JP4260038B2 - Aperture antenna - Google Patents

Description

The present invention relates to an opening surface antenna with a reflector and the primary radiator.

  Conventionally, aperture antennas equipped with reflectors and primary radiators have been used for wireless communication using microwaves and millimeter waves, but aperture antennas have sharp directivity characteristics, especially long distances. If the aperture area of the reflector is increased and the gain is increased for communication, the beam width (power half-value width) becomes extremely narrow, which makes it difficult to adjust the direction when installing the antenna.

  Therefore, as a conventional method for easily adjusting the antenna direction of the aperture antenna, the GPS receiver is used to measure the latitude, longitude, and altitude of the location where the aperture antenna is to be installed, and to communicate with the measurement results. A method has been proposed in which the orientation (azimuth / elevation angle, etc.) of the aperture antenna is calculated from the position of the target location, which is the installation location of the other party, and the orientation of the aperture antenna is adjusted based on the calculation result (for example, , See Patent Document 1).

In addition, in the proposed adjustment method, it is impossible to confirm whether the aperture antenna to be adjusted for direction adjustment faces the direction of the antenna to be communicated with. This antenna is provided with a light source that emits beam light (laser light) in the same direction as the central axis of the antenna, and the other antenna is provided with a light receiving plate that receives the beam light, and the beam emitted from the light source It has also been proposed to adjust the antenna direction so that light can be received at a predetermined position of the light receiving plate (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 7-131228 JP 2002-271124 A

  However, in the above-described conventional adjustment method, when performing the adjustment work, the GPS receiver that measures the installation position of the aperture antenna, and the direction of the aperture antenna (azimuth / elevation angle) from the measurement result and the target location by the GPS receiver. Etc.) or an expensive device for adjusting the antenna direction, such as a light emitting and receiving device (light source and light receiving plate) for projecting and receiving beam light (laser light), must be prepared. There was a problem that preparation was troublesome and costly to adjust the direction.

  In particular, when beam light (laser light) is used to adjust the antenna direction, it is necessary to operate the light beam projector (light source) and light receiver (light receiving plate) separately installed on the two antennas. For this reason, workers must be arranged at the installation points of the respective antennas, and there is a problem that the adjustment work becomes extremely troublesome.

The present invention has been made in view of such problems, and without using an antenna direction adjusting device such as a GPS receiver or a light projecting / receiving device, the antenna direction can be easily set only at the installation point of the antenna to be adjusted. and to provide an open surface antenna capable of adjusting.

The invention according to claim 1 which has been made in order to achieve the object,
In an aperture antenna including a reflecting mirror that reflects radio waves, and a primary radiator disposed at a focal position of the reflecting mirror,
A support member that rotatably supports the primary radiator around a central axis of the reflecting mirror;
The support member is provided with a bolt for fixing the primary radiator,
The side of the primary radiator is engaged with the tip of the bolt, and when the primary radiator is rotated around the central axis, the primary radiator can be displaced in the central axis direction of the reflecting mirror. A groove is provided to guide and position the primary radiator from the optimum communication position where the directivity is the sharpest to the optimum adjustment position where the directivity is suitable for adjustment of the antenna direction. It is characterized by that.

  Therefore, according to this aperture surface antenna, the primary radiator is displaced around the axis of the reflecting mirror by rotating the primary radiator around the axis in a state where the primary radiator is mounted on the support member, and the position of the aperture antenna is changed to the aperture. It is now possible to shift from the optimal communication position where the directional characteristics of the planar antenna are the sharpest to the optimal adjustment position where the directional characteristics of the aperture antenna are suitable for adjusting the antenna direction, or vice versa. As a result, the antenna direction can be adjusted very easily.

That is, in the aperture antenna, the half-power width representing the sharpness of the antenna directivity changes according to the antenna gain, and the half-power width becomes sharper as the antenna gain increases. Further, the gain of the aperture antenna increases as the effective aperture area of the reflector increases.
Therefore, as in the present invention, if the primary radiator is displaced in the direction of the central axis of the reflecting mirror and the relative position between the reflecting mirror and the primary radiator is changed, the effective aperture area of the reflecting mirror changes, As a result, the gain of the antenna, that is, the power half width changes.

And, according to the aperture antenna of the present invention, the primary radiator is displaced in the direction of the central axis of the reflector, the position of the primary radiator, the optimum adjustment position from the optimum communication position or displaced in the opposite direction because it can be, at the time of adjustment of the antenna direction, first, by setting the optimum adjustment position the position of the primary radiator, also spread temporarily from the optimum communication position of the antenna beamwidth (half-power beam width), By roughly adjusting the antenna direction by adjusting the antenna direction so that it can receive the transmission radio wave from the communication partner, and then setting the position of the primary radiator to the optimal communication position, it returns the width) to the original narrow beam width, to finely adjust the antenna direction may be like.
Therefore, according to the aperture antenna of the present invention , the direction can be adjusted very easily even if the aperture antenna has a sharp directivity .

  Further, for this direction adjustment, a level measuring device that measures the reception level of the signal by the aperture antenna may be used, and a conventional device for adjusting the direction such as a GPS receiver or a beam light projecting / receiving device is used. Since there is no need to separately prepare the direction adjustment, it is possible to easily and inexpensively adjust the direction.

By the way, as the aperture surface antenna, the one constituted by one reflecting mirror and a primary radiator disposed at the focal position of the reflecting mirror, and the reflecting mirror according to claim 2, wherein the reflecting mirror is a main reflecting mirror. And a sub-reflector, and the sub-reflector is arranged to relay radio waves between the main reflector and the primary radiator (specifically, a Cassegrain antenna, a Gregory antenna, etc.) ing.

The present invention can be applied to any type of aperture antenna provided with a reflecting mirror and a primary radiator .

Embodiments of the present invention will be described below with reference to the drawings.
1A and 1B are explanatory views showing the entire configuration of a Cassegrain antenna 1 of a reference example related to the present invention , in which FIG. 1A is a partially broken side view in which a main reflector portion of the Cassegrain antenna 1 is broken, and FIG. It is the front view seen from the reflective surface side of a reflective mirror.

As shown in FIG. 1, the Cassegrain antenna 1 of this reference example includes a main reflecting mirror 10 whose reflecting surface is a paraboloid, a sub-reflecting mirror 20 whose reflecting surface is a hyperboloid, and a conical horn. A primary radiator 30 comprising:

  A hole 12 for placing the primary radiator 30 is formed at the center position of the main reflector 10, and the primary radiator 30 is provided around the hole 12 behind the main reflector 10. The arm portion 14a of the support member 14 that supports the frame is fixed. That is, the support member 14 is fixed to the rear of the main reflecting mirror 10 via the arm portion 14a. The primary radiator 30 is positioned and fixed through the support member 14 so that the opening of the horn faces the focal point of the main reflecting mirror 10 from the hole 12 of the main reflecting mirror 10.

  A transmitter / receiver 40 for transmitting and receiving radio waves of several tens of GHz through the primary radiator 30 is provided on the rear end side of the primary radiator 30 fixed to the support member 14. The receiver 40 can receive a communication signal or supply power from the outside via the coaxial cable 42.

  In addition, at four positions on the outer periphery of the main reflecting mirror 10, the arm portion 16 a of the support member 16 that fixes the sub reflecting mirror 20 is fixed in the vicinity of the focal position of the main reflecting mirror 10. In other words, the support member 16 is fixed in the vicinity of the focal position of the main reflecting mirror 10 via the four arm portions 16 a whose one ends are fixed to the main reflecting mirror 10. The sub-reflecting mirror 20 is arranged with the reflecting surface facing the reflecting surface of the main reflecting mirror 10 via the support member 16.

  By the way, in the Cassegrain antenna 1, in order to relay the radio waves collected by the main reflecting mirror 10 to the primary radiator 30 through the sub reflecting mirror 20, the sub reflecting mirror 20 is usually Of the two focal points on both sides of the reflecting surface, one of the focal points coincides with the focal point of the main reflector 10 and the other coincides with the phase center of the primary radiator 30.

  However, the Cassegrain antenna 1 has a sharp directivity, and particularly when the diameter of the main reflector 10 is several tens of centimeters or more, the half-power width representing the sharpness of the directivity is several degrees (in some cases, less than 1 degree). Therefore, adjustment of the antenna direction becomes very troublesome.

  For example, FIG. 3 shows the measurement result of the directivity characteristics of the Cassegrain antenna arranged such that the diameter of the main reflecting mirror 10 is 90 cm and the focal point of the sub-reflecting mirror 20 coincides with the focal point of the main reflecting mirror 10. In this measurement result, although the gain of the antenna was able to secure a large value of about 47.0 dB, the half value width of the power was 1 degree or less (actually 0.475 degree), and the antenna was measured while measuring the reception level. It can be seen that it is difficult to adjust the direction by changing the direction of the vertical and horizontal directions.

  In FIG. 3, (a) and (b) show that the Cassegrain antenna is arranged toward the transmitting antenna that transmits the reference radio wave, and the direction and the elevation angle at which the reception level is maximum are centered (0 degrees). It shows the measurement results of measuring the relative level change with respect to the reference level by displacing the direction in the horizontal direction and the vertical direction, respectively.

Therefore, in this reference example , the sub-reflecting mirror 20 can be arbitrarily changed between the above-described optimum communication position and an adjustment position whose focus is deviated from the optimum communication position.
That is, as shown in FIG. 2, in this reference example , a male threaded portion 22 having a rod shape and a thread formed on the outer periphery is provided on the side opposite to the reflecting surface of the subreflecting mirror 20 as a supporting member of the subreflecting mirror 20. The supporting member 16 is formed with a female screw portion 18 into which the male screw portion 22 can be screwed, so that the sub-reflecting mirror 20 can be screwed into the central axis of the main reflecting mirror 10 by the screwing of these screw portions 22 and 16. The sub-reflecting mirror 20 can be positioned at any position while being moved along.

  Further, a screw hole is formed in the support member 16 from the outer periphery toward the female screw portion 18, and a bolt 19 as a fixing member is inserted into the screw hole and tightened, whereby the sub-reflecting mirror 20 is attached. The support member 16 can be fixed so as not to move.

  In addition, a mark 22a is formed on the male threaded portion 22 of the sub-reflecting mirror 20 so as to indicate the optimum position during communication of the sub-reflecting mirror 20 and the optimum position during adjustment of the antenna direction by cutting a part of the thread. .

  That is, as shown in FIG. 2, the mark 22 a has an optimal communication position optimal for communication with the focal point of the sub-reflecting mirror 20 coincident with the focal point of the main reflecting mirror 10, the directivity characteristics at that time, and the sub-reflecting mirror 20. The optimum adjustment position and the directivity characteristics at that time for the rough adjustment of the antenna direction with the focal point greatly deviated, and the fine adjustment that is optimal for the fine adjustment of the antenna direction with the sub-reflector 20 slightly defocused. It consists of three types of marks each representing the adjustment position and the directivity characteristics at that time, and by aligning the rear end surface of the support member 16 with each mark position, the position of the sub-reflecting mirror 20 (by extension, the Cassegrain antenna 1 (Directional characteristic) can be set to a position (characteristic) optimum for communication or direction adjustment.

Therefore, according to the Cassegrain antenna 1 of the present reference example , at the time of installation, first, the sub-reflecting mirror 20 is arranged at the approximate adjustment position so that the half-power width can be widened and the transmission radio wave from the communication partner can be received. When the antenna direction is roughly adjusted and the transmission radio wave from the communication partner can be received, the sub-reflector 20 is arranged at the fine adjustment position to narrow the half-power width and transmit the radio wave from the communication counterpart. The antenna direction is finely adjusted so that the reception level is maximized, and then the sub-reflecting mirror 20 is arranged at the optimum communication position to return the half-power width to the original narrow half-width and tighten the bolt 19. By adjusting the antenna direction and positioning and fixing the sub-reflecting mirror 20 in the above procedure, the Cassegrain antenna 1 can be installed very easily. .

  That is, for example, in the case of a Cassegrain antenna in which the diameter of the main reflecting mirror 10 is 90 cm, the directivity characteristics when the sub reflecting mirror 20 is displaced 21 mm from the optimum communication position toward the main reflecting mirror 10 are as shown in FIG. Thus, although the gain of the antenna decreased from about 47.0 dB to about 31.2 dB, the power half-width increased from less than 1 degree to around 3 degrees. Further, if the sub-reflecting mirror 20 is further displaced from the optimum communication position, the half-value width of power is further increased. Therefore, when adjusting the direction by changing the antenna direction to the vertical and horizontal directions while measuring the reception level, the directional characteristics of the Cassegrain antenna 1 are changed by changing the position of the sub-reflecting mirror 20 as described above. By deteriorating, the direction can be adjusted very easily.

  Further, when adjusting the antenna direction in this way, a level measuring device (so-called level checker) for the reception level may be simply used, and the direction of a GPS receiver, a beam light projector / receiver, etc., as in the past. Since there is no need to prepare a separate adjustment device, the antenna direction can be adjusted easily and inexpensively.

  2, (a) is a partially broken side view of the sub-reflecting mirror 20 and the support member 16 as viewed from the lateral direction, and (b) is a right side view of (a). 4, (a) and (b) represent measurement results obtained by measuring the reception level in the same procedure as in (a) and (b) of FIG.

In the above reference example, the Cassegrain antenna 1 configured so that the directivity can be adjusted by changing the position of the sub-reflector 20 with respect to the main reflector 10 and the primary radiator 30 has been described.

However, to adjust the directivity of Cassegrain antenna 1 as described above, necessary to change the position of the sub-reflecting mirror 20 is not, in the present invention, changing the position of the primary radiator.
Therefore, as an embodiment of the present invention, a case where the position of the primary radiator 30 in the Cassegrain antenna 1 of the above reference example is changed will be described.

As shown in FIG. 5, in the Cassegrain antenna of this embodiment , a bolt 34 is provided on the support member 14 that fixes the primary radiator 30 to the main reflecting mirror 10, and the bolt 34 is provided on the side surface of the primary radiator 30. It engages the distal end, the time of rotating the primary radiator 30 about the axis, Ru a groove 32 which displaceably guided along the primary radiator 30 to the central axis of the main reflecting mirror 10.

  That is, in this way, by rotating the primary radiator 30 around its axis in a state where the primary radiator 30 is mounted on the support member 14, the opening of the primary radiator 30 coincides with the reflecting surface of the main reflector 10 and directivity characteristics are obtained. From the optimal communication position where the sharpest point becomes the sharpest, the opening of the primary radiator 30 protrudes from the reflecting surface of the main reflector 10 and the directivity becomes a characteristic suitable for adjustment of the antenna direction, or in the opposite direction. As a result, it is possible to adjust the direction of the antenna very easily as in the above embodiment.

Incidentally, In Fig. 5, (a) shows the is a front view showing a state viewed primary radiator 30 mounted to the support member 14 from the rear of the main reflecting mirror 10, the (b) is (a) It is a right view, (c) is the top view which looked at the primary radiator 30 from upper direction in (b).

  As is apparent from this figure, a groove 32 is formed obliquely on the upper half of the side surface of the primary radiator 30, and when the primary radiator 30 is rotated around its axis, the primary radiator 30 It will be displaced along the groove while rotating along the groove.

  Next, in the above embodiment, a cassegrain antenna having two reflecting mirrors of the main reflecting mirror 10 and the sub-reflecting mirror 20 is described as an example of the aperture antenna to which the present invention is applied. Like the Cassegrain antenna, it is a Gregory antenna having two reflecting mirrors, a general parabolic antenna having only one reflecting mirror, or a sub-reflecting mirror or primary radiator is used as a main reflecting mirror ( Even an offset parabolic antenna deviating from the central axis of a single reflecting mirror can be applied in the same manner as in the above embodiment to obtain the same effect.

For example, the antenna shown in FIG. 6 represents a parabolic antenna having an offset type and a single reflecting mirror 60. If this type of offset type parabolic antenna is used, an arm portion having one end fixed to the reflecting mirror 60 is used. What is necessary is just to comprise the supporting member 80 for fixing the primary radiator 30 to 70 so that the primary radiator 30 can be supported so that the displacement to the axial direction is possible.

It is explanatory drawing showing the whole structure of the Cassegrain antenna 1 of a reference example . It is explanatory drawing showing the structure of the subreflecting mirror shown in FIG. 1, and its supporting member. It is explanatory drawing showing the measurement result of the directional characteristic of a Cassegrain antenna when the focus of a subreflecting mirror is made to correspond with a main reflecting mirror. It is explanatory drawing showing the measurement result of the directional characteristic of a Cassegrain antenna when the focus of a subreflector is shifted from the main reflector. It is explanatory drawing explaining the mechanism which displaces a primary radiator with respect to a main reflective mirror. It is explanatory drawing at the time of applying this invention to an offset type parabolic antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cassegrain antenna, 10 ... Main reflector, 12 ... Hole part, 14 ... Support member, 16 ... Support member, 18 ... Female thread part, 19 ... Bolt, 20 ... Subreflector, 22 ... Male thread part, 22a ... Mark, 30 ... primary radiator, 32 ... groove, 34 ... bolt, 36 ... mark, 38 ... scale, 40 ... transmitter and receiver, 42 ... coaxial cable, 60 ... reflector, 70 ... arm portion, 80 ... support member .

Claims (2)

In an aperture antenna having a reflecting mirror that reflects radio waves, and a primary radiator disposed at a focal position of the reflecting mirror,
A support member that rotatably supports the primary radiator around a central axis of the reflecting mirror;
The support member is provided with a bolt for fixing the primary radiator,
The side of the primary radiator is engaged with the tip of the bolt, and when the primary radiator is rotated around the central axis, the primary radiator can be displaced in the central axis direction of the reflecting mirror. A groove is provided to guide and position the primary radiator from the optimum communication position where the directivity is the sharpest to the optimum adjustment position where the directivity is suitable for adjustment of the antenna direction. An aperture antenna characterized by that . The reflector, aperture antenna as set forth in claim 1, wherein the main reflector, in that it consists of sub-reflecting mirror that relays radio waves with in between the main reflector the primary radiator.

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