Topological structure, filter and communication equipment

Abstract

The embodiment of the utility model relates to the field of communication equipment, in particular to a topological structure and a filter. Comprising an input end, an output end, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, a seventh microstrip line, an eighth microstrip line, a ninth microstrip line, a tenth microstrip line, an eleventh microstrip line, a twelfth microstrip line, a thirteenth microstrip line and a fourteenth microstrip line. A first short-circuit branch, a second short-circuit branch, a third short-circuit branch, a fourth short-circuit branch, a first open-circuit branch and a second open-circuit branch. The band-pass filter based on the topological structure not only has the notch characteristic, but also has the advantages of high selectivity and miniaturization.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of communication equipment, and in particular to a topological structure, a filter and a communication equipment. Background Art

[0002] A broadband bandpass filter with a notch feature is one of the key components of modern wireless communication equipment. It can suppress in-band interference and transmit signals at high speed. It can be understood that a broadband bandpass filter with a notch feature is a broadband bandpass filter with a notch feature. However, the broadband bandpass filter with a notch feature currently not only has poor selectivity, but also has a non-compact structure, which greatly limits the use of broadband bandpass filters in wireless communication systems. Utility Model Content

[0003] The embodiment of the utility model provides a topological structure, which not only has the trap wave characteristic, but also has the advantages of high selectivity and miniaturization.

[0004] In order to solve the above technical problems, a technical solution adopted by the utility model is: to provide a topological structure, including an input end, an output end, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, a seventh microstrip line, an eighth microstrip line, a ninth microstrip line, a tenth microstrip line, an eleventh microstrip line, a twelfth microstrip line, a thirteenth microstrip line, a fourteenth microstrip line, a first short-circuit branch, a second short-circuit branch, a third short-circuit branch, a fourth short-circuit branch, a first open-circuit branch and a second open-circuit branch, one end of the second parallel line is connected to one end of the first parallel line, one end of the third microstrip line and one end of the ninth microstrip line, the other end of the second parallel line is connected to one end of the eighth microstrip line, one end of the third parallel line and one end of the fourteenth microstrip line, the input end is connected to the first microstrip line One end of the output end is connected to the other end of the first parallel line, the first open-circuit branch is connected to the other end of the first microstrip line, the output end is connected to the other end of the first parallel line and one end of the second microstrip line, the second open-circuit branch is connected to the other end of the second microstrip line, the other end of the third microstrip line, the fourth microstrip line, the fifth microstrip line, the first short-circuit branch, the second short-circuit branch, the sixth microstrip line, the seventh microstrip line and the other end of the eighth microstrip line are connected in sequence, the first short-circuit branch and the second short-circuit branch are grounded, the other ends of the ninth microstrip line, the tenth microstrip line, the eleventh microstrip line, the third short-circuit branch, the fourth short-circuit branch, the twelfth microstrip line, the thirteenth microstrip line and the fourteenth microstrip line are connected in sequence, and the third short-circuit branch and the fourth short-circuit branch are grounded.

[0005] Optionally, the first parallel line, the second parallel line, the third parallel line, the first microstrip line, the second microstrip line, the fourth microstrip line, the seventh microstrip line, the tenth microstrip line, the thirteenth microstrip line, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch and the fourth short-circuit branch are parallel to each other and perpendicular to the third microstrip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line, the ninth microstrip line, the eleventh microstrip line, the twelfth microstrip line, the fourteenth microstrip line, the first open branch and the second open branch.

[0006] Optionally, the first parallel lines include a first transmission line and a second transmission line arranged in parallel, the first transmission line is connected to the input end and one end of the first microstrip line, and the second transmission line is connected to one end of the third microstrip line, one end of the ninth microstrip line and one end of the second parallel line.

[0007] Optionally, the second parallel lines include a third transmission line and a fourth transmission line arranged in parallel, the third transmission line is connected to the other end of the second transmission line, one end of the third microstrip line and one end of the ninth microstrip line, and the fourth transmission line is connected to one end of the third parallel line, one end of the eighth microstrip line and one end of the fourteenth microstrip line.

[0008] Optionally, the third parallel lines include a fifth transmission line and a sixth transmission line arranged in parallel, the fifth transmission line is connected to the fourth transmission line, one end of the eighth microstrip line and one end of the fourteenth microstrip line, and the sixth transmission line is connected to the output end and one end of the second microstrip line.

[0009] Optionally, the electrical length of the first parallel line, the electrical length of the second parallel line, and the electrical length of the third parallel line are equal, and are all equal to a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

[0010] Optionally, the electrical length of the first microstrip line is equal to the electrical length of the second microstrip line, the electrical length of the first open branch is equal to the electrical length of the second open branch, and the sum of the electrical length of the first microstrip line and the electrical length of the first open branch is a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure, and is also a quarter wavelength corresponding to the notch center frequency of the bandpass filter designed based on the topological structure.

[0011] Optionally, the sum of the electrical length of the third microstrip line, the electrical length of the fourth microstrip line, the electrical length of the fifth microstrip line and the electrical length of the first short-circuit branch is greater than a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

[0012] The present application also provides a filter embodiment, and the filter is designed based on the above-mentioned topological structure.

[0013] In order to solve the above technical problem, a technical solution adopted by the present utility model is: to provide a communication device, including the above filter.

[0014] The beneficial effect of the embodiments of the present application is that: through the above method, the broadband bandpass filter designed based on the topological structure not only has the notch characteristic, but also has the advantages of high selectivity and miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of a topological structure provided by an embodiment of the utility model;

[0017] Figure 2 It is a schematic diagram of an odd-mode form of a topological structure provided by an embodiment of the utility model;

[0018] Figure 3 It is a schematic diagram of an even-mode form of a topological structure provided by an embodiment of the utility model;

[0019] Figure 4 The embodiment of the utility model provides a filter layout based on topological structure design;

[0020] Figure 5 It is an S parameter simulation diagram of the filter provided by the embodiment of the utility model.

[0021] Reference numerals:

[0022] 10. Input terminal; 20. Output terminal; 31. First parallel line; 32. Second parallel line; 33. Third parallel line; 41. First microstrip line; 42. Second microstrip line; 43. Third microstrip line; 44. Fourth microstrip line; 45. Fifth microstrip line; 46. Sixth microstrip line; 47. Seventh microstrip line; 48. Eighth microstrip line; 49. Ninth microstrip line; 50. Tenth microstrip line; 51. Eleventh microstrip line; 52. Twelfth microstrip line; 53. Thirteenth microstrip line; 54. Fourteenth microstrip line; 61. First short-circuit branch; 62. Second short-circuit branch; 63. Third short-circuit branch; 64. Fourth short-circuit branch; 71. First open-circuit branch; 72. Second open-circuit branch; 80. Odd-mode transmission line; 90. Even-mode transmission line. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the utility model, the utility model is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in this specification are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0025] See also Figure 1The topological structure includes an input terminal 10, an output terminal 20, a first parallel line 31, a second parallel line 32, a third parallel line 33, a first microstrip line 41, a second microstrip line 42, a third microstrip line 43, a fourth microstrip line 44, a fifth microstrip line 45, a sixth microstrip line 46, a seventh microstrip line 47, an eighth microstrip line 48, a ninth microstrip line 49, a tenth microstrip line 50, an eleventh microstrip line 51, a twelfth microstrip line 52, a thirteenth microstrip line 53, a fourteenth microstrip line strip line 54, a first short-circuit branch 61, a second short-circuit branch 62, a third short-circuit branch 63, a fourth short-circuit branch 64, a first open-circuit branch 71 and a second open-circuit branch 72, one end of the second parallel line 32 is connected to one end of the first parallel line 31, one end of the third microstrip line 43 and one end of the ninth microstrip line 49, the other end of the second parallel line 32 is connected to one end of the eighth microstrip line 48, one end of the third parallel line 33 and one end of the fourteenth microstrip line 54, The input end 10 is connected to one end of the first microstrip line 41 and the other end of the first parallel line 31, the first open-circuit branch 71 is connected to the other end of the first microstrip line 41, the output end 20 is connected to the other end of the first parallel line 31 and one end of the second microstrip line 42, the second open-circuit branch 72 is connected to the other end of the second microstrip line 42, the other end of the third microstrip line 43, the fourth microstrip line 44, the fifth microstrip line 45, the first short-circuit branch 61, and the second short-circuit branch 62 The other ends of the sixth microstrip line 46, the seventh microstrip line 47 and the eighth microstrip line 48 are connected in sequence, the first short-circuit branch 61 and the second short-circuit branch 62 are grounded, the other ends of the ninth microstrip line 49, the tenth microstrip line 50, the eleventh microstrip line 51, the third short-circuit branch 63, the fourth short-circuit branch 64, the twelfth microstrip line 52, the thirteenth microstrip line 53 and the fourteenth microstrip line 54 are connected in sequence, and the third short-circuit branch 63 and the fourth short-circuit branch 64 are grounded. The filter designed based on the above topological structure not only has the trap feature, but also has the advantages of high selectivity and miniaturization.

[0026] The third microstrip line 43, the fourth microstrip line 44, the fifth microstrip line 45, the first short-circuit branch 61, the second short-circuit branch 62, the sixth microstrip line 46, the seventh microstrip line 47 and the eighth microstrip line 48 are symmetrically arranged with the ninth microstrip line 49, the tenth microstrip line 50, the eleventh microstrip line 51, the third short-circuit branch 63, the fourth short-circuit branch 64, the twelfth microstrip line 52, the thirteenth microstrip line 53 and the fourteenth microstrip line 54 about the first parallel line 31, the second parallel line 32 or the third parallel line 33.

[0027] The first parallel line 31, the second parallel line 32, the third parallel line 33, the first microstrip line 41, the second microstrip line 42, the fourth microstrip line 44, the seventh microstrip line 47, the tenth microstrip line 50, the thirteenth microstrip line 53, the first short-circuit branch 61, the second short-circuit branch 62, the third short-circuit branch 63 and the fourth short-circuit branch 64 are parallel to each other and are perpendicular to the third microstrip line 43, the fifth microstrip line 45, the sixth microstrip line 46, the eighth microstrip line 48, the ninth microstrip line 49, the eleventh microstrip line 51, the twelfth microstrip line 52, the fourteenth microstrip line 54, the first open-circuit branch 71 and the second open-circuit branch 72.

[0028] The first parallel line 31, see Figure 1 Combination Figure 4 The first parallel line 31 includes a first transmission line and a second transmission line arranged in parallel. The first transmission line is connected to the input terminal 10 and one end of the first microstrip line 41, and the second transmission line is connected to one end of the third microstrip line 43, one end of the ninth microstrip line 49, and one end of the second parallel line 32.

[0029] The second parallel line 32, see Figure 1 Combination Figure 4 The second parallel line 32 includes a third transmission line and a fourth transmission line arranged in parallel. The third transmission line is connected to the other end of the second transmission line, one end of the third microstrip line 43 and one end of the ninth microstrip line 49, and the fourth transmission line is connected to one end of the third parallel line 33, one end of the eighth microstrip line 48 and one end of the fourteenth microstrip line 54.

[0030] The third parallel line 33 mentioned above, please refer to Figure 1 Combination Figure 4 The third parallel line 33 includes a fifth transmission line and a sixth transmission line arranged in parallel, the fifth transmission line is connected to the fourth transmission line, one end of the eighth microstrip line 48 and one end of the fourteenth microstrip line 54, and the sixth transmission line is connected to the output end 20 and one end of the second microstrip line 42.

[0031] The electrical lengths of the first parallel line 31 , the second parallel line 32 , and the third parallel line 33 are equal, and are all equal to a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

[0032] The electrical length of the first microstrip line 41 is equal to the electrical length of the second microstrip line 42, the electrical length of the first open branch 71 is equal to the electrical length of the second open branch 72, and the sum of the electrical length of the first microstrip line 41 and the electrical length of the first open branch 71 is a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure, and is also a quarter wavelength corresponding to the notch center frequency of the bandpass filter designed based on the topological structure.

[0033] The electrical length of the third microstrip line 43 is equal to the electrical length of the fourteenth microstrip line 54, the electrical length of the eighth microstrip line 48 is equal to the electrical length of the ninth microstrip line 49, the electrical length of the fourth microstrip line 44, the electrical length of the seventh microstrip line 47, the electrical length of the tenth microstrip line 50 and the electrical length of the thirteenth microstrip line 53 are equal, the electrical length of the fifth microstrip line 45, the electrical length of the sixth microstrip line 46, the electrical length of the eleventh microstrip line 51 and the electrical length of the twelfth microstrip line 52 are equal, the electrical length of the first short-circuit branch 61 is equal to the electrical length of the fourth short-circuit branch 62. The electrical lengths of the short-circuit branches 64 are equal, the electrical lengths of the second short-circuit branches 62 and the third branches are equal, the sum of the electrical lengths of the third microstrip line 43 and the first microstrip line 41 is equal to the sum of the electrical lengths of the eighth microstrip line 48 and the second microstrip line 42, and the sum of the electrical lengths of the third microstrip line 43, the fourth microstrip line 44, the fifth microstrip line 45, and the first short-circuit branch 61 is greater than a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

[0034] The odd-mode characteristic impedance of the first parallel line 31 is equal to the odd-mode characteristic impedance of the third parallel line 33, the even-mode characteristic impedance of the first parallel line 31 is equal to the even-mode characteristic impedance of the third parallel line 33, the characteristic impedance of the first microstrip line 41, the characteristic impedance of the second microstrip line 42, the characteristic impedance of the first open-circuit branch 71, and the characteristic impedance of the second open-circuit branch 72 are equal, the characteristic impedance of the third microstrip line 43, the characteristic impedance of the fourth microstrip line 44, the characteristic impedance of the fifth microstrip line 45, the characteristic impedance of the sixth microstrip line 46, the characteristic impedance of the seventh microstrip line 47, the characteristic impedance of the eighth microstrip line 48, the characteristic impedance of the ninth microstrip line 49, the characteristic impedance of the tenth microstrip line 50, the characteristic impedance of the eleventh microstrip line 51, the characteristic impedance of the twelfth microstrip line 52, the characteristic impedance of the thirteenth microstrip line 53, the characteristic impedance of the fourteenth microstrip line 54, the characteristic impedance of the first short-circuit branch 61, the characteristic impedance of the second short-circuit branch 62, the characteristic impedance of the third short-circuit branch 63, and the characteristic impedance of the fourth short-circuit branch 64 are equal.

[0035] The utility model provides a filter embodiment, and the filter is designed based on the above topological structure.

[0036] For the convenience of description, the electrical length of the first parallel line 31, the electrical length of the second parallel line 32 and the electrical length of the third parallel line 33 are all set to θ, the electrical length of the first microstrip line 41 and the electrical length of the first open branch 71 are expressed as θ1+θ2, the electrical length of the third microstrip line 43 and the electrical length of the fourteenth microstrip line 54 are both set to θ3, the electrical length of the eighth microstrip line 48 and the electrical length of the ninth microstrip line 49 are both set to θ4, the electrical length of the fourth microstrip line 44, the electrical length of the seventh microstrip line 47 and the electrical length of the tenth microstrip line 48 are both set to θ6, and the electrical length of the fourth microstrip line 44, the electrical length of the seventh microstrip line 47 and the electrical length of the tenth microstrip line 48 are both set to θ7. The electrical length of the line 50 and the electrical length of the thirteenth microstrip line 53 are both set to θ5, the electrical length of the fifth microstrip line 45, the electrical length of the sixth microstrip line 46, the electrical length of the eleventh microstrip line 51 and the electrical length of the twelfth microstrip line 52 are all set to θ6, the electrical length of the first short-circuit branch 61 and the electrical length of the fourth short-circuit branch 64 are both set to θ7, the electrical length of the second short-circuit branch 62 and the electrical length of the third branch are both set to θ8, the odd-mode characteristic impedance of the first parallel line 31 and the odd-mode characteristic impedance of the third parallel line 33 are both set to Z o1 , the even-mode characteristic impedance of the first parallel line 31 and the even-mode characteristic impedance of the third parallel line 33 are both set to Z e1 , the odd-mode characteristic impedance of the second parallel line 32 is set to Z O2 , the even-mode characteristic impedance of the second parallel line 32 is set to Z e2 , the characteristic impedance of the first microstrip line 41, the characteristic impedance of the second microstrip line 42, the characteristic impedance of the first open-circuit branch 71 and the characteristic impedance of the second open-circuit branch 72 are all set to Z1, the characteristic impedance of the third microstrip line 43, the characteristic impedance of the fourth microstrip line 44, the characteristic impedance of the fifth microstrip line 45, the characteristic impedance of the sixth microstrip line 46, the characteristic impedance of the seventh microstrip line 47, the characteristic impedance of the eighth microstrip line 48, the characteristic impedance of the ninth microstrip line 49, the characteristic impedance of the tenth microstrip line 50, the characteristic impedance of the eleventh microstrip line 51, the characteristic impedance of the twelfth microstrip line 52, the characteristic impedance of the thirteenth microstrip line 53, the characteristic impedance of the fourteenth microstrip line 54, the characteristic impedance of the first short-circuit branch 61, the characteristic impedance of the second short-circuit branch 62, the characteristic impedance of the third short-circuit branch 63 and the characteristic impedance of the fourth short-circuit branch 64 are all set to Z2.

[0037] See also Figure 2-Figure 3, the above topological structure can be equivalent to a symmetrical structure, therefore, the transmission poles of the topological structure can be obtained by odd-even mode analysis. In order to simplify the calculation process, it is first assumed that the sum of the electrical length of the third microstrip line 43, the electrical length of the fourth microstrip line 44, the electrical length of the fifth microstrip line 45, and the electrical length of the first short-circuit branch 61 is equal to the quarter wavelength corresponding to the center frequency of the above filter, and the electrical length of the odd-mode transmission line 80 is equal to the electrical length of the second parallel line 32, and the characteristic impedance of the odd-mode transmission line 80 is equal to the odd-mode characteristic impedance of the second parallel line 32. The calculation and analysis after the topological structure is simplified are as follows:

[0038]

[0039] When Y ino = 0, it can be concluded that the topology has four transmission poles. When f0 is the center frequency of the filter, the frequencies corresponding to the four odd-mode transmission poles are:

[0040]

[0041]

[0042] in:

[0043] Δ o1 =2Z2(Z e1 -Z o1 ) 2

[0044] Δ o2 =4Z2Z o2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +Z o2 (Z e1 -Z o1 ) 2

[0045] +4Z1Z2(Z e1 +Z o1 )

[0046] Δ o3 =4Z o1 Z e1 Z o2 +Z1Z o2

[0047] In the even-mode form of this topological structure, the electrical length of the even-mode transmission line 90 is equal to the electrical length of the second parallel line 32 , and the characteristic impedance of the even-mode transmission line 90 is equal to the even-mode characteristic impedance of the second parallel line 32 .

[0048]

[0049] When Y ine = 0, it can be concluded that the topology has four transmission poles. When f0 is the center frequency of the filter, the frequencies corresponding to the four even-mode transmission poles are:

[0050]

[0051] in:

[0052] Δ e1 =2Z2(Z e1 -Z o1 ) 2

[0053] Δ e2 =4Z2Z e2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +Z e2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )

[0054] Δ e3 =4Z o1 Z e1 Z e2 +Z1Z e2

[0055] The transmission zero point of the above topological structure can be calculated by the following method: multiply the ABCD matrices of the cascaded resonators constituting the topological structure in sequence to obtain the ABCD matrix corresponding to the topological structure; and convert the ABCD matrix of the topological structure into the corresponding S matrix. 21 When |=0, it can be concluded that this topology has three transmission zeros, and the frequencies corresponding to the three transmission zeros are:

[0056] f z1 =0

[0057] f z2 =f0

[0058] f z3 =2f0

[0059] From the above analysis, it can be seen that when the sum of the electrical lengths of the second microstrip line 42, the third microstrip line 43, and the first short-circuit branch 61 is equal to a quarter wavelength corresponding to the center frequency of the broadband bandpass filter, the topological structure has four odd-mode transmission poles, four even-mode transmission poles, and three transmission zeros. Returning to this topological structure, when the sum of the electrical lengths of the second microstrip line 42, the third microstrip line 43, and the first short-circuit branch 61 is appropriately increased, three additional transmission zeros (f z4 , f z5 , f z6 ), but the number of original zeros and poles remains unchanged. And no matter how the parameter Z is changed o1 , Z e1 , Z o2 , Z e2 , the values ​​of Z1 and Z2, and the relative positions of the transmission zeros and poles, i.e., f z1 <f z4 <f ep1 <f op1 <f op2 <f ep2 <f z2 <f ep3 <f op3 <f op4 <f ep4 <f z5 <f z3 <f z6 , will not change. Therefore, based on this topology, a broadband bandpass filter with notch characteristics can be designed, and there are eight transmission poles in the passband to ensure the flatness of the bandpass filter, five transmission zeros in the stopband to ensure high selectivity and high isolation, and one transmission zero in the passband to form the required notch.

[0060] For the specific structure and function of the topological structure, please refer to the above embodiments, which will not be described in detail here.

[0061] In order to verify the concept of the filter of the embodiment of the utility model, the following physical simulation experiment is carried out:

[0062] The actual design of the filter in the embodiment of the utility model is on a circuit board, the size of the circuit board is 35mm×14.9mm, the dielectric constant of the circuit board is 3.38, the dielectric loss of the circuit board is 0.0022, and the thickness of the circuit board is 0.813mm. The design parameters of the filter are: OP =9.8mm,s OP =0.1mm, w OP =0.25mm, l IP =9.8,s IP =0.1mm, W IP=0.2mm, l1=8.9mm, l2=2.3mm, l3=4.8mm, l4=5.1mm, l5=5.4mm, l6=0.9mm, l7=1.8mm, l8=1.5mm, W1=0.4mm, W2=0.9mm, S1=0.1mm. Among them, l OP is the physical length of the first parallel line 31 or the physical length of the third parallel line 33, S OP is the distance between the first transmission line and the second transmission line, or the distance between the fifth transmission line and the sixth transmission line, W OP is the physical width of the first transmission line, the physical width of the second transmission line, the physical width of the fifth transmission line, or the physical width of the sixth transmission line, l IP is the physical length of the second parallel line 32, S IP The spacing between the third transmission line and the fourth transmission line, w IP is the physical width of the third transmission line or the physical width of the fourth transmission line, l1 is the physical length of the first microstrip line 41 or the physical length of the second microstrip line 42, l2 is the physical length of the first open-circuit branch 71 or the physical length of the second open-circuit branch 72, l3 is the physical length of the third microstrip line 43 or the physical length of the fourteenth microstrip line 54, l4 is the physical length of the eighth microstrip line 48 or the physical length of the ninth microstrip line 49, l5 is the physical length of the fourth microstrip line 44 or the physical length of the seventh microstrip line 47 or the physical length of the tenth microstrip line 50 or the physical length of the thirteenth microstrip line 53, l6 is the physical length of the fifth microstrip line 45 or the physical length of the sixth microstrip line 46 or the physical length of the eleventh microstrip line 51 or the physical length of the twelfth microstrip line 52, l7 is the physical length of the first short-circuit branch 61 or the physical length of the fourth short-circuit branch 64, l8 is the physical length of the second short-circuit branch 62 or the physical length of the third short-circuit branch 63, W1 is the physical width of the first microstrip line 41 or the physical width of the second microstrip line 42 or the physical width of the first open-circuit branch 71 or the width of the second open-circuit branch 72, W2 is the physical width of the third microstrip line 43 or the physical width of the fourth microstrip line 44 or the physical width of the fifth microstrip line 45 or the physical width of the sixth microstrip line 46 or the physical width of the seventh microstrip line 47 or the physical width of the eighth microstrip line 48 or the physical width of the ninth microstrip line 49 or the physical width of the tenth microstrip line 50 or the physical width of the eleventh microstrip line 51 or the physical width of the twelfth microstrip line 52 or the physical width of the thirteenth microstrip line 53 or the physical width of the fourteenth microstrip line 54 or the physical width of the first short-circuit branch 61 or the physical width of the second short-circuit branch 62 or the physical width of the third short-circuit branch 63 or the physical width of the fourth short-circuit branch 64.

[0063] The simulation results of the utility model filter are as follows Figure 5As shown in the figure, the passband range of the filter with a reflection coefficient better than -10dB is 2.42GHz to 7.24GHz, the center frequency is 4.83GHz, the absolute bandwidth is 4.82GHz, and the relative bandwidth is 99.8%. In addition, there are six transmission poles in the passband of the filter, located at 2.49GHz, 2.96GHz, 4.08GHz, 5.06GHz, 6.26GHz and 7.08GHz, respectively. These six transmission poles ensure the flatness of the passband; there is also a transmission zero point in the passband of the filter, located at 4.76GHz, to form the required notch, and the isolation at the notch center frequency is 28.7dB, showing good isolation. There are four transmission zero points in the stopband, located at 0GHz, 1.44GHz, 7.54GHz and 10.45GHz, respectively. These four transmission zero points ensure the high selectivity of the filter and high isolation in the stopband.

[0064] The utility model also provides a communication device embodiment, and the communication device includes the above-mentioned filter.

[0065] In the embodiment of the present application, a broadband bandpass filter with notch characteristics can be designed through the above topological structure, and the filter has the advantages of high selectivity and miniaturization.

[0066] It should be noted that the preferred embodiments of the utility model are given in the specification and drawings of the utility model, but the utility model can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional restrictions on the content of the utility model. The purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the utility model; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the utility model.

Claims

1. A topological structure, characterized in that: include: an input end, an output end, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, a seventh microstrip line, an eighth microstrip line, a ninth microstrip line, a tenth microstrip line, an eleventh microstrip line, a twelfth microstrip line, a thirteenth microstrip line, a fourteenth microstrip line, a first short-circuit branch, a second short-circuit branch, a third short-circuit branch, a fourth short-circuit branch, a first open-circuit branch and a second open-circuit branch; one end of the second parallel line is connected to one end of the first parallel line, one end of the third microstrip line and one end of the ninth microstrip line; the other end of the second parallel line is connected to one end of the eighth microstrip line, one end of the third parallel line and one end of the fourteenth microstrip line; the input end is connected to one end of the first microstrip line and the other end of the first parallel line; The first open-circuit branch is connected to the other end of the first microstrip line, the output end is connected to the other end of the first parallel line and one end of the second microstrip line, the second open-circuit branch is connected to the other end of the second microstrip line, the other end of the third microstrip line, the fourth microstrip line, the fifth microstrip line, the first short-circuit branch, the second short-circuit branch, the sixth microstrip line, the seventh microstrip line and the other end of the eighth microstrip line are connected in sequence, the first short-circuit branch and the second short-circuit branch are grounded, the other ends of the ninth microstrip line, the tenth microstrip line, the eleventh microstrip line, the third short-circuit branch, the fourth short-circuit branch, the twelfth microstrip line, the thirteenth microstrip line and the fourteenth microstrip line are connected in sequence, and the third short-circuit branch and the fourth short-circuit branch are grounded.

2. The topological structure according to claim 1, characterized in that: The first parallel line, the second parallel line, the third parallel line, the first microstrip line, the second microstrip line, the fourth microstrip line, the seventh microstrip line, the tenth microstrip line, the thirteenth microstrip line, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch and the fourth short-circuit branch are parallel to each other and perpendicular to the third microstrip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line, the ninth microstrip line, the eleventh microstrip line, the twelfth microstrip line, the fourteenth microstrip line, the first open branch and the second open branch.

3. The topological structure according to claim 1, characterized in that: The first parallel lines include a first transmission line and a second transmission line arranged in parallel, the first transmission line is connected to the input end and one end of the first microstrip line, and the second transmission line is connected to one end of the third microstrip line, one end of the ninth microstrip line and one end of the second parallel line.

4. The topological structure according to claim 3, characterized in that: The second parallel lines include a third transmission line and a fourth transmission line arranged in parallel, the third transmission line is connected to the other end of the second transmission line, one end of the third microstrip line and one end of the ninth microstrip line, and the fourth transmission line is connected to one end of the third parallel line, one end of the eighth microstrip line and one end of the fourteenth microstrip line.

5. The topological structure according to claim 4, characterized in that: The third parallel lines include a fifth transmission line and a sixth transmission line arranged in parallel, the fifth transmission line is connected to the fourth transmission line, one end of the eighth microstrip line and one end of the fourteenth microstrip line, and the sixth transmission line is connected to the output end and one end of the second microstrip line.

6. The topological structure according to claim 1, characterized in that: The electrical length of the first parallel line, the electrical length of the second parallel line, and the electrical length of the third parallel line are equal, and are all equal to a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

7. The topological structure according to claim 1, characterized in that: The electrical length of the first microstrip line is equal to the electrical length of the second microstrip line, the electrical length of the first open branch is equal to the electrical length of the second open branch, and the sum of the electrical length of the first microstrip line and the electrical length of the first open branch is a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure, and is also a quarter wavelength corresponding to the notch center frequency of the bandpass filter designed based on the topological structure.

8. The topological structure according to claim 1, characterized in that: The sum of the electrical lengths of the third microstrip line, the fourth microstrip line, the fifth microstrip line and the first short-circuit branch is greater than a quarter wavelength corresponding to the center frequency of the bandpass filter designed based on the topological structure.

9. A filter, characterized in that: Comprising a topological structure as described in any one of claims 1-8.

10. A communication device, characterized in that: Comprising a filter designed based on the topology structure as claimed in claim 9.

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