JPH11308019A - Array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an array antenna which is capable of connecting radiation elements at a strong electric field of a waveguide while using a waveguide having a little loss and adjusting the interval of the radiation elements, in accordance with antenna characteristic. SOLUTION: Plural radiation elements 1 are provided so as to connect to an electric field in the waveguide 2 along the tube axial direction of a ridge waveguide 2, whose both ends are short-circuited by short-circuit plates 2b and where ridges 2a are formed at a part of an inner wall. The elements 1 are respectively provided integrally with a probe 1a whose one end inserted into the waveguide 2 or are connected to the other end of the probe 1a. The waveguide 2 is provided with, e.g. a feeding part 3 into which a probe 3a for feeding is inserted from the bottom plane of which the ridge 2a is provided and can be connected to an external circuit through a connector 3b. And, by adjusting the height of the ridges, a waveguide which has a little loss can freely set an interval radiation elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna used as an aperture antenna such as a parabolic antenna, and more particularly to an array antenna in which radiating elements are arranged linearly or in a plane. More specifically, the present invention relates to an array antenna capable of extremely reducing signal radio wave attenuation and maintaining a high level of antenna characteristics such as directivity.

[0002]

2. Description of the Related Art As a conventional aperture antenna, a parabolic antenna whose surface is formed in a parabolic shape is used, as typified by a parabolic antenna. However, such a parabolic antenna has a three-dimensional structure and a large shape.
Since there is a problem that the aperture efficiency is poor, a linear or planar array antenna in which radiating elements are arranged in a linear or matrix form has recently been put to practical use as a method replacing this parabolic antenna.

Conventionally considered planar array antennas are, for example, strip line radiators as shown in FIGS. 8 (a) and 8 (b) and as shown in FIGS. 9 (a) and 9 (b). A slot type that radiates radio waves from a large number of slits 57 provided on a metal wall forming the cavity 58 has been considered. The strip line radiator is provided with patch antennas 51 arranged in a matrix on a dielectric substrate 52 having a ground plate 53 on the back surface. In order to supply power to each patch antenna 51, a dielectric 54 is further provided on the back of the ground plate 53. A strip line 55 is formed through the strip line 55, and power is supplied from the strip line 55 through a coupling pin 56. In the slot type, power is supplied to a radial waveguide 58 by a coupling pin 59 insulated, and an electromagnetic wave in the cavity is radiated through a slit 57. Note that, as shown in FIG. 9C, a structure in which a part of the radiating element 60 is inserted into the cavity 58 without direct radiation from the slit and coupled with an electric field in the cavity 58 to extract energy. There are also things. In this case, the radiated power is adjusted by changing the insertion depth of the radiating element 60 according to the strength of the electric field in the cavity 58.

[0004]

The conventional strip line type has a large transmission loss and deteriorates antenna characteristics, so that a high gain and high precision antenna cannot be obtained. In the case of the slot type, a slit is formed in the metal plate. However, the control range of the radiated power from the slit is narrow and there are many design restrictions. , Changes must be made to perform the trial production many times. Even if an optimal design value is obtained, it is difficult to obtain a sufficiently optimum antenna performance due to manufacturing variations.

Further, in the case of using a cavity, since the electric field distribution in the cavity varies depending on the radiating element, the radiated power from the radiating element cannot be easily set to a required value. Furthermore, these conventional array antennas cannot precisely adjust the magnitude and phase of the output of each radiating element, and there is a problem if a gain can be obtained like an antenna for satellite broadcast reception. Although it is good as an antenna for applications that do not become, for example, as an antenna for applications where a range to communicate in a narrow range and a range to not communicate are separated, such as an automatic toll collection system on a highway, Strict antenna characteristics such as a radiation pattern with a low side lobe level are required, and there is a problem that an antenna that satisfies the requirements cannot be obtained with the conventional array antenna.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and uses a waveguide having a small loss and adjusts the spacing between the radiating elements in accordance with the antenna characteristics to guide the radiating elements. An object of the present invention is to provide an array antenna that can be coupled at a place where the electric field of a wave tube is strong.

Another object of the present invention is to provide a planar antenna having a planar radiating element using the array antenna.

It is still another object of the present invention to transmit and receive orthogonally polarized signals such as right-handed and left-handed circularly polarized waves or horizontally and vertically polarized waves with one antenna. It is an object of the present invention to provide a planar array antenna which can be used.

[0009]

SUMMARY OF THE INVENTION An array antenna according to the present invention comprises a ridge waveguide having a ridge formed on one surface or two opposite surfaces of an inner wall; A coupling probe inserted perpendicular to the wide surface of the ridge waveguide; a radiating element provided integrally with the coupling probe or connected to the other end; And a power supply unit to be provided.

[0010] With this configuration, the guide wavelength can be changed by adjusting the height of the ridge of the ridge waveguide, and the distance between the radiating elements can be increased by using a waveguide thinner than a normal waveguide. Can be set freely. As a result, the spacing of the radiating elements can be adjusted while using a waveguide with low loss, depending on the desired characteristics, such as the spacing of the element antennas needed to lower the side lobe level of the radiation pattern. The distance between the radiating elements can be formed, and an antenna having desired characteristics can be obtained.

The ridge is formed so that the coupling probe is located at the abdomen of the electric field formed in the ridge waveguide, so that the coupling with the radiating element can be reliably obtained.

In order to form a planar antenna using this array antenna, a plurality of the ridge waveguides are arranged in parallel, and the ridge waveguides are arranged in parallel in order to supply power to respective feed portions of the plurality of ridge waveguides. A second ridge waveguide extending in a direction intersecting the plurality of waveguides, and a plurality of second coupling probes provided in the second ridge waveguide are directly connected to the plurality of ridge waveguides. The second ridge waveguide is provided with a second power supply unit which is used as a power supply unit of the waveguide or is connected to the power supply unit, and which can be connected to an external circuit.

A radiating element coupled to the plurality of ridge waveguides is formed for transmitting and receiving a signal of a first polarization, and a second element capable of transmitting and receiving a signal of a polarization orthogonal to the polarization. A plurality of third ridge waveguides to which the radiating elements are coupled, the first ridge waveguide and the third ridge waveguide are alternately arranged, and the third ridge waveguide is formed. A planar antenna capable of transmitting and receiving a plurality of polarized signals by providing a fourth ridge waveguide for feeding power to each of the tubes so as to extend in a direction intersecting the plurality of third ridge waveguides. Can be configured using a waveguide with low loss. The orthogonal polarization may be, for example, a combination of right-handed circular polarization and left-handed circular polarization in circular polarization, or a combination of horizontal polarization and vertical polarization in linear polarization.

The fact that a part of the tube wall of the ridge waveguide is formed by a single metal plate common to the plurality of ridge waveguides is required to form a planar array antenna.
This is preferable because ridge waveguides can be easily arranged at precise intervals.

[0015]

Next, an array antenna of the present invention will be described with reference to the drawings.

FIG. 1A is a perspective explanatory view of an example of a linear array antenna in which radiating elements 1 are arranged in a line, and FIGS. 1B to 1C show the BB line. , C
As shown in the sectional explanatory view of a part of the -C line,
Both ends are short-circuited by a short-circuiting plate 2b, and a longitudinal direction of the ridge waveguide 2 in which a ridge 2a of one side or two opposite sides (one side in FIG. 1) of the inner wall of the waveguide having a substantially rectangular cross section is formed. A plurality of radiating elements 1 are provided along. The radiating element 1 is integrated with a coupling probe 1 a having one end inserted into the ridge waveguide 2 at right angles to the tube axis direction and at right angles to the wide surface of the ridge waveguide 2, or for coupling. It is provided connected to the other end of the probe 1a. The coupling probe 1a is held at the tube wall portion of the ridge waveguide 2 via the dielectric 4 so that its position does not move and does not come into contact with the tube wall. Ridge waveguide 2
In the example shown in FIG. 1, the power supply probe 3a is inserted from the lower surface on which the ridge 2a is provided, and the connector 3b
And a power supply unit 3 that can be connected to an external circuit through the power supply unit.

The radiating element 1 is formed of a metal into an appropriate antenna shape, and as shown in FIGS. 4A to 4D, a curl element, a spiral element, a helical element, a zigzag element (plane (The antenna element folded back in). Various radiating elements for right-handed circularly polarized light, left-handed circularly polarized light, and linearly polarized light can be obtained depending on the shape. The radiating element 1 is integrated with the coupling probe 1a or connected to the coupling probe 1a, and is connected to the ridge waveguide 2 via a coupling probe 1a having one end inserted into the ridge waveguide 2. Combined with 2. The coupling probe 1a is made of, for example, phosphor bronze, and is provided at a place where the electric field E formed inside the ridge waveguide 2 is strong (antinode of the electric field), as shown in FIG. (Insertion length) changes the degree of binding, and the deeper the insertion, the stronger the binding. On the other hand, the interval between the coupling probes 1a is regulated by the interval between the radiating elements 1, and as described later, the interval between the radiating elements 1 is determined by antenna characteristics. The probe 1 for coupling is used while the interval between the radiation elements 1 according to the antenna characteristics is obtained.
The means for positioning the position a at a place where the electric field is strong will be described later.

As described above, the radiation power of the radiating element 1 is determined by the insertion depth, and one element of the antenna characteristic is determined. As another element that determines the antenna characteristic, the initial phase of each radiating element is set to a desired value. Adjustments must be made to obtain antenna characteristics. For example, a sharp beam can be obtained by matching all of the initial phases.
When a right-handed circularly polarized antenna is formed by using a curl element, as shown in a top view of FIG. 3, an initial angle is changed by changing an angle at which the adjacent radiating element 1 starts to rotate from the coupling probe 1a. The phase shift can be corrected. Even if it is not a curl element, the phase of the above-mentioned spiral element, helical element or the like can be similarly changed by changing the first folded portion.

As shown in the sectional view of FIG. 1B, the ridge waveguide 2 has a ridge (projection) made of metal on the bottom surface of a wide surface (H surface) of a rectangular waveguide of a signal to be used, for example. 2
a is continuously provided in the tube axis direction. The ridge 2a may be provided with a metal block on the bottom surface of the waveguide. However, the ridge 2a is not limited to the block, and at least the outer peripheral surface may be formed of a conductive material. Further, it may be provided not only on one wall surface but also on both opposing wall surfaces. By providing the ridge 2a, the interval S in the direction of the electric field of the waveguide is reduced, and the wavelength λ _c of the cut-off frequency of the ordinary waveguide is twice as large as the width A of the wide surface. As S becomes smaller, the wavelength λ _c of the cutoff frequency becomes larger than 2A. Therefore, the guide wavelength λ _g becomes shorter. That is, the guide wavelength λ _g
Is given by the following equation (1). Note that λ ₀ is a free space wavelength.

[0020]

(Equation 1)

As described above, the distance between the radiating elements 1 is set according to the antenna characteristics. That is, for example narrow when used to communicate with such a range, approximately 0.5～0.7Ramuda ₀ spacing of the radiating element 1 in order to reduce the side lobes of the radiation pattern of the antenna (lambda ₀ is the free space wavelength ). On the other hand, it is preferable that the coupling probe 1a connected to the radiating element 1 is inserted into a place where the electric field is strong in the waveguide. However, the electric field of the guide wavelength λ _g 1 /
It changes in two cycles, and the waveguide wavelength becomes larger than the free-space wavelength λ ₀ in the case of a normal waveguide, so that the interval between the radiation elements 1 cannot be narrowed, and desired characteristics cannot be obtained. However, by using the ridge waveguide of the present invention, as described above, it is possible to reduce the guide wavelength lambda _g, by selecting the height of the ridge 2a appropriately, the coupling probe 1a of the electric field The distance between the radiating elements 1 can be reduced while being inserted in a strong place.

In the example shown in FIG. 1, a through hole 2e is provided in the ridge 2a of the ridge waveguide 2, and the through hole 2e is provided.
The power supply probe 3a is inserted through the inside, and the other end of the power supply probe 3a is connected to the connector 3b, so that the power supply unit 3 is provided. Then, it is connected to an external circuit by a coaxial cable (not shown) or the like.
In order to match the impedance in the ridge waveguide 2 at the time of connection with the coaxial cable, a matching circuit (not shown) can be provided on the connector 3b side.

Next, an example in which a two-dimensional planar antenna is formed using the ridge waveguide array antenna will be described. FIG. 5A is a perspective view of one embodiment, and FIGS. 5B to 5C are cross-sectional views taken along the line BB and the line CC.

In this example, the linear array antennas using the ridge waveguide shown in FIG. 1 are arranged in parallel. Here, the metal part on the upper surface of the waveguide 2 is removed, and a plurality of waveguides are formed. So as to be closed by a single metal plate 2c common to the pipes,
A plurality of first ridge waveguides 2 whose upper surfaces are removed are arranged in parallel on the rear surface of the metal plate 2c. Also,
A through-hole is provided in a mounting portion of the radiating element 1 of the metal plate 2c,
One end of the coupling probe 1a is inserted into the ridge waveguide 2 via the dielectric 4, and the radiating element 1 is provided at the other end. Therefore, the structure of the portion of the array antenna in which the radiation element 1 is coupled to one first ridge waveguide 2 is as follows:
Similar to the example shown in FIG. 1 described above, in this example, a plurality of the array antennas are arranged in parallel to form a two-dimensional structure, and the plurality of first ridge waveguides 2 A second ridge waveguide 5 is further provided on the back side of the first ridge waveguide 2 so as to be able to supply power, for example, so as to cross (orthogonalize) the center of the ridge waveguide 2. I have. A connector 3b and a power supply probe 3a are provided on the bottom surface of the second ridge waveguide 5,
The power supply probe 3a is inserted into the cavity of the second ridge waveguide 5 through a through hole provided in the ridge 5a.
Then, a second coupling probe 1b is provided via a dielectric (not shown) so as to be connected to the cavities of the first and second ridge waveguides 2, 5, and the first ridge waveguide 2 is provided.
It is structured to be supplied with power.

That is, the power is supplied from an external circuit via the connector 3b and is coupled to the second ridge waveguide 5,
Of the ridge waveguide 5 and the plurality of first ridge waveguides 2 are coupled by the plurality of second coupling probes 1b, respectively, and supplied to the first ridge waveguide 2. I have.
The strength of this coupling can also be set freely by adjusting the insertion depth of the second coupling probe 1b. As a result, a signal can be radiated or received in a planar manner from the radiating element 1 provided in connection with each of the first ridge waveguides 2.

In the example shown in FIG. 5, the periphery of each radiating element 1 is covered with a conductor wall 6. That is, the metal plate 2 in which the conductor walls 6 form a lattice shape and constitute one wall surface of the ridge waveguide 2
Each radiating element 1 is provided in the cavity surrounded by the lattice-shaped conductor wall 6 and provided on the surface of C. Since the radiating elements 1 are surrounded one by one by the conductor wall 6 in this manner, the radiating elements 1 are placed in the rectangular cavity.
Is present and becomes a propagation mode in the waveguide,
The electromagnetic field distribution on the cavity opening surface becomes uniform. That is, in a radiating element that uses a phase change depending on the rotation direction such as a curl element, there is a problem that the characteristic in the θ direction varies from the direction of the coupling probe, but by providing the conductor wall 6, The individual characteristics of the radiating element 1 are constant, and the amplitude and phase of the individual radiating element are constant even at a wide angle of 60 ° or more from the normal direction.
Furthermore, there is no interaction between adjacent radiating elements,
The antenna characteristics are greatly improved. This conductor wall 6 is shown in FIG.
May be provided in a circle instead of a square as shown in FIG.

Although FIG. 5 shows an example in which four ridge waveguides are juxtaposed, the number is determined by juxtaposing n ridge waveguides so that required antenna characteristics can be obtained. Can be. Also, a matching circuit (not shown) is provided on the connector 3b side in the same manner as described above.

By using the ridge waveguide, the width of the ridge waveguide 2 can be reduced by adjusting the height of the ridge. As a result, the spacing between the radiating elements provided in the ridge waveguides to be arranged can be freely adjusted in accordance with desired antenna characteristics. As a result, the spacing between the radiating elements can be set according to the antenna characteristics, and the radiated power of each radiating element can be freely set by adjusting the insertion length of each coupling probe. The initial phase between the radiating elements can be adjusted by the mounting angle of the radiating elements. as a result,
A planar antenna having desired antenna characteristics can be obtained.

FIG. 6 is an explanatory view similar to FIG. 5A of still another embodiment of the planar antenna. In this example, an orthogonally polarized antenna is provided so that, for example, both right-handed and left-handed polarized waves can be transmitted or received. In this case, the right-handed circularly polarized wave is 12 GHz,
The left circularly polarized wave may be in a band different from 14 GHz. That is, for example, a right-handed array antenna in which the right-handed circularly polarized radiating element 1 is arranged in the first ridge waveguide 2, and a left-handed circularly polarized radiating element 9 are provided in the third ridge waveguide Waveguide 7
And left-handed array antennas arranged side by side and connected to each other. Then, the second ridge waveguide 5 for supplying power to the first ridge waveguide 2 and the fourth ridge waveguide 8 for supplying power to the third ridge waveguide 7 are provided.
They are provided so as to be orthogonal to the first and third ridge waveguides 2 and 7, respectively. Although not shown, the second and fourth ridge waveguides 5 and 8 are provided with a connector as described above so that power can be supplied to an external circuit.

In the present invention, since the ridge waveguide is used, the cutoff frequency of the ridge waveguide can be reduced by adjusting the height of the ridge, and the width of the ridge waveguide can be reduced. can do. As a result, even if, for example, the left-handed circularly polarized wave and the right-handed circularly polarized wave are alternately arranged in this manner, the left-handed circularly polarized wave and the right-handed circularly polarized light are each independently set to 0.5. it can be arranged at intervals of ~0.9λ _0.

In the example shown in FIG. 6, the radiating element 1 for clockwise rotation and the radiating element 9 for counterclockwise rotation are arranged so as to be shifted from each other. As shown in FIG. 6, it is preferable to dispose the right-handed circularly polarized wave and the left-handed circularly polarized light so that the distance between the radiating elements increases and the mutual influence can be reduced. Therefore, the second and fourth power supply
As shown in FIG. 6, the ridge waveguides 5 and 8 can supply power to the central portions of the first and third ridge waveguides 2 and 7 while being arranged side by side.

In the above-described example, the transmission and reception of orthogonal circular polarizations for right-handed circular polarization and left-handed circular polarization are performed. Antenna for orthogonal polarization. Further, in the example shown in FIG. 6, the radiating elements 1 and 9 are not surrounded by the conductor wall, but each radiating element is surrounded by the conductor wall as in the example shown in FIG. The influence can be eliminated, and the problem associated with the asymmetry of the radiation characteristic with respect to the inclination angle of the radiation element from the normal direction can be solved.

Further, in the above-described example, power is supplied to the first or third ridge waveguides 2 and 7 at the centers thereof, but power is supplied from another portion such as an end even if it is not the center. You can also.

In each of the above examples, the power supply probe is coupled via the through hole provided in the ridge, and the coupling probe is coupled by directly inserting the coupling probe into the cavity on the opposite surface.
Both can be bonded on the same surface, or the reverse bonding can be performed by bonding the bonding probe on the ridge side.

For example, as shown in FIG.
By providing the radiating element 1 on the side a, an impedance matching section 11 for matching the radiating element 1 and the characteristic measuring circuit can be formed inside the ridge 2a. The insertion length of the coupling probe 1a can be adjusted in a state where the impedance is matched by inserting the measured measuring jig (not shown). The impedance matching section 11 is formed in the metal of the ridge 2a by a hollow part concentric with the coupling probe 1a and having an inside diameter such that the impedance matches the impedance of the radiating element 1 with respect to the space. Is inserted. The dielectric portion 12 has a lid portion 12a integrated with the cylindrical portion 12b, and the center axis portion of the radiating element is fixed at the center thereof, and the dielectric portion 12 is inserted into the hollow portion of the ridge 2a. Radiating element 1
Are connected to and coupled to the coupling probe 1a. Reference numeral 13 denotes a position of the radiating element 1 when the dielectric portion 12
An alignment tab 14 for preventing vertical movement with respect to the first dielectric plate 14 is a second dielectric plate for ensuring the fixing of the coupling probe 1a, and 17 is a hole in a tube wall provided for adjusting the degree of coupling. A fixing pin made of a derivative screw or the like that closes and holds the coupling probe 1a, 4a is the coupling probe 1a
A dielectric ring interposed between the ridge 2a and the ridge 2a and holding the coupling probe 1 with a screw.

[0036]

According to the present invention, since the ridge waveguide is used, the guide wavelength can be shortened, and the distance between the radiating elements required by the antenna characteristics is set to a desired value while the dielectric material is used. As described above, it is possible to obtain a radiation characteristic with a small loss of the waveguide without a loss. As a result, for example, an antenna having a small side lobe, a high gain and a highly directional radiation pattern can be obtained, and the antenna can be reliably applied to transmission and reception in a narrow range such as an unmanned toll collection system of an automobile on a highway. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of an array antenna of the present invention.

FIG. 2 is an explanatory diagram of an insertion position of a coupling probe when coupling a waveguide and a radiating element.

FIG. 3 is an example of a shape when curl elements as an example of a radiation element are arranged.

FIG. 4 is a diagram illustrating an example of the shape of a radiating element.

FIG. 5 is an explanatory diagram of an example in which a planar antenna is configured using the array antenna of FIG. 1;

FIG. 6 is an explanatory diagram showing another example of the configuration of the planar antenna.

FIG. 7 is an explanatory sectional view of another embodiment of the array antenna of the present invention.

FIG. 8 is a diagram showing an example of a planar array antenna using a conventional patch element.

FIG. 9 is a diagram showing an example of a conventional planar array antenna using a cavity.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 radiating element 1 a coupling probe 2 ridge waveguide 2 a ridge 3 power supply section 3 a power supply probe 5 second ridge waveguide 7 third ridge waveguide 8 fourth ridge waveguide

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01Q 21/24 H01Q 21/24 (72) Inventor Hironori Okado 7-5-11 Takinogawa, Kita-ku, Tokyo Inside Yokohama Corporation

Claims (6)

[Claims] 1. A ridge waveguide having a ridge formed on one surface or two opposite surfaces of an inner wall, and a ridge waveguide perpendicular to the tube axis direction of the ridge waveguide and a wide surface of the ridge waveguide. A coupling probe inserted at a right angle, a radiating element provided integrally with the coupling probe or connected to the other end,
An array antenna comprising a feeder provided in the ridge waveguide. 2. The array antenna according to claim 1, wherein the ridge is formed such that the coupling probe is located at an abdomen of an electric field formed in the ridge waveguide. 3. The plurality of ridge waveguides are arranged in parallel, and intersect with the plurality of waveguides arranged in parallel in order to supply power to respective feed portions of the plurality of ridge waveguides. A second ridge waveguide extending in the direction is provided, and a plurality of second coupling probes provided in the second ridge waveguide are directly used as feed portions of the plurality of ridge waveguides, or 3. The array antenna according to claim 1, further comprising a second feeder connected to the feeder, and a second feeder provided in the second ridge waveguide and connectable to an external circuit, to form a planar antenna. 4. A radiating element coupled to the plurality of ridge waveguides is formed for transmitting and receiving a signal of a first polarization, and a second element capable of transmitting and receiving a signal of a polarization orthogonal to the polarization. A plurality of third ridge waveguides formed by coupling the radiating elements of
The first ridge waveguides and the third ridge waveguides are alternately arranged, and the plurality of fourth ridge waveguides for supplying power to the third ridge waveguides are provided. 3. The ridge waveguide of claim 3, wherein the ridge waveguide extends in a direction intersecting the ridge waveguide.
The array antenna described. 5. The array antenna according to claim 4, wherein the orthogonal polarization is vertical polarization and horizontal polarization in linear polarization, or right circular polarization and left circular polarization in circular polarization. 6. The array antenna according to claim 3, wherein a part of the tube wall of the ridge waveguide is formed of one metal plate common to the plurality of ridge waveguides. .