Vehicle window glass

1 . A window glass for a vehicle, comprising: a glass plate; a light shielding layer formed on the glass plate; and a planar antenna including a planar conductor having formed therein a hollowed-out portion with at least one hole,

wherein, in plan view of the glass plate, when a region including the light shielding layer is assumed as a light shielding region; and a region including no light shielding layer is assumed as a transmission region,

the planar antenna is arranged to lie across a boundary between the light shielding region and the transmission region, and has a first conductor part overlapping the light shielding region and a second conductor part overlapping the transmission region, and

wherein, when an area of overlap of the planar antenna with the light shielding region is assumed as a first overlap area; an area of overlap of the planar antenna with the transmission region is assumed as a second overlap area; a ratio of an area of the first conductor part to the first overlap area is assumed as a first conductor density; and a ratio of an area of the second conductor part to the second overlap area is assumed as a second conductor density,

the second conductor density is lower than the first conductor density,

wherein the hollowed-out portion includes a first hollowed-out portion formed in the first conductor part and a second hollowed-out portion formed in the second conductor part,

wherein an area of the second hollowed-out portion is larger than an area of the first hollowed-out portion,

wherein each of the first hollowed-out portion and the second hollowed-out portion has a plurality of holes, and

wherein an area of the widest one of the plurality of holes in the second hollowed-out portion is larger than an area of the widest one of the plurality of holes in the first hollowed-out portion.

2 . The window glass for a vehicle according to claim 1 , wherein an area of the narrowest one of the plurality of holes in the second hollowed-out portion is larger than an area of the narrowest one of the plurality of holes in the first hollowed-out portion.

3 . The window glass for a vehicle according to claim 1 , wherein the planer antenna has a feeding conductor part with a feeding point and a ground conductor part with a ground point, and

at least one of the feeding point and the ground point is included in the first conductor part.

4 . The window glass for a vehicle according to claim 1 , wherein the boundary is along at least a part of an outer edge of the hollowed-out portion.

5 . The window glass for a vehicle according to claim 4 , wherein the hollowed-out portion in the transmission region has only a single hole in a closed loop region surrounded by the boundary and an outer edge of the planar antenna.

6 . The window glass for a vehicle according to claim 1 , wherein the hollowed-out portion has a plurality of holes aligned along the boundary.

7 . The window glass for a vehicle according to claim 1 , wherein the hollowed-out portion has a plurality of holes aligned in a direction substantially orthogonal to the boundary.

8 . The window glass for a vehicle according to claim 1 , wherein the following formula is satisfied:

S

v

/

S

c

⁢

2

≥

1.

where S v is a total area of the holes in the transmission region; and S c2 is the area of the second conductor part.

9 . The window glass for a vehicle according to claim 8 , wherein the holes in the transmission region are substantially uniformly arranged.

10 . The window glass for a vehicle according to claim 1 , wherein the following formula is satisfied:

D

1

/

D

2

≥

1.03

where D 1 is the first conductor density; and D 2 is the second conductor density.

11 . The window glass for a vehicle according to claim 1 , wherein the planar antenna is configured to transmit and receive radio waves of 600 MHz or higher.

12 . The window glass for a vehicle according to claim 11 , wherein the planar antenna is configured to transmit and receive radio waves of 6 GHz or lower.

13 . The window glass for a vehicle according to claim 1 , comprising a plurality of the planar antennas arranged on the glass plate.

14 . The window glass for a vehicle according to claim 1 , wherein the glass plate is a glass plate for a windshield, a side glass, a rear glass or a roof glass of a vehicle.