Vehicle
A vehicle includes a vehicle body, a drive mechanism, a windshield, an antenna part provided in a vehicle interior, and a reflection suppression layer including a dielectric layer that closely adheres to a surface on the antenna part side of the windshield. The dielectric layer has a refractive index that is lower than a refractive index of a glass layer of the windshield and higher than a refractive index of air. The dielectric layer has a thickness that allows reflection of the transmission wave to be suppressed by interference between a reflected wave generated by reflection of the transmission wave on an interface on the opposite side of the innermost glass layer of the windshield to the antenna part side, and a reflected wave generated by reflection of the transmission wave on a surface on the antenna part side of the dielectric layer.
1. A vehicle comprising:
a vehicle body;
a drive mechanism for moving the vehicle body;
a windshield located between a vehicle interior and an outside, at least a surface on the vehicle interior side of the windshield being a surface of a glass layer;
an antenna part provided in the vehicle interior and for transmitting a transmission wave from the vehicle interior through the windshield to the outside, the transmission wave being a radio wave in a millimeter waveband, and receiving a reflected wave that enters the vehicle interior from the outside through the windshield;
a reflection suppression layer composed of at least one dielectric layer that closely adheres to the surface on the antenna part side of the windshield;
a high-frequency oscillator for outputting high-frequency electric power to the antenna part; and
a receiver for receiving input of a radio wave received by the antenna part and outputting a received signal,
wherein the at least one dielectric layer has a refractive index that is lower than a refractive index of the glass layer and higher than a refractive index of air,
the transmission wave has a horizontal polarization component greater than a vertical polarization component thereof with respect to the reflection suppression layer, and
Formula 27 is satisfied:
λ
2
(
M
+
5
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
M
+
3
8
)
and
λ
2
(
N
+
9
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
+
∑
j
=
1
m
d
sj
n
sj
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
N
+
7
8
)
[
Formula
27
]
where θ i is an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe, n i is the refractive index of air, m is the number of the at least one dielectric layer, d sj is a thickness of a j-th dielectric layer counting from the antenna part side, n sj is a refractive index of the j-th dielectric layer, d g is a thickness of the glass layer, n g is a refractive index of the glass layer, λ is a wavelength of the transmission wave in air, and M and N are integers of 0 or more.
2. The vehicle according to claim 1 , wherein
the variable j is 1.
3. The vehicle according to claim 2 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
4. The vehicle according to claim 1 , wherein
the variable j is greater than or equal to 2, and
each of the second and subsequent dielectric layers counting from the antenna part side has a refractive index higher than a refractive index of a dielectric layer that is adjacent to the antenna part side of the dielectric layer.
5. The vehicle according to claim 4 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
6. The vehicle according to claim 4 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
7. The vehicle according to claim 1 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
8. The vehicle according to claim 7 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
9. The vehicle according to claim 2 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
10. The vehicle according to claim 1 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
11. A vehicle comprising:
a vehicle body;
a drive mechanism for moving the vehicle body;
a windshield located between a vehicle interior and an outside, at least a surface on the vehicle interior side of the windshield being a surface of a glass layer;
an antenna part provided in the vehicle interior and for transmitting a transmission wave from the vehicle interior through the windshield to the outside, the transmission wave being a radio wave in a millimeter waveband, and receiving a reflected wave that enters the vehicle interior from the outside through the windshield;
a reflection suppression layer composed of at least one dielectric layer that closely adheres to the surface on the antenna part side of the windshield;
a high-frequency oscillator for outputting high-frequency electric power to the antenna part; and
a receiver for receiving input of a radio wave received by the antenna part and outputting a received signal,
wherein the at least one dielectric layer has a refractive index that is lower than a refractive index of the glass layer and higher than a refractive index of air,
the transmission wave has a vertical polarization component greater than a horizontal polarization component thereof with respect to the reflection suppression layer, and
Formulas 28 and 29 are satisfied:
If
θ
i
is
greater
than
or
smaller
than
both
of
sin
-
1
(
n
r
n
g
n
i
n
g
2
+
n
r
2
)
and
tan
-
1
n
s
1
n
i
,
λ
2
(
M
+
5
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
M
+
3
8
)
and
λ
2
(
N
+
9
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
+
∑
j
=
1
m
d
sj
n
sj
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
N
+
7
8
)
[
Formula
28
]
If
θ
i
is
a
value
between
or
equal
to
one
of
sin
-
1
(
n
r
n
g
n
i
n
g
2
+
n
r
2
)
and
tan
-
1
n
s
1
n
i
,
λ
2
(
M
+
9
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
M
+
7
8
)
and
λ
2
(
N
+
5
8
)
>
d
g
n
g
2
-
n
i
2
sin
2
θ
i
+
∑
j
=
1
m
d
sj
n
sj
2
-
n
i
2
sin
2
θ
i
>
λ
2
(
N
+
3
8
)
[
Formula
29
]
where θ i is an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe, n i is a refractive index of air, m is the number of the at least one dielectric layer, d sj is a thickness of a j-th dielectric layer counting from the antenna part side, n sj is a refractive index of the j-th dielectric layer, d g is a thickness of the glass layer, n g is a refractive index of the glass layer, n r is a refractive index of a dielectric layer or an air layer that is adjacent to an opposite side of the glass layer to the antenna part side, λ is a wavelength of the transmission wave in air, and M and N are integers of 0 or more.
12. The vehicle according to claim 11 , wherein
the variable j is 1.
13. The vehicle according to claim 12 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
14. The vehicle according to claim 11 , wherein
the variable j is greater than or equal to 2, and
each of the second and subsequent dielectric layers counting from the antenna part side has a refractive index higher than a refractive index of a dielectric layer that is adjacent to the antenna part side of the dielectric layer.
15. The vehicle according to claim 14 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
16. The vehicle according to claim 14 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
17. The vehicle according to claim 11 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
18. The vehicle according to claim 17 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.
19. The vehicle according to claim 12 , wherein
the incident angle of the transmission wave on the reflection suppression layer at the center of the main lobe is greater than 10 degrees.
20. The vehicle according to claim 11 , further comprising:
an antenna cover located between the antenna part and the windshield and covering a front of the antenna part,
wherein the antenna cover also serves as the reflection suppression layer.