JP2014171115A - Thinning feed type array antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thinning feed type array antenna device with an improved radiation pattern and a higher degree of freedom in design.SOLUTION: A thinning feed type array antenna device comprises: a reflector plate 10; a feed element 20; a passive element 30; and a differential transmission path 40. The feed element 20 is a dipole type with length of approximately integer multiples of λ/2, and has a feeding point 21 to be offset from the center of the feed element 20 to one side. The passive element 30 is the dipole type with the length of approximately integer multiples of λ/2, has a junction 31 to be offset from the center of the passive element 30 to the other side, and is arranged approximately in parallel with the feed element 20. The differential transmission path 40 has length of approximately odd-number multiples of λ/2, and connects between the feeding point 21 and the junction 31.

Description

  The present invention relates to a thin-out feeding type array antenna apparatus, and more particularly to a thin-out feeding type array antenna apparatus in which a feeding element and a parasitic element are arranged on a reflector.

  2. Description of the Related Art Conventionally, a plurality of radiating elements are arranged, and some of them are parasitic elements, thereby simplifying a feeding portion without reducing antenna gain. For example, in Patent Document 1 and Patent Document 2, a plurality of feeding elements and parasitic elements are arranged, and side lobes radiated from the feeding elements are used to electromagnetically (spatically) feed elements and parasitic elements. ) An array antenna apparatus that is coupled to reduce the feeding portion is disclosed. In these elements, a feeding element and a parasitic element are arranged at a predetermined interval on a substantially parallel same plane that is separated from the reflecting surface of the reflecting plate by a predetermined distance.

  Since the array antenna device disclosed in Patent Literature 1 and Patent Literature 2 is electromagnetically (spatially) coupled to a parasitic element using a side lobe of the feeding element, the distance from the reflector and the feeding element The distance between the parasitic element and the parasitic element needs to be determined strictly. For this reason, the degree of freedom in design was poor. Furthermore, since each element is spatially coupled, the design is difficult and not practical for application to an antenna arranged on a curved surface such as a conformal array antenna device.

  Therefore, Patent Document 3 by the same applicant as the present application has been developed. That is, the thinned-feed array antenna apparatus of Patent Document 3 connects the center of the feed element and the parasitic element with a differential transmission path. As a result, an array antenna apparatus having a high degree of design freedom can be realized.

JP 2006-237781 A JP 2009-044610 A International Publication No. 2011/024990

  However, in the array antenna device of Patent Document 3, side lobes appear in the radiation pattern. In order to avoid this, it is disclosed that the interval between the feed element and the parasitic element is λ / 2 (where λ is the wavelength of the radiated wave). In the case of Patent Document 3, since the length of the differential transmission path needs to be λ, the differential transmission path having a length λ is arranged in a meander shape at a distance of λ / 2 between the elements. In addition, there is an apparatus that adjusts the impedance of the input impedance due to the influence of the reflector by offset power feeding. However, the meander-shaped differential transmission line may be affected by reflection and radiation, and it is difficult to design such as how to refract the meander shape.

  In view of such circumstances, the present invention intends to provide a thinned-feed array antenna apparatus with an improved radiation pattern and a higher degree of design freedom.

In order to achieve the above-described object of the present invention, a thinned-feed array antenna apparatus according to the present invention includes a reflector and a substantially λ / 2 (where λ is the wavelength of the radiated wave) disposed on the reflector. A dipole-type feed element having an integral multiple length, the feed element having a feed point offset to one side from the center thereof, and a length that is approximately an integral multiple of λ / 2 disposed on the reflector A dipole-type parasitic element having a connection point that is offset from the center to the other side, and a parasitic element that is arranged substantially parallel to the feeding element, and an odd multiple of approximately λ / 2 A differential transmission line having a length, which connects between a feeding point of the feeding element and a connection point of the parasitic element;
It comprises.

  Here, the feeding point of the feeding element and the connection point of the parasitic element may be offset to positions where the signals of the feeding element and the parasitic element are in phase.

  Further, the feeding element and the parasitic element may be arranged in a zigzag manner at positions substantially perpendicular to the differential transmission path.

  Further, the differential transmission path may be linear.

  In addition, the feeding element and the parasitic element may be arranged with an interval of approximately λ / 2.

  The differential transmission path may be meandered.

  Furthermore, a base material may be provided, the reflector is provided on the back surface of the base material, and the feeding element and the parasitic element are provided on the surface of the base material.

  Further, the differential transmission path may be provided on the surface of the base material or on the back surface of the base material through a via hole provided in the base material.

  Further, the substrate may have plasticity.

  Further, a plurality of feeding elements and parasitic elements may be continuously arranged.

  Further, a plurality of parasitic elements may be continuously arranged, and the differential transmission line may connect adjacent parasitic elements.

  Further, a shield member may be provided on the differential transmission path.

  The thinned-feed array antenna apparatus of the present invention has an advantage that the radiation pattern is improved and the degree of freedom in design is further increased.

FIG. 1 is a schematic plan view for explaining the basic configuration of the thinned-feed array antenna apparatus of the present invention. FIG. 2 is a schematic cross-sectional view through the feeding point for explaining the basic configuration of the thinned-feed array antenna apparatus of the present invention. FIG. 3 shows a phase distribution diagram of the surface current in the thinning-fed array antenna device of the present invention. FIG. 4 shows a radiation pattern of the thinned-feed array antenna apparatus of the present invention. FIG. 5 is a schematic plan view for explaining an example in which a plurality of feed elements and passive elements are alternately arranged continuously in the thinned-feed array antenna apparatus of the present invention. FIG. 6 is a schematic plan view for explaining an example in which a plurality of parasitic elements of the thinned-feed array antenna apparatus of the present invention are continuously arranged. FIG. 7 is a schematic plan view for explaining an example in which a plurality of elements of the thinning-feed type array antenna apparatus of the present invention are arranged linearly. FIG. 8 is a schematic cross-sectional view through a feeding point for explaining an example in which the base material of the thinning-feed type array antenna apparatus of the present invention has plasticity. FIG. 9 is a schematic perspective view for explaining an example in which a shield member is provided on the differential transmission path of the thinned-feed array antenna apparatus of the present invention. FIG. 10 is a schematic cross-sectional view passing through one of the differential transmission paths for explaining an example in which the differential transmission path of the thinned-feed array antenna apparatus of the present invention is provided on the back surface of the substrate.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described together with illustrated examples. FIG. 1 is a schematic plan view for explaining the basic configuration of the thinned-feed array antenna apparatus of the present invention. FIG. 2 is a schematic cross-sectional view passing through the feeding point for explaining the basic configuration of the thinned-feed array antenna apparatus of the present invention. As shown in the figure, the thinned-feed array antenna apparatus of the present invention is mainly composed of a reflecting plate 10, a feed element 20, a parasitic element 30, and a differential transmission path 40.

  The reflector 10 is made of, for example, a conductor, and is used to suppress the radiation in the back direction from the power feeding element and improve the gain in the front direction.

  The power feeding element 20 is disposed on the reflecting plate 10. The feed element 20 is of a dipole type having a length that is an integral multiple of approximately λ / 2 (where λ is the wavelength of the radiated wave). In addition, the feeding element 20 has a feeding point 21 that is offset from the center to one side (upper side in FIG. 1). The feeding element 20 is a radiating element in which radio wave energy is supplied to the feeding point 21 by the feeding unit 60. As shown in FIG. 2, when the thinned-feed array antenna device is formed using a base material 50 such as a printed circuit board, the feed point 21 is connected to the feed unit 60 via the via hole 51. The power supply unit 60 includes an electric signal source, an A / D converter, a balun, an amplifier, and the like for supplying radio wave energy to the power supply element 20.

  In the illustrated example, the array antenna device is configured using the base material 50. However, the present invention is not limited to this, and the base material may be used if the power feeding element can be fixed by a conductive wire or the like connected to the feeding point of the power feeding element. Of course, 50 may be omitted.

  A specific example of the dipole power feeding element 20 is a linear dipole antenna element as shown in the drawing. However, the feeding element used in the present invention is not limited to such a linear dipole antenna element, and may be any one such as a meandering dipole antenna element.

  The parasitic element 30 is disposed on the reflector 10. The parasitic element 30 is of a dipole type having a length that is approximately an integral multiple of λ / 2. The parasitic element 30 has a connection point 31 that is offset from the center to the other side (lower side in FIG. 1). The parasitic element 30 is disposed substantially parallel to the feeding element 20. The parasitic element 30 in the illustrated example has an element length substantially the same as that of the feeder element 20. However, the present invention is not limited to this, and the element lengths of the feed element and the parasitic element can be made different in order to increase the bandwidth of the array antenna device.

  The differential transmission path 40 connects between the feeding point 21 of the feeding element 20 and the connection point 31 of the parasitic element 30. The differential transmission path 40 has a length that is an odd multiple of approximately λ / 2. The differential transmission path 40 is, for example, a coplanar transmission path, and means two coplanar lines formed of a metal conductor on the substrate 50. The differential transmission path 40 is symmetrically connected with the feeding point 21 of the feeding element 20 and the connection point 31 of the parasitic element 30 in between so that the two lines are in opposite phases. That is, one of the upper and lower dipole elements is connected to each other. As a result, it is possible to suppress radio waves from being radiated from the differential transmission path 40.

  For example, in the example shown in FIG. 1, the feed element 20 and the parasitic element 30 are each arranged in a zigzag shape at a position substantially perpendicular to the differential transmission path 40. That is, in FIG. 1, the feeding element 20 is disposed on the lower side with respect to the differential transmission path 40, and the parasitic element 30 is disposed on the upper side. In addition, the differential transmission path 40 is a straight line in the illustrated example. That is, in this case, since the differential transmission path 40 has a length of λ / 2, the feeding element 20 and the parasitic element 30 are arranged with a gap of about λ / 2. It will be. Since the differential transmission line 40 only needs to have a length of λ / 2, it is not necessary to make a meander shape unlike the prior art. However, the thinning-fed array antenna device of the present invention does not necessarily have a linear shape. For example, when the interval between the feeding element 20 and the parasitic element 30 is narrower than λ / 2, the meander is necessary. It may be configured to have a length of λ / 2.

Here, the feeding point 21 of the feeding element 20 and the connection point 31 of the parasitic element 30 may be offset to positions where the signals of the feeding element 20 and the parasitic element 30 are in phase. FIG. 3 shows a phase distribution diagram of the surface current in the thinned-feed array antenna apparatus of the present invention. This figure shows the simulation results under the following conditions.
・ Center frequency is 2.45 GHz
The element length of the feed element 20 and the parasitic element 30 is λ / 2. The reflector is infinitely long and the distance from the element to the reflector is 5 mm.
The interval between the feeding element 20 and the parasitic element 30 is λ / 2 (that is, the length of the differential transmission path 40 is λ / 2).
-The offset position of the feeding point 21 of the feeding element 20 is 15 mm from the top.
-The offset position of the connection point 31 of the parasitic element 30 is 9.31 mm from the bottom.
・ Line width of differential transmission line 40 is 0.8mm
・ Distance between differential transmission lines 40 is 1mm.

  As shown in the drawing, it can be seen that the feeding element 20 and the parasitic element 30 are in phase under the above-described conditions. In this way, by performing offset power feeding at a position where they are in phase, a good radiation pattern can be obtained as shown in FIG. FIG. 4 shows a radiation pattern of the thinned-feed array antenna apparatus of the present invention. The radiation pattern of the figure is the yz plane (E plane: electric field amplitude plane of the antenna element) and zx plane (H plane: magnetic field amplitude plane of the antenna element) under the same conditions as the simulation conditions of FIG. This is a simulation result. Further, the angle is 0 ° on the z-axis, and since the reflector is infinitely long, there is no 90 ° or more. From the figure, it can be seen that the thinned-feed array antenna apparatus of the present invention has a good radiation pattern without the side lobe (quantization lobe) of the radiation pattern. Moreover, although the radiation pattern of the all-feed type array antenna apparatus is also shown as a comparative example, it can be seen that it matches well with these. Therefore, it can be seen that the same performance as that of the all-feed array antenna device can be obtained.

  As a specific structure for realizing the thinned-feed array antenna device of the present invention, for example, as shown in FIG. 2, the reflector 10 is provided on the back surface (surface opposite to the radiation direction) of the base material 50. The feeding element 20 and the parasitic element 30 are provided on the surface of the base material 50 (surface on the radial direction side). The differential transmission path 40 is provided on the surface of the base material 50. A via hole 51 is provided at the power feeding point 21 of the power feeding element 20 of the substrate 50, and the power feeding unit 60 is connected through the via hole 51. Thus, a thinned-feed array antenna device can be realized simply by forming a desired wiring pattern on a substrate by etching or the like. The substrate 50 may be a printed circuit board made of a dielectric, but may also be an insulating honeycomb plate having a honeycomb structure.

  In the thinned-feed array antenna apparatus of the present invention, the feed element 20 and the parasitic element 30 are physically coupled by such a differential transmission path 40. Therefore, unlike the prior art, it is not affected by the distance from the reflecting plate and the distance between elements, so that the degree of design freedom is improved. For example, the impedance adjustment can be greatly adjusted by the line width and line interval of the differential transmission path 40 and the offset position. Therefore, it is possible to adjust the impedance over a wide range with almost no influence on the distance to the reflecting plate 10.

  Moreover, a large-scale array antenna apparatus can be realized by arranging a plurality of elements having such a basic configuration. FIG. 5 is a schematic plan view for explaining an example in which a plurality of feed elements and passive elements are alternately arranged continuously in the thinned-feed array antenna apparatus of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. As shown in the figure, the feeding elements 20 and the parasitic elements 30 are alternately arranged, and the respective elements are connected by a differential transmission path 40. In the figure, one parasitic element 30 is sandwiched between the two feeding elements 20, 20, but in this case, a signal from a feeding unit that drives the two feeding elements 20, 20 is used. It is also possible to give a phase difference. Thereby, it is possible to scan the beam from the parasitic element.

  Furthermore, the thinned-feed array antenna apparatus of the present invention may be configured such that the feed elements and the passive elements are not alternated as shown in FIG. FIG. 6 is a schematic plan view for explaining an example in which a plurality of parasitic elements of the thinned-feed array antenna apparatus of the present invention are continuously arranged. In the figure, the parts denoted by the same reference numerals as those in FIG. As shown in the drawing, a plurality of parasitic elements 30 are continuously arranged with respect to the feeding element 20, and adjacent parasitic elements are also connected by a differential transmission path 40. Even in such a configuration, each parasitic element 30 behaves in the same manner as the feeding element 20 because the feeding element 20 and the parasitic element 30 are coupled by the differential transmission path 40. . Thus, since a plurality of parasitic elements can be radiating elements with one feeding element, it is possible to further reduce the number of feeding parts. In addition, the appearance pattern of a feeding element and a parasitic element is not limited to the above-mentioned illustration example, For example, you may arrange | position at random.

  In the illustrated example described above, the thinned-feed array antenna apparatus in which a plurality of elements are arranged in a zigzag shape is shown, but the present invention is not limited to this. For example, a plurality of elements may be arranged in parallel and linearly. FIG. 7 is a schematic plan view for explaining an example in which a plurality of elements of the thinning-feed type array antenna apparatus of the present invention are arranged linearly. In the figure, the parts denoted by the same reference numerals as those in FIG. As illustrated, in this example, the centers of the feeding element 20 and the parasitic element 30 are arranged in a straight line. In order to realize offset feeding, the differential transmission path 40 is obliquely connected to the feeding element 20 and the parasitic element 30. Even in this example, since the length of the differential transmission path is approximately λ / 2, the distance between the elements is narrower than λ / 2. Thus, the thinning-feed type array antenna apparatus of the present invention has a degree of freedom in element arrangement.

  Next, FIG. 8 shows a schematic cross-sectional view through a feeding point for explaining an example in which the base material of the thinning-feed type array antenna apparatus of the present invention has plasticity. In the figure, the parts denoted by the same reference numerals as those in FIG. As shown in the drawing, the thinned-feed array antenna apparatus of the present invention can use a base material 52 having plasticity, more specifically, a flexible print base material. Since the thinned-feed array antenna apparatus of the present invention physically couples each element using a differential transmission line, it functions as an array antenna without any problem even if the radiation direction of each element changes. is there. Therefore, the present invention can also be applied to an antenna arranged on a curved surface, such as a conformal array antenna device. That is, it is possible to realize a conformal array antenna device by simply forming the thinned-feed array antenna device of the present invention on a flexible printed substrate and pasting it on, for example, a curved surface of an aircraft body.

  In the thinned-feed array antenna apparatus of the present invention, the elements are connected by a differential transmission path. The differential transmission path is configured so that radio waves are not radiated from the differential transmission path because the two lines have opposite phases. However, there is a possibility of radiation from the differential transmission line for some reason. Therefore, in the example described below, a case where a shield member is provided on the differential transmission path will be described. FIG. 9 is a schematic perspective view for explaining an example in which a shield member is provided on the differential transmission path of the thinned-feed array antenna apparatus of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. In the illustrated example, the feed element 20 and the parasitic element 30, and the differential transmission path 40 that connects the feed element 20 and the parasitic element 30 are provided on the surface of the base member 50 on the radial direction side. The shield member 70 is disposed so as to cover the differential transmission path 40. The shield member 70 has conductivity, for example. If necessary, the shield member 70 may be electrically connected to the reflecting plate 10 provided on the surface opposite to the radial direction. By shielding the differential transmission path 40 with the shield member 70 in this way, it becomes possible to eliminate the influence of radiation from the differential transmission path 40.

  Furthermore, when a multilayer base material is used, a differential transmission path can be provided on the back side of the base material. FIG. 10 is a schematic cross-sectional view passing through one of the differential transmission paths for explaining an example in which the differential transmission path of the thinned-feed array antenna apparatus of the present invention is provided on the back surface of the substrate. In the figure, the parts denoted by the same reference numerals as those in FIG. As illustrated, for example, the base material is a three-layer base material 55, and the power feeding element 20 and the parasitic element 30 are provided on the surface of the base material. And the differential transmission path 40 is provided in the back surface of a base material via a via hole. Further, the reflecting plate 17 is disposed in the center layer of the three-layer base material 55. Thereby, since the radiation to the antenna radiation direction side from the differential transmission path 40 is blocked by the reflecting plate 17, the reflecting plate 17 also serves as the above-described shield member.

  In the case of a double-sided base material, a differential transmission path is disposed on the back surface of the base material, and a feed element and a parasitic element are provided on the surface of the base material, and a conductor is left as a shield member therebetween. May be.

  The thinned-feed array antenna apparatus of the present invention is not limited to the illustrated example described above, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Reflecting plate 17 Reflecting plate 20 Feeding element 21 Feeding point 30 Parasitic element 31 Connection point 40 Differential transmission path 50 Base material 51 Via hole 52 Base material 55 3 layer base material 60 Feeding part 70 Shield member

Claims (12)

A thinning-feed array antenna device that thins out feeding points, the thin-out feed array antenna device,
A reflector,
A dipole-type feed element having a length that is an integral multiple of approximately λ / 2 (where λ is the wavelength of the radiated wave) disposed on the reflector, and is offset from the center to one side. A feeding element having a point;
A dipole parasitic element having a length that is an integral multiple of approximately λ / 2 and disposed on the reflecting plate, and has a connection point that is offset from the center to the other side. Parasitic elements arranged in parallel;
A differential transmission path having an odd multiple of approximately λ / 2, the differential transmission path connecting between the feed point of the feed element and the connection point of the parasitic element;
A thinning-feed type array antenna apparatus comprising:   2. The thinned-out array antenna device according to claim 1, wherein the feeding point of the feeding element and the connection point of the parasitic element are offset to positions where signals of the feeding element and the parasitic element are in phase with each other. A thinning-feed array antenna device.   The thinned-out array antenna device according to claim 1 or 2, wherein the feeding element and the parasitic element are respectively arranged in a zigzag shape at a position substantially perpendicular to the differential transmission path. A thinning-feed array antenna device.   4. The thinned-out array antenna apparatus according to claim 1, wherein the differential transmission path is linear. 5.   5. The thinned-out array antenna apparatus according to claim 1, wherein the feeding element and the parasitic element are arranged with an interval of approximately [lambda] / 2. Antenna device.   4. The thinned-out array antenna apparatus according to claim 1, wherein the differential transmission path has a meander shape.   The thinned-out feeding type array antenna device according to any one of claims 1 to 6, further comprising a base material, wherein the reflector is provided on a back surface of the base material, and the feed element and the parasitic element are A thinned-feed array antenna apparatus, characterized in that the thinned-feed array antenna apparatus is provided on a surface of a substrate.   8. The thinning-feed array antenna apparatus according to claim 7, wherein the differential transmission path is provided on the surface of the base material or on the back surface of the base material through a via hole provided in the base material. Feed type array antenna device.   9. The thinning-feed type array antenna apparatus according to claim 7 or 8, wherein the base material has plasticity.   10. The thinned-feed array antenna apparatus according to claim 1, wherein a plurality of the feed elements and the passive elements are continuously arranged. 11.   The thinned-feed array antenna apparatus according to any one of claims 1 to 9, wherein a plurality of the parasitic elements are continuously arranged, and the differential transmission line connects adjacent parasitic elements. A thinning-feed array antenna device characterized by the above.   12. The thinned-feed array antenna apparatus according to claim 1, further comprising a shield member on the differential transmission path.