CN209981435U - Microstrip band-pass filter of WLAN frequency channel - Google Patents
Microstrip band-pass filter of WLAN frequency channel Download PDFInfo
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- CN209981435U CN209981435U CN201921165787.1U CN201921165787U CN209981435U CN 209981435 U CN209981435 U CN 209981435U CN 201921165787 U CN201921165787 U CN 201921165787U CN 209981435 U CN209981435 U CN 209981435U
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Abstract
The utility model discloses a microstrip band pass filter of WLAN frequency channel, include: the upper layer of the substrate is provided with a microstrip line structure, and the lower layer of the substrate is covered with a metal floor; the microstrip line structure includes: a first resonance unit, a second resonance unit, and a third resonance unit; the first resonance unit comprises a first rectangular microstrip line frame and a second rectangular microstrip line frame, wherein a first notch and a second notch are respectively formed in the middle of one side of the first resonance unit, the second rectangular microstrip line frame is arranged in the first rectangular microstrip line frame at a certain interval, and the first rectangular microstrip line frame is connected with the second rectangular microstrip line frame through a microstrip connecting line penetrating through the second notch. The filter forms a new resonance frequency point by placing an open-circuit branch at the symmetrical axis of a first resonance unit and placing two short-circuit branches at two sides of the first resonance unit; a new transmission zero is generated at the stop band, so that the suppression capability outside the pass band is improved; the two parallel branches are used to replace the open-circuit branches, and the bending and meandering technology is performed, so that the size of the filter is reduced.
Description
Technical Field
The utility model belongs to the technical field of wireless communication and specifically relates to a microstrip band pass filter of WLAN frequency channel is related to.
Background
A filter is a device used to separate signals of different frequencies, and its main function is to suppress unwanted signals from passing through the filter, but only to allow wanted signals to pass through. In a microwave circuit system, the performance of a filter has a great influence on the performance index of the circuit, and therefore, how to design a filter with high performance is of great significance to the design of the microwave circuit system.
Band pass filters are a key device in electronic communication applications to select the desired signal of the system in a complex electromagnetic environment while filtering out unwanted interference and reducing the response of the system to unwanted signals. The WLAN wave band is a frequency band with the frequency of 2.4-2.48GHz and 5.15-5.35GHz and is used as a frequency band of wireless local area network transmission signals; at present, the filter applied to the WLAN wave band has not ideal out-of-band suppression and size, and cannot meet the requirements of some systems. Therefore, designing an ideal WLAN filter becomes an important point of design.
SUMMERY OF THE UTILITY MODEL
Utility model purpose: in order to overcome the not enough of background art, the utility model discloses a microstrip band pass filter of WLAN frequency channel.
The technical scheme is as follows: the utility model discloses a microstrip band pass filter of WLAN frequency channel, include: the metal floor board comprises a substrate, wherein the upper layer of the substrate is provided with a micro-strip line structure, and the lower layer of the substrate is covered with a metal floor board;
the microstrip line structure includes: a first resonance unit and a second resonance unit;
the first resonance unit comprises a first rectangular microstrip line frame and a second rectangular microstrip line frame, wherein a first notch and a second notch are respectively formed in the middle positions of one side of the first rectangular microstrip line frame and the second rectangular microstrip line frame, the second rectangular microstrip line frame is arranged in the first rectangular microstrip line frame and is spaced at a certain distance, meanwhile, the first notch and the second notch face oppositely, the first rectangular microstrip line frame and the second rectangular microstrip line frame are connected through a microstrip connecting line penetrating through the second notch, and the microstrip connecting line is positioned on a symmetry axis of the first resonance unit;
the second resonance unit is arranged outside the opposite side of the first notch of the first rectangular microstrip line frame in the direction and is of an I-shaped structure, the second resonance unit directly carries out signal input and signal output, grooves are respectively formed in symmetrical positions of the signal input side and the signal output side of the second resonance unit, the symmetrical positions of the signal input side and the signal output side of the second resonance unit respectively extend downwards to form a grounding microstrip line, and the end part of the grounding microstrip line is connected with a grounding metal through hole.
Wherein, the surface of the microstrip line structure is coated with a copper layer.
Furthermore, the grounding metal through hole sequentially penetrates through the microstrip line structure, the substrate and the metal floor.
Furthermore, the second resonance unit comprises a first microstrip line and a second microstrip line which are parallel to each other and connected through a third microstrip line to form an I-shaped structure, the first microstrip line is divided into an input microstrip line and an output microstrip line by the third microstrip line, and the grooves are respectively located on two sides of the third microstrip line.
The grounding microstrip lines are respectively positioned in the grooves and are symmetrical by taking the third microstrip line as a symmetry axis.
Further, a fourth microstrip line and a fifth microstrip line are symmetrically arranged below the second resonance unit and are respectively connected with the input microstrip line and the output microstrip line through microstrip lines with different characteristic impedances, a gap exists between the fourth microstrip line and the fifth microstrip line to form electric coupling, and the fourth microstrip line, the microstrip line with different characteristic impedances and used for being connected with the input microstrip line, the fifth microstrip line, and the microstrip line with different characteristic impedances and used for being connected with the output microstrip line are symmetrical by taking the gap between the fourth microstrip line and the fifth microstrip line as a symmetry axis.
Has the advantages that: compared with the prior art, the utility model has the advantages that: firstly, the filter forms a new resonance frequency point by placing an open-circuit branch at the symmetrical axis of a first resonance unit and placing two short-circuit branches at two sides of the first resonance unit; a new transmission zero is generated at the stop band, so that the suppression capability outside the pass band is improved; and then, two parallel branches are used for replacing open-circuit branches, a bending and bending technology is carried out, so that the size of the filter is reduced, the symmetrical positions of the signal input side and the signal output side of the second resonance unit respectively extend downwards to form grounding microstrip lines, the end parts of the grounding microstrip lines are connected with grounding metal through holes, magnetic coupling is formed in the transmission path, the electric coupling between a fourth microstrip line and a fifth microstrip line arranged below the second resonance unit forms another path, when signals are transmitted to an output port through the two paths, the phases of certain frequency signals are deviated, phase differences are generated, transmission zeros are formed, and the out-of-band rejection capability is improved.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a return loss and insertion loss diagram of the filter of the present invention.
Detailed Description
The technical solution of the present invention will be further explained with reference to the accompanying drawings and examples.
The microstrip bandpass filter of the WLAN band shown in fig. 1 includes: substrate 1, dimensions: 22mm 17.5mm 0.8mm (material is FR4), the upper layer of the substrate 1 is provided with a microstrip line structure, and the lower layer is covered with a metal floor (material is copper); and the surface of the microstrip line structure is coated with a copper layer.
The microstrip line structure includes: a first resonance unit 2 and a second resonance unit 3;
the first resonance unit 2 comprises a first rectangular microstrip frame 201 and a second rectangular microstrip frame 202, wherein a first notch 211 and a second notch 212 are respectively arranged at the middle position of one side of the first rectangular microstrip frame 201 and the second rectangular microstrip frame 202, the second rectangular microstrip frame 202 is arranged in the first rectangular microstrip frame 201 and is spaced at a certain distance, meanwhile, the first notch 211 and the second notch 212 face oppositely, the first rectangular microstrip frame 201 and the second rectangular microstrip frame 202 are connected through a microstrip connecting line 203 passing through the second notch 212, the microstrip connecting line 203 is positioned on the symmetry axis of the first resonance unit 2, in the first resonance unit 2, through electric coupling feeding, a branch (namely the microstrip connecting line 203) is added in the middle of a half-wavelength resonator, so that the two are connected with each other, and the structure generates two odd-even resonance frequencies, transmission zero can be generated at the stop band, and the suppression capability outside the pass band is improved.
The second resonance unit 3 is arranged outside the opposite side of the first notch 211 of the first rectangular microstrip line frame 201 and has an I-shaped structure, the second resonance unit 3 directly performs signal input and signal output, grooves 301 are respectively formed in symmetrical positions of the signal input side and the signal output side of the second resonance unit 3 and used for improving impedance fatigue, the symmetrical positions of the signal input side and the signal output side of the second resonance unit 3 respectively extend downwards to form a grounding microstrip line 302, the end part of the grounding microstrip line 302 is connected with a grounding metal through hole 303, and the grounding metal through hole 303 sequentially penetrates through the microstrip line structure, the substrate and the metal floor.
The second resonance unit 3 includes a first microstrip line 304 and a second microstrip line 305 that are parallel to each other, and are connected by a third microstrip line 306 to form an i-shaped structure, the length of the third microstrip line 306 is determined according to the required resonance frequency, the first microstrip line 304 is divided by the third microstrip line 306 into an input microstrip line 314 and an output microstrip line 324, the input microstrip line 314 and the output microstrip line 324 form axial symmetry through the third microstrip line 306, the grooves 301 are respectively located on both sides of the third microstrip line 306, the grounding microstrip line 302 is respectively located in the grooves 301, and the grounding microstrip line 302 and the grooves 301 on both sides of the third microstrip line 306 are both symmetrical in structure and position. The second resonator element 3, by direct feeding, generates a new resonance frequency and, at the same time, a new transmission zero. The input end and the output end are directly connected to form a transmission path, and two grounding branches (namely grounding microstrip lines 302) are respectively arranged on two sides of a symmetry axis on the input and output microstrip lines to form a magnetic coupling effect.
A fourth microstrip line 401 and a fifth microstrip line 402 are symmetrically arranged below the second resonance unit 3, the fourth microstrip line 401 and the fifth microstrip line 402 are arranged on two sides of the symmetry axis of the second resonance unit 3 and are respectively connected with the input microstrip line 314 and the output microstrip line 324 through microstrip lines with different characteristic impedances, a gap exists between the fourth microstrip line 401 and the fifth microstrip line 402 to form electric coupling, and a narrow gap, namely electric coupling, is formed at the symmetry axis of the filter through two step impedance resonators connected with the input end and the output end to form another transmission path; the signals through the two paths are superimposed at the output, and at this time, the electric coupling and the magnetic coupling cancel each other at some frequencies to form a transmission zero point.
As shown in fig. 2, the return loss (S11) and the insertion loss (S21) of the filter of the present invention are shown, and it can be seen from the figure that the passband frequency can well cover the WLAN (2.4-2.48GHz, 5.15-5.35GHz) frequency band, and the insertion loss meets the design requirement of the filter; and two transmission zeros are respectively arranged outside the two passbands, so that the suppression capability outside the passbands is improved, and the performance of the filter is improved.
Claims (6)
1. A microstrip bandpass filter for WLAN frequency bands, 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 metal floor is covered on the lower layer;
the microstrip line structure includes: a first resonance unit (2) and a second resonance unit (3);
the first resonance unit (2) comprises a first rectangular microstrip frame (201) and a second rectangular microstrip frame (202), wherein a first notch (211) and a second notch (212) are respectively formed in the middle of one side of the first rectangular microstrip frame (201) and the second rectangular microstrip frame (202), the second rectangular microstrip frame (202) is arranged in the first rectangular microstrip frame (201) at a certain interval, the first notch (211) and the second notch (212) face to each other, the first rectangular microstrip frame (201) and the second rectangular microstrip frame (202) are connected through a microstrip connecting line (203) penetrating through the second notch (212), and the microstrip connecting line (203) is located on a symmetry axis of the first resonance unit (2);
the second resonance unit (3) is arranged outside the opposite side of the first notch (211) of the first rectangular microstrip line frame (201) in the direction and is of an I-shaped structure, the second resonance unit (3) directly carries out signal input and signal output, grooves (301) are respectively formed in symmetrical positions of the signal input side and the signal output side of the second resonance unit (3), the symmetrical positions of the signal input side and the signal output side of the second resonance unit (3) respectively extend downwards to form a grounding microstrip line (302), and the end part of the second resonance unit is connected with a grounding metal through hole (303).
2. The microstrip band pass filter of WLAN frequency band according to claim 1 characterized by: and the surface of the microstrip line structure is coated with a copper layer.
3. The microstrip band pass filter of WLAN frequency band according to claim 1 characterized by: the grounding metal through hole (303) penetrates through the microstrip line structure, the substrate and the metal floor in sequence.
4. The microstrip band pass filter of WLAN frequency band according to claim 1 characterized by: the second resonance unit (3) comprises a first microstrip line (304) and a second microstrip line (305) which are parallel to each other, the first microstrip line and the second microstrip line are connected through a third microstrip line (306) to form an I-shaped structure, the first microstrip line (304) is divided into an input microstrip line (314) and an output microstrip line (324) by the third microstrip line (306), and the grooves (301) are respectively located on two sides of the third microstrip line (306).
5. The microstrip band pass filter of WLAN frequency band according to claim 4 characterized by: the grounding microstrip lines (302) are respectively positioned in the grooves (301).
6. The microstrip band pass filter of WLAN frequency band according to claim 4 characterized by: a fourth microstrip line (401) and a fifth microstrip line (402) are symmetrically arranged below the second resonance unit (3) and are respectively connected with the input microstrip line (314) and the output microstrip line (324) through microstrip lines with different characteristic impedances, and a gap exists between the fourth microstrip line (401) and the fifth microstrip line (402) to form electric coupling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921165787.1U CN209981435U (en) | 2019-07-24 | 2019-07-24 | Microstrip band-pass filter of WLAN frequency channel |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921165787.1U CN209981435U (en) | 2019-07-24 | 2019-07-24 | Microstrip band-pass filter of WLAN frequency channel |
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| CN209981435U true CN209981435U (en) | 2020-01-21 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110265757A (en) * | 2019-07-24 | 2019-09-20 | 南京信息工程大学 | A kind of microstrip bandpass filter of WLAN frequency range |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110265757A (en) * | 2019-07-24 | 2019-09-20 | 南京信息工程大学 | A kind of microstrip bandpass filter of WLAN frequency range |
| CN110265757B (en) * | 2019-07-24 | 2023-12-19 | 南京信息工程大学 | Microstrip band-pass filter of WLAN frequency band |
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