CN108847516B - Lost foam waveguide high-pass filter - Google Patents
Lost foam waveguide high-pass filter Download PDFInfo
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- CN108847516B CN108847516B CN201810866247.XA CN201810866247A CN108847516B CN 108847516 B CN108847516 B CN 108847516B CN 201810866247 A CN201810866247 A CN 201810866247A CN 108847516 B CN108847516 B CN 108847516B
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- waveguide
- pass filter
- resonant cavity
- evanescent
- resonant
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- 239000006260 foam Substances 0.000 title claims abstract description 10
- 230000008878 coupling Effects 0.000 claims abstract description 36
- 238000010168 coupling process Methods 0.000 claims abstract description 36
- 238000005859 coupling reaction Methods 0.000 claims abstract description 36
- 230000005540 biological transmission Effects 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims description 7
- 230000008054 signal transmission Effects 0.000 claims description 6
- 238000000465 moulding Methods 0.000 claims description 2
- 238000003780 insertion Methods 0.000 abstract description 5
- 230000037431 insertion Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 230000001629 suppression Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
Abstract
The invention discloses a lost foam waveguide high-pass filter. The vanishing mode waveguide high-pass filter comprises a vanishing mode waveguide and two coupling waveguides which are respectively connected with two ends of the vanishing mode waveguide and serve as input and output ports; a resonant cavity for providing an out-of-band transmission zero is coupled to at least one coupling waveguide, the resonant frequency of the resonant cavity being within the stop band of the evanescent waveguide high pass filter. Compared with the prior art, the invention has the advantages that the simple resonant cavity structure is arranged on the input port and/or the output port of the evanescent mode waveguide high-pass filter, the zero effect of the resonant cavity is used for realizing the transmission zero of the high-pass filter without increasing the waveguide length and meeting the requirement of compact structure, the out-of-band suppression is increased, and the insertion loss of the high-pass filter is reduced. In addition, the technical scheme of the invention has simple structure, easy realization and good application prospect.
Description
Technical Field
The invention relates to a waveguide filter, in particular to a lost-foam waveguide high-pass filter.
Background
The high-pass filter is a filter with a low-end cut-off and high-end passing mode of frequency response, and is widely applied to various communication or radar systems. In the microwave or millimeter wave frequency band with higher frequency, the waveguide type high-pass filter is widely applied to the front end of an electronic system with low local oscillation and is used for filtering the reverse radiation of the local oscillation signal and inhibiting the mirror frequency signal.
The common waveguide high-pass filter mainly comprises a broadband band-pass filter and a vanishing mode high-pass filter. If the ultra-wideband waveguide band-pass filter has no zero point, the out-of-band rejection is not good enough; if a band zero design is used, the wideband bandpass filter is susceptible to in-band resonance due to higher-order modes, where the performance of the system can be severely degraded. In addition, the waveguide broadband band-pass filter has higher requirements on processing size, and thus, the cost is relatively higher. The vanishing mode waveguide high-pass filter adopts a section of rectangular waveguide (vanishing mode waveguide) with smaller broadside, the broadside length of the rectangular waveguide is smaller than 1/2 of the wavelength of the frequency to be suppressed, the cut-off frequency of the rectangular waveguide is higher than the frequency to be suppressed, and the function of the high-pass filter is realized. The high-pass filter of the form is easier to process and has little insertion loss because of no window partition wall. However, the high-pass filter of the form has no out-of-band transmission zero point, the order of the filter is determined by the length of the waveguide, and the increase of the out-of-band rejection can only be realized by increasing the length of the waveguide, which is unfavorable for the miniaturization of the high-pass filter.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a lost foam waveguide high-pass filter with a transmission zero, which can increase out-of-band rejection through the transmission zero under the condition of not increasing the length of a waveguide.
The technical scheme adopted by the invention specifically solves the technical problems as follows:
a high-pass filter of vanishing mode waveguide comprises vanishing mode waveguide and two coupling waveguides as input and output ports connected with two ends of vanishing mode waveguide respectively; a resonant cavity for providing an out-of-band transmission zero is coupled to at least one coupling waveguide, the resonant frequency of the resonant cavity being within the stop band of the evanescent waveguide high pass filter.
Preferably, one of the resonant cavities is connected to each of the two coupling waveguides, and the resonant frequencies of the two resonant cavities are different. So that a plurality of transmission zeros can be added to the filter.
Preferably, the resonant cavity is connected to a side surface of the coupling waveguide to which it is connected, and is disposed perpendicularly with respect to a signal transmission direction of the coupling waveguide to which it is connected. Or the resonant cavity is connected to the end surface of the coupling waveguide connected with the resonant cavity, which is connected with the evanescent mode waveguide, and is arranged in parallel relative to the signal transmission direction of the coupling waveguide connected with the resonant cavity.
In order to facilitate the adjustment of the transmission zero point position, further, a tuning component for adjusting the resonance frequency of the resonant cavity is arranged on the resonant cavity.
Preferably, the tuning component is a tuning screw insertable into the resonant cavity.
Further preferably, the tuning screw is disposed at a central position of the resonant cavity.
Preferably, the evanescent mode waveguide high pass filter is manufactured in a monolithic process.
Preferably, the evanescent mode waveguide is connected with the coupling waveguide through a step-shaped matching structure.
Preferably, the evanescent mode waveguide high-pass filter further comprises a waveguide turning structure.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
according to the invention, the resonant cavity is additionally arranged on the port of the evanescent mode waveguide high-pass filter, so that the zero effect of the resonant cavity is used for realizing the transmission zero of the high-pass filter without increasing the length of the waveguide, the out-of-band suppression is increased, and the insertion loss of the high-pass filter is reduced.
Drawings
FIG. 1 is a schematic diagram of a first embodiment of a evanescent mode waveguide high-pass filter according to the present invention; the drawings include: 1. coupling waveguide, 2, coupling waveguide, 3, resonant cavity, 4, matching structure, 5, matching structure, 6, waveguide turning structure, 7, vanishing mode waveguide;
FIG. 2 is a side view of the evanescent mode waveguide high pass filter of FIG. 1;
FIG. 3 is an equivalent circuit diagram of the evanescent mode waveguide high pass filter of FIG. 1;
FIG. 4 is a perspective view of the structure of the cavity portion of the evanescent mode waveguide high-pass filter of FIG. 1;
FIG. 5 is a frequency response curve of the evanescent mode waveguide high pass filter of FIG. 1;
FIG. 6 is a schematic diagram of a second embodiment of a evanescent mode waveguide high-pass filter according to the present invention;
fig. 7 is a schematic structural diagram of a third embodiment of the evanescent mode waveguide high-pass filter of the present invention.
Detailed Description
Aiming at the defects of the prior art, the invention aims to realize the transmission zero point of the high-pass filter by using the zero point effect of the resonant cavity under the condition of not increasing the length of the waveguide by additionally arranging the resonant cavity on the port of the high-pass filter of the evanescent mode waveguide, increase out-of-band inhibition and reduce the insertion loss of the high-pass filter.
Specifically, the vanishing mode waveguide high-pass filter comprises a vanishing mode waveguide and two coupling waveguides which are respectively connected with two ends of the vanishing mode waveguide and serve as input and output ports; a resonant cavity for providing an out-of-band transmission zero is coupled to at least one coupling waveguide, the resonant frequency of the resonant cavity being within the stop band of the evanescent waveguide high pass filter.
Generally, only one transmission zero point is set for the filter, but more than one transmission zero point may be set for the filter to more effectively increase the out-of-band rejection capability, for example, the two coupling waveguides are respectively connected with one resonant cavity, and the resonant frequencies of the two resonant cavities are different, so that a plurality of transmission zero points can be added for the filter.
The resonator may be arranged in a number of different ways, preferably the resonator is connected to the side of the coupling waveguide to which it is connected and is arranged perpendicularly with respect to the signal transmission direction of the coupling waveguide to which it is connected. Or the resonant cavity is connected to the end surface of the coupling waveguide connected with the resonant cavity, which is connected with the evanescent mode waveguide, and is arranged in parallel relative to the signal transmission direction of the coupling waveguide connected with the resonant cavity. In both of these schemes, the latter is preferred because it does not increase the dimension of the filter in the vertical direction, and the structure is more compact.
The structure of the resonant cavity determines the resonant frequency, once the conventional resonant cavity is designed and manufactured, the transmission zero position is fixed, and in order to flexibly adjust the transmission zero position, a tuning component for adjusting the resonant frequency of the resonant cavity can be further arranged on the resonant cavity. The tuning element is preferably a tuning screw insertable into the resonator, preferably centrally located in the resonator.
For the convenience of public understanding, the following detailed description of the present invention will be made with reference to several specific embodiments in conjunction with the accompanying drawings:
fig. 1 shows a basic structure of a first embodiment, where the evanescent mode waveguide high-pass filter of the present embodiment works in Ku band, and is applied to the front end of a satellite communication system, to filter image signals, and reduce interference of the system. As shown in fig. 1, the evanescent mode waveguide high-pass filter includes a coupling waveguide 1 as an input port and an output port of the filter, a coupling waveguide 2, and a evanescent mode waveguide 7 between the input port and the output port, the coupling waveguide 1 and the coupling waveguide 2 being standard rectangular waveguides BJ120; in the figure, 4 and 5 are respectively matching structures for connecting the evanescent mode waveguide 7 and the coupling waveguides 1 and 2, and the matching structures 4 and 5 in the embodiment are step-shaped matching structures so as to realize matching between a port standard waveguide and the evanescent mode waveguide inside the filter and realize better echo characteristics; the interface size of the evanescent mode waveguide 7 inside the filter is smaller, and the cut-off frequency of the evanescent mode waveguide is higher than the highest frequency of the frequency band to be suppressed; in order to meet the performance index requirements, the evanescent mode waveguide high pass filter of the present embodiment is provided with a waveguide turning structure 6 employing a conventional waveguide turning structure (it should be noted that the waveguide turning structure is not essential). As shown in fig. 1, a resonant cavity 3 parallel to the signal transmission direction of the coupling waveguide 1 is connected to the end surface where the coupling waveguide 1 and the evanescent mode waveguide 7 are connected, and the resonant frequency of the resonant cavity 3 is within the stop band range of the evanescent mode waveguide high-pass filter, and the specific resonant frequency can be set near the frequency to be suppressed according to actual needs.
Fig. 2 is a side view of the evanescent mode waveguide high pass filter of fig. 1.
Fig. 3 is an equivalent circuit diagram of the vanishing mode waveguide high-pass filter of fig. 1, and as shown in fig. 3, the resonant cavity 3 is equivalent to a resonator connected in parallel to a transmission line, and it is known from circuit theory that a frequency signal near a resonant frequency is totally reflected and cannot pass, and information with a frequency far from the resonant frequency passes completely.
Fig. 4 is a structural perspective view of the resonant cavity portion of the evanescent mode waveguide high-pass filter of fig. 1, and it can be seen that the caliber sizes of the resonant cavity 3 and the evanescent mode waveguide 7 are smaller than the caliber size of the coupling waveguide 1, so that the evanescent mode waveguide high-pass filter can be integrated on the same end face of the coupling waveguide 1 at the same time, and on one hand, the evanescent mode waveguide high-pass filter is convenient to process, and on the other hand, because the direction of the evanescent mode waveguide high-pass filter is parallel (but not perpendicular) to the coupling waveguide 1, no additional volume is occupied, and the volume of the high-pass filter is effectively reduced.
Fig. 5 is a frequency response curve of the Ku band high-pass filter. The waveguide high-pass filter has very compact structure, and the whole dimension has the length of less than 40mm and the height of less than 18mm. The performance requires a passband of 13.75 GHz-14.6 GHz, and the out-of-band DC-12.8 GHz requires an out-of-band rejection of greater than 35dB. If a conventional waveguide high-pass filter is used, this requirement cannot be fulfilled at all in such a small volume. As can be seen from fig. 5, the vanishing mode waveguide high-pass filter of the present embodiment can fully meet the above performance requirements, and the structural dimensions can also meet the requirements. The high-pass filter structurally can be formed by processing a metal part through an integral molding process, is convenient to process and produce, and is beneficial to reducing production cost.
Fig. 6 shows a second embodiment of the invention. As shown in fig. 6, in this embodiment, two resonators are connected to the input port and the output port of the high-pass filter in the vertical direction, respectively, and the high-pass filter with zero point can be realized as well. If only one resonant cavity is added at one port, or two resonant cavities with the same resonant frequency are added at two ports, a zero point can be formed; if a resonant cavity with different resonant frequencies is added to each of the two ports, two transmission zeros can be formed. The structure and working principle of the rest of the present embodiment are the same as those of the previous embodiment, and will not be repeated here. However, compared with the parallel-direction resonator of fig. 1, the vertical-direction resonator of the present embodiment occupies a larger volume and is more difficult to process, so that it is preferable to use the parallel-direction resonator.
Fig. 7 shows a third embodiment of the invention. Similar to the structure of fig. 1, in this embodiment, a resonant cavity in a parallel direction is disposed on one of the coupling waveguides serving as the input/output ports, and a tuning screw capable of being inserted into the resonant cavity is disposed at the center of the resonant cavity, and by means of the tuning screw, the resonant frequency of the resonant cavity can be adjusted, thereby realizing adjustment of the position of the transmission zero point. The tuning screw corresponds to a loading capacitor, and the deeper the tuning screw enters the resonant cavity, the lower the resonant frequency and the corresponding transmission zero point generated by the resonant cavity.
In summary, the invention can realize the transmission zero point of the high-pass filter by using the zero point effect of the resonant cavity under the conditions of not increasing the length of the waveguide and meeting the requirement of compact structure by arranging a simple resonant cavity structure on the input port and/or the output port of the evanescent mode waveguide high-pass filter, thereby increasing out-of-band inhibition and reducing the insertion loss of the high-pass filter. In addition, the technical scheme of the invention has simple structure, easy realization and good application prospect.
Claims (8)
1. A high-pass filter of vanishing mode waveguide comprises vanishing mode waveguide and two coupling waveguides as input and output ports connected with two ends of vanishing mode waveguide respectively; the lost foam waveguide high-pass filter is characterized in that the lost foam waveguide high-pass filter is manufactured by an integral molding process; a resonant cavity for providing out-of-band transmission zero is connected to at least one coupling waveguide, and the resonant frequency of the resonant cavity is within the stop band range of the evanescent mode waveguide high-pass filter; the evanescent mode waveguide is connected with the coupling waveguide through a step-shaped matching structure.
2. The evanescent waveguide high-pass filter of claim 1 wherein one of the resonant cavities is connected to each of the two coupling waveguides and the resonant frequencies of the two resonant cavities are different.
3. A evanescent waveguide high pass filter according to claim 1 wherein the resonant cavity is connected to the side of the coupling waveguide to which it is connected and is disposed perpendicularly with respect to the signal propagation direction of the coupling waveguide to which it is connected.
4. The evanescent waveguide high-pass filter according to claim 1, wherein the resonator is connected to an end surface of the coupled waveguide to which it is connected and is disposed in parallel with respect to a signal transmission direction of the coupled waveguide to which it is connected.
5. A evanescent waveguide high-pass filter according to claim 1 wherein the resonant cavity is provided with tuning means for adjusting its resonant frequency.
6. A lost foam waveguide high-pass filter according to claim 5 wherein said tuning member is a tuning screw insertable into said resonant cavity.
7. A lost foam waveguide high-pass filter according to claim 6 wherein said tuning screw is disposed in a central location of said resonant cavity.
8. A lost foam waveguide high-pass filter according to claim 1 further comprising a waveguide turn structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810866247.XA CN108847516B (en) | 2018-08-01 | 2018-08-01 | Lost foam waveguide high-pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810866247.XA CN108847516B (en) | 2018-08-01 | 2018-08-01 | Lost foam waveguide high-pass filter |
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| Publication Number | Publication Date |
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| CN108847516A CN108847516A (en) | 2018-11-20 |
| CN108847516B true CN108847516B (en) | 2024-01-19 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201810866247.XA Active CN108847516B (en) | 2018-08-01 | 2018-08-01 | Lost foam waveguide high-pass filter |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110504945B (en) * | 2019-08-05 | 2022-12-02 | 电子科技大学 | Reconfigurable annular filtering device |
| CN111326838B (en) * | 2020-02-17 | 2021-08-03 | 电子科技大学 | Miniaturized waveguide filter based on evanescent mode |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1564835A1 (en) * | 2004-02-16 | 2005-08-17 | Siemens Mobile Communications S.p.A. | Inline waveguide filter with up to two out-of-band transmission zeros |
| CN201084809Y (en) * | 2007-09-07 | 2008-07-09 | 西安达威通信设备有限公司 | A Ku wave band bypass coupling wave-guide filter |
| CN106129552A (en) * | 2016-08-30 | 2016-11-16 | 江苏贝孚德通讯科技股份有限公司 | A kind of millimeter waveguide high pass filter |
| CN208753478U (en) * | 2018-08-01 | 2019-04-16 | 江苏贝孚德通讯科技股份有限公司 | A kind of evaporative pattern waveguide high-pass filter |
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2018
- 2018-08-01 CN CN201810866247.XA patent/CN108847516B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1564835A1 (en) * | 2004-02-16 | 2005-08-17 | Siemens Mobile Communications S.p.A. | Inline waveguide filter with up to two out-of-band transmission zeros |
| CN201084809Y (en) * | 2007-09-07 | 2008-07-09 | 西安达威通信设备有限公司 | A Ku wave band bypass coupling wave-guide filter |
| CN106129552A (en) * | 2016-08-30 | 2016-11-16 | 江苏贝孚德通讯科技股份有限公司 | A kind of millimeter waveguide high pass filter |
| CN208753478U (en) * | 2018-08-01 | 2019-04-16 | 江苏贝孚德通讯科技股份有限公司 | A kind of evaporative pattern waveguide high-pass filter |
Non-Patent Citations (1)
| Title |
|---|
| 消失模波导滤波器的新结构;吴须大;空间电子技术(第4期);全文 * |
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