MOBILE RADIO DEVICE

1 . A mobile radio device comprising:

a substrate including a ground plane;

a casing for accommodating the substrate; and

an antenna including a feed element that is connected to a feeding point, the ground plane being a reference of ground for the feeding point, and a radiating element that functions, upon power being fed by establishing electromagnetic field coupling with the feed element, as a radiation conductor,

wherein the casing includes a conductor that is electrically and physically connected to the ground plane.

2 . The mobile radio device according to claim 1 , wherein the conductor is electrically and physically connected to the ground plane through a fixing member for fixing the substrate to the casing.

3 . The mobile radio device according to claim 1 , wherein, when an electrical length for inducing a principal mode of a resonance of the feed element is Le37, an electrical length for inducing a principal mode of a resonance of the radiating element is Le31, and a wavelength on the feed element or on the radiating element at a resonance frequency of the principal mode of the radiating element is λ, Le37 is less than or equal to (⅜)·λ, and

wherein, when the principal mode of the resonance of the radiating element is a dipole mode, Le31 is greater than or equal to (⅜)·λ and less than or equal to (⅝)·λ, and when the principal mode of the resonance of the radiating element is a loop mode, Le31 is greater than or equal to (⅞)·λ and less than or equal to ( 9/8)·λ.

4 . The mobile radio device according to claim 1 , wherein, when a wavelength at a resonance frequency of a principal mode of the radiating element in vacuum is λ 0 , a shortest distance between the feed element and the radiating element is less than or equal to 0.2×λ 0 .

5 . The mobile radio device according to claim 1 , wherein the radiating element includes a feeding part for receiving power from the feed element, and

wherein the feeding part is positioned at a portion of the radiating element other than a part with a lowest impedance in a resonance frequency of a principal mode of the radiating element.

6 . The mobile radio device according to claim 1 , wherein the radiating element includes a feeding part for receiving power from the feed element, and

wherein the feeding part is located at a part that is separated, by a distance that is greater than or equal to ⅛ of an entire length of the radiating element, from a portion of the radiating element with a lowest impedance at a resonance frequency of a principal mode.

7 . The mobile radio device according to claim 1 , wherein a distance with which the feed element and the radiating element are extended in parallel, while separated by a shortest distance, is less than or equal to ⅜ of a length of the radiating element.

8 . The mobile radio device according to claim 1 , wherein the radiating element includes a feeding part to which power is fed, upon establishing electromagnetic field coupling with the feed element, and

wherein, when a wavelength at a resonance frequency of a principal mode of the radiating element in vacuum is λ 0 , a shortest distance between the feeding part and the ground plane is greater than or equal to 0.034λ 0 and less than or equal to 0.21λ 0 .

9 . The mobile radio device according to claim 1 , further comprising:

a cover glass that entirely covers an image display surface of a display,

wherein the radiating element is installed in the cover glass.

10 . The mobile radio device according to claim 1 , wherein the radiating element is installed at a margin portion of the casing, wherein the conductor is not formed at the margin portion.

11 . The mobile radio device according to claim 1 , wherein a feeder circuit is installed on another substrate that is different from the substrate.