DESCRIPTION]
[Title of Invention] REFLECTOR DEVICE, COMMUNICATION
SYSTEM USING THE SAME AND COMMUNICATION METHOD USING
THE SAME
5 [Technical Field]
[OOO 11
The present invention relates to a reflector device, a communication
system using the reflector device, and a communication method using the
reflector device and, in particular, to a communication system and
10 communication method that relay using reflection by a reflector device.
[Background Art]
[0002]
A point-to-point system that uses parabolic antennas is used as a
mobile backhaul radio system. 111 order to provide good-quality
15 communication, line of sight between antennas is required. In other
words, in order to ensure line of sight, antennas need to be installed in
elevated locations. Modern mobile station cells have been reduced to
small cells such as picocells and femtocells. Consequently, base stations
in urban regions need to be installed at lower locations. This poses a
20 problem that line-of-sight environments cannot be ensured and that it
makes it difficult to provide radio commulzication in point-to-point
systems.
[0003]
Patent Literature 1 (PTLl) proposes that a passive repeater made up
25 of two antennas coupled back to back is provided at a midpoint between a
transmitting ante~lnaa nd a receiving antenna to prevent disconnectio~lsd ue
to fading.
[0004]
The use of the repcatcr as described in Patent Literature 1 (PTLl)
3
allows good-quality communication even when the angle of incidence is
large. However, the passive repeater, which is made up of two antennas
coupled back to back, has the problem of high cost because it requires two
antennas.
5 [0005]
A related technique that addresses the problem is a reflector relay
method described in Non Patent Literature 1 (NPL1) which is a method for
relaying microwaves between two points that are not on a direct
line-of-sight path. Patent Literature 2 (PTL2) proposes that a reflector
10 having two reflective surfaces that face each other at an angle of
approximately 90 degrees is used as a relay station, one terminal station
transmits a signal toward the reflector and the signal reflected by the two
reflective surfaces is received at another terminal station. Patent
Literature 3 (PTL3) proposes that a radio wave from a wireless base station
15 is reflected by a curved reflector plate to eliminate blind regions in a
mobile communication system. Patent Literature 4 (PTL4) proposes an
RFID (radio frequency identification) communication system ill which a
reflector plate is attached to a motor shaft at an inclination angle to the
motor shaft and an electroinagnetic wave from an antenna is reflected
20 toward a11 KFID tag by the reflector plate which rotates about the motor
shaft.
[OOOGl
Point-to-point systems can be provided in non-line-of-sight
environments by using the repeater systems described in Patent Literatures
25 2 to 4 (PTL2 to PTL4) and Non Patent Literature 1 (NPL1).
[Citation List]
[Patent Literature]
[0007]
[P'I'LI] Japanese Laid-Open Patent Publication No. Sho 63-246040
4
[PTL2] Japanese Laid-Open Patent Publication No. Sho 58-73205
[PTL3] Japanese Laid-Open Patent Publication No. Hei 7- 154320
[PTL4] Japanese Laid-Open Patent Publication No. 2007-299232
[Non Patent Literature]
5 [0008]
[NPLI] Tomohiro Komai, "Passive Reflector to Reduce Fading due to
Angle of Incidence Variations on Microwave Links", Journal of The
Institute of Electronics, Information and Communication Engineers, B-11,
Vol. J74-B-11, No. 8, pp. 447-453, August, 1991
10 [Summary of Invention]
[Technical Problem]
[0009]
However, the related techniques described above have the following
problems.
I5 [0010]
When any of the reflector plates proposed in Patent Literatures 2
to 4 (PTL2 to PTL4) and Non Patent Literature 1 (NPLI) is used, there is a
problem that the cross-section of a radio wave arriving at a large angle of
incidence is so small that it is difficult to provide good-quality
20 communication. Conversely, the size of the reflector plates needs to be
increased in order to provide good-quality communication.
fool 11
An object of the present invention is to provide a reflector device
that solves the above-described problem that it is difficult to provide
25 good-quality communication at low cost by using a reflector plate in
non-line-of-sight communication when the angle of incidence of a radio
wave is large, and to provide a communication system using the reflector
device and a communication nlethod using the reflector device.
[Solution to Problem]
[OO 121
To achieve the object described above, a reflector device according
to the present invention includes a first reflector plate and a second
5 reflector plate to each of which a reflective surface is attached at a
predetermined inclination angle to an axis of rotation, wherein the first
reflector plate and the second reflector plate are positioned to face one
another, and at least one of the first reflector plate and the second reflector
plate is rotatable about the axis of rotation.
10 [0013]
A communication system using a reflector device according to the
present invention includes: a reflector device including a first reflector
plate and a second reflector plate to each of which a reflective surface is
attached at a predetermined inclination angle to an axis of rotation,
15 wherein the first reflector plate and the second reflector plate are
positioned to face one another, and at least one of the first reflector plate
and the second reflector plate is rotatable about the axis of rotation;
a first antenna transmitting a radio wave to the reflective surface of
the first reflector plate of the reflector device; and
20 a secoi~da ntenna receiving the radio wave reflected by the first
reflector plate of the reflector device and then reflected by the reflective
surface of the second reflector plate.
[00 141
A coinmunication method according to the present invention
25 reflects a horizontally incident wave in a vertical direction as a first
reflected wave,
reflects the first reflected wave in a horizontal direction as a second
reflected wave, and
emits the second reflected wave in a direction that is not parallel to
the incident wave.
[OO 151
A communication method using a reflector device according to the
present invention is a communication method using: a reflector device
5 including a first reflector plate and a second reflector plate to each of
which a reflective surface is attached at a predetermined inclination angle
to an axis of rotation, wherein the first reflector plate and the second
reflector plate are positioned to face one another, and at least one of the
first reflector plate and the second reflector plate is rotatable about the
10 axis of rotation;
a first antenna transmitting a radio wave to the reflective surface of
the first reflector plate of the reflector device; and
a second antenna receiving the radio wave reflected by the first
reflector plate of the reflector device and then reflected by the reflective
15 surface of the second reflector plate,
wherein at least one of the first reflector plate and the second
reflector plate of the reflector device is horizontally rotated to direct a
radio wave to the first antenna and the second antenna;
a radio wave is transmitted from the first antenna to the reflective
20 surface of the first reflector plate of the reflector device; and
the radio wave reflected by the first reflector plate of the reflector
device and further reflected by the reflective surface of the second
reflector plate is received by the second antenna.
[Advantageous Effects of Invention]
25 [0016]
The present invention can provide a reflector device that provides
good-quality communication at low cost in non-line-of-sight
communication using reflector plates even when the angle of incidence of
radio waves is large, and a communication system using the reflector
7
device and a communication method using the communication system.
[Brief Description of Drawings]
[0017]
Fig. 1 is an external view of a reflector device according to a first
5 exemplary embodiment of the present invention.
Fig. 2 is an external view for illustrating an operation of the
reflector device in Fig. 1 in further detail.
Fig. 3 is an external view for illustrating a communication system
and a communication method that use the reflector device according to the
10 first exemplary embodiment of the present invention.
Fig. 4 is an external view for illustrating a communication system
and a communication method that use a reflector device according to a
second exemplary embodiment of the present invention.
[Description of Embodiments]
15 LO01 81
Preferred exemplary e~nbodinlentso f the present invention will be
described in detail with reference to drawings.
[OO 191

2 0 A reflector device according to a first exemplary embodiment of the
present invention, a c o m n ~ u ~ ~ i c a tsiyosnt em using the reflector device, and
a communication method using the reflector device will be described first
with reference to drawings. Fig. 1 is an external view of a reflector
device according to the first exemplary embodiment of the present
25 invention and Fig. 2 is an external view for i l l ~ ~ s t r a t i nagn operation of the
reflector device in Fig. 1 in further detail. Fig. 3 is an external view for
illustrating a colnlnunication system and a co~nmunication method that use
a reflector device according to the first exemplary embodi~nento f the
present invention.
8
[0020]
The reflector device 10 of this exemplary embodiment includes a
first reflector plate 1 and a second reflector plate 2. The first reflector
plate 1 and the second reflector plate 2 are attached at a predetermined
5 inclination angle to an axis of rotation, have reflective surfaces, and are
disposed in such a way that the reflective surfaces face each other. At
least one of the plates is rotatable about the axis of rotation. The
predetermined inclination angle in this exemplary embodiment i s 45
degrees. The reflector device 10 further includes a first support 3
10 including a mechanism that horizontally rotates while keeping the
inclination of the first reflector plate 1 at 45 degrees, a second support 4
including a mechanism that horizontally rotates while keeping the
inclination of the second reflector plate 2 at 45 degrees, and a radome 5
housing the first reflector plate 1, the second reflector plate 2, the first
15 support 3 and the second support 4.
[002 11
'The metal plate col~stitutingt he first reflector plate 1 is inclined at
45 degrees so that the first reflector plate 1 reflects a horizontal incident
radio wave vcrtically dow~lwards. The metal plate is elliptical in shape
20 so that a cross section of the radio wave is circular as viewed from the
direction of propagation. The second reflector plate 2 is a metal plate
inclined at 45 degrees so that a radio wave reflected by the first reflector
plate 1 and propagating vertically downward is reflected in the horizontal
direction. The metal plate is elliptical in shape so that a cross section of
25 the radio wave is circular as viewed from the direction of propagation.
100221
The first support 3 includes a mechanism that horizontally rotates
while keeping the inclination of the first reflector plate 1. The second
support 4 includes a mechanism that l~orizontallyr otates while keeping the
9
inclination of the second reflector plate 2. The rotating mechanislns may
be provided for both of the first support 3 and second support 4. Since
the angular relation between the first reflector plate 1 and the second
reflector plate 2 is relative, the rotating mechanism may be provided only
5 for one of the first support 3 and the second support 4.
[0023]
The radome 5 is cylindrical in shape, houses the first reflector plate
1, the second reflector plate 2, the first support 3 and the fourth support 4,
and protects them from weather. The radome 5 is made of plastic resin
10 such as FRP (fiberglass reinforced plastic) or polycarbonate.
[0024]
An operation of the reflector device 10 of this exemplary
embodiment will now be described. As illustrated in Fig. 1, a
horizontally incident radio wave is reflected by the first reflector plate 1,
15 propagates vertically downward, reflected by the second reflector plate 2
and propagates horizontally. The second reflector plate 2a horizontally
rotated wllile keeping the inclination of the second reflector plate 2 at 45
degrces is represented by a dashed line in Fig. 2. In this setting, a radio
wave which has been reflected by the first reflector plate 1, has propagated
20 vertically downward, and has been further reflected by the second reflector
plate 2, propagates as indicated by dashed lines in Fig. 2.
[0025]
A communication system using a reflector device 10 as described
above will bc described. As illustrated in Fig. 3, the conlmunication
25 system includes a first antenna 20 transmitting a linearly-polarized radio
wave to a reflector devicc 10 as illustrated in Figs. 1 and 2 and a second
antenna 30 receiving the linearly-polarized radio wave reflected by the
reflector device 10. The first antenna 20 and the second antenna 30 are
directional antennas such as parabolic antennas. In the reflector device
10
10, the plane of polarization of the linearly-polarized wave tilts in
accordance with the reflection angle. Specifically, the plane of
polarization of a linearly polarized radio wave reflected by the second
reflector plate 2a horizontally rotated while the inclination is kept at 45
5 degrees as illustrated in Fig. 2 rotates with respect to the radio wave
reflected by the second reflector plate 2 indicated by a solid line. The
first antenna 20 and/or the second antenna 30 is provided with a
polarization angle adjustment mechanism which adjusts the polarization
angle of a linearly polarized wave in accordance with an inclination of the
10 plane of polarization of the linearly-polarized wave in the polarizes device
10. An example of the polarization angle adjustment mechanism may
rotate the first antenna 20 about an axis of rotation 20a parallel to the
direction of maximum radiation of the mirror reflector of the antenna as
illustrated in Fig. 3 to adjust the polarization angle and, after the
15 adjustment, fix the first antenna 20. Similarly, the mechanism may rotate
the second antenna 30 about an axis of rotation 30a parallel to the direction
of maximum radiation of the mirror reflector of the antenna as illustrated
in Fig. 3 to adjust the polarization angle and, after the adjustment, fix the
second antenna 30. Such adjustment of the first antenna 20 and/or the
20 second antenna 30 allows the polarization angle of a radio wave to be
adjusted to enable communication.
[0026]
A communication method using a reflector device 10 as described
above will now be described. As illustrated in Fig. 3, the first reflector
25 plate 1 and the second reflector plate 2 of the reflector device 10 are
horizontally rotated to direct a radio wave to a first antenna 20 and a
second antenna 30. Then, a linearly-polarized radio wave is transmitted
from the first antcnna 20. In the reflector devicc 10, the radio wave is
reflected by the first reflector plate 1 in the vertical direction. The radio
11
wave reflected in the vertical direction is transmitted again horizontally at
the second reflector plate 2. In this process, the plane of polarization of
the radio wave rotates at the first reflector plate 1 and the second reflector
plate 2 in accordance with the direction of reflection. The radio wave
5 whose plane of polarization has rotated is received at the second antenna
30. By adjusting the polarization angle beforehand by the polarization
angle adjustment mechanism of at least one of the first antenna 20 and the
second antenna 30, good-quality communication can be provided. On the
other hand, when a radio wave i s transmitted from the second antenna 30
10 and is received at the first antenna 20, communication is provided by an
operation similar to the operation described above. The description of
the operation will be omitted.
[0027]
Design relating to the size of the first reflector plate 1 and the
15 second reflector plate 2 of the reflector device 10 of this exemplary
embodiment will be described. If the size D of a cross-section of the
reflector plates that is perpendicular to the direction of incidence a radio
wave is chosen to be equal to or greater than the first Fresnel radius,
coininunication with a propagation loss equivalent to a distance
20 approximately the same as the distance from the first antenna 20 to the
second antenna 30 via the reflector device 10 can be provided.
Specifically, let the distances from the reflector device to the antennas be
denoted by dl and d2, respectively, and the total distance be denoted by
d = d l + d2, then the propagation loss L [dB] can be obtained according to
25 the Friis transniission equation as:
L = +20 * loglo((4nd)lh) [dB]
where h is free space wavelength.
[0028]
When the size I> is smaller than the first Fresnel radius, each
12
reflector plate is approximately considered to be an antenna having
diameter D and equivalent gains Grefl [dBi] and Gref2 [dBi] are
Grefl = Gref2 = 20 * loglo(nDlh) [dBi]
Propagation losses from the reflector device 10 to the first antenna 20 and
5 the second antenna 30 can be written as
L1 = -20 '" loglo(nD/h) + 20 * loglo((4ndl)lh) [dB]
L2 = -20 * loglo(nDlh) + 20 * loglo((4nd2)lh) [dB]
and the total propagation loss i s
L = L1 + L2 [dB]
10 [0029]
For example, assume that the frequency is 60 GHz and dl = d2 =
200 m, then
L = approximately 120 [dB] for D = approximately 1.4 [m] and
L = 137 [dB] for D = approximately 0.3 [m].
15 In this way, the size of reflector plates used in this exemplary embodiment
call be chosen in accordance with required propagation loss values.
[0030]
According to this exemplary embodiment, the angle of inciderlce 0
of radio waves arriving at the reflector device 10 from the first antenna 20
20 or the second antenna 30 can be adjusted by rotating the first reflector
plate 1 or the second reflector plate 2. On the other hand, the angle of
incidence of radio waves at the first reflector plate 1 or the second
reflector plate 2 i s always 45 degrees. 'Thus, even when the angle of
incidence 0 is large, good-quality non-line-of-sight communication call be
25 provided witl~out increasing the area of the reflector plates.
[003 11
In this way, in a non-line-of-sight environment where an obstacle
40 exists on the path between the first antenna 20 and the second antenna
30, the reflector device 10 is illstalled and radio waves are reflected so that
13
the radio waves detour around the obstacle 40 to enable good-quality
point-to-point communication. With the reflector plates according to the
related techniques, communicatioi~ is possible only when the angle of
incidence is small, due to size constraints of the reflector plates. The
5 reflector device 10 of this exemplary embodiment, in contrast, is capable
of reflecting radio waves without using reflector plates with an increased
size even when the angle of incidence 0 is nearly 90 degrees.
[0032]
According to this exemplary embodiment, a good-quality radio
10 communication system can be implemented at low cost because a repeater
with two antennas coupled back to back as in Patent Literature1 (PTL1) is
not used. Furthermore, since the first antenna 20 and/or the second
antenna 30 is provided with a polarization angle adjustment mechanism
that adjusts the polarization angle of a linearly-polarized wave, the
15 polarization angle can be adjusted to allow polarization plane matching
even when the polarization angle rotates at the time of reflection in the
reflector device 10.
[003 31

20 A reflector device according to a second exemplary embodiment of
the present invention, a communication system using the reflector device
and a communicatioil method using the reflector device will be described
with reference to drawing. Elements similar to those of the first
exemplary embodiment are given the same reference numerals and detailed
25 description of those elements will be omitted. This exemplary
embodiment is a different embodin~enth at uses a reflector device
according to the first exemplary embodiment.
[0034]
A conllnunication system using such a reflector device 10 will be
14
described. As illustrated in Fig. 4, the communication system includes a
first antenna 50 which transmits a circularly polarized radio wave to a
reflector device 10 illustrated in Figs. 1 and 2, a second antenna 60 which
receives a circularly polarized radio wave reflected at the reflector device
5 10. The first antenna 50 and the second antenna 60 are directional
antennas such as parabolic antennas. The directional antennas in this
exemplary embodiment are circularly polarized antennas.
[0035]
A communication method using a reflector device 10 as the one
10 described above will be described. As illustrated in Fig. 4, a first
reflector plate and a second reflector plate of the reflector device 10 are
horizontally rotated so as to direct radio waves to the first antenna 50 and
the second antenna 60, respectively. Then, a circularly polarized wave,
for example a right-handed circularly polarized (RHCP) radio wave is
15 transmitted from the first antenna 50. In the reflector device 10, the
radio wave is reflected by the first reflector plate 1 in the vertical direction.
The radio wavc reflected in the vertical direction is transmitted in the
horizontal direction again at the second reflector plate 2. On the other
hand, when a radio wavc is transmitted from the second antenna 60 and
20 received at the first antenna 50, conlmunication is provided by an operation
similar to the operation described above. The description of the
operation will be omitted.
[0036]
According to this exelnplary embodiment, as in the first exemplary
25 embodiment, the angle of incidence 0 of radio waves arriving at the
reflector device 10 from the first antenna 50 or the second antenna 60 can
be adjusted by rotating the first reflector plate 1 or the second reflector
plate 2. On the other hand, the angle of incidence of radio wavcs at the
first reflector plate 1 or the second reflector plate 2 is always 45 degrees.
15
Thus, even when the angle of incidence 0 is large, good-quality
non-line-of-sight communication can be provided without increasing the
area of the reflector plates.
[0037]
5 In this way, in a non-line-of-sight environment where an obstacle
40 exists on the path between the first antenna 50 and the second antenna
60, the reflector device 10 is installed and radio waves are reflected so that
the radio waves detour around the obstacle 40 to enable good-quality
point-to-point communication. With the reflector plates according to the
10 related techniques, communication is possible only when the angle of
incidence i s small, due to size constraints of the reflector plates. In
contrast, the reflector device 10 of this exemplary embodiment, like the
reflector device 10 of the first embodiment, i s capable of reflecting radio
waves without using reflector plates with an increased size even when the
15 angle of incidence 8 is nearly 90 degrees.
[003 81
According to this exemplary embodiment, a good-quality radio
comn~unications ystem can be implemented at low cost because a repeater
with two antennas coupled back to back as in Patent Literature 1 (PTL1) is
20 not used.
100391
Moreover, a circularly polarized wave is used for a polarized wave
of thc directional antennas in this exemplary embodiment. In the first
embodiment, the polarization angle adjustment mechanisms of the
25 directional antennas are used to adjust polarization because the plane of
polarizatioil of polarized waves changes in accordance with the reflection
angle of the radio waves in the reflector device 10. On the other hand,
according to the second exemplary embodiment, the need for adjustment of
polarization at the antennas can be eliminated because circular polarized
wave is used.
[0040]
While preferred exemplary embodiments have been described with
reference t,o the drawings, the present invention is not limited to these
5 exemplary embodiments. The novel technical features of the
embodiments described above are summarized below. However, the
present invention is not necessarily limited to these features.
(Supplementary Note 1) A reflector device including a first reflector
plate and a second reflector plate to each of which a reflective surface is
10 attached at a predetermined inclination angle to an axis of rotation,
wherein the first reflector plate and the second reflector plate are
positioned to face one another, and at least one of the first reflector plate
and the second reflector plate is rotatable about the axis of rotation.
(Supplementary Note 2) The reflector device according to
15 Supplementary Note 1, further including a first support fixing the first
reflector plate at the predetermined inclination angle, a second support
fixing the second reflector plate at the predetermined inclination angle, a
radome housing the first and second reflcctor plates and the first and
second supports.
20 (Supplementary Note 3) The reflector device according to
Supplementary Note 1, wherein the reflective surface of each of the first
reflector plate and the second reflector plate is substantially elliptical in
shape.
(Supplementary Note 4) The reflector device according to any one of
25 Supplementary Notes 1 to 3, wherein the shape of each of the first reflector
plate and the sccond reflector plate that is projected on a plane parallel to
the axis of rotation is substantially circular.
(Supplementary Note 5 ) The reflector device according to any one of
Supplementary Notes 1 to 4, wherein the predetermined angle is
17
approximately 45 degrees.
(Supplementary Note 6) A communication system using a reflector
device according to any one of Supplementary Notes 1 to 5, the
communication system including a first antenna transmitting a radio wave
5 to the reflective surface of the first reflector plate of the reflector device
and a second antenna receiving the radio wave reflected by the first
reflector plate of the reflector device and then reflected by the reflective
surface of the second reflector plate.
(Supplementary Note 7) The communication system according to
10 Supplementary Note 6, wherein the first antenna transmits a linearly
polarized radio wave and at least one of the first antenna and the second
antenna includes a polarization angle adjustment mechanism adjusting a
polarization angle of linear polarization.
(Supplementary Note 8) The communication system according to
15 Supplementary Note 6, wherein the radio wave transmitted by the first
antenna is a circularly polarized wave and the radio wave received by the
second antenna is a circularly polarized wave.
(Supplementary Note 9) A communication method using a reflector
device reflecting a horizontally iilcident wave in a vertical direction as a
20 first reflected wave, reflecting the first reflected wave in a horizontal
direction as a second reflected wave, and emitting the second reflected
wave in a direction that is not parallel to the incident wave.
(Supplementary Note 10) A communication method using:
a reflector device including a first reflector plate and a second
25 reflector plate to each of which a reflective surface is attached at a
predetermined inclination angle to an axis of rotation, wherein the first
reflector plate and the second reflector plate are positioned to face one
another, and at least one of the first reflector plate and the second reflector
plate is rotatable about the axis of rotation;
18
a first antenna transmitting a radio wave to the reflective surface of
the first reflector plate of the reflector device; and
a second antenna receiving the radio wave reflected by the first
reflector plate of the reflector device and then reflected by the reflective
5 surface of the second reflector plate;
wherein at least one of the first reflector plate and the second
reflector plate of the reflector device is horizontally rotated so as to direct
radio waves to the first antenna and the second antenna, a radio wave i s
transmitted from the first antenna to the reflective surface of the first
10 reflector plate, the radio wave reflected by the first reflector plate of the
reflector device and further reflected by the reflective surface of the
second reflector plate is received by the second antenna.
(Supplementary Note 11) The communication method according to
Supplementary Note 10, wherein the first antenna tra~lsmits a linearly
15 polarized radio wave and at least one of the first antenna and the second
antenna includes a polarization angle adjustment mechanism adjusting a
polarization angle of linear polarization.
(Supplementary Note 12) The cominunication rnetl~od according to
Supplementary Note 10, wherein the radio wave transn~itted by the first
20 antenna i s a circularly polarized wave and the radio wave received by the
second antenna is a circularly polarized wave.
[0041]
It would be understood that the present invention is not limited to
the exemplary elnbodirnents described above and various modifications are
25 possible within the scope of the prcsel~ti nvention defined in the claims and
it is needless to say that those modifications also fall within the scope of
the prcsent invention.
100421
This application is based upon and clainls the benefit of priority
19
from Japanese patent application No. 2012-204376, filed on September 18,
2012, the disclosure of which is incorporated herein in its entirety by
reference.
[Reference Signs List]
5 [0043]
1 First reflector plate
2 Second reflector plate
3 First support
4 Second support
10 5 Radome
10 Reflector device
20, 50 First antenna
30, 60 Second antenna
20a, 30a Axis of rotation
15 40 Obstacle

WE CLAIM:
[Claim 1]
A reflector device con~prisinga first reflector plate and a second
reflector plate to each of which a reflective surface is attached at a
5 predetermined inclination angle to an axis of rotation, wherein
the first reflector plate and the second reflector plate are positioned
to face one another, and at least one of the first reflector plate and the
second reflector plate is rotatable about the axis of rotation.
[Claim 2] The reflector device according to claim 1, further
10 comprising a first support fixing the first reflector plate at the
predetermined inclination angle, a second support fixing the second
reflector plate at the predetermined inclination angle, a radome housing the
first and second reflector plates and the first and second supports.
[Claim 3] The reflector device according to claim 1, wherein the
I5 reflective surface of each of the first reflector plate and the second
reflector plate is substantially elliptical in shape.
[Claim 4] The reflector device according to any one of claims 1 to 3,
wherein the shape of each of the first reflector plate and the second
reflector plate that is projected on a plane parallel to the axis of rotation is
20 substantially circular.
[Claim 5] The reflector device according to any one of claims 1 to 4,
wherein the predetermined angle is approximately 45 degrees.
[Claim 6] A cornmunicatioll system using a reflector device according
to any onc of claims 1 to 5 , the communication system comprising a first
25 antenna transmitting a radio wave to the reflective surface of the first
reflector plate of the reflector device and a second antenna receiving the
radio wave reflected by the first reflector plate of the reflector devicc and
then reflected by the reflective surface of thc second reflector plate.
[Claim 7] The communication system according to claim 6, wherein
2 1
the first antenna transmits a linearly polarized radio wave and at least one
of the first antenna and the second antenna comprises a polarization angle
adjustment mechanism adjusting a polarization angle of linear
polarization.
5 [Claim 8] The communication system according to claim 6, wherein
the radio wave transmitted by the first antenna is a circularly polarized
wave and the radio wave received by the second antenna is a circularly
polarized wave.
[Claim 9] A communication method using a reflector device reflecting
10 a horizontally incident wave in a vertical direction as a first reflected wave,
reflecting the first reflected wave in a horizontal direction as a second
reflected wave, and emitting the second reflected wave in a direction that
is not parallel to the incident wave.
[Claim 10] A communication method using:
15 a reflector device co~nprisinga first reflector plate and a second
reflector plate to each of which a reflective surface is attached at a
predetermined inclination angle to an axis of rotation, wherein the first
reflector plate and the second reflector plate are positioned to face one
another, and at least one of the first reflector plate and the second reflector
20 plate is rotatable about the axis of rotation;
a first antenna transmitting a radio wave to the reflective surface of
the first reflector plate of the reflector device; and
a second antenna receiving the radio wave reflected by the first
reflector plate of the reflector device and then reflected by the reflective
25 surface of the second reflector plate;
wherein at least one of the first reflector plate and the second
reflector plate of the reflector device is horizontally rotated to direct a
radio wave to the first antenna and the second antenna, a radio wavc is
traiisinitted fro111 the first antenna to the reSlective surface of the first
22
reflector plate, the radio wave reflected by the first reflector plate of the
reflector device and further reflected by the reflective surface of the
second reflector plate is received by the second antenna.