JP2005229284A - Substrate type antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate type antenna where scanning is performed by simple constitution. <P>SOLUTION: In the substrate type antenna, feeding lines 3 and 4 comprising micro-strip lines and an antenna element 5 comprising a micro-strip line are formed on a dielectric substrate 2, a reflector 6 is installed at a prescribed angle α of inclination with respect to the substrate 2, and the reflector 6 is movable relatively with respect to the substrate 2 keeping the angle α of inclination. Directivity can be scanned by moving the reflector 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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, a 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 rotated 360 ° while being kept constant. The parabolic reflector may be fixed and the beam may be scanned in a fan shape by feeding the displacement near the focal point of the opening of the primary radiator. However, a 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 substrate type antenna in which a feeding line made of a microstrip line and an antenna element made of a microstrip line are formed on a dielectric substrate, and the substrate has a predetermined inclination angle. A reflecting plate is installed, and the reflecting plate is movable relative to the substrate while maintaining the tilt angle.

  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 dimension elements of the feeder line and the antenna element may be dimension elements that can obtain elliptical directivity without the reflector.

  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 ½λ 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 The distance between the two feed lines 4 on the open end line 3 (the distance between the two antenna elements 5 adjacent to each other in the longitudinal direction of the substrate 2) and the like. These dimension elements are integral multiples of the operating frequency 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 deviates intentionally from the dimension element that can obtain the omnidirectionality, for example, a dimension element that can obtain the elliptical directivity on the horizontal plane by using a value that cannot be simply obtained from the use frequency λ. doing. 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 at 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 is 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. 11.

  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 drawing, the angle at which the maximum gain is about 30 ° is the same as in FIGS. 9 and 11, but in FIG. 13, the side lobe is further eliminated, and the angles at which −3 dB becomes 0 ° and + 60 °. 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 ° at both ends of a reflecting plate 6 having an inclination angle α with respect to the substrate 2, respectively. As described above, when a plurality of reflection plates 8 are provided, the sizes of the reflection 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 Feed line 4 Feed line 5 Antenna element 6 Reflector 7 Coaxial feed line 8 Reflector (2nd reflector)

Claims (3)

  In a substrate type antenna in which a feed line made of a microstrip line and an antenna element made of a microstrip line are formed on a dielectric substrate, a reflector is installed with a predetermined inclination angle with respect to the substrate, and the reflector is A board-type antenna characterized in that it can move relative to the board while maintaining the tilt angle.   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. 3. The substrate type antenna according to claim 1, wherein the dimension elements of the feeder line and the antenna element are dimension elements capable of obtaining elliptical directivity without the reflector.

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