Planar antenna
A planar antenna includes a dielectric substrate, a feed line on a first surface of the dielectric substrate that has a first and second lateral sides, three rectangular-shaped radiation elements arrayed on the first surface and provided at the first and second lateral sides to alternately protrude, and an electromagnetic band gap structure having an arrangement region on the first surface. The first surface includes a first adjacent region adjacent to the first lateral side and a second adjacent region adjacent to the second lateral side. The arrangement region includes a first arrangement region in the first adjacent region and a second arrangement region in the second adjacent region. Part of the first arrangement region is closer to the feed line with respect to a first imaginary line, and part of the second arrangement region is closer to the feed line with respect to a second imaginary line.
1 . A planar antenna comprising:
a dielectric substrate;
a feed line provided on a first surface of the dielectric substrate and having a first lateral side extending along a first direction and a second lateral side opposed to the first lateral side;
three or more radiation elements arrayed on the first surface along the first direction and provided at the first lateral side and the second lateral side so as to alternately protrude; and
an electromagnetic band gap structure having an arrangement region on the first surface, wherein
the first surface includes a first adjacent region adjacent to the first lateral side and a second adjacent region adjacent to the second lateral side,
the arrangement region includes a first arrangement region included in the first adjacent region and a second arrangement region included in the second adjacent region,
the first arrangement region is defined by a perimeter of the electromagnetic band gap structure in the first adjacent region,
the second arrangement region is defined by a perimeter of the electromagnetic band gap structure in the second adjacent region,
the three or more radiation elements include a plurality of first radiation elements protruding from the first lateral side toward the first adjacent region, and one or a plurality of second radiation elements protruding from the second lateral side toward the second adjacent region,
at least a part of the first arrangement region is positioned closer to the feed line with respect to a first imaginary line below, and
at least a part of the second arrangement region is positioned closer to the feed line with respect to a second imaginary line below,
the first imaginary line: a straight line parallel to the first direction and passing through the first adjacent region, an interval between the straight line and an imaginary center line below being twice w 1 below,
the second imaginary line: a straight line parallel to the first direction and passing through the second adjacent region, an interval between the straight line and the imaginary center line being twice w 2 below,
the imaginary center line: a straight line parallel to the first direction and passing through a center, in a second direction orthogonal to the first direction, of the feed line,
the w 1 : an interval between the imaginary center line and a leading edge of the plurality of first radiation elements, and
the w 2 : an interval between the imaginary center line and a leading edge of the one or the plurality of second radiation elements.
2 . The planar antenna according to claim 1 , wherein
at least a part of the first arrangement region is positioned closer to the feed line with respect to a third imaginary line below, and
at least a part of the second arrangement region is positioned closer to the feed line with respect to a fourth imaginary line below,
the third imaginary line: a straight line parallel to the first direction and passing through the leading edge of the plurality of first radiation elements, and
the fourth imaginary line: a straight line parallel to the first direction and passing through the leading edge of the one or the plurality of second radiation elements.
3 . The planar antenna according to claim 2 , wherein a part of the first arrangement region is positioned between the plurality of first radiation elements.
4 . The planar antenna according to claim 2 , wherein
a maximum value of a width dimension along the second direction of the first arrangement region is larger than a maximum value of a width dimension along the second direction of the plurality of first radiation elements, and
a maximum value of a width dimension along the second direction of the second arrangement region is larger than a maximum value of a width dimension along the second direction of the one or the plurality of second radiation elements.
5 . The planar antenna according to claim 1 , wherein the arrangement region further includes a third arrangement region connecting the first arrangement region and the second arrangement region so as to surround the feed line.
6 . The planar antenna according to claim 2 , wherein a part of the second arrangement region is positioned between the one or the plurality of second radiation elements.
7 . The planar antenna according to claim 2 , wherein the third imaginary line is a straight line parallel to the first direction and passing through a leading edge farthest from the imaginary center line out of leading edges of the plurality of first radiation elements.
8 . The planar antenna according to claim 2 , wherein the fourth imaginary line is a straight line parallel to the first direction and passing through a leading edge farthest from the imaginary center line out of leading edges of the one or the plurality of second radiation elements.
9 . The planar antenna according to claim 1 , wherein the w 1 is an interval between the imaginary center line and a leading edge farthest from the imaginary center line out of leading edges of the plurality of first radiation elements.
10 . The planar antenna according to claim 1 , wherein the w 2 is an interval between the imaginary center line and a leading edge farthest from the imaginary center line out of leading edges of the one or the plurality of second radiation elements.
11 . The planar antenna according to claim 1 , wherein each radiation element has a rectangular shape.
12 . The planar antenna according to claim 1 , wherein the electromagnetic band gap structure includes a plurality of unit cells arrayed on the first surface.
13 . The planar antenna according to claim 12 , wherein the first arrangement region and the second arrangement region each include a subset of the plurality of unit cells.
14 . The planar antenna according to claim 13 , wherein
the perimeter of the electromagnetic band gap structure in the first adjacent region is determined by outer edges of unit cells of the subset of the first arrangement region positioned at an outer edge of the electromagnetic band gap structure in the first adjacent region, and
the perimeter of the electromagnetic band gap structure in the second adjacent region is determined by outer edges of unit cells of the subset of the second arrangement region positioned at an outer edge of the electromagnetic band gap structure in the second adjacent region.
15 . The planar antenna according to claim 12 , wherein the plurality of unit cells are conductive patterns arranged on the first surface with a gap between adjacent unit cells.
16 . The planar antenna according to claim 15 , wherein the first arrangement region and the second arrangement region each include a subset of the conductive patterns.
17 . The planar antenna according to claim 16 , wherein
the perimeter of the electromagnetic band gap structure in the first adjacent region is determined by outer edges of conductive patterns of the subset of the first arrangement region positioned at an outer edge of the electromagnetic band gap structure in the first adjacent region, and
the perimeter of the electromagnetic band gap structure in the second adjacent region is determined by outer edges of conductive patterns of the subset of the second arrangement region positioned at an outer edge of the electromagnetic band gap structure in the second adjacent region.