# US 9,882,286 B1 · Cylindrical antenna using near zero index metamaterial

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- Number: US 9,882,286 B1
- Document ID: US9882286B1
- Status: Granted
- Kind: B1
- Application number: 13/556,567
- Filed: 2012-07-24
- Granted: 2018-01-30
- Earliest claimed: 2012-07-24
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: David A. Tonn
- Inventors: David A. Tonn
- Web page: https://patentgrep.com/patent/US9882286B1

## CPC

- H01Q 19/06: using refracting or diffracting devices, e.g. lens {(radome H01Q1/42)}
- H01Q 15/0086: {said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials}
- H01Q 15/08: formed of solid dielectric material
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)

## Abstract

A cylindrical antenna includes: a hollow cylinder having a height, an inner radius b, an axis, a cylindrical surface, and two ends; a ground plane on one end of the cylinder; an antenna wire extending from a center of the cylinder at one end on a ground plane along the axis and ending below the height of the cylinder; and a layer of near zero index (NZI) metamaterial surrounding and adjacent to the cylindrical surface.

## Claims

### Claim 1

A cylindrical antenna comprising:
a hollow cylinder having a height, an inner radius b, an axis, a cylindrical surface, and two ends;
a ground plane joined to one end of the cylinder;
an antenna wire extending from a center of the cylinder proceeding from the end of the cylinder that is joined to the ground plane through an aperture in the ground plane along the axis and ending below the height of the cylinder; and
a layer of near zero index (NZI) metamaterial surrounding and adjacent to the cylindrical surface.

### Claim 2 (depends on 1)

The cylindrical antenna of claim 1 wherein the NZI metamaterial is isotropic and obeys the relationship:
ɛ
r
⁡
(
ω
)
=
n
2
⁡
(
ω
)
=
1
-
ω
p
2
ω
⁡
(
ω
-
j
⁢
⁢
γ
)
where ωp is an effective plasma frequency, γ is a damping coefficient, n is a refractive index, ω is the angular frequency of operation, j is the square root of −1, and ∈r is a relative dielectric constant of the metamaterial.

### Claim 3 (depends on 2)

The cylindrical antenna of claim 2 wherein the effective plasma frequency ωp is within 25% of an operational frequency of the antenna.

### Claim 4 (depends on 3)

The cylindrical antenna of claim 3 wherein an inner diameter of the hollow cylinder supports a resonant cavity mode.

### Claim 5 (depends on 3)

The cylindrical antenna of claim 3 wherein the radius b obeys the relationship:
Y
1
⁡
(
k
r
⁢
b
)
≈
2
π
⁢
J
1
⁡
(
k
r
⁢
b
)
⁢
ln
⁡
(
η
⁢
⁢
k
r
⁢
b
)
where Y1 and J1 are first order Bessel functions of first and second kind, respectively, kr is a resonant wave number being 2/π times the operational frequency, b is the inner radius, and n is a geometry factor involving a ratio of b and an outer radius of the antenna.

### Claim 6 (depends on 1)

The cylindrical antenna of claim 1 wherein the NZI metamaterial is anisotropic.

### Claim 7 (depends on 1)

The cylindrical antenna of claim 1 wherein the cylinder is filled with air or low dielectric foam.

### Claim 8 (depends on 1)

The cylindrical antenna of claim 1 comprising one of a monopole, a dipole and a bicone antenna.