JP2624053B2 - Dual frequency antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual-frequency antenna device comprising a primary reflector, a secondary reflector and two primary radiators used in a microwave band.

[0002]

2. Description of the Related Art FIG. 4 is an example of a sectional view of a conventional dual-frequency antenna device. In the figure, 1 is a primary radiator, 2 is a sub-reflection mirror, 3 is a main reflection mirror, 4 is an axis of rotational symmetry, and 5 is an aperture surface. FIG. 5 shows an example of a primary radiator of a conventional dual-frequency antenna device. In the figure, reference numerals 1a and 1b denote primary radiators in different frequency bands, respectively, and reference numeral 15 denotes a sub-reflector focal point.

Next, the operation will be described. Rotational symmetry axis 4
The main reflector 3 is usually a parabola and the sub-reflector 2 is hyperbolic or elliptical in any cross section including Two primary radiators 1a, 1 located on the focal point of a hyperbola or an ellipse
The spherical wave radiated from b is reflected in the order of the sub-reflecting mirror 2 and the main reflecting mirror 3, and is radiated as a plane wave in the direction of the aperture surface 5.

[0004]

Since the conventional dual-frequency antenna apparatus is constructed as described above, in order to place two primary radiators at the focal point of the sub-reflector, the primary radiator corresponding to the two frequencies is required. The radiator must be integrated, which complicates the configuration.Because the outer primary radiators must be spaced apart, the beam width of the primary radiators decreases and the spillover increases, resulting in lower antenna efficiency. I do. In addition, there is a problem that the side lobe of the radiation pattern of the primary radiator enters the main reflecting mirror and the side lobe rises.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a simplified structure of a primary radiator.
An object of the present invention is to obtain a dual-frequency antenna device having high efficiency and low side lobe characteristics at two frequencies.

[0006]

In the dual frequency antenna device according to the present invention, one primary radiator is arranged at the focal point of a main reflector and excited by vertical polarization, and the other primary radiator is sub-reflected. At the focal point of the mirror and excited with horizontal polarization,
A horizontal grid is placed on the sub-reflector whose arbitrary cross section including the rotational symmetry axis is a hyperbola or an ellipse, and a 45 ° grid is placed on the main reflector whose arbitrary cross section including the rotational symmetry axis is a parabola. Things.

In addition, one primary radiator is arranged at the focal point of the main reflector and excited by horizontal polarization, and the other primary radiator is arranged at the focal point of the sub-mirror and excited by vertical polarization. A vertical grid is placed on the sub-reflector whose arbitrary cross section including the rotational symmetry axis is a hyperbola or an ellipse, and a 45 ° grid is placed on the main reflector whose arbitrary cross section including the rotational symmetry axis is a parabola. Things.

[0008]

The dual-frequency antenna device according to the present invention comprises:
Place one primary radiator at the focal point of the main reflector and excite it with vertical polarization, place the other primary radiator at the focal point of the sub-reflector and excite it with horizontal polarization and include a rotationally symmetric axis Since the horizontal grid is arranged on the sub-reflector whose arbitrary cross section is hyperbolic or elliptical, and the 45 ° oblique grid is arranged on the main reflector whose arbitrary cross section including the rotational symmetry axis is parabolic, the primary radiator Can be separately arranged on the axis of rotational symmetry, so that the configuration of the primary radiator is simplified, and high efficiency and low side lobe antenna performance can be obtained.

[0009]

[Embodiment 1] FIG. 1 is a view showing an embodiment of the present invention, wherein 1b is a primary radiator arranged at a focal point of a main reflector and excited by vertical polarization, and 1a is arranged at a focal point of a sub-reflector 2 and horizontally polarized Primary radiator excited by, 6 is main reflector 3
An oblique 45 ° grid placed above, 7 is the axis of rotational symmetry 4
Is a horizontal grid arranged on the sub-reflecting mirror 2 having an arbitrary cross section including a hyperbola or an ellipse.

Next, the operation will be described. Primary radiator 1
Since the spherical wave radiated from a is excited by the horizontally polarized wave, the spherical wave is reflected by the sub-reflecting mirror 2 having the horizontal grid 7 and is blown to the main reflecting mirror 3.

FIG. 2 is a cross-sectional view of the main reflecting mirror, and FIG. 3 is a diagram showing reflection of radio waves on the main reflecting mirror. In the figure, 8
Is a conductor plate of the main reflector, 9 is an incident radio wave, 10 is a component orthogonal to the grid of the incident radio wave, 11 is a component parallel to the grid of the incident radio wave, 12 is a component orthogonal to the grid of the reflected radio wave, and 13 is a reflected radio wave. The component 14 parallel to the grid is a reflected radio wave. The radio wave incident on the main reflecting mirror with horizontal polarization is divided into a component parallel to the grid 6 and a component orthogonal thereto. The component parallel to the grid 6 is reflected by the grid 6 and the phase changes by 180 degrees. On the other hand, the component orthogonal to the grid 6 is transmitted and reflected by the conductor plate 8 of the main reflecting mirror. At this time, if the distance d between the grid 6 and the conductor plate 8 is determined as shown by the following equation, when the radio wave reflected by the conductor plate 8 reaches the grid surface, its phase becomes the same as that of the incident radio wave.

[0012]

(Equation 1)

Therefore, the radio wave reflected by the conductor plate 8 is combined with the radio wave reflected by the grid surface 6, and the polarization is changed by 90 degrees to be radiated as a vertically polarized plane wave. The radio wave changed to the vertically polarized wave reaches the sub-reflector 2, but the sub-reflector 2
The upper horizontal grid 7 is transmitted, becomes a plane wave, and is emitted in the direction of the opening surface.

On the other hand, since the spherical wave radiated from the primary radiator 1b placed at the focal point of the main reflecting mirror 3 is excited by a vertically polarized wave, the spherical wave passes through the sub-reflecting mirror 2 having the horizontal grid 7 and passes through the main reflecting mirror 2. It is sprayed on the reflecting mirror 3. The component of the radio wave incident on the main mirror that is parallel to the grid 6 is reflected by the grid 6 and changes in phase by 180 degrees. In addition, orthogonal components are transmitted.

Here, the frequency fa of the radio wave radiated from the primary radiator 1a and the frequency fb of the radio wave radiated from the primary radiator 1b are set as follows.

[0016]

(Equation 2)

In this case, the above “Equation 1” is as follows.

[0018]

(Equation 3)

In this case, a radio wave of a component orthogonal to the grid 6 that has passed through the grid 6 is reflected by the conductor plate 8 of the main reflector, but the radio wave reflected and reaching the grid surface changes by 180 degrees. Therefore, a radio wave radiated from the main reflecting mirror, which is radiated as a plane wave of the same vertically polarized light as when it is incident, passes through the sub-reflecting mirror 2 and is radiated in the direction of the opening surface.

As a result, the performance of the primary radiators 1a and 1b can be determined independently of each other, so that the configuration is simplified. Further, since there is no blocking of the sub-reflector, high efficiency and low side lobe characteristics can be obtained.

Embodiment 2 FIG. In the above embodiment,
Place one primary radiator at the focal point of the main reflector and excite it with vertical polarization, place the other primary radiator at the focal point of the sub-reflector and excite it with horizontal polarization and include a rotationally symmetric axis A case has been described where a horizontal grid is arranged on a sub-reflector whose arbitrary cross section is a hyperbola or an ellipse, and an oblique 45 ° grid is arranged on a main reflector whose arbitrary cross-section including a rotational symmetry axis is a parabola. , One primary radiator is placed at the focal point of the main reflector and excited with horizontal polarization, the other primary radiator is placed at the focal point of the sub-reflector and excited with vertical polarization, and the rotational symmetry axis is A vertical grid is arranged on a sub-reflector whose arbitrary cross section including a hyperbola or an ellipse is included.
The same effect can be obtained by arranging a 5 ° grid.

[0022]

As described above, according to the present invention, one primary radiator is disposed at the focal point of the main reflector and excited by vertical polarization, and the other primary radiator is disposed at the focal point of the sub-reflector. Excitation with horizontal polarization, a horizontal grid is arranged on a sub-reflector whose arbitrary cross section including the rotational symmetry axis is a hyperbola or ellipse, and a main reflector whose arbitrary cross section including the rotational symmetry axis is a parabola Since the configuration is such that the grid is arranged at an angle of 45 ° on the upper side, the configuration of the primary radiator is simplified, and there is an effect that high efficiency and low side lobe characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a front view of a main reflecting mirror according to the present invention.

FIG. 3 is a sectional view of a main reflecting mirror according to the present invention.

FIG. 4 is a sectional view showing a conventional dual-frequency antenna.

FIG. 5 is a diagram showing a primary radiator of a conventional dual frequency shared antenna.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 primary radiator 2 sub-reflector 3 main reflector 4 axis of rotational symmetry 5 aperture 6 45 ° grid 7 horizontal grid 8 conductor plate 9 incident radio wave 10 component orthogonal to grid of incident radio wave 11 component parallel to grid of incident radio wave 12 Component orthogonal to the grid of reflected radio waves 13 Component parallel to the grid of reflected radio waves 14 Reflected radio waves

Claims (2)

(57) [Claims] 1. A main reflecting mirror whose arbitrary section including a rotationally symmetric axis is a parabola, and a secondary reflecting mirror whose arbitrary section including a rotationally symmetric axis is coincident with the focal point of the parabola by one focal point. And a primary radiator placed at the focal point of the main reflector, and a primary radiator placed at a focal point other than that of the sub-reflector, wherein the primary radiator is placed at the focal point of the main reflector. The primary radiator is excited by vertical polarization, the other primary radiator is excited by horizontal polarization, a 45-degree grid is arranged on the main reflector, and a horizontal grid is arranged on the sub-mirror. A dual frequency antenna device according to claim 1. 2. A main reflecting mirror whose arbitrary cross section including the axis of rotational symmetry is a parabola, and a secondary reflecting mirror whose arbitrary cross section including the axis of rotational symmetry coincides with the focal point of the parabola and one focal point. And a primary radiator placed at the focal point of the main reflector, and a primary radiator placed at a focal point other than that of the sub-reflector, wherein the primary radiator is placed at the focal point of the main reflector. The primary radiator was excited with horizontal polarization, the other primary radiator was excited with vertical polarization, a 45-degree grid was arranged on the main reflector, and a vertical grid was formed on the sub-reflector. A dual-frequency antenna device, wherein the antenna device is arranged.