Antenna, array antenna, sector antenna, and dipole antenna

1. An antenna comprising:

a reflective member including a flat part;

a first antenna element disposed on the flat part of the reflective member, the first antenna element being configured to transmit and receive radio waves of a first polarization;

a second antenna element disposed on the flat part of the reflective member, one end of the second antenna element being located close to one end of the first antenna element, the second antenna element being configured to transmit and receive radio waves of a second polarization different from the first polarization;

a conductive member disposed close to the one ends of the first antenna element and the second antenna element and near a point of intersection where the first antenna element and the second antenna element meet when extended;

a third antenna element disposed on the flat part of the reflective member, the third antenna element being configured to transmit and receive radio waves of the first polarization;

a fourth antenna element disposed on the flat part of the reflective member, one end of the fourth antenna element being located close to one end of the third antenna element, the fourth antenna element being configured to transmit and receive radio waves of the second polarization; and

another conductive member disposed close to the one ends of the third antenna element and the fourth antenna element and near a point of intersection where the third antenna element and the fourth antenna element meet when extended,

wherein the other end of the fourth antenna element is located close to the other end of the first antenna element, and the other end of the third antenna element is located close to the other end of the second antenna element,

wherein each of the first antenna element, the second antenna element, the third antenna element and the fourth antenna element is a dipole antenna comprising:

two radiation parts;

a support part extending to the flat part of the reflective member, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion;

wherein each of the conductive member and the another conductive member is a rod-like or plate-like member rising from the flat part of the reflective member, and

each of the conductive member and the another conductive member is directly connected to the reflective member at one position.

2. An antenna comprising:

a reflective member including a flat part;

a first antenna element disposed on the flat part of the reflective member, the first antenna element being configured to transmit and receive radio waves of a first polarization;

a second antenna element disposed on the flat part of the reflective member, one end of the second antenna element being located close to one end of the first antenna element, the second antenna element being configured to transmit and receive radio waves of a second polarization different from the first polarization; and

a conductive member disposed close to the one ends of the first antenna element and the second antenna element and near a point of intersection where the first antenna element and the second antenna element meet when extended, wherein

each of the first antenna element and the second antenna element is a dipole antenna comprising:

two radiation parts;

a support part extending to the flat part of the reflective member, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion;

wherein the conductive member is a rod-like or plate-like member rising from the flat part of the reflective member, and

the conductive member is directly connected to the reflective member at one point.

3. An array antenna comprising:

a reflective member including a flat part;

a plurality of first antennas arranged on the flat part of the reflective member, each of the plurality of first antennas including a first antenna element, a second antenna element, a third antenna element, a fourth antenna element, a first conductive member, and a second conductive member, the first antenna element being configured to transmit and receive radio waves of a first polarization in a first frequency band, the second antenna element being configured to transmit and receive radio waves of a second polarization in the first frequency band different from the first polarization in the first frequency band, one end of the second antenna element being located close to one end of the first antenna element, the third antenna element being configured to transmit and receive radio waves of the first polarization in the first frequency band, the fourth antenna element being configured to transmit and receive radio waves of the second polarization in the first frequency band, one end of the fourth antenna element being located close to one end of the third antenna element, the first conductive member being disposed close to the one ends of the first antenna element and the second antenna element and near a point of intersection where the first antenna element and the second antenna element meet when extended, the second conductive member being disposed close to the one ends of the third antenna element and the fourth antenna element and near a point of intersection where the third antenna element and the fourth antenna element meet when extended, the other end of the first antenna element being located close to the other end of the fourth antenna element, the other end of the second antenna element being located close to the other end of the third antenna element; and

a plurality of second antennas arranged on the flat part of the reflective member along an array of the plurality of first antennas, each of the plurality of second antennas being configured to transmit and receive radio waves in a second frequency band higher than the first frequency band, wherein

each of the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element included in each of the plurality of first antennas is a dipole antenna comprising:

two radiation parts;

a support part extending to the flat part of the reflective member, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion.

4. The array antenna according to claim 3 , wherein an array of the plurality of second antennas is arranged on the flat part of the reflective member such that the array of the plurality of second antennas overlaps the array of the plurality of first antennas.

5. The array antenna according to claim 3 , wherein an interval in the array of the plurality of first antennas is three times an interval in the array of the plurality of second antennas.

6. The array antenna according to claim 3 , wherein two of the plurality of second antennas are disposed in an area surrounded by the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element of each of the plurality of first antennas.

7. The array antenna according to claim 3 , wherein radio waves transmitted and received by the plurality of first antennas include radio waves of +45 degree polarization and −45 degree polarization relative to an array of the plurality of first antennas.

8. An array antenna comprising:

a reflective member including a flat part;

a plurality of first antennas arranged on the flat part of the reflective member, each of the plurality of first antennas including a first antenna element, a second antenna element, a third antenna element, a fourth antenna element, and a conductive member, the first antenna element being configured to transmit and receive radio waves of first polarization in a first frequency band, the second antenna element being configured to transmit and receive radio waves of second polarization in the first frequency band different from the first polarization, one end of the second antenna element being located close to one end of the first antenna element, the third antenna element being configured to transmit and receive radio waves of the first polarization in the first frequency band, one end of the third antenna element being located close to the one end of the first antenna element, the fourth antenna element being configured to transmit and receive radio waves of the second polarization in the first frequency band, one end of the fourth antenna element being located close to the one end of the first antenna element, the conductive member being disposed close to the one ends of the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element and near a point of intersection where the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element meet when extended; and

a plurality of second antennas arranged on the flat part of the reflective member along an array of the plurality of first antennas, each of the plurality of second antennas being configured to transmit and receive radio waves in a second frequency band higher than the first frequency band, wherein

each of the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element included in each of the plurality of first antennas is a dipole antenna comprising:

two radiation parts;

a support part extending to the flat part of the reflective member, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion.

9. A sector antenna comprising:

an array antenna including a plurality of antennas arranged on a flat part of a reflective member, each of the plurality of antennas including a first antenna element, a second antenna element, and a conductive member, the first antenna element being configured to transmit and receive radio waves of a first polarization, the second antenna element being configured to transmit and receive radio waves of a second polarization different from the first polarization, one end of the second antenna element being located close to one end of the first antenna element, the conductive member being disposed close to the one ends of the first antenna element and the second antenna element and near a point of intersection where the first antenna element and the second antenna element meet when extended; and

a cover configured to cover the array antenna, wherein

each of the first antenna element and the second antenna element is a dipole antenna comprising:

two radiation parts;

a support part extending to the flat part of the reflective member, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion.

10. A dipole antenna comprising:

two radiation parts;

a support part extending to a flat part of a reflective member to which the support part is attached, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion;

wherein the dipole antenna further comprises: a spacer made of a dielectric and interposed between the base and the flat part of the reflective member, wherein

the spacer includes a base holding member configured to hold the base.

11. A dipole antenna comprising:

two radiation parts;

a support part extending to a flat part of a reflective member to which the support part is attached, the support part being configured to support the two radiation parts; and

a base configured to hold the support part relative to the flat part of the reflective member, wherein

each of the two radiation parts includes a first portion, a second portion, and a third portion, the first portion being parallel to the flat part of the reflective member, the second portion changing distance from the flat part as the second portion goes away from the support part, the third portion bending and extending from a distal end of the second portion;

wherein the dipole antenna further comprises: a spacer made of a dielectric and interposed between the base and the flat part of the reflective member, wherein

the spacer includes a spacer holding member configured to allow the spacer to be held on the reflective member.