Multiantenna unit and communication apparatus

1. A multiantenna unit comprising:

a first antenna element and a second antenna element; and

a non-grounded passive element arranged between said first antenna element and said second antenna element, wherein

said passive element includes a first portion arranged on a first surface of a substrate and an extensional portion, connected to said first portion, extending in a direction intersecting with said first surface,

said passive element further includes a second portion, and

said extensional portion includes a first extensional portion connected to said first portion and a second extensional portion connected to said second portion.

2. The multiantenna unit according to claim 1 , wherein

said first portion includes a first faced portion arranged to face said first antenna element, and

said second portion includes a second faced portion arranged to face said second antenna element.

3. The multiantenna unit according to claim 1 , wherein

said passive element further includes a third portion connected to said extensional portion and arranged on a second surface of said substrate at a prescribed interval from said first surface where said first portion is arranged.

4. The multiantenna unit according to claim 3 , further comprising said substrate, on which said first antenna element, said second antenna element and said passive element are arranged, having at least said first surface, wherein

said extensional portion is arranged to extend in said direction intersecting with said first surface of said substrate.

5. The multiantenna unit according to claim 4 , wherein

said substrate has a front surface consisting of said first surface and a back surface consisting of said second surface opposite to said front surface,

said first portion and said second portion are arranged on said front surface of said substrate, and

said third portion is arranged on said back surface of said substrate.

6. The multiantenna unit according to claim 3 , wherein

said first portion and said second portion arranged on said first surface are arranged to overlap with said third portion arranged on said second surface in plan view.

7. The multiantenna unit according to claim 2 , wherein

said first faced portion and said second faced portion of said passive element are arranged at distances allowing electromagnetic field coupling from said first antenna element and said second antenna element respectively.

8. The multiantenna unit according to claim 1 , wherein

said passive element has an electrical length of substantially half the wavelength of electric waves output from said first antenna element and said second antenna element.

9. The multiantenna unit according to claim 1 , further comprising:

a first feeding point feeding high-frequency power to said first antenna element and a second feeding point feeding high-frequency power to said second antenna element,

a first matching circuit arranged between said first antenna element and said first feeding point for attaining impedance matching at a prescribed frequency of said high-frequency power, and

a second matching circuit arranged between said second antenna element and said second feeding point for attaining impedance matching at a prescribed frequency of said high-frequency power.

10. The multiantenna unit according to claim 1 , wherein

said passive element is provided in a shape bent or curved on a plurality of positions in the same plane.

11. The multiantenna unit according to claim 1 , wherein

said first antenna element and said second antenna element include monopole antennas.

12. A communication apparatus comprising a multiantenna unit, wherein

said multiantenna unit includes:

a first antenna element and a second antenna element, and

a non-grounded passive element arranged between said first antenna element and said second antenna element, and

said passive element includes a first portion arranged on a first surface and an extensional portion, connected to said first portion, extending in a direction intersecting with said first surface,

said passive element further includes a second portion, and

said extensional portion includes a first extensional portion connected to said first portion and a second extensional portion connected to said second portion.