US 7,911,407 B1 · Method for designing artificial surface impedance structures characterized by an impedance tensor with complex components

Abstract

A method for designing artificial impedance surfaces is disclosed. The method involves matching impedance component values required for a given far-field radiation pattern (determined, for example, by holographic means) with measured or simulated impedance component values for the units of a lattice of conductive structures used to create an artificial impedance surface, where the units of the lattice have varied geometry. For example, a unit could be a square conductive structure with a slice (removed or missing material) through it. The measured or simulated impedance components are determined by measuring wavevector values for test surfaces in three or more directions over any number of test surfaces, where each unit of a given test surface has the same geometric shape and proportions as all of the other units of that test surface, but each test surface has some form of variation in the unit geometry from the other test surfaces. These test measurements create a table of geometry vs. impedance components that are used to design the artificial impedance structure. Since polarization can be controlled, the structure can be an artificial impedance surface characterized by a tensor impedance having complex components.

Claims15

Dependent claims

A method for creating an artificial impedance surface characterized by an impedance tensor, comprising:

selecting a desired far-field pattern for a surface;
determining design impedance values as a function of location on the surface that would produce the desired far-field pattern;
selecting a patterning shape for the surface, the patterning shape having at least one geometric characteristic;
and
measuring sample tensor impedance component values for a plurality of test surfaces that have test patterning shapes that have varied measurements for the at least one geometric characteristic;
for each location on the surface,
(i) determining what values of the at least one geometric characteristic would give impedance values that most closely approximate the design impedance values for that location and
(ii) patterning the surface to include a unit cell with the patterning shape modified to have said at least one geometric characteristic would give impedance values that most closely approximate the design impedance values for that location.

5 more elements

A method for creating an artificial impedance surface characterized by an impedance tensor, comprising:

selecting a lattice design for the artificial impedance surface having a plurality of unit frames;
selecting, for the plurality unit frames, a surface patterning shape having at least one geometric characteristic that can be varied among the unit frames;
selecting a desired far-field pattern for the artificial impedance surface;
determining design impedance component values at each unit frame of the artificial impedance surface that would give the artificial impedance surface the desired far-field pattern;
determining each of the at least one geometric characteristic as a function of sample impedance component values;
for a given unit frame on the artificial impedance surface, use the at least one geometric characteristic as a function of the sample impedance component values and the design impedance component values to determine the values of the at least one geometric characteristic for said given unit frame that approximates the design impedance component values for said given unit frame;
and
patterning the artificial impedance surface with the surface patterning shape, varying the at least one geometric characteristic for each unit frame of the artificial impedance surface to substantially provide the desired far-field pattern.

5 more elements

Dependencies are inferred from the claim text.

Method for designing artificial surface impedance structures characterized by an impedance tensor with complex components

Life of this patent

Method for designing artificial surface impedance structures characterized by an impedance tensor with complex components

Life of this patent

Abstract

Claims15