JPH0720011B2 - Circular polarization modified beam antenna - Google Patents

Description

TECHNICAL FIELD The present invention relates to a circular polarized wave modified beam antenna used in various radars.

(Prior Art) In a radar that searches for a target on the ground, at sea, or in the air, in order to improve the azimuth resolution, the horizontal beam is made narrow and the vertical beam makes the reception level of the reflected wave from the target constant regardless of the distance. For this reason, a deformed beam having a characteristic of cosec ² θ in a wide range of angles θ in the vertical plane may be used.

Further, the above radar may use circular polarization in order to reduce the influence of reflected waves from raindrops when it rains. In such a case, in order to effectively reduce the reflected wave from the raindrop, it is necessary that the circular polarization is maintained over a relatively wide range of angles reached by the modified beam.

Documents describing conventional circularly polarized beam modified beam antennas include: (1) Mizusawa, et al. 4 "Double-curve double-repeating mirror antenna for circularly polarized waves", IEICE, Aerospace Electronics Research Group, Material No. A. , P74-81, p25-32.

(2) Xie, 3 others “Design and radiation characteristics of H-plane fan-shaped cosecant beam horn antenna with dielectric insertion”, IEICE Transactions, '82 / 10 Vol.J-65B, No.10, p1221-1228 .

Etc.

FIG. 7a shows a basic structure of a conventional circular polarized wave modified beam antenna, which is composed of a primary horn 1 and a parabolic reflector 2 and deforms a fan beam on a vertical plane to obtain a cosec ² θ characteristic. The upper part of the parabolic reflector 2 is modified so that a beam pattern can be obtained.

In FIG. 7a, L ₁ , L ₂ , and L ₃ indicate the traveling direction of the radio wave (when operating as a transmitting antenna. The same applies below). The radio wave traveling direction is changed by deforming the upper part of the parabolic reflector. Change the direction to L ₂ and L ₃ and cose the beam in the vertical plane
c ² θ characteristic pattern. Further, C ₁ and C ₂ show directivities of the primary horn with respect to horizontal polarization and vertical polarization. Since the primary horn is a rectangular aperture horn, horizontal polarization and vertical polarization in the aperture plane And the directivity for both polarizations is different.

FIG. 7b is a cross-sectional view of a circularly polarized wave modified beam antenna similar to that disclosed in the above-mentioned document (1).
It is composed of a next horn 3, a sub-reflecting mirror 4, and a main reflecting mirror 5. L ₄ , L ₅ , and L ₆ indicate the traveling directions of radio waves.

This antenna uses a conical horn as the primary horn, and has a special curved main and sub reflecting mirror to make
A modified beam having a sec ² θ characteristic is formed, and circularly polarized waves can be obtained within a predetermined angle range of the modified beam.

FIG. 8 shows a modified beam antenna disclosed in the above reference (2) in which a dielectric 8 is inserted into a fan horn 7 to obtain a modified beam having a cosec ² θ characteristic. Although the opening surface of is a special curved surface, the distribution of both polarized waves on the opening surface is different because the propagation attitudes of the horizontally polarized wave and the vertically polarized wave in the fan-shaped horn are different. .

(Problems to be Solved by the Invention) However, among the conventional modified beam antennas shown in FIG. 7a, the directivity of the primary horn for horizontal polarization and vertical polarization is different, so A specific angular orientation (eg horizontal) within the modified beam when polarized
However, there is a problem that the circular polarization cannot be obtained because the amplitude relationship between the horizontal and vertical polarizations becomes different in other angle directions.

Further, in the case shown in FIG. 7b, since the main reflecting mirror and the sub-reflecting mirror need to be finished to have special curved surfaces, it is difficult to secure manufacturing accuracy because high special technology is required for designing and manufacturing.
There is a problem that it is difficult to obtain a good directivity and the manufacturing cost increases.

Further, the antenna shown in FIG. 8 has a different distribution of both polarized waves on the aperture plane because the propagation states of the horizontal polarized wave and the vertical polarized wave are different in the fan-shaped horn, and is similar to the antenna shown in FIG. 7a. In addition, there is a problem that circularly polarized waves cannot be obtained within a predetermined angle range of the deformed beam.

The present invention eliminates the above-mentioned drawbacks of the conventional antenna, and within the predetermined angle range of the modified beam, circular polarization is obtained,
Another object is to provide a circularly polarized modified beam antenna that is easy to design and manufacture and inexpensive.

(Means for Solving the Problems) The present invention relates to an antenna composed of a primary horn and a parabolic cylinder type reflecting mirror, in which a lower plane plate of the antenna is horizontal in front of the parabolic cylinder type reflecting mirror, When the opening surface is the front surface, in the vertical direction along the opening surface perpendicular to the horizontal plane, the thickness from the rear end parallel to the opening surface toward the opening surface is desired at each point in the vertical direction of the opening surface. A dielectric plate having a constant thickness is provided in the vertical direction along the aperture plane and in a direction orthogonal to the main radiation direction, and the waveguide plate is provided on the input side of the primary horn. A circularly polarized wave generator and a waveguide type phase shifter are provided.

(Operation) The circular polarized wave modified beam antenna of the present invention is a waveguide circular polarized wave generator and a waveguide type antenna provided on the input side of the primary horn of the antenna composed of the primary horn and the parabolic cylinder type reflecting mirror. A phase shifter is provided to obtain circularly polarized radio waves, and a dielectric plate having a special cross section is provided in front of the parabolic cylinder type reflecting mirror to refract a part of the radio waves emitted from the parabolic cylinder type reflecting mirror. Thus, a circularly polarized beam having a cosec ² θ characteristic is formed. The dielectric has a specific permittivity e, the velocity v of the radio wave propagating in the dielectric is smaller than the velocity c of the radio wave propagating in free space, and the relative refractive index is Causes the radio wave to be refracted at the interface between the dielectric and free space. Therefore, the cross-sectional shape of the dielectric plate is a flat inside,
By gently curving the outside in the vertical direction and continuously changing the thickness of the dielectric, when a radio wave incident from the inside of the dielectric plate at a right angle is radiated into the free space after passing through the dielectric, Since the traveling direction is diffused along the curve of the surface of the dielectric plate, a desired deformed beam can be obtained by selecting the shape of the curve. The circularly polarized wave is divided into two distributions of equal amplitude by the waveguide type circularly polarized wave generator, and the linearly polarized wave having a main electric field component in the vertical direction is divided by the waveguide type phase shifter. It is obtained by adjusting the phase change that two component forces undergo until they are radiated into free space.

(Embodiment) FIG. 1 is a drawing related to an embodiment of the present invention. FIG. 1A is a plan view, FIG. 1B is a side view, FIG. 1C is a sectional view taken along the line AA of FIG. 1A, and FIG. 1D. FIG. 3 is a perspective view of FIG.

In FIG. 1 a, b, c, d, 10 is a parabolic cylinder type reflecting mirror, 11 is an upper plane plate, 12 is a lower plane plate, the upper plane plate 11 and the lower plane plate 12 are parallel, and are parabolic cylinder type. It is perpendicular to the focal axis F of the reflecting mirror 10.

Reference numeral 13 denotes a primary horn, the opening of which is placed in the vicinity of the focal axis F and serves as a line source for the parabolic cylinder type reflecting mirror 10. Parabolic cylinder type reflector 10, upper flat plate 11, lower flat plate 12 and primary horn
13 and so-called cheese antenna.

Reference numeral 14 in FIGS. 1a and 1c is a dielectric plate, which is the main emission direction of the radio wave (first
The thickness in the direction orthogonal to the opening surface 22 in FIG. C) changes in the direction of the focal axis F, and has a constant shape in the direction perpendicular to the main radiation direction and the focal axis F (lateral direction in FIG. 1a). And acts to form a deformed beam.

In FIG. 1b, reference numeral 15 is a conversion waveguide, the input side is a standard rectangular shape, the output side is a circular shape, and the space between the input side and the output side gradually changes from a rectangular shape to a circular shape. There is.

Reference numeral 16 is a waveguide type circularly polarized wave generator, and the vertical direction input from the conversion waveguide 15 (the vertical direction in FIG. 1b is the vertical direction, and the direction orthogonal to the plane of the drawing is the horizontal direction. ) Receives a circular TE ₁₁ mode radio wave with a main electric field component, and the electric field is equal in two directions orthogonal to the output side, and the phase is 90 °.
It generates circular TE ₁₁ mode radio waves consisting of different two-component forces, that is, circularly polarized waves in a circular waveguide. Reference numeral 17 denotes a waveguide type phase shifter, which receives the circularly polarized wave from the waveguide type circularly polarized wave generator 16 and delays the phase of the polarized wave component in the vertical direction of the electromagnetic wave and outputs it.
Reference numerals 18 and 20 denote conversion waveguides, respectively, for the difference in the waveguide cross-sectional shape between the special waveguide 19 and the waveguide type phase shifter 17, and between the special waveguide 19 and the curved waveguide 21. The cross-sectional shape is gradually changed inside to convert the cross-sectional shape of the waveguide between the input and the output. The cross section of the special waveguide 19 has a rectangular shape of a special size, and serves to reduce the rate at which the phase difference between the two component forces forming the circularly polarized radio wave radiated from this antenna changes due to frequency changes. do. The curved waveguide 21 has a square cross section. Reference numeral 22 is the opening surface of the antenna.

Fig. 2 is a cross-sectional view of the waveguide type circularly polarized wave generator 16 and a plane orthogonal to the tube axis. E is the central electric field vector of the input circular TE ₁₁ mode radio wave, and 16a in the figure is the dielectric plate. And the electric field vector E
Direction (vertical direction) is inclined at 45 ° and extends long in the tube axis direction, and both ends are tapered so as to reduce the reflection of radio waves, and the length in the tube axis direction is appropriately selected. Circularly polarized radio waves in the circular waveguide are generated on the output side so that the phase difference between the polarized component in the same direction as the polarized component and the polarized component in the direction orthogonal thereto becomes 90 °.

FIG. 3 is a cross-sectional view of a plane orthogonal to the tube axis of the waveguide type phase shifter 17, in which a dielectric plate is vertically arranged in a circular waveguide of the same size as the waveguide type circularly polarized wave generator 16. 17a is placed. The dielectric plate 17a has a length in the tube axis direction, and both ends thereof are tapered to reduce reflection of radio waves.

4 is a drawing relating to the primary horn 13, FIG. 4a is a side view, and FIG. 4b is a sectional view taken along line BB of FIG. 4a. In FIG. 4a, 13a is a parabolic cylinder type reflecting surface of the primary horn 13, 13b is an input horn, 13c is an opening surface of the primary horn 13,
G is the focal axis of the reflecting surface 13a, K is the opening surface of the input horn 13b, and the opening surface K is near the focal axis G. L ₁₀ is the maximum radiation direction of the primary horn 13 of the input horn 13b, and L ₁₁
L ₁₂ is the radiation direction from the input horn 13b to the lower end and the upper end of the reflecting surface 13a, respectively. The input surface of the input horn 13b has a square waveguide cross section.

In FIG. 4b, d ₁ is the distance between the parallel plates of the primary horn 13, and d ₂ is the opening width of the opening surface 13c.

FIG. 5 is a diagram for explaining refraction of radio waves by the dielectric plate 14
A cross section of the dielectric plate 14 in the same plane as the cross section of FIG. In FIG. 5, p is an arbitrary point on the curve w on the front surface of the dielectric plate 14, L ₂₁ is the direction of the input radio wave reaching the point p, and L ₂₂ is the radio wave that is refracted from the point p and radiated to the outside. Method, θ is the angle between direction L ₂₂ and direction L ₂₁ .

The operation of this embodiment will be described below with reference to FIGS. 1a, 1b, 1c, 2b, 3c, 4a, 5b and 5. Figure 1b
, A standard rectangular TE ₁₀ mode electric wave having a main electric field component in the vertical direction applied to the input side of the conversion waveguide 15 has a circular TE ₁₁ mode having a main electric field component in the vertical direction gradually in the conversion waveguide 13. It is converted to a mode and sent to the waveguide circular polarization generator 16 and the circular T
E ₁₁ mode circularly polarized radio wave. I.e. two orthogonal
Two circular TE ₁₁ mode radio waves in which the amplitudes of the electric field components in the directions are the same and the phases are different by 90 °. Circularly polarized radio waves cross at right angles 2
Since the directions of the components may be arbitrarily selected, the vertical direction and the horizontal direction will be taken in the following description. Circularly polarized TE _11- mode circularly polarized wave output from the waveguide circularly polarized wave generator 16 is sent to the waveguide type phase shifter 17, where the main electric field component becomes vertical due to the action of the dielectric plate 17a. The radio wave in the direction undergoes a phase change more than the radio wave in the horizontal direction, and is transmitted to the conversion waveguide 18 as two radio waves in which the amplitude of the main electric field component is equal in the vertical and horizontal directions. In the conversion waveguide, this 2
Each of the two radio waves gradually changes from circular TE ₁₁ mode to rectangular TE ₁₀ mode (mode with electric field in the vertical direction) and rectangular TE ₀₁ mode (mode with electric field in the horizontal direction). Is transmitted to the special waveguide 19. In the special waveguide 19, the radio waves of the two rectangular modes undergo phase changes due to propagation in accordance with the horizontal and vertical widths of the special waveguide 19, respectively, and are sent to the conversion waveguide 20. 2 above
The radio waves of the one rectangular mode are in the same mode, propagate in the conversion waveguide 20 that gradually changes from rectangular to square, are sent to the curved waveguide 21, and propagate in the curved waveguide as they are.
Next sent to horn 13. As is clear from the above description, the two rectangular mode radio waves applied to the primary horn 13 are rectangular TE ₁₀ mode radio waves having an electric field in the direction perpendicular to the propagation direction and the horizontal direction, and the horizontal direction. Rectangular with electric field at TE ₀₁
In the mode radio waves, the amplitudes of both radio waves are equal, and the phases differ by a certain value according to the propagation until reaching the primary horn 13. The two radio waves propagate in the input horn 13b of the primary horn 13 and are radiated from the opening surface K of the input horn 13b toward the reflecting surface 13a. The electric field distribution on the opening surface K is calculated from the two electric waves applied to the primary horn 13,
For a radio wave having an electric field component in a direction perpendicular to the propagation direction and the horizontal direction (hereinafter, such a radio wave is referred to as vertically polarized wave), the amplitude is almost cosine distribution, the phase is uniform, and the focus is in the focus axis G direction. The amplitude is almost uniform in the direction orthogonal to the axis G, and the phase has a square characteristic that is slightly delayed at both ends of the opening surface K, and the primary horn
Of the two radio waves applied to 13, a radio wave having an electric field distribution in the horizontal direction (hereinafter, such a radio wave is referred to as horizontal polarized wave) is uniform in both amplitude and phase in the direction of the focal axis G and In the direction orthogonal to the axis G, the amplitude has a substantially cosine distribution, and the phase has a square characteristic that is slightly delayed at both ends of the opening surface K. On the aperture plane K, two radio waves of vertical polarized wave and horizontal polarized wave having the above electric field distribution are radiated between the parallel plates of the primary horn 13, but the plane parallel to the parallel plates. Considering the radiation directivity, since the vertical polarization has a uniform electric field distribution in the direction orthogonal to the focal axis G on the aperture plane K, the directivity spreads in the direction of horizontal polarization in terms of the aperture distribution. However, the wavelength in the parallel plate of vertical polarization (λ
g) is longer than the free space wavelength (λ) On the other hand, since the wavelength of the horizontally polarized wave in the parallel plate is substantially equal to the free space wavelength because the shape of the primary horn 13 is sufficiently larger than the free space wavelength, it is vertical from the viewpoint of the wavelength in the parallel plate. The directivity of polarized waves has a factor of becoming wider than that of horizontal polarized waves, and as a result, the parallel plate spacing d ₁
By properly selecting, it is possible to make the radiation directivity spread in the parallel plate of vertical polarization and horizontal polarization almost equal.

The level radiated from the input horn 13b in the directions L ₁₁ and L ₁₂ is usually selected to be 10 dB lower or higher than that in the direction L ₁₀ . since in order to satisfy the best to select about 0.68 the value of d ₁ / lambda was found from the study of the directivity, in this embodiment d ₁
The value of / λ is chosen as above. Therefore, the amplitude of the electric field on the opening surface 13c of the primary horn 13 is substantially equal at the upper end of the opening surface 13c for the vertically polarized wave and the horizontally polarized wave.
Due to the nature of the parabolic surface of the reflecting surface 13a, the phase of the electric field on the opening surface 13c is uniform with respect to vertical polarization and horizontal polarization. The amplitude of the electric field between the upper end and the lower end of the opening surface 13c is completely equal to the vertical polarization and the horizontal polarization because the radiation directivity functions for the vertical polarization and the horizontal polarization of the input horn 13b are different. No, but they are almost equal. Opening surface
The electric field distribution in the direction of the focal axis G of 13c is the same as the distribution on the aperture plane K, and the amplitude is cosine distribution, the phase is uniform for vertical polarization, and the amplitude and phase are uniform for horizontal polarization. Has become. The vertically polarized and horizontally polarized electric fields on the aperture plane 13c are radiated as a cylindrical wave toward the parabolic cylinder type reflecting mirror 10, and are reflected by the reflecting mirror 10 to become a plane wave, which is placed on the aperture plane 22 of the present antenna. Incident on the dielectric plate 14.

The opening width d ₂ of the primary horn 13 is different from the parallel plate spacing d ₁
When two radio waves of vertically polarized wave and horizontally polarized wave are radiated from the aperture plane 13c, the radiation level of the parabolic cylinder type reflecting mirror 10 toward both end directions of the paraboloid is lowered from the maximum radiation level at the center by a predetermined value. This is because. This predetermined value is usually selected to be about 10 dB lower, but in order to satisfy this condition for vertically polarized waves and horizontally polarized waves, the angle at which both end directions of the paraboloid are viewed from the focal axis F is about 80. ° × 2 = 160 °
It was found from the examination of the directivity that the value of d ₂ / λ should be about 0.62. Therefore, the distribution of the electric field in the horizontal direction of the plane wave immediately before entering the dielectric plate 14 is substantially equal at both ends with respect to the vertically polarized wave and the horizontally polarized wave, and in the middle, radiation in the plane orthogonal to the focal axis G of the primary horn 13 is generated. Since the directivity functions are different for vertical and horizontal polarization, they are not exactly equal for both polarizations, but they are almost equal. On the other hand, the electric field distribution for both polarizations of the plane wave in the vertical direction is a primary horn because the distance between the plane plate 11 and the lower plane plate 12 is sufficiently larger than the wavelength.
The electric field distribution for both polarizations in the vertical direction on the aperture plane 13c of 13 is almost equal. Therefore, the electric field distribution of the plane wave in the vertical direction is substantially equal for both polarized waves. After all, the amplitude of the electric field of the plane wave incident on the dielectric plate 14 is substantially equal to each other in the vertical polarization and the horizontal polarization both in the horizontal direction and the vertical direction.

Since the plane waves of the vertically polarized waves and the horizontally polarized waves are vertically incident on the dielectric plate 14, both the radio waves of both polarizations go straight in the dielectric plate 14 and reach the front curve w. Here, the radio waves of both polarizations are refracted by the dielectric material, and their traveling directions can be changed in a vertical plane orthogonal to the aperture plane 22.
For example, in FIG. 5, the radio wave traveling in the direction L ₂₁ and reaching the point p is directed downward at the point p by the angle θ from the direction L _{21 in} the direction L _22.
Can be changed to Since the angle θ due to this refraction depends on the inclination of the curve w with respect to the vertical, the vertical directivity can be modified by the shape of the curve w. (The method of determining the curve w is described in Japanese Patent Application No. 61-04638 "Circularly polarized wave modified beam antenna".) When the above-mentioned vertically polarized and horizontally polarized plane waves enter the dielectric plate 14, some reflection occurs. However, this reflection amount is equal for both polarized waves because of normal incidence. Also, when the radio waves of both polarizations are radiated to the outside from the boundary forming the curve w, some reflection occurs at this boundary. However, when the inclination of the curve w with respect to the vertical is not so large, both reflections are polarized. Almost equal to the waves. Furthermore, the absorption loss in the dielectric plate 14 is also equal for both polarized waves. Therefore, the relative relationship of the amplitudes of the electric fields of both polarizations outside the boundary is equal to the relative relationship of the amplitudes at the corresponding incident points on the dielectric plate 14. That is, the amplitudes of the electric fields of both polarizations outside the boundary are substantially equal to each other at any position in the horizontal direction and the vertical direction. Therefore, the electric field amplitudes of vertically polarized waves and horizontally polarized waves at each distant point of the radio wave radiated in each direction from each point of the boundary are almost equal to each other when the angle of radiation from the horizontal plane is not so large. become.

Next, the relative relationship between the phases of the vertically polarized electric field and the horizontally polarized electric field at the distant points will be described. Since the relative relationship between the phases of both the polarized waves in the vertical and horizontal directions does not change in the propagation inside the dielectric plate 14 and the propagation in the external space, the relative relationship between the phases of the polarized waves at the distant points is the dielectric plate. Equal to the relative phase relationship of both polarizations of the plane wave incident on 14. The relative relationship of the phases can be changed by the length of the dielectric plate 17a of the waveguide type phase shifter 17 in the tube axis direction. Therefore, the length of the dielectric plate 17a in the tube axis direction is set so that the phase of the vertical polarization of the plane wave incident on the dielectric plate 14 may be advanced or delayed by 90 ° with respect to the horizontal polarization depending on the required circular polarization rotation direction. By changing the above, it is possible to satisfy the condition necessary for obtaining the circularly polarized wave in the phase relative relationship between the two polarized waves at each of the distant points, and the amplitudes of the two polarized waves are almost equal because of the above description. It is possible to obtain almost circularly polarized waves within the angular range of the modified beam. However, the phase relationship between the two polarized waves from which the circularly polarized wave is obtained is satisfied exactly at only one frequency, and when the frequency changes, the phase difference between the two polarized waves also changes. Especially the primary horn
Within 13, the guide wavelength for vertically polarized waves is longer than the guide wavelength for horizontally polarized waves, so the change in the phase difference becomes large when the frequency changes. The special waveguide 19 reduces this effect,
In the waveguide 19, the vertical width of the rectangular waveguide cross section is set to the horizontal width (the side perpendicular to the paper surface in FIG. 1b so that the vertical polarization internal wavelength is shorter than the horizontal polarization internal wavelength. The length of the primary horn 13 is opposite to the change in the phase difference between the two polarized waves when the frequency changes. The cross-sectional size and length of the special waveguide 19 are appropriately selected so that the change in the phase difference between the electric fields of the vertically polarized wave and the horizontally polarized wave at a distant point with respect to the frequency is not more than a predetermined value.

In the present embodiment, when the modified beam having the directivity of the cosec ² characteristic on only one side of the main beam is used, the shape of the curve w has an inclination with respect to the vertical direction corresponding to the main beam as shown in FIG. It has a loose upper part and a lower part with a large inclination to the vertical corresponding to the cosec ² characteristic.
In such a case, the removal of the upper portion does not have much relation to the directivity, so that this portion can be removed. FIG. 6a shows a cross section of the dielectric plate 14 with the upper part removed. Further, in this case, since the slope of the curve w changes gently, it can be approximated by a polygonal line. FIG. 6b shows the sectional shape of the dielectric plate 14 when the curve w of FIG. 6a is approximated by two polygonal lines N ₁ and N ₂ .

As described above, in the present invention, depending on the shape of the deformed beam, it is possible to reduce the number of dielectric portions provided in the vicinity of the aperture surface 22 of the antenna and to simplify the sectional shape of the dielectric plate 14.

(Effects of the Invention) As described in detail above, according to the present invention, in the antenna configured by the primary horn and the parabolic cylinder type reflecting mirror, the main part of the antenna is provided in front of the parabolic cylinder type reflecting mirror. The thickness in the radial direction changes along the direction of the focal axis of the parabolic cylinder type reflecting mirror, and the dielectric plate having the constant thickness is provided in the direction orthogonal to the focal axis and the main radial direction. By providing a waveguide circular polarization generator and a waveguide phase shifter on the incident side of the primary horn, almost circular polarization can be obtained within a predetermined angle range of the modified beam, and Since the dielectric plate has a uniform cross-sectional shape, it is easy to design and manufacture, and the manufacturing cost is low. Further, depending on the shape of the required deformed beam, the number of dielectric parts can be reduced, and the cross-sectional shape of the dielectric plate can be significantly simplified, which makes designing and manufacturing extremely easy and can provide an inexpensive circular polarized wave deformable beam antenna. Therefore, it is effective when applied to various radars that search for targets on the ground, at sea, or in the air.

[Brief description of drawings]

1a is a plan view of an embodiment of the present invention, FIG. 1b is a side view of FIG. 1a, FIG. 1c is a sectional view taken along line AA of FIG. 1a, and FIG.
Is a perspective view of FIG. 1a, FIG. 2 is a sectional view of a waveguide type circularly polarized wave generator, FIG. 3 is a sectional view of a waveguide type phase shifter, and FIG. 4a is a side surface of a primary horn. Fig. 4b is a BB sectional view of Fig. 4a,
FIG. 5 is a diagram for explaining refraction of radio waves by the dielectric plate 14, FIG. 6a
Is a cross-sectional view of the dielectric plate 14 as an example 1, and FIG.
2 is a cross-sectional view of Example 1 of a conventional circular polarization modified beam antenna, and FIG. 7b is a cross-sectional view of Example 2 of a conventional circular polarization modified beam antenna, and FIG. FIG. 6 is a perspective view of an example of a conventional modified beam antenna. 1 ... primary horn, 2 ... parabolic reflector, 3 ... primary horn, 4 ... sub-reflector, 5 ... main reflector, 7 ... fan-shaped horn, 8 ... dielectric, 10 ... Parabolic cylinder type reflector, 11 …… Top plane plate, 12 …… Bottom plane plate, 13 ……
Primary horn, 13a ... Reflecting surface, 13b ... Input horn, 13c
...... Aperture surface, 14 ...... Dielectric plate, 15,18,20 …… Conversion waveguide, 16 …… Waveguide circular polarization generator, 16a, 17a …… Dielectric plate, 17 …… Conduction Wave tube type phase shifter, 19 …… Special waveguide, 21 ……
Curved waveguide, 22 ... Opening surface.

Claims (2)

[Claims] 1. An antenna comprising a primary horn and a parabolic cylinder type reflecting mirror, wherein when the lower plane plate of the antenna is horizontal and the opening surface is the front surface, the antenna is along an opening surface perpendicular to a horizontal plane. In the vertical direction, the thickness from the rear end parallel to the aperture plane toward the aperture plane changes according to the desired beam direction at each point in the vertical direction of the aperture plane, and the vertical direction along the aperture plane and the main radiation direction In the direction orthogonal to and, a dielectric plate having a constant thickness is provided in front of the parabolic cylinder type reflecting mirror, and a waveguide type circular polarization generator and a waveguide type phase shifter are provided. A circular polarized wave modified beam antenna, which is provided on the input side of a primary horn. 2. The circularly polarized wave modified beam antenna according to claim 1, wherein a cheese antenna is used as an antenna composed of the primary horn and a parabolic cylinder type reflecting mirror.