CN111710946A - Single-end type microstrip stub band-pass filter of broadband - Google Patents
Single-end type microstrip stub band-pass filter of broadband Download PDFInfo
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- CN111710946A CN111710946A CN202010510236.5A CN202010510236A CN111710946A CN 111710946 A CN111710946 A CN 111710946A CN 202010510236 A CN202010510236 A CN 202010510236A CN 111710946 A CN111710946 A CN 111710946A
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- patch capacitor
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- pass filter
- microstrip line
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- 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
Abstract
The invention discloses a single-end microstrip stub band-pass filter of a broadband, which comprises a first feeder line, a second feeder line, an eighth-wavelength coupling microstrip line, first to fourth patch capacitors, a first metalized through hole and a second metalized through hole. One end of the eighth wavelength coupling microstrip line is connected with the first feeder line, the second feeder line, the first patch capacitor, the third patch capacitor and the fourth patch capacitor, and the other end of the eighth wavelength coupling microstrip line is grounded through the first metalized through hole. The first patch capacitor is loaded on the inner side of one end of the coupling microstrip line in series, the third patch capacitor and the fourth patch capacitor are loaded on the outer side of one end of the coupling microstrip line in parallel, and the other ends of the third patch capacitor and the fourth patch capacitor are grounded through the second metalized through hole. The second patch capacitor is loaded in series at the inner side of the middle part of the coupling microstrip line. Compared with the existing broadband single-end type microstrip band-pass filter, the broadband band-pass filter has the advantages that the circuit size is greatly reduced while the broadband filtering response is obtained, the loss is extremely low, and the structure is simple.
Description
Technical Field
The invention relates to the field of microwave communication, in particular to a broadband single-end type microstrip short-line band-pass filter.
Background
With the development of wireless communication technology, a wireless system needs to be compatible with multiple standards and multiple functions, and microwave devices are promoted to develop towards miniaturization, broadband and low loss. The single-end band-pass filter is an important component of a wireless communication system, and the single-end band-pass filter realized by utilizing the microstrip line is beneficial to the integration and low cost of the system, and is particularly widely applied to microwave frequency bands. Therefore, the realization of the single-ended microstrip bandpass filter with small size, broadband and low loss meets the development trend of the current wireless communication system, but the design of such microstrip bandpass filter still remains an important challenge at present.
The traditional single-end type microstrip band-pass filter mainly adopts methods of a multimode resonator, a multi-branch loaded resonator, a multimode resonator loaded by annular open-circuit branches, a three-wire coupling structure loaded by multi-branches and defected grounds and the like to realize broadband response. However, the single-end microstrip bandpass filter adopting the conventional design method has the problem of large size, mainly comes from the problem of large size of the resonator or extra loading branches, and also has the problems of complex structure, high loss and the like. In order to effectively reduce the size of the broadband single-ended microstrip band-pass filter, various design methods are proposed, including methods of adopting a quarter-wavelength three-wire coupling structure, a combination of folding branches and fan-shaped branches, a cross-coupling quarter-wavelength step impedance resonator and the like. Although these design methods constitute filters that are significantly reduced in size compared to conventional implementations, the size of such designs has yet to be further reduced as wireless communication technology advances. Therefore, it is necessary to provide a novel broadband single-ended microstrip bandpass filter, which further reduces the size, reduces the loss, ensures the broadband, and simplifies the structure.
Disclosure of Invention
The purpose of the invention is as follows: in view of the prior art, a broadband single-ended microstrip stub bandpass filter is provided, which achieves miniaturization of the broadband single-ended microstrip bandpass filter and maintains broadband response and low loss performance.
The technical scheme is as follows: a single-end microstrip stub band-pass filter of a broadband comprises a first feeder line, a second feeder line, an eighth wavelength coupling microstrip line, first to fourth patch capacitors, a first metalized through hole and a second metalized through hole; one end of the one-eighth wavelength coupling microstrip line is connected with the first feeder line, the second feeder line, the first patch capacitor, the third patch capacitor and the fourth patch capacitor, and the other end of the one-eighth wavelength coupling microstrip line is grounded through the first metalized through hole; the first patch capacitor is serially loaded on the inner side of one end of the one-eighth wavelength coupling microstrip line, the third patch capacitor and the fourth patch capacitor are parallelly loaded on the outer side of one end of the coupling microstrip line, and the other ends of the third patch capacitor and the fourth patch capacitor are grounded through the second metalized through hole; the second patch capacitor is loaded in series at the inner side of the middle part of the one-eighth wavelength coupling microstrip line.
Has the advantages that: compared with the existing broadband single-end type microstrip band-pass filter, the broadband band-pass filter has the advantages that the circuit size is greatly reduced while the broadband filtering response is obtained, the loss is extremely low, and the structure is simple. The method has the following specific advantages:
1. a single one-eighth wavelength short-circuit coupling microstrip line is utilized, series and parallel patch capacitors are loaded at specific positions, and a small-size and low-loss broadband single-end type microstrip band-pass filter is realized.
2. The patch capacitor 5 is loaded in series at the inner side of the middle part of the coupling microstrip line, and the patch capacitors 6 and 7 are loaded in parallel at the outer side of one end of the coupling microstrip line, so that the whole filter obtains broadband and low-loss filter response.
3. The patch capacitor 4 is loaded in series at the inner side of one end of the coupling microstrip line, so that the whole filter obtains a plurality of transmission paths, an extra transmission zero point is generated, and the out-of-band rejection and the frequency selectivity of the filter are improved.
Drawings
FIG. 1 is a schematic diagram of a bandpass filter according to the present invention;
fig. 2 is a simulation result of the frequency response of the band-pass filter of the embodiment.
Detailed Description
The invention is further explained below with reference to the drawings.
A single-end microstrip short-line band-pass filter of a broadband adopts a single-layer microstrip structure, and comprises a first feeder line 1, a second feeder line 2, an eighth wavelength coupling microstrip line 3, first to fourth patch capacitors 4, 5, 6 and 7, and first and second metalized through holes 8 and 9 as shown in figure 1. One end of the one-eighth wavelength coupling microstrip line 3 is connected with the first feeder line 1, the second feeder line 2, the first patch capacitor 4, the third patch capacitor 6 and the fourth patch capacitor 7, and the other end is grounded through the first metalized through hole 8. The first patch capacitor 4 is loaded on the inner side of one end of the one-eighth wavelength coupling microstrip line 3 in series, the third patch capacitor 6 and the fourth patch capacitor 7 are loaded on the outer side of one end of the coupling microstrip line in parallel, and the other ends of the third patch capacitor 6 and the fourth patch capacitor 7 are grounded through the second metalized through hole 9. The second patch capacitor 5 is loaded in series at the inner side of the middle part of the eighth wavelength coupling microstrip line 3. The signal is input from the first feed line 1 and output from the second feed line 2 after passing through the entire circuit.
The broadband single-end type microstrip short-line band-pass filter can obtain broadband low-loss filter response only by one eighth wavelength coupling line in a series-parallel capacitance loading mode at a specific position, and is very compact and simple in structure. The parallel-loaded patch capacitors 6 and 7 and the series-loaded patch capacitor 5 can effectively change the electric field distribution of the coupling line, so that the whole filter can work at a frequency corresponding to one eighth of the wavelength electric length. The patch capacitor 4 loaded in series additionally provides a signal transmission channel for the whole filter, so that the filter has the possibility of phase cancellation at a specific frequency point, and therefore, additional transmission zero points can be brought, and frequency selectivity and out-of-band rejection are provided. The bandwidth of the filter is controlled by the distance between the coupling lines and the capacitance value of the loading capacitor, the control of the center frequency is mainly based on the length of the coupling lines and assisted by the capacitance value of the capacitor, the high-end frequency transmission zero point can be independently controlled by the patch capacitor 4, and the low-end frequency transmission zero point is jointly controlled by the coupling amount of the coupling lines and the loading capacitor.
In the embodiment, an RO4003C substrate is adopted, the dielectric constant of the RO4003C substrate is 3.38, the loss angle of the RO4003C substrate is 0.0027, the thickness of the RO4003 substrate is 0.813mm, as shown in FIG. 2, the center frequency is 1.5GHz, the relative bandwidth of 3-dB is 88.9%, the minimum insertion loss is only 0.11dB, four transmission zeros are respectively located at 0GHz, 0.62GHz, 2.47GHz and 4.87GHz, and the suppression of more than 15dB can be realized in the out-of-band frequency range of 2.34GHz to 5.92GHz, the physical size of the design is 15.2mm × 3.6.6 mm, and the corresponding electrical size is only 0.138 lambdag×0.032λg，λgThe guided wave wavelength corresponding to the center frequency.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (1)
1. A single-end microstrip short-line band-pass filter of a broadband is characterized by comprising a first feeder line (1), a second feeder line (2), an eighth wavelength coupling microstrip line (3), first to fourth patch capacitors (4, 5, 6, 7), first and second metalized through holes (8, 9); one end of the one-eighth wavelength coupling microstrip line (3) is connected with the first feeder line (1), the second feeder line (2), the first patch capacitor (4), the third patch capacitor (6) and the fourth patch capacitor (7), and the other end of the one-eighth wavelength coupling microstrip line is grounded through the first metalized through hole (8); the first patch capacitor (4) is serially loaded on the inner side of one end of the one-eighth wavelength coupling microstrip line (3), the third patch capacitor (6) and the fourth patch capacitor (7) are parallelly loaded on the outer side of one end of the coupling microstrip line, and the other ends of the third patch capacitor (6) and the fourth patch capacitor (7) are grounded through a second metalized through hole (9); the second patch capacitor (5) is loaded in series at the inner side of the middle part of the eighth wavelength coupling microstrip line (3).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010510236.5A CN111710946A (en) | 2020-06-08 | 2020-06-08 | Single-end type microstrip stub band-pass filter of broadband |
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| CN202010510236.5A CN111710946A (en) | 2020-06-08 | 2020-06-08 | Single-end type microstrip stub band-pass filter of broadband |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114024108A (en) * | 2021-10-28 | 2022-02-08 | 南湖实验室 | Miniaturized reconfigurable microstrip low-pass filter |
| CN115458882A (en) * | 2022-09-14 | 2022-12-09 | 南通先进通信技术研究院有限公司 | Compact balanced type broadband phase shifter |
| CN115799781A (en) * | 2022-11-16 | 2023-03-14 | 宜确半导体（苏州）有限公司 | Coupling line band-pass filter |
-
2020
- 2020-06-08 CN CN202010510236.5A patent/CN111710946A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114024108A (en) * | 2021-10-28 | 2022-02-08 | 南湖实验室 | Miniaturized reconfigurable microstrip low-pass filter |
| CN115458882A (en) * | 2022-09-14 | 2022-12-09 | 南通先进通信技术研究院有限公司 | Compact balanced type broadband phase shifter |
| CN115458882B (en) * | 2022-09-14 | 2023-08-25 | 南通先进通信技术研究院有限公司 | Balance type broadband phase shifter |
| CN115799781A (en) * | 2022-11-16 | 2023-03-14 | 宜确半导体（苏州）有限公司 | Coupling line band-pass filter |
| CN115799781B (en) * | 2022-11-16 | 2024-02-02 | 宜确半导体（苏州）有限公司 | Coupled line band-pass filter |
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