JPS6029209Y2 - antenna power supply device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a power feeding device comprising a horn antenna and a plane reflecting mirror placed at a predetermined inclination in close proximity to the front direction of the horn antenna.

First, a conventional power supply device will be explained based on FIG.

In Figure 1, 1 is a horn antenna, 2 is its input end, 3 is a plane reflector, 4 and 4' are incident waves entering the plane reflection mirror from the horn antenna, and 5 and 5' are plane reflections. This is a reflected wave from a mirror.

Further, θi and θr are the incident angle and the reflection angle, respectively, and are the angles formed by the normal line on the plane reflecting mirror 3 and the incident wave and the reflected wave.

The plane reflector 3 is placed close to the horn antenna 1 at a predetermined inclination, and the radio waves radiated by the horn antenna 1 are incident on the plane reflector 3 at an incident angle θi, and are reflected so as to satisfy the following equation. do.

θi=θr (1) Usually, the mirror system of a power supply device or an antenna device is designed using a geometrical optics method.

However, since radio waves have a wider electric field distribution than when considered in terms of geometrical optics, the paths of the incident wave 4' and reflected wave 5' in geometrical optics indicated by dotted lines in Figure 1 are actually solid lines. The incident wave 4 and the reflected wave 5 are represented by , and they propagate in a predetermined direction while satisfying the first equation.

Therefore, when the plane reflector 3 is in the vicinity of the horn antenna 1, a part of the reflected wave 5 reflected at the closest part of the plane reflector 3 and the horn antenna 1 leaks into the horn antenna 1, and This has the disadvantage that it degrades the VSWR characteristic of the feeder as viewed from the input end 2 of the horn antenna 1 shown in FIG.

Therefore, as a method to eliminate the above drawbacks, the conventional method was to
As shown in the figure, a method has been adopted in which a radio wave absorber 6 is attached around the plane reflector 3 to absorb radio waves around the plane reflector 3.

Here, FIG. 2A is a front view of the power supply device, and FIG. 2A is a side view.

However, there is a limit value to the amount of radio waves absorbed by the radio wave absorber 6, and radio waves that cannot be absorbed leak into the horn antenna 1, degrading the VSWR characteristic of the power feeding device as viewed from the input end 2 of the horn antenna 1.

Therefore, if an attempt is made to increase the amount of radio waves absorbed by the radio wave absorber 6, the thickness of the radio wave absorber 6 increases, resulting in the drawback that it absorbs a portion of the necessary radio waves.

This invention improves these drawbacks.More specifically, in place of the radio wave absorber 6, a dielectric ring is attached around the plane reflector 3, so that the plane reflector 3
This is intended to prevent a part of the reflected wave 5 from entering the horn antenna 1 and deteriorating the VSWR characteristic as seen from the input end 2 of the horn antenna 1.

An embodiment of this invention will be described below with reference to FIG.

1.2.3 in Figure 3 a and b and 4.5 in Figure 3 are the first
It is the same as that shown in Fig. 2, and 7 is a plane reflecting mirror 3.
It is a dielectric ring attached around the .

The outer shape of the plane reflecting mirror 3 is an ellipse, and the dielectric ring 7 is also shaped along that shape.

FIG. 4 shows the shape of the dielectric ring 7.

FIG. 4a is a plan view of the dielectric ring 7, and FIG. 4 is a side view of the dielectric ring 7.

w and d shown in FIGS. 4a and 4b are the width and thickness of the dielectric ring 7.

The width W of the dielectric ring 7 is determined by the electric field strength around the plane reflector 3 and varies depending on the type and shape of the horn antenna 1 and the arrangement of the plane reflector 3.

The thickness d of the earth dielectric ring 7 is determined to satisfy the following equation.

d≧〜胛02碩可-1) “””(2) That is, the second
The formula is derived from the condition that the reflected waves 5 and 5'' are in opposite phases using the property of shortening the wavelength of radio waves in a dielectric body, as explained with reference to FIG.

No, in the second equation, input 7 is the free space wavelength of the center frequency in the frequency band used, and E is the relative dielectric constant of the dielectric.

In addition, α is the angle between the central axis of the horn antenna 1 and the plane reflector 3, which is the angle measured counterclockwise from the central axis of the horn antenna 1, and β is the angle between the central axis of the horn antenna 1 and the axis perpendicular to the central axis. This is the angle between the incident wave 4 that enters the plane reflector 3 from the horn antenna 1, and is the angle measured counterclockwise from the orthogonal axis.

Here, α and β are 0°<β<180°, lβ−α1<
This value satisfies 900.

To further explain the details with reference to FIG. 5, the symbols 1°2.3,
4, 5, and 7 are the same as those shown in FIG. This is a reflected wave.

In FIG. 5, the wavelength of the radio waves in the dielectric ring 7 is 1/It compared to the free space wavelength, so the dielectric ring 7 with a thickness d that satisfies the second equation is placed around the plane reflecting mirror 3. By attaching the dielectric ring 7 to the horn antenna 1, the phase of the reflected wave 5'' directed from the dielectric ring 7 to the horn antenna 1 is opposite to that of the reflected wave 5 directed from the plane reflector 3 to the horn antenna 1, so that they cancel each other out. Become.

Therefore, leakage of reflected waves 5 from the periphery of the plane reflector with a dielectric ring into the horn antenna 1 can be eliminated, and deterioration of the VSWR characteristics of the power feeding device viewed from the input end of the horn antenna 1 can be prevented. .

As described above, V of the power supply device having a flat reflector with a dielectric ring
Although the principle of preventing SWR deterioration has been described, the shape of the dielectric ring 7 can be a rectangular cross section 8 as shown in FIG. The dielectric ring 7 may have a cross section 9 of a semicircular or similar shape.

Furthermore, as shown in FIG. 6C and d, a part of the dielectric ring 7 is attached around the plane reflector 3, which is most effective for preventing the reflected waves 5 from leaking into the horn antenna 1. You can also do that.

Furthermore, in the second equation, 1. of the dielectric ring 7. If the value becomes large, the amount of reflection from the surface of the dielectric ring 7 will inevitably increase, and the effect of the dielectric ring 7 will decrease.

In order to suppress this reflection, a portion of a cut dielectric ring 7 having a predetermined width in the radial direction may be installed in an array along the periphery of the plane reflector, as shown in FIG. .

Here, reference numerals 1 and 2 in FIG. 3 is similar to that shown in FIG.

In particular, the dielectric ring 7 shown in FIG. 6d is manufactured so that the radius of the semicircle in its cross-sectional shape satisfies the second equation.

In this case, the leakage of reflected waves 5 from the periphery of the dielectric ring-attached plane reflecting mirror into the horn antenna cannot be completely eliminated compared to the dielectric ring 7 having a rectangular cross section.

However, the dielectric ring 7 with a semicircular cross section does not have corner parts unlike the dielectric ring 7 with a rectangular cross section, so the advantage is that scattered waves are not generated from these parts, and therefore the radiation pattern does not deteriorate. have.

Furthermore, in the second equation, it was stated that input 8 is the free space wavelength of the center frequency in the used frequency band. It can also be a free space wavelength with a significant frequency of .

Although the case of a single power feeding device has been described above, the present invention can also be applied to an offset Cassegrain antenna as shown in FIG. 8 as an application example.

In FIG. 8, 10 is a rotating quadratic curved mirror to a sub-reflector;
11 is a main reflecting mirror made of a parabolic mirror of revolution.

As described above, according to this invention, by attaching the dielectric ring 7 around the plane reflector 3 which is placed at an arbitrary inclination close to the front direction of the horn antenna 1, the reflection from the plane reflector 3 is reduced. The waves 5 can be prevented from entering the horn antenna, and the VSWR characteristics of the power feeding device viewed from the input end 2 of the horn antenna 1 can be improved.

Furthermore, the dielectric ring 7 has the advantage that it can be made thinner by increasing its dielectric constant.

[Brief explanation of the drawing]

FIGS. 1 and 2 at b are block diagrams showing a conventional power feeding device, and FIGS. 3 a and b are block diagrams showing a power feeding device of this invention.
Figure 4 a and b are explanatory diagrams of the dielectric ring, and Figure 5 is the third
Detailed views of Figures 6a, b, c. b1 Figure 7 is a diagram showing various dielectric rings, and Figure 8 is a configuration diagram of an offset Cassegrain antenna showing an application example of this invention. In the figure, 1 is a horn antenna, 2 is a feeding end of the horn antenna, and 3 is a plane reflecting mirror, 4, 4' are incident waves on the plane reflecting mirror,
4" is the incident wave on the dielectric ring, 5.5' is the reflected wave from the plane reflecting mirror, 5" is the reflected wave from the dielectric ring, 6 is the radio wave absorber, 7 is the dielectric ring, and 10 is rotation. A sub-reflector 11 is a quadratic curved mirror, and a main reflector 11 is a paraboloid of revolution. Note that the same reference numerals are used in the figures or corresponding parts.

Claims (5)

[Scope of utility model registration request] (1) Near the horn antenna and its front direction,
In an antenna feeder that also has a flat reflector placed at a predetermined inclination, α is the angle between the central axis of the horn antenna and the flat reflector, and β is the angle between the central axis of the horn antenna and the angle perpendicular to the central axis of the horn antenna. The angle between the incident wave and the incident wave entering the plane reflecting mirror is λ9. ξ is the free space wavelength of the center frequency and the permittivity of the dielectric material, respectively, and the thickness d satisfies the following: d = Hakusen Egg Nikun Temite - 1) A dielectric ring is attached around the above flat reflector. Mirror power supply device. (2) Utility Model Registration Scope of the Claims The antenna power supply device according to claim 1, in which a dielectric ring having a rectangular cross section is attached around a flat reflecting mirror. (3) Utility Model Registration Scope of the Claims The antenna power supply device according to claim 1, in which a dielectric ring having a cross-sectional shape of a semicircle or a similar shape is attached around a flat reflecting mirror. (4) Scope of Utility Model Registration In the antenna feeding device according to any one of claims 1.2.3, a part of the dielectric ring cut into an arbitrary circular arc is placed around the plane reflecting mirror. Attached antenna power supply device. (5) Utility model registration In the antenna feeding device according to any one of claims 1 to 4, the antenna feeding device includes a plurality of dielectric rings or parts thereof arranged in an array along the periphery of a flat reflector. Device.