CN211150738U - Dual-passband adjustable microstrip filter - Google Patents
Dual-passband adjustable microstrip filter Download PDFInfo
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- CN211150738U CN211150738U CN202020139098.XU CN202020139098U CN211150738U CN 211150738 U CN211150738 U CN 211150738U CN 202020139098 U CN202020139098 U CN 202020139098U CN 211150738 U CN211150738 U CN 211150738U
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- microstrip line
- coupling
- vibrating arm
- shaped structure
- resonance unit
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- 230000008878 coupling Effects 0.000 claims abstract description 39
- 238000010168 coupling process Methods 0.000 claims abstract description 39
- 238000005859 coupling reaction Methods 0.000 claims abstract description 39
- 239000003990 capacitor Substances 0.000 claims abstract description 19
- 238000006880 cross-coupling reaction Methods 0.000 claims abstract description 17
- 239000000758 substrate Substances 0.000 claims abstract description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 239000010949 copper Substances 0.000 claims abstract description 7
- 230000009977 dual effect Effects 0.000 claims description 7
- 230000005611 electricity Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
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Abstract
The utility model discloses a dual-passband adjustable microstrip filter, which comprises a substrate, wherein the upper layer of the substrate is provided with a microstrip line structure, the lower layer of the substrate is covered with a copper bottom plate, the microstrip line structure comprises four half-wavelength resonance units with two different high and low frequency bands, the four resonance units feed electricity to the microstrip line structure through electric coupling, the two resonance units with the same frequency band are mutually coupled, variable capacitors are respectively added at the terminals of the two resonance units with the low frequency band, tuning of the central frequency of the low frequency band is realized by changing the capacitance value of the capacitors, and a cross-coupling microstrip line adopts a cross-coupling structure to improve the coupling strength, the two ends of the cross-coupling microstrip line are respectively connected with AN input end and AN output end, the filter meets the basic performance standard, simultaneously, the central frequency can resonate between two frequency points of 2.46GHz and 3.48GHz, can cover two frequency bands of W L AN and WIMAX, the central frequency can tune between 2.34GHz and 2.46GHz and 3.38GHz and 3.48GHz, and has good tuning capability.
Description
Technical Field
The utility model belongs to the technical field of wireless communication and specifically relates to a dual passband adjustable microstrip filter is related to.
Background
A filter is a key device in electronic communication applications, and is used to select a desired signal required by a system in a complex electromagnetic environment, and to filter out unwanted interference, thereby reducing the response of the system to unwanted signals, and the operating performance of the filter directly affects the signal quality of the entire wireless communication system. Therefore, how to design a filter with high performance is of great significance to design microwave circuit systems.
SUMMERY OF THE UTILITY MODEL
Utility model purpose: in order to overcome the not enough of background art, the utility model discloses a dual-passband adjustable microstrip filter.
The technical scheme is as follows: double passband adjustable microstrip filter, include: the micro-strip line structure is arranged on the upper layer of the substrate, and the copper bottom plate is covered on the lower layer of the substrate;
the microstrip line structure includes:
four half-wavelength resonance units with different high and low frequency bands are fed by electric coupling, the two resonance units with the same frequency band are mutually coupled, variable capacitors are respectively added at the terminals of the two resonance units with the low frequency band, and the tuning of the central frequency of the low frequency band is realized by changing the capacitance values of the capacitors;
the cross-coupling microstrip line adopts a cross-finger coupling structure to improve the coupling strength, and two ends of the cross-coupling microstrip line are respectively connected with the input end and the output end.
Furthermore, the four half-wavelength resonance units are microstrip lines with different bent impedances.
Furthermore, the surface of the microstrip line structure is covered with a copper layer.
Furthermore, the four resonance units are open-circuit resonance units and comprise a first resonance unit, a second resonance unit, a third resonance unit and a fourth resonance unit, the first resonance unit and the second resonance unit, and the third resonance unit and the fourth resonance unit are respectively arranged symmetrically about a cross axis of the cross-coupling microstrip line, and the first resonance unit, the second resonance unit, the third resonance unit and the fourth resonance unit are respectively arranged on two sides of the cross-coupling microstrip line.
Furthermore, a first vibrating arm, a second vibrating arm and a third vibrating arm are sequentially connected to form a first U-shaped structure, a fourth vibrating arm, a fifth vibrating arm and a sixth vibrating arm are sequentially connected to form a second U-shaped structure, the second U-shaped structure is arranged in the first U-shaped structure, openings of the second U-shaped structure face outwards, the end parts of the first U-shaped structure and the second U-shaped structure are connected through a seventh vibrating arm to form a first resonance unit, and a capacitor is added at the other end of the first U-shaped structure; the second resonance unit and the first resonance unit have the same structure and are connected through a magnetic coupling gap between two adjacent vibration arms.
Further, the cross-coupled microstrip line includes a first coupled microstrip line connected to the input terminal and a second coupled microstrip line connected to the output terminal, the first coupled microstrip line includes a first microstrip line, one end of the first microstrip line is connected to the input terminal, the other end of the first microstrip line is connected to the second microstrip line along the extending direction, the connecting terminal extends in the vertical direction to form a third microstrip line, the second microstrip line and the third microstrip line are respectively arranged at intervals with the first vibrating arm and the second vibrating arm, the first resonant unit is fed through a gap between the first microstrip line and the second microstrip line, and the other end of the second microstrip line extends in the other vertical direction to form a fourth microstrip line; the first coupling microstrip line and the second coupling microstrip line are arranged symmetrically relative to the magnetic coupling gap axis, and two microstrip lines perpendicular to the microstrip line are respectively arranged between the fourth microstrip line and the fifth microstrip line at intervals in a crossed manner, so as to form electric coupling between source loads.
Furthermore, an eighth vibrating arm, a ninth vibrating arm and a tenth vibrating arm are sequentially connected to form a third U-shaped structure, an eleventh vibrating arm, a twelfth vibrating arm and a thirteenth vibrating arm are sequentially connected to form a fourth U-shaped structure, the third U-shaped structure is arranged in the fourth U-shaped structure, openings of the third U-shaped structure and the fourth U-shaped structure face outwards, the end portions of the third U-shaped structure and the fourth vibrating arm are connected through the fourteenth vibrating arm to form a third resonance unit, a capacitor is added to the other end of the third U-shaped structure, feeding is provided through a gap between the second microstrip line and the fourteenth vibrating arm, the third resonance unit and the fourth resonance unit are identical in structure, and the third resonance unit and the fourth resonance unit are connected through a magnetic coupling gap between two.
The filter has the advantages that compared with the prior art, the filter has the advantages that firstly, the resonance structure of two different frequency bands is designed, the double frequency bands can be independently tuned, the performance of one frequency band is not affected while the center frequency of the other frequency band is tuned, secondly, the resonance unit of the filter is realized by a half-wavelength resonator, and the magnetic coupling of the resonance unit does not use a metal through hole, so that the influence of the error of manufacturing the metal through hole on the performance of the filter is reduced, thirdly, the filter can achieve resonance between two frequency points of 2.46GHz and 3.48GHz while meeting the basic performance standard, can cover two frequency bands of W L AN and WIMAX, has good tuning capability because the center frequency can be tuned between 2.34GHz and 2.46GHz and between 3.38GHz and 3.48GHz, fourthly, has the capability of simultaneously generating transmission zero points on two sides of the resonance frequency, can improve the suppression capability of the filter, fifthly, has a novel structure and small size, occupies the volume of only 20.2mm and 14mm, and is easy to process at low cost.
Drawings
Fig. 1 is a schematic diagram of the filter structure of the present invention;
FIG. 2 is a topological structure diagram of the present invention;
fig. 3 is a structural diagram of the first resonator and the second resonator of the present invention;
fig. 4 is a cross-coupled microstrip line structure diagram of the present invention;
fig. 5 is a structural diagram of a third resonator and a fourth resonator of the present invention;
fig. 6 shows the S parameter when the capacitance C1 is added to the open end of the first resonator and the second resonator, and other values are fixed and the capacitance value is changed;
fig. 7 shows the S parameter when the capacitance C2 is added to the open end of the third resonator and the open end of the fourth resonator, and the other values are fixed and the capacitance value is changed.
Detailed Description
The technical solution of the present invention will be further explained with reference to the accompanying drawings and examples.
The dual-passband tunable microstrip filter shown in fig. 1, using FR4 as the substrate, was copper-etched on both sides of FR4 with dimensions of 24.8mm by 25mm by 0.8 mm.
The method comprises the following steps: the micro-strip line structure comprises a substrate 1, wherein a micro-strip line structure is arranged on the upper layer of the substrate 1, and a copper bottom plate is covered on the lower layer;
the microstrip line structure includes:
four half-wavelength resonance units with different high and low frequency bands are fed by electric coupling, the two resonance units with the same frequency band are mutually coupled, variable capacitors are respectively added at the terminals of the two resonance units with the low frequency band, and the tuning of the central frequency of the low frequency band is realized by changing the capacitance values of the capacitors;
the microstrip line 2 is cross-coupled, the cross-coupled microstrip line 2 adopts a cross-finger coupling structure to improve the coupling strength, and two ends of the cross-coupled microstrip line 2 are respectively connected with the input end 201 and the output end 202.
The filter is symmetrical about a central plane, and mainly comprises four half-wavelength open-circuit resonant units with two different frequency bands and a source load cross-coupling structure, wherein each resonant unit is in a folded shape, so that the space occupied by the resonant units can be saved, and the size of the filter is reduced.
The four half-wavelength resonance units are microstrip lines with different bent impedances.
The surface of the microstrip line structure is covered with a copper layer.
Because the topological structure of the filter has cross coupling and coupling between resonators, signals are subjected to phase shift when passing through the filter, a phase difference of 180 degrees is generated at an output end, transmission zero points are respectively generated at two sides of a pass band, and out-of-band rejection of the filter is improved. By controlling the size of the variable capacitor, the tuning of the low-frequency band center frequency of the filter is realized. And the magnetic coupling between the resonance units is realized by utilizing half-wavelength resonance, so that the influence of the error of manufacturing the metal through hole on the performance of the filter is reduced.
As shown in FIG. 2, in conjunction with FIG. 1, the filter is capable of forming three channels, 1, S-L, 2, S-1-2-L, 3, S-3-4-L, where MS1, M L2, MS3, M L4, MS L are represented as electrical couplings and M12 and M34 are represented as magnetic couplings.
In the high-end case of the passband: the signal reaches the output end through the channel 1, and the phase is shifted by +90 degrees; the signal reaches the output end through the channel 2 or 3, and the phase is shifted by-90 degrees;
in the case of the low end of the passband: the signal reaches the output end through the channel 1, and the phase is shifted by +90 degrees; the signal reaches the output end through the channel 2 or 3, and the phase is shifted by +270 degrees;
when the signal reaches the output end through the filter, a phase difference of 180 degrees is generated at the upper end and the lower end of the passband, so that transmission zero points are generated at the two ends.
The four resonance units are open-circuit resonance units and comprise a first resonance unit 3, a second resonance unit 4, a third resonance unit 5 and a fourth resonance unit 6, the first resonance unit 3 and the second resonance unit 4, the third resonance unit 5 and the fourth resonance unit 6 are symmetrically arranged about the crossed axis of the cross-coupling microstrip line 2 respectively, and the first resonance unit 3, the second resonance unit 4, the third resonance unit 5 and the fourth resonance unit 6 are respectively arranged on two sides of the cross-coupling microstrip line 2.
As shown in fig. 3, a first vibrating arm 301, a second vibrating arm 302, and a third vibrating arm 303 are sequentially connected to form a first U-shaped structure, a fourth vibrating arm 304, a fifth vibrating arm 305, and a sixth vibrating arm 306 are sequentially connected to form a second U-shaped structure, the second U-shaped structure is disposed in the first U-shaped structure, the openings of the second U-shaped structure are outward, the end portions of the first U-shaped structure and the second U-shaped structure are connected through a seventh vibrating arm 307 to form a first resonance unit 3, and a capacitor is added to the other end of the first U-shaped structure to achieve the purpose of tuning the center frequency by changing the capacitance value of the capacitor; the second resonance unit 4 has the same structure as the first resonance unit 3, and is connected by a magnetic coupling gap between two adjacent resonance arms.
As shown in fig. 4, the cross-coupled microstrip line 2 includes a first coupled microstrip line connected to the input terminal 201 and a second coupled microstrip line connected to the output terminal 202, the first coupled microstrip line includes a first microstrip line 203, one end of the first microstrip line 203 is connected to the input terminal 201, the other end of the first microstrip line is connected to the second microstrip line 204 along the extending direction, the connecting end extends in the vertical direction to form a third microstrip line 205, the second microstrip line 204 and the third microstrip line 205 are respectively disposed at an interval with the first vibrating arm 301 and the second vibrating arm 302, and provide power feed for the first resonant unit 3 through the gap therebetween, and the other end of the second microstrip line 204 extends in the other vertical direction to form a fourth microstrip line 206; the first coupling microstrip line and the second coupling microstrip line are arranged symmetrically relative to the magnetic coupling gap axis, two microstrip lines perpendicular to the microstrip line are respectively arranged between the fourth microstrip line 206 and the fifth microstrip line 207 which is symmetrical to the fourth microstrip line at intervals in a crossed manner, so as to form electric coupling between source loads, and the characteristics are as follows: the coupling strength and the lengths of the four microstrip lines present a positive correlation, and the coupling strength and the gaps between the four microstrip lines present an inverse correlation.
As shown in fig. 5, an eighth vibrating arm 501, a ninth vibrating arm 502, and a tenth vibrating arm 503 are sequentially connected to form a third U-shaped structure, an eleventh vibrating arm 504, a twelfth vibrating arm 505, and a thirteenth vibrating arm 506 are sequentially connected to form a fourth U-shaped structure, the third U-shaped structure is disposed in the fourth U-shaped structure, and has an opening facing outward, the ends of the third U-shaped structure and the fourth vibrating arm are connected through a fourteenth vibrating arm 507 to form a third resonant unit 5, a capacitor is added to the other end of the third U-shaped structure, the purpose of tuning the center frequency is achieved by changing the capacitance value of the capacitor, a feed is provided through a gap between the second microstrip line 204 and the fourteenth vibrating arm 507, and the third resonant unit 5 and the fourth resonant unit 6 have the same structure and are connected through a magnetic coupling gap between two adjacent vibrating arms.
The filter constructed according to the structure of fig. 1 can generate two transmission zeros in two different frequency bands as shown in fig. 6 and 7, thereby improving the out-of-band rejection degree of the filter.
Through the above description, the principle of the invention is:
the input end and the output end are coupled with four resonance units of two different frequency bands through electric coupling, the four resonance units generate resonance frequency response by resonance theory, the same frequency band is coupled and connected through two resonance unit gaps, as shown in fig. 6 and 7, the center frequencies of the two frequency bands are respectively about 2.45GHz and 3.48GHz, when the capacitor C1 is changed, the length of the resonance unit is changed, the center frequency of the W L AN frequency band can be shifted, and when the capacitor C2 is changed, the center frequency of WIMAX can be shifted.
Claims (7)
1. A dual passband adjustable microstrip filter comprising: the micro-strip line structure comprises a substrate (1), wherein a micro-strip line structure is arranged on the upper layer of the substrate (1), and a copper bottom plate is covered on the lower layer;
the microstrip line structure includes:
four half-wavelength resonance units with different high and low frequency bands are fed by electric coupling, the two resonance units with the same frequency band are mutually coupled, variable capacitors are respectively added at the terminals of the two resonance units with the low frequency band, and the tuning of the central frequency of the low frequency band is realized by changing the capacitance values of the capacitors;
the microstrip line (2) is in a cross-coupling structure, the cross-coupling microstrip line (2) improves coupling strength, and two ends of the cross-coupling microstrip line (2) are respectively connected with the input end (201) and the output end (202).
2. The dual passband adjustable microstrip filter according to claim 1 wherein: the four half-wavelength resonance units are microstrip lines with different bent impedances.
3. The dual passband adjustable microstrip filter according to claim 1 wherein: the surface of the microstrip line structure is covered with a copper layer.
4. The dual passband adjustable microstrip filter according to claim 1 wherein: the four resonance units are open-circuit resonance units and comprise a first resonance unit (3), a second resonance unit (4), a third resonance unit (5) and a fourth resonance unit (6), the first resonance unit (3), the second resonance unit (4), the third resonance unit (5) and the fourth resonance unit (6) are symmetrically arranged about a cross axis of the cross coupling microstrip line (2) respectively, and the first resonance unit (3), the second resonance unit (4), the third resonance unit (5) and the fourth resonance unit (6) are respectively arranged on two sides of the cross coupling microstrip line (2).
5. The dual-passband adjustable microstrip filter according to claim 4 wherein: the first vibrating arm (301), the second vibrating arm (302) and the third vibrating arm (303) are sequentially connected to form a first U-shaped structure, the fourth vibrating arm (304), the fifth vibrating arm (305) and the sixth vibrating arm (306) are sequentially connected to form a second U-shaped structure, the second U-shaped structure is arranged in the first U-shaped structure, the openings of the second U-shaped structure face outwards, the end parts of the second U-shaped structure and the first vibrating arm (307) are connected to form a first resonance unit (3), and a capacitor is added to the other end of the first U-shaped structure; the second resonance unit (4) and the first resonance unit (3) are identical in structure and are connected through a magnetic coupling gap between two adjacent vibration arms.
6. The dual passband adjustable microstrip filter according to claim 5 wherein: the cross-coupling microstrip line (2) comprises a first coupling microstrip line connected with an input end (201) and a second coupling microstrip line connected with an output end (202), the first coupling microstrip line comprises a first microstrip line (203), one end of the first microstrip line (203) is connected with the input end (201), the other end of the first microstrip line is connected with a second microstrip line (204) along the extension direction, the connection end extends towards the vertical direction to form a third microstrip line (205), the second microstrip line (204) and the third microstrip line (205) are respectively arranged with the first vibrating arm (301) and the second vibrating arm (302) at intervals, feed is provided for the first resonance unit (3) through a gap between the first microstrip line and the third microstrip line, and the other end of the second microstrip line (204) extends towards the other vertical direction to form a fourth microstrip line (206); the first coupling microstrip line and the second coupling microstrip line are arranged symmetrically relative to the magnetic coupling gap axis, and two microstrip lines perpendicular to the microstrip line are respectively arranged between the fourth microstrip line (206) and the fifth microstrip line (207) at intervals in a crossed manner to form electric coupling between source loads.
7. The dual passband adjustable microstrip filter according to claim 6 wherein: an eighth vibrating arm (501), a ninth vibrating arm (502) and a tenth vibrating arm (503) are sequentially connected to form a third U-shaped structure, an eleventh vibrating arm (504), a twelfth vibrating arm (505) and a thirteenth vibrating arm (506) are sequentially connected to form a fourth U-shaped structure, the third U-shaped structure is arranged in the fourth U-shaped structure, openings of the third U-shaped structure face outwards, the end portions of the third U-shaped structure and the fourth vibrating arm are connected through a fourteenth vibrating arm (507) to form a third resonant unit (5), a capacitor is added to the other end of the third U-shaped structure, feeding is provided through a gap between the second microstrip line (204) and the fourteenth vibrating arm (507), the third resonant unit (5) and the fourth resonant unit (6) are identical in structure, and are connected through a magnetic coupling gap between two adjacent vibrating arms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020139098.XU CN211150738U (en) | 2020-01-21 | 2020-01-21 | Dual-passband adjustable microstrip filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020139098.XU CN211150738U (en) | 2020-01-21 | 2020-01-21 | Dual-passband adjustable microstrip filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211150738U true CN211150738U (en) | 2020-07-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020139098.XU Expired - Fee Related CN211150738U (en) | 2020-01-21 | 2020-01-21 | Dual-passband adjustable microstrip filter |
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| Country | Link |
|---|---|
| CN (1) | CN211150738U (en) |
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2020
- 2020-01-21 CN CN202020139098.XU patent/CN211150738U/en not_active Expired - Fee Related
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Granted publication date: 20200731 |