Circularly polarized scalar impedance artificial impedance surface antenna
AssigneeHRL Laboratories, LLC
InventorDaniel J. Gregoire
Life of this patent
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Abstract
A circularly polarized artificial impedance surface antenna (AISA) includes an impedance modulated substrate having a modulated scalar impedance to a surface wave traversing a top surface of the substrate, wherein the impedance modulation has a plurality of intertwined lines of constant impedance, and wherein each line of constant impedance follows a spiral elliptical path.
Claims28
A circularly polarized artificial impedance surface antenna (AISA) comprising:
- an impedance modulated substrate having a modulated scalar impedance to a surface wave traversing a top surface of the substrate;
- wherein the impedance modulated substrate has a plurality of intertwined lines of constant impedance;
- and
- wherein each line of constant impedance follows a spiral elliptical path.
A method of fabricating a circularly polarized artificial impedance surface antenna (AISA) comprising:
- forming an impedance modulated substrate having a modulated scalar impedance to a surface wave traversing a top surface of the substrate;
- wherein the impedance modulated substrate has a plurality of intertwined lines of constant impedance;
- and
- wherein each line of constant impedance follows a spiral elliptical path.
A circularly polarized artificial impedance surface antenna (AISA) comprising:
- an impedance modulated substrate having a modulated scalar impedance to a surface wave traversing a top surface of the substrate;
- wherein the modulated scalar impedance pattern is
- Z
-
- (
- x
- ,
- y
- )
- =
- X
- +
- M
-
- (
- sin
-
-
- γ
-
-
- cos
-
-
- ϕ
- cos
-
-
- θ
- 0
- ±
- cos
-
-
- γ
-
-
- sin
-
-
- ϕ
- )
- ;
- where X is the mean impedance;
- where M is the modulation amplitude;
- where θ0 is the elevation angle of maximal gain with respect to a normal to the AISA;
- where γ≡k0(n0ρ−x sin θ0);
- ko is a radiation's free-space wavenumber at a design frequency;
- no is a surface wave's refractive index averaged over the scalar impedance pattern;
- and ρ=√{square root over (x2+y2)};
- where
- tan
-
-
- ϕ
- ≡
- y
- x
- ;
- where the ± sign corresponds to the AISA operating in a right hand circularly polarized (RHCP) or left hand circularly polarized (LHCP) modes, respectively;
- and
- where X and M vary with ρ, the distance from the surface-wave source.
A method of fabricating a circularly polarized artificial impedance surface antenna (AISA) comprising:
- forming an impedance modulated substrate having a modulated scalar impedance to a surface wave traversing a top surface of the substrate;
- wherein the modulated scalar impedance pattern is
- Z
-
- (
- x
- ,
- y
- )
- =
- X
- +
- M
-
- (
- sin
-
-
- γ
-
-
- cos
-
-
- ϕ
- cos
-
-
- θ
- 0
- ±
- cos
-
-
- γ
-
-
- sin
-
-
- ϕ
- )
- ;
- where X is the mean impedance;
- where M is the modulation amplitude;
- where θ0 is the elevation angle of maximal gain with respect to a normal to the AISA;
- where γ≡k0(n0ρ−x sin θ0);
- ko is a radiation's free-space wavenumber at a design frequency;
- no is a surface wave's refractive index averaged over the scalar impedance pattern;
- and ρ=√{square root over (x2+y2)};
- where
- tan
-
-
- ϕ
- ≡
- y
- x
- ;
- where the ± sign corresponds to the AISA operating in a right hand circularly polarized (RHCP) or left hand circularly polarized (LHCP) modes, respectively;
- and
- where X and M vary with ρ, the distance from the surface-wave source.
Dependencies are inferred from the claim text.