Antenna device

1. An antenna device comprising:

a substrate;

a metal chassis disposed adjacent a rear surface of the substrate;

a plurality of patch antenna elements formed in an array on at least a front surface of the substrate;

feeding lines formed on the front surface of the substrate and through which electricity is fed to the plurality of patch antenna elements; and

a ground conductor formed on the rear surface of the substrate in a portion opposite the feeding lines, wherein the substrate has a rectangular shape,

wherein the plurality of patch antenna elements are formed in a middle portion of the substrate in a short side direction of the substrate and arranged in a long side direction of the substrate, and

wherein the feeding lines are disposed in two side portions of the substrate in the short side direction of the substrate so as to extend in the long side direction of the substrate, the feeding lines branching such that the electricity is fed to the plurality of patch antenna elements,

wherein the ground conductor includes ground patterns formed on the two side portions of the substrate in the short side direction so as to be spaced apart from each other.

2. The antenna device according to claim 1 , wherein the substrate is disposed such that the ground patterns formed so as to be spaced apart from each other are in contact with the metal chassis so as to be electrically connected to each other via the metal chassis.

3. The antenna device according to claim 1 , wherein portions of each feeding line are formed on the rear surface of the substrate at positions near the plurality of patch antenna elements, each portion of the feeding line formed on the rear surface of the substrate and a corresponding one of the feeding lines formed on the front surface of the substrate are electrically connected to each other through a via hole, and each portion of the feeding line formed on the rear surface of the substrate and a corresponding one of the patch antenna elements are electrically connected to each other through a via hole.

4. The antenna device according to claim 1 , wherein the metal chassis is formed by a bending operation so as to have a recess in a portion opposite the middle portion of the substrate in the short side direction of the substrate, the middle portion being one in which the plurality of patch antenna elements are formed, the recess being open in a direction away from the substrate.

5. An antenna device comprising:

a substrate;

a metal chassis disposed adjacent a rear surface of the substrate;

a plurality of patch antenna elements formed in an array on at least a front surface of the substrate;

feeding lines formed on the front surface of the substrate and through which electricity is fed to the plurality of patch antenna elements; and

a ground conductor formed on the rear surface of the substrate in a portion opposite the feeding lines, wherein the substrate has a rectangular shape,

wherein the plurality of patch antenna elements are formed in a middle portion of the substrate in a short side direction of the substrate and arranged in a long side direction of the substrate, and

wherein the feeding lines are disposed in two side portions of the substrate in the short side direction of the substrate so as to extend in the long side direction of the substrate, the feeding lines branching such that the electricity is fed to the plurality of patch antenna elements,

wherein the ground conductor includes a ground pattern formed on the entirety of the rear surface of the substrate, and

wherein pattern-free portions in which the ground patterns are not formed are formed on the rear surface of the substrate in portions opposite the plurality of patch antenna elements.

6. The antenna device according to claim 5 , wherein each pattern-free portion vertically extends away from a corresponding one of the patch antenna elements and upper and lower portions of the pattern-free portion vertically extending away from the patch antenna element have different lengths.