JP4713838B2 - Substrate antenna - Google Patents

Description

  The present invention relates to a substrate type antenna used for a base station antenna for mobile communication, and more particularly to a substrate type antenna capable of scanning with a small and simple configuration.

  Nondirectionality over a relatively wide band (omnidirectionality in a horizontal plane) by a substrate-type antenna in which a feed line consisting of a microstrip line and an antenna element consisting of a microstrip line are formed on a substrate standing upright with respect to a horizontal plane There is known a technique for obtaining (see, for example, Patent Document 1).

  Also, a technique is known in which an antenna having directivity with a finite width is used, and the directionality (beam direction) of the directivity is changed (scanned) stepwise or continuously to a desired angle. For example, Patent Document 2 describes an apparatus that scans directivity by mechanically moving an antenna. Patent Document 3 describes an apparatus that electronically scans directivity by changing the electrical conditions of individual element antennas constituting an array antenna.

JP-A-11-31915 Japanese Unexamined Patent Publication No. 2-33322 JP-A-7-183717

  The electronic scanning antenna has the advantage that the directivity can be switched instantaneously, but it requires a plurality of element antennas and a plurality of variable phase shifters and element antenna arrays that change the phase amount of each element antenna array. Since a switch or the like for individually selecting a device is necessary, the device configuration and control become complicated.

  In general, the mechanical scanning antenna is used when the opening of the primary radiator is at the focal position of the parabolic reflector and the relative positional relationship between the primary radiator and the parabolic reflector is kept constant at 360 °. In some cases, the parabolic reflector is fixed and the beam is scanned in a fan shape by feeding the displacement near the focal point of the opening of the primary radiator. However, the primary radiator or parabolic reflector is required. Therefore, the apparatus configuration is complicated and large.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a substrate type antenna that can be scanned with a simple configuration.

In order to achieve the above object, the present invention provides a dielectric substrate having a longitudinal direction set perpendicular to a horizontal plane, an open-ended line composed of a microstrip line extending in the longitudinal direction of the substrate on one surface of the substrate, A plurality of antenna elements composed of microstrip lines formed on the substrate parallel to both sides of the open end line and spaced in the longitudinal direction of the substrate, and the plurality of antenna elements and the open end line are connected. In a substrate type antenna including a feed line made of a microstrip line, the substrate is provided with a predetermined inclination angle so as to obtain a desired directivity angle on the horizontal plane, and the longitudinal direction is set perpendicular to the horizontal plane. A reflection plate, wherein the substrate and the reflection plate are relatively movable in a width direction of the reflection plate with the inclination angle being constant, and the substrate is The antenna element has an electrical length of ½λ (λ: used wavelength), and the dimension element of the substrate type antenna is defined as (1) the length of the feeder line, (2 Non-directivity is obtained for at least one of the above-mentioned dimension elements as the distance between two feeding lines adjacent in the board longitudinal direction, and (3) the distance between two antenna elements adjacent in the board longitudinal direction. In order to deviate from the dimension elements to be obtained and to obtain elliptical directivity, the value is different from an integral multiple of the wavelength used or an integral multiple of an integral number, and in the width direction of the reflector by relative movement of the substrate and the reflector. The substrate-type antenna is characterized in that the direction of directivity on the horizontal plane from the antenna element is changed to a predetermined angle in accordance with a change in the distance between one end of the substrate and one end of the reflector.

  A second reflecting plate having an inclination angle different from the predetermined inclination angle with respect to the substrate may be provided integrally with the reflecting plate.

  The present invention exhibits the following excellent effects.

  (1) Since the directivity can be scanned only by changing the distance between the substrate and the reflecting plate, the configuration of the antenna can be simplified.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the antenna 1 according to the present invention has a feed line 3 (3 is also referred to as an open-end line) formed of a microstrip line extending in the longitudinal direction of the substrate 2 on one surface of the substrate 2. ), An antenna element 5 made of a microstrip line, and a feed line 4 made of a microstrip line connecting the feed line 3 and the antenna element 5, and a ground conductor 10 is formed on the other surface of the substrate 2. A substrate type antenna is used. The antenna element 5 has an electrical length of 1 / 2λ (λ: used wavelength) in the longitudinal direction. In addition, the ground conductor 10 is located on the back side of the feeder 3, and a coaxial cable 9 for feeding power from an external transceiver (not shown) to the substrate is provided along the ground conductor 10. In the substrate type antenna of the present embodiment, the parasitic element 9 is provided at a position corresponding to the antenna element 5 on the opposite surface of the surface on which the antenna element 5 is formed. It is also possible to arrange them so as to be parallel to the antenna element 5.

The direction indicated by the z axis in the figure is the direction perpendicular to the horizontal plane. That is, the substrate 2 is installed with the longitudinal direction of the substrate 2 perpendicular to the horizontal plane. The dimension elements of the feed line 4 and the antenna element 5 that determine the directivity of the substrate type antenna 1 are the length of the feed line 4 (the distance between the open end line 3 and the antenna element 5) and the longitudinal direction of the board 2 two there are, such as the distance on the open-end line 3 of the feed line 4 (antenna spacing element 5 two longitudinally adjacent the substrate 2) to an integer multiple of these dimensions elements used wavelength λ Alternatively, omnidirectionality (circular directivity) can be obtained on a horizontal plane by setting an integer multiple of a simple integer. Details are described in Patent Document 1. An example of this circular directivity is shown in FIG. The gain at ± 180 ° (in the direction opposite to the x-axis in FIG. 1) is slightly smaller than the gain at 0 ° (in the x-axis direction in FIG. 1), but this is an experimental error.

In the present embodiment, the dimension element that can obtain the omnidirectionality is intentionally deviated, for example, a value that cannot be simply obtained from the use wavelength λ (that is, an integer multiple of the use wavelength λ or an integer multiple of a simple integer) using different values), it employs a dimension elements oval directivity can be obtained in a horizontal plane. For example, the distance between the two antenna elements 5 and 5 adjacent to each other in the longitudinal direction of the substrate 2 is changed. An example of the elliptical directivity thus obtained is shown in FIG. As shown in the figure, the gain at ± 180 ° is about 1 dB smaller than the gain at 0 ° (in the x-axis direction in FIG. 1), and the gain at ± 90 ° (in the y-axis direction in FIG. 1) is about 4 dB.

  1 and 2, the antenna 1 according to the present invention has a reflecting plate 6 provided with a predetermined inclination angle on a horizontal plane with respect to the substrate 2, and the reflecting plate 6 is kept at the above-described inclination angle. In contrast, it is configured to be relatively movable. In this embodiment, the inclination angle α is 45 °, but may be set any number of times in order to obtain a desired directivity.

  Now, it is assumed that the reflector 6 is in the initial position.

  The reflection plate 6 is installed appropriately separated from the substrate 2. The distance in the x-axis direction from the antenna element 5 to the reflection plate 6 may be adjusted so that the directivity shown in FIG. The width of the reflecting plate 6 in the y-axis direction is preferably adjusted so that the directivity shown in FIG. The length of the reflecting plate 6 in the z-axis direction is substantially equal to the length of the substrate 2 in the z-axis direction. In FIG. 1, only four stages of the antenna elements 5 are shown in the z-axis direction, but actually, the antenna elements 5 may be provided in more or less stages than the four stages.

  FIG. 5 shows the directivity on the horizontal plane when the inclination angle α of the antenna of FIG. 1 is 90 °, that is, when the reflector 6 is perpendicular to the substrate 2. As shown in the figure, directivity that is largely biased toward the semicircle on the side including 0 ° is obtained. Looking at an angle of −3 dB with reference to a gain of about 0 ° at which the gain is maximum, it is about ± 80 °. That is, a directivity angle of 160 ° is obtained.

  FIG. 6 shows the directivity on the horizontal plane when the inclination angle α of the substrate type antenna of FIG. 1 is 0 °, that is, when the reflector 6 is parallel to the substrate 2. As shown in the figure, directivity that is largely biased toward the semicircle on the side including 0 ° is obtained. Looking at an angle of −3 dB with reference to a gain of about 0 ° at which the gain is maximum, it is ± 45 °. That is, a directivity angle of 90 ° is obtained.

  The antenna 1 shown in FIG. 1 and FIG. 2 has an inclination angle α formed by the substrate 2 and the reflection plate 6 set to 45 ° which is between 90 ° and 0 °. Thus, the inclination angle α of the reflecting plate 6 with respect to the substrate 2 can be set to an arbitrary value in 360 °, and the directivity obtained by this inclination angle α is different. FIG. 7 shows the directivity on the horizontal plane when the inclination angle α of the antenna of FIG. 1 is 45 °. As shown in the figure, the angle at which the gain is maximum is shifted to about 10 °, and the angle at which −3 dB is also −40 ° and + 70 °, and it can be seen that the directivity is closer to the + angle side as a whole. .

  Next, the distance in the y-axis direction between one end of the substrate 2 and the reflector 6 in the antenna 1 shown in FIGS. In the present invention, the offset S is changed by moving the reflecting plate 6. FIG. 8 shows a state where the reflector 6 of the antenna 1 shown in FIG. 2 is moved. In FIG. 2, the center in the width direction of the substrate 2 and the center in the width direction of the reflector 6 are in the same position on the y-axis. However, in FIG. 8, the substrate 2 moves relatively in the minus direction on the y-axis. It is getting smaller. The substrate 2 and the reflector 6 may be moved relatively, but the substrate 2 is wired with the coaxial feeder 7 and is difficult to move, and the directivity is compared with the substrate 2 as the origin. Therefore, the reflecting plate 6 is moved here.

  FIG. 9 shows the directivity on the horizontal plane corresponding to the state of FIG. As shown in the figure, the angle at which the gain is maximum is shifted to about 30 °, and it can be seen that the directivity is closer to the positive angle side as compared with FIG. In this way, the directivity can be scanned simply by changing the offset S as shown in FIGS.

  Next, the antenna 1a shown in FIG. 10 is obtained by adding another second reflecting plate 8 to the antenna 1 of FIG. The reflecting plate 8 has a tilt angle different from the tilt angle α of the reflecting plate 6 on the horizontal plane with respect to the substrate 2. Here, the angle of inclination of the reflecting plate 8 with respect to the substrate 2 is made different by providing the reflecting plate 6 with an angle β. The reflector 8 is provided integrally with the reflector 6 and is moved together with the reflector 6.

  FIG. 11 shows the directivity on the horizontal plane of the antenna 1a of FIG. As shown in the figure, the angle at which the gain becomes maximum is about 30 °, which is the same as in FIG. 9, but the side lobe seen at −60 ° in FIG. 9 is eliminated in FIG.

  An antenna 1b shown in FIG. 12 is obtained by adding another reflector 8 to the antenna 1 of FIG. Unlike FIG. 10, the angle (beta) of the reflecting plate 8 and the reflecting plate 6 differs, and is 90 degrees here.

  FIG. 13 shows the directivity on the horizontal plane of the antenna 1b of FIG. As shown in the figure, the angle at which the maximum gain is about 30 ° is the same as in FIGS. 9 and 11. However, in FIG. The ideal profile is obtained.

  As can be seen from the above description, in the present invention, the directivity can be scanned only by changing the offset S, which is the distance between the substrate 2 and the reflecting plate 6. The movement of the reflector 6 may be stepwise or continuous. If the reflecting plate 6 (or the reflecting plate 8 and the reflecting plate 6) is moved by an appropriate distance, the directivity in a desired direction, for example, the angle at which the gain becomes maximum as shown in FIG. Directivity can be realized. Unlike the conventional mechanical scanning antenna, the entire antenna including the radiator does not have to be moved, and unlike the electronic scanning antenna, it is not necessary to add complicated circuit elements. In addition, since the reflecting plate 6 only needs to be moved in one axial direction, the moving mechanism can also be configured simply. That is, according to the present invention, a substrate antenna capable of scanning can be manufactured at low cost with a small and simple configuration.

  The sizes of the reflecting plate 6 and the reflecting plate 8 may be appropriately adjusted in view of the directivity profile. For example, the antenna 1c shown in FIG. 15 has a narrower reflector 6 and a wider reflector 8 than the antenna 1b shown in FIG.

  Further, the reflecting plate 8 may be attached to both ends of the reflecting plate 6. The antenna 1d shown in FIG. 16 is provided with reflecting plates 8 and 8 ′ at an angle β = 90 ° on both ends of a reflecting plate 6 with an inclination angle α with respect to the substrate 2, respectively. As described above, when a plurality of reflecting plates 8 are provided, the sizes of the reflecting plates 8 and 8 'may be different.

  Next, an embodiment of a mechanism for moving the reflecting plate will be described.

  As shown in FIG. 17, the reflecting plate 6 is provided with a plurality of teeth 171 arranged in the moving direction of the reflecting plate 6. A gear 172 meshed with the teeth 171 is provided, and the gear 172 is rotated by a driving device such as a motor (not shown), whereby the reflector 6 can be moved and the offset S can be changed. Note that the teeth 171 may not be formed directly on the reflecting plate 6 but may be formed on a movable element integrated with the reflecting plate 6. The gear 172 may be a ball gear.

  Even if the configuration shown in FIG. 17 is not used, the present invention can be implemented as long as the mechanism allows the reflecting plate 6 to move relative to the substrate 2 with the inclination angle α.

It is a perspective view of a substrate type antenna showing one embodiment of the present invention. It is a top view of the board | substrate type antenna of FIG. It is a characteristic view which shows the circular directivity obtained from a board | substrate type antenna (state without the reflecting plate of this invention). It is a characteristic view which shows the elliptical directivity obtained from a board | substrate type antenna (state without the reflecting plate of this invention). It is a characteristic view which shows the directivity on a horizontal surface when the inclination | tilt angle (alpha) of the antenna of FIG. 1 is 90 degrees. It is a characteristic view which shows the directivity on a horizontal surface when the inclination | tilt angle (alpha) of the antenna of FIG. 1 is 0 degree. It is a characteristic view which shows the directivity on a horizontal surface when the inclination | tilt angle (alpha) of the antenna of FIG. 1 is 45 degrees. It is a top view which shows the state which moved the reflecting plate of the antenna of FIG. It is a characteristic view which shows the directivity on the horizontal surface of the antenna of FIG. It is a top view of the board | substrate type antenna which shows one Embodiment of this invention. It is a characteristic view which shows the directivity on the horizontal surface of the antenna of FIG. It is a top view of the board | substrate type antenna which shows one Embodiment of this invention. It is a characteristic view which shows the directivity on the horizontal surface of the antenna of FIG. It is a characteristic view showing directivity in a desired direction. It is a top view of the board | substrate type antenna which shows one Embodiment of this invention. It is a top view of the board | substrate type antenna which shows one Embodiment of this invention. It is a top view of the board | substrate type antenna which shows one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Board | substrate 3 Feeding line 4 Feeding line 5 Antenna element 6 Reflecting plate 7 Coaxial feeding line 8 Reflecting plate (2nd reflecting plate)

Claims (2)

A dielectric substrate installed with its longitudinal direction perpendicular to the horizontal plane;
One end surface of the substrate is formed of a microstrip line extending from the microstrip line extending in the longitudinal direction of the substrate, and a microstrip line formed on the substrate in parallel to both sides of the front end opening line and spaced in the longitudinal direction of the substrate. A plurality of antenna elements,
In the substrate-type antenna comprising the plurality of antenna elements and a feed line composed of a microstrip line connecting the open end wires ,
A reflector having a predetermined inclination angle so as to obtain a desired directivity angle on the horizontal plane with respect to the substrate, and having a longitudinal direction set perpendicular to the horizontal plane;
The substrate and the reflecting plate are relatively movable in the direction of the width direction of the reflecting plate while keeping the tilt angle constant,
The substrate is installed on the reflective surface side of the reflector,
The antenna element has an electrical length of ½λ (λ: wavelength used), and the dimensional elements of the substrate type antenna are (1) the length of the feeder line and (2) 2 adjacent to the longitudinal direction of the substrate. (3) As an interval between two antenna elements adjacent to each other in the longitudinal direction of the substrate, at least one of the above dimensional elements is deviated from the dimensional element capable of obtaining omnidirectionality and is elliptical. In order to obtain directivity, the value is different from an integer multiple of an operating wavelength or an integer multiple of an integer,
The direction of directivity on the horizontal plane from the antenna element is a predetermined angle according to a change in the distance between one end of the substrate and one end of the reflector in the width direction of the reflector due to relative movement of the substrate and the reflector. A substrate type antenna characterized by being changed to   2. The substrate type antenna according to claim 1, wherein a second reflecting plate having an inclination angle different from the predetermined inclination angle with respect to the substrate is provided integrally with the reflecting plate.

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