WO2018233227A1

WO2018233227A1 - Broadband bandpass filter loaded with three-branch coupled micro-strip line

Info

Publication number: WO2018233227A1
Application number: PCT/CN2017/114057
Authority: WO
Inventors: 曲美君; 邓力; 李书芳; 张贯京; 葛新科; 张红治
Original assignee: 深圳市景程信息科技有限公司
Priority date: 2017-06-23
Filing date: 2017-11-30
Publication date: 2018-12-27
Also published as: CN107394321A

Abstract

Provided is a broadband bandpass filter loaded with a three-branch coupled micro-strip line. The filter comprises two first micro-strip lines, two second micro-strip lines, two third micro-strip lines, two fourth micro-strip lines, two fifth micro-strip lines, two sixth micro-strip lines, two seventh micro-strip lines and two signal transmission ends which are all arranged on a surface of a dielectric plate. The broadband bandpass filter is bilaterally symmetrical about a first central axis, and the broadband bandpass filter is longitudinally symmetrical about a second central axis, wherein the first central axis is a connecting line between the middle points of upper and lower transverse frames of the broadband bandpass filter, and the second central axis is a connecting line between the middle points of left and right longitudinal frames of the broadband bandpass filter. The broadband bandpass filter in the present invention can realize a high selectivity for a passband signal, thereby introducing less noise and avoiding interference at a radio-frequency front end.

Description

Wideband bandpass filter for loading three-segment coupled microstrip lines

[0001] The present invention relates to the field of microwave communication technologies, and in particular, to a wideband bandpass filter for loading a three-segment coupled microstrip line.

Background technique

[0002] As a very important device in the RF front-end, the filter can filter out-of-band noise and improve the sensitivity of the circuit system. A microstrip filter is a device used to separate microwave signals of different frequencies. Its main function is to suppress unwanted signals so that they cannot pass through the filter and only pass the desired signal. In microwave circuit systems, the performance of the filter has a large impact on the performance of the circuit system. In general, the selective performance of the filter on the passband signal is an important indicator of influence, while the existing filter has a poor selectivity for the passband signal, which affects the performance of the entire communication system.

technical problem

[0003] It is an object of the present invention to provide a wideband bandpass filter for loading a three-segment coupled microstrip line, which is intended to solve the technical problem of poor passband signal selectivity in the prior art.

Problem solution

Technical solution

[0004] In order to achieve the above object, the present invention provides a broadband bandpass filter for loading a three-segment coupled microstrip line, comprising two first microstrip lines and two second microstrip lines disposed on a surface of the dielectric plate. Two third microstrip lines, two fourth microstrip lines, two fifth microstrip lines, two sixth microstrip lines, two seventh microstrip lines, and two signal transmission ends, the broadband The band pass filter is bilaterally symmetric about a first central axis, the wide band pass filter being vertically symmetrical about a second central axis, the first central axis being a midpoint of upper and lower horizontal borders of the broadband band pass filter The second central axis is a line connecting the midpoints of the left and right longitudinal frames of the broadband band pass filter, wherein:

[0005] The two first microstrip lines, two second microstrip lines, two third microstrip lines, two fourth microstrip lines, two fifth microstrip lines, and two signal transmission ends Each of the two sixth microstrip lines and the two seventh microstrip lines are parallel to the second central axis; [0006] One end of each of the first microstrip lines is connected to one signal output end, and the other end of each of the first microstrip lines and one end of a second microstrip line and one end of a third microstrip line Connecting, each fourth microstrip line is disposed in a gap formed between a second microstrip line and a third microstrip line, one end of each fourth microstrip line and a fifth microstrip line One end of the fifth microstrip line is connected to one end of the other fifth microstrip line, and one end of each sixth microstrip line is vertically connected to the connection position of the two fifth microstrip lines, each with The other end of the sixth microstrip line is connected to one end of a seventh microstrip line; and

[0007] Each of the second microstrip lines forms a three-joint coupling structure with a third microstrip line and a fourth microstrip line, and each sixth microstrip line and a seventh microstrip line form a double branch Match the load on the road.

[0008] Preferably, the wideband bandpass filter loading the three-segment coupled microstrip line includes two double-branch matching 负载 road loads and two three-branch coupling structures.

[0009] Preferably, the two signal transmission ends are respectively used for signal input and signal output, wherein one signal transmission end serves as a signal input end, and the other signal transmission end serves as a signal output end.

[0010] Preferably, the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, and the seventh microstrip line The signal transmission end is a metal copper piece with a strip structure.

[0011] Preferably, the length of the first microstrip line is 10 mm and the width is 1.66 mm, and the lengths of the second microstrip line and the third microstrip line are both 14.5 mm and the width is 0.21 mm. The length of the fourth microstrip line is 14.5 mm, the width is 0.12 mm, and the shortest distance between the fourth microstrip line and the second microstrip line is 0.18 mm, and the fourth microstrip line to the third microstrip The shortest distance between the lines is 0.18 mm, the length of the fifth microstrip line is 11.5 mm, the width is 2.88 mm, and the length of the sixth microstrip line is L4 = 12.9 mm, the width is 0.38 mm, and the seventh microstrip The length of the wire is 10.8 mm and the width is 2.78 mm, and the length of the signal transmission end is 10 mm and the width is 1.66 mm.

[0012] Preferably, the impedance of each of the first microstrip lines is 50 Ω, and each of the two, three, and four microstrip lines together form a three-branch coupling structure, and the odd-mode impedance of each three-joint coupling structure is 10 Ω. The model impedance is 8 Ω, the electrical length is 90 degrees, the impedance of each fifth microstrip line is 11 Ω, the impedance of each sixth microstrip line is 10 Ω, and the impedance of each seventh microstrip line is 12 Ω. .

[0013] Preferably, the dielectric plate is a PCB having a thickness of 0.762 mm and a relative dielectric constant of 3.66.

Advantageous effects of the invention

Beneficial effect [0014] Compared with the prior art, the wideband bandpass filter loading the three-segment coupled microstrip line of the present invention can be designed in the original two by designing two double-branched matching 幵-way loads and two three-branch coupling structures. Based on the filtering performance of the microstrip line, it achieves high selectivity to the passband signal, introduces less noise, and avoids interference to the RF front end.

Brief description of the drawing

DRAWINGS

1 is a schematic structural view of a preferred embodiment of a broadband bandpass filter for loading a three-branch coupled microstrip line of the present invention.

2 is a circuit schematic diagram of a preferred embodiment of a broadband bandpass filter for loading a three-segment coupled microstrip line of the present invention. [0016] FIG.

3 is a schematic diagram of S-parameter results simulated by an electromagnetic simulation software of a broadband bandpass filter loaded with a three-branch coupled microstrip line according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be further described in detail with reference to the preferred embodiments thereof. The following examples are illustrative of the invention, and the invention is not limited to the following examples.

1 to 2, FIG. 1 is a schematic structural view of a preferred embodiment of a broadband bandpass filter for loading a three-segment coupled microstrip line according to the present invention; FIG. 2 is a broadband diagram of the three-branch coupled microstrip line of the present invention. Circuit schematic of a preferred embodiment of a bandpass filter.

[0020] In the embodiment, the broadband bandpass filter 1 loading the three-segment coupled microstrip line includes two first microstrip lines 101 and two second microstrip lines 102 disposed on the surface of the dielectric plate 100. Two third microstrip lines 103, two fourth microstrip lines 104, two fifth microstrip lines 105, two sixth microstrip lines 106, two seventh microstrip lines 107, and two signal transmissions End Pl.

[0021] The wideband bandpass filter 1 loading the three-branch coupled microstrip line is bilaterally symmetric about a first central axis (ab line in FIG. 1) and is up and down with respect to a second central axis (the cd line in FIG. 1) Symmetrically, the first central axis is a line connecting the midpoints of the upper and lower lateral frames of the broadband bandpass filter 1 (ie, the line a-b in FIG. 1), and the second central axis is the A line connecting the midpoints of the left and right longitudinal frames of the broadband band pass filter 1 (i.e., line cd in Fig. 1), the first central axis and the second central axis are perpendicular to each other. [0022] Further, the two first microstrip lines 101, the two second microstrip lines 102, the two third microstrip lines 10 3, the two fourth microstrip lines 104, and the two fifth micros The strip line 105 and the two signal transmitting ends P1 are both parallel to the upper and lower horizontal borders, and the two sixth microstrip lines 106 and the two seventh microstrip lines 107 are connected to the broadband band pass filter 1 The two vertical borders are parallel.

[0023] It should be noted that the first central axis and the second central axis of the broadband bandpass filter 1 loaded with the three-branch coupled microstrip line are not components formed of metal, but are produced or designed. At this time, it is convenient for the user to connect the components on the broadband band pass filter 1 (for example, two first microstrip lines 101, two second microstrip lines 102, two third microstrip lines 103, two roots) The four microstrip lines 104, the two fifth microstrip lines 105, the two sixth microstrip lines 106, the two seventh microstrip lines 107, and the two signal transmission ends P1) are symmetric about the first central axis and are related to the first The two central axes are vertically symmetrical. When the wideband bandpass filter 1 is operating, the central axis does not participate in any operation such as signal filtering. In the embodiment, the first central axis and the second central axis are for convenience of describing the left and right and upper and lower symmetrical structures of the broadband band pass filter 1.

[0024] One end of each of the first microstrip lines 101 is connected to one signal output terminal P1, and the other end of each of the first microstrip lines 101 and one end of a second microstrip line 102 and a third micro One end of the strip line 103 is connected, wherein a gap is disposed between the second microstrip line 102 and the third microstrip line 103, and each of the fourth microstrip lines 104 is disposed on a second microstrip line 102 and a first In the gap formed between the three microstrip lines 103, one end of the fourth microstrip line 104 is connected to one end of a fifth microstrip line 105, and the other end of the fifth microstrip line 105 is connected to the other fifth. One end of the microstrip line 105 is connected, and each of the sixth microstrip lines 106 is vertically connected to the connection position of the two fifth microstrip lines 105, and the other end of the sixth microstrip line 106 is opposite to the seventh microstrip. One end of the strip line 107 is connected. The second microstrip line 102 and the third microstrip line 103 and the fourth microstrip line 104 form a three-node coupling structure 30, and each of the sixth microstrip lines 106 and a seventh microstrip Line 107 forms a double branch matching ramp load 20. As can be seen from Figures 1 and 2, the wideband bandpass filter 1 includes two double-branch-matching ramp loads 20 and two three-branch coupling structures 30.

[0025] The dielectric plate 100 is a PCB board, and the specific plate type is Roger RO4350B, wherein the relative dielectric constant is 3.66, and the plate thickness is 0.762 mm.

In this embodiment, the first microstrip line 101, the second microstrip line 102, the third microstrip line 103, the fourth microstrip line 104, the fifth microstrip line 105, and the sixth microstrip line 106 , the seventh microstrip line 107 and the signal transmission end P1 are Metal copper sheet with strip structure. The wideband bandpass filter for loading the three-segment coupled microstrip line of the present invention can change the length and width of the microstrip line to change the length of the microstrip line and the width of the microstrip line. The wideband bandpass filter 1 achieves a good match in the operating band.

[0027] In this embodiment, the operating band of the broadband bandpass filter 1 is in the range of 1.99 GHz to 4.72 GHz. The first microstrip line 101 and the second layer disposed on the surface of the dielectric board 100 are described by way of specific embodiments. The length and width of the microstrip line 102, the third microstrip line 103, the fourth microstrip line 104, the fifth microstrip line 105, the sixth microstrip line 106, the seventh microstrip line 107, and the signal transmission end P1.

[0028] Specifically, as shown in FIG. 1:

[0029] The length of the first microstrip line 101 is L = 10 mm, and the width of the first microstrip line 101 is W = 1.66 mm.

[0030] The second microstrip line 102 and the third microstrip line 103 have the same length, both of which are L1=14.5 mm, and the second microstrip line 10

2 and the third microstrip line have the same width, both of which are Wl=0.21mm.

[0031] The length of the fourth microstrip line 104 is L1=14.5 mm, the width of the fourth microstrip line is W2=0.12 mm, and the shortest distance between the fourth microstrip line 104 to the second microstrip line 102 is S1. =0.18 mm, the shortest distance between the fourth microstrip line 104 to the third microstrip line 103 is S1=0.18 mm.

[0032] The length of the fifth microstrip line 105 is L3 = 11.5 mm, and the width of the fifth microstrip line 105 is W3 = 2.88 mm.

[0033] The length of the sixth microstrip line 106 is L4 = 12.9 mm, and the width of the sixth microstrip line 106 is W4 = 0.38 mm.

[0034] The length of the seventh microstrip line 107 is L5 = 10.8 mm, and the width of the seventh microstrip line 107 is W5 = 2.78 mm.

[0035] The length of the signal transmission end PI is L0=10 mm, and the width of the signal transmission end PI is W0=1.66 mm.

[0036] It should be noted that the thickness of the metal copper plate disposed on the PCB board is generally um, so the present invention does not apply to the first microstrip line 101, the second microstrip line 102, and the third microstrip line 103, The thickness of the metal copper sheet of the length and width of the fourth microstrip line 104, the fifth microstrip line 105, the sixth microstrip line 106, the seventh microstrip line 107, and the signal transmission end P1 is limited, and does not affect the present invention. The characteristics of a wideband bandpass filter that loads a three-section coupled microstrip line. In addition, two signal transmission terminals P1 are respectively used for signal input and signal output, wherein one signal transmission terminal P1 serves as a signal input terminal and the other signal transmission terminal P1 serves as a signal output terminal. Further, the signal input end may be the signal transmission end P1 on the left side in FIG. 1 or the signal transmission end P1 on the right side; the signal output end may be the signal transmission end P1 on the left side in FIG. 1 or the signal transmission on the right side. End Pl. For example, if the signal transmission terminal P1 on the left side of FIG. 1 is used as the signal input terminal, the signal transmission terminal P1 on the right side of FIG. 1 serves as a signal output terminal, and the signal enters from the signal transmission terminal P1 on the left side, from the right. The edge of the signal transmission terminal PI output. If the left signal transmission terminal PI in Fig. 1 is used as the signal output terminal, the signal transmission terminal P1 on the right side of Fig. 1 serves as a signal input terminal, and the signal enters from the signal transmission terminal P1 on the right side and is output from the signal transmission terminal P1 on the left side.

[0037] In this embodiment, the impedance of each of the first microstrip lines is 50 Ω, and each of the two, three, and four microstrip lines together form a three-joint coupling structure, and the odd model of each three-joint coupling structure The impedance is 10Ω, the even mode impedance is 8Ω, the electrical length is 90 degrees, the impedance of each fifth microstrip line is 11Ω, the impedance of each sixth microstrip line is 10Ω, and the impedance of each seventh microstrip line It is 12Ω.

[0038] The wideband bandpass filter loaded with the three-branch coupled microstrip line of the present invention can be realized in a specific operating frequency band by designing two double-branch node matching circuit load 20 and two three-node coupling structures 30. The original microstrip line has filtering performance, high selectivity to the passband signal, and less noise is introduced to avoid interference to the RF front end.

Referring to FIG. 3, FIG. 3 is a schematic diagram of S-parameter results simulated by the electromagnetic simulation software of the broadband band-pass filter loaded with the three-branch coupled microstrip line of the present invention.

[0040] As can be seen from FIG. 3, the wideband bandpass filter 1 loaded with the three-segment coupled microstrip line has a working frequency band of 1.9 9 GHz to 4.72 GHz (the frequency range corresponding to the IS11I curve ordinate -10 dB in FIG. 3), There is a relative bandwidth of 81.37 < 3⁄4 [(4. 72-1.99) / (0.5 * (4.72 + 1.99))], that is, the structure using the present invention has a wider relative bandwidth. Similarly, in the operating frequency band of 1.28 GHz, the reflection coefficient (ie IS11 I in Figure 3) can reach -67 dB, the frequency in the operating band is 6.5 GHz, and the transmission coefficient (ie IS21I in Figure 3) is -95 dB, as can be seen from Fig. 3, the passband signal of the wideband bandpass filter 1 has high selectivity. It can be seen that the wideband bandpass filter of the three-segment coupled microstrip line of the present invention has high selectivity to the passband signal and a wider relative bandwidth, introducing less noise and avoiding interference to the radio frequency front end.

[0041] The wideband bandpass filter loading the three-segment coupled microstrip line of the present invention includes two double-branch node matching loop loads 20 and two three-branch coupling structures 30, so that the original microstrip line has the basis of filtering performance. It has a high band pass selectivity.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the present invention and the contents of the drawings may be directly or indirectly applied to other related The technical field is equally included in the scope of patent protection of the present invention. Industrial applicability

Compared with the prior art, the wideband bandpass filter loaded with the three-segment coupled microstrip line of the present invention can be designed in the original microstrip line by designing two double-branched matching 幵-way loads and two three-branch coupling structures. Based on the filtering performance, it achieves high selectivity to the passband signal, introduces less noise, and avoids interference to the RF front end.

Claims

Claim

[Claim 1] A broadband bandpass filter for loading a three-branch coupled microstrip line, comprising: two first microstrip lines, two second microstrip lines, and two disposed on a surface of a dielectric plate a third microstrip line, two fourth microstrip lines, two fifth microstrip lines, two sixth microstrip lines, two seventh microstrip lines, and two signal transmission ends, the broadband band pass filtering The device is bilaterally symmetric about a first central axis, the broadband bandpass filter being vertically symmetric about a second central axis, the first central axis being a line connecting the midpoints of the upper and lower lateral borders of the broadband bandpass filter The second central axis is a line connecting the midpoints of the left and right longitudinal frames of the broadband band pass filter, wherein: the two first microstrip lines, the two second microstrip lines, and the two The third microstrip line, the two fourth microstrip lines, the two fifth microstrip lines, and the two signal transmission ends are all parallel to the first central axis, and the two sixth microstrip lines and two The seven microstrip lines are all parallel to the second central axis; one of each of the first microstrip lines The end is connected to a signal output end, and the other end of each of the first microstrip lines is connected to one end of a second microstrip line and one end of a third microstrip line, and each fourth microstrip line is disposed on In a gap formed between a second microstrip line and a third microstrip line, one end of each fourth microstrip line is connected to one end of a fifth microstrip line, the fifth microstrip line The other end is connected to one end of another fifth microstrip line, and one end of each sixth microstrip line is vertically connected to the connection position of the two fifth microstrip lines, and the other end of each of the sixth microstrip lines and one One end of the seventh microstrip line is connected; and each second microstrip line forms a three-segment coupling structure with a third microstrip line and a fourth microstrip line, and each sixth microstrip line and one The seven microstrip lines form a double-branched matching 幵 load.

[Claim 2] The wideband bandpass filter for loading a three-branch coupled microstrip line according to claim 1, wherein the wideband bandpass filter that loads the three-segment coupled microstrip line includes two double-branched sections Match the crotch load and two three-node coupling structures.

[Claim 3] The wideband bandpass filter of the three-segment coupled microstrip line according to claim 1, wherein the two signal transmission ends are used for signal input and signal output, respectively, One signal transmission end serves as a signal input end, and the other signal transmission end serves as a signal output end.

[Claim 4] The wideband bandpass filter for loading a three-branch coupled microstrip line according to claim 1, The first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, the seventh microstrip line, and the signal transmission end Metal copper sheets with strip structure.

[Claim 5] The wideband bandpass filter for loading a three-branch coupled microstrip line according to claim 1, wherein the first microstrip line has a length of 10 mm and a width of 1.66 mm. The lengths of the second microstrip line and the third microstrip line are both 14.5 mm and the width is 0.21 mm, and the length of the fourth microstrip line is 14.5 mm and the width is 0.12 mm, and the fourth microstrip line is The shortest distance between the two microstrip lines is 0.18 mm, the shortest distance between the fourth microstrip line to the third microstrip line is 0.18 mm, and the length of the fifth microstrip line is 11.5 mm and the width is 2.8 8 mm. The length of the sixth microstrip line is L4=12.9 mm, the width is 0.38 mm, the length of the seventh microstrip line is 10.8 mm, the width is 2.78 mm, and the length of the signal transmission end is 10 mm and the width is 1.66 mm.

[Claim 6] The broadband bandpass filter for loading a three-branch coupled microstrip line according to claim 1, wherein each of the first microstrip lines has an impedance of 50 Ω, each of two, three, and four The microstrip lines together form a three-joint coupling structure. The odd-mode impedance of each three-joint coupling structure is 10Ω, the even-mode impedance is 8Ω, the electrical length is 90 degrees, and the impedance of each fifth microstrip line is 11Ω. The impedance of each sixth microstrip line is 10Ω, and the impedance of each seventh microstrip line is 12Ω.

The broadband band-pass filter for loading a three-branch coupled microstrip line according to any one of claims 1 to 6, wherein the dielectric plate is a plate thickness of 0.762 mm and is relatively A PCB with an electrical constant of 3.66.