Vehicle antenna device and in-vehicle system
To suppress noise included in an antenna provided on a glass plate. A vehicle antenna device comprising a glass plate for a vehicle, a first antenna capable of receiving or transmitting radio waves of a first frequency band, provided on the glass plate, and an electric circuit which attenuates a signal of a second frequency band including a frequency band higher than the first frequency band, wherein the first antenna has a first feeding portion to be electrically connected to a signal line of a transmission line and a first element connected to the first feeding portion, and the electric circuit is provided at least one of between the first feeding portion or the vicinity of the first feeding portion and a ground portion, and between the first feeding portion and the signal line.
1 . A vehicle antenna device comprising a glass plate for a vehicle,
a first antenna capable of receiving or transmitting radio waves of a first frequency band, provided on the glass plate, and
an electric circuit which attenuates a signal of a second frequency band including a frequency band higher than the first frequency band,
wherein the first antenna has a first feeding portion to be electrically connected to a signal line of a transmission line and a first element connected to the first feeding portion, and
the electric circuit is provided at least one of between the first feeding portion or the vicinity of the first feeding portion and a ground portion, and between the first feeding portion and the signal line.
2 . The vehicle antenna device according to claim 1 , wherein the electric circuit includes a capacitive coupling between the first feeding portion or the vicinity of the first feeding portion and the ground portion.
3 . The vehicle antenna device according to claim 2 , wherein the electric circuit includes a conductor electrically connected to the first feeding portion, and a dielectric layer interposed between the conductor and the ground portion.
4 . The vehicle antenna device according to claim 3 , wherein the dielectric layer includes glass.
5 . The vehicle antenna device according to claim 4 , wherein the glass plate has a first glass plate, a second glass plate which faces the first glass plate, and an interlayer provided between the first glass plate and the second glass plate,
the first feeding portion is provided on a main surface of the second glass plate opposite from the interlayer,
the dielectric layer includes the second glass plate, and
the conductor is disposed between the first glass plate and the second glass plate.
6 . The vehicle antenna device according to claim 4 , wherein the glass plate has a first glass plate, a second glass plate which faces the first glass plate, and an interlayer provided between the first glass plate and the second glass plate,
the first feeding portion is disposed between the first glass plate and the second glass plate,
the conductor is disposed on a main surface of the second glass plate opposite from the interlayer, and
the dielectric layer is positioned between the main surface and the ground portion.
7 . The vehicle antenna device according to claim 3 , wherein the conductor is an extending conductor extending from the first feeding portion or the vicinity of the first feeding portion.
8 . The vehicle antenna device according to claim 1 , wherein the ground portion includes a metal portion on a vehicle side.
9 . The vehicle antenna device according to claim 1 , wherein the first antenna has a second feeding portion to be electrically connected to a ground conductor of the transmission line, and
the ground portion includes the second feeding portion.
10 . The vehicle antenna device according to claim 9 , wherein the first antenna has a second element to be electrically connected to the second feeding portion.
11 . The vehicle antenna device according to claim 1 , wherein the second frequency band is 617 MHz and higher.
12 . The vehicle antenna device according to claim 11 , wherein the second frequency band includes a 2.4 GHz band.
13 . The vehicle antenna device according to claim 11 , wherein the second frequency band includes at least one of a 5.2 GHz band, a 5.3 GHZ band, and a 5.6 GHz band.
14 . The vehicle antenna device according to claim 1 , wherein the electric circuit decreases at least part of receiving power of the second frequency band by 3 dB or more as compared with a case where no electric circuit is provided.
15 . The vehicle antenna device according to claim 1 , wherein the first frequency band incudes a frequency band included in VHF band or UHF band.
16 . The vehicle antenna device according to claim 1 , which has a second antenna capable of transmitting or receiving radio waves of the second frequency band, provided on the glass plate.
17 . An in-vehicle system comprising the vehicle antenna device as defined in claim 1 , and an electronic device disposed separately from the first antenna,
wherein the electronic device emits electromagnetic waves of the second frequency band.
18 . The in-vehicle system according to claim 17 , wherein the distance between the first antenna and the electronic device is 100 mm or less.
19 . The in-vehicle system according to claim 17 , wherein the electronic device is provided on the glass plate.