JPS61135201A - Porous high-degree mode coupler - Google Patents

Abstract

PURPOSE:To eliminate the adverse effects of an undesired high-degree mode of transmission to an antenna radiation pattern, by setting a resistance plate to a face vertical to the field vector of a basic mode within a rectangular secondary waveguide. CONSTITUTION:The transmission radio wave S passing through a primary waveguide 2 is partly leaked out with connection of a magnetic field secured to a secondary waveguide 1 through a coupling hole 3. Then the TM wave is transmitted within the waveguide 1. This TM wave is leaked out again to the waveguide 2 via the hole 3 as shown by an arrow 8 in case no resistance plate 4 is provided. While the TM wave passing within the waveguide 1 is absorbed by the plate 4 if provided and is not leaked out to the waveguide 2. This can avoid the adverse effects of an undesired high-degree mode to an antenna radiation pattern.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a porous high-order mode coupler used for detecting information for tracking a satellite by an antenna of an earth station in microwave satellite communication. This invention relates to improving the suppression of unnecessary higher-order modes during transmission.

(Prior art) A porous higher-order mode coupler is composed of a main waveguide and a sub-waveguide, and the image forming part is electromagnetically coupled through a plurality of coupling holes formed on the side surface of the main waveguide. A specific higher-order mode passing through the main waveguide is coupled to the sub-waveguide.

In satellite communications, when the earth station antenna is deviated from the direction of the satellite, the earth station antenna automatically tracks the satellite by detecting a specific high-order mode that occurs in the circular waveguide of the antenna feeder. It is used as a control signal.

The porous high-order mode coupler is used to extract a specific high-order mode electromagnetic wave generated within the circular waveguide of the antenna feeding section.

In other words, when the direction of the earth station's antenna deviates from the satellite, the higher-order mode electromagnetic waves generated in the circular waveguide of the antenna feed section by the waves received from the satellite are transferred to the sub-waveguide of the porous higher-order mode coupler. The antenna is connected to a tube and taken out to obtain the signals necessary for automatic tracking of the antenna, which controls the direction of the antenna so that it always faces the satellite.

For this reason, in satellite communications, the size, shape, and spacing of the coupling port of a porous high-order mode coupler are determined so that the degree of coupling is optimal for the high-order mode of the received wave.

However, when the transmitted wave also passes through this higher-order mode coupler, a part of it leaks to the sub-waveguide. The conventional method for spinning this is to provide a metal blocking rod in the coupling hole to suppress leakage of transmitted waves to the sub-waveguide.

(Problem to be solved by the invention) Currently, in satellite communications, as the demand for information increases, the frequency bands used are being expanded, and this expansion is being done in both directions, towards higher and lower frequencies. It is. For example, C-band (4/6 GH
In the Z band), the band is extended to lower frequencies, and in that case, it is necessary to increase the diameter of the circular main wave tube of the conventional porous higher-order mode coupler. However, the amount of electromagnetic field coupling due to one coupling hole of the same shape is inversely proportional to the square of the radius of the circular waveguide, so in order to obtain the same amount of coupling as before when the diameter is increased, more coupling holes are required. In addition, the distance between the coupling holes must be shortened.

In this way, when a transmitted wave is passed through the main waveguide of a porous high-order coupler with a large number of coupling holes and narrow spacing between the coupling holes, the coupling holes are Due to the narrow spacing between the coupling holes, a small amount of the transmitted waves leaking to the sub-waveguide due to magnetic field coupling are emphasized.
Excite TM waves in the sub waveguide.

However, this TM wave excited within the sub-waveguide propagates within the sub-waveguide and leaks back into the main waveguide via the coupling hole, generating a higher-order mode electromagnetic field within the main waveguide. This has a major problem in that it adversely affects the radiation pattern of the antenna.

(Means for Solving the Problems) In view of the problems of the conventional porous high-order mode coupler, the present invention aims to solve the problem of high-order mode electromagnetic waves (TE waves) due to received waves from satellites. coupling to the sub-waveguide and propagation within the sub-waveguide, while preventing the TM wave caused by the transmitted wave leaking into the sub-waveguide from leaking back toward the main waveguide. By providing this means, it is intended to eliminate the negative influence on the radiation pattern of the antenna.

The present invention has the following configuration to achieve the above object.

That is, in the porous higher-order mode coupler, the fundamental mode (T
This is a porous higher-order mode coupler in which a resistive plate attenuator is installed along a plane perpendicular to the electric field vector of E1 mode).

(Function) A resistive plate placed in a field does not absorb an electric field perpendicular to it, but absorbs an electric field parallel to the resistive plate.

Now that the direction of the earth station antenna has shifted from the direction of the satellite, the high-order mode electromagnetic waves generated in the antenna feed 'wL part by radio waves received from the satellite are inside the sub-waveguide of the porous high-order wire coupler. The mode in is TE mode and 6D, whereas the electromagnetic wave excited in the sub-waveguide by the transmitted wave is TM mode.In the present invention, as described in the above means, the TI mode electric field vector in the sub-waveguide is A resistance plate is provided along the vertical plane. Therefore T.E.
No absorption effect occurs for the electromagnetic field of the mode. However, since the electric field vector in the TM mode also includes an electric field component having a direction parallel to the surface of the resistor plate, this electric field energy is absorbed by the resistor plate. Thus, in the sub-waveguide of the porous higher-order mode coupler, the higher-order TE mode waves due to the waves received from the satellite are not affected at all, and only the TM mode electromagnetic waves due to the transmitted waves are absorbed by the resistive plate and weakened. Therefore, the strength of the electromagnetic field that leaks back from the sub-waveguide to the main waveguide via the coupling hole is also weakened, and its adverse effect on the radiation pattern of the antenna is also reduced.

(Example) FIG. 1 shows a TE mode coupler as an example of a porous higher-order mode coupler. The porous higher-order mode coupler consists of a main waveguide 2 and a sub-waveguide 1, which are electromagnetically coupled through a plurality of coupling holes 3.

4 is a resistance plate.

FIG. 2 is a detailed view of the coupling part, sub-waveguide, and resistance plate installation. FIG. 3 is a diagram showing an example of the shape of the resistance plate. Second
In the figure, the X-axis is TE in a rectangular sub-waveguide. It shows the direction of the electric field of the mode, and the Z axis shows the direction of travel of the electromagnetic wave. The resistance plate 4 is a thin one (for example, a mica plate with carbon deposited on it) with both ends tapered as shown in Fig. 3 to reduce the standing wave ratio. ,, plane perpendicular to the electric field direction of the mode (Fig. 2 y - z
is mounted parallel to the plane).

FIG. 4 shows the transmission mode within the rectangular sub-waveguide. Figure (al is a figure showing TE, 0 mode, figure (b) is a figure showing TM, l mode. In both figures, 5 indicates the direction of the electric field vector, and 6 indicates the direction of the magnetic field. .Now, since the resistor plate is provided parallel to the y-z plane, TEl in the figure (IL).

It is perpendicular to the electric field vector 5 of the mode.

In other words, in this case, the electromagnetic wave is not absorbed by the resistance plate (b
), the electric field vector 5 is radial and therefore includes a component parallel to the yz plane. Therefore, the parallel component will be absorbed by the resistance plate.

FIG. 5 schematically shows the leakage of radio waves from the main waveguide to the sub waveguide in the TEo mode coupler. S represents the transmitted wave, and R represents the higher-order mode due to the received wave [4! I
represents waves. A part of the transmitted radio wave S passing through the main waveguide 2 undergoes eight-field coupling from the coupling hole 3 to the sub-waveguide 1, leaks, and propagates in the sub-waveguide 1 as a TM wave. If there is no resistance plate, T
The M wave passes through the coupling hole 3 again to the main waveguide 2 as shown by arrow 8.
leak to. However, by providing a resistor plate 4 as shown in the figure, the TM wave propagating inside the sub-waveguide 1 can be controlled by the resistor plate 4.
The re-leakage to the main waveguide 2 as shown by the arrow 8 is almost eliminated, and the adverse effects on the antenna radiation pattern etc. are suppressed.

On the other hand, the higher-order mode electromagnetic wave R due to the received wave passes through the coupling hole 3 and passes through the rectangular sub-waveguide 1 TE. In this case, the electric field vector 5 is perpendicular to the surface of the resistor plate 40, so it passes through the sub-waveguide without being affected.

The present invention is not limited to the T E at odd mode combiner, but also a porous higher-order mode combiner (
For example, in a TE*t mode coupler, T Mat mode coupler, etc., the sub waveguide is a rectangular waveguide, and the necessary signal is passed through the rectangular waveguide. mode, and the unnecessary mode is TM,
This is effective when propagating in one mode.

(Effects of the Invention) As explained above, the porous high-order mode coupler of the present invention includes a TE in the rectangular sub-waveguide. By providing a resistor plate on a plane perpendicular to the electric field vector of the mode, even if the number of coupling holes is large and the spacing between them is narrow, the TE of higher-order modes caused by received waves can be suppressed.
By lowering the frequency band used, it is possible to suppress unnecessary higher-order modes caused by TM waves leaking from the transmitted wave through the sub-waveguide without affecting wave extraction. Even when the diameter of the waveguide becomes larger and the number of coupling holes increases accordingly, and the spacing between the coupling holes becomes narrower, there is an advantage that it is possible to eliminate the adverse influence on the antenna radiation pattern due to higher-order modes that do not require transmission.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the structure of a porous higher-order mode coupler (T E @ l mode), and Figure 2 is a diagram showing the coupling part of the mode coupler and the state in which the resistor plate is attached to the sub-waveguide. 3 is a diagram showing the shape of the resistance plate, FIG. 4 is a diagram showing the transmission mode in the rectangular sub-waveguide, and FIG. 5 is TE,
FIG. 3 is a schematic diagram of transmitted wave leakage of a mode coupler.

Claims (1)

[Claims] 1) In a porous higher-order mode coupler, the fundamental mode (T
A porous higher-order mode coupler characterized by having a resistive plate attenuator installed along a plane perpendicular to the electric field vector of the E_1_0 mode).