JPH02271702A - horn antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horn antenna used for a microwave band parabolic antenna or the like.

[Prior Art] Horn antennas are widely used as primary radiators such as microwave band parabolic antennas.

The conical horn antenna is excited by a TE+t mode wave, which is the fundamental mode of a circular waveguide. In this case, the beam width of the E-plane is narrower than the beam width of the H-plane and higher than the sidelobes of the E-plane. Further, the level of cross-polarization within the 45'' plane is also high, and in the case of circularly polarized waves, the elliptical polarization rate increases when the waves deviate from the front direction.

To overcome these disadvantages, multimode horn antennas and hybrid mode horn antennas such as corrugated horn antennas have been used.

[Problems to be Solved by the Invention] However, the conventional multi-mode horn antenna has a problem in that the fundamental mode of the circular waveguide, TE, mode waves, and one of the higher-order modes, TM, are transmitted through its aperture. This method synthesizes the waves so that they are in phase on the surface of the waveguide, such as those with a step-shaped discontinuous part in a circular waveguide, those with a dielectric sleeve loaded on the inner wall of the horn, those with multiple flares, and those with an iris. Many types of materials have been proposed, including those using flares, but all of them require time and effort to process and have problems such as lack of stability.

On the other hand, a corrugated horn antenna has thin comb-like fins on the inner wall of a circular waveguide to propagate EH mode waves, which is one of the hybrid modes, and the height of the teeth inside the corrugated waveguide is When the wavelength is approximately λ/4 (λ−wavelength), the axially symmetric beam and the cross-polarized wave characteristics are good, but the antenna structure becomes complicated and the cost becomes high.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a horn antenna with a sufficiently simple structure and high antenna characteristics.

[Means for Solving the Problems] EH, the aperture surface electrolytic distribution of the mode wave becomes a substantially Gaussian distribution in the radial direction, and has an axially symmetrical shape with no change in the circumferential direction. In other words, in a corrugated horn, E at the inner diameter
The distribution of , ,H, is symmetric. In a waveguide loaded with a dielectric film, the tangential components E, . . . E2 of electrolysis at the inner wall (r-b) of the waveguide are 0, but H, . . . Hl are present.

Figure 5 shows the characteristics of a normal horn antenna. In a normal horn antenna in the rr-bJ state without any special treatment applied to the inner wall of the waveguide, as shown in the figure, < rY/b-
1, OJ becomes rE, -OJ, which is not symmetrical with Hl. Therefore, in order to make the distribution of Ea and Ha symmetrical like in a corrugated horn, it is conceivable to raise E to the same level as Hl or to lower Ho to the same level as E.

FIG. 6 shows the concept of the electric field E generated on the waveguide wall. As shown in the figure, when Hl exists on the wall of the waveguide, a current density J is generated and flows in the circumferential direction. If the tube wall is a perfect conductor (R-0), rE, -OJ, but if a resistive film is formed on the tube wall, a potential difference will be generated there, and an electric field E.theta. will be induced in the circumferential direction.

Taking advantage of this point, the present invention forms a dielectric film on the inner wall of the antenna made of a conductor with a resistor film interposed therebetween, and induces an electric field E on the waveguide wall to generate the electric field E and H6. The distribution is made symmetrical.

[Operation] By doing as described above, it is possible to obtain a horn antenna having an axially symmetrical beam and good cross-polarization characteristics without using a complicated structure.

[Example code] The present invention will be described in detail below with reference to the drawings.

Figure 1 shows the structure of one embodiment, and Figure 1 (A
) is the axial cross section, and Figure 1 (B) is the I- in Figure 1 (A).
A cross section of the opening along line I is shown. In the figure, 11 is a conical horn antenna made of a conductor, 12 is a resistor film attached to the entire inner wall of the conical horn antenna 11, and 13 is a conical horn antenna 11 with the resistor film 12 interposed therebetween.
This is a dielectric film that is attached to the entire inner wall of the

With such a structure, the tangential component E of the electric field on the tube wall of the conical horn antenna 11.

EZ is 0, but H,, Hl come to exist.

When this Hl exists, a current flows in the opening of the conical horn antenna 11 in the circumferential direction. At this time, since the conical horn antenna 11 is provided with the resistor film 12 as described above, a potential difference is generated and an electric field E in the circumferential direction is induced. Therefore, by appropriately selecting the film thickness of the resistor film 12 and setting its resistance value, rEs *He J can be obtained.

As a result, the TE mode and TM mode in the waveguide have the same amplitude and are symmetrical, and by making the beam widths of the H-plane and H-plane the same, and adding a circular polarization generator, the cross-polarization characteristics can be significantly improved. can be improved.

Further, by changing the thickness of the dielectric film 13, the surface impedance can be changed and the magnitude of H2 can be controlled.

FIG. 2 shows the directivity characteristics of the above embodiment. The frequency is 12 GHz, the inner diameter of the aperture of the conical horn antenna 11 is 75 fflI111, the resistor film 12 is made of ferrite and has a thickness of 1 mm, the dielectric film 13 is made of polyethylene and has a film thickness of 3 a + m, the Z direction is the front, and the directivity angle is 0 @. .

Relative electric field strength? When fpJ is determined, the directivity of the 8th plane and the H plane become almost symmetrical, as shown in the figure.

This is ±50° compared to the case of only the conical horn antenna 11 without the resistor film 12 and dielectric film 13.
This means that an improvement of several dB was achieved within the range.

The following Figure 3 shows the structure of another embodiment.
Figure (A) shows the cross section in the axial direction, and Figure 3 (B) shows the same view (A).
A cross section of the opening along the line ■-■ is shown.

In the figure, 21 is a pyramidal horn antenna made of a conductor;
22 is a resistor film attached to a pair of opposing inner walls of the pyramidal horn antenna 21, and 23 is also attached to a pair of opposing inner walls of the pyramidal horn antenna 21 with the resistor film 22 interposed therebetween. It is a dielectric film.

With such a structure, the tangential component Ex of the electric field on the tube wall of the pyramidal horn antenna 21.

Ez is 0, but Hx and H2 come to exist.

When this H2 exists, a current flows in the opening of the pyramidal horn antenna 21 in the circumferential direction. At this time, since the pyramidal horn antenna 21 is provided with the resistor film 22 as described above, a potential difference is generated and an electric field E in the circumferential direction is induced. Therefore, by appropriately selecting the film thickness of the resistor film 22 and setting its resistance value, it is possible to obtain "Ex÷HxJ".

As a result, the TE mode and TM mode in the waveguide have the same amplitude and are symmetrical, and by making the beam widths of the 8-plane and H-plane the same, and adding a circular polarization generator, the cross-polarization characteristics can be significantly improved. can be improved.

Although the pyramidal horn antenna 21 is used here as the horn antenna, a fan-shaped horn antenna has exactly the same effect, so a description thereof will be omitted.

The following Fig. 4 also shows the structure of another embodiment, and Fig. 4(A) is a cross section in the axial direction, and Fig. 4(B) is a cross section taken along the line IV-IV in Fig. 4(A). A cross section of the opening is shown. In the figure,
31 is a conical horn antenna made of a conductor; 32 is a pair of resistor films mounted to face the inner wall of the conical horn antenna 31; and 33 is a conical horn antenna with the resistor film 32 interposed therebetween. These are a pair of dielectric films mounted so as to face each other on the inner walls of 31.

With such a structure, the tangential component Ex of the electric field on the tube wall of the conical horn antenna 31.

EX is 0, but HX and H2 come to exist.

When this H2 exists, a current flows in the opening of the conical horn antenna 31 in the circumferential direction. At this time, since the conical horn antenna 31 is provided with the resistor film 32 as described above, a potential difference is generated and a circumferential electric field Ex is induced. Therefore, by appropriately selecting the film thickness of the resistor film 32, setting its resistance value, and supplying power in TE++ mode, for example, rEx:HxJ can be obtained.

In addition, in the above embodiment and other embodiments, all explanations have been made using a horn antenna that radiates radio waves into space, but other antennas such as a corrugated horn antenna may be connected to this horn antenna to generate a symmetrical mode generator. It is also possible to use it as

[Effects of the Invention] As detailed above (according to the present invention, since a dielectric film is formed on the inner wall of the antenna made of a conductor with a resistor film interposed therebetween, the structure can be made sufficiently simple, and It has an axially symmetrical beam and good cross-polarization characteristics over a wide frequency band, and is used as a frequency reuse technology using two orthogonal polarizations, linear or circular polarization, used in satellite communications and satellite broadcasting. It is possible to provide a horn antenna that can achieve great effects.

[Brief explanation of drawings]

FIG. 1(A) is a sectional view showing the structure of an embodiment of the present invention;
Fig. 1 (B) is an aperture cross-sectional view taken along line I-I in Fig. 1 (A), Fig. 2 is a directivity characteristic diagram of the first horn antenna,
FIG. 3(A) is a sectional view showing the structure of another embodiment of the present invention, FIG. 3 CB) is an opening sectional view taken along the line ■-■ in FIG. 3(A), and FIG. 4(A) 4(B) is an opening sectional view taken along line IV-IV in FIG. 4(A), and FIGS. 5 and 6 are sectional views showing the structure of another embodiment of the present invention. It is a diagram for showing the concept. +1.31... Conical horn antenna, 12.22.
32...Resistor film, 13.23.33...Dielectric film, 21...Pyramidal horn antenna. L■ (A) Applicant's agent Takehiko Suzue Amplitude diagram Directivity angle (degrees) Figure 2 Figure 4

Claims (5)

[Claims] (1) A horn antenna characterized in that a dielectric film is formed on the inner wall of the antenna made of a conductor with a resistor film interposed therebetween. (2) The horn antenna according to claim 1, wherein the horn antenna is a conical horn antenna, and the dielectric film with the resistor film interposed therebetween is formed on the entire inner wall of the antenna. (3) The horn antenna is a pyramidal horn antenna, and the dielectric film with the resistor film interposed therebetween is formed on opposing surfaces of the inner wall of the antenna.
1) Horn antenna described. (4) Claim (1) wherein the horn antenna is a fan-shaped horn antenna, and the dielectric film with the resistor film interposed therebetween is formed on opposing surfaces of an inner wall of the antenna.
) described horn antenna. (5) The horn antenna according to claim 1, wherein the horn antenna is a conical horn antenna, and the dielectric film with the resistor film interposed therebetween is formed on a part of the inner wall of the antenna.