CN113224483A - Three-passband filter based on SLR structure - Google Patents
Three-passband filter based on SLR structure Download PDFInfo
- Publication number
- CN113224483A CN113224483A CN202110310572.XA CN202110310572A CN113224483A CN 113224483 A CN113224483 A CN 113224483A CN 202110310572 A CN202110310572 A CN 202110310572A CN 113224483 A CN113224483 A CN 113224483A
- Authority
- CN
- China
- Prior art keywords
- resonator
- circuit branch
- branch
- short
- passband
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 10
- 239000002184 metal Substances 0.000 claims description 3
- 238000003780 insertion Methods 0.000 abstract description 9
- 230000037431 insertion Effects 0.000 abstract description 9
- 230000007547 defect Effects 0.000 abstract description 5
- 230000005540 biological transmission Effects 0.000 abstract description 3
- 230000008878 coupling Effects 0.000 abstract 1
- 238000010168 coupling process Methods 0.000 abstract 1
- 238000005859 coupling reaction Methods 0.000 abstract 1
- 238000004891 communication Methods 0.000 description 11
- 238000000034 method Methods 0.000 description 7
- 238000013461 design Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000010354 integration Effects 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
Images
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
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line 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
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20309—Strip line filters with dielectric resonator
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
The invention belongs to the technical field of radio frequency transmission devices, and particularly relates to a microstrip three-passband filter. Two multi-branch asymmetrical loading resonator units and two input and output feeder lines are arranged on the front surface of the microstrip substrate. The multi-branch asymmetrical loading resonator consists of a common half-wavelength resonator, an open-circuit branch and a short-circuit branch, wherein the open-circuit branch is loaded at the symmetrical line of the half-wavelength resonator, and the short-circuit branch is loaded at the asymmetrical line of the half-wavelength resonator. After the two multi-branch asymmetrical loading resonator units are folded, the filter is formed by electric coupling. The frequencies of the first, second and third pass bands of the filter are respectively influenced by the lengths of the short-circuit branch, the half-wavelength resonator and the open-circuit branch. The invention solves the defects of difficult passband frequency adjustment and large insertion loss of the traditional three-passband filter based on the asymmetric branch loading resonator.
Description
Technical Field
The invention belongs to the technical field of radio frequency transmission devices, and particularly relates to a microstrip three-passband filter.
Background
With the rapid development of modern communication technology and internet technology, more and more wireless communication technologies are widely applied in people's work and life, such as Worldwide Interoperability for Microwave Access (WiMAX) frequency band, indoor Wireless Local Area Network (WLAN) frequency band, Bluetooth (Bluetooth) frequency band, Global Positioning System (GPS) frequency band, 4G and 5G mobile communication technology frequency band, and so on. Due to the demand of modern communication, a communication terminal often meets a plurality of communication systems at the same time, so that the requirements on equipment of a system circuit, integration, reliability and the like are higher and higher. In a wireless communication system, a filter in a radio frequency front end is an important component, and the characteristics of the filter play an important role in the whole communication transceiving system.
The filter is used for filtering system noise and interference of other channel signals to the maximum extent, and the quality of the performance of the filter directly influences the stability and performance indexes of the whole wireless communication system. How to make a high-efficiency communication system fully utilize limited spectrum resources and work in multiple protocol modes has become one of the key problems to be solved in the communication field. However, the traditional single-passband filter is only suitable for a single frequency band and cannot meet the requirements of modern communication technology. The multi-passband filter and the miniaturization of the filter are deeply researched, the integration is facilitated, the cost is low, and the like, and the method has important significance.
The filter has various types, can be realized in different modes such as a coaxial cavity, a waveguide, a medium, ceramics, a microstrip line and the like, and also comprises a surface acoustic wave filter designed by a piezoelectric substrate material and a bulk acoustic wave filter designed by utilizing a quartz crystal. The microstrip filter has the advantages of simple structure, easy processing, low cost, small size, easy integration and the like, and is widely applied to a microwave radio frequency system.
The first one is a multi-resonator method, and a plurality of resonators with different resonant frequencies are reasonably arranged to resonate at a designed frequency, so that the required multi-passband filter is obtained. The main advantages of this design method are small insertion loss, small in-band fluctuation and high out-of-band rejection, but at the expense of size, the final result is large size and inconvenient miniaturization.
The second method is a method of designing a multi-passband filter based on a multi-section Stepped Impedance Resonator (SIR). However, the filter size is large and the out-of-band rejection degree is not high due to the pure utilization of three segments of SIR, and the design of the three segments of SIR is somewhat complicated, which is not beneficial to analyzing the resonance characteristics of the filter.
A third approach to designing multi-passband filters is to use Stub Loaded Resonators (SLRs), the resonant frequency of such filters being generated by odd-even mode resonance, with the advantage that the electrical length of the loaded stub only affects the even mode resonant frequency, independently of the odd mode resonant frequency. Compared with the SIR structure, the filter designed by the method has the advantages that the resonance frequency is controllable, but the size is larger, and the high-order harmonic wave of the SLR structure is utilized to design the three-band filter, so that the filter has the defects of complicated design, difficulty in analysis and small frequency adjusting range. Three-passband filters were obtained by asymmetrically Stub-Loaded Resonators in the literature (s. -w.lan, m. -h.weng, s. -j.chang, c. -y.hung.and s. -k.lium, a Tri-Band pass Filter With Wide stop and Using Asymmetric Stub-Loaded detectors, IEEE micro.wire company.let., vol.25, No.1, pp.19-21, jan.2015), but the passband frequencies were not easily adjustable and the circuit size was large.
The three-passband filter is designed by utilizing the branch loading resonators or the asymmetric branch loading resonators, and is generated through the harmonic characteristics of the three-passband filter, so that the frequency adjustment is difficult, a certain parameter is changed independently sometimes, the three passbands are changed along with the change of the certain parameter, and in addition, the defect that the harmonic characteristic analysis is difficult is also caused.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a three-passband filter based on an SLR structure, the passband frequency of the three-passband filter is flexibly adjustable within a certain range, and the three-passband filter has low insertion loss and small volume.
In order to achieve the purpose, the technical scheme of the invention is as follows: a three-passband filter based on an SLR structure comprises a microstrip substrate, wherein a first input/output feeder line, a second input/output feeder line, a first multi-branch asymmetrical loading resonator unit and a second multi-branch asymmetrical loading resonator unit are arranged on the front side of the microstrip substrate, the first multi-branch asymmetrical loading resonator unit and the first input/output feeder line are distributed in a central symmetrical mode relative to the second multi-branch asymmetrical loading resonator unit and the second input/output feeder line, and the second multi-branch asymmetrical loading resonator unit and the first multi-branch asymmetrical loading resonator unit are the same in structure, and the three-passband filter is characterized in that: the first asymmetrically loaded resonator unit 7 includes a first half-wavelength resonator, a first open-circuit stub loaded on the symmetric line of the first half-wavelength resonator, and a first short-circuit stub loaded on the asymmetric line of the first half-wavelength resonator.
The three-passband filter based on the SLR structure is characterized in that: the first multi-branch asymmetric loading resonator unit is folded into a C shape, the tail ends of the two ends of the first multi-branch asymmetric loading resonator unit are folded into an S shape, and the first open-circuit branch is folded into an L shape.
The three-passband filter based on the SLR structure is characterized in that: the first open-circuit branch and the first short-circuit branch are loaded inside the C-shaped half-wavelength resonator after being folded.
The three-passband filter based on the SLR structure is characterized in that: and after folding, the first open-circuit branch is bent to one side of the C-shaped half-wavelength resonator which is not loaded with the first short-circuit branch.
The three-passband filter based on the SLR structure is characterized in that: the first multi-branch asymmetric loading resonator unit and the second multi-branch asymmetric loading resonator unit are electrically coupled to form a filter.
The three-passband filter based on the SLR structure is characterized in that: the first input/output feeder line and the second input/output feeder line are placed in a zero-degree feeding mode, the loading position of the first input/output feeder line is arranged on the other side of the first short-circuit branch of the first half-wavelength resonator, and the loading position of the second input/output feeder line is arranged on the other side of the second short-circuit branch of the second half-wavelength resonator.
The three-passband filter based on the SLR structure is characterized in that: the back part of the microstrip substrate is a grounding metal plate.
The invention has the beneficial effects that: the three-passband filter is designed by utilizing the branch loading resonators or the asymmetric branch loading resonators, and is generated through the harmonic characteristics of the three-passband filter, so that the frequency adjustment is difficult, a certain parameter is changed independently sometimes, the three passbands are changed along with the change of the certain parameter, and in addition, the defect that the harmonic characteristic analysis is difficult is also caused. The multi-branch asymmetric loading resonator can be regarded as a set of a short-circuit branch asymmetric loading resonator and an open-circuit branch symmetric loading resonator, and the two resonators share one half-wavelength resonator. A three-passband filter is decomposed into two dual-passband filters, the design is simpler, and the analysis of factors influencing the passband frequency of the filter is more visual. Meanwhile, certain branches of the filter are folded to a certain extent, so that the circuit area of the filter can be reduced, and the miniaturization is facilitated.
Compared with the prior art, the invention has the remarkable characteristics that: 1) the three-passband filter realized by the SLR structure has low insertion loss and good in-band selection performance; 2) the frequencies of the first, second and third pass bands of the three-pass band filter are respectively mainly influenced by the lengths of the short-circuit branch, the half-wavelength resonator and the open-circuit branch, and can be flexibly adjusted within a certain range; 3) the bandwidth of the passband can be adjusted by changing the physical width of the minor matters; 4) the three-passband filter has a simple structure, realizes miniaturization, and is easy to process.
Drawings
Fig. 1 is a schematic structural diagram of a multi-branch asymmetrically loaded resonator unit in accordance with the present invention.
Fig. 2 is a schematic front view of a three-passband filter based on the SLR structure of the present invention.
Fig. 3 is a simulation curve of the frequency response of the three-passband filter based on the SLR structure of the present invention.
FIG. 4 is a frequency response simulation curve of the present invention as the length of the open-circuit stub of the multi-stub asymmetrically loaded resonator varies.
Description of reference numerals: the device comprises a first half-wavelength resonator 1, a second half-wavelength resonator 2, a first open-circuit branch 3, a second open-circuit branch 4, a first short-circuit branch 5, a second short-circuit branch 6, a first multi-branch asymmetric loading resonator unit 7, a second multi-branch asymmetric loading resonator unit 8, a first input/output feeder line 9 and a second input/output feeder line 10.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
As shown in fig. 1 and fig. 2, the three-passband filter based on the SLR structure of the present invention includes a microstrip substrate, the back side of the microstrip substrate is used as a grounding metal plate, the front side of the microstrip substrate is provided with a first input/output feeder 9, a second input/output feeder 10, a first multi-stub asymmetrically loaded resonator unit 7, and a second multi-stub asymmetrically loaded resonator unit 8, and the first asymmetrically loaded resonator unit 7 and the first input/output feeder 9 are distributed in a centrosymmetric manner with respect to the second multi-stub asymmetrically loaded resonator unit 8 and the second input/output feeder 10.
As shown in fig. 2, the first asymmetrically loaded resonator unit 7 of the present invention includes a first half-wavelength resonator 1, a first open stub 3 and a first short stub 5, wherein the first open stub 3 is loaded at the symmetrical line of the first half-wavelength resonator 1, and the first short stub 5 is loaded at the asymmetrical line of the first half-wavelength resonator 1.
The first multi-branch asymmetric loading resonator unit 7 is folded into a C shape, the two ends of the first multi-branch asymmetric loading resonator unit are folded into an S shape, and the first open-circuit branch 3 is folded into an L shape. The first open-circuit branch 3 and the first short-circuit branch 5 are loaded in the C-shaped half-wavelength resonator. The first open-circuit stub 3 is bent to the side of the C-shaped half-wavelength resonator to which the first short-circuit stub 5 is not applied. The first multi-branch asymmetric loading resonator unit 7 and the second multi-branch asymmetric loading resonator unit 8 are electrically coupled to form a filter and are distributed in a centrosymmetric manner.
The first input/output feeder 9 and the second input/output feeder 10 are placed in a zero-degree feeding mode, and the loading position of the first input/output feeder 9 is arranged on the other side of the first short-circuit branch 5 of the first half-wavelength resonator 1.
The multi-branch asymmetric loading resonator can be regarded as a set of a short-circuit branch asymmetric loading resonator and an open-circuit branch symmetric loading resonator, and the two resonators share one half-wavelength resonator. A three-passband filter is decomposed into two dual-passband filters, the design is simpler, and the analysis of factors influencing the passband frequency of the filter is more visual. Meanwhile, certain branches of the filter are folded to a certain extent, so that the circuit area of the filter can be reduced, and the miniaturization is facilitated.
In embodiment 1 of the present invention, the third passband frequency of the three-passband filter is near 5.25GHz, and is mainly generated by an open-circuit stub in the multi-stub asymmetric loading resonance unit, and the physical length of the open-circuit stub is adjusted to move the position of the third passband, so that the physical length of the open-circuit stub is reduced to move the third passband frequency in a direction greater than 5.25GHz, and the frequencies of the first and second passbands are not changed. The first passband frequency of the three-passband filter is near 2.45GHz and is mainly generated by a short-circuit branch in the multi-branch asymmetric loading resonance unit, and the second passband frequency is near 3.5GHz and is mainly generated by a half-wavelength resonator in the multi-branch asymmetric loading resonance unit. In the same way, the physical length of the short-circuit branch knot is changed, so that the frequencies of the first passband and the second passband can be adjusted, and the frequency of the third passband cannot be influenced.
The first passband of the filter is mainly affected by the length of the short-circuit branch, the second passband frequency is mainly affected by the physical length of the half-wavelength resonator, and the third passband is mainly affected by the length of the open-circuit branch. The width of the short-circuit branch is adjusted, so that the bandwidth of the first and second pass bands can be changed, and the selectivity of the filter is improved.
The figure of merit, f, can be calculated according to the following formula0Is the center frequency, BW3dBIs a 3dB bandwidth, with higher Q values representing greater selectivity for the passband. Where the center frequency of the third pass band is 5.25GHz and the 3dB bandwidth is 0.29GHz, the Q value is 18.1.
As an experimental scheme, the dielectric constant of the microstrip substrate is 3.66, the thickness is 0.762mm, and the loss tangent is 0.0037.
The beneficial effects of the invention can be further illustrated by the following simulation experiment:
experiment one: simulating the frequency response characteristic of the three-passband filter based on the SLR structure by using high-frequency simulation software Ansoft HFSS 15.0, wherein the frequency characteristic comprises the following steps: an S21 (insertion loss) parameter and an S11 (return loss) parameter.
As shown in fig. 3, the frequency characteristics include: an S21 (insertion loss) parameter and an S11 (return loss) parameter.
The abscissa represents the frequency component in GHz and the left ordinate represents the amplitude variation in dB. As can be seen from FIG. 3, there are three pass bands at frequencies of 2.4GHz, 3.5GHz and 5.2GHz, the insertion loss is less than 2dB, and the return loss is greater than 15 dB. And two transmission zeros are arranged at the frequencies of 2.8GHz and 3.9GHz, so that the filter has good selectivity.
Experiment two: simulating the frequency response characteristics of the three-passband filter with different open-circuit branch lengths by using high-frequency simulation software Ansoft HFSS 15.0, wherein the frequency characteristics comprise: s21 (insertion loss) parameter.
As shown in fig. 4, the frequency characteristics include: s21 (insertion loss) parameter. The abscissa represents the frequency component in GHz and the left ordinate represents the amplitude variation in dB. As can be seen from fig. 4, the frequency of the third pass band can be changed by adjusting the length of the open stub.
Claims (7)
1. The utility model provides a three passband filter based on SLR structure, including the microstrip base plate, microstrip base plate front portion has first input/output feeder (9), second input/output feeder (10), first many branches of asymmetric loading resonator unit (7), second many branches of asymmetric loading resonator unit (8), first many branches of asymmetric loading resonator unit (7), first input/output feeder (9) are central symmetry distribution for second many branches of asymmetric loading resonator unit (8) and second input/output feeder (10), second many branches of asymmetric loading resonator unit (8) and first many branches of asymmetric loading resonator unit (7) the same structure, its characterized in that: the first asymmetric loading resonator unit 7 comprises a first half-wavelength resonator (1), a first open-circuit branch (3) and a first short-circuit branch (5), wherein the first open-circuit branch (3) is loaded at the symmetrical line of the first half-wavelength resonator (1), and the first short-circuit branch (5) is loaded at the asymmetrical line of the first half-wavelength resonator (1).
2. The three-passband filter based on the SLR structure as claimed in claim 1, wherein: the first multi-branch asymmetric loading resonator unit (7) is folded into a C shape, the two ends are folded into an S shape, and the first open-circuit branch (3) is folded into an L shape.
3. The three-passband filter based on the SLR structure of claim 2, wherein: the first open-circuit branch (3) and the first short-circuit branch (5) are folded and loaded in the C-shaped half-wavelength resonator.
4. A three-passband filter based on an SLR structure as claimed in claim 2 or claim 3, wherein: after folding, the first open-circuit branch (3) is bent towards one side of the C-shaped half-wavelength resonator which is not loaded with the first short-circuit branch (5).
5. A three-passband filter based on an SLR structure as claimed in claim 2 or claim 3, wherein: the first multi-branched asymmetrically loaded resonator unit (7) and the second multi-branched asymmetrically loaded resonator unit (8) are electrically coupled into a filter.
6. A three-passband filter based on an SLR structure as claimed in claim 1 or claim 2, wherein: the first input/output feeder line (9) and the second input/output feeder line (10) are placed in a zero-degree feeding mode, the loading position of the first input/output feeder line (9) is located on the other side of the first short-circuit branch (5) of the first half-wavelength resonator (1), and the loading position of the second input/output feeder line (10) is located on the other side of the second short-circuit branch (6) of the second half-wavelength resonator (2).
7. A three-passband filter based on an SLR structure as claimed in claim 1 or claim 2, wherein: the back part of the microstrip substrate is a grounding metal plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110310572.XA CN113224483A (en) | 2021-03-23 | 2021-03-23 | Three-passband filter based on SLR structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110310572.XA CN113224483A (en) | 2021-03-23 | 2021-03-23 | Three-passband filter based on SLR structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113224483A true CN113224483A (en) | 2021-08-06 |
Family
ID=77083938
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110310572.XA Pending CN113224483A (en) | 2021-03-23 | 2021-03-23 | Three-passband filter based on SLR structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113224483A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114824701A (en) * | 2022-04-20 | 2022-07-29 | 中国电子科技集团公司第三十六研究所 | Double-frequency filter |
| CN114915276A (en) * | 2022-05-11 | 2022-08-16 | 西南交通大学 | Amplitude limiting filtering structure for radio frequency front end electromagnetic protection |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102637931A (en) * | 2012-04-18 | 2012-08-15 | 南通大学 | Microwave three-passband bandpass filter |
| CN103326090A (en) * | 2013-05-22 | 2013-09-25 | 华东交通大学 | Tee joint band high-temperature superconducting filter |
| CN106602185A (en) * | 2016-12-07 | 2017-04-26 | 中国船舶重工集团公司第七〇九研究所 | Dual-bandpass filter based on nonsymmetric short circuit stub loaded resonator |
-
2021
- 2021-03-23 CN CN202110310572.XA patent/CN113224483A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102637931A (en) * | 2012-04-18 | 2012-08-15 | 南通大学 | Microwave three-passband bandpass filter |
| CN103326090A (en) * | 2013-05-22 | 2013-09-25 | 华东交通大学 | Tee joint band high-temperature superconducting filter |
| CN106602185A (en) * | 2016-12-07 | 2017-04-26 | 中国船舶重工集团公司第七〇九研究所 | Dual-bandpass filter based on nonsymmetric short circuit stub loaded resonator |
Non-Patent Citations (2)
| Title |
|---|
| MANIMALA PAL等: "A Distinctive Resonance：Multiband Bandpass Filter Design Techniques Using Multimode Resonators", 《IEEE MICROWAVE MAGAZINE》 * |
| MOHAMMED FADHEL HASAN等: "Compact Dual-band Microstrip Band Pass Filter Design Based on Stub Loaded Resonator for Wireless Applications", 《2017 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM — SPRING (PIERS)》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114824701A (en) * | 2022-04-20 | 2022-07-29 | 中国电子科技集团公司第三十六研究所 | Double-frequency filter |
| CN114824701B (en) * | 2022-04-20 | 2024-01-19 | 中国电子科技集团公司第三十六研究所 | Dual-frequency filter |
| CN114915276A (en) * | 2022-05-11 | 2022-08-16 | 西南交通大学 | Amplitude limiting filtering structure for radio frequency front end electromagnetic protection |
| CN114915276B (en) * | 2022-05-11 | 2023-11-10 | 西南交通大学 | Amplitude limiting filter structure for electromagnetic protection of radio frequency front end |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110034361B (en) | Miniaturized ultra-wideband filtering power division feed network for 5G communication and design method thereof | |
| CN112332054B (en) | Dual-passband band-pass filter based on asymmetric coupling line | |
| CN109755703B (en) | Differential dual-frequency band-pass filter with high selectivity | |
| CN110137643B (en) | Large-frequency-ratio coaxial cavity dual-frequency filter with controllable bandwidth | |
| CN113224483A (en) | Three-passband filter based on SLR structure | |
| CN102610879A (en) | Double-frequency band-pass filter | |
| Keshavarz et al. | Low profile metamaterial band-pass filter loaded with 4-turn complementary spiral resonator for WPT applications | |
| CN208385587U (en) | A kind of small-sized three band-pass filter with eight transmission zeros | |
| CN106848507A (en) | Double-band-pass microstrip filter based on combination resonator | |
| CN112768854B (en) | High-selectivity differential dual-passband microstrip filter based on stepped impedance resonator | |
| CN111403861B (en) | UIR loaded three-order dual-passband substrate integrated waveguide filter | |
| CN112072242A (en) | Filter structure and filter | |
| CN202523822U (en) | Double-frequency band pass filter | |
| CN109728388B (en) | High-selectivity electrically-tunable coaxial filter with constant absolute bandwidth | |
| CN111293390A (en) | UIR loaded three-order dual-passband substrate integrated waveguide filter | |
| CN212434808U (en) | Filter structure and filter | |
| CN211578932U (en) | T-type loaded dual-passband microstrip filter | |
| CN202084620U (en) | Novel band stop structure combiner | |
| CN112310583B (en) | T-shaped dual-mode resonator-based three-passband filter | |
| Xia et al. | Dual-band bandpass filters using SIRs with open-stub line and zero-degree feed structure | |
| King et al. | A microstrip diplexer using folded hairpins | |
| Zhou et al. | Isosceles triangular cavity based dual-band SIW filters for 5G millimeter-wave systems | |
| CN114639930B (en) | High passband isolation's dual-passband filter | |
| CN211238454U (en) | UIR loaded three-order dual-passband substrate integrated waveguide filter | |
| CN212323180U (en) | Communication device and filter thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20210806 |