Filtering device, transmitter, and radar

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

Technical Field

[0001] The present invention relates to a filter device, a transmitter, and a radar.

Background Art

[0002] Generally, in a filter device, not only the fundamental wave but also its harmonics resonate. Therefore, in order to suppress the harmonics, a low-pass filter that attenuates components with a frequency higher than the fundamental wave is often used in combination (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the method of using a low-pass filter in combination has problems such as an increase in loss due to a longer path and an increase in the size of the device.

[0005] The present invention has been made in view of the above problems, and its main object is to provide a filter device capable of suppressing harmonics, a transmitter, and a radar including the same.

Means for Solving the Problems

[0006] To solve the above problems, a filter device according to one aspect of the present invention includes a resonator with an adjustment unit provided therein that propagates a fundamental wave and harmonics of the fundamental wave and adjusts the phase of the harmonics to the opposite phase. 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 are formed, and the harmonics adjusted to the opposite phase propagating through the first propagation path and the harmonics propagating through the second propagation path are combined. According to this, it becomes possible to suppress harmonics.

[0007] In the above embodiment, the second propagation path may further include an upstream resonator positioned upstream of the resonator with adjustment and a downstream resonator positioned downstream of the resonator with adjustment, and the second propagation path may include a coupling path that connects the upstream resonator and the downstream resonator. This makes it possible to obtain a steep transmission characteristic for the fundamental wave through skip coupling between the resonators while suppressing harmonics.

[0008] In the above embodiment, the resonator with adjustment section, the upstream resonator, and the downstream resonator may be waveguide-type resonators that resonate the fundamental wave in TE mode. This makes it possible to suppress harmonics while obtaining a steep transmission characteristic for the fundamental wave in a waveguide-type resonator.

[0009] In the above embodiment, the device comprises two resonators with adjustment sections separated by a partition wall that forms the E-plane, and a coupling window formed in the partition wall may propagate a portion of the out-of-phase harmonics. This makes it possible to adjust the amount of out-of-phase harmonics propagating in the first propagation path.

[0010] In the above embodiment, the upstream resonator and the downstream resonator are separated by a partition wall that forms the E-plane, and the coupling window formed in the partition wall as a coupling path may propagate a portion of the harmonics. This makes it possible to adjust the amount of harmonic propagation in the second propagation path.

[0011] In the above embodiment, the second propagation path may further include other resonators positioned upstream or downstream of the resonator with adjustment, and the second propagation path may be formed independently of the filter section including the resonator with adjustment and the other resonators. This makes it possible to suppress harmonics by the second propagation path independent of the filter section.

[0012] In the above embodiment, the second propagation path may propagate only the harmonics among the fundamental wave and the harmonics. This makes it possible to suppress the harmonics by propagating only the harmonics.

[0013] Also, the transmitter of another aspect of the present invention includes the above filter device. According to this, it becomes possible to include a filter device that realizes harmonic suppression.

[0014] Also, the radar of another aspect of the present invention includes the above filter device. According to this, it becomes possible to include a filter device that realizes harmonic suppression.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram showing a configuration example of a radar. [Figure 2] It is a diagram showing a configuration example of a filter device. [Figure 3] It is a diagram showing a configuration example of a filter device. [Figure 4] It is a diagram showing a configuration example of a filter device. [Figure 5] It is a diagram showing a configuration example of a filter device. [Figure 6] It is a diagram showing a configuration example of a filter device. [Figure 7] It is a diagram showing a configuration example of a filter device. [Figure 8] It is a diagram showing a configuration example of a filter device. [Figure 9] It is a diagram showing a reference example of a filter device.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] 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 an 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.

[0018] 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 reception circuit 99.

[0019] The magnetron 91 is a microwave generator that oscillates with a microwave of, for example, 9.4 GHz as the fundamental wave. The pulse drive circuit 92 intermittently drives the magnetron 91 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.

[0020] The waveguide filter 1 is interposed between the magnetron 91 and the antenna 97. In the present embodiment, the waveguide filter 1 is configured as a band-pass filter that allows the passage of the fundamental wave and suppresses the passage of harmonics with respect to the fundamental wave. The suppressed harmonics are consumed by the terminator 94 connected to the circulator 93.

[0021] The circulator 95 outputs the transmission signal from the waveguide filter 1 to the antenna 97 and outputs the reception signal from the antenna 97 to the reception 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.

[0022] The antenna 97 transmits the transmission signal as a radio wave pulse while rotating by a motor (not shown), and converts the received reflected wave into a reception signal. The limiter circuit 98 suppresses a high-level reception signal immediately after the start of reception. The reception circuit 99 acquires the reception signal from the antenna 97.

[0023] The path from the magnetron 91 to the antenna 97 is composed of a waveguide. Also, the path from the antenna 97 to the limiter circuit 98 is composed of a waveguide.

[0024] In this embodiment, the radar 100 to which the waveguide filter 1 is applied is a marine radar that transmits and receives microwaves, but it is not limited to this, and may be, for example, an in-vehicle radar for obstacle detection or collision avoidance that transmits and receives millimeter waves.

[0025] Figure 2 is an exploded perspective view showing an example configuration of waveguide filter 1. Waveguide filter 1 comprises two blocks 2 and 3 and a partition plate 4 sandwiched between them.

[0026] Figure 3 shows an example configuration of block 2, and is a view of block 2 from the partition plate 4 side. Figure 4 shows an example configuration of block 3, and is a view of block 3 from the partition plate 4 side.

[0027] Figure 5 shows an example of the configuration of the partition plate 4, and is a view of the partition plate 4 from the block 3 side. Figure 6 is a cross-section of block 2 when it is cut along the line VI-VI shown in Figure 3.

[0028] In the diagram, the Z direction represents the thickness direction or stacking direction of blocks 2, 3 and partition plate 4. The X and Y directions represent the short and long directions of blocks 2, 3 and partition plate 4 in a plane perpendicular to the Z direction, respectively.

[0029] Blocks 2 and 3 and partition plate 4 are made of metal. Specifically, blocks 2 and 3 are made of a conductive metal material such as aluminum. Partition plate 4 is also made of a conductive metal material such as an aluminum alloy.

[0030] Blocks 2 and 3 are separated by a partition plate 4, with the opposing surface 29 of block 2 in contact with one main surface of the partition plate 4, and the opposing surface 39 of block 3 in contact with the other main surface of the partition plate 4. Blocks 2 and 3 and the partition plate 4 are fastened together by fastening members such as screws (not shown).

[0031] As shown in Figure 3, a recess 20 for radio wave propagation is formed on the opposing surface 29 of block 2. The recess 20 includes two resonant regions 21 and 22 aligned in the Y direction, and a coupling window 23 interposed between them. The resonant region 22 has adjustment sections 221 and 222 for adjusting harmonics.

[0032] A coupling window 25 is formed at the bottom of the resonant region 21 of block 2, connecting the resonant region 21 to the outside. An input waveguide line 82 (see Figure 2) is connected to the coupling window 25, and radio waves are input from the waveguide line 82 to the resonant region 21 through the coupling window 25.

[0033] As shown in Figure 4, a recess 30 for radio wave propagation is formed on the opposing surface 39 of block 3. The recess 30 includes two resonant regions 31 and 32 aligned in the Y direction, and a coupling window 33 interposed between them. The resonant region 31 has adjustment sections 311 and 312 for adjusting harmonics.

[0034] A coupling window 35 is formed at the bottom of the resonant region 32 of block 3, connecting the resonant region 32 to the outside. An output waveguide line 83 (see Figure 2) is connected to the coupling window 35, and radio waves are output from the resonant region 32 through the coupling window 35 to the waveguide line 83.

[0035] As shown in Figure 5, the partition plate 4 has multiple connecting windows 41-45 formed therein. The partition plate 4 is sandwiched between blocks 2 and 3 and interposed between recesses 20 and 30. That is, the partition plate 4 covers both recesses 20 and 30. In this embodiment, recesses 20 and 30 are mirror-symmetrical.

[0036] The coupling windows 41-44 connect the resonant region 22 of block 2 with the resonant region 31 of block 3. The coupling window 45 connects the resonant region 21 of block 2 with the resonant region 32 of block 3.

[0037] When blocks 2, 3 and partition plate 4 are assembled and fastened, each resonant region 21, 22, 31, and 32 functions as a waveguide resonator. In this embodiment, the waveguide filter 1 includes a total of four waveguide resonators. Each resonant region 21, 22, 31, and 32 has predetermined dimensions determined based on the frequency of the radio waves (electromagnetic waves) used.

[0038] Each of the resonant regions 21, 22, 31, and 32 has a flattened shape in which the dimension in the Z direction is shorter than the dimensions in the X and Y directions, causing the radio waves to resonate in TE mode. The electric field vector of the resonant radio waves points in the Z direction. The dimension in the X direction (direction of radio wave propagation) of each of the resonant regions 21, 22, 31, and 32 is, for example, about half the wavelength of the fundamental wave.

[0039] Figure 7 is a schematic diagram showing an example of the configuration of the waveguide filter 1. As shown in the figure, the waveguide filter 1 has a first propagation path P1 that passes through resonant regions 22 and 31, which are provided with adjustment sections 221, 222, 311, and 312, and a second propagation path P2 that does not pass through the resonant regions 22 and 31.

[0040] Resonant 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 and 31, is an example of a downstream resonator.

[0041] The resonant regions 22 and 31 are separated by partition plate 4, and the resonant regions 22 and 31 are also separated by partition plate 4 (see Figure 2). Partition plate 4 is an example of a partition wall and is the E-plane of the resonant regions 21, 22, 31, and 32. The E-plane is the plane perpendicular to the electric field vector (Z direction) of the resonant fundamental wave.

[0042] The first propagation path P1 is a path that passes through resonant regions 21, 22, 31, and 32 in order. Specifically, in the first propagation path P1, the radio waves propagate in the following order: coupling window 25, resonant region 21, coupling window 23, resonant region 22, coupling windows 41-44, resonant region 31, coupling window 33, resonant region 32, and coupling window 35.

[0043] The second propagation path P2 is a path that passes through resonant regions 21 and 32 in order, but does not pass through resonant regions 22 and 31. Specifically, in the second propagation path P2, the radio waves propagate in the order of coupling window 25, resonant region 21, coupling window 45, resonant region 32, and coupling window 35. Coupling window 45 is an example of a coupling path.

[0044] The fundamental wave and its harmonics (multipliers) propagate through the first propagation path P1 and the second propagation path P2. In the first propagation path P1, the phase of the harmonics is adjusted to be out of phase by adjustment units 221, 222, 311, and 312 provided in the resonant regions 22 and 31.

[0045] Therefore, the harmonics propagating through the first propagation path P1, which are adjusted to be in opposite phase, and the harmonics propagating through the second propagation path P2 are combined in the resonant region 32, thereby suppressing the passage of harmonics. In other words, the waveguide filter 1 becomes a band-pass filter that allows the passage of the fundamental wave while suppressing the passage of harmonics.

[0046] The adjustment sections 221, 222, 311, and 312, located in the resonance regions 22 and 31 of the first propagation path P1, are spaces into which the fundamental wave cannot penetrate but harmonics can (see Figures 3 and 4). This allows for adjustment of the phase of the harmonics while leaving the fundamental wave unchanged.

[0047] The width (length in the X direction) of the adjustment sections 221, 222, 311, and 312 is preferably, for example, less than or equal to half the wavelength of the fundamental wave and more than or equal to half the wavelength of the harmonics (second harmonic).

[0048] Furthermore, the depth (length in the Y direction) of the adjustment sections 221, 222, 311, and 312 is a factor that determines the amount of phase shift of the harmonics, and is therefore adjusted so that the phase of the harmonics becomes inverse phase. Preferably, the depth of the shaping sections 221, 222, 311, and 312 is adjusted to a range of 1 / 5 to 1 / 3 of the wavelength of the harmonics (second harmonic), for example.

[0049] The coupling windows 41-44 formed between the resonant regions 22 and 31 propagate a portion of the harmonics that are tuned to be out of phase. In other words, the coupling windows 41-44 adjust the amount of coupling between the harmonic modes of resonant region 22 and the harmonic modes of resonant region 31.

[0050] Coupling windows 41 and 42 are formed at positions where harmonic modes are mainly electrically coupled, while coupling windows 43 and 44 are formed at positions where harmonic modes are mainly magnetically coupled. By adjusting the positions of coupling windows 41-44 to create a difference between the amount of electric field coupling and the amount of magnetic field coupling, the amount of harmonic propagation can be adjusted.

[0051] In the second propagation path P2, the resonant regions 21 and 32 are directly coupled by the coupling window 45, thereby improving the filter characteristics. In this embodiment, an elliptic function filter is configured using skip coupling between resonators. By coupling the input and output, the elliptic function filter exhibits a steep pass-through characteristic called a pole.

[0052] The coupling window 45 formed between the resonant regions 21 and 32 allows some of the harmonics to propagate. The coupling window 45 is formed at the center of the E-plane of the resonant regions 21 and 32. In other words, the center of the E-plane lies inside the coupling window 45.

[0053] In other words, the center of the E-plane is where the electric field of the fundamental wave is concentrated, but the electric field of the harmonics is not concentrated to a great extent. Therefore, by forming a coupling window 45 in the center of the E-plane, almost all of the fundamental wave propagates while only a portion of the harmonics propagates.

[0054] The coupling windows 41-44 formed between the resonant regions 22 and 31, and the coupling window 45 formed between the resonant regions 21 and 32, are positioned and sized such that the amount of harmonic propagation in the first propagation path P1, which is tuned to the opposite phase, is approximately equal to the amount of harmonic propagation in the second propagation path P2.

[0055] According to the embodiments described above, by forming a first propagation path P1 in the waveguide filter 1 that passes through resonant regions 22 and 31, which are provided with adjustment units 221, 222, 311, and 312 for adjusting the phase of harmonics to be inverse phase, and a second propagation path P2 that does not pass through the resonant regions 22 and 31, it becomes possible to suppress harmonics while allowing the passage of the fundamental wave.

[0056] Furthermore, in the second transmission path P2, the resonant regions 21 and 32 are directly coupled by the coupling window 45, thereby constructing an elliptic function filter utilizing the skip coupling between resonators, making it possible to obtain a steep transmission characteristic for the fundamental wave.

[0057] As shown in the example in Figure 9, there is also a method to suppress all harmonics by not coupling the harmonic modes of the resonant region 22 and the resonant region 31 using coupling windows 41-44. However, in this case, coupling the resonant regions 21 and 32 would allow the harmonics to pass through, so coupling them is not possible.

[0058] In contrast, in the embodiment shown in Figure 7, instead of suppressing all harmonics in the first propagation path P1, the phase of the harmonics is adjusted to be inverse phase. This allows the resonance regions 21 and 32 to be coupled to form a second propagation path P2, making it possible to obtain a steep transmission characteristic for the fundamental wave while suppressing the passage of harmonics.

[0059] Next, a modified example shown in Figure 8 will be described. Components that overlap with the above embodiment may be given the same number, and detailed explanations may be omitted. The filter device 10 according to the modified example includes a waveguide filter 1F (example of filter section) that includes resonance regions 21, 22, 31, and 32, and also includes a waveguide 7 independent of the waveguide filter 1F.

[0060] Waveguide filter 1F has the same configuration as waveguide filter 1 in the above embodiment, except that it does not have a coupling window 45 that directly couples the resonant regions 21 and 32. A first propagation path P1 is formed in waveguide filter 1F.

[0061] Waveguide 7 directly connects the input waveguide line 82 and the output waveguide line 83, and is provided as a second propagation path P2. Waveguide 7 propagates only the harmonics of the fundamental wave and harmonics supplied from the input waveguide line 82.

[0062] According to this, the harmonics propagating through the first propagation path P1, which are adjusted to be in opposite phase, and the harmonics propagating through the second propagation path P2 are combined in the output waveguide line 83, thereby suppressing the harmonics.

[0063] Waveguide 7 is suitable as the second propagation path P2 because its width can be easily adjusted to create a line that propagates only harmonics. However, the second propagation path P2 may be composed of, for example, a microstrip line.

[0064] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are of course possible for those skilled in the art.

[0065] In the above embodiment, a waveguide filter 1 was given as an example of a filter device, but the filter device is not limited to this, and may be a filter composed of, for example, a microstrip line.

[0066] The following lists representative embodiments of the present invention.

[0067] (1) The device includes a resonator with an adjustment section that propagates a fundamental wave and its harmonics, and adjusts the phase of the harmonics to be out of phase. The first propagation path passing through the resonator with adjustment unit, A second propagation path that does not pass through the resonator with adjustment section, Formed, The harmonic that propagates along the first propagation path and the harmonic that propagates along the second propagation path are combined. Filter device.

[0068] (2) An upstream resonator positioned upstream of the aforementioned resonator with adjustment section, A downstream resonator positioned downstream of the aforementioned resonator with adjustment section, Furthermore, The second propagation path includes a coupling path that connects the upstream resonator and the downstream resonator. (1) The filter device described above.

[0069] (3) The resonator with adjustment section, the upstream resonator, and the downstream resonator are waveguide-type resonators that resonate the fundamental wave in TE mode. (2) The filter device described above.

[0070] (4) It comprises two resonators with adjustment sections separated by a partition wall that forms the E plane, The coupling window formed in the partition wall allows a portion of the harmonics adjusted to the opposite phase to propagate. (3) The filter device described above.

[0071] (5) The upstream resonator and the downstream resonator are separated by a partition wall that forms the E plane. The coupling window formed in the partition wall as a coupling path propagates a portion of the harmonics. (3) or (4) the filter device described above.

[0072] (6) The resonator further comprises another resonator positioned upstream or downstream of the aforementioned resonator with adjustment section, The second propagation path is formed independently of the filter section, which includes the resonator with adjustment and the other resonators. (1) The filter device described above.

[0073] (7) The second propagation path propagates only the harmonics among the fundamental wave and the harmonics. (6) The filter device described above.

[0074] (8) A transmitter equipped with a filter device as described in any of (1) through (7).

[0075] (9) A radar equipped with a filter device as described in any of (1) to (7). [Explanation of Symbols]

[0076] 1 Waveguide filter (example of filter device), 2 Block, 20 Recess, 21 Resonant region (example of upstream resonator), 22 Resonant region (example of resonator with adjustment section), 221, 222 Adjustment section, 23, 25 Coupling window, 29 Opposing surface, 3 Block, 30 Recess, 31 Resonant region (example of resonator with adjustment section), 32 Resonant 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 type 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

1. The device includes a resonator with an adjustment section that propagates a fundamental wave and its harmonics, and adjusts the phase of the harmonics to be out of phase. The first propagation path passing through the resonator with adjustment section, A second propagation path that does not pass through the resonator with the adjustment unit, Formed, The harmonic that propagates along the first propagation path and the harmonic that propagates along the second propagation path are combined. Filter device.

2. An upstream resonator positioned upstream of the aforementioned resonator with adjustment section, A downstream resonator positioned downstream of the aforementioned resonator with adjustment section, Furthermore, The second propagation path includes a coupling path that connects the upstream resonator and the downstream resonator. The filter device according to claim 1.

3. The resonator with adjustment section, the upstream resonator, and the downstream resonator are waveguide-type resonators that resonate the fundamental wave in TE mode. The filter device according to claim 2.

4. A resonator comprising two resonators with adjustment sections, separated by a partition wall that forms an H-plane, The coupling window formed in the partition wall allows a portion of the harmonics adjusted to the opposite phase to propagate. The filter device according to claim 3.

5. The upstream resonator and the downstream resonator are separated by a partition wall that forms an H plane. The coupling window formed in the partition wall as a coupling path propagates a portion of the harmonics. The filter device according to claim 3.

6. The resonator further comprises another resonator positioned upstream or downstream of the aforementioned resonator with adjustment section, The second propagation path is formed independently of the filter section, which includes the resonator with adjustment and the other resonators. The filter device according to claim 1.

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

8. A transmitter comprising the filter device described in claim 1.

9. A radar comprising the filter device described in claim 1.

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