Electronic apparatus capable of wirelessly communicating with external device mounted thereon, and external device

1. An electronic apparatus capable of communicating with an external device mounted thereon, the electronic apparatus comprising:

an apparatus engagement unit into which an external engagement unit of the external device is to be mounted; and

a plurality of apparatus wireless communicators located in the apparatus engagement unit so as to face a plurality of external wireless communicators located in the external engagement unit mounted into the apparatus engagement unit, respectively,

wherein antennas given by the respective apparatus wireless communicators are arranged in the apparatus engagement unit such that radiation characteristics of all of the antennas are at least not parallel.

2. The electronic apparatus according to claim 1 , wherein

the apparatus engagement unit comprises a metallic shoe plate that is engageable with the external engagement unit slidably mounted into the apparatus engagement unit, while surrounding the external engagement unit in three directions other than a sliding direction in which the external engagement unit slides, and

a distance between the apparatus wireless communicators and the external wireless communicators facing each other in a state in which the external engagement unit has been slidably mounted into the apparatus engagement unit is shorter than at least a distance between the apparatus wireless communicators and the metallic shoe plate.

3. The electronic apparatus according to claim 2 , wherein

the metallic shoe plate comprises a pair of engagement portions located so as to sandwich the external engagement unit of the external device from right and left sides, and a connection portion that connects the pair of engagement portions together,

the pair of engagement portions and the connection portion are engageable with the external engagement unit of the external device while surrounding the external engagement unit in the three directions other than the sliding direction so that the external engagement unit can be slidably mounted into between the pair of engagement portions toward the connection portion through a slide opening which is formed on a side of the metallic shoe plate where the pair of engagement portions are not connected by the connection portion,

the plurality of apparatus wireless communicators includes a first apparatus wireless communicator and a second apparatus wireless communicator which are located at a distance from each other in the sliding direction of the external engagement unit and are arranged in the metallic shoe plate in this order from a side of the slide opening,

the first apparatus wireless communicator located closest to the slide opening has a radiation characteristic toward the slide opening, and

the second wireless communicator located second closest to the slide opening after the first apparatus wireless communicator has a radiation characteristic perpendicular to the radiation characteristic of the first apparatus wireless communicator.

4. The electronic apparatus according to claim 1 , further comprising a cover member that is in sliding contact with the external device when the external engagement unit of the external device is slidably mounted into the apparatus engagement unit,

wherein the plurality of apparatus wireless communicators is covered with the cover member.

5. The electronic apparatus according to claim 1 , wherein directions in radiation characteristics of the apparatus wireless communicators are the directions of the maximum radiation in the directivities of antennas given by the respective apparatus wireless communicators.

6. The electronic apparatus according to claim 1 , wherein the electronic apparatus is an image pickup apparatus.

7. An external device capable of communicating with an electronic apparatus while being mounted on the electronic apparatus, the external device comprising:

an external engagement unit capable of being slidably mounted into an apparatus engagement unit of the electronic apparatus; and

a plurality of external wireless communicators located in the external engagement unit so as to face a plurality of apparatus wireless communicators located in the apparatus engagement unit of the electronic apparatus, respectively,

wherein antennas given by the respective apparatus wireless communicators are arranged in the external engagement unit such that radiation characteristics of all of the antennas are at least not parallel.

8. The external device according to claim 7 , wherein

the external engagement unit is engageable with a metallic shoe plate of the apparatus engagement unit, while being surrounded by the metallic shoe plate in three directions other than a direction in which the external device slidably mounted onto the electronic apparatus slides, and

a distance between the external wireless communicators and the apparatus wireless communicators facing each other in a state in which the external engagement unit has been slidably mounted into the apparatus engagement unit is shorter than at least a distance between the external wireless communicators and the metallic shoe plate of the electronic apparatus in the state in which the external engagement unit of the external device has been slidably mounted into the apparatus engagement unit.

9. The external device according to claim 8 , wherein

the plurality of external wireless communicators includes a first external wireless communicator and a second external wireless communicator which are located at a distance from each other in a direction in which the external engagement unit slidably mounted into the apparatus engagement unit slides and are arranged in this order from a side of a slide opening of the metallic shoe plate of the electronic apparatus,

the first external wireless communicator located closest to the slide opening has a radiation characteristic toward the slide opening; and

the second external wireless communicator located second closest to the slide opening after the first external wireless communicator has a radiation characteristic perpendicular to the radiation characteristic of the first external wireless communicator.

10. The external device according to claim 7 , wherein the plurality of external wireless communicators located in the external engagement unit is movable upward and downward in a direction in which the plurality of external wireless communicators comes into contact with and is separated from the electronic apparatus onto which the external engagement unit is slidably mounted.

11. The external device according to claim 10 , wherein

the plurality of external wireless communicators being movable upward and downward,

lies at a retracted position away from the electronic apparatus when the external engagement unit is to be slidably mounted onto the electronic apparatus, and

in a state in which the external engagement unit has been slidably mounted onto the electronic apparatus, moves down to become close to the electronic apparatus.

12. The external device according to claim 10 , wherein

the plurality of external wireless communicators being movable upward and downward, moves down from a retracted position away from the electronic apparatus to become close to the electronic apparatus in response to

an operation that causes the external engagement unit of the external device to be slidably mounted onto the electronic apparatus,

an operation that restricts a position at which the external engagement unit is mounted on the electronic apparatus, or

an operation of an operation member that is provided in the external device or the electronic apparatus.

13. The external device according to claim 7 , wherein the external device comprises a storage device that stores data for the electronic apparatus.