1. An antenna device of a single beam scheme, comprising: a reflector configured to form an offset antenna with a portion of a rotational 5 paraboloid being cut out; and a primary radiator configured to radiate a beam having an elliptical cone shape to an aperture plane of the reflector, wherein a contour of the aperture plane of the reflector is formed along an isolux line of the beam having the elliptical cone shape radiated from the primary radiator.

2. An antenna device of a single beam scheme, comprising: a reflector configured to form an offset antenna with a portion of a rotational paraboloid being cut out; a sub-reflector configured to radiate a beam having an elliptical cone shape to an 15 aperture plane of the reflector; and a primary radiator configured to radiate a beam having any shape to the sub-reflector, wherein a contour of the aperture plane of the reflector is formed along an isolux line of the beam having an elliptical cone shape radiated from the sub-reflector. 20

3. The antenna device according to claim 2, wherein: the primary radiator radiates the beam having an elliptical cone shape to the sub-reflector, and a contour of the aperture plane of the sub-reflector is formed along an isolux line 25 of the beam having an elliptical cone shape radiated from the primary radiator.

4. The antenna device according to any one of claims 1 to 3, wherein the contour of the aperture plane of the reflector is formed along an isolux line of - 12 dB when an illuminance of a central portion of the beam having an elliptical cone shape 5 radiated from the primary radiator is 0 dB.

5. The antenna device according to any one of claims 1 to 4, wherein: when a contour formed in the aperture plane of the reflector along the isolux line of the beam having an elliptical cone shape radiated from the primary radiator is a first 10 contour, and a virtual elliptical contour formed to be perpendicular to an axis of the beam incident on the aperture plane of the reflector is a second contour, a space in which the first contour protrudes from the second contour is a space which compensates for a loss due to spillover of the reflector. 15 6. The antenna device according to claim 5, wherein a space in which the second contour protrudes from the first contour is a space which compensates for degradation of illuminance efficiency of the reflector.

7. 'l'he antenna device according to claim 5 or 6, wherein, in each of an ellipse 20 of the first contour and an ellipse of the second contour, a ratio of a horizontal width and a vertical width is substantially 2: 1.

8. The antenna device according to any one of claims 1 to 7, wherein a central axis of the beam having an elliptical cone shape radiated from the primary radiator to the 25 aperture plane of the reflector forms a predetermined angle with a rotational axis of the rotational paraboloid.

9. The antenna device according to any one of claims 1 to 8, wl~ereinth e beam having an elliptical cone shape radiated from the primary radiator to the aperture plane of 5 the reflector exhibits an ideal Gaussian distribution characteristic.

10. The antenna device according to any one of claims I to 9, being used for a point-to-point comlnunication system including a mobile backhaul. 10 Dated this 17'" day of February 2014 Of Anand and Anand Advocates Agent for the applicant 19 ABSTRACT ANTENNA DEVICE An antenna device includes a reflector which forms an offset antenna with a 5 portion of a rotational paraboloid being cut out, and a primary radiator which radiates a beam having an elliptical cone shape to an aperture plane of the reflector. A reflector contour of the aperture plane of the reflector is formed in an elliptical shape along an isolux line of an elliptical beam radiated froin the primary radiator. Accordingly, a loss due to spillover of the reflector is compensated for in a space in which the reflector 10 contour of the present embodiment protrudes from a general reflector contour having a virtual elliptical shape formed to be perpendicular to an axis of a beam incident on an aperture plane of the reflector. In a space in which the general reflector contour protrudes from the reflector contour of the present embodiment, degradation of illuminance efficiency of the reflector is compensated.

DESCRIPTION
ANTENNA DEVICE
TECHNICAL FIELD
[OOO 11
The present invention relates to an antenna device used for a point-to-point
communication system such as a mobile backhaul, and more particularly, to an antenna
device of a single beam scheme which radiates a beam in one direction from one antenna.
BACKGROUND ART
[00021
An antenna device such as a parabolic antenna is widely used for, for example, a
mobile backhaul known as an RAN (Radio Access Network) which connects a wireless
base station with a trunk network. Pal-titularly, in the mobile backhaul, an a~ltelllla
15 device of a single beam scheme which radiates a beam in one direction using a reflector
and one primary radiator is widely used.
An offset parabolic antenna configured to reduce probability of reception of
unnecessary radio waves only using a portion of the reflector of the parabolic antenna is
often used as such an antenna device of a single beam scheme.
20 [0003]
For example, technology of an offset parabolic reflector adapted not to receive
unnecessary radio waves by reducing an aperture plane of a reflector is disclosed in
Patent Document 1 as related technology for an antenna device including a reflector
antenna of a single beam scheme. According to this technology, in the offset parabolic
25 reflector formed in a shape in which a portion of a rotational parabolic reflector is cut, the
3
reflector is formed so that a shape when a peripheral postion is viewed from a focus
position of the offset parabolic reflector is substantially circular. In other words, wliile
spillover (leakage) in a long axis direction increases in an elliptical reflector, it is possible
to suppress the spillover to be low and achieve uniformity of an irradiation level in the
5 peripheral portion of the reflector by causing the shape when the peripheral portion is
viewed from the focus position of the reflector to be circular. As a result, it is possible
to improve irradiation efficiency of the reflector.
[0004]
Further, for example, technology for a method of realizing a low side lobe
10 characteristic of an offset elliptical beam antenna has been reported in Non-Patent
Document 1 as related technology of the offset parabolic reflector.
[0005]
Further, for example, technology for causing a shape of a contour of a reflector
to be a shape along a contour line corresponding to an aperture plane phase deviation
15 caused by a mirror surface aberration in an antenna of a multi-beam scheme whicl~
radiates a beam in a plurality of directions from one antenna is disclosed as another
related technology in Patent Document 2. According to this technology, it is possible to
suppress deterioration of a beam directional characteristic, increase of a side lobe (leaked
electromagnetic: waves), and reduction of an antenna gain caused by a mirror surface
20 aberration (i.e., a path difference of radio waves due to a difference in reflection position
in a mirror surface) by forming the contour of the reflector along the contour line
obtained by the mirror surface aberratioii.
[Documents of the prior art]
[Patent Documents]
2.5 [0006]
4
[Patent Document 1] Japanese Examined Patent Application Publication No. 2592646
[Patent Document 21 Japanese Unexamined Patent Application Publication, First
Publication No. H9-5 121 1
mon-Patent Document]
5 [0007]
won-Patent Document 11 Katsuhiko Aokio et al., "Method of Realizing Low Side Lobe
Chai-acteristic of Offset Elliptical Beam Antenna," B-11, Communication 11-Wireless
Communication and Wireless Application J81-B-2(8), 789-796, 1998-08-25, The
Institute of Electronics, Information and Communication Engineers.
DISCLOSURE OF INVENTION
[Problems to be solved by the invention]
[OOOS]
Generally, in a reflector antenna (antenna device) including a reflector and a
15 primary radiator, if a width of the beam of the primary radiator is wide, an illuminance
distribution of the aperture plane of the reflector approaches a uniform distribution state
and irradiation efficiency is improved. However, there is a disadvantage that, since the
width of the beam is wide, a portion of the beam does not hit the reflector and power
wliicli is spillover (leakage) increases, which is a loss. On the other hand, if the width
20 of the bcam of the primary radiator is narrow, the loss due to the spillover can be reduced,
but irradiation efficiency may be degraded since the illuminance distribution in the
aperture plane of the reflector is not uniform. Therefore, it is necessary to appropriately
design the width of the beam irradiated from the primary radiator so that a trade-off
relationship between the irradiation efficiency and the loss due to the spillover in the
25 aperture plane of the reflector is optimized, in order to maximize the irradiation
efficiency for the antenna device.
[0009]
For example, when a reflector including an ideal rotational paraboloid and a
primary radiator radiating a beam exhibiting an ideal Gaussian distribution characteristic
5 (normal distribution characteristic) are used, the width (thickness) of the beam of the
priinary radiator is determined so that an illuminance of the contour portion relative to
illuminance (0 dB) of a center of the reflector is generally about -12 dB. In this case,
the trade-off relationship between the spillover of the reflector and the irradiation
efficiency of the aperture plane of the reflector is optimized, and the irradiation efficiency
10 for the antenna device exhibits a maximum value.
[OOl O]
However, since the shape of an aperture plane in the general offset antenna with
a reduced side lobe characteristic is an elliptical shape, illuminance strength fro111 the
primary radiator in the contour of the reflector does not have a constant value, and
15 unevenness (strength and weakness) occurs. Therefore, it is not possible to optimize the
trade-off relationship between the loss due to the spillover and enhancement of the
irradiation efficiency even if the width of the beam of the primary radiator is varied. 111
other words, there is a problem in that it is difficult to maximize the irradiation efficiency
for the anterma device.
20 [OOll]
Further, there is another problem in that the loss due to the spillover is still large
since the illuminance in the contour portion of the elliptical aperture plane is not constant
even when the illuminance in the contour pol-tion of the reflector is set to be low, in order
to realize the low side lobe characteristic for reducing leakage of electromagnetic waves
25 fiom the reflector.
6
[OO 1 21
Further, it is necessary to have an elliptical shape in which the horizontal width
of the reflector is much greater than its vertical width in order to realize a low side lobe
characteristic of a horizontal plane. However, in the technology of Patent Document 1
5 described above, it is not possible to realize the low side lobe characteristic of the
horizontal plane since the reflector is formed so that the shape when the peripheral
portion is viewed from the focus position of the offset parabolic reflector becomes
substantially circular.
In other words, in the technology of Patent Document 1, it is not possible to
10 realize the superiority of the elliptical reflector antenna in w11ich the horizontal width and
the vertical width of the reflector are greatly different.
[00 131
Further, the technology of Non-Patent Document 1 realizes the low side lobe
characteristic by causing the reflector to be elliptical, but optimal illuininance efficiency
15 cannot be obtained in this technology since the elliptical shape of the reflector does not
inatch an isolux line of an elliptical beam.
[00 1 41
Further, in the technology of Patent Document 2, in the antenna device of a
multi-beam scheme in which a plurality of primary radiators share one reflector and
20 radiate a beam in a plurality of directions, increase of the side lobe or the like is
suppressed by causing the contour of the reflector to have a shape along the contour line
corresponding to the aperture plane phase deviation caused by the ~nirrors urface
aberration. However, the mirror surface aberration is caused by a path difference being
generated in radio waves due to a direction of the beam since the plurality of beams share
25 the same reflector in the antenna device of a multi-beam scheme. Therefore, such a
7
mirror surface aberration is specific to the antenna device of a multi-beam scheme, and is
not theoretically generated in an antenna device of a single beam scheme. Therefore,
even when the technology of Patent Document 2 is known, the technology cannot be
applied to technology for enhancing the irradiation efficiency, the spillover, the side lobe
5 characteristic, and the like in the antenna device of a single beam scheme.
[OO 1 51
The present invention has been made in view of such circumstances and an
object of the present invention is to provide an antenna device of a single beam scheme
which has small spillover due to good irradiation efficiency of a reflector and an
10 excellent low side lobe characteristic.
[Means for solving the problem]
[00 1 61
In order to achieve the object described above, an antenna device according to
the present invention is an antenna device of a single beam scheme, including: a reflector
15 which forms an offset antenna with a portion of a rotational paraboloid being cut out; and
a primary radiator which radiates a beam having an elliptical cone shape to an aperture
plane of the reflector, wherein a contour of the apeiture plane of the reflector is formed
along an isolux line of the beam having the elliptical cone shape radiated from the
primary radiator.
20 [0017]
Further, an antenna device according to the present invention is an antenna
device of a single beam scheme, including: a reflector which forms an offset ai~tenna
with a portion of a rotational paraboloid being cut out; a sub-reflector which radiates a
beam having an elliptical cone shape to an aperture plane of the reflector; and a primary
25 radiator which radiates a beam having any shape to the sub-reflector, wherein a contour
8
of the aperture plane of the reflector is formed along an isolux line of the beam having an
elliptical cone shape radiated from the sub-reflector.
[Effects of the Invention]
[00 1 81
5 According to the antenna device according to the present invention, since the
contour of the reflector is formed along the isolux line of the elliptical beam radiated
fro111 the primary radiator, it is possible to optimize a trade-off relationship of the
spillover and the irradiation efficiency. As a result, it is possible to achieve reduction of
a loss due to spillover, improvement of irradiation efficiency, enhancement of a side lobe
10 characteristic, and the like and to improve antenna performance.
BRIEF DESCRIPTON OF THE DRAWINGS
[00 191
FIG. 1 is a diagram illustrating a schematic configuration and an isolux line of an
15 antenna device of a single beam scheme according to a first embodiment of the present
invention.
FIG. 2 is an illustrative diagram of the antenna device of a single beam scheme
according to the first embodiment of the present invention.
FIG, 3 is an iIIustrative diagram of an antenna device of a single beam scheme
20 according to a second embodiment of the present invention.
EMBODIMENS FOR CARRYING OUT THE INVENTION
[0020]
[Outline]
25 The antenna device of the present invention is an antenna device of a single
9
bean1 scheme including one reflector and one primary radiator and is characterized in that
a contour of the reflector is determined so that an illuminance of a beam from the
primary radiator has a constant value along a contour of the reflector. In other words, in
the antenna device of the present invention, the cotltour of the reflector is determined
5 along a contour line (i.e., an isolux line) of an amplitude distribution of an illulniiiance of
a beam radiated from the primary radiator.
[002 1 ]
[First embodiment]
FIG. 1 is a diagram illustrating a schematic configuration and an isolux line of an
10 antenna device of a single beam scheme according to a first embodiment of the present
invention. The antenna device 1 includes a reflector 2 and a pri~naryra diator 3, as
illustrated in FIG. 1. Further, a mirror surface of the reflector 2 is a portion of a
rotational paraboloid. Further, FIG. 1 illustrates a parabola in which an isolux line L on
the rotational paraboloid is -6 dB, -9 dB, -12 dB, or -1 5 dB with an illuminance in a
15 maximum direction (a center of an ellipse) of the elliptical beam 4 of the priinary radiator
3 being 0 dB.
[0022]
The primary radiator 3 is arranged in such a manner that a phase center of the
primary radiator 3 matches a focus of the rotational paraboloid. Further, a ceiltral axis
20 of the elliptical beam 4 of the primary radiator 3 forms a predetermined angle (e.g., 50
degrees) with a rotation axis of the rotational paraboloid. In this case, the illumination
of the elliptical beam 4 radiated from the primary radiator 3 to the reflector 2 determines
a shape of a reflector contour 2a of the present embodiment along a contour line (isolux
line) which is the same value on the mirror surface of the reflector 2. For example, the
25 isolux line in which the illumination is -12 dB is the reflector contour 2a of the present
embodiment, as illustrated in FIG. 1.
[0023]
Ful-ther, in this antenna device 1, the reflector 2 has a long elliptical shape whose
horizontal width is much greater than its vertical width in order to realize a low side lobe
5 characteristic of the horizontal plane. Generally, as the horizontal width of the reflector
2 is great, a relative level of the side lobe becomes low, and specifically, a ratio of the
horizontal width and the vertical width is 2: 1. Further, a reason for a non-circular beam
is that, when the vertical width increases similarly to the horizontal width, a swept area
of the antenna device 1 increases and a structural limitation at the time of installation of
10 the antenna device 1 increases. Further, in this type of antenna device 1, the low side
lobe is unnecessary for a vel-tical plane (a direction of a vertical width). Therefore, the
beam radiated from the primary radiator 3 is the elliptical beam 4 which is long in a
horizontal direction and has a substantially elliptical shape in order to suppoi-t the
reflector 2 having a great horizontal width.
15 [0024]
Further, a reflector contour 11 of a general offset parabolic antenna is illustrated
in FIG. I. The general reflector contour 11 determines a shape of the corresponding
reflector 2 so that a shape of an aperture plane (a virtual plane perpendicular to an axis of
a beam from the reflector 2) is elliptical. However, in the general offset parabolic
20 antenna, the elliptical reflector contour 11 is not related to an isolux line at all.
[0025]
In other words, in the elliptical offset type reflector having the horizontal width
greater than the vertical width, a general antenna device reduces the irradiation efficiency
since a deviation of the elliptical shape is large as illustrated in FIG. 1 between the
25 general reflector contour 11 and the reflector contour 2a of the present embodiment.
1 I
[0026]
On the other hand, in the case of the antenna device 1 of the present embodiment,
a loss due to spillover is the sum of powers of portions with which the reflector 2 is not
irradiated, of the elliptical bean1 4 of the primary radiator 3, but in this case, the sum of
5 the powers is equal to or less than a certain level (-12 dB). Generally, the loss due to
the spillover depends on a size of power radiated to the outside of the reflector coiltour 2a
of the present embodiment. Therefore, it is effective to reduce the illumination (the
isolux line) of the reflector contour 2a of the present embodiment in order to reduce the
loss due to the spillover.
10 [0027]
Meanwhile, the power of the elliptical beam 4 with which the reflector 2 is
irradiated from the primary radiator 3 is a sum of powers equal to or higher than a certain
level (-12 dB). Generally, it is effective to increase the illumination of the reflector
contour 2a in order to enhance the irradiation efficiency of the reflector 2. Therefore, it
15 is possible to maximize the irradiation efficiency of the antenna device 1 since it is
possible to efficiently optimize the trade-off relationship of the loss due to the spillover
and the irradiation efficiency of the reflector 2 wheil the illumination of the reflector
contour 2a is at a certain level.
[0028]
20 Further, since the reflector contour 2a of the present embodiment and the general
reflector contour 11 are displayed side by side in FIG, 1, improvements with regard to the
spillover or the irradiation efficiency by the present embodiment can be confirn~ed. In
other words, spaces S 1 and S2 in which the reflector contour 2a of the present
embodiment protrudes from the general reflector contour 11 are spaces in which the
25 antenna device 1 of the present embodiment contributes to the loss due to the spillover
12
generated in a conventional antenna device. Further, spaces S3 and S4in which the
general reflector contour 11 protrudes from the reflector contour 2a of the present
embodiment are spaces in which the antenna device 1 of the present embodin~ent
contributes to reduction of the irradiation efficiency generated in the conventional
5 antenna device.
[0029]
FIG 2 is an illustrative diagram of the antenna device of a single beam scheme
according to the first embodiment of the present invention. In other words, the reflector
2 is the offset antenna in which a portion of the rotational paraboloid P is cut out,
10 receives the beam (elliptical beam) in an elliptical cone shape from the primary radiator 3
in the focus position of the reflector 2, and reflects a beam of a parallel line froin the
reflector 2. The shape of the contour of the reflector 2 is a locus of the isolux line when
the reflector 2 is irradiated with the elliptical beam from the primary radiator 3, as
illustrated in FIG. 1. For example, the shape of the contour of the reflector 2 is a locus
15 of the isolux line of -12 dB when the center of the elliptical beam has 0 dB.
Accordingly, improvements with regard to the spillover, the irradiation efficiency, the
low side lobe characteristic, and the like are possible in cornparison with the general
antenna device.
[UU3U]
20 [Second embodiment]
FIG. 3 is an illustrative diagram of an antenna device of a single beam scheme
according to a second embodiment of the present invention. In the antenna device of
the second embodiment, the shape of the contour of the reflector 2 beco~nesth e locus of
the isolux line, as in FIG. 1. Further, the second embodiment is the same as the first
25 embodiment in that the reflector 2 is the offset antenna in which a portion of a rotatioi~al
13
paraboloid P is cut out. A characteristic of the antenna device of the second
embodiment is that the primary radiator 3 illustrated in FIG. 2 is replaced with a priinary
radiator system including a primary radiator 6 and a sub-reflector 7 as illustrated in FIG.
3.
5 [0031]
In other words, in the primary radiator system, when the sub-reflector 7 is
irradiated with a beam having any shape from the primary radiator 6, the reflector 2 is
irradiated with a beam (elliptical beam) having an elliptical cone shape froin the
sub-reflector 7. In this case, the shape of the contour of the reflector 2 is set so that an
10 illuminance in the contour of the reflector 2 of the elliptical beam irradiated horn the
sub-reflector 7 is constant. In the antenna device of the second embodiment,
improvements with regard to the spillover, the irradiation efficiency, the low side lobe
characteristic, and the like are possible in comparison with the general antenna device,
similar to the first embodiment.
15 [0032]
[Third embodiment]
In an antenna device according to a third ernbodimel~ot f the present invention,
the shape of the sub-reflector 7 of the second embodiment illustrated in FIG. 3 is
determined by an isolux line in which an illuminance on the sub-reflector 7 due to the
20 beam (elliptical beam) having an elliptical cone shape radiated from the primary radiator
6 is constant. In other words, the contour of the sub-reflector is formed along the isolux
line of the elliptical beam, similar to the contour of the reflector 2. Accordingly, it is
possible to maximize efficiency of the entire antenna device since mitigation of the loss
due to the spillover in the sub-reflector 7 and optimal design of the irradiation efficiency
25 can be realized, in addition to the effects of the first embodiment and the second
embodiment.
[003 31
As described above, according to the antenna devices according to the
embodiments of the present invention, since a design for optimizing the trade-off
5 relationship between the spillover and the irradiation efficiency can be performed, it is
possible to improve efficiency of the entire antenna in comparison with a general antenna
device. It is also possible to enhance the side lobe characteristic in a horizo~ltal
direction without increasing a load applied to the antenna device during a typhoon. It is
also possible to achieve further miniaturization of the reflector since the efficiency of the
10 antenna device is improved. Further, in the antenna device using a double reflector, it is
possible to improve efficiency of the sub-reflector.
[0034]
While the embodiments of the antenna device according to the present invention
have been described in detail with reference to the drawings, the concrete configuration
15 of the present invention is not limited to the content of the embodiments described above,
and a change in design without departing from the scope and spirit of the present
invention is included in the present invention.
[003 51
Priority 1s claimed on Japanese Patent Application No. 20 1 1 - 184904, filed
20 August 26, 201 1, the content of which is incorporated herein by reference.
INDUSTRIAL APPLICABILITY
[0036]
The antenna device of the present invention can be effectively used for a
point-to-point communication system such as a mobile backhaul as a parabolic antenna
25 or an offset parabolic antenna of a single beam scheme.
15
[Description of Reference Symbols]
[0037]
1 antenna device
2 reflector
5 2a reflector contour of the present embodiment
3 first radiator
4 elliptical beam
6 first radiator
7 sub-reflector
10 1 1 general reflector contour
S1 space contributing to loss due to spillover
S2 space contributing to loss due to spillover
S3 space contributing to degradation of irradiation efficiency
S4 space contributing to degradation of irradiation efficiency
15 L isolux line on rotational paraboloid
P rotational paraboloid
WE CLAIM:
1. An antenna device of a single beam scheme, comprising:
a reflector configured to form an offset antenna with a portion of a rotational
5 paraboloid being cut out; and
a primary radiator configured to radiate a beam having an elliptical cone shape
to an aperture plane of the reflector,
wherein a contour of the aperture plane of the reflector is formed along an isolux
line of the beam having the elliptical cone shape radiated from the primary radiator.
2. An antenna device of a single beam scheme, comprising:
a reflector configured to form an offset antenna with a portion of a rotational
paraboloid being cut out;
a sub-reflector configured to radiate a beam having an elliptical cone shape to an
15 aperture plane of the reflector; and
a primary radiator configured to radiate a beam having any shape to the
sub-reflector,
wherein a contour of the aperture plane of the reflector is formed along an isolux
line of the beam having an elliptical cone shape radiated from the sub-reflector.
20
3. The antenna device according to claim 2, wherein:
the primary radiator radiates the beam having an elliptical cone shape to the
sub-reflector, and
a contour of the aperture plane of the sub-reflector is formed along an isolux line
25 of the beam having an elliptical cone shape radiated from the primary radiator.
4. The antenna device according to any one of claims 1 to 3, wherein the
contour of the aperture plane of the reflector is formed along an isolux line of - 12 dB
when an illuminance of a central portion of the beam having an elliptical cone shape
5 radiated from the primary radiator is 0 dB.
5. The antenna device according to any one of claims 1 to 4, wherein:
when a contour formed in the aperture plane of the reflector along the isolux line
of the beam having an elliptical cone shape radiated from the primary radiator is a first
10 contour, and a virtual elliptical contour formed to be perpendicular to an axis of the beam
incident on the aperture plane of the reflector is a second contour,
a space in which the first contour protrudes from the second contour is a space
which compensates for a loss due to spillover of the reflector.
15 6. The antenna device according to claim 5, wherein a space in which the
second contour protrudes from the first contour is a space which compensates for
degradation of illuminance efficiency of the reflector.
7. 'l'he antenna device according to claim 5 or 6, wherein, in each of an ellipse
20 of the first contour and an ellipse of the second contour, a ratio of a horizontal width and
a vertical width is substantially 2: 1.
8. The antenna device according to any one of claims 1 to 7, wherein a central
axis of the beam having an elliptical cone shape radiated from the primary radiator to the
25 aperture plane of the reflector forms a predetermined angle with a rotational axis of the
rotational paraboloid.
9. The antenna device according to any one of claims 1 to 8, wl~ereinth e beam
having an elliptical cone shape radiated from the primary radiator to the aperture plane of
5 the reflector exhibits an ideal Gaussian distribution characteristic.
10. The antenna device according to any one of claims I to 9, being used for a
point-to-point comlnunication system including a mobile backhaul.
10 Dated this 17'" day of February 2014
Of Anand and Anand Advocates
Agent for the applicant
19
ABSTRACT
ANTENNA DEVICE
An antenna device includes a reflector which forms an offset antenna with a
5 portion of a rotational paraboloid being cut out, and a primary radiator which radiates a
beam having an elliptical cone shape to an aperture plane of the reflector. A reflector
contour of the aperture plane of the reflector is formed in an elliptical shape along an
isolux line of an elliptical beam radiated froin the primary radiator. Accordingly, a loss
due to spillover of the reflector is compensated for in a space in which the reflector
10 contour of the present embodiment protrudes from a general reflector contour having a
virtual elliptical shape formed to be perpendicular to an axis of a beam incident on an
aperture plane of the reflector. In a space in which the general reflector contour
protrudes from the reflector contour of the present embodiment, degradation of
illuminance efficiency of the reflector is compensated.