Antenna device
An antenna device includes: a first planar antenna for a linearly polarized wave, the first planar antenna including a first feeding portion; and a second planar antenna for a linearly polarized wave, the second planar antenna including a second feeding portion that overlaps the first feeding portion in a plan view when viewed in a direction perpendicular to a predetermined surface of the first planar antenna, wherein the linearly polarized wave of the first planar antenna and the linearly polarized wave of the second planar antenna intersect each other.
1 . An antenna device comprising:
a first planar antenna for a linearly polarized wave, the first planar antenna including a first feeding portion; and
a second planar antenna for a linearly polarized wave, the second planar antenna including a second feeding portion that overlaps the first feeding portion in a plan view when viewed in a direction perpendicular to a predetermined surface of the first planar antenna, wherein
at least one of the first planar antenna or the second planar antenna includes
an outer conductor-side element configured to be coupled with an outer conductor of a feeding line, and
an inner conductor-side element configured to be coupled with a core of the feeding line,
the linearly polarized wave of the first planar antenna and the linearly polarized wave of the second planar antenna intersect each other,
for each of the at least one of the first planar antenna or the second planar antenna that includes the outer conductor-side element and the inner conductor-side element, a respective one of the first feeding portion or the second feeding portion of that antenna is located between the outer conductor-side element and the inner conductor-side element of that antenna,
an outer shape of the outer conductor-side element and an outer shape of the inner conductor-side element of the at least one of the first planar antenna or the second planar antenna are substantially symmetrical with each other, with respect to a first axis passing through the respective one of the first feeding portion or the second feeding portion, and
each of the outer conductor-side element and the inner conductor-side element has a coupling portion configured to be coupled with the feeding line.
2 . The antenna device according to claim 1 , wherein
each of the first planar antenna and the second planar antenna includes
an outer conductor-side element configured to be coupled with the outer conductor of the feeding line, and
an inner conductor-side element configured to be coupled with the core of the feeding line,
the first feeding portion is located between the outer conductor-side element and the inner conductor-side element of the first planar antenna,
the second feeding portion is located between the outer conductor-side element and the inner conductor-side element of the second planar antenna,
an outer shape of the outer conductor-side element and an outer shape of the inner conductor-side element of the first planar antenna are substantially symmetrical with each other, with respect to the first axis passing through the first feeding portion, and
an outer shape of the outer conductor-side element and an outer shape of the inner conductor-side element of the second planar antenna are substantially symmetrical with each other, with respect to a second axis passing through the second feeding portion.
3 . The antenna device according to claim 2 , wherein
at least one of the outer conductor-side element or the inner conductor-side element has a slit, and
the slit has
an open end at an outer edge of the at least one of the outer conductor-side element or the inner conductor-side element including the slit, and
a closed end inside the at least one of the outer conductor-side element or the inner conductor-side element.
4 . The antenna device according to claim 3 , wherein
in the first planar antenna, the coupling portion of the at least one of the outer conductor-side element or the inner conductor-side element is located between the slit and the first feeding portion.
5 . The antenna device according to claim 4 , further comprising:
a third axis substantially perpendicular to the first axis, the third axis passing through the first feeding portion in the plan view of the first planar antenna, wherein
at least part of a path of the slit from the open end to the closed end extends in at least a region that is on a side opposite to the open end relative to the third axis.
6 . The antenna device according to claim 3 , further comprising:
a third axis substantially perpendicular to the first axis, the third axis passing through the first feeding portion in the plan view of the first planar antenna, wherein
in the first planar antenna, the slit includes at least
a portion extending from the open end toward the third axis, and
a portion extending in a direction away from the first feeding portion.
7 . The antenna device according to claim 3 , wherein
the at least one of the outer conductor-side element or the inner conductor-side element in which the slit is formed has at least one rib, and
the at least one rib has a thickness larger than a thickness of a portion other than the at least one rib in the element.
8 . The antenna device according to claim 7 , wherein
the at least one rib includes two or more ribs,
the at least one of the outer conductor-side element or the inner conductor-side element in which the slit is formed includes the two or more ribs, and
the slit is located between two ribs adjacent to each other of the two or more ribs.
9 . The antenna device according to claim 3 , wherein the slit is formed only in the inner conductor-side element.
10 . The antenna device according to claim 2 , wherein
in each of the first planar antenna and the second planar antenna
the coupling portion of the outer conductor-side element is an outer conductor-side coupling portion at which the feeding line is coupled to the outer conductor-side element, and
the coupling portion of the inner conductor-side element is an inner conductor-side coupling portion at which the feeding line is coupled to the inner conductor-side element,
the first feeding portion is located at a center between the outer conductor-side coupling portion and the inner conductor-side coupling portion in the first planar antenna, and
the second feeding portion is located at a center between the outer conductor-side coupling portion and the inner conductor-side coupling portion in the second planar antenna.
11 . The antenna device according to claim 10 , wherein
in at least one of the outer conductor-side element or the inner conductor-side element, a separating portion to separate the at least one of the coupling portions from a region other than the coupling portion is formed in part of a periphery of the coupling portion.
12 . The antenna device according to claim 2 , wherein
each of the outer conductor-side element and the inner conductor-side element in the first planar antenna has a curved outer edge convex toward the first feeding portion, and
each of the outer conductor-side element and the inner conductor-side element in the second planar antenna has a curved outer edge convex toward the second feeding portion.
13 . The antenna device according to claim 1 , wherein
in the plan view, the second planar antenna is arranged at an angle larger than 0° and smaller than 180° relative to the first planar antenna about the first feeding portion or the second feeding portion.
14 . The antenna device according to claim 1 , wherein
at least one of the outer conductor-side element or the inner conductor-side element has a slit, and
the slit has
an open end at an outer edge of the at least one of the outer conductor-side element or the inner conductor-side element including the slit, and
a closed end inside the at least one of the outer conductor-side element or the inner conductor-side element.
15 . The antenna device according to claim 14 , wherein
in the first planar antenna, the coupling portion of the at least one of the outer conductor-side element or the inner conductor-side element is located between the slit and the first feeding portion.