Topological structure, filter and communication equipment

Abstract

The embodiment of the utility model relates to the technical field of communication, in particular to a topological structure, a filter and communication equipment. The topological structure comprises 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 and a thirteenth microstrip line. A fourteenth microstrip line, a fifteenth microstrip line, a sixteenth microstrip line, a seventeenth microstrip line, an eighteenth microstrip line, a nineteenth microstrip line, a twentieth microstrip line, a twenty-first microstrip line, a twenty-second microstrip line, a first open-circuit branch, a second open-circuit branch, a first short-circuit branch, a second short-circuit branch, a third short-circuit branch, a fourth short-circuit branch and a fifth short-circuit branch. And a sixth short-circuit branch, a seventh short-circuit branch and an eighth short-circuit branch. Therefore, the selectivity of the filter is improved.

Description

Technical Field

[0001] The embodiments of the utility model relate to the field of communication technology, and in particular to a topology structure, a filter and a communication device. Background Art

[0002] With the rapid development of modern 5G communication technology, broadband bandpass filters, as one of the key components of wireless communication systems, have attracted increasing attention from scholars and engineers. In this context, a large number of bandpass filters with notch characteristics that can suppress in-band interference and transmit signals at high speeds have been developed.

[0003] During the process of realizing the present invention, the inventors found that most of the broadband bandpass filters with notch characteristics currently have the defect of poor selectivity, which greatly limits their use in modern wireless communication systems. Utility Model Content

[0004] The main technical problem solved by the embodiments of the present utility model is to provide a topology structure, a filter and a communication device, which can improve selectivity.

[0005] To solve the above technical problems, the utility model adopts one technical scheme, which provides a topology structure, the topology structure includes input, output, first parallel line, second parallel line, third parallel line, first microstrip line, second microstrip line, third microstrip line, fourth microstrip line, fifth microstrip line, sixth microstrip line, seventh microstrip line, eighth microstrip line, ninth microstrip line, tenth microstrip line, eleventh microstrip line, twelfth microstrip line, thirteenth microstrip line, fourteenth microstrip line, fifteenth microstrip line, sixteenth microstrip line, seventeenth microstrip line, eighteenth microstrip line, nineteenth microstrip line, twentieth microstrip line, twenty -first microstrip line, twenty -second microstrip line, first open -circuit stub, Second open -circuit stub, first short -circuit stub, second short -circuit stub, third short -circuit stub, fourth short -circuit stub, fifth short -circuit stub, sixth short -circuit stub, seventh short -circuit stub and eighth short -circuit stub, one end of first microstrip line and one end of first parallel line are connected to input, the other end of first microstrip line is connected to first open -circuit stub, one end of second microstrip line, one end of seventh microstrip line and one end of second parallel line are connected to the other end of first parallel line, the other end of second microstrip line is connected to one end of third microstrip line and one end of fifth microstrip line, the other end of third microstrip line is connected to one end of fourth microstrip line, the other end of fourth microstrip line is connected to first short -circuit stub, the other end of fifth microstrip line is connected to one end of sixth microstrip line, the other end of sixth microstrip line is connected to second short -circuit stub, the other end of seventh microstrip line is connected to one end of eighth microstrip line and one end of tenth microstrip line, the other end of eighth microstrip line is connected to one end of ninth microstrip line, the other end of ninth microstrip line is connected to third short -circuit stub, the other end of tenth microstrip line is connected to one end of eleventh microstrip line, the other end of eleventh microstrip line is connected to fourth short -circuit stub, one end of twelfth microstrip line, one end of seventeenth microstrip line and one end of third parallel line are connected to the other end of second parallel line, the other end of twelfth microstrip line is connected to one end of thirteenth microstrip line and one end of fifteenth microstrip line, the other end of thirteenth microstrip line is connected to one end of fourteenth microstrip line, the other end of fourteenth microstrip line is connected to fifth short -circuit stub, the other end of fifteenth microstrip line is connected to one end of sixteenth microstrip line, the other end of sixteenth microstrip line is connected to sixth short -circuit stub, the other end of seventeenth microstrip line is connected to one end of eighteenth microstrip line and one end of twentieth microstrip line, the other end of eighteenth microstrip line is connected to one end of nineteenth microstrip line, the other end of nineteenth microstrip line is connected to seventh short -circuit stub, the other end of twentieth microstrip line is connected to one end of twenty -first microstrip line, the other end of twenty -first microstrip line is connected to eighth short -circuit stub, the other end of third parallel line is connected to one end of twenty -second microstrip line and output, the other end of twenty -second microstrip line is connected to second open -circuit stub.

[0006] Optionally, the first parallel line, the second parallel line, the third parallel line, the first microstrip line, the third microstrip line, the fifth microstrip line, the eighth microstrip line, the tenth microstrip line, the thirteenth microstrip line, the fifteenth microstrip line, the eighteenth microstrip line, the twentieth microstrip line, the twenty-second microstrip line, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch, the fourth short-circuit branch, the fifth short-circuit branch, the sixth short-circuit branch, the seventh short-circuit branch, and the eighth short-circuit branch are parallel to each other and are all perpendicular to the second microstrip line, the fourth microstrip line, the sixth microstrip line, the seventh microstrip line, the ninth microstrip line, the eleventh microstrip line, the twelfth microstrip line, the fourteenth microstrip line, the sixteenth microstrip line, the seventeenth microstrip line, the nineteenth microstrip line, the twenty-first microstrip line, the first open branch and the second open branch.

[0007] Optionally, the third microstrip line and the fifth microstrip line, the fourth microstrip line and the sixth microstrip line, the first short-circuit branch and the second short-circuit branch, the eighth microstrip line and the tenth microstrip line, the ninth microstrip line and the eleventh microstrip line, the third short-circuit branch and the fourth short-circuit branch are symmetrical about the perpendicular bisector of the seventh microstrip line or the perpendicular bisector of the second microstrip line; the thirteenth microstrip line and the fifteenth microstrip line, the fourteenth microstrip line and the sixteenth microstrip line, the fifth short-circuit branch and the sixth short-circuit branch, the eighteenth microstrip line and the twentieth microstrip line, the nineteenth microstrip line and the twenty-first microstrip line, the seventh short-circuit branch and the eighth short-circuit branch are symmetrical about the perpendicular bisector of the twelfth microstrip line or the perpendicular bisector of the seventeenth microstrip line.

[0008] Optionally, the second microstrip line and the seventh microstrip line, the third microstrip line and the eighth microstrip line, the fourth microstrip line and the ninth microstrip line, the fifth microstrip line and the tenth microstrip line, the sixth microstrip line and the eleventh microstrip line, the first short-circuit branch and the third short-circuit branch, the second short-circuit branch and the fourth short-circuit branch, the twelfth microstrip line and the seventeenth microstrip line, the thirteenth microstrip line and the eighteenth microstrip line, the fourteenth microstrip line and the nineteenth microstrip line, the fifteenth microstrip line and the twentieth microstrip line, the sixteenth microstrip line and the twenty-first microstrip line, the fifth short-circuit branch and the seventh short-circuit branch, the sixth short-circuit branch and the eighth short-circuit branch are all symmetrical about the perpendicular bisector of the first parallel line or the perpendicular bisector of the second parallel line or the perpendicular bisector of the third parallel 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 broadband bandpass filter.

[0010] Optionally, the electrical length of the first microstrip line is equal to the electrical length of the twenty-second microstrip line; the electrical length of the first open branch is equal to the electrical length of the second open branch; the sum of the electrical length of the first microstrip line and the electrical length of the first open branch is one-quarter wavelength corresponding to the notch center frequency.

[0011] Optionally, the electrical length of the second microstrip line, the electrical length of the seventh microstrip line, the electrical length of the twelfth microstrip line, and the electrical length of the seventeenth microstrip line are equal; the electrical length of the third microstrip line, the electrical length of the fifth microstrip line, the electrical length of the eighth microstrip line, the electrical length of the tenth microstrip line, the electrical length of the thirteenth microstrip line, the electrical length of the fifteenth microstrip line, the electrical length of the eighteenth microstrip line, and the electrical length of the twentieth microstrip line are equal; the electrical length of the fourth microstrip line, the electrical length of the sixth microstrip line, the electrical length of the ninth microstrip line, the electrical length of the eleventh microstrip line, the electrical length of the fourteenth microstrip line, the electrical length of the sixteenth microstrip line The electrical length of the microstrip line, the electrical length of the nineteenth microstrip line, and the electrical length of the twenty-first microstrip line are equal; the electrical length of the first short-circuit branch, the electrical length of the second short-circuit branch, the electrical length of the third short-circuit branch, the electrical length of the fourth short-circuit branch, the electrical length of the fifth short-circuit branch, the electrical length of the sixth short-circuit branch, the electrical length of the seventh short-circuit branch, and the electrical length of the eighth short-circuit branch are equal; the sum of the electrical length of the second microstrip line, the electrical length of the third microstrip line, the electrical length of the fourth microstrip line, and the electrical length of the first short-circuit branch is greater than one-quarter wavelength corresponding to the center frequency of the broadband bandpass filter.

[0012] Optionally, the odd-mode characteristic impedance of the first parallel line is equal to the odd-mode characteristic impedance of the third parallel line, the even-mode characteristic impedance of the first parallel line is equal to the even-mode characteristic impedance of the third parallel line; the characteristic impedance of the first microstrip line, the characteristic impedance of the twenty-second microstrip line, and the characteristic impedance of the first open branch are equal to the second open branch; the characteristic impedance of the second microstrip line, the characteristic impedance of the seventh microstrip line, the characteristic impedance of the twelfth microstrip line, and the characteristic impedance of the seventeenth microstrip line are equal; the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line, the characteristic impedance of the fifth microstrip line, the characteristic impedance of the sixth microstrip line, the characteristic impedance of the eighth microstrip line, the characteristic impedance of the ninth microstrip line, and the characteristic impedance of the tenth microstrip line are equal. The characteristic impedance of the first short-circuit branch, the characteristic impedance of the second short-circuit branch, the characteristic impedance of the third short-circuit branch, the characteristic impedance of the fourth short-circuit branch, the characteristic impedance of the fifth short-circuit branch, the characteristic impedance of the sixth short-circuit branch, the characteristic impedance of the seventh short-circuit branch, and the characteristic impedance of the eighth short-circuit branch are equal and are all twice the characteristic impedance of the second microstrip line.

[0013] In order to solve the above technical problems, another technical solution adopted by the present invention is: to provide a filter, including the topology structure as described in any one of the above embodiments.

[0014] In order to solve the above technical problem, another technical solution adopted by the present invention is: providing a communication device, including the filter described in the above embodiment.

[0015] The beneficial effects of the embodiment of the utility model are as follows: different from the prior art, the embodiment of the utility model provides 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 fifteenth microstrip line, a sixteenth microstrip line, a seventeenth microstrip line, an eighteenth microstrip line, a nineteenth microstrip line, a twentieth microstrip line, a twenty-first microstrip line, a twenty-second microstrip line, a first open branch, The second open-circuit branch, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch, the fourth short-circuit branch, the fifth short-circuit branch, the sixth short-circuit branch, the seventh short-circuit branch and the eighth short-circuit branch; one end of the first microstrip line and one end of the first parallel line are both connected to the input end, the other end of the first microstrip line is connected to the first open-circuit branch, one end of the second microstrip line, one end of the seventh microstrip line and one end of the second parallel line are all connected to the other end of the first parallel line, the other end of the second microstrip line is connected to one end of the third microstrip line and one end of the fifth microstrip line, the other end of the third microstrip line is connected to one end of the fourth microstrip line, the other end of the fourth microstrip line is connected to the first short-circuit branch, and the other end of the fifth microstrip line is connected to the first short-circuit branch. One end of the sixth microstrip line and the other end of the sixth microstrip line are connected to the second short-circuit branch, the other end of the seventh microstrip line is connected to one end of the eighth microstrip line and one end of the tenth microstrip line, the other end of the eighth microstrip line is connected to one end of the ninth microstrip line, the other end of the ninth microstrip line is connected to the third short-circuit branch, the other end of the tenth microstrip line is connected to one end of the eleventh microstrip line, the other end of the eleventh microstrip line is connected to the fourth short-circuit branch, one end of the twelfth microstrip line, one end of the seventeenth microstrip line and one end of the third parallel line are all connected to the other end of the second parallel line, the other end of the twelfth microstrip line is connected to one end of the thirteenth microstrip line and one end of the fifteenth microstrip line, the other end of the thirteenth microstrip line is connected to the fourteenth microstrip line The first microstrip line is connected to one end of the line, the other end of the fourteenth microstrip line is connected to the fifth short-circuit branch, the other end of the fifteenth microstrip line is connected to one end of the sixteenth microstrip line, the other end of the sixteenth microstrip line is connected to the sixth short-circuit branch, the other end of the seventeenth microstrip line is connected to one end of the eighteenth microstrip line and one end of the twentieth microstrip line, the other end of the eighteenth microstrip line is connected to one end of the nineteenth microstrip line, the other end of the nineteenth microstrip line is connected to the seventh short-circuit branch, the other end of the twentieth microstrip line is connected to one end of the twenty-first microstrip line, the other end of the twenty-first microstrip line is connected to the eighth short-circuit branch, the other end of the third parallel line is connected to one end of the twenty-second microstrip line and the output end, and the other end of the twenty-second microstrip line is connected to the second open-circuit branch. In the above manner, the selectivity of the filter based on this topology is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. 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 creative work.

[0017] Figure 1 It is a schematic diagram of the topological structure of an embodiment of the present utility model;

[0018] Figure 2 This is a schematic diagram of a simulation structure of the topological structure of an embodiment of the utility model;

[0019] Figure 3 This is a diagram of S-parameter simulation results of the topological structure of an embodiment of the present utility model;

[0020] Figure 4 This is an equivalent structural diagram of an odd-mode form of the topological structure of an embodiment of the present utility model;

[0021] Figure 5 It is an equivalent structural diagram of the even-mode form of the topological structure of the embodiment of the utility model.

[0022] Description of reference numerals:

[0023] 100, input terminal; 101, output terminal;

[0024] 200, first parallel line; 201, second parallel line; 202, third parallel line;

[0025] 300, first microstrip line; 301, second microstrip line; 302, third microstrip line; 303, fourth microstrip line; 304, fifth microstrip line; 305, sixth microstrip line; 306, seventh microstrip line; 307, eighth microstrip line; 308, ninth microstrip line; 309, tenth microstrip line; 310, eleventh microstrip line; 311, twelfth microstrip line; 312, thirteenth microstrip line; 313, fourteenth microstrip line; 314, fifteenth microstrip line; 315, sixteenth microstrip line; 316, seventeenth microstrip line; 317, eighteenth microstrip line; 318, nineteenth microstrip line; 319, twentieth microstrip line; 320, twenty-first microstrip line; 321, twenty-second microstrip line;

[0026] 400, first open branch; 401, second open branch;

[0027] 500, first short-circuit branch; 501, second short-circuit branch; 502, third short-circuit branch; 503, fourth short-circuit branch; 504, fifth short-circuit branch; 505, sixth short-circuit branch; 506, seventh short-circuit branch; 507, eighth short-circuit branch;

[0028] 600, odd-mode transmission line; 601, even-mode transmission line;

[0029] 1000. Topological structure. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention 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.

[0031] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this utility model belongs. The terms used in this specification and in the description of this utility model are only for the purpose of describing specific embodiments and are not intended to limit the utility model. The term "and / or" used in this specification includes any and all combinations of one or more of the relevant listed items.

[0032] See also Figure 1 and 2 The topology structure 1000 includes an input terminal 100, an output terminal 101, a first parallel line 200, a second parallel line 201, a third parallel line 202, a first microstrip line 300, a second microstrip line 301, a third microstrip line 302, a fourth microstrip line 303, a fifth microstrip line 304, a sixth microstrip line 305, a seventh microstrip line 306, an eighth microstrip line 307, a ninth microstrip line 308, a tenth microstrip line 309, an eleventh microstrip line 310, a twelfth microstrip line 311, a thirteenth microstrip line 312, a fourteenth microstrip line 313, The fifteenth microstrip line 314, the sixteenth microstrip line 315, the seventeenth microstrip line 316, the eighteenth microstrip line 317, the nineteenth microstrip line 318, the twentieth microstrip line 319, the twenty-first microstrip line 320, the twenty-second microstrip line 321, the first open-circuit branch 400, the second open-circuit branch 401, the first short-circuit branch 500, the second short-circuit branch 501, the third short-circuit branch 502, the fourth short-circuit branch 503, the fifth short-circuit branch 504, the sixth short-circuit branch 505, the seventh short-circuit branch 506 and the eighth short-circuit branch 507.

[0033] Specifically, one end of the first microstrip line 300 and one end of the first parallel line 200 are both connected to the input terminal 100, the other end of the first microstrip line 300 is connected to the first open-circuit branch 400, one end of the second microstrip line 301, one end of the seventh microstrip line 306, and one end of the second parallel line 201 are all connected to the other end of the first parallel line 200, the other end of the second microstrip line 301 is connected to one end of the third microstrip line 302 and one end of the fifth microstrip line 304, the other end of the third microstrip line 302 is connected to one end of the fourth microstrip line 303, and the other end of the fourth microstrip line 303 is connected to the first short-circuit branch 500. The other end of the fifth microstrip line 304 is connected to one end of the sixth microstrip line 305, the other end of the sixth microstrip line 305 is connected to the second short-circuit branch 501, the other end of the seventh microstrip line 306 is connected to one end of the eighth microstrip line 307 and one end of the tenth microstrip line 309, the other end of the eighth microstrip line 307 is connected to one end of the ninth microstrip line 308, the other end of the ninth microstrip line 308 is connected to the third short-circuit branch 502, the other end of the tenth microstrip line 309 is connected to one end of the eleventh microstrip line 310, the other end of the eleventh microstrip line 310 is connected to the fourth short-circuit branch 503, and the twelfth microstrip line 311 is connected to the fourth short-circuit branch 503. One end of the 17th microstrip line 316 and one end of the third parallel line 202 are all connected to the other end of the second parallel line 201, the other end of the 12th microstrip line 311 is connected to one end of the 13th microstrip line 312 and one end of the 15th microstrip line 314, the other end of the 13th microstrip line 312 is connected to one end of the 14th microstrip line 313, the other end of the 14th microstrip line 313 is connected to the fifth short-circuit branch 504, the other end of the 15th microstrip line 314 is connected to one end of the 16th microstrip line 315, the other end of the 16th microstrip line 315 is connected to the sixth short-circuit branch 505, and the 17th microstrip line 316 is connected to one end of the 16th microstrip line 315. The other end of the third parallel line 202 is connected to one end of the eighteenth microstrip line 317 and one end of the twentieth microstrip line 319, the other end of the eighteenth microstrip line 317 is connected to one end of the nineteenth microstrip line 318, the other end of the nineteenth microstrip line 318 is connected to the seventh short-circuit branch 506, the other end of the twentieth microstrip line 319 is connected to one end of the twenty-first microstrip line 320, the other end of the twenty-first microstrip line 320 is connected to the eighth short-circuit branch 507, the other end of the third parallel line 202 is connected to one end of the twenty-second microstrip line 321 and the output end 101, and the other end of the twenty-second microstrip line 321 is connected to the second open-circuit branch 401.

[0034] In some embodiments, the first parallel line 200, the second parallel line 201, the third parallel line 202, the first microstrip line 300, the third microstrip line 302, the fifth microstrip line 304, the eighth microstrip line 307, the tenth microstrip line 309, the thirteenth microstrip line 312, the fifteenth microstrip line 314, the eighteenth microstrip line 317, the twentieth microstrip line 319, the twenty-second microstrip line 321, the first short-circuit branch 500, the second short-circuit branch 501, the third short-circuit branch 502, the fourth short-circuit branch 503, the fifth short-circuit branch 504, the fifth short-circuit branch 505, the fifth short-circuit branch 506, the fifth short-circuit branch 507, the fifth short-circuit branch 508, the fifth short-circuit branch 509, the fifth short-circuit branch 510, the fifth short-circuit branch 511, the fifth short-circuit branch 512, the fifth short-circuit branch 513, the fifth short-circuit branch 514, the fifth short-circuit branch 517, the fifth short-circuit branch 519, the fifth short-circuit branch 511, the fifth short-circuit branch 513, the fifth short-circuit branch 514 04. The sixth short-circuit branch 505, the seventh short-circuit branch 506, and the eighth short-circuit branch 507 are parallel to each other and are perpendicular to the second microstrip line 301, the fourth microstrip line 303, the sixth microstrip line 305, the seventh microstrip line 306, the ninth microstrip line 308, the eleventh microstrip line 310, the twelfth microstrip line 311, the fourteenth microstrip line 313, the sixteenth microstrip line 315, the seventeenth microstrip line 316, the nineteenth microstrip line 318, the twenty-first microstrip line 320, the first open-circuit branch 400, and the second open-circuit branch 401.

[0035] In some embodiments, the third microstrip line 302 and the fifth microstrip line 304, the fourth microstrip line 303 and the sixth microstrip line 305, the first short-circuit stub 500 and the second short-circuit stub 501, the eighth microstrip line 307 and the tenth microstrip line 309, the ninth microstrip line 308 and the eleventh microstrip line 310, the third short-circuit stub 502 and the fourth short-circuit stub 503 are symmetrical about the perpendicular midline of the seventh microstrip line 306 or the perpendicular midline of the second microstrip line 301; The thirteenth microstrip line 312 and the fifteenth microstrip line 314, the fourteenth microstrip line 313 and the sixteenth microstrip line 315, the fifth short-circuit branch 504 and the sixth short-circuit branch 505, the eighteenth microstrip line 317 and the twentieth microstrip line 319, the nineteenth microstrip line 318 and the twenty-first microstrip line 320, the seventh short-circuit branch 506 and the eighth short-circuit branch 507 are symmetrical about the perpendicular bisector of the twelfth microstrip line 311 or the perpendicular bisector of the seventeenth microstrip line 316.

[0036] In some embodiments, the second microstrip line 301 and the seventh microstrip line 306, the third microstrip line 302 and the eighth microstrip line 307, the fourth microstrip line 303 and the ninth microstrip line 308, the fifth microstrip line 304 and the tenth microstrip line 309, the sixth microstrip line 305 and the eleventh microstrip line 310, the first short-circuit stub 500 and the third short-circuit stub 502, the second short-circuit stub 501 and the fourth short-circuit stub 503, the twelfth microstrip line 311 and the seventeenth microstrip line 316, the tenth The third microstrip line 312 and the eighteenth microstrip line 317, the fourteenth microstrip line 313 and the nineteenth microstrip line 318, the fifteenth microstrip line 314 and the twentieth microstrip line 319, the sixteenth microstrip line 315 and the twenty-first microstrip line 320, the fifth short-circuit branch 504 and the seventh short-circuit branch 506, the sixth short-circuit branch 505 and the eighth short-circuit branch 507 are all symmetrical about the perpendicular bisector of the first parallel line 200 or the perpendicular bisector of the second parallel line 201 or the perpendicular bisector of the third parallel line 202.

[0037] In some embodiments, the electrical lengths of the first parallel line 200 , the second parallel line 201 , and the third parallel line 202 are equal and are all equal to a quarter wavelength corresponding to the center frequency of the broadband bandpass filter.

[0038] In some embodiments, the electrical length of the first microstrip line 300 is equal to the electrical length of the twenty-second microstrip line 321; the electrical length of the first open branch 400 is equal to the electrical length of the second open branch 401; the sum of the electrical length of the first microstrip line 300 and the electrical length of the first open branch 400 is one-quarter wavelength corresponding to the notch center frequency.

[0039] In some embodiments, the electrical length of the second microstrip line 301, the electrical length of the seventh microstrip line 306, the electrical length of the twelfth microstrip line 311, and the electrical length of the seventeenth microstrip line 316 are equal; the electrical length of the third microstrip line 302, the electrical length of the fifth microstrip line 304, the electrical length of the eighth microstrip line 307, the electrical length of the tenth microstrip line 309, the electrical length of the thirteenth microstrip line 312, the electrical length of the fifteenth microstrip line 314, the electrical length of the eighteenth microstrip line 317, and the electrical length of the twentieth microstrip line 319 are equal; the electrical length of the fourth microstrip line 303, the electrical length of the sixth microstrip line 305, the electrical length of the ninth microstrip line 308, the electrical length of the eleventh microstrip line 310, and the electrical length of the fourteenth microstrip line 313 are equal. The electrical length of the sixteenth microstrip line 315, the electrical length of the nineteenth microstrip line 318, and the electrical length of the twenty-first microstrip line 320 are equal; the electrical length of the first short-circuit branch 500, the electrical length of the second short-circuit branch 501, the electrical length of the third short-circuit branch 502, the electrical length of the fourth short-circuit branch 503, the electrical length of the fifth short-circuit branch 504, the electrical length of the sixth short-circuit branch 505, the electrical length of the seventh short-circuit branch 506, and the electrical length of the eighth short-circuit branch 507 are equal; the sum of the electrical length of the second microstrip line 301, the electrical length of the third microstrip line 302, the electrical length of the fourth microstrip line 303 and the electrical length of the first short-circuit branch 500 is greater than one-quarter wavelength corresponding to the center frequency of the broadband bandpass filter.

[0040] In some embodiments, the odd-mode characteristic impedance of the first parallel line 200 and the odd-mode characteristic impedance of the third parallel line 202 are equal and are both Zo1, the even-mode characteristic impedance of the first parallel line 200 and the even-mode characteristic impedance of the third parallel line 202 are equal and are both Ze1; the odd-mode characteristic impedance of the second parallel line 201 is Zo2; the even-mode characteristic impedance of the second parallel line 201 is Ze2; the characteristic impedance of the first microstrip line 300, the characteristic impedance of the twenty-second microstrip line 321, the characteristic impedance of the first open-circuit branch 400, and the second open-circuit branch 401 are equal; the characteristic impedance of the second microstrip line 301, the characteristic impedance of the seventh microstrip line 306, the characteristic impedance of the twelfth microstrip line 311, and the characteristic impedance of the seventeenth microstrip line 316 are equal and are all Z2; the characteristic impedance of the third microstrip line 302, the characteristic impedance of the fourth microstrip line 303, the characteristic impedance of the fifth microstrip line 304, and the characteristic impedance of the sixth microstrip line 305 , the characteristic impedance of the eighth microstrip line 307, the characteristic impedance of the ninth microstrip line 308, the characteristic impedance of the tenth microstrip line 309, the characteristic impedance of the eleventh microstrip line 310, the characteristic impedance of the thirteenth microstrip line 312, the characteristic impedance of the fourteenth microstrip line 313, the characteristic impedance of the fifteenth microstrip line 314, the characteristic impedance of the sixteenth microstrip line 315, the characteristic impedance of the eighteenth microstrip line 317, the characteristic impedance of the nineteenth microstrip line 318, the characteristic impedance of the twentieth microstrip line 319, the characteristic impedance of the twenty-first microstrip line 320, the characteristic impedance of the first short-circuit branch 500, the characteristic impedance of the second short-circuit branch 501, the characteristic impedance of the third short-circuit branch 502, the characteristic impedance of the fourth short-circuit branch 503, the characteristic impedance of the fifth short-circuit branch 504, the characteristic impedance of the sixth short-circuit branch 505, the characteristic impedance of the seventh short-circuit branch 506, and the characteristic impedance of the eighth short-circuit branch 507 are equal and are all 2Z2.

[0041] To facilitate readers' understanding, a simulation example of topology 1000 is provided below:

[0042] See also Figure 2 The topological structure 1000 is mounted on a circuit board (not shown). The circuit board has dimensions of 34.4 mm by 11.1 mm, a dielectric constant of 3.38, a dielectric loss of 0.0022, and a thickness of 0.813 mm. The specific dimensions of the topological structure 1000 are: l P1 = 9.6 mm, s P1 = 0.1 mm, w P1 = 0.3 mm, l P2 = 9.6 mm, s P2 = 0.15 mm, w P2 = 0.2 mm, l 1 = 8.6 mm, l 2 = 2.0 mm, l 3 = 4.3 mm, l 4 = 3.8 mm, l 5 = 2.4 mm, l 6 = 1.8 mm, w 1 = 0.3 mm, w 1 = 1.0 mm, w 2 = 0.5 mm, and s 1 = 0.15 mm.

[0043] l P1 represents a physical length of the first parallel line 200 or a physical length of the third parallel line 202;

[0044] sP1 represents a pitch of the first transmission line and the second transmission line constituting the first parallel line 200, or a pitch of the fifth transmission line and the sixth transmission line constituting the third parallel line 202;

[0045] wP1 represents a physical width of the first transmission line or a physical width of the second transmission line or a physical width of the fifth transmission line or a physical width of the sixth transmission line;

[0046] l P2 represents a physical length of the second parallel line 201;

[0047] sP2 represents a pitch of the third transmission line and the fourth transmission line constituting the second parallel line 201;

[0048] wP2 represents a physical width of the third transmission line or a physical width of the fourth transmission line;

[0049] l 1 represents a physical length of the first microstrip line 300 or a physical length of the twenty-second microstrip line 321;

[0050] l 2 represents a physical length of the first open stub 400 or a physical length of the second open stub 401;

[0051] l 3 represents a physical length of the second microstrip line 301 or a physical length of the seventh microstrip line 306 or a physical length of the twelfth microstrip line 311 or a physical length of the seventeenth microstrip line 316;

[0052] l4 represents a physical length of the third microstrip line 302 or a physical length of the fifth microstrip line 304 or a physical length of the eighth microstrip line 307 or a physical length of the tenth microstrip line 309 or a physical length of the thirteenth microstrip line 312 or a physical length of the fifteenth microstrip line 314 or a physical length of the eighteenth microstrip line 317 or a physical length of the twentieth microstrip line 319;

[0053] l5 represents a physical length of the fourth microstrip line 303 or a physical length of the sixth microstrip line 305 or a physical length of the ninth microstrip line 308 or a physical length of the eleventh microstrip line 310 or a physical length of the fourteenth microstrip line 313 or a physical length of the sixteenth microstrip line 315 or a physical length of the nineteenth microstrip line 318 or a physical length of the twenty-first microstrip line 320;

[0054] l 6 represents a physical length of the first short stub 500 or a physical length of the second short stub 501 or a physical length of the third short stub 502 or a physical length of the fourth microstrip line 303 or a physical length of the fifth short stub 504 or a physical length of the sixth short stub 505 or a physical length of the seventh short stub 506 or a physical length of the eighth microstrip line 307;

[0055] w1 represents the physical width of the first microstrip line 300 or the physical width of the twenty-second microstrip line 321 or the physical width of the first open stub 400 or the width of the second open stub 401;

[0056] w2 represents the physical width of the second microstrip line 301 or the physical width of the seventh microstrip line 306 or the physical width of the twelfth microstrip line 311 or the physical width of the seventeenth microstrip line 316;

[0057] w2 represents the physical width of the third microstrip line 302 or the physical width of the fourth microstrip line 303 or the physical width of the fifth microstrip line 304 or the physical width of the sixth microstrip line 305 or the physical width of the eighth microstrip line 307 or the physical width of the ninth microstrip line 308 or the physical width of the tenth microstrip line 309 or the physical width of the eleventh microstrip line 310 or the physical width of the thirteenth microstrip line 312 or the physical width of the fourteenth microstrip line 313 or the physical width of the fifteenth microstrip line 314 or the physical width of the sixteenth microstrip line 315 or the physical width of the tenth microstrip line 316 the physical width of the eighth microstrip line 317, or the physical width of the nineteenth microstrip line 318, or the physical width of the twentieth microstrip line 319, or the physical width of the twenty-first microstrip line 320, or the physical width of the first short-circuit stub 500, or the physical width of the second short-circuit stub 501, or the physical width of the third short-circuit stub 502, or the physical width of the fourth short-circuit stub 503, or the physical width of the fifth short-circuit stub 504, or the physical width of the sixth short-circuit stub 505, or the physical width of the seventh short-circuit stub 506, or the physical width of the eighth short-circuit stub 507;

[0058] s1 represents the distance between the first microstrip line 300 and the first parallel line 200 , or the distance between the twenty-second microstrip line 321 and the third parallel line 202 .

[0059] See also Figure 3 The figure shows the simulation results based on the above dimensions and parameters. The figure also shows the S-parameter simulation results. Specifically, the passband with a reflection coefficient better than -10dB ranges from 2.62GHz to 7.16GHz, with a center frequency of 4.89GHz, an absolute bandwidth of 4.54GHz, and a relative bandwidth of 92.8%. Furthermore, seven transmission poles within the passband—located at 2.71, 3.39, 4.35, 5.26, 5.84, 6.82, and 7.09GHz—ensure passband flatness. A transmission zero within the passband, located at 4.88GHz, creates the required notch. The isolation at the notch's center frequency is 29.4dB, demonstrating excellent isolation. Five transmission zeros within the stopband—located at 0, 0.18, 7.68, 8.5, 9.16, and 10.76GHz—ensure the filter's high selectivity and high isolation in the stopband.

[0060] Through the simulation example of the above topology structure 1000 , it can be proved that the filter designed based on the above topology structure 1000 has a compact structure and high selectivity.

[0061] In the embodiment of the present utility model, the topological structure 1000 includes an input terminal 100, an output terminal 101, a first parallel line 200, a second parallel line 201, a third parallel line 202, a first microstrip line 300, a second microstrip line 301, a third microstrip line 302, a fourth microstrip line 303, a fifth microstrip line 304, a sixth microstrip line 305, a seventh microstrip line 306, an eighth microstrip line 307, a ninth microstrip line 308, a tenth microstrip line 309, an eleventh microstrip line 310, a twelfth microstrip line 311, a thirteenth microstrip line 312, a fourteenth microstrip line line 313, a fifteenth microstrip line 314, a sixteenth microstrip line 315, a seventeenth microstrip line 316, an eighteenth microstrip line 317, a nineteenth microstrip line 318, a twentieth microstrip line 319, a twenty-first microstrip line 320, a twenty-second microstrip line 321, a first open-circuit branch 400, a second open-circuit branch 401, a first short-circuit branch 500, a second short-circuit branch 501, a third short-circuit branch 502, a fourth short-circuit branch 503, a fifth short-circuit branch 504, a sixth short-circuit branch 505, a seventh short-circuit branch 506, and an eighth short-circuit branch 507;One end of the first microstrip line 300 and one end of the first parallel line 200 are both connected to the input terminal 100, the other end of the first microstrip line 300 is connected to the first open-circuit branch 400, one end of the second microstrip line 301, one end of the seventh microstrip line 306, and one end of the second parallel line 201 are all connected to the other end of the first parallel line 200, the other end of the second microstrip line 301 is connected to one end of the third microstrip line 302 and one end of the fifth microstrip line 304, the other end of the third microstrip line 302 is connected to one end of the fourth microstrip line 303, the other end of the fourth microstrip line 303 is connected to the first short-circuit branch 500, and the The other end of the fifth microstrip line 304 is connected to one end of the sixth microstrip line 305, the other end of the sixth microstrip line 305 is connected to the second short-circuit branch 501, the other end of the seventh microstrip line 306 is connected to one end of the eighth microstrip line 307 and one end of the tenth microstrip line 309, the other end of the eighth microstrip line 307 is connected to one end of the ninth microstrip line 308, the other end of the ninth microstrip line 308 is connected to the third short-circuit branch 502, the other end of the tenth microstrip line 309 is connected to one end of the eleventh microstrip line 310, the other end of the eleventh microstrip line 310 is connected to the fourth short-circuit branch 503, and the twelfth microstrip line 311 is connected to the fourth short-circuit branch 503. One end of the 17th microstrip line 316 and one end of the third parallel line 202 are all connected to the other end of the second parallel line 201, the other end of the 12th microstrip line 311 is connected to one end of the 13th microstrip line 312 and one end of the 15th microstrip line 314, the other end of the 13th microstrip line 312 is connected to one end of the 14th microstrip line 313, the other end of the 14th microstrip line 313 is connected to the fifth short-circuit branch 504, the other end of the 15th microstrip line 314 is connected to one end of the 16th microstrip line 315, the other end of the 16th microstrip line 315 is connected to the sixth short-circuit branch 505, and the 17th microstrip line 316 is connected to the sixth short-circuit branch 505. The other end of 316 is connected to one end of the eighteenth microstrip line 317 and one end of the twentieth microstrip line 319. The other end of the eighteenth microstrip line 317 is connected to one end of the nineteenth microstrip line 318. The other end of the nineteenth microstrip line 318 is connected to the seventh short-circuit stub 506. The other end of the twentieth microstrip line 319 is connected to one end of the twenty-first microstrip line 320. The other end of the twenty-first microstrip line 320 is connected to the eighth short-circuit stub 507. The other end of the third parallel line 202 is connected to one end of the twenty-second microstrip line 321 and the output terminal 101. The other end of the twenty-second microstrip line 321 is connected to the second open-circuit stub 401. Through the above-described method, the selectivity of the filter based on this topology 1000 is improved.

[0062] The present invention provides a filter embodiment, which includes the above-mentioned topological structure 1000. The structure and function of the topological structure 1000 can be found in the above-mentioned embodiment, and will not be described in detail here.

[0063] To facilitate the reader's understanding, the following provides ideas for designing a filter with high selectivity based on the above topology 1000, as follows:

[0064] Assume that the sum of the electrical length of the first microstrip line 300 and the electrical length of the first open stub 400 is a quarter of the wavelength corresponding to the center frequency of the wideband bandpass filter, and the sum of the electrical length of the second microstrip line 301, the electrical length of the third microstrip line 302, the electrical length of the fourth microstrip line 303, and the electrical length of the first short stub 500 is also a quarter of the wavelength corresponding to the center frequency of the wideband bandpass filter. Since the topology 1000 can be equivalent to a symmetrical structure, its transmission poles can be calculated in the odd-even mode, and the calculation process is as follows:

[0065] First, get the odd mode form of the topology 1000, please refer to Figure 4 The electrical length of the odd mode transmission line 600 is the electrical length of the second parallel line 201; the characteristic impedance of the odd mode transmission line 600 is the odd mode characteristic impedance of the second parallel line 201.

[0066]

[0067] When the input admittance Yino = 0, it can be obtained that the topology 1000 has four odd mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the four odd mode transmission poles are respectively:

[0068]

[0069] Here,

[0070] Δ1 = 2Z2(Z e1 -Z o1 ) 2

[0071] Δ2 = 4Z2Z o2 (Z e1 +Z o1 +2) + 8Z2Z o1 Z e1 +Z o2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )

[0072] Δ3 = 4Z o1 Z e1 Z o2 +Z1Z o2

[0073] Then get the even mode form of the topology 1000, please refer to Figure 5, wherein the electrical length of the even-mode transmission line 601 is the electrical length of the second parallel line 201 ; the characteristic impedance of the even-mode transmission line 601 is the even-mode characteristic impedance of the second parallel line 201 .

[0074]

[0075] When the input admittance Yine = 0, it can be concluded that the topology 1000 has four even-mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the four even-mode transmission poles are:

[0076]

[0077] Here,

[0078] Δ1=2Z2(Z e1 -Z o1 ) 2

[0079] Δ2=4Z2Z e2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +Z e2 (Z e1 -Z e1 ) 2 +4Z1Z2(Z e1 +Z o1 )

[0080] Δ3=4Z o1 Z e1 Z e2 +Z1Z e2

[0081] For this topology 1000, its transmission zeros can be calculated by the following method: multiplying the ABCD matrices of the cascaded resonators that make up topology 1000 in sequence to obtain the ABCD matrix corresponding to topology 1000; and converting the ABCD matrix of topology 1000 into the corresponding S matrix. When |S21| = 0, it can be concluded that this topology 1000 has three transmission zeros, and the frequencies corresponding to the three transmission zeros are:

[0082] f z1 =0

[0083] f z2 =f0

[0084] f z3 =2f0

[0085] From the above analysis, it can be seen that when the sum of the electrical lengths of the first microstrip line 300 and the first open-circuit stub 400 is a quarter wavelength corresponding to the center frequency of the broadband bandpass filter, and the sum of the electrical lengths of the second microstrip line 301, the third microstrip line 302, the fourth microstrip line 303, and the first short-circuit stub 500 is also a quarter wavelength corresponding to the center frequency of the broadband bandpass filter, this topology 1000 has four odd-mode transmission poles, three even-mode transmission poles, and three transmission zeros. Returning to this topology 1000, adjusting the sum of the electrical lengths of the second microstrip line 301, the third microstrip line 302, the fourth microstrip line 303, and the first short-circuit stub 500 will result in three additional transmission zeros (fz4, fz5, fz6, fz6), but the number of existing poles and zeros remains unchanged. And no matter how the values ​​of parameters Zo1, Ze1, Zo2, Ze2, Z1 and Z2 are changed, the relative positions of the transmission zeros and poles, i.e. fz1 <fz4<fep1<fop1<fop2<fep2<fz2<fep3<fop3<fop4<fep4<fz5<fz3<fz6<fz7,都不会改变。此外,适当改变第一微带线300的电长度和第一开路枝节400的电长度之和的值,只会单独改变传输零点fz2的位置,而不会改变滤波器的其他性能。因此,基于此拓扑结构1000可以设计具有陷波特性的宽带带通滤波器,且在通带有多个传输极点以确保其带内的平坦度,在阻带内有六个传输零点以确保高选择性和

[0086] High isolation, with a transmission zero in the passband to form the required notch.

[0087] The present invention provides an embodiment of a communication device, which includes the above-mentioned filter. The structure and function of the filter can be found in the above-mentioned embodiment, and will not be described in detail here.

[0088] It should be noted that the preferred embodiments of the present invention are given in the specification and drawings of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments do not serve as additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention 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 considered to be within the scope of the description of the present invention; further, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A topological structure, characterized in that: 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 fifteenth microstrip line, a sixteenth microstrip line, a seventeenth microstrip line, an eighteenth microstrip line, a nineteenth microstrip line, a twentieth microstrip line, a twenty-first microstrip line, a twenty-second microstrip line, a first open-circuit branch, a second open-circuit branch, a first short-circuit branch, a second short-circuit branch, a third short-circuit branch, a fourth short-circuit branch, a fifth short-circuit branch, a sixth short-circuit branch, a seventh short-circuit branch, and an eighth short-circuit branch; One end of the first microstrip line and one end of the first parallel line are both connected to the input end, the other end of the first microstrip line is connected to the first open-circuit stub, one end of the second microstrip line, one end of the seventh microstrip line, and one end of the second parallel line are all connected to the other end of the first parallel line, the other end of the second microstrip line is connected to one end of the third microstrip line and one end of the fifth microstrip line, the other end of the third microstrip line is connected to one end of the fourth microstrip line, the other end of the fourth microstrip line is connected to the first short-circuit stub, the other end of the fifth microstrip line is connected to one end of the sixth microstrip line, the other end of the sixth microstrip line is connected to the second short-circuit stub, the other end of the seventh microstrip line is connected to one end of the eighth microstrip line and one end of the tenth microstrip line, the other end of the eighth microstrip line is connected to one end of the ninth microstrip line, the other end of the ninth microstrip line is connected to the third short-circuit stub, the other end of the tenth microstrip line is connected to one end of the eleventh microstrip line, the other end of the eleventh microstrip line is connected to the fourth short-circuit stub, one end of the twelfth microstrip line, One end of the seventeenth microstrip line and one end of the third parallel line are both connected to the other end of the second parallel line, the other end of the twelfth microstrip line is connected to one end of the thirteenth microstrip line and one end of the fifteenth microstrip line, the other end of the thirteenth microstrip line is connected to one end of the fourteenth microstrip line, the other end of the fourteenth microstrip line is connected to the fifth short-circuit stub, the other end of the fifteenth microstrip line is connected to one end of the sixteenth microstrip line, the other end of the sixteenth microstrip line is connected to the sixth short-circuit stub, the other end of the seventeenth microstrip line is connected to one end of the eighteenth microstrip line and one end of the twentieth microstrip line, the other end of the eighteenth microstrip line is connected to one end of the nineteenth microstrip line, the other end of the nineteenth microstrip line is connected to the seventh short-circuit stub, the other end of the twentieth microstrip line is connected to one end of the twenty-first microstrip line, the other end of the twenty-first microstrip line is connected to the eighth short-circuit stub, the other end of the third parallel line is connected to one end of the twenty-second microstrip line and the output end, and the other end of the twenty-second microstrip line is connected to the second open-circuit stub.

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 third microstrip line, the fifth microstrip line, the eighth microstrip line, the tenth microstrip line, the thirteenth microstrip line, the fifteenth microstrip line, the eighteenth microstrip line, the twentieth microstrip line, the twenty-second microstrip line, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch, the fourth short-circuit branch, the fifth short-circuit branch, the sixth short-circuit branch, the seventh short-circuit branch, and the eighth short-circuit branch are parallel to each other and are perpendicular to the second microstrip line, the fourth microstrip line, the sixth microstrip line, the seventh microstrip line, the ninth microstrip line, the eleventh microstrip line, the twelfth microstrip line, the fourteenth microstrip line, the sixteenth microstrip line, the seventeenth microstrip line, the nineteenth microstrip line, the twenty-first microstrip line, the first open branch, and the second open branch.

3. The topological structure according to claim 1, characterized in that: The third microstrip line and the fifth microstrip line, the fourth microstrip line and the sixth microstrip line, the first short-circuit stub and the second short-circuit stub, the eighth microstrip line and the tenth microstrip line, the ninth microstrip line and the eleventh microstrip line, the third short-circuit stub and the fourth short-circuit stub are symmetrical about the perpendicular bisector of the seventh microstrip line or the perpendicular bisector of the second microstrip line; The thirteenth microstrip line and the fifteenth microstrip line, the fourteenth microstrip line and the sixteenth microstrip line, the fifth short-circuit branch and the sixth short-circuit branch, the eighteenth microstrip line and the twentieth microstrip line, the nineteenth microstrip line and the twenty-first microstrip line, the seventh short-circuit branch and the eighth short-circuit branch are symmetrical about the perpendicular bisector of the twelfth microstrip line or the perpendicular bisector of the seventeenth microstrip line.

4. The topological structure according to claim 1, characterized in that: The second microstrip line and the seventh microstrip line, the third microstrip line and the eighth microstrip line, the fourth microstrip line and the ninth microstrip line, the fifth microstrip line and the tenth microstrip line, the sixth microstrip line and the eleventh microstrip line, the first short-circuit branch and the third short-circuit branch, the second short-circuit branch and the fourth short-circuit branch, the twelfth microstrip line and the seventeenth microstrip line, the thirteenth microstrip line and the eighteenth microstrip line, the fourteenth microstrip line and the nineteenth microstrip line, the fifteenth microstrip line and the twentieth microstrip line, the sixteenth microstrip line and the twenty-first microstrip line, the fifth short-circuit branch and the seventh short-circuit branch, the sixth short-circuit branch and the eighth short-circuit branch are all symmetrical about the perpendicular bisector of the first parallel line, the perpendicular bisector of the second parallel line, or the perpendicular bisector of the third parallel line.

5. 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 broadband bandpass filter.

6. 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 twenty-second microstrip line; the electrical length of the first open branch is equal to the electrical length of the second open branch; the sum of the electrical length of the first microstrip line and the electrical length of the first open branch is one-quarter wavelength corresponding to the notch center frequency.

7. The topological structure according to claim 1, characterized in that: The electrical length of the second microstrip line, the electrical length of the seventh microstrip line, the electrical length of the twelfth microstrip line, and the electrical length of the seventeenth microstrip line are equal; The electrical length of the third microstrip line, the electrical length of the fifth microstrip line, the electrical length of the eighth microstrip line, the electrical length of the tenth microstrip line, the electrical length of the thirteenth microstrip line, the electrical length of the fifteenth microstrip line, the electrical length of the eighteenth microstrip line, and the electrical length of the twentieth microstrip line are equal; the electrical length of the fourth microstrip line, the electrical length of the sixth microstrip line, the electrical length of the ninth microstrip line, the electrical length of the eleventh microstrip line, the electrical length of the fourteenth microstrip line, the electrical length of the sixteenth microstrip line, the electrical length of the nineteenth microstrip line, and the electrical length of the twenty-first microstrip line are equal; The electrical length of the first short-circuit branch, the electrical length of the second short-circuit branch, the electrical length of the third short-circuit branch, the electrical length of the fourth short-circuit branch, the electrical length of the fifth short-circuit branch, the electrical length of the sixth short-circuit branch, the electrical length of the seventh short-circuit branch, and the electrical length of the eighth short-circuit branch are equal; The sum of the electrical lengths of the second microstrip line, the third microstrip line, the fourth microstrip line, and the first short-circuit stub is greater than a quarter wavelength corresponding to the center frequency of the broadband bandpass filter.

8. The topological structure according to claim 1, characterized in that: The odd-mode characteristic impedance of the first parallel line is equal to the odd-mode characteristic impedance of the third parallel line, and the even-mode characteristic impedance of the first parallel line is equal to the even-mode characteristic impedance of the third parallel line; The characteristic impedance of the first microstrip line, the characteristic impedance of the twenty-second microstrip line, the characteristic impedance of the first open-circuit branch, and the characteristic impedance of the second open-circuit branch are equal; The characteristic impedance of the second microstrip line, the characteristic impedance of the seventh microstrip line, the characteristic impedance of the twelfth microstrip line, and the characteristic impedance of the seventeenth microstrip line are equal; The characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line, the characteristic impedance of the fifth microstrip line, the characteristic impedance of the sixth microstrip line, the characteristic impedance of the eighth microstrip line, the characteristic impedance of the ninth microstrip line, the characteristic impedance of the tenth microstrip line, the characteristic impedance of the eleventh microstrip line, the characteristic impedance of the thirteenth microstrip line, the characteristic impedance of the fourteenth microstrip line, the characteristic impedance of the fifteenth microstrip line, the characteristic impedance of the sixteenth microstrip line, the characteristic impedance of the eighteenth microstrip line, the characteristic impedance of the nineteenth microstrip line, the characteristic impedance of the twentieth microstrip line, the characteristic impedance of the twenty-first microstrip line, the characteristic impedance of the first short-circuit stub, the characteristic impedance of the second short-circuit stub, the characteristic impedance of the third short-circuit stub, the characteristic impedance of the fourth short-circuit stub, the characteristic impedance of the fifth short-circuit stub, the characteristic impedance of the sixth short-circuit stub, the characteristic impedance of the seventh short-circuit stub, and the characteristic impedance of the eighth short-circuit stub are equal and are all twice the characteristic impedance of the second microstrip line.

9. A filter, characterized in that: The method comprises the topological structure as claimed in any one of claims 1 to 8.

10. A communication device, characterized in that: Comprising the filter as claimed in claim 9.

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