A reflectionless bandpass filter and filtering device

Abstract

The present invention discloses a non-reflection bandpass filter and filtering device. The non-reflection bandpass filter includes an input waveguide with at least one pair of metal branches on both sides; wherein the at least one pair of metal branches are symmetrically distributed about the center line of the input waveguide, and each metal branch is provided with a PCB board at the end away from the input waveguide for absorbing electromagnetic energy during electromagnetic wave transmission; an output waveguide is provided at one end of the input waveguide along the center line of the input waveguide and forms a preset gap with the input waveguide for electromagnetic wave output; a bandpass filter component is provided in the preset gap and is respectively connected to the input waveguide and the output waveguide to block the passage of electromagnetic waves except for specific frequency bands. The filter can absorb electromagnetic wave energy through the metal branches and PCB board provided on the input waveguide, thereby controlling out-of-band energy; and the bandpass filter component can control in-band performance, thereby better meeting the diverse needs of modern communications.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency devices, and in particular to a reflectionless bandpass filter and filtering equipment. Background Art

[0002] With the rapid development of wireless communication technology and the continued growth of radio media services, low-cost, more efficient, and higher-quality wireless communication systems require cavity filters with low out-of-band reflections. Reflectionless filters are an emerging area of ​​passive filters that absorb electromagnetic wave energy outside the stopband of bandpass filters, thereby reducing out-of-band signal reflections and improving overall system stability.

[0003] Currently, research on reflectionless filters has mostly focused on planar structures or lumped circuit components, operating at relatively low frequency bands. Reflectionless cavity filters, due to their excellent out-of-band absorption performance, low out-of-band signal suppression, and ability to reduce intermodulation signal interference, hold broad market prospects in the already-emerging 5G and upcoming 6G communications fields. Therefore, the design of a reflectionless bandpass filter with outstanding performance is urgently needed. Summary of the Invention

[0004] The present invention provides a reflectionless bandpass filter and a filtering device to improve the performance of the bandpass filter and meet the diverse needs of modern communications.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] According to a first aspect of an embodiment of the present invention, there is provided a reflectionless bandpass filter, comprising:

[0007] An input waveguide having a preset shape and provided with at least one pair of metal branches on both sides; wherein the at least one pair of metal branches are symmetrically distributed about the center line of the input waveguide, and each of the metal branches is provided with a PCB board at one end away from the input waveguide for absorbing electromagnetic energy during electromagnetic wave transmission;

[0008] an output waveguide, arranged at one end of the input waveguide along the center line of the input waveguide and forming a preset gap with the input waveguide for outputting electromagnetic waves;

[0009] The bandpass filter component is arranged in the preset gap and is connected to the input waveguide and the output waveguide respectively, so as to block the passage of electromagnetic waves except those in a specific frequency band.

[0010] Preferably, the metal branches are in a plurality of pairs, and the plurality of pairs of metal branches are spaced apart along the center line of the input waveguide, and each pair of metal branches is symmetrically distributed about the center line of the input waveguide.

[0011] Preferably, each pair of the metal branches has a preset size, and the preset sizes of any two pairs of the metal branches are different.

[0012] Preferably, each pair of the metal branches can be detachably mounted on both sides of the input waveguide, so as to increase or decrease the number of the metal branches or change the size of the metal branches.

[0013] Preferably, the size of the PCB board mounted on each pair of metal branches corresponds to the preset size of the pair of metal branches.

[0014] Preferably, the PCB board includes:

[0015] A substrate having a plurality of short-circuit through holes formed thereon, wherein the plurality of short-circuit through holes are collectively arranged to form a closed short-circuit area;

[0016] A metal bottom plate is provided at the bottom of the substrate;

[0017] Two metal patches are placed on top of the substrate and located within the short circuit area.

[0018] A chip resistor is fixed on the top of the substrate, and two pins of the chip resistor are respectively connected to the two metal patches for absorbing electromagnetic energy.

[0019] Preferably, the PCB board is detachably mounted on the end of the metal branch so as to be used for changing the resistance value of the chip resistor.

[0020] Preferably, the input waveguide and the at least one pair of metal branches are integrally formed.

[0021] Preferably, the bandpass filter component comprises:

[0022] A resonator is provided in the preset gap to block electromagnetic waves except those in a specific frequency band from passing through;

[0023] Two feeding plates are respectively connected between the resonator and the input waveguide, and between the resonator and the output waveguide for conducting electricity.

[0024] According to a second aspect of an embodiment of the present invention, a filtering device is provided, comprising the above-mentioned reflectionless bandpass filter.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The metal branches on the input waveguide, in conjunction with the PCB, can absorb electromagnetic waves, thereby controlling out-of-band energy. Furthermore, the use of bandpass filtering components can control in-band performance, thereby better meeting the diverse needs of modern communications.

[0027] 2. Simple structure, easy to produce, strong practicality, novel structure, and good absorption effect of external energy.

[0028] 3. By changing the size of the metal branches and the resistance value on the PCB board, the absorption efficiency of electromagnetic waves can be controlled to adapt to different electromagnetic wave transmission scenarios.

[0029] 4. By adjusting the number of metal branches, the absorbed electromagnetic wave energy can be adjusted, so that the out-of-band absorption range can be increased or decreased.

[0030] 5. The filter provided in the embodiment of the present invention can operate normally within the passband frequency band under the conditions that meet the requirements, and has high selectivity and good out-of-band suppression performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a reflectionless bandpass filter provided by the first embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the front structure of the PCB board in the first embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the back structure of the PCB board in the first embodiment of the present invention;

[0034] Figure 4 Schematic diagram of S-parameter response of the reflectionless bandpass filter according to the first embodiment of the present invention;

[0035] Figure 5 A schematic structural diagram of a reflectionless bandpass filter provided by a second embodiment of the present invention;

[0036] Figure 6 A schematic structural diagram of a reflectionless bandpass filter provided by a third embodiment of the present invention;

[0037] Figure 7 Schematic diagram of S-parameter response of a reflectionless bandpass filter according to a third embodiment of the present invention;

[0038] Figure 8 This is a schematic structural diagram of another reflectionless bandpass filter provided by the third embodiment of the present invention.

[0039] In the accompanying drawings, each reference numeral represents:

[0040] 1. Input waveguide; 11. Metal branch; 12. PCB board; 121. Substrate; 122. Metal bottom plate; 123. Metal patch; 124. Chip resistor; 1211. Short-circuit via; 120. Short-circuit area; 2. Output waveguide; 3. Bandpass filter component; 31. Resonator; 32. Feed plate; 10. Preset gap. DETAILED DESCRIPTION

[0041] In order to make the purposes, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0042] The embodiment of the present invention provides a non-reflective bandpass filter. Generally, in the S parameter curve of the filter in engineering applications, |S 11 | Generally, the requirement is less than -15dB, which is a normal standard. The filter provided by the embodiment of the present invention can work normally within the passband frequency band under the conditions that meet the requirements, and has high selectivity and good out-of-band suppression performance. At the same time, the reflectionless filter requires out-of-band |S 11 |It must also be lower than -10dB to ensure good out-of-band absorption performance.

[0043] The structure of the reflectionless bandpass filter according to the embodiment of the present invention is described in detail below.

[0044] First embodiment:

[0045] like Figure 1 As shown, a reflectionless bandpass filter provided by the first embodiment of the present invention includes an input waveguide 1, an output waveguide 2, and a bandpass filter component 3. A pair of metal branches 11 are formed on both sides of the input waveguide 1, and a PCB board 12 (different from an ordinary printed circuit board) is installed on each metal branch 11 to absorb electromagnetic energy during the transmission of electromagnetic waves. The output waveguide 2 is spaced apart from the input waveguide 1 to output the electromagnetic part. The bandpass filter component 3 is arranged between the input waveguide 1 and the output waveguide 2 to block the passage of electromagnetic waves except for a specific frequency band.

[0046] Specifically, in the above embodiment, the input waveguide 1 is in the shape of a rectangular parallelepiped. Two metal branches 11 are respectively arranged on both sides of the input waveguide 1 and are symmetrical with each other about the center line O of the input waveguide 1. Among them, the metal branch 11 is in the shape of a rectangular parallelepiped and is integrally formed of a metal material with conductive properties. The PCB board 12 is arranged on the end face of the metal branch 11 away from the end of the input waveguide 1. The PCB board 12 is provided with a chip resistor, so that the chip resistor can be used to absorb the energy of electromagnetic waves. In this embodiment, preferably, the input waveguide 1 and the metal branch 11 are integrally formed to improve the stability of the structures of the two. It can be understood that the specific shape of the above-mentioned input waveguide 1 and the metal branch 11 is only a preferred embodiment. In other embodiments, the shapes of the two can be adaptively adjusted as needed.

[0047] Reference Figure 2 and Figure 3 As shown, the PCB board 12 includes a substrate 121, a metal base plate 122, two metal patches 123, and a chip resistor 124. The substrate 121 is preferably made of FR-4 dielectric with a thickness of 1-2 mm, preferably 1.6 mm. Multiple short-circuit holes 1211 are provided on the substrate 121 to short-circuit the top and bottom of the substrate 121; the multiple short-circuit holes 1211 collectively form a closed short-circuit area 120. The metal base plate 122 is disposed at the bottom of the substrate 121. The metal base plate 122 can be a solid metal plate or a metal layer formed by electroplating or sputtering. The two metal patches 123 are rectangular in shape and are arranged on the top of the substrate 121 and are located in the short-circuit area 120. The short-circuit area 120 formed by multiple short-circuit through-holes 1211 can short-circuit the metal base plate 122 and the two metal patches 123 to ensure that the electromagnetic waves are absorbed by the chip resistors 124 on the PCB board and are not radiated outside the device, thereby preventing electromagnetic leakage. The chip resistor 124 is fixed to the top of the substrate 121, and the two pins of the chip resistor 124 are respectively connected to the two metal patches 123 to absorb electromagnetic energy. It can be understood that, referring to Figure 1 As shown, when the PCB board 12 is mounted on the metal branch 11 , the metal base plate 122 faces outward (ie, away from the input waveguide 1 ), and the chip resistor 124 faces inward (ie, facing the input waveguide 1 ).

[0048] Reference Figure 1 As shown, the output waveguide 2 is arranged at one end of the input waveguide 1 along the center line O of the input waveguide 1 and forms a preset gap 10 with the input waveguide 1 for outputting electromagnetic waves. Accordingly, the bandpass filter component 3 is arranged in the preset gap 10 to allow electromagnetic waves of a specific frequency band to pass through and block electromagnetic waves of other frequency bands from passing through. Specifically, refer to Figure 1As shown, the bandpass filter assembly 3 includes a resonator 31 and two feed plates 32. The resonator 31 is disposed within the preset gap 10 to block electromagnetic waves except those in a specific frequency band. The two feed plates 32 are connected between the resonator 31 and the input waveguide 1, and between the resonator 31 and the output waveguide 2, respectively, for electrical conduction. The resonator 31 in this embodiment is a conventional structure used in the art and will not be described in detail here.

[0049] Reference Figure 4 As shown in the S parameter response of the reflectionless bandpass filter provided in the first embodiment of the present invention, it can be seen that the filter is a third-order bandpass filter with a passband center frequency of 11.4 GHz. 11 | is less than -20dB, and there is a transmission zero in the upper and lower stop bands, which enables the filter to achieve good in-band performance and out-of-band suppression performance. In addition, there is an absorption pole outside the band at 10.6GHz, |S 11 |Less than -20dB, and the absorption rate exceeds 90%. Therefore, the signal at this frequency will be absorbed by the chip resistor 124 and will not be reflected back to the previous stage device.

[0050] In summary, the reflectionless bandpass filter provided in the first embodiment of the present invention can absorb the energy of electromagnetic waves through the metal branches 11 provided on the input waveguide 1 in conjunction with the PCB board 12, thereby controlling the out-of-band energy; and, the bandpass filtering component 3 can control the in-band performance, thereby better meeting the diverse needs of modern communications.

[0051] Second embodiment:

[0052] like Figure 5 FIG. 1 shows a reflectionless bandpass filter provided by a second embodiment of the present invention, comprising an input waveguide 1, an output waveguide 2, and a bandpass filter assembly 3. Compared with the first embodiment, this embodiment is different in that the size of the metal branch 11 is adjustable.

[0053] Specifically, in this embodiment, the metal branch 11 is detachably mounted on the input waveguide 1 (e.g., by bolting or snap-fitting), allowing the size of the metal branch 11 to be adjusted as needed to accommodate different electromagnetic transmission scenarios. The dimensions of the metal branch 11 include at least length, thickness, and width.

[0054] In addition, in this embodiment, each PCB board 12 installed on the metal branch 11 should correspond to the size of the metal branch 11, that is, if the size of the metal branch 11 changes, the size of the PCB board 12 must also change accordingly, and when the size of the PCB board 12 changes, the chip resistor 124 installed on the PCB board 12 will also change accordingly (that is, the resistance value changes), thereby changing the energy absorption rate of electromagnetic waves to adapt to different electromagnetic transmission scenarios.

[0055] Except for the above structure, the rest of the structure of this embodiment is the same as that of the first embodiment and will not be described again here.

[0056] Third embodiment:

[0057] like Figure 6 FIG. 3 shows a reflectionless bandpass filter provided by the third embodiment of the present invention, comprising an input waveguide 1, an output waveguide 2, and a bandpass filter assembly 3. Compared with the first embodiment, this embodiment is different in that the number of metal branches 11 is adjustable.

[0058] Specifically, such as Figure 6 As shown, in this embodiment, eight pairs of metal branches 11 (six, nine, or other numbers) are provided on both sides of the input waveguide 1. The eight pairs of metal branches 11 are spaced apart along the centerline O of the input waveguide 1, and each pair of metal branches 11 is symmetrically distributed about the centerline O of the input waveguide 1. Therefore, by increasing the number of metal branches 11, the absorbed electromagnetic wave energy can be increased, thereby expanding the out-of-band absorption range.

[0059] Reference Figure 7 As shown in the S parameter response of the reflectionless bandpass filter provided in the third embodiment of the present invention, it can be seen that the filter is a third-order bandpass filter with a passband center frequency of 11.4 GHz. 11 The filter's noise level is less than -15dB, and both the upper and lower stopbands have a transmission zero, enabling the filter to achieve excellent in-band performance and out-of-band rejection. Consequently, signals in this frequency band are absorbed by the chip resistor 124 and are not reflected back to the previous device. Furthermore, compared to the first embodiment, the increased number of metal branches 11 in this embodiment significantly increases the out-of-band absorption range to 10.1 GHz to 12.5 GHz. Outside the passband, the overall absorption rate exceeds 80%.

[0060] In addition, if Figure 6As shown, the eight pairs of metal branches 11 in this embodiment all have preset sizes, and the preset sizes of any two pairs of metal branches 11 are different. Based on the second embodiment, it can be seen that when the sizes of the metal branches 11 vary, the absorption rate of electromagnetic waves varies. Therefore, the absorption rate of electromagnetic waves can be adjusted by installing metal branches 11 of different sizes. It will be understood that, similar to the second embodiment, the size of the PCB board mounted on each pair of metal branches 11 corresponds to the preset size of the pair of metal branches 11.

[0061] In a preferred embodiment, if Figure 8 As shown, each pair of metal branches 11 can be detachably mounted on both sides of the input waveguide 1. Therefore, when the absorption rate of electromagnetic waves needs to be adjusted, the number of installed metal branches 11 can be increased or decreased, or metal branches 11 of different sizes can be directly replaced.

[0062] Except for the above structure, the rest of the structure of this embodiment is the same as that of the first embodiment and will not be described again here.

[0063] Fourth embodiment:

[0064] On the basis of the above-mentioned first to third embodiments, the fourth embodiment of the present invention further provides a filtering device, which includes the reflectionless bandpass filter described in any one of the above-mentioned first to third embodiments.

[0065] In summary, the embodiment of the present invention provides a reflectionless bandpass filter and filtering device, which have the following beneficial effects:

[0066] 1. The metal branches 11 provided on the input waveguide 1 cooperate with the PCB board 12 to absorb the energy of electromagnetic waves, thereby controlling the out-of-band energy; and the bandpass filter component 3 can control the in-band performance, thereby better meeting the diverse needs of modern communications.

[0067] 2. Simple structure, easy to produce, strong practicality, novel structure, and good absorption effect of external energy.

[0068] 3. By changing the size of the metal branches 11 and the resistance value of the resistors on the PCB board 12, the absorption efficiency of electromagnetic waves can be controlled to adapt to different electromagnetic wave transmission scenarios.

[0069] 4. By adjusting the number of metal branches 11, the absorbed electromagnetic wave energy can be adjusted, so that the out-of-band absorption range is increased or decreased.

[0070] 5. The filter provided in the embodiment of the present invention can operate normally within the passband frequency band under the conditions that meet the requirements, and has high selectivity and good out-of-band suppression performance.

[0071] In the description of this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and integrate different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless otherwise inconsistent.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A reflectionless bandpass filter, characterized in that: include: An input waveguide having a preset shape and provided with at least one pair of metal branches on both sides; wherein the at least one pair of metal branches are symmetrically distributed about the center line of the input waveguide, and each of the metal branches is provided with a PCB board at one end away from the input waveguide for absorbing electromagnetic energy during electromagnetic wave transmission; an output waveguide, arranged at one end of the input waveguide along the center line of the input waveguide and forming a preset gap with the input waveguide for outputting electromagnetic waves; The bandpass filter component is arranged in the preset gap and is respectively connected to the input waveguide and the output waveguide to block the passage of electromagnetic waves except those in a specific frequency band.

2. The reflectionless bandpass filter according to claim 1, wherein: There are multiple pairs of metal branches, which are spaced apart along the center line of the input waveguide, and each pair of metal branches is symmetrically distributed about the center line of the input waveguide.

3. The reflectionless bandpass filter according to claim 2, wherein: Each pair of the metal branches has a preset size, and the preset sizes of any two pairs of the metal branches are different.

4. The reflectionless bandpass filter according to claim 3, wherein: Each pair of the metal branches can be detachably mounted on both sides of the input waveguide, so as to increase or decrease the number of the metal branches or change the size of the metal branches.

5. The reflectionless bandpass filter according to claim 3, wherein: The size of the PCB board mounted on each pair of metal branches corresponds to the preset size of the pair of metal branches.

6. The reflectionless bandpass filter according to claim 5, characterized in that The PCB board includes: A substrate having a plurality of short-circuit through holes formed thereon, wherein the plurality of short-circuit through holes are collectively arranged to form a closed short-circuit area; A metal bottom plate is provided at the bottom of the substrate; Two metal patches are placed on top of the substrate and located within the short circuit area. A chip resistor is fixed on the top of the substrate, and two pins of the chip resistor are respectively connected to the two metal patches for absorbing electromagnetic energy.

7. The reflectionless bandpass filter according to claim 6, wherein: The PCB board is detachably mounted on the end of the metal branch to be used for changing the resistance value of the chip resistor.

8. The reflectionless bandpass filter according to claim 1, wherein: The input waveguide and the at least one pair of metal branches are integrally formed.

9. The reflectionless bandpass filter according to claim 1, wherein The bandpass filtering component comprises: A resonator is provided in the preset gap to block electromagnetic waves except those in a specific frequency band from passing through; Two feeding plates are respectively connected between the resonator and the input waveguide, and between the resonator and the output waveguide for conducting electricity.

10. A filtering device, characterized in that: Comprising a reflectionless bandpass filter as claimed in any one of claims 1 to 9.

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