Mobile communication base station antenna

1. A mobile communication base station antenna, comprising:

a plurality of array antenna blocks, each of the array antenna blocks comprising a plurality of antenna element pairs, each of the antenna element pairs comprising antenna elements that are disposed to be orthogonal to each other,

wherein tilt angles in a vertical plane of respective array antenna blocks are different from each other,

wherein the array antenna blocks are arranged along a same axis in a vertical direction in the vertical plane,

wherein said each of the array antenna blocks has same polarization characteristics,

wherein a Multiple Input Multiple Output (MIMO) communication is carried out by the array antenna blocks,

wherein the array antenna blocks are provided with a common grounding potential, and

wherein the array antenna blocks are connected via a conductive plate.

2. The mobile communication base station antenna according to claim 1 , wherein the tilt angles in the vertical plane of the respective array antenna blocks are determined such that a correlation coefficient between the respective array antenna blocks is 0.7 or less.

3. The mobile communication base station antenna according to claim 1 , wherein the tilt angles in the vertical plane of the respective array antenna blocks are arbitrarily set by mechanically changing a direction of each of the array antenna blocks.

4. The mobile communication base station antenna according to claim 1 , wherein the tilt angles in the vertical plane of the respective array antenna blocks are arbitrarily set by shifting a signal phase by a phase shifter.

5. The mobile communication base station antenna according to claim 4 , wherein the phase shifter comprises a fixed phase shifter in which a shift amount of the signal phase is fixed.

6. The mobile communication base station antenna according to claim 4 , wherein the phase shifter comprises a variable phase shifter in which a shift amount of the signal phase is freely determined.

7. The mobile communication base station antenna according to claim 1 , further comprising:

a first feeding port electrically connected to one of the antenna elements of said each of the antenna element pairs; and

a second feeding port electrically connected to another one of the antenna elements of said each of the antenna element pairs.

8. The mobile communication base station antenna according to claim 7 , wherein a combination of the one of the antenna elements and said another one of the antenna elements carries out the MIMO communication.

9. The mobile communication base station antenna according to claim 1 , wherein the polarization characteristics comprise a degree of polarization.

10. The mobile communication base station antenna according to claim 1 , wherein a tilt angle of one of the array antenna blocks located in an upper part of the mobile communication base station antenna is less than a tilt angle of another one of the array antenna blocks located in a lower part of the mobile communication base station antenna.

11. The mobile communication base station antenna according to claim 1 , wherein the plurality of array antenna blocks is arranged linearly.

12. The mobile communication base station antenna according to claim 1 , wherein the plurality of array antenna blocks is arranged in a line such that centers of the antenna element pairs of one of the array antenna blocks and centers of the antenna element pairs of another one of the array antenna blocks are located on the line.

13. A mobile communication base station antenna, comprising:

a plurality of array antenna blocks, each of the array antenna blocks comprising a plurality of antenna element pairs each of the antenna element pairs comprising antenna elements that are disposed to be orthogonal to each other,

wherein tilt angles in a vertical plane of respective array antenna blocks are different from each other,

wherein the array antenna blocks are arranged along a same axis in a vertical direction in the vertical plane,

wherein said each of the array antenna blocks has same polarization characteristics, and

wherein a Multiple Input Multiple Output (MIMO) communication is carried out by the array antenna blocks; and

a conductive plate that connects an upper part of the array antenna blocks to a lower part of the array antenna blocks.

14. The mobile communication base station antenna according to claim 13 , wherein the upper part of the array antenna blocks is connected to the lower part of the array antenna blocks via the conductive plate with a common ground potential.

15. The mobile communication base station antenna according to claim 13 , wherein tilt angles of the array antenna blocks located in the upper part of the array antenna blocks are less than tilt angles of the array antenna blocks located in the lower part of the array antenna blocks.