, wherein the closed-packed arrangement comprises a plurality of self-similar electrical resonator shapes and is configured to operate at a desired passband of electro-magnetic radiation; and wherein the close-packed arrangements of at least two antenna shells are different in size and/or shape.

2 . The system of claim 1 , wherein said passband is about 2:1.

3 . The system of claim 2 , wherein said passband is about 3:1.

4 . The system of claim 1 , wherein the electrical system is configured and arranged so that radiation incident on the system from a given direction has an intensity on a point-by-point basis such at each respective antipodal point, relative to an object placed at the center of the system, the radiation has the same or similar intensity.

5 . The system of claim 1 , wherein the antenna system is configured and arranged so that radiation incident on the system from a direction in cylindrical coordinates has the same or similar intensity at the antipodal point after having traversed the antenna system.

6 . The system of claim 1 , wherein the plurality of antenna shells comprises a first pair of shells having similar closed-packed arrangements for operation at a first passband, wherein the two shells are positioned within ⅛λ of one another.

7 . The system of claim 6 , wherein the plurality of antenna shells comprises a second pair of shells having similar closed-packed arrangements for operation at a s second frequency band, wherein the two shells are positioned within ⅛λ of one another.

8 . The system of claim 1 , wherein the plurality of antenna shells are hemispherical.

9 . The system of claim 1 , wherein the plurality of antenna shells are cylindrical.

10 . The system of claim 1 , wherein the plurality of antenna shells are spherical.

11 . The system of claim 9 , wherein each shell is configured and arranged to be opened and closed to allow placement of an object within the shell.

12 . The system of claim 1 , wherein resonator in the close-packed arrangement comprises a second order or higher fractal.

13 . The system of claim 12 , wherein said fractal is selected from the group consisting of a Koch fractal, a Minkowski fractal, a Cantor fractal, a torn square fractal, a Mandelbrot, a Caley tree fractal, a monkey's swing fractal, a Sierpinski gasket, and a Julia fractal.

14 . The system of claim 12 , wherein the fractal is selected from the group consisting of a contour set fractal, a Sierpinski triangle fractal, a Menger sponge fractal, a dragon curve fractal, a space-filling curve fractal, a Koch curve fractal, an lypanov fractal fractal, and a Kleinian group fractal.

15 . The system of claim 1 , wherein the plurality of concentric electrical resonator shells are configured and arranged for operation at K band, Ka band, or X-band.

16 . The system of claim 1 , wherein the resonator shapes of one shell are about 1 cm on a side.

17 . The system of claim 1 , wherein the resonator shapes of one shell are about 1.5 cm on a side.

18 . The system of claim 1 , wherein the system is operation over a bandwidth from about 500 MHz to about 1500 MHz.

19 . The system of claim 1 , further comprising a BCL defining an inner volume and configured and arranged to activate and deactivate the resonator system.

20 . A fractal based scatterer comprising:
a shell composed of flexible substrate in the shape of a band joined in a cylindrical shape having a conductive coating with fractal cutouts, wherein the scatterer produces a greater radar cross section for its physical size than would otherwise be produced by its physical size alone.

Assignees

• Fractal Antenna Systems Inc

Inventors

• Nathan Cohen
• Okoro Obinna
• Salkind Phillip

Classifications

• H01Q15/0093 Primary

  having a fractal shape · CPC title

• H01Q17/008

  with a particular shape (H01Q17/007 takes precedence) · CPC title

• H01Q15/06

  comprising plurality of wave-guiding channels of different length · CPC title

• H01Q15/02

  Refracting or diffracting devices, e.g. lens, prism · CPC title