JP2018170677A - Antenna feed circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antenna feeding circuit realizing downsizing compared with the conventional device while having sufficient cutoff performance of a high frequency signal.SOLUTION: The antenna feed circuit includes: a waveguide for passing a high frequency signal; and a waveguide composed of a 4-branch circuit for separating and synthesizing a signal of a low frequency. Each of branch waveguides connected to the 4-branch circuit has a structure in which a waveguide extending in a direction perpendicular to a tube axis direction of the 4-branch circuit is bent in parallel to the tube axis direction of the 4-branch circuit. A low-pass filter portion having a low-pass function is loaded near a connection portion with the 4-branch circuit. Further, a filter is loaded beyond a position where the waveguide is bent.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an antenna feeding circuit used for a satellite-mounted antenna or the like.

  In a multi-beam antenna using a reflecting mirror, a horn antenna that is a primary radiator of the reflecting mirror is disposed at a position corresponding to the beam direction. For example, in order to realize a two-dimensional densely arranged beam arrangement, it is necessary to arrange horn antennas densely. Therefore, the power feeding circuit connected to the horn antenna needs to be configured compactly.

  These horn antennas and power feeding circuits are arranged in high density without gaps. Therefore, mechanical interference between adjacent feeding circuits is a restriction on high-density arrangement.

  In particular, an OMJ (Ortho Mode Junction) circuit used for a feeding circuit of a reflector antenna for a multi-beam antenna is configured with a port that allows a high-frequency signal to pass through and a four-branch circuit that demultiplexes and combines a low-frequency signal. Is done. Here, in a satellite-mounted antenna, a high frequency signal typically corresponds to a reception signal, and a low frequency signal typically corresponds to a transmission signal. In this description, typical frequency and transmission / reception assignments are used, but this assignment may be reversed.

  The input / output terminals of the OMJ include a common terminal for receiving low and high band signals via a horn antenna, a high band terminal for outputting high band signals, and a low band via a branching waveguide. There are four low band terminals that output band signals.

  A low-frequency band signal is input from a low-frequency band terminal, each signal passes through a low-pass filter, is synthesized as a circularly polarized wave at the OMJ, and is output to a horn antenna via a common terminal. Note that the low-band signal is transmitted via the branch waveguide, but is reflected in the direction of the high-band terminal because it is cut off from the dimensions of the high-band waveguide, and the direction of the common terminal Is transmitted.

  The high-band signal input from the common terminal is transmitted to the common waveguide and the high-band waveguide, and the OMJ 4-branch circuit is loaded with a low-pass filter that cuts off the high-band signal. Since the high-band signal cannot pass through the low-pass filter, it is not transmitted to the outer branching waveguide.

  The low-pass filter loaded on the OMJ employs a stub filter type installed in a waveguide extending in a direction perpendicular to the high-band waveguide axis. The shape having the stub structure on both sides of the waveguide has the characteristics of a low-pass filter, and the shape having the stub structure on one side has the characteristics of a band rejection filter.

  Note that a filter must be disposed near the four-branch circuit connection in the branching waveguide in order to suppress characteristic deterioration due to the high-band signal entering the branching waveguide. Further, in order to sufficiently block the high-frequency signal, it is necessary to increase the number of stub stages, and the filter becomes long and the diameter of the power feeding circuit is increased.

  Patent Document 1 discloses that an OMJ is used as a polarization separation circuit and a low-pass filter is loaded on the OMJ.

Japanese Patent Laid-Open No. 2006-134039

However, the prior art has the following problems.
As described above, in order to sufficiently block the high frequency signal, it is necessary to increase the number of stub stages. This has been a cause of an increase in the diameter of the entire power feeding circuit. In particular, the power feeding circuit in the multi-beam antenna needs to be closely arranged by reducing the diameter of the power feeding circuit, and thus downsizing is essential.

  Although the above-mentioned patent document 1 discloses a method of using an OMJ as a polarization separation circuit and loading a low-pass filter on the OMJ, the circuit shape for miniaturizing the antenna feeder is disclosed. There is no suggestion.

  The present invention has been made to solve the above-described problems, and provides an antenna feeding circuit that has a sufficient high-frequency signal blocking performance and is smaller than conventional devices. Objective.

  An antenna feeding circuit according to the present invention includes an antenna feeding circuit configured to include a waveguide that allows a high-frequency signal to pass through and a waveguide that includes a four-branch circuit that demultiplexes and synthesizes a low-frequency signal. Each of the branch waveguides connected to the four-branch circuit has a waveguide extending in a direction perpendicular to the tube axis direction of the four-branch circuit in the tube axis direction of the high-band waveguide axis. A low-pass filter unit having a low-pass function is loaded near the connection with the four-branch circuit, and the filter is loaded at the end of the waveguide. It is what.

  According to the present invention, the effect of miniaturization is obtained by bending the branching waveguide in parallel with the high band waveguide axis. In addition, a low-pass filter unit having a low-pass function connected in a vertical direction with respect to the high-pass waveguide of the power feeding circuit, and a filter is further connected to the bent end of the waveguide. Yes. As a result, the number of stub stages in the low-pass filter is reduced, but the antenna feed circuit that realizes a smaller size than the conventional device while having sufficient high-frequency signal blocking performance by combining the filter characteristics of the latter stage. Can be obtained.

1 is a perspective view showing a configuration of a polarization separation circuit according to a first embodiment of the present invention. It is the perspective view which showed the rectangular branch waveguide by Embodiment 1 of this invention. It is operation | movement explanatory drawing of the antenna electric power feeding circuit in Embodiment 1 of this invention. It is the figure which showed the filter characteristic of the rectangular branch waveguide in Embodiment 1 of this invention.

  Hereinafter, preferred embodiments of an antenna feeding circuit of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a configuration of an antenna feeding circuit according to Embodiment 1 of the present invention. The antenna feeding circuit shown in FIG. 1 includes a common terminal 1, a high band terminal 2, four low band branch terminals 3a to 3d, a common waveguide 4, a high band waveguide (circular) 5, and four low bands. Band-band branching waveguides 6a to 6d, a four-branch circuit 7, and a high-band waveguide (rectangular) 8 are provided.

  The common waveguide 4 and the high band waveguide (circular) 5 are connected via the four branch circuit 7 and the high band waveguide (rectangular) 8. A common terminal 1 is provided at one end of the common waveguide 4, and a high-band terminal 2 is provided at one end of the high-band waveguide (circular) 5.

  Further, four ends of the low-band branch waveguides 6a to 6d are connected to the tube wall of the four-branch circuit 7 at intervals of 90 degrees in the circumferential direction through coupling holes. At this time, the low-frequency band branching waveguides 6a to 6d are provided with a low-pass filter disposed close to the four-branch circuit 7. Further, low-band branch terminals 3a to 3d are provided at the other ends of the low-band branch waveguides 6a to 6d.

  In the first embodiment, the common waveguide 4 and the high-band waveguide (circular) 5 are circular, and the low-band branching waveguides 6a to 6d are rectangular. Yes. However, the high-band waveguide (circular) 5 is a circular waveguide, but may be a rectangular waveguide.

  The wide surfaces of the low-band branching waveguides 6a to 6d are provided so as to be perpendicular to the tube axis direction. Further, the connection portions of the low-band branch waveguides 6 a to 6 d to the four-branch circuit 7 are installed so as to be perpendicular to the tube axis direction of the high-band waveguide 8. Note that the low-band branch terminals 3c and 3d do not appear in FIG.

  FIG. 2 is a perspective view showing the low-band branching waveguide 6 according to the first embodiment of the present invention. The four low-band branching waveguides 6a to 6d shown in FIG. 1 have the same shape, and are shown as the low-band branching waveguide 6 in FIG. The low-band branching waveguide is bent in a direction parallel to the high-band waveguide axis for miniaturization. As shown in FIG. 2, the filter in the low-band branching waveguide 6 is functionally provided with a filter unit 61 (hereinafter referred to as a vertical-portion filter unit 61) installed in a vertical part with respect to the high-band waveguide axis. ) And a filter part 62 (hereinafter referred to as a parallel part filter part 62) installed in a parallel part with respect to the high-band waveguide axis.

  The vertical filter unit 61 is connected via the coupling hole so that the connection to the four-branch circuit 7 is perpendicular to the tube axis direction of the high-band waveguide 8. Further, the horizontal filter unit 62 disposed at the connection destination of the vertical filter unit 61 is connected in a direction parallel to the tube axis direction of the high-band waveguide 8. In order to suppress the deterioration of characteristics due to high-band signals entering the branching waveguide, the vertical filter unit 61 is disposed near the four-branch circuit connecting part in the branching waveguide.

  Next, a specific operation of the antenna feeding circuit according to the first embodiment will be described. FIG. 3 is an operation explanatory diagram of the antenna feeding circuit according to Embodiment 1 of the present invention. In FIG. 3, a longitudinal section in the tube axis direction passing through the low-band branch waveguide 6a and the low-band branch waveguide 6c facing each other at a position of 180 ° with the low-band branch waveguide 7 interposed therebetween. The figure is shown. However, in the following, all the low-band branching waveguides 6a to 6d will be described.

  When orthogonally polarized waves in the low frequency band are input from the low frequency band branch terminals 3a to 3d, this low frequency band signal (low frequency band signal) flows as indicated by solid arrows in FIG. Will be along. That is, the low frequency band signal is input from the low frequency band branch terminals 3a to 3d of the low frequency band branch waveguides 6a to 6d, and is connected to the common terminal via the four branch circuit 7 and the common waveguide 4. 1 is output. Here, the signal is cut off in the direction of the high-frequency band terminal 2 via the four-branch circuit 7 because it is cut off from the size of the high-frequency waveguide 8.

  On the other hand, when orthogonal polarized waves in the high frequency band are input from the common terminal 1, this high frequency band signal (wide band signal) follows the flow indicated by the dotted arrow in FIG. Become. That is, the high-band signal passes through the common waveguide 4, the four-branch circuit 7, the high-band waveguide (rectangular) 8, and the high-band waveguide (circular) 5 to the high-band terminal. 2 is output.

  At this time, the low-frequency branch waveguides 6 a to 6 d are connected to the four-branch circuit 7. However, each of the low-band branching waveguides 6 a to 6 d has a configuration including a low-pass filter unit 61. As described above, since the low-pass filter unit 61 is provided, the high-band signal is not transmitted to the rectangular branch waveguides 6a to 6d.

  By bending the low-band branch waveguide so that it is parallel to the high-band waveguide axis and dividing the vertical and parallel filter sections of the low-band branch waveguide, the high-band The outer diameter of the antenna feeding circuit can be reduced while maintaining the blocking performance.

Embodiment 2. FIG.
In the second embodiment, the parallel filter section is a band rejection filter. The band rejection filter has a one-sided stub structure, and has a structure in which the convex portion of the stub faces the high-band waveguide side.

  1 and 2 show the structure. FIG. 4 is a diagram showing an example of filter characteristics of the low-band branching waveguides 6a to 6d in the second embodiment of the present invention. Specifically, FIG. 4 shows that when a signal is input from the common terminal 1 in the low frequency band, from the low band branch terminals 3a to 3d via the low band branch waveguides 6a to 6d. It is a characteristic view which shows the filter performance of the signal output.

  A low-pass filter unit 61 that cuts off the polarization in the high-frequency band is loaded, and the configuration of a conventional rectangular branch waveguide without the band-stop filter unit 62 and the low-pass filter unit 61 are loaded and the band FIG. 4 shows a comparison of the filter performance of the configurations of the low-band branching waveguides 6a to 6d according to the first embodiment in which the blocking filter unit 62 is provided.

  In FIG. 4, the characteristic indicated by the dotted line is a characteristic according to the conventional configuration in which the band rejection filter unit 62 is not provided, and the characteristic illustrated by the solid line is according to the configuration of the first embodiment in which the band rejection filter unit 62 is provided. It is a characteristic. In the characteristic shown by the dotted line in which the band rejection filter unit 62 is not provided, the filter characteristic 21 is slow. On the other hand, the steep filter characteristic 22 is obtained in the characteristic shown by the solid line in which the band rejection filter unit 62 is provided.

  As described above, according to the first and second embodiments, the circuit having the function of a low-pass filter is bent halfway, and the circuit having the function of the band rejection filter is loaded at the connection destination. By adopting such a configuration, the length of the low-pass filter circuit protruding from the outer portion is shortened and the outer portion of the circuit is reduced in size while having the band rejection characteristic of the subsequent band elimination filter. be able to. That is, it is possible to obtain an antenna feeding circuit that has a sufficient cutoff performance for high-frequency signals and is smaller than the conventional device.

  Furthermore, the outer diameter of the antenna feeding circuit can be further reduced by configuring the convex portion for realizing the function of the band rejection filter so as to face the tube wall side of the high band waveguide.

  FIG. 1 shows a configuration in which a corrugated low-pass filter is loaded as an example of the first low-band branching waveguides 6a to 6d. However, the low-band branching waveguides 6a to 6d are not limited to this configuration, and may be loaded with a waffle iron type low-pass filter or the like. Further, an iris or other matching element may be provided in the coupling hole which is a connection portion between the low-band branching waveguides 6a to 6d and the four-branch circuit 7.

  1 common terminal, 2 high band terminal, 3a to 3d low band branch terminal, 4 common waveguide, 5 high band waveguide (circular), 6, 6a to 6d low band branch waveguide, 7 4-branch circuit, 8 high-band waveguide (rectangular), 61 filter section installed in the vertical section with respect to the high-band waveguide axis of the low-band branch waveguide, 62 low-band branch waveguide A filter unit installed in a parallel part with respect to the high band waveguide axis of the tube.

Claims (2)

An antenna feeding circuit configured to include a high-band waveguide that allows a high-frequency signal to pass through and a waveguide that includes a four-branch circuit that demultiplexes and synthesizes a low-frequency signal. Each of the branching waveguides connected to the circuit has a waveguide extending in a direction perpendicular to the tube axis direction of the high band waveguide and parallel to the tube axis direction of the high band waveguide. A low-pass filter section having a low-pass function is loaded near the connection with the four-branch circuit, and the waveguide is bent before the high-pass waveguide axis. Antenna feed circuit loaded with parallel filter parts that are parallel to each other. The band section filter is used as the parallel section filter section, and the convex section for realizing the function of the band stop filter is configured to face the tube wall side of the high band waveguide. The antenna feeding circuit described.

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