Vehicle
A vehicle includes a windshield, at least a surface on a vehicle interior side thereof being a surface of glass; an antenna part provided in the vehicle interior and for transmitting a transmission wave, which is a radio wave in a millimeter waveband, from the vehicle interior through the windshield to the outside; and a reflection suppression layer including a dielectric layer that adheres to the surface on the antenna part side of the windshield. The dielectric layer has a refractive index lower than that of the glass. 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 between the dielectric layer and the windshield, 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 glass;
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 including a dielectric layer that 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 dielectric layer has a refractive index that is lower than a refractive index of the glass and higher than a refractive index of air; and
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 at which the dielectric layer adheres to the surface of the windshield, and a reflected wave generated by reflection of the transmission wave on a surface on the antenna part side of the dielectric layer.
2. The vehicle according to claim 1 , wherein
the reflection suppression layer includes another dielectric layer that adheres to the surface on the antenna part side of the dielectric layer; and
the another 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 at which the another dielectric layer adheres to the surface of the dielectric layer, and a reflected wave generated by reflection of the transmission wave on a surface on the antenna part side of the another dielectric layer.
3. 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 glass;
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 including a dielectric layer that adheres to the surface on the antenna part side of the glass;
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 dielectric layer has a refractive index that is lower than a refractive index of the glass and higher than a refractive index of air;
the antenna part includes a transmitting antenna for transmitting the transmission wave;
the transmission wave has a vertical polarization component greater than a horizontal polarization component thereof with respect to the reflection suppression layer; and
relationships expressed by Formulas 24 and 25 are satisfied, where θ a is an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna, n s is the refractive index of the dielectric layer, n g is the refractive index of the glass, n i is a refractive index of a medium that is adjacent to the dielectric layer on the antenna part side, λ is a wavelength of the transmission wave in air, N is an integer of 0 or more, and d is a thickness of the dielectric layer:
If
n
i
<
n
s
<
n
g
and
θ
a
is
smaller
than
or
greater
than
both
of
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
and
sin
-
1
(
n
s
sin
(
tan
-
1
n
g
n
s
)
)
,
(
2
N
+
3
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
5
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
,
and
if
n
i
<
n
i
<
n
g
and
θ
a
is
a
value
between
or
equal
to
one
of
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
and
sin
-
1
(
n
s
sin
(
tan
-
1
n
g
n
s
)
)
,
(
2
N
+
7
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
9
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
[
Formula
24
]
and
If
n
i
>
n
s
<
n
g
and
θ
a
is
smaller
than
or
greater
than
both
of
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
and
sin
-
1
(
n
s
sin
(
tan
-
1
n
g
n
s
)
)
,
(
2
N
+
7
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
9
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
,
and
if
n
i
>
n
i
<
n
g
and
θ
a
is
a
value
between
or
equal
to
one
of
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
and
sin
-
1
(
n
s
sin
(
tan
-
1
n
g
n
s
)
)
,
(
2
N
+
3
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
5
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
.
[
Formula
25
]
4. The vehicle according to claim 3 , wherein
the reflection suppression layer includes another dielectric layer that adheres to a surface on the antenna part side of the dielectric layer, and
relationships expressed by Formulas 26 and 27 are satisfied, where n i is a refractive index of the another dielectric layer, n i2 is a refractive index of a medium that is adjacent to the another dielectric layer on the antenna part side, and d i is a thickness of the another dielectric layer:
If
n
i
2
>
n
i
>
n
s
or
n
i
2
<
n
i
<
n
s
and
θ
a
is
smaller
than
or
greater
than
both
of
sin
-
1
(
n
i
2
sin
(
tan
-
1
n
i
n
i
2
)
)
and
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
,
(
2
N
+
3
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
5
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
,
and
if
n
i
2
>
n
i
>
n
s
or
n
i
2
<
n
i
<
n
s
and
θ
a
is
a
value
between
or
equal
to
one
of
sin
-
1
(
n
i
2
sin
(
tan
-
1
n
i
n
i
2
)
)
and
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
,
(
2
N
+
7
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
9
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
[
Formula
26
]
and
If
n
i
2
<
n
i
>
n
s
or
n
i
2
>
n
i
<
n
s
and
θ
a
is
smaller
than
or
greater
than
both
of
sin
-
1
(
n
i
2
sin
(
tan
-
1
n
i
n
i
2
)
)
and
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
,
(
2
N
+
7
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
9
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
,
and
if
n
i
2
<
n
i
>
n
s
or
n
i
2
>
n
i
<
n
s
and
θ
a
is
a
value
between
or
equal
to
one
of
sin
-
1
(
n
i
2
sin
(
tan
-
1
n
i
n
i
2
)
)
and
sin
-
1
(
n
i
sin
(
tan
-
1
n
s
n
i
)
)
,
(
2
N
+
3
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
5
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
.
[
Formula
27
]
5. 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 glass;
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 including a dielectric layer that adheres to the surface on the antenna part side of the glass;
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 dielectric layer has a refractive index that is lower than a refractive index of the glass and higher than a refractive index of air;
the antenna part includes a transmitting antenna for transmitting the transmission wave;
the transmission wave has a horizontal polarization component greater than or equal to a vertical polarization component thereof with respect to the reflection suppression layer; and
a relationship expressed by Formula 28 is satisfied, where θ a is an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna, n s is the refractive index of the dielectric layer, n g is the refractive index of the glass, n i is a refractive index of a medium that is adjacent to the dielectric layer on the antenna part side, λ is a wavelength of the transmission wave in air, N is an integer of 0 or more, and d is a thickness of the dielectric layer:
If
n
i
<
n
s
<
n
g
,
(
2
N
+
3
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
5
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
,
and
if
n
i
>
n
s
<
n
g
,
(
2
N
+
7
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
≤
d
≤
(
2
N
+
9
4
)
n
s
λcos
(
sin
-
1
(
1
n
s
sin
θ
a
)
)
4
(
n
s
2
-
sin
2
θ
a
)
.
[
Formula
28
]
6. The vehicle according to claim 5 , wherein
the reflection suppression layer includes another dielectric layer that adheres to a surface on the antenna part side of the dielectric layer; and
a relationship expressed by Formula 29 is satisfied, where n, is a refractive index of the another dielectric layer, n i2 is a refractive index of a medium that is adjacent to the another dielectric layer on the antenna part side, and d i is a thickness of the another dielectric layer:
If
n
i
2
>
n
i
>
n
s
or
n
i
2
<
n
i
<
n
s
,
(
2
N
+
3
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
5
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
,
and
if
n
i
2
<
n
i
>
n
s
or
n
i
2
>
n
i
<
n
s
,
(
2
N
+
7
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
≤
d
i
≤
(
2
N
+
9
4
)
n
i
λcos
(
sin
-
1
(
1
n
i
sin
θ
a
)
)
4
(
n
i
2
-
sin
2
θ
a
)
.
[
Formula
29
]
7. The vehicle according to claim 2 , wherein
the another dielectric layer has a refractive index that is lower than the refractive index of the dielectric layer and higher than the refractive index of air.
8. The vehicle according to claim 4 , wherein
the another dielectric layer has a refractive index that is lower than the refractive index of the dielectric layer and higher than the refractive index of air.
9. The vehicle according to claim 6 , wherein
the another dielectric layer has a refractive index that is lower than the refractive index of the dielectric layer and higher than the refractive index of air.
10. The vehicle according to claim 1 , wherein
the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
11. The vehicle according to claim 2 , wherein
the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
12. The vehicle according to claim 3 , wherein the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
13. The vehicle according to claim 4 , wherein
the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
14. The vehicle according to claim 5 , wherein
the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
15. The vehicle according to claim 6 , wherein
the antenna part includes a transmitting antenna for transmitting the transmission wave; and
an incident angle of the transmission wave on the reflection suppression layer at a center of a main lobe of the transmitting antenna is greater than 10 degrees.
16. 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.
17. 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.
18. The vehicle according to claim 3 , 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 5 , 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.
20. The vehicle according to claim 10 , 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.