JPS6126304A - Horn antenna - Google Patents

Abstract

PURPOSE:To avoid deterioration of an antenna radiation pattern by providing a cover fitting frame using a dielectric as a raw material near the horn outer surrounding and fitting a horn cover to an aperture end face of a cover fitting frame at a prescribed interval from the horn aperture face and tilted to the face at a right angle to the horn center axis. CONSTITUTION:The cover fitting frame 5 is provided to the horn antenna comprising a square horn 1 and a square waveguide 2. The frame 5 has a horn cover fitting end face and a fixed end face fixing the cover fitting frame, the cross section is square and the frame is made of a dielectric. The cover fitting face has a distance of 1/4 of wavelength of the operating radio wave from the horn aperture face and is cut obliquely so as to support the horn cover with an angle. The horn cover 3' is bonded to the aperture end face and the outer peripheral part of the frame 5. Since the cover fitting flange provided to the horn aperture is removed, the deterioration of the radiation pattern due to a current leaked to the flange is not almost observed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a horn cover provided at the horn opening of a horn antenna (or -order radiator) used, for example, in the microwave band or sub-millimeter wave band. This concerns the shape and mounting structure.

Generally, a horn cover is fixed to cover the horn opening, and is widely used for the purpose of preventing dust, rain, and snow from entering. Further, the horn cover is fixed in an airtight manner, and plays a role as a fog prevention window that constantly feeds dry air into the horn and power supply line to prevent dew condensation inside.

(Prior Art) Figure 4 shows an example of a conventional horn cover mounting structure. Figure (a) is a front view, figure (b) is a left side view, and the broken line in the figure indicates the internal structure. show. This example shows a square horn,
This figure shows a single horn composed of a square waveguide and a horn cover, and in the figure, numeral 2 is a square horn, 2 is a square waveguide, 3 is a horn cover, and 4 is a small diameter bolt.

Seven square waveguides 2 are connected to a square horn 1 so as to share the central axis of the horn. The horn cover 3 is fixed with an adhesive to a cover attachment 7 flange provided in a shape that frames the horn opening, and is bolted with small diameter bolts 4.

(Problems to be Solved by the Invention) In the conventional horn cover mounting structure as described above, a cover mounting 7-lunge must be provided at the horn opening.
The size of the 7-lunge needs to be wide enough to tighten a small diameter bolt, and when used in a quasi-millimeter wave band or a millimeter wave band, it will be relatively large compared to the horn opening size. This causes a phenomenon in which current leaks and flows through the cover mounting flange, and the electromagnetic field distribution at the horn aperture is greatly disturbed compared to the case without the seven lunges, resulting in deterioration of the antenna radiation pattern. Ideally, it is desirable not to provide seven lunges in the horn opening, but also to make the thickness of the side wall of the horn opening as thin as possible.

On the other hand, for the horn cover, the material selection and thickness are mainly determined by considering the frequency of use, but the mechanical strength conditions of the cover must also be considered, which adds restrictions to the selection and decision making. , deterioration of electrical characteristics, especially input voltage standing wave ratio (Voltage Standing Wave Ratio)
e Ratio: V SWR) deterioration is unavoidable.

As described above, the conventional method has major drawbacks in that it adversely affects the antenna radiation pattern and degrades the input VSWR.

(Means for Solving the Problems) An object of the present invention is to provide a horn antenna that eliminates these drawbacks of deterioration of electrical characteristics and has sufficient mechanical strength for practical use.

The present invention goes back to the basics of not providing a 7-lunge in the horn opening, and instead of the 7-lunge, a cover mounting frame made of a dielectric material is newly provided near the outer circumference of the horn, and the cover mounting frame is At a predetermined distance from the horn opening surface to the opening end surface of the
Further, the present invention is characterized in that a horn cover is attached which has a flat or curved surface or a combination thereof that is inclined with respect to a surface perpendicular to the central axis of the horn.

That is, the horn antenna of the present invention includes a horn cover having a shape having a flat surface or a curved surface that is inclined with respect to a plane perpendicular to the central axis of the horn, or a composite surface of the sloped surface and the curved surface.
This horn antenna is characterized in that it is installed at a distance of approximately one-fourth of the wavelength of the radio wave used from the horn opening surface by means of a horn cover mounting frame made of a dielectric material fixed near the horn's outer circumference.

(Function) The horn antenna of the present invention has the above-described structure, so there is no need to attach a horn cover directly to the horn opening surface, so there is no need to provide a flange at the horn opening. The leakage current at the side wall end face of the horn opening can be made as thin as possible, and the leakage current causes less disturbance of the electromagnetic field distribution on the horn opening face, resulting in less deterioration of the antenna pattern.

Next, since the horn cover is located at a distance of approximately one-fourth of the wavelength of the radio waves used from the horn opening, the power reflected at the horn opening and the power reflected from the inner surface of the horn cover cancel each other out. This improves the human power VSWR characteristics.

Furthermore, since the surface of the horn cover is inclined from a surface perpendicular to the central axis of the horn, the electric power reflected from the inner surface of the horn cover toward the horn is reduced, which reduces human power V.
SWR41ii+ property is further improved.

(Example) The present invention will be described in detail below based on the drawings.

FIG. 1 shows a horn antenna showing an embodiment of the present invention; FIG. 1(a) is a front view, FIG. 1(b) is a left side view, and FIG. 1(c) is an external view. shows.

In the figure, numerals 1 and 2 are the same as in FIG. 4, 3' is a horn cover, 4 is a small diameter bolt, and 5 is a cover mounting frame for supporting and fixing the horn cover.

Components 1 and 2 are assembled and connected in exactly the same manner as shown in FIG. The cover mounting frame 5 has a horn cover mounting end face and a fixed end face for fixing the cover mounting frame, has a square cross-sectional shape, and is made of a dielectric material. The cover mounting surface is cut diagonally to allow a distance from the horn opening and to support and fix the horn cover at an angle.

The horn cover 3' is adhered to the open end surface and the outer periphery of the cover mounting frame 5, and is bolted near the fixed end surface of the outer periphery' as necessary.

According to the invention, the cover attachment 7 provided at the horn opening
By removing the lunge, the phenomenon of deterioration of the radiation pattern due to the current leaking through the 7-lunge part will hardly be observed. The use of a dielectric cover mounting frame is a major reason why the pattern is not adversely affected. on the other hand,
It can also be expected to be effective against deterioration of input VSWR caused by installing the horn cover. In other words, by installing the horn cover with a distance from the horn opening and tilting it with respect to a plane perpendicular to the horn center axis, it is possible to suppress as much as possible the characteristic deterioration of the input VSWR that could not be avoided with conventional ones. I can do it.

In other words, a remarkable effect can be achieved by selecting the cover mounting position at a distance approximately one-fourth of the operating wavelength so as to provide a condition where the power reflected at the horn opening and the power reflected from the surface of the horn cover cancel each other out. Ru. Of course, in the present invention, the material and sheet thickness of the horn cover must be determined in consideration of the operating frequency.

FIG. 2 is an external view showing a second embodiment of the invention. In this figure, the shape of the cover mounting end face of the cover mounting frame 5 is changed so that the horn cover is mounted in a roof shape.

FIG. 3 is an external view showing a third embodiment of the present invention. This is an example in which the horn cover is attached in a semicylindrical shape in exactly the same way.

There are various other shapes for installing the horn cover in addition to the above, but the selection of the shape should be determined experimentally by taking into account the material used for the horn cover, the sheet thickness, the frequency used, and the polarization used. It turns out. In either case, the same effects as described above can be obtained.

In the above explanation, the cross-sectional shape of the cover mounting frame is square. However, the cross-sectional shape is not limited to this, and any shape such as a triangle, rectangle, polygon, circle, or oval may be used as well. The effect of this can be obtained. Regarding the installation of the cover mounting frame, we have explained an example in which it is fixed to the 7 lunges of the waveguide, but it is possible to use any part to fix it. The essence of this invention is that it can be attached and installed. Further, although the explanation has been given using an example of a single horn consisting of one horn, the invention is not limited to this, and the application can also be applied to a multi-horn consisting of multiple horns such as two or three horns, and the same effect as described above can be obtained. It will be done. Furthermore, although the horn and the feed line have been described with an example having a square cross section, the present invention is not limited to this, and the same effect can be obtained by using, for example, a circular or rectangular cross section.

(Effects of the Invention) As explained above, the horn antenna (or -order radiator) according to the present invention is characterized by the mounting structure of the horn cover attached to the hole opening,
It has the following effects. That is, in the past, deterioration of the antenna radiation pattern was unavoidable due to the influence of the horn cover mounting flange provided at the horn opening, but with the horn antenna of the present invention, there is no need to provide seven lunges at the horn opening. Deterioration of the antenna radiation pattern can be removed. In addition, the horn cover is placed at a position one-fourth of a wavelength away from the horn opening surface, and has a multi-curved surface that is tilted to minimize the surface facing the horn opening surface, so that it does not fit inside the horn. There is an advantage that less power is reflected back, and as a result, input VSWRe characteristics are greatly improved.

In the /J% aperture horn antenna used in the quasi-millimeter wave band and the millimeter wave band, the ratio of the 7-lunge portion to the horn aperture area is large, so the effect of applying the present invention is large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a first embodiment of the horn antenna according to the present invention, FIG. 2 is a diagram showing the structure of the second embodiment of the horn antenna according to the present invention, and FIG. FIG. 4 shows the structure of a conventional horn antenna. 1... Hoy, 2... Waveguide, 3, 3'...
Horn cover, 4...Small diameter bolt, 5...Cover mounting frame Agent Patent attorney Yoshihiro Yahata Page 7

Claims (1)

[Claims] A horn made of a dielectric material and having a horn cover having a shape having a flat or curved surface that is inclined with respect to a plane perpendicular to the central axis of the horn, or a composite surface of the inclined surface and the curved surface, fixed near the outer circumference of the horn. A horn antenna characterized in that it is provided at a distance of approximately one-fourth of the wavelength of the radio wave used from the horn opening surface by means of a cover mounting frame.