JPH07288403A - Higher-order mode coupler - Google Patents

Abstract

PURPOSE:To provide the miniaturized, lightened and one-hole higher-order mode coupler which can fetch signals at different frequencies as a differential signal. CONSTITUTION:At a circular main waveguide 1, a tapered part 4 is formed to change a diameter dimension so that a cut-off area 5 in a desired higher-order mode 9 can exist, a coupling hole 6 provided in the circumferential direction of the main waveguide 1 is arranged on the wall surface of the main waveguide at a position away from the cut-off area 5 to the large diameter side just for nlambdag'/4 (lambdag' is the in-pipe wavelength in this higher-order mode and (n) is an odd number) and a rectangular sub waveguide 7 is connected to each coupling hole 6. A standing wave 11 in the higher-order mode 9 is generated by the cut-off area 5, and the coupling amount of the higher-order mode at the coupling hole 6 provided at the peak position of this standing wave 11 is increased. Since the tapered part and the coupling holes are suitably designed, the higher- order mode coupler can be provided to fetch the differential signal even from the frequencies of different reception bands.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-order mode monopulse tracking system used in a large antenna device for satellite communication, and more particularly to a higher-order mode coupler for extracting a difference signal such as a beacon frequency of a satellite.

[0002]

2. Description of the Related Art Conventionally, a porous high-order mode coupler has been used as an element for efficiently extracting a higher-order mode generated in a large antenna device for satellite communication. For example, FIG. 4 is disclosed in Japanese Patent Application Laid-Open No. 61-135201, and its structure is such that a plurality of circular main waveguides 21 are arranged in the axial direction at a plurality of positions on the wall surface in the circumferential direction. Row 22 of coupling holes is provided, and each of these row 22 of coupling holes is provided with a rectangular sub-waveguide 23 coupled by the E-plane or the H-plane.

This porous high-order mode coupler is designed so that the propagation constant of the desired higher-order mode propagating in the main circular waveguide 21 and the propagation constant of the TE10 mode in the rectangular sub-waveguide are equal. Choosing a wave tube shape. In addition, the main circular waveguide 2 is used as the main signal by reducing the amount of coupling per coupling hole.
The TE11 mode propagating in 1 is prevented from coupling (leaking) into the sub-waveguide 23, and the coupling hole intervals of the plurality of coupling hole rows are set to about λg ′ / 4 (λg ′: desired higher order mode). As the (wavelength in the main circular waveguide), the directivity of the higher-order mode coupled in the sub-waveguide, the coupling amount, and the degree of separation from the TE11 mode are obtained.

However, in the high-order mode coupler having this structure, a large number of coupling holes are required to obtain a desired coupling amount, and the sub-waveguide is connected to these coupling holes. , The width of the main circular waveguide increases over substantially the entire length, and the weight of the sub-waveguide increases,
There is a problem that the structure becomes large and heavy.

For this reason, a single-hole type higher-order mode coupler has been proposed which allows only the beacon frequency of the satellite used as the difference signal to pass. For example, in the configuration of FIG. 5, one coupling hole 32 is provided at each of two locations in the circumferential direction of the circular main waveguide 31, and the rectangular sub-waveguide 3 is provided in each coupling hole 32.
3 is connected. Then, in the sub-waveguide 33,
A high Q filter 34 is provided to pass only the difference signal.

Here, the single-hole high-order mode coupler is a TE
Since the degree of separation between the 11-mode and the higher-order mode is determined only by the difference in the coupling amount of each mode, the coupling (leakage) of the TE11 mode to the sub-waveguide 33 can be reduced as in the porous type. Can not. Therefore, by providing the high-Q filter 34 that passes only the satellite beacon wave as the difference signal, it is possible to reduce the amount of leakage in the TE11 mode in other frequency bands and prevent the loss. Further, the sub-waveguide 33 can be downsized, which is advantageous for downsizing and weight reduction of the coupler.

[0007]

However, in this short-hole type higher-order mode coupler, since the dedicated high-Q filter 34 corresponding to the satellite beacon frequency as the difference signal is used, the satellite beacon When the frequency is changed, it is practically impossible to extract the difference signal.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to employ a single-hole type coupler to reduce the size and weight of the sub-waveguide without providing a high-Q filter for transmitting only beacon waves. , It is to provide a high-order mode coupler capable of extracting signals at all reception frequencies as difference signals.
Another object of the present invention is to provide a high-order mode combiner capable of effectively blocking a transmission band signal.

[0009]

The higher-order mode coupler of the present invention has its diameter gradually changed so that the circular main waveguide has a desired higher-order mode cutoff region to be coupled. The coupling hole formed in the circumferential direction of the main waveguide is formed from the cutoff region to the larger diameter nλg ′ / 4 (λg ′ is the inside of the high-order mode pipe in the tapered waveguide). It is arranged on the wall surface of the main waveguide at a position separated by a wavelength and n is an odd number, and a rectangular sub-waveguide is connected to each coupling hole.

Here, the coupling holes are arranged on the wall surface of the main waveguide at a position λg ′ / 4 away from the cutoff region in the larger diameter direction, and at four or eight positions in the circumferential direction of the main waveguide. It is preferable that they are provided at equal positions. Further, the coupling hole is provided with a resonance element that resonates with the transmission band signal, the rectangular sub-waveguide is provided with a filter for blocking the transmission band signal, and the H surface in the rectangular sub-waveguide is provided. It is preferable to provide a radio wave absorber that is effective in the transmission band.

[0011]

In the higher mode coupler of the present invention, a standing wave of a higher mode is generated in the main waveguide by forming a tapered portion having a diameter that cuts off the desired higher mode in the main waveguide. In addition, since the coupling hole is provided at the position where the standing wave has the strongest coupling, the coupling amount of the higher-order mode is made larger than that of the coupling of only the forward wave. Accordingly, by appropriately designing the tapered portion and the coupling hole, it is possible to realize a compact high-order mode coupler capable of extracting a difference signal for any frequency in the reception band.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view of a first embodiment of a higher mode coupler of the present invention, and FIG. 2 is a sectional view taken along the axial direction thereof. In these figures, the circular main waveguide 1 is configured as a circular tapered waveguide having a desired higher-order mode cutoff region. That is, it is configured as a circular tapered waveguide that is tapered along the axial direction such that the diameter dimension thereof gradually increases from the power feeding portion side opening 2 toward the horn side opening 3.
The diameter of the tapered portion 4 of the main waveguide 1 is designed to be changed within a range including the diameter of the cutoff region 5 of the desired higher-order mode to be coupled. There is.

The desired higher-order mode cutoff region 5
To the horn side opening 3 with a large diameter from the position of λg '/
4 (λg ': guide wavelength of higher-order modes in the tapered waveguide) On a wall surface apart from each other, a single coupling hole (in the axial direction, at a plurality of locations symmetrical to the circumferential direction of the main waveguide, here four locations) A row of connecting holes) 6 is opened. Then, on the outer peripheral surface of the main waveguide 1, rectangular sub-waveguides 7 are radially connected in the coupling holes 6, respectively, and by connecting these rectangular sub-waveguides 7 to each other. The higher order modes are combined to extract the difference signal.

According to this configuration, referring to FIG. 2, the TE11 mode 8 and the higher-order modes 9 in the received wave incident on the main waveguide 1 through the horn-side opening 3 propagate through the main waveguide 1. At this time, a part of TE11 mode 8 as a forward wave passes through the coupling hole 6 and is coupled to the sub-waveguide 7, but most of the TE11 mode 8 is propagated as it is to the opening 2 on the feeder side. On the other hand, higher mode 9
Is totally reflected toward the horn-side opening 3 in the cutoff region 5 generated in the tapered portion of the main waveguide 1, and as a result, the main waveguide 1
A standing wave 10 is generated inside.

Since the main waveguide 1 is provided with a coupling hole 6 at a position λg '/ 4 with respect to the guide wavelength of the higher mode 9 from the cutoff region 5, the standing wave 10 has a The coupling to the higher mode 9 is performed by the coupling hole 6 at the position where the coupling is strongest. This coupling can be stronger than the forward wave only coupling. This makes it possible to extract the difference signal from the rectangular sub-waveguide 7.

Further, in this configuration, since the cutoff region in the main waveguide 1 is changed according to the frequency of the higher order mode 9, by appropriately setting the shape of the tapered portion 4 of the main waveguide 1. The strongest position of the standing waves of different frequencies can be matched with the coupling hole 6, and the difference signal can be taken out for any frequency in the reception band. Further, depending on the case, it is possible to provide a coupling hole at the peak position of the second wave of the standing wave, but if provided at the peak position of the first wave as in the above embodiment, the coupling hole This is advantageous in shortening the axial length.

In this case, the amount of leakage in the TE11 mode is slightly larger than that in the porous mode coupler.
It cannot be denied that the mode loss will increase, but with the recent increase in satellite EIRP, it is possible to sufficiently cope with the G / T on the earth station side without improving its performance.

FIG. 3 is a perspective view of the second embodiment of the present invention, in which the same parts as those in the first embodiment are designated by the same reference numerals.
Also in this second embodiment, a circular taper waveguide is used as the main waveguide 1, and the taper is changed so that its diameter is changed within a range including a diameter in which a cutoff region of a desired higher-order mode to be coupled is generated. The shaped part 4 is formed. Further, at the wall surface λg ′ / 4 away from the position of the desired higher-order mode cutoff region in the direction of the horn side opening 3 having a large aperture, the main waveguide 1
A single coupling hole 6 is formed at each of four locations that are symmetrical in the circumferential direction. Then, on the outer peripheral surface of the main waveguide 1, rectangular sub-waveguides 7 are radially connected in the coupling holes 6, respectively, and by connecting these rectangular sub-waveguides 7 to each other. The higher order modes are combined to extract the difference signal.

Further, in the second embodiment, each rectangular sub-waveguide 7 is provided with a transmission band blocking filter 12 for blocking a signal in the transmission band by arranging a plurality of walls on the inner wall thereof. I am configuring. Further, a radio wave absorber 13 effective in the transmission band is attached to the H surface in the rectangular sub-waveguide 7. Further, the coupling hole 6 itself is also provided with a resonance element 14 that resonates with a signal in the transmission band to reduce the amount of coupling of the transmission band signal.

Also in this configuration, similarly to the first embodiment, the TE11 mode and the higher-order modes in the received wave incident on the main waveguide 1 through the horn side opening 3 propagate through the main waveguide 1 and the TE11 mode changes. Part of the forward wave is the coupling hole 6
Although it is coupled to the sub-waveguide 7 through, it is almost directly propagated to the opening 2 on the feeder side. Further, the higher-order modes are totally reflected toward the horn-side opening 3 in the cutoff region generated in the tapered portion 4 of the main waveguide 1, and as a result, a standing wave is generated in the main waveguide 1.

Then, the coupling hole 6 couples to the higher-order mode at the position where the standing wave is most strongly coupled, and the difference signal can be taken out from the rectangular sub-waveguide 7. Further, in this case, since the coupling hole 6 is provided with the resonance element 14 which resonates with the signal in the transmission band, and the rectangular sub-waveguide 7 is provided with the transmission band filter 12, the transmission wave is rectangular. Leakage to the wave tube 7 is prevented. Further, since the electromagnetic wave absorber 13 effective in the transmission band is provided, the transmission wave leaking from the coupling hole 6 is apt to be generated between the coupling hole 6 and the transmission band filter 12 due to confinement resonance. It is possible to prevent deterioration.

Here, the shape of the tapered portion formed in the main waveguide may be either a configuration in which the diameter dimension changes linearly or a configuration in which the diameter dimension changes in a curved line,
By appropriately setting the shape, the coupling hole can be commonly used for higher-order modes of different frequencies as described above. Further, although the above-mentioned embodiment shows an example in which the coupling hole and the sub-waveguide are arranged at four positions in the circumferential direction of the main waveguide, it is assumed that the coupling hole and the sub-waveguide are arranged at eight positions. Good. By increasing this number, the total binding amount can be increased,
It is not preferable in terms of downsizing and weight reduction of the structure of the coupler.

[0023]

As described above, according to the present invention, a circular main waveguide is formed with a tapered portion whose diameter is gradually changed so that a desired high-order mode cutoff region exists. Since the coupling hole is provided at the position where the standing wave of the higher-order mode generated by the cutoff region has the strongest coupling, the coupling amount of the higher-order mode is made larger than that in the case of coupling only the forward wave. Therefore, by properly designing the tapered portion and the coupling hole, it is possible to extract the difference signal at any frequency in the reception band, and the small-sized and lightweight high-performance that is characteristic of the single-hole type coupler. A second mode combiner can be realized.

Particularly, since the coupling hole is arranged on the wall surface of the main waveguide at a position λg ′ / 4 away from the cutoff region in the direction of the larger diameter, the peak position of the first wave of the standing wave is obtained. The coupling hole can be located, the coupling hole can be provided at a position close to the cutoff region, and the length of the main waveguide can be shortened.

Further, the coupling hole is provided with a resonance element which resonates with the transmission band signal, the rectangular sub-waveguide is provided with a filter for blocking the transmission band signal, and H in the rectangular sub-waveguide is provided. By providing a radio wave absorber that is effective in the transmission band on the surface,
It is possible to prevent the transmitted wave from being coupled and leak to the sub-waveguide, and to prevent characteristic deterioration due to confinement resonance.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a first embodiment of a higher mode coupler according to the present invention.

FIG. 2 is a cross-sectional view in the axial direction of FIG. 1 and is a view for explaining a standing wave in a higher-order mode.

FIG. 3 is a partially cutaway perspective view of a second embodiment of the present invention.

FIG. 4 is a perspective view of an example of a conventional porous high-order mode coupler.

FIG. 5 is a perspective view of an example of a conventional single-hole high-order mode coupler.

[Explanation of symbols]

 1 circular main waveguide 4 tapered portion 5 cutoff region 6 coupling hole 7 rectangular sub-waveguide 8 TE11 mode 9 higher mode 11 standing wave 12 transmission band stop filter 13 electromagnetic wave absorber 14 resonant element

Claims (5)

[Claims] 1. A high-order mode coupler comprising a circular main waveguide and a plurality of rectangular sub-waveguides connected through a plurality of coupling hole rows provided in the circumferential direction of the wall surface of the circular main waveguide. Is formed with a tapered portion whose diameter is gradually changed so that there exists a desired higher-order mode cutoff region to be coupled, and the coupling hole is nλg from the cutoff region toward the larger diameter. A high-order mode coupler, which is disposed on a wall surface of a main waveguide at a position separated by '/ 4 (λg' is a guide wavelength of the higher-order mode in the tapered waveguide, n is an odd number). 2. The coupling hole has a diameter λ from the cutoff region toward the larger diameter.
The high-order mode coupler according to claim 1, which is disposed on a wall surface of the main waveguide at a position separated by g '/ 4. 3. The high-order mode coupler according to claim 1, wherein the coupling holes are provided at four or eight equally distributed positions in the circumferential direction of the main waveguide. 4. The coupling hole is provided with a resonance element which resonates with a transmission band signal, and the rectangular sub-waveguide is provided with a filter for blocking the transmission band signal. Higher-order mode coupler 5. The high-order mode coupler according to claim 4, wherein an electromagnetic wave absorber effective in the transmission band is provided on the H-plane in the rectangular sub-waveguide.