JP2010034754A - Lens antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive lens antenna apparatus that achieves high sensitivity reception. <P>SOLUTION: A lens antenna apparatus includes a hemispherical lens antenna 5 where hemispheric lenses 55 obtained by dividing a single spherical lens for converging a radio wave beam substantially equally into two are mounted on a radio wave reflector 54, an angle adjustment means that adjusts the angle of reflection of a radio wave beam for the radio wave reflector 54 by controlling the direction of the hemispheric lens antenna 5 mechanically, and an antenna element 6 which receives the radio wave beam converged by the hemispheric lenses 55, wherein the antenna element 6 consists of a horn antenna 61 into which a dielectric insert 63 is inserted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens antenna device for mobile communication that is mounted on a mobile body such as a ship or an airplane and receives radio waves from an artificial satellite or a ground station.

  Conventionally, by using a spherical lens capable of focusing a radio wave beam, an antenna element is arranged at a predetermined position on the hemispherical surface of the spherical lens, and the directivity of the antenna element is aligned with the central direction of the spherical lens, thereby obtaining a predetermined direction. A lens antenna device for forming a radio wave beam has been proposed. This lens antenna device can direct a radio wave beam in a desired direction simply by arbitrarily moving the position of the antenna element on the spherical surface of the spherical lens.

  FIG. 8 shows an outline of a lens antenna device 100 using a general Luneberg hemispherical lens. This lens antenna device 100 transmits / receives radio waves to / from a hemispherical lens 101 that focuses a radio wave beam, and a radio wave reflector 102 that is attached to a half-section of the hemispherical lens 101 and reflects radio waves incident on the hemispherical lens 101. The antenna element 103 is provided.

  When receiving a radio wave by using such a lens antenna device 100, the incoming radio wave P is bent by the hemispherical lens 101 and reaches the radio wave reflector 102. The radio wave P is reflected by the radio wave reflector 102 and focused on the antenna element 103. Even when the direction of the radio wave P changes, it is possible to receive the radio wave P by adjusting the antenna element 103 to the focus position of the radio wave P.

  Therefore, the lens antenna device 100 has an advantage that the drive system can be reduced in size because it is not necessary to rotationally drive the entire antenna each time the direction of arrival of radio waves changes, unlike a parabolic antenna device or the like.

  As a conventional lens antenna device, for example, as shown in Patent Document 1, a guide rail is provided which is installed in parallel along the peripheral surface of a hemispherical lens, and the radiator is self-propelled at an arbitrary position on the guide rail. Thus, a technique for capturing the focusing position of the radio wave beam is disclosed.

  However, the technique disclosed in Patent Document 1 is based on the premise that a hemispherical lens in which dielectrics having different dielectric constants are laminated on concentric spherical surfaces is used. For this reason, there existed a problem that the manufacturing period of a hemispherical lens became long and the manufacturing cost rose. In addition, the disclosed technique disclosed in Patent Document 1 has a problem in that power consumption is excessive because it is necessary to dispose the guide rail and the self-propelled means as described above. In addition, the disclosed technique of Patent Document 1 has a problem that incident radio waves are greatly attenuated in the process of passing through a hemispherical lens composed of multiple layers. That is, with the disclosed technique of Patent Document 1, it is not possible to achieve higher-sensitivity reception until the radio wave incident on the hemispherical lens is reflected by the radio wave reflector and captured through the radiator. There was a problem.

  Incidentally, in order to capture the focusing position of the radio wave beam by an antenna element as a radiator, in addition to adjusting the position of the radiator, for example, as shown in Patent Documents 2 and 3, the orientation of the hemispherical lens antenna is mechanically adjusted. A control method has been proposed. However, the disclosed techniques shown in Patent Documents 2 and 3 are not techniques focused on sensitive reception, and the control of the direction of the hemispherical lens antenna must be performed in combination with the position adjustment of the radiator. After all, there was a problem that it was not possible to reduce power consumption.

  In Patent Document 4, in addition to the configuration of Patent Document 1 described above, a tilt antenna is further attached to the antenna unit, and when the antenna level is out of the specified range, all control can be stopped. Has been proposed. In this lens antenna device, when the antenna is tilted, it is possible to prevent the position of the radiator from temporarily deviating from the focal point of the radio wave and unstable reception. However, similarly to Patent Document 1, the disclosed technique of Patent Document 4 needs to be provided with guide rails and self-propelled means, which can solve the problem of excessive power consumption. There wasn't.

  The lens antenna device disclosed in Patent Document 5 is provided with a mechanism for mechanically adjusting the direction of the hemispherical lens placed on the radio wave reflector. In the disclosed technique of Patent Document 5, it is not necessary to provide the guide rail and the self-propelled means as described above, and the entire system can be configured at a low cost, thereby reducing the RF loss and extending the life of the system. It can be extended.

  However, the technique disclosed in Patent Document 5 has a problem that the manufacturing cost increases because it is necessary to use a Luneberg lens composed of multiple layers having different dielectric constants as the hemispherical lens. In the disclosed technique of Patent Document 5, from the viewpoint of reducing the manufacturing cost, if a single hemispherical lens is used, there is a problem that the gain becomes low and reception with higher sensitivity cannot be realized.

  In addition to this hemispherical lens, improvement of the antenna element itself is also progressing. For example, the antenna disclosed in Patent Document 6 includes at least one insert made of a dielectric that is suspended and attached inside the opening of the horn antenna. By providing such an insert, the radiation patterns of the E-plane and the H-plane can be configured uniformly.

  However, this insert is not rotationally symmetric with respect to the center of the opening. For this reason, there is a problem in that it is difficult to configure an antenna that can use polarized waves without causing a polarization loss with a high axial ratio.

  Further, in order to manufacture the antenna element shown in Patent Document 6, a special manufacturing technique is required, and there is a problem that the manufacturing cost becomes expensive.

JP 2006-005951 A US Pat. No. 7,212,169 JP-A-2005-167402 JP 2007-006266 A U.S. Pat. No. 3,848,255 JP 2005-137010 A

  Accordingly, the present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a lens antenna device that can realize low-cost and high-sensitivity reception. is there.

  In order to solve the above-described problems, the present invention places a hemispherical lens composed of a single layer on a radio wave reflector and mechanically controls the direction of the lens antenna to thereby reduce the reflection angle of the radio beam with respect to the radio wave reflector. The lens antenna device includes a horn antenna that is adjustable and further includes a dielectric insert that receives a radio wave beam focused by a hemispherical lens.

  In other words, the lens antenna device according to claim 1 of the present application includes a hemispherical lens antenna in which a hemispherical lens obtained by placing a single spherical lens for focusing a radio wave beam into two substantially equal parts is placed on a radio wave reflector, and the hemisphere. An angle adjusting means capable of adjusting the reflection angle of the radio wave beam with respect to the radio wave reflector by mechanically controlling the orientation of the mold lens antenna, and an antenna element for receiving the radio wave beam focused by the hemispherical lens, The antenna element includes a horn antenna into which a dielectric insert is inserted.

  The lens antenna device according to claim 2 of the present invention is characterized in that, in the invention according to claim 1, the radio wave reflector has a disk shape having a diameter larger than the cross section of the hemispherical lens.

  The lens antenna device according to claim 3 of the present invention is characterized in that, in the invention according to claim 1, a plate-like lens is interposed between a cross section of the hemispherical lens and the radio wave reflecting plate.

  The lens antenna device according to claim 4 of the present invention is characterized in that, in the invention according to claim 1, the hemispherical lens further has a protruding portion whose outer peripheral edge protrudes outward.

  In the present invention having the above-described configuration, a hemispherical lens is configured by dividing a single spherical lens into approximately two equal parts, as compared with a case where dielectrics having different dielectric constants are laminated in multiple layers. It becomes possible to reduce the attenuation of the radio wave, to realize higher sensitivity reception, and to further reduce the cost of manufacturing the lens. In addition, the cigar-shaped focus distribution formed by configuring this hemispherical lens in a single layer can be captured by the dielectric insert inserted into the horn antenna in the above-described form, and the reduction in gain is suppressed. It becomes possible.

  Further, in the lens antenna device to which the present invention is applied, it is not necessary to particularly provide a radiator position adjusting means, and power consumption can be reduced.

It is a figure which shows the example of the mobile communication system to which the lens antenna apparatus which concerns on this invention is applied. It is a figure which shows the structure of the lens antenna apparatus provided in the moving body. It is a figure for demonstrating the detailed structure of a lens antenna apparatus. It is a figure for demonstrating the structure of an antenna element. It is a figure which shows each structural example of the hemispherical lens antenna applied to a lens antenna apparatus. It is a figure which shows the result of having simulated the radiation directivity pattern with respect to each sample shown in FIG. It is a figure which shows the result of having simulated the radiation directivity pattern about this invention and the prior art. It is a schematic diagram of a lens antenna device using a general Luneberg hemispherical lens.

  Hereinafter, as a best mode for carrying out the present invention, a lens antenna device for mobile communication that receives radio waves from an artificial satellite or a ground station will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a mobile communication system 2 to which a lens antenna device 1 according to the present invention is applied. The mobile communication system 2 realizes mobile communication between a mobile 3 such as an airplane and a ground station 50 installed on the ground. As an example of the moving body 3, a ship, a vehicle, an artificial satellite, a helicopter, or the like may be applied in addition to an airplane. Further, the mobile body 3 is not limited to the case where communication is performed only with the ground station 50, and the mobile body 3 may perform communication between the mobile bodies 3. When the mobile body 3 communicates with the ground station 50 or another mobile body 3, the mobile body 3 transmits and receives radio waves via the lens antenna device 4 provided in a part of the mobile body 3.

  FIG. 2A shows the lens antenna device 4 provided in the moving body 3. The lens antenna device 4 includes a hemispherical lens antenna 5 attached to a moving body 3 via a holder 8, an antenna element 6 that receives a radio wave beam focused by the hemispherical lens antenna 5, and the antenna. And a communication unit 7 connected to the element 6. FIG. 2B shows the lens antenna device 4 provided outside the moving body 3 and protected from wind pressure by the radome 9.

  For example, as shown in FIG. 3, the hemispherical lens antenna 5 includes an arm 51 attached to a holder 8 whose longitudinal direction extends toward the y axis that coincides with the central axis of the antenna element 6, A radio wave reflection plate 54 rotatably attached to the distal end and a hemispherical lens 55 installed on the radio wave reflection plate 54 are provided.

  The arm 51 has an arch shape, and a central portion thereof is attached to the holder 8 via a rotation drive mechanism 52. The rotation drive mechanism 52 includes a motor, a gear, and the like (not shown), and can arbitrarily rotate about the arm 51 as the y-axis center. A radio wave reflection plate 54 is attached to the tip of the arm 51 via a rotation drive mechanism 53. The rotation drive mechanism 53 is also composed of a motor, gears, and the like (not shown), and can be rotated at an arbitrary angle about the x-axis center in the figure. Incidentally, by combining the rotation driving mechanisms 52 and 53, it is possible to mechanically adjust the direction of the radio wave reflecting plate 54 and, in turn, the hemispherical lens 55 placed thereon.

  The radio wave reflector 54 has a disk shape with a diameter larger than that of the cross section of the hemispherical lens 55. The reason is that radio waves to be received are reliably captured even when they are incident on the hemispherical lens 55 at any angle. Actually, the size of the radio wave reflector 54 is determined from the allowable range of required antenna characteristics including gain and side rope.

  The hemispherical lens 55 placed on the radio wave reflector 54 is obtained by dividing a single spherical lens that can focus a radio wave beam into approximately equal halves. In other words, the hemispherical lens 55 is not formed by laminating dielectric materials having different dielectric constants on concentric spherical surfaces, but is constructed by forming a single dielectric material over one layer. The radio wave incident on the hemispherical lens 55 composed of one layer as described above is focused not on the point focus but on the cigar shape as shown in the distribution 59 shown in FIG. The distribution 59 should match the dielectric insert 63 in the actual antenna and is here shown separately for clarity.

  As shown in FIG. 4, the antenna element 6 includes a horn antenna 61 and a dielectric insert 63 inserted into an opening 62 in the horn antenna 61. Incidentally, the dielectric insert 63 is fixed at a substantially central position in the opening 62 via a disk-shaped radome 64.

  The horn antenna 61 is made of a metal or a conductive material, and has an inner surface that has a conical shape with the axis y as the center. Further, the horn antenna 61 has a shape with the largest diameter at the opening 62, and the diameter is gradually reduced as the base end portion 66 is advanced. The horn antenna 61 has a base end portion 66 connected to a waveguide 67.

  The dielectric insert 63 is composed of an ellipsoidal shape, and is composed of a material having a dielectric constant of 1 or more and having a low dielectric loss. The shape of the dielectric insert 63 is not limited to an ellipsoid, and may be a rectangular parallelepiped shape or any shape that extends in the longitudinal direction. Good. However, the longitudinal direction of the dielectric insert 63 needs to be fixed so as to be oriented from the opening 62 of the horn antenna 61 to the base end portion 66.

  The radome 64 is joined so as to close the opening 62 of the horn antenna 61. The radome 64 is made of a material such as a resin that has radio wave transparency and low thermal conductivity.

  Note that the lens antenna device 4 may cover the holder 8, the hemispherical lens antenna 5, and the antenna element 6 with a radome 9 as shown in FIG. 2B, for example. The material constituting the radome 9 is the same as that of the radome 64.

  The communication unit 7 is supplied with an output signal from the antenna element 6 and amplifies the signal at a high frequency, and performs frequency conversion to a low-frequency signal.

  In the lens antenna device 4 having the above-described configuration, the radio wave transmitted from the ground station 50 or another moving body 3 is incident from the surface of the hemispherical lens 55. At this time, if the lens is a spherical lens, the radio wave is focused in the lens, but in this embodiment, a hemispherical lens 55 obtained by dividing the spherical lens into two equal parts is used, and this is placed on the radio wave reflector 54. ing. For this reason, the radio wave focused by the hemispherical lens 55 is reflected by the radio wave reflector 54 on the cross section of the hemispherical lens 55. For this reason, the incident radio wave to the hemispherical lens 55 takes a plane symmetric with respect to the spherical lens. By arranging the antenna element 6 on the cigar-shaped focus having the distribution 59 described above formed by the hemispherical lens 55, this radio wave can be received. In addition, by transmitting a radio wave from the antenna element 6 in this state, it is possible to transmit the radio wave to the ground station 50 and other mobile objects 3. When radio waves are transmitted from the antenna element 6, the radio waves are in the opposite direction to the above-described path in the hemispherical lens 55.

  In the lens antenna device 4 to which the present invention is applied, the arm 51 is arbitrarily rotated about the y-axis and the x-axis, so that the radio wave reflector 54 and the hemispherical lens 55 placed thereon can be arbitrarily oriented. It becomes possible to adjust. Therefore, by adjusting the direction of the hemispherical lens antenna 5, the cigar-shaped focus position can be controlled to an arbitrary position. In the present invention, this is utilized, and the orientation of the hemispherical lens antenna 5 is adjusted so that the focal point is located on the antenna element 6 regardless of the arrival direction of the radio wave. For example, as shown in FIG. 2, even when the direction of arrival of radio waves changes from the direction indicated by the solid line to the direction indicated by the dotted line, by mechanically controlling the direction of the hemispherical lens antenna 5, The focal position can be reliably guided to the antenna element 6 side. In the mobile communication system 2 in which the direction of the transmitted radio wave constantly changes, the present invention that can realize the above-described functions is particularly useful.

  The lens antenna device 4 to which the present invention is applied is not limited to the embodiment described above. FIGS. 5A to 5D show configuration examples of the hemispherical lens antenna 5 applied to the lens antenna device 4.

  FIG. 5A shows an example in which the hemispherical lens 55 is further provided with a protruding portion 71 whose outer peripheral edge protrudes outward. The projecting portion 71 is configured to have a triangular cross section, and is configured such that the height thereof decreases toward the outside. Incidentally, the protruding portion 71 may be integrated with the hemispherical lens 55, or may be separately manufactured from the hemispherical lens 55 and subsequently joined thereto. Further, the cross-sectional shape of the projecting portion 71 is not limited to a triangular cross-section, and may be any shape.

  The dotted line in FIG. 5A corresponds to a cross section of the hemispherical lens 55 that is obtained by dividing the spherical lens into approximately two equal parts. That is, the hemispherical lens 55 is increased in thickness according to the height of the protruding portion 71, but is not limited thereto, and may be configured in any thickness. Further, the hemispherical lens 55 may be a member that directly joins the radio wave reflecting plate 54 with a cross-section obtained by dividing the spherical lens into approximately two equal parts without increasing the thickness according to the height of the projecting portion 71. Good.

  FIG. 5B shows an example in which a plate lens 72 is interposed between the hemispherical lens 55 and the radio wave reflection plate 54. The plate lens 72 is bonded to the cross section of the hemispherical lens 55 obtained by dividing the spherical lens into approximately two equal parts. For this reason, it becomes an external shape in which the plate thickness from the hemispherical lens 55 to the radio wave reflecting plate 54 is increased. Incidentally, the diameter of the plate lens 72 is substantially the same as the cross section of the hemispherical lens 55. As an alternative to the plate lens 72, the thickness of the hemispherical lens may be increased.

  FIG. 5C shows a hemispherical lens 55 obtained by roughly dividing the spherical lens into two equal parts, and a radio wave reflecting plate having a disk shape larger in diameter than the cross section of the hemispherical lens 55, as described in FIG. The example comprised by 54 is shown.

  FIG. 5D shows an example constituted by a hemispherical lens 55 obtained by dividing a spherical lens into approximately two equal parts and a radio wave reflecting plate 54 having a disk shape having the same diameter as the cross section of the hemispherical lens 55.

  In FIGS. 5A to 5D described above, the case where the dielectric insert 63 is always inserted into the horn antenna 61 as the antenna element 6 constituting the lens antenna device 4 is taken as an example. On the other hand, in the comparative example shown in FIG. 5 (e), the antenna element 81 made of a horn antenna in which the configuration of the dielectric insert 63 is omitted is applied, and the hemispherical lens antenna is shown in FIG. Similarly to d), the spherical lens 55 is composed of a hemispherical lens 55 obtained by dividing the spherical lens into two equal parts, and a radio wave reflector 54 having a disk shape having the same diameter as the cross section of the hemispherical lens 55.

  Hereinafter, the results of simulating the radiation directivity pattern for each of the configurations shown in FIGS. 5A to 5E will be described. Hereinafter, the hemispherical lens antenna 5 having the configuration shown in FIG. 5A is referred to as sample A, the hemispherical lens antenna 5 having the configuration shown in FIG. 5B is referred to as sample B, and the configuration shown in FIG. The hemispherical lens antenna 5 is a sample C, the hemispherical lens antenna 5 having the configuration of FIG. 5D is a sample D, and the hemispherical lens antenna 5 having the configuration of FIG.

In each of the produced samples A to E, the diameter of the hemispherical lens 55 was 5 wavelengths. Further, the dielectric constant ε _r of the hemispherical lens 55 and the dielectric insert 63 was set to 1.7. Further, for sample A, the shape of the protrusion 71 is triangular in cross section, the protrusion amount and height are 0.35 wavelengths, and the thickness of the hemispherical lens 51 is increased according to the height of the protrusion 71. Yes. For sample B, the plate thickness of the plate lens 72 was 0.35 wavelength.

  FIG. 6 shows a result of simulating a radiation directivity pattern by making each of the samples A to E having such a shape enter a circularly polarized wave of 30 GHz. The angle 0 ° in FIG. 6 is a reflection point of radio waves at the horn antenna 6, and the angle 90 ° is a reflection point of radio waves at 90 ° with respect to the Y axis of the horn antenna 6. From the results of FIG. 6, the peak gain in the radiation pattern tended to be high particularly in the samples A and B, and then the samples C and D followed. Sample E had the lowest peak gain in the radiation pattern. Therefore, it can be seen that Samples A to D as examples of the present invention have better radiation characteristics than Sample E as a comparative example.

  The reason for this is that the hemispherical lens 55 formed of a single dielectric layer over one layer does not have a point focus, but a cigar-shaped focus. According to the samples A to D, since the dielectric insert 63 is inserted into the horn antenna 61, the cigar-shaped focus distribution can be effectively captured by the dielectric insert 63. Particularly, the longitudinal direction of the dielectric insert 63 is fixed so as to be oriented from the opening 62 of the horn antenna 61 to the base end portion 66. For this reason, it is suitable for capturing the cigar-shaped focus distribution to be formed.

  Incidentally, it can be seen that the radiation characteristics of sample A are excellent between samples A and B, particularly at an angle away from the vicinity of the center. In addition, it can be seen that the sample C has overall better radiation characteristics than the sample D. For this reason, the most desirable shape as a hemispherical lens antenna is the configuration of sample A, followed by sample B, sample C, and sample D in this order.

  Thus, in the lens antenna device 1 to which the present invention is applied, the hemispherical lens 55 is configured by dividing a single spherical lens into approximately two equal parts, and dielectrics having different dielectric constants are stacked in multiple layers. Compared with the case where it is used, it becomes possible to suppress the attenuation of the radio wave, to realize higher-sensitivity reception, and to further reduce the manufacturing cost of the lens. In addition, a cigar-shaped focus distribution formed by configuring the hemispherical lens 55 in a single layer can be captured by the dielectric insert 63 inserted into the horn antenna 61 in the above-described form, and the gain can be increased. It is possible to suppress the decrease.

  Further, in the lens antenna device 1 to which the present invention is applied, it is not necessary to particularly provide a radiator position adjusting means, and it is possible to reduce power consumption.

  In order to further discuss the effectiveness of the present invention, as a further form, there is a hemispherical lens 55 having a diameter of 8 wavelengths and a protrusion 71 having a height of 0.35 wavelengths. FIG. 7 shows the results of the invention and peak gain simulating a conventional radiation pattern. In the conventional specification, the dielectric constant of the lens is 2.5, and it is composed of a normal horn antenna.

  As shown in the results of FIG. 7, the present invention was 26.5 dBic at 90 °, and the conventional specification was 26.5 dBic at 75 °. The weight of the lens in the present invention is 25 grams. The weight of the conventional lens is 41 grams. The present invention can satisfy 26.5 dBic required in a wide angle range, and can realize a weight reduction of 40%.

DESCRIPTION OF SYMBOLS 1 Lens antenna apparatus 2 Mobile communication system 3 Mobile body 4 Lens antenna apparatus 5 Hemispherical lens antenna 6 Antenna element 7 Communication part 8 Holder 9, 64 Radome 50 Ground station 51 Arm 52 Rotation drive mechanism 53 Rotation drive mechanism 54 Radio wave reflection Plate 55 Hemispherical lens 61 Horn antenna 62 Aperture 63 Dielectric insert 66 Base end 67 Waveguide

Claims (4)

A hemispherical lens antenna in which a hemispherical lens obtained by dividing a single spherical lens for focusing a radio wave beam into two substantially equal parts is placed on a radio wave reflector;
Angle adjusting means capable of adjusting the reflection angle of the radio wave beam to the radio wave reflector by mechanically controlling the direction of the hemispherical lens antenna;
An antenna element for receiving the radio wave beam focused by the hemispherical lens,
The lens antenna device, wherein the antenna element is a horn antenna into which a dielectric insert is inserted. The lens antenna device according to claim 1, wherein the radio wave reflecting plate has a disk shape larger in diameter than a cross section of the hemispherical lens. The lens antenna device according to claim 1, wherein a plate-like lens is interposed between a cross section of the hemispherical lens and the radio wave reflecting plate. The lens antenna device according to claim 1, wherein the hemispherical lens further includes a protruding portion whose outer peripheral edge protrudes outward.

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