Antenna device
An antenna device includes a substrate having a ground conductor, an antenna conductor disposed approximately parallel with the ground conductor with an air layer or a dielectric layer, plural short-circuiting conductors that connect the antenna conductor to the ground conductor, and a feed conductor disposed in a vicinity of one of the plural short-circuiting conductors and that feeds the antenna conductor with power. When a wavelength of frequency used in the antenna device is represented by λ, an outer circumferential length of the slot is approximately 1λ to 2λ and a width of the slot is 0.005λ to 0.05λ, an interval between the plural short-circuiting conductors is shorter than or equal to λ/2, and a distance between the antenna conductor and the ground conductor is 0.005λ to 0.05λ.
1. An antenna device comprising:
a substrate having a ground conductor;
a flat-plate-shaped antenna conductor disposed approximately parallel with the ground conductor with an air layer or a dielectric layer interposed between the antenna conductor and the ground conductor, and the antenna conductor having a closed polygon-shaped slot which is bent at at least one position thereof;
plural short-circuiting conductors that connect the antenna conductor to the ground conductor; and
a feed conductor disposed in a vicinity of one of the plural short-circuiting conductors and that feeds the antenna conductor with power,
wherein when a wavelength of frequency used in the antenna device is represented by λ,
an outer circumferential length of the slot is approximately 1λ to 2λ and a width of the slot is 0.005λ to 0.05λ;
an interval between the plural short-circuiting conductors is shorter than or equal to λ/2; and
a distance between the antenna conductor and the ground conductor is 0.005λ to 0.05λ.
2. The antenna device according to claim 1 , wherein the antenna conductor is configured by a plate-like member having an approximately rectangular external shape and has extension portions which extend from a shorter side or a longer side of the plate-like member and are bent approximately perpendicularly to a plane having the slot to form bent portions; and
wherein the short-circuiting conductors are formed by the bent portions of the antenna conductor.
3. The antenna device according to claim 1 , wherein the slot has a meandering shape which is bent at plural positions.
4. The antenna device according to claim 1 , wherein the substrate is a printed circuit board and the ground conductor is configured by a ground pattern; and
wherein the plural short-circuiting conductors are connected to the ground pattern of the ground conductor.
5. The antenna device according to claim 1 , further comprising:
a circuit component mounted on the substrate,
wherein the circuit component and the antenna conductor are arranged on the substrate.
6. The antenna device according to claim 1 , wherein the antenna conductor is configured by a plate-like member having an approximately rectangular external shape, lengths of shorter sides and longer sides of the antenna conductor are λ/8 to λ/2, a length of the slot in the longer-side direction of the antenna conductor is shorter than or equal to λ/2.
7. The antenna device according to claim 1 , wherein the antenna conductor has plural slots an outer circumferential length of each of which is approximately 1λ to 2λ.