JPH05129831A - Surface wave line array antenna - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding a surface wave line array antenna, in particular, dipole arrays excited by surface waves are arranged substantially parallel to a metal surface constituting the array antenna, and circles are formed in a direction substantially orthogonal to the dipole arrays. The present invention relates to a surface wave line array antenna having a function of radiating or receiving polarized waves or linearly polarized waves. [Structure] A slow wave circuit composed of a dielectric 2 is installed on a single metal plate 1, and a mode in which a radial current flows almost radially on the metal plate 1 is used, and the plane is perpendicular to and parallel to this plane. A surface wave propagating in the radial direction is excited by an electric field excited in any direction, and the dipole arrays 3 and 3 excited by the surface waves are arranged substantially parallel to the metal plate 1 so that they are substantially orthogonal to the dipole array. It is characterized in that it radiates or receives a circularly polarized wave or a linearly polarized wave in the direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna, and more particularly to a surface wave line array antenna.

2. Description of the Related Art Conventionally, it has been known that electromagnetic waves (surface waves) propagate along a surface of a dielectric around the conductor when the conductor is arranged along with the dielectric. The transmission means is called a surface waveguide.

FIG. 19 shows, as an example thereof, a dielectric ε ₁ coaxially mounted along the outer circumference of a conductor C _{1 having} a circular cross section.
A surface wave line generally called a G-line is shown, and in this case as well, a surface wave propagates along the surface of the dielectric. The symbol E in the figure indicates the electric field and its distribution, and the broken line H indicates the magnetic field. A surface wave antenna that excites this surface wave and radiates it in the traveling direction of the wave has also been put into practical use, but it is not possible to obtain a large gain.

In the surface wave line described with reference to FIG. 19, it can be easily inferred that substantially the same action and effect can be obtained even when the conductor is a metal disk to form a disk type surface wave line. On the other hand, there have been proposed many array antennas in which two conductors are arranged with a space therebetween to transmit a radio wave in this space, and a slot is provided in the conductor so that the radio wave is radiated from this slot.

[0004]

By the way, there is a problem that a large gain cannot be obtained with the above-mentioned disc type surface wave line, and the above-mentioned array antenna has a little transmission loss and is expensive.

The present invention is intended to solve such a problem, and as shown in FIG. 20, a circle formed by closely contacting a dielectric ε ₂ on one surface of a metal disk C _2. In the plate-shaped surface wave line, when the surface wave line is excited by the monopole antenna by the center conductor D of the coaxial line attached to the center part of the metal disk C ₂ , the electric field E is directed toward the radial direction. By combining the principle known by the present inventor that it is uniformly generated in the direction and transmitted in the surface wave mode and the principle of the array antenna, a surface with a single metal plate and less transmission loss is formed. It is an object of the present invention to provide a circularly polarized wave antenna having a high gain by using a wave transmission system and by radiating radiation by a dipole array excited by an electric field excited in a direction orthogonal to and parallel to the transmission line.

In FIG. 20, the magnetic field H is formed in a circular shape in the circumferential direction as shown by the dotted line. The symbol i in the figure indicates a current flowing radially in the radial direction of the metal circular plate C ₂ .

When the surface wave line is excited from the coaxial line, as shown in FIG. 21, a circular metal plate M is placed at a position facing the mounting portion of the coaxial line Ex on the dielectric ε _2. By doing so, matching and excitation can be facilitated and unnecessary radiation can be suppressed. The shape of the disc may be concave or convex.

[0008]

In order to achieve the above-mentioned object, the surface wave line array antenna of the present invention has a slow wave circuit made of a dielectric material or a pseudo dielectric material on one metal plate, A mode in which a radial current flows almost radially on this metal plate is used, and a surface wave propagating in the radial direction is excited by an electric field excited in the direction perpendicular to and parallel to this plane, and is excited by this surface wave. The dipole array is arranged in parallel with the metal surface in a circular or spiral pattern, and has the function of radiating or receiving circularly polarized or linearly polarized light in a direction substantially orthogonal to this dipole array. I am trying.

[0009]

In the above-mentioned surface acoustic wave line array antenna of the present invention, the current flowing in the radial direction of the surface acoustic wave line formed by one metal plate and the dielectric or pseudo-dielectric is in the direction perpendicular to this plane. A surface wave propagating in the radial direction is excited by the excited electric field, and the dipole array excited by this surface wave acts to radiate or receive a circularly polarized wave or a linearly polarized wave in a direction substantially perpendicular to the metal surface. ..

[0010]

1 to 8 show a surface wave line array antenna as a first embodiment, FIG. 1 is a plan view thereof, and FIG. 3 is a sectional view taken along the line AA of FIG.
7 is a plan view showing an example of the arrangement of the dipoles, and FIG. 8 is an enlarged plan view showing another example of the arrangement of the dipoles. 9 to 14 show a surface acoustic wave line array antenna as a second embodiment of the present invention. FIG. 9 is a lateral cross-sectional view of a main part thereof, FIG. 10 is a schematic perspective view of the main part, and FIG.
Is a plan view, FIG. 12 is a schematic plan view for explaining the operation, FIGS. 13 and 14 are schematic side sectional views for explaining directivity, FIG. 15 is a plan view of a linear polarization array antenna, and FIG. 16 (a). FIG. 16 is a frequency characteristic diagram of the slow wave rate of the dipole array antenna, and FIG. 16 (b) is a frequency characteristic diagram of the slow wave rate of the conventional slot array antenna.

The surface acoustic wave line array antennas shown in FIGS. 1 and 2 also use the principle of the above-mentioned disk type surface acoustic wave line (see FIG. 20), and are C-shaped or T-shaped excited by the surface wave.
It is an array antenna that can generate circularly polarized waves from a letter dipole.

That is, the metal disc 1 is placed on the upper surface of the metal disc 1.
A dielectric 2 having the same shape as that of is closely attached, and further, on the upper surface of the dielectric 2, about 1/4 λg (λg = a slow wave of the dielectric 2 and a slow wave due to a dipole array, which results in the entire transmission line A large number of 3 and 3 are arranged along the helix R ₁ so as to form a pair of C-shaped dipoles which are arranged substantially orthogonal to each other in the radial direction by (wavelength). As a concrete example of the dielectric 2, when polyethylene or polystyrene having a dielectric constant ε = 2.3 is used, a suitable thickness is 3 to 5 mm, especially a thickness of 4 mm.
And good results were obtained. This is because the electrical distance between the dipole and the reflector is about 1/4 wavelength.

With such a structure, when excited by the central conductor 4a of the coaxial line 4 attached to the central portion of the metal disc 1, circular polarization of 90 ° phase is obtained by the dipole array.

FIG. 3 shows a modified example in which the dielectric body of FIG. 1 is formed by laminating two dielectric bodies 2a and 2b having different permittivities. The dielectric constant of the dielectric 2a is made large, and the electric field of the surface wave is made to follow the bottom surface as much as possible to control the coupling with the dipole layer DL.

FIG. 4 shows a modified example in which the dielectric 2c and the highly foamed dielectric 2d are combined, and the coupling ratio between the electric field of the surface wave and the dipole array DL can be controlled. ..

Needless to say, it is economically preferable to control the coupling rate with one dielectric plate.

FIG. 5 shows a modified example in which a slow wave circuit is constructed by using, as a dielectric, a pseudo dielectric made of a corrugated plate 2e in which a large number of concentric corrugations are formed on a metal plate. The corrugated plate 2e may be formed by directly processing a metal plate, or may be formed by laminating, vapor depositing or plating a metal foil on a plastic plate.

Then, a dielectric 2f for supporting the dipole layer DL which forms a radiation layer on the upper surface of the corrugated plate 2e.
Is arranged, and the radome 5 made of foam is attached to the outside thereof to reduce the influence from the outside.

FIG. 6 shows a case in which the structure of FIG. 5 has a weatherproof radome cover structure.

FIG. 7 shows an array of dipoles for generating circularly polarized waves, where the center of the radiation surface is the origin of the XY coordinates and the angle between the X axis and any radial axis on the radiation surface is defined. θ (in radians, θ is not limited to 0 ≦ θ ≦ 2π) and δ is an arbitrary number,

[Number 1] r = δ ± λg (θ / 2π) on al line R ₂ represented by Expression 1, dipole columns of C-shaped dipole 3,3 as shown in Figure 8 for each [pi / 2 When the starting point is (a),
(B) is 1/4 wavelength behind (b) and the vector is 90
° In-phase circularly polarized waves are generated because of the phase difference of the current due to the difference and distance. The same applies to points (c), (d), and (e).

In this way, a circularly polarized wave can be obtained by arranging the V-shaped dipoles at arbitrary positions on the helix R ₂ .
FIG. 8 shows examples of radiating elements having various arrangements other than the general C-shaped arrangement.

Next, in the structure shown in FIGS. 9 to 12, the dipoles 3 are arranged in two layers (or multiple layers) instead of arranging the dipoles 3 in the radial direction to form a V-shaped dipole array. The upper and lower dipoles form a cross (including X-shaped) dipole array.

That is, in FIG. 9, the lower dielectric 2g
One dipole 3a is on the upper side, and the upper dielectric 2h is on the other side.
(This dielectric 2h has an electrical thickness of about 1/4 wavelength), and the other dipoles 3b are mounted on the dipoles 3a and 3b as shown in FIG. C-shaped dipole rows (including X-shaped dipole rows) are formed.

Then, as shown in FIG. 11, the dipoles are arranged on the same line R ₂ as in FIG. 7 as a whole.

In the case of this example, even if excitation is performed in the same phase, there is a phase difference of 1/4 wavelength between the orthogonal dipoles 3a and 3b, so that circular polarization can be obtained.

In order to excite the upper and lower dipoles 3a and 3b with the same currents iu and id, the coupling degrees are changed by changing the angles θ ₁ and θ ₂ with respect to the radial direction. Can be achieved and circular polarization is obtained.

Although circularly polarized waves can be generated by changing the lengths of dipoles that are orthogonal to each other on the same plane, the length of the dipoles can be changed to control the amount of coupling with the electric field and obtain uniform radiation. Not suitable when taking the method. When the radial angle θ of the dipole is changed to suppress the coupling amount and the radiation amount of the dipole, the restrictions on the design on the same plane and the design on the upper and lower multilayer planes become relatively loose.

In FIG. 12, since the electric field is stronger closer to the metal plate, the dipole 3a is supplied roughly, and therefore the angle θ ₁ with respect to the radial direction (r direction) is increased, and the _one farther from the metal plate is supplied. Since the electric field is weak, a tight coupling with the dipole 3b is required, and therefore the angle θ ₂ with respect to the radial direction is reduced.

When using dipoles on the same plane,
As shown by the directivity curve 8 in FIG. 13, the directivity of the circularly polarized dipole is not the same in the radial direction in the case of circularly polarized wave by the dipole array in the V shape in the same plane. Although there is directivity in the (r direction) and the gain is slightly reduced, when the upper and lower dipoles are used, the directivity of the dipoles is circularly polarized at the same point as shown by the directivity curve 9 in FIG. As a result, the directivity is provided in the radiation direction, the gain is increased, and the side lobe can be reduced.

Further, when constructing a linearly polarized array antenna as shown in FIG. 15, the dipoles 3 are arranged in semicircles on concentric circles R4 to R8, and power is fed to generate a phase difference of left and right half wavelengths. The radiated electric fields can be in phase. In addition, the slow wave characteristic of the array antenna with the slots arranged in a H-shape has a characteristic of becoming slower as the frequency shifts to a higher frequency before and after the resonance characteristic of the slot, whereas the dipole array antenna has a rather high frequency. Accordingly, since the slow wave rate tends to decrease (not to be delayed), the phase between slots is compensated and the frequency band is widened, so that a wide band antenna can be obtained.

This will be described in more detail. Generally, in the case of a slot, the change in the slow wave rate due to the frequency characteristic of the slot becomes worse as the frequency changes, as shown in FIG. 16 (b). Change in direction. For example, when the frequency becomes higher, it becomes more and more inductive in the used frequency range and the degree of being delayed becomes greater. Further, since the slot interval is constant, when the frequency becomes high, a phase shift Δθ occurs due to the frequency change Δf, and the phase shifts to deteriorate the characteristics. When the slot is used in this way, double frequency characteristic deterioration occurs, and as a result, the frequency characteristic deteriorates in the form of a product. Generally, with a traveling waveform antenna, the frequency change Δ
The phase change [equation 2] with f is

[Equation 2] Naturally, the key to wideband antennas is how to solve this point.

On the other hand, when using a dipole antenna
As shown in 16 (a), the vicinity of the resonance is used, and the reactance approaches 0 at the frequency lower than the resonance, so that the capacitive current rapidly increases, and when the resistance component is ignored, [Equation 3]
Becomes a formula,

## EQU00003 ## i _C = -j.infinity Further, just after the resonance, the inductive current abruptly increases and becomes the equation [4].

Equation 4 The value of i _L = + j∞ induced current and past this decreases, showing a so-called resonance characteristics. Therefore, in the range excluding only the resonance part of the resonance characteristic, the phase has a characteristic of further advancing as the frequency becomes higher. As a result, as the frequency becomes higher, it is possible to obtain an antenna having the effect of compensating for the phase delay [Formula 2] that occurs and having wide-band characteristics.

In addition to the above-mentioned central feeding structure, the feeding structure may be a two-layer structure from the outside as shown in FIG. 17 (reference numeral 7 in FIG. 17 indicates a matching body). 18), and the spiral line on which the dipole array is arranged is a deformed spiral line R ₃ as shown in FIG. 18, so that the array antenna itself is set vertically (or horizontally) and transmitted / received to / from the satellite. Can be performed (the arrow in the figure indicates the propagation direction of the radio wave), in which case the array antenna can be set vertically or horizontally to avoid problems with the wind and snow of the array antenna. You can

[0034]

As described above in detail, according to the surface acoustic wave line array antenna of the present invention, it is compact and has a small loss, and it can be configured with a flat surface to reduce wind and snow damage.
Unlike the conventional array antenna, the radiation surface is not a metal plate but a dipole, so a broadband antenna can be obtained.
In addition, practical effects such as easy manufacture and lower manufacturing cost can be achieved.

[Brief description of drawings]

FIG. 1 is a plan view of a surface acoustic wave line array antenna as a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

[Figure 3]

[Figure 4]

[Figure 5]

6 is a cross-sectional view similar to FIG. 2 of a modified example.

FIG. 7 is a plan view showing an example of arrangement of dipoles.

FIG. 8 is a plan view showing another example of disposition of dipoles in an enlarged manner.

FIG. 9 is a lateral cross-sectional view of a main part of a surface acoustic wave line array antenna as a second embodiment of the present invention.

FIG. 10 is a schematic perspective view of the relevant part.

FIG. 11 is a plan view of the same.

FIG. 12 is a schematic plan view for explaining the same operation.

[Fig. 13]

FIG. 14 is a schematic side sectional view for explaining directivity.

FIG. 15 is an explanatory diagram of a linear polarization array antenna.

FIG. 16 (a) is an explanatory diagram of frequency characteristics of slow wave rate of the dipole array antenna of the present invention.

FIG. 16 (b) is an explanatory diagram of frequency characteristics of slow wave rate of the conventional slot array antenna.

FIG. 17 is a side sectional view of an array antenna showing a modified example of the power feeding method.

FIG. 18 is a perspective view showing a modified example of a helix.

FIG. 19 is a perspective view of a gobo line.

FIG. 20 is a schematic perspective view for explaining the principle of the present invention.

FIG. 21 is a side sectional view of the power feeding unit.

[Explanation of symbols] 1 Metal disk 2,2a, 2b, 2c, 2d, 2f, 2g, 2h Dielectric 2e Corrugated plate 3,3a, 3b Dipole 4 Coaxial line 4a Center conductor 5 Radome 8 and 9 Directional curve R ₁ , R ₂ , R ₃ etc. wire DL dipole constellation iu, id current

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[Procedure amendment]

[Submission date] October 9, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a plan view of a surface acoustic wave line array antenna as a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view similar to FIG. 2 of a modified example.

FIG. 4 is a sectional view similar to FIG. 2 of a modified example.

5 is a sectional view similar to FIG. 2 of a modified example.

FIG. 6 is a sectional view similar to FIG. 2 of a modified example.

FIG. 7 is a plan view showing an example of arrangement of dipoles.

FIG. 8 is a plan view showing another example of disposition of dipoles in an enlarged manner.

FIG. 9 is a lateral cross-sectional view of a main part of a surface acoustic wave line array antenna as a second embodiment of the present invention.

FIG. 10 is a schematic perspective view of the relevant part.

FIG. 11 is a plan view of the same.

FIG. 12 is a schematic plan view for explaining the same operation.

FIG. 13 is a schematic side sectional view for explaining directivity.

FIG. 14 is a schematic side sectional view for explaining directivity.

FIG. 15 is an explanatory diagram of a linear polarization array antenna.

16 (a) is an explanatory diagram of frequency characteristics of slow wave rate of the dipole array antenna of the present invention. FIG. (B) It is explanatory drawing of the frequency characteristic of the slow wave rate of the conventional slot array antenna.

FIG. 17 is a side sectional view of an array antenna showing a modified example of the feeding system.

FIG. 18 is a perspective view showing a modified example of a helix.

FIG. 19 is a perspective view of a gobo line.

FIG. 20 is a schematic perspective view for explaining the principle of the present invention.

FIG. 21 is a side sectional view of the power feeding section.

[Explanation of reference numerals] 1 metal disk 2, 2a, 2b, 2c, 2d, 2f, 2g, 2h dielectric 2e call gate plate 3, 3a, 3b dipole 4 coaxial line 4a center conductor 5 radome 8 and 9 directivity curve R ₁ , R ₂ , R ₃ Wires DL Dipole constellation iu, id Current

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 8]

[Figure 9]

[Fig. 12]

FIG. 21

[Figure 7]

[Figure 10]

FIG. 11

[Fig. 13]

FIG. 14

FIG. 15

FIG. 17

FIG. 18

FIG. 19

FIG. 20

FIG. 16

Claims (2)

[Claims] 1. A slow-wave circuit made of a dielectric or pseudo-dielectric is provided on one metal plate, and a mode in which a radial current flows almost radially on the metal plate is used, and this surface is used. A surface wave propagating in the radial direction is excited by an electric field excited in a direction orthogonal to and parallel to, and the dipole row excited by this surface wave is arranged almost parallel to the metal surface, and the direction almost orthogonal to this dipole row. A surface wave line array antenna with the function of radiating or receiving circularly or linearly polarized waves. 2. A slow wave circuit made of a dielectric material or a pseudo dielectric material is provided on a single metal plate, and a mode in which a radial current flows almost radially on the metal plate is used, and this surface is used. A surface wave propagating in the radial direction is excited by an electric field that is excited in a direction perpendicular to and parallel to, and the dipole array excited by this surface wave is arranged in a spiral shape substantially parallel to the metal surface. A surface wave line array antenna with the function of radiating or receiving circularly polarized waves in orthogonal directions.