JP2024032077A - Filter device, transmitter, and radar - Google Patents

Abstract

To provide a filter device capable of suppressing harmonics.SOLUTION: A filter device includes a resonator with an adjustment unit that propagates a fundamental wave and harmonics of the fundamental wave and is equipped with the adjustment unit that adjusts a phase of the harmonics to an opposite phase, and is formed with a first propagation path passing through the resonator with the adjustment unit and a second propagation path not passing through the resonator with the adjustment unit, and combines the harmonics propagating through the first propagation path adjusted to have opposite phases and the harmonics propagating through the second propagation path.SELECTED DRAWING: Figure 2

Description

The present invention relates to a filter device, a transmitter, and a radar.

Generally, in a filter device, not only the fundamental wave but also its harmonics resonate, so in order to suppress the harmonics, a low-pass filter that attenuates higher frequency components than the fundamental wave is often used in combination ( For example, Patent Document 1).

Japanese Patent Application Publication No. 59-8401

However, the method of using a low-pass filter in combination has the problem of increased loss due to a longer path and larger equipment.

The present invention has been made in view of the above problems, and its main purpose is to provide a filter device capable of suppressing harmonics, and a transmitter and radar equipped with the filter device.

In order to solve the above problems, a filter device according to one aspect of the present invention includes an adjustment section that propagates a fundamental wave and a harmonic of the fundamental wave and that is provided with an adjustment section that adjusts the phase of the harmonic to an opposite phase. a first propagation path that passes through the resonator with an adjustment section and a second propagation path that does not go through the resonator with an adjustment section; The phase-adjusted harmonics and the harmonics propagating through the second propagation path are combined. According to this, it becomes possible to suppress harmonics.

In the above aspect, the second propagation path further includes an upstream resonator disposed upstream of the resonator with an adjustment section, and a downstream resonator disposed downstream of the resonator with an adjustment section, and the second propagation path A coupling path may be included for coupling the upstream resonator and the downstream resonator. According to this, it becomes possible to suppress harmonics while obtaining a steep passage characteristic for the fundamental wave by jump coupling between the resonators.

In the above aspect, the resonator with adjustment section, the upstream resonator, and the downstream resonator may be waveguide resonators that resonate the fundamental wave in a TE mode. According to this, in the waveguide resonator, it is possible to suppress harmonics while obtaining steep passage characteristics for the fundamental wave.

In the above aspect, the two resonators with adjustment parts are separated by a partition wall serving as an E plane, and the coupling window formed in the partition wall propagates a part of the harmonics adjusted to have an opposite phase. Good too. According to this, it becomes possible to adjust the amount of propagation of harmonics adjusted to have opposite phases in the first propagation path.

In the above aspect, the upstream resonator and the downstream resonator may be separated by a partition wall serving as an E plane, and a coupling window serving as the coupling path formed in the partition wall may propagate a part of the harmonic wave. . According to this, it becomes possible to adjust the amount of harmonic propagation in the second propagation path.

In the above aspect, the second propagation path further includes another resonator disposed upstream or downstream of the resonator with an adjustment section, and the second propagation path includes a filter section including the resonator with an adjustment section and the other resonator. may be formed independently. According to this, harmonics can be suppressed by the second propagation path independent of the filter section.

In the above aspect, the second propagation path may propagate only the harmonics among the fundamental wave and the harmonics. According to this, it is possible to suppress harmonics by propagating only harmonics.

Further, a transmitter according to another aspect of the present invention includes the above filter device. According to this, it becomes possible to provide a filter device that realizes suppression of harmonics.

Further, a radar according to another aspect of the present invention includes the above filter device. According to this, it becomes possible to provide a filter device that realizes suppression of harmonics.

FIG. 2 is a diagram showing an example of the configuration of a radar. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing an example of composition of a filter device. It is a figure showing a reference example of a filter device.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a radar 100 according to an embodiment. The radar 100 is an example of a transmitter according to the embodiment, and is a microwave transceiver that transmits and receives microwaves. The radar 100 includes a waveguide filter 1 as an example of a filter device according to an embodiment.

In addition to the waveguide filter 1, the radar 100 includes a magnetron 91, a pulse drive circuit 92, a circulator 93, a terminator 94, a circulator 95, a rotary joint 96, an antenna 97, a limiter circuit 98, and a receiving circuit 99.

The magnetron 91 is a microwave generator that oscillates, for example, a 9.4 GHz microwave as a fundamental wave. The pulse drive circuit 92 drives the magnetron 91 intermittently at a predetermined period to generate a pulsed transmission signal. The circulator 93 switches the output destination of the pulsed transmission signal from the magnetron 91.

Waveguide filter 1 is interposed between magnetron 91 and antenna 97. In this embodiment, the waveguide filter 1 is configured as a bandpass filter, allowing passage of a fundamental wave and suppressing passage of harmonics with respect to the fundamental wave. The suppressed harmonics are consumed in a terminator 94 connected to a circulator 93.

Circulator 95 outputs the transmitted signal from waveguide filter 1 to antenna 97 and outputs the received signal from antenna 97 to receiving circuit 99. The rotary joint 96 is interposed between the antenna 97 and the circulator 95, and electrically connects the rotating system and the stationary system.

The antenna 97 is rotated by a motor (not shown), transmits a transmission signal as a radio wave pulse, and converts a received reflected wave into a reception signal. The limiter circuit 98 suppresses a high level received signal immediately after the start of reception. Receiving circuit 99 acquires a received signal from antenna 97.

The path from the magnetron 91 to the antenna 97 is composed of a waveguide. Further, the path from the antenna 97 to the limiter circuit 98 is also formed of a waveguide.

In this embodiment, the radar 100 to which the waveguide filter 1 is applied is a marine radar that transmits and receives microwaves, but is not limited to this, but is, for example, a vehicle-mounted radar that transmits and receives millimeter waves for obstacle detection or collision prevention. It may also be a radar or the like.

FIG. 2 is an exploded perspective view showing a configuration example of the waveguide filter 1. As shown in FIG. The waveguide filter 1 includes two blocks 2 and 3 and a partition plate 4 sandwiched between them.

FIG. 3 is a diagram showing an example of the configuration of the block 2, and is a diagram of the block 2 viewed from the partition plate 4 side. FIG. 4 is a diagram showing an example of the configuration of the block 3, and is a diagram of the block 3 viewed from the partition plate 4 side.

FIG. 5 is a diagram showing an example of the configuration of the partition plate 4, and is a diagram of the partition plate 4 viewed from the block 3 side. FIG. 6 is a diagram showing a cross section of the block 2 taken along the line VI-VI shown in FIG.

The Z direction in the figure represents the thickness direction or stacking direction of the blocks 2 and 3 and the partition plate 4. The X direction and the Y direction represent the lateral direction and longitudinal direction of the blocks 2 and 3 and the partition plate 4, respectively, in a plane orthogonal to the Z direction.

The blocks 2 and 3 and the partition plate 4 are made of metal. Specifically, the blocks 2 and 3 are made of a conductive metal material such as aluminum. The partition plate 4 is also made of a conductive metal material such as an aluminum alloy.

The blocks 2 and 3 sandwich the partition plate 4, with the opposing surface 29 of the block 2 in contact with one main surface of the partition plate 4, and the opposing surface 39 of the block 3 in contact with the other main surface of the partition plate 4. The blocks 2 and 3 and the partition plate 4 are fastened together by fastening members such as screws (not shown).

As shown in FIG. 3, a recess 20 for radio wave propagation is formed in the opposing surface 29 of the block 2. The recess 20 includes two resonance regions 21 and 22 arranged in the Y direction and a coupling window 23 interposed between them. The resonance region 22 has adjustment sections 221 and 222 for adjusting harmonics.

A coupling window 25 is formed at the bottom of the resonant region 21 of the block 2 to communicate the resonant region 21 with the outside. An input waveguide line 82 (see FIG. 2) is connected to the coupling window 25, and radio waves are input from the waveguide line 82 to the resonance region 21 through the coupling window 25.

As shown in FIG. 4, a recess 30 for radio wave propagation is formed in the opposing surface 39 of the block 3. The recess 30 includes two resonance regions 31 and 32 arranged in the Y direction and a coupling window 33 interposed between them. The resonance region 31 has adjustment sections 311 and 312 for adjusting harmonics.

A coupling window 35 is formed at the bottom of the resonant region 32 of the block 3 to communicate the resonant region 32 with the outside. An output waveguide line 83 (see FIG. 2) is connected to the coupling window 35, and radio waves are output from the resonance region 32 to the waveguide line 83 through the coupling window 35.

As shown in FIG. 5, a plurality of coupling windows 41-45 are formed in the partition plate 4. The partition plate 4 is sandwiched between the blocks 2 and 3 and is interposed between the recesses 20 and 30. That is, the partition plate 4 covers both the recess 20 and the recess 30. In this embodiment, the recesses 20 and 30 have a mirror-symmetrical relationship.

The coupling windows 41-44 communicate the resonant region 22 of block 2 and the resonant region 31 of block 3. The coupling window 45 allows the resonance region 21 of the block 2 and the resonance region 32 of the block 3 to communicate with each other.

By assembling and fastening the blocks 2, 3 and the partition plate 4, each resonance region 21, 22, 31, 32 functions as a waveguide type resonator. In this embodiment, the waveguide filter 1 includes a total of four waveguide resonators. Each resonance region 21, 22, 31, 32 has a predetermined dimension determined based on the frequency of the radio wave (electromagnetic wave) used.

Each of the resonance regions 21, 22, 31, and 32 has a flat shape in which the dimension in the Z direction is shorter than the dimensions in the X and Y directions, and causes radio waves to resonate in the TE mode. The electric field vector of the resonant radio waves points in the Z direction. The dimension of each resonance region 21, 22, 31, 32 in the X direction (radio wave propagation direction) is, for example, about 1/2 of the wavelength of the fundamental wave.

FIG. 7 is a diagram schematically showing a configuration example of the waveguide filter 1. As shown in FIG. As shown in the figure, the waveguide filter 1 includes a first propagation path P1 passing through resonance regions 22, 31 provided with adjustment sections 221, 222, 311, 312, and A second propagation path P2 that does not pass through is formed.

The resonance regions 22 and 31 are examples of resonators with adjustment sections. Resonant region 21 located upstream of resonant regions 22 and 31 is an example of an upstream resonator. Resonant region 32 located downstream of resonant regions 22, 31 is an example of a downstream resonator.

The resonance regions 22 and 31 are separated by the partition plate 4, and the resonance regions 22 and 31 are also separated by the partition plate 4 (see FIG. 2). The partition plate 4 is an example of a partition wall, and serves as the E plane of the resonance regions 21, 22, 31, and 32. The E plane is a plane orthogonal to the electric field vector (Z direction) of the resonating fundamental wave.

The first propagation path P1 is a path passing through the resonance regions 21, 22, 31, and 32 in order. Specifically, in the first propagation path P1, the radio waves pass through the coupling window 25, the resonance region 21, the coupling window 23, the resonance region 22, the coupling windows 41-44, the resonance region 31, the coupling window 33, the resonance region 32, and It propagates in the order of the combination window 35.

The second propagation path P2 is a path that passes through the resonance regions 21 and 32 in order, but does not pass through the resonance regions 22 and 31. Specifically, in the second propagation path P2, the radio wave propagates through the coupling window 25, the resonance region 21, the coupling window 45, the resonance region 32, and the coupling window 35 in this order. The coupling window 45 is an example of a coupling path.

A fundamental wave and its harmonics (multiple waves) propagate in the first propagation path P1 and the second propagation path P2. , 311 and 312, the phase of the harmonics is adjusted to be in opposite phase.

Therefore, the harmonics propagating through the first propagation path P1 adjusted to have opposite phases and the harmonics propagating through the second propagation path P2 are combined in the resonance region 32, thereby suppressing the passage of the harmonics. Ru. In other words, the waveguide filter 1 becomes a band-pass filter that allows the passage of the fundamental wave and suppresses the passage of harmonics.

The adjustment units 221, 222, 311, and 312 provided in the resonance regions 22 and 31 of the first propagation path P1 are spaces into which the fundamental wave cannot enter, but harmonics can enter (Figs. 3 and 4 ), it is possible to adjust the phase of the harmonics while leaving the fundamental wave unchanged.

The width (length in the X direction) of the adjustment sections 221, 222, 311, and 312 may be, for example, 1/2 or less of the wavelength of the fundamental wave and 1/2 or more of the wavelength of the harmonic (second harmonic). preferable.

Furthermore, the depths (lengths in the Y direction) of the adjustment sections 221, 222, 311, and 312 are factors that determine the amount of phase shift of the harmonics, so they are adjusted so that the phases of the harmonics are opposite to each other. . The depth of the adjusting portions 221, 222, 311, and 312 is preferably adjusted within a range of, for example, 1/5 or more and 1/3 or less of the wavelength of the harmonic (secondary harmonic).

The coupling windows 41-44 formed between the resonant regions 22 and 31 propagate a portion of the harmonics adjusted to have opposite phases. That is, the coupling windows 41-44 adjust the amount of coupling between the harmonic mode of the resonance region 22 and the harmonic mode of the resonance region 31.

The coupling windows 41 and 42 are formed at positions where harmonic modes are mainly coupled with each other by electric fields, and the coupling windows 43 and 44 are formed at positions where harmonic modes are mainly coupled with each other by magnetic fields. The amount of harmonic propagation is adjusted by adjusting the positions of the coupling windows 41-44 to create a difference between the amount of electric field coupling and the amount of magnetic field coupling.

In the second propagation path P2, the resonance regions 21 and 32 are directly coupled by the coupling window 45, thereby improving the filter characteristics. In this embodiment, an elliptic function filter that utilizes jump coupling between resonators is configured. An elliptic function filter exhibits a steep passage characteristic called a pole by coupling input and output.

A coupling window 45 formed between the resonant regions 21 and 32 propagates a portion of the harmonics. The coupling window 45 is formed at the center of the E plane of the resonance regions 21 and 32. That is, the center of the E plane exists inside the coupling window 45.

In other words, the electric field of the fundamental wave is concentrated at the center of the E plane, but the electric field of the harmonics is not so concentrated. Therefore, by forming the coupling window 45 at the center of the E plane, almost all of the fundamental wave is concentrated. While all will propagate, only some of the harmonics will propagate.

The coupling windows 41-44 formed between the resonance regions 22 and 31 and the coupling window 45 formed between the resonance regions 21 and 32 allow the propagation of harmonics adjusted to have the opposite phase of the first propagation path P1. The position and size are adjusted so that the amount and the amount of harmonic propagation on the second propagation path P2 are approximately equal.

According to the embodiment described above, the first propagation passes through the resonance regions 22 and 31 in which the waveguide filter 1 is provided with adjustment sections 221, 222, 311, and 312 that adjust the phase of harmonics to opposite phases. By forming the path P1 and the second propagation path P2 that does not go through the resonance regions 22 and 31, it is possible to suppress harmonics while allowing passage of the fundamental wave.

Furthermore, in the second transmission path P2, the resonance regions 21 and 32 are directly coupled by the coupling window 45, thereby configuring an elliptic function filter that utilizes jump coupling between the resonators, resulting in a steep passage of the fundamental wave. It becomes possible to obtain the characteristics.

As shown in the reference example of FIG. 9, there is also a method of suppressing all harmonics by not coupling the harmonic modes of the resonance region 22 and the harmonics of the resonance region 31 with the coupling windows 41-44. In this case, if the resonance regions 21 and 32 are coupled, harmonics will pass through, so it is not possible to couple them.

On the other hand, in the present embodiment shown in FIG. 7, instead of suppressing all harmonics in the first propagation path P1, the phases of the harmonics are adjusted to have opposite phases, so that the resonance regions 21 and 32 are They can be combined to form a second propagation path P2, thereby making it possible to obtain steep passage characteristics for the fundamental wave while suppressing the passage of harmonics.

Next, a modification shown in FIG. 8 will be described. Configurations that overlap with those of the above embodiments may be given the same numbers and detailed explanations may be omitted. The filter device 10 according to the modification includes a waveguide filter 1F (an example of a filter section) including resonance regions 21, 22, 31, and 32, and also includes a waveguide 7 independent of the waveguide filter 1F. ing.

The waveguide filter 1F has the same configuration as the waveguide filter 1 of the embodiment described above, except that it does not include a coupling window 45 that directly couples the resonance regions 21 and 32. A first propagation path P1 is formed in the waveguide filter 1F.

The waveguide 7 directly couples the input waveguide line 82 and the output waveguide line 83, and is provided as a second propagation path P2. The waveguide 7 propagates only harmonics among the fundamental wave and harmonics supplied from the input waveguide line 82.

According to this, the harmonics adjusted to have opposite phases propagating through the first propagation path P1 and the harmonics propagating through the second propagation path P2 are combined in the output waveguide line 83. This suppresses harmonics.

The waveguide 7 is suitable as the second propagation path P2 because it can easily be made into a line that propagates only harmonics by adjusting the width. The present invention is not limited to this, and the second propagation path P2 may be composed of, for example, a microstrip line.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made by those skilled in the art.

In the above embodiment, the waveguide filter 1 is used as an example of the filter device, but the filter device is not limited to this, and the filter device may be, for example, a filter configured with a microstrip line or the like.

Hereinafter, typical embodiments of the present invention will be listed.

(1)
comprising a resonator with an adjustment section that propagates a fundamental wave and a harmonic of the fundamental wave and is provided with an adjustment section that adjusts the phase of the harmonic to an opposite phase;
a first propagation path passing through the resonator with adjustment section;
a second propagation path that does not go through the resonator with adjustment section;
is formed,
The harmonics adjusted to have opposite phases propagating through the first propagation path and the harmonics propagating through the second propagation path are combined;
filter device.

(2)
an upstream resonator disposed upstream of the resonator with an adjustment section;
a downstream resonator disposed downstream of the resonator with adjustment section;
Furthermore,
The second propagation path includes a coupling path that couples the upstream resonator and the downstream resonator.
The filter device according to (1).

(3)
The resonator with an adjustment section, the upstream resonator, and the downstream resonator are waveguide resonators that resonate the fundamental wave in a TE mode.
The filter device according to (2).

(4)
comprising two resonators with adjustment parts separated by a partition wall serving as an E plane,
A coupling window formed in the partition wall propagates a part of the harmonics tuned to the opposite phase.
The filter device according to (3).

(5)
The upstream resonator and the downstream resonator are separated by a partition wall serving as an E plane,
A coupling window as the coupling path formed in the partition wall propagates a part of the harmonic wave,
The filter device according to (3) or (4).

(6)
further comprising another resonator disposed upstream or downstream of the resonator with adjustment section,
The second propagation path is formed independently of the filter section including the resonator with adjustment section and the other resonator.
The filter device according to (1).

(7)
The second propagation path propagates only the harmonics among the fundamental wave and the harmonics.
The filter device according to (6).

(8)
A transmitter comprising the filter device according to any one of (1) to (7).

(9)
A radar comprising the filter device according to any one of (1) to (7).

1 waveguide filter (example of filter device), 2 block, 20 recess, 21 resonance region (example of upstream resonator), 22 resonance region (example of resonator with adjustment section), 221, 222 adjustment section, 23, 25 coupling window, 29 opposing surface, 3 block, 30 recess, 31 resonance region (example of resonator with adjustment section), 32 resonance region (example of downstream resonator), 311, 312 adjustment section, 33, 35 coupling window, 39 opposing surface, 4 partition plate, 41-45 coupling window, 82, 83 waveguide line, 91 magnetron, 92 pulse drive circuit, 93 circulator, 94 terminator, 95 circulator, 96 rotary joint, 97 antenna, 98 limiter Circuit, 99 Receiving circuit, 100 Radar

Claims (9)

comprising a resonator with an adjustment section that propagates a fundamental wave and a harmonic of the fundamental wave and is provided with an adjustment section that adjusts the phase of the harmonic to an opposite phase;
a first propagation path passing through the resonator with adjustment section;
a second propagation path that does not go through the resonator with adjustment section;
is formed,
The harmonics adjusted to have opposite phases propagating through the first propagation path and the harmonics propagating through the second propagation path are combined;
filter device. an upstream resonator disposed upstream of the resonator with an adjustment section;
a downstream resonator disposed downstream of the resonator with adjustment section;
Furthermore,
The second propagation path includes a coupling path that couples the upstream resonator and the downstream resonator.
A filter device according to claim 1. The resonator with an adjustment section, the upstream resonator, and the downstream resonator are waveguide resonators that resonate the fundamental wave in a TE mode.
A filter device according to claim 2. comprising two resonators with adjustment parts separated by a partition wall serving as an E plane,
A coupling window formed in the partition wall propagates a part of the harmonics tuned to the opposite phase.
A filter device according to claim 3. The upstream resonator and the downstream resonator are separated by a partition wall serving as an E plane,
A coupling window as the coupling path formed in the partition wall propagates a part of the harmonic wave,
A filter device according to claim 3. further comprising another resonator disposed upstream or downstream of the resonator with adjustment section,
The second propagation path is formed independently of the filter section including the resonator with adjustment section and the other resonator.
A filter device according to claim 1. The second propagation path propagates only the harmonics among the fundamental wave and the harmonics.
A filter device according to claim 6. A transmitter comprising a filter device according to claim 1. A radar comprising a filter device according to claim 1.

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