JPH01129511A - Microwave antenna - Google Patents

Abstract

PURPOSE:To realize a high gain, and also, to improve the degree of freedom of a design by providing a radiator for radiating an electromagnetic wave, and a sub-reflecting plate which is placed by leaving an electromagnetic wave radiating opening and reflects an electromagnetic wave, on the inside of a channel formed by a reflecting plate, and an opening of the channel, respectively. CONSTITUTION:A radiator 11 is placed in about the center in the longitudinal direction of a channel 10, and in about the center of a cross sectional space of the channel concerned 10. That is, the radiator 11 is placed in the center in the width direction of a vertical piece 12a of a reflecting plate 12 for constituting the channel 10 so that its dipole becomes parallel to the channel 10. A sub-reflecting plate 13 consists of a band-like metallic plate, and placed along the longitudinal direction of this channel 10 in a channel opening part 10a, and also, in about the center in the which direction of the channel opening part 10a. In this case, the sub-reflecting plate 13 is placed so as to cover the channel opening part 10a concerned by leaving an electromagnetic wave radiating opening 14a and 14b on both sides in the width direction of the channel opening part 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave antenna suitable for transmitting and receiving microwave relays, satellite broadcasts, radar, and the like.

[Prior Art] Conventionally, as this type of microwave antenna, for example,
There are some as shown in Figs. 4 to 6. The antennas shown in these figures are each composed of a dipole 1 and a reflector 2.

What is shown in FIG. 4 is a tie ball antenna with a reflector. In this antenna, microwaves radiated from the dipole antenna 1 are reflected by the reflector 2 due to the action of the reflector, and a beam is formed on the front surface and radiated.

The antenna shown in FIG. 5 is constructed by replacing the reflecting plate 2 with a corner reflector. This antenna is more efficient than the antenna shown in FIG. 4, and allows radiation from the tie ball antenna 1 to be radiated to the front with high efficiency.

Next, in the antenna shown in Fig. 6, the reflector 2 used in the antennas shown in Figs. This is an antenna constructed by providing the antenna. This antenna has further improved radiation efficiency than that shown in FIG. 4 or FIG. 5.

[Problems to be Solved by the Invention However, the above-mentioned conventional antenna has the following problems.

The problem is that the gain as a microwave antenna is low even if efficiency is improved. That is, the antenna shown in FIG. 4 has a power of about 6 dB, and the antenna shown in FIG.
The gain of the antenna shown in FIG. 6 is about 15 dB, and it was difficult to achieve a higher gain than this.

Further, in all of the above-mentioned conventional microwave antennas, once the structure type is set, the beam width and gain are uniquely determined, and there is a problem in that it is impossible to change these.

The present invention has been made to solve the above problems, and has achieved high gain.
The purpose of the present invention is to provide a microwave antenna that has a certain degree of freedom and can be designed arbitrarily without significantly changing its format.

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides a reflector plate that is arranged in a channel shape and reflects electromagnetic waves, and a reflector plate that emits electromagnetic waves into the channel formed by the reflector plate. and a sub-reflector that reflects electromagnetic waves and is disposed in the channel opening leaving an electromagnetic wave radiation opening.

The reflecting plate is arranged in a channel shape, and together with the sub-reflecting plate described later, constitutes a rectangular space in which electromagnetic waves emitted from the radiator described later resonate. In this case, in order to prevent electromagnetic waves from leaking behind the channel, it is preferable to form the channel integrally. However, it is only necessary that the channel can be constructed in a state where electromagnetic waves do not leak, and the channel may be formed by combining different members. In addition, this reflector is
Any member may be used as long as it has a surface that reflects electromagnetic waves; for example, a metal material, a synthetic resin material with a conductive layer formed on the surface, etc. can be used.

The radiator is preferably a 1/2 wavelength dipole or the like (
A dipole radiator is placed approximately in the center of the cross-sectional space of the channel. The radiator need only be able to radiate microwaves into the channel in a resonant manner, and is of course not limited to the above embodiment. For example, a structure in which the vibration is excited by a waveguide may be used. Moreover, the microwave antenna of the present invention is suitable for use as an antenna for electromagnetic waves having a wavelength of 15 GHz to 15 GHz. Of course, it is possible to apply to other wavelengths as well.

The sub-reflector plate may be any member having a surface that reflects electromagnetic waves, like the reflector plate, and may be made of, for example, a metal material, a synthetic resin material with a conductor layer formed on its surface, or the like. This sub-reflector is provided at the channel opening, preferably at the opening surface.
located along the channel. And preferably,
The channel opening is located approximately at the center in the width direction, and electromagnetic wave radiation openings are left on both sides of the opening to cover the channel opening.

The beam width and/or antenna gain of the sub-reflector is set by appropriately selecting its width, that is, the area of the sub-reflector relative to the area of the channel opening. For example, the opening width of the channel opening is 173~
The width is selected within the range of 1/2. In this case, the elongated direction is made to match the length of the channel.

Further, the sub-reflector may be formed to be expandable and contractible in its width direction. For example, by configuring two metal plates such that one side thereof is slidably stacked on top of the other, the overall width of the two stacked metal plates can be made variable. In this case, the width of the sub-reflector is determined by the desired beam width and/or
Or expand or contract it according to the gain you want to test.

The electromagnetic wave radiation apertures provided on both sides of the aperture in the width direction do not necessarily have to have the same aperture area (aperture width). Considering the symmetry of the formed beam and the sight loaf, they should have the same area (aperture width). It is preferable that the opening r7 width) be used.

Furthermore, in the present invention, a flexible plate that expands toward free space may be provided in the electromagnetic wave radiation opening provided in the channel opening.

Note that the microwave antenna of the present invention can be applied to any of horizontally polarized waves, vertically polarized waves, and circularly polarized waves.

[Function] In the antenna of the present invention configured as described above, when an electromagnetic wave is emitted from the radiator, this electromagnetic wave resonates within the rectangular space constituted by the channel made of the reflector and the sub-reflector, and some parts of the electromagnetic wave resonate. The electromagnetic waves are radiated to the outside from the radiation aperture.

At this time, if the electromagnetic wave radiation aperture is large, the electromagnetic field distribution on the channel aperture surface will be concentrated only in the vicinity of the radiator.

Therefore, the directivity in the antenna axis plane (in the polarization plane) becomes a float, and the gain does not become very large.

On the other hand, if the width of the sub-reflector is increased and its area is increased, the radiation aperture becomes narrower, making it easier for the electromagnetic field to be confined within the channel space, and this electromagnetic field is directed toward the antenna axis. Spread. That is, the electromagnetic field distribution spreads in the lateral direction of the aperture surface. This distribution has an almost exponential shape. Therefore, the directivity in the antenna axis plane is sharpened, and the gain is increased.

Here, in the case where the opening width of the channel opening is constant. According to experiments conducted by the present inventors, the relationship between the half-width of the beam and the directional gain with respect to the width of the sub-reflector is that for the electric plane (hereinafter referred to as E-plane), the width of the sub-reflector is increased. It was confirmed that the half-width of the beam decreases and the directional gain increases as the beam increases. On the other hand, regarding the magnetic interface perpendicular to the E plane (hereinafter referred to as the H plane), it was confirmed that the half width and directivity gain of the beam did not change much with respect to changes in the width of the sub-reflector.

Therefore, according to the present invention, the overall gain can be made larger than that obtained with conventional antennas of this type. For example, conventionally the maximum gain was about 15 dB, but the present invention allows a high gain of about 20 dB. Moreover, by changing the width of the sub-reflector, the gain can be set to a desired value within a certain range. For example, 12d
A desired value can be set within the range of B to 20 dB. That is, in the present invention, the beam width and gain can be designed arbitrarily to some extent without significantly changing the format.

This effect means that the gain of the antenna can be adjusted without using an expensive attenuator or the like.

Therefore, the present invention is also suitable for, for example, gain setting in relay antennas and the like.

In addition, in the present invention, by providing a flexible cable in the electromagnetic wave radiation aperture, the radiation impedance can be matched, and a higher gain can be achieved compared to an antenna with the same configuration without the flexible cable. It is said to reduce site loaf.

[Example] Embodiments of the present invention will be described with reference to the drawings.

<Configuration of First Embodiment> FIGS. 1A and 1B show the configuration of a first embodiment of the microwave antenna of the present invention.

The microwave antenna of the first embodiment shown in these figures is as follows:
A 172-wavelength Typole antenna is placed as a radiator 11 inside a reflecting plate 12 forming a channel 10 having a U-shaped cross section, and a sub-reflecting plate 13 is placed in the channel opening 10a. Ru.

The reflecting plate 12 is made of a metal material such as aluminum,
A vertical piece 12a and two parallel horizontal pieces 12b sandwiching it
It consists of. Vertical piece 12a and two parallel horizontal pieces 12b
are integrally connected and molded to form the channel 10.

The channel 10, together with the sub-reflector 13, constitutes a rectangular space that resonates the electromagnetic waves radiated from the radiator 11.

In this embodiment, the channel 10 is formed so that the length is 10, the width is 1.5, and the depth r is 0.5, taking into account the wavelength of the electromagnetic waves used. However, since it is sufficient as long as the interval is such that the electromagnetic waves resonate, the specific size is as follows.
Needless to say, this is not the only option. In addition, the length is normally only 4λ.

The radiator 11 is located approximately at the center of the channel 10 in the longitudinal direction, and is disposed approximately at the center of the cross-sectional space of the channel 10. That is, the radiator 11 is arranged with its tie ball parallel to the channel 10 at the center in the width direction of the vertical piece 12a of the reflecting plate 12 constituting the channel io. The radiator 11 may radiate microwaves into the channel 10 in a resonant manner, and is of course not limited to the above embodiment.

The sub-reflection plate 13 is made of a band-shaped metal plate, and is arranged in the channel opening 10a along the longitudinal direction of the channel IO and approximately at the center of the channel opening 10a in the width direction. At this time, the sub-reflector 13 is arranged to cover the channel opening 10a, leaving electromagnetic wave radiation openings 14a and 14b on both sides of the channel opening 10a in the width direction. In this embodiment, the electromagnetic wave radiation apertures 14a and 14b have the same area (aperture width).

This sub-reflector plate 13 is arranged parallel to the vertical piece 12a of the reflector plate 12, and the interval therebetween is set to be approximately equal to the depth of the channel 10. That is, it is set to about 1/2 of the wavelength of the electromagnetic wave used. However, as with the size of the channel 10, the size is not limited to this, as long as the distance is such that the electromagnetic waves resonate.

The width of the sub-reflector 13, that is, the area of the sub-reflector 13 relative to the area of the channel opening 10a, is appropriately selected in accordance with the intended beam width and/or antenna gain. For example, the width is selected within the range of 173 to 1/2 of the opening width of the channel opening 10a. In this case, the longitudinal direction is made to match the length of the channel 10. Specifically, a plurality of types of sub-reflection plates 13 having different widths in the range of 0.5 to 0.8 people may be prepared and selected as needed.

<Operation of the first embodiment> Next, the operation of the antenna of the present embodiment configured as described above will be explained.

First, when an electromagnetic wave is emitted from the radiator 11, this electromagnetic wave resonates within the rectangular space constituted by the channel 1O consisting of the reflector 12 and the sub-reflector 13, and a part of the electromagnetic wave is emitted to the outside from the electromagnetic wave radiation openings 14a and 14b. radiated. At this time, the central part of the opening surface 10a of the channel IO is located at the sub-reflector 13.
The radiation aperture for electromagnetic waves becomes narrower because it is covered with
The electromagnetic field is likely to be confined within the space of the channel 10, and this electromagnetic field is dispersed in the antenna axis direction, and the electromagnetic field distribution is expanded in the lateral direction of the aperture surface.

This distribution has an almost exponential shape. Therefore, the directivity in the antenna axis plane is sharpened, and the gain is increased.

The antenna of this embodiment has these electromagnetic wave radiation apertures 14a and 1.
A beam is formed by combining the electromagnetic waves radiated from 4b and 4b. As described above, this beam has different characteristics depending on the width of the sub-reflector 13.

Here, the relationship between the aperture area of the electromagnetic radiation apertures 14a, 14b and the characteristics of the electromagnetic beam formed will be explained with reference to FIGS. 2(A) to 2(C). In addition, in this embodiment, the opening area of the electromagnetic wave radiation openings 14a and 14b is as follows:
Since it is determined by the width of the sub-reflector 13, the width of the sub-reflector 13 is used here. In addition, Fig. 2 (A) and (
In B), the E plane is a plane that is orthogonal to the channel opening plane at its center and parallel to the channel depth direction, and the H plane is a plane that is perpendicular to the channel opening plane and the above E It is a plane perpendicular to the plane.

FIG. 2(A) shows the microwave antenna of this embodiment in which four types of widths of 0.5 mm, 0.6 mm, 0.7 mm, and 0.8 λ are selected and installed as the sub-reflector 13. The half-width characteristics at the electric surface are shown. In the figure, the horizontal axis shows the width d (in) of the selected sub-reflector 13, and the vertical axis shows the actual measured value (0) of the half-value width realized thereby. As is clear from this figure, the half-width at the E plane, indicated by point 0 in the figure, decreases as the width d (in) of the sub-reflector 13 increases.

For example, when the width d (in) of the sub-reflector 13 is 0.8, the angle is 19°. This is the width d(
In other words, the wider the width of the electromagnetic wave radiation aperture 14a
, 14b, the narrower the aperture width, the narrower the beam becomes.

On the other hand, regarding the H plane indicated by an x in the figure, the half-value width of the beam changes slightly as the width of the sub-reflector 13 changes.

That is, as the width d (in) of the sub-reflector 13 increases, the half-width of the beam decreases by several degrees.

In addition, in FIG. 2(B), as in FIG. 2(A) above, the width of the sub-reflector 13 is 0.5λ, 0.6 in, 0.7
4 shows the directional gain in the E plane and the H plane of the microwave antenna of this embodiment, in which four types of microwave antennas of 0.8λ and 0.8λ were selected and installed. In the figure, the horizontal axis shows the width d (in) of the selected sub-reflector 13, and the vertical axis shows the directivity gain (dB) realized thereby. As is clear from this figure,
The directional gain on the E plane, which is indicated by the zero point in the figure, increases as the width d (in) of the sub-reflector 13 increases. For example, when the width d(λ) of the sub-reflector 13 is 0.8λ, 1
It becomes 2dB. This indicates that the wider the width d (in) of the sub-reflector 13, that is, the narrower the aperture width of the electromagnetic wave radiation apertures 14a and 14b, the greater the directional gain.

On the other hand, regarding the H plane indicated by the X mark in the figure, the directivity gain of the beam decreases slightly as the width of the sub-reflector 13 changes. That is, as the width d (input) of the sub-reflector 13 increases, it decreases within a range of several dB.

It should be noted that the total gain can be determined from the directivity gains of the E plane and H plane shown in FIG. 2(B), and is about 20 dB for the antenna of this embodiment.

FIG. 2(C) shows the electromagnetic wave radiation pattern on the E side when the width d(λ) of the sub-reflector 13 is 0.8. As is clear from this figure, the antenna of this embodiment has a small sight roller and a radiation pattern that is preferable for an antenna.

In this way, in this embodiment, by only selecting the width of the sub-reflector 13 and without changing anything else, the half-width and the directivity gain can be set freely to a certain extent. Therefore, unlike conventional antennas of this type,
The beam width and gain can be designed arbitrarily to some extent without significantly changing the format.

<Configuration of Second Embodiment> FIGS. 3A and 3B show the configuration of a second embodiment of the microwave antenna of the present invention.

The microwave antenna of the second embodiment shown in these figures is as follows:
The electromagnetic wave radiation apertures 14a and 14b of the antenna configured in the same manner as in the first embodiment are provided with flares 15a and 16a and 16b and 15b. The configuration of this embodiment is the same as that of the first embodiment except for the fly section, so the explanation will focus on the differences here.

The flares 15a and 15b are provided at the tip of the parallel piece 12b of the reflecting plate 12, and are mounted with the tips expanding outward as flares for the entire channel IO. Further, the flares 16a and 16b are connected to the sub-reflector 13.
The structure is such that the cross section becomes triangular when both sides are connected. Of course, the arrangement of the flares 16a and 16b and the sub-reflector 13 does not necessarily have to be triangular in cross section.

Similarly to the antenna of the first embodiment, the antenna of this embodiment also has a channel 10 and a sub-reflection plate 13, so that the radiator 11
It constitutes a rectangular space that resonates electromagnetic waves radiated from. In this embodiment, this channel IO is formed so that the wavelength of the electromagnetic waves used is the input, the length is 10, the width is 1.5 people, and the depth r is 0.5 people. The width d of the sub-reflector 13 is 0.5λ, 0.6, 0.7λ, and 0.
, 8λ. Further, the distance S from the position of the sub-reflector 13 to the tips of the flares 16a, 16b is set to 1.0 people, and the distance F from the channel opening 10a to the tips of the flares 15a, 15b is: Set to 1.5 people. In this state, the opening end width W of the flares 15a and 15b
There will be three people. However, it goes without saying that the specific size is not limited to this, as long as it is an interval that allows electromagnetic waves to resonate.

<Operation of the second embodiment> The operation of the antenna of this embodiment is basically the same as that of the first embodiment, but due to the presence of the fray, side lobes can be reduced. That is, as mentioned above,
Regarding the H-plane, the beam directivity gain decreases within a range of several d13 as the width d (in) of the sub-reflector 13 increases with respect to a change in the width of the sub-reflector 13. This means an increase in sidelobes. In this embodiment, this side lobe is suppressed by fray, thereby suppressing an increase in the side lobe caused by increasing the beam directivity gain.

Furthermore, in this embodiment, the radiation impedances can be matched, and a higher gain can be achieved than in the first embodiment.

In this embodiment, only the width of the sub-reflector 13 is selected and the flare is added, and the side lobes are suppressed, and the half-width and directivity gain are adjusted to a certain degree without changing anything else. You can set it freely.

When the antenna of this example was actually measured, the overall gain was 23 dB, the H-plane beam width was 20a, and the E-plane beam width was 10°. Further, FIG. 3(C) shows the electromagnetic wave radiation pattern characteristics on the E side of the microwave antenna of this example.

<Other Embodiments> In each of the above embodiments, an example was shown in which a 172-wavelength tie ball was used as the radiator, but the present invention is not limited to this, and other radiators may be used. For example, a structure in which the vibration is excited by a waveguide may be used. Further, in each of the above embodiments, the example in which the tie poles are arranged horizontally is shown, but they may be arranged vertically.

Although each of the above-mentioned embodiments shows an example in which the reflective plate is formed of metal, the present invention is not limited to this, and the present invention is not limited to this. Any material that reflects electromagnetic waves such as objects may be used.

Furthermore, the sub-reflector 13 may have a structure that can be expanded and contracted in its width direction. For example, by configuring two metal plates such that one side thereof is slidably stacked on top of the other, the overall width of the two stacked metal plates can be made variable. By having such an expandable and contractible structure, it becomes possible to easily adjust the beam half width, gain, etc. at the antenna installation site. Therefore, since the gain can be adjusted without using an expensive attenuator, it is suitable for setting the optimum gain in, for example, a relay antenna.

Furthermore, in the above embodiment, the sub-reflector 13 is provided at the center in the width direction of the channel opening, and the electromagnetic wave radiation openings 14a, 14
Depending on whether the aperture width b is the same or the direction of the beam to be formed, it is not necessarily necessary to make them the same, and both may be made different depending on the intended beam.

[Effects of the Invention] As explained above, the present invention improves the gain, and also
It is possible to realize a microwave antenna that has a certain degree of freedom in designing the beam width and gain within the electric surface without significantly changing the format.

[Brief explanation of the drawing]

FIG. 1(A) is a perspective view showing the configuration of the first embodiment of the microwave antenna of the present invention, FIG. 1(B) is a side view thereof, and FIG.
Figure (A) is a graph showing the half-width characteristics of the microwave antenna of this example in the E plane and H plane, and Figure 2 (B) is a graph showing the directivity of the microwave antenna of this example in the E plane and H plane. FIG. 2(C) is a graph showing the electromagnetic wave radiation pattern characteristics on the E plane of the microwave antenna of this embodiment. FIG. 3(A) is a graph showing the second embodiment of the microwave antenna of the present invention. FIG. 3(B) is a perspective view showing the configuration of the example; FIG. 3(B) is a side view thereof; FIG. Figure 6 shows a conventional microwave antenna, and Figure 4 (
A), FIG. 5(A) and FIG. 6(A) are their front views, and FIG. 4(B), FIG. 5(B) and FIG. 6(B) are their sectional views. 10...Channel 10a...Channel opening 11...Radiator 12...Reflector 13...Sub-reflector 14a, 14b...Electromagnetic wave radiation opening 15a, 15b, 16a, l6b- ...Freya applicant Mogai Hasebe (1 person)

Claims (4)

[Claims] (1) a reflector arranged in a channel shape to reflect electromagnetic waves; a radiator that radiates electromagnetic waves into the channel formed by the reflector; arranged with an electromagnetic wave radiation opening left in the channel opening; A microwave antenna comprising a sub-reflector that reflects electromagnetic waves. (2) The microwave antenna according to claim 1, wherein the beam width and/or gain is set by selecting the area of the sub-reflector relative to the area of the channel opening. (3) The microwave antenna according to claim 2, wherein the sub-reflector is formed to be expandable and retractable in its width direction to set the beam width and/or gain. (4) The microwave antenna according to claim 1, 2, or 3, wherein the electromagnetic wave radiation aperture is provided with a flare that expands toward free space.