Four-passband power dividing filter based on microstrip line multimode resonator

Abstract

The invention relates to a four-passband power dividing filter based on microstrip line four-mode resonators. The four-passband power dividing filter comprises a dielectric substrate, a metal grounding plate, a central input port feeder line, two output port feeder lines, four microstrip four-mode resonators and two isolation resistors. A first micro-strip four-mode resonator and a second micro-strip four-mode resonator are arranged between the central input port feeder line and the first output feeder line. A third micro-strip four-mode resonator and a fourth micro-strip four-mode resonator are arranged between the input port feeder line and the second output feeder line. The first isolation resistor is bridged between the first micro-strip four-mode resonator and the third micro-strip four-mode resonator, and the second isolation resistor is bridged between the second micro-strip four-mode resonator and the fourth micro-strip four-mode resonator. Good output port isolation is achieved, good frequency table selectivity is achieved, the output ports are highly isolated, insertion loss is small, the structure is compact, production cost is low, and the filter is suitable for a modern wireless communication radio frequency front-end circuit system.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency front-end passive devices, and in particular to a four-passband power division filter based on a microstrip line four-mode resonator. Background Art

[0002] With the further development of science and technology, wireless terminal devices emerge in an endless stream, communication system standards become more complex, and available spectrum resources become increasingly tight, resulting in an increasingly complex modern electromagnetic environment and increasingly serious frequency congestion. As an important part of modern wireless communication systems, RF front-end circuits need to develop in the direction of miniaturization, integration, and high performance. In traditional RF front-end circuits, filters and power dividers are usually designed and formed separately, and then the two devices are simultaneously applied to the system in a cascaded manner. However, due to the existence of matching circuits, the cascade design will not only increase the insertion loss of the system, cause mismatch problems to deteriorate system performance, but also cause the overall size of the system to be larger, increasing costs. The power divider filter that integrates power distribution and frequency selection functions as a single modular circuit can not only reduce losses, but also avoid a series of problems caused by the cascade of multiple functional devices, thereby improving the overall performance of the system. There is no need to add matching circuits inside the system, which can significantly reduce the size of the system and reduce costs. It has been widely studied in recent years.

[0003] Reference 1 [Kwok-Keung M.Cheng, Fai-Leung Wong. “A new Wilkinson powerdivider design for dual band application” IEEE Microwave and Wireless Components Letters, vol.17, no.9, pp.664-666.2007], through two quarter-wavelength branch lines and an isolation resistor with a resistance of 100Ω, a power divider operating at 1GHz and 2.6GHz was realized using a simple transmission line structure. However, due to the single function of the circuit, the lack of filtering characteristics and the large size of the circuit, the power divider has not been widely used in practice.

[0004] Reference 2 [Lakshman Athukorala, Djuradj Budimir. "Design of compact dual-mode microstrip filters". IEEE Transactions on Microwave Theory and Techniques, vol. 58, no. 11, pp. 2888-2895, 2010], designed a novel dual-mode filter through a compact open-loop dual-mode resonator, and achieved a bandpass filter response with a center frequency of 1.5 GHz without using a non-resonant unit. However, since the device circuit does not have a power distribution function and only has a single-passband filter response, this filter has not been widely used in practice.

[0005] Reference 3 [He Zhu, Amin M. Abbosh, Lei Guo. “Wideband four-way filtering power divider with sharp selectivity and wide stopband using looped coupled-line structures”. IEEE Microwave and Wireless Components Letters, vol. 26, no. 6, pp. 413-415, 2016], through the terminal short-circuit branch, the ring coupled line structure and the connecting line structure, the stopband high harmonic suppression effect and excellent passband response are achieved, and the input power is equally divided into four outputs using two ring coupled line structures. Although the device has both power distribution and frequency filtering response characteristics, it has only one frequency selective passband, and the circuit structure is not compact enough and the size is large, which is not conducive to the miniaturization of highly integrated RF front-end systems.

[0006] Chinese patent document CN110429363B discloses a three-passband power division filter based on a multi-mode fork resonator. The filter uses a parallel coupled line structure and reasonably distributes the odd and even modes of the three-mode fork resonator to achieve a good three-passband frequency filtering response and power distribution function. Although the device has power distribution and three-passband frequency filtering response characteristics, the number of frequency response passbands of this device is only 3, which has limitations in use in multi-frequency system mode operation. The two isolation resistors used by this device to achieve output port isolation have large resistance values. In actual use, not only is the overall energy consumption of the circuit large, but the heat generated by the resistor is also high, which may cause the resistor to overheat or even be damaged. It has certain limitations in working in high temperature environments. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, an object of the present invention is to provide a four-passband power splitter filter based on a microstrip line four-mode resonator.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A four-passband power splitter based on a microstrip line four-mode resonator comprises a dielectric substrate; a metal grounding plate is provided on the bottom surface of the dielectric substrate, and a central input port feeder, a first output feeder, a second output feeder, four microstrip four-mode resonators and two isolation resistors are provided on the top surface of the dielectric substrate. The central input port feeder is located at the longitudinal midline of the dielectric substrate, and the first output feeder and the second output feeder are respectively arranged on both sides of the central input port feeder in a mirror-symmetrical manner. A first microstrip four-mode resonator and a second microstrip four-mode resonator are respectively arranged between the central input port feeder and the first output feeder; a third microstrip four-mode resonator and a fourth microstrip four-mode resonator are respectively arranged between the central input port feeder and the second output feeder.

[0010] The four microstrip four-mode resonators are respectively microstrip four-mode resonator No. 1, microstrip four-mode resonator No. 2, microstrip four-mode resonator No. 3 and microstrip four-mode resonator No. 4; the microstrip four-mode resonator No. 1 and the microstrip four-mode resonator No. 2 are arranged between the central input port feeder and the first output feeder; the microstrip four-mode resonator No. 3 and the microstrip four-mode resonator No. 4 are arranged between the central input port feeder and the second output feeder.

[0011] The isolation resistor includes a first isolation resistor and a second isolation resistor; the first isolation resistor is connected between the first microstrip four-mode resonator and the third microstrip four-mode resonator; the second isolation resistor is connected between the second microstrip four-mode resonator and the fourth microstrip four-mode resonator.

[0012] Preferably according to the present invention, the central input port feeder includes a first 50 ohm microstrip line guide and an input three-wire coupling line; one end of the first 50 ohm microstrip line guide is close to the first side of the dielectric substrate, and the other end is connected to the input three-wire coupling line; the connection between the first 50 ohm microstrip line guide and the first side of the dielectric substrate is the input end.

[0013] Preferably, according to the present invention, the first output feeder line includes a second 50 ohm microstrip line guide and an L-shaped output two-wire coupling line; the second 50 ohm microstrip line guide is close to the second side of the dielectric substrate, the L-shaped output coupling line is connected to the second 50 ohm microstrip line guide, the L-shaped output two-wire coupling line is parallel to the input three-wire coupling line, and the second 50 ohm microstrip line guide is perpendicular to the input three-wire coupling line. The connection between the 50 ohm microstrip line guide and the second side of the dielectric substrate is the first output end.

[0014] Preferably according to the present invention, the second output feeder line includes a third 50 ohm microstrip line guide strip and an L-shaped output two-wire coupled line; the third 50 ohm microstrip line guide strip is close to the third side of the dielectric substrate, the L-shaped output two-wire coupled line is connected to the third 50 ohm microstrip line guide strip, the L-shaped output two-wire coupled line is parallel to the input three-wire coupled line, and the third 50 ohm microstrip line guide strip is perpendicular to the input three-wire coupled line; the connection between the 50 ohm microstrip line guide strip and the third side of the dielectric substrate is the second output end.

[0015] Preferably according to the present invention, the first microstrip four-mode resonator includes a first terminal open-circuit branch A, a second terminal open-circuit branch A, a third terminal open-circuit branch A, a fourth terminal open-circuit branch A, a fifth terminal open-circuit branch A and a microstrip connecting line A. The two ends of the microstrip connecting line A are respectively vertically connected to the first terminal open branch A and the second terminal open branch A on the same side; the first terminal open branch A and the second terminal open branch A are mirror-symmetrical about the fifth terminal open branch A; the third terminal open branch A and the fourth terminal open branch A are mirror-symmetrical about the fifth terminal open branch A; the third terminal open branch A and the fourth terminal open branch A are both vertically connected to the microstrip connecting line A on the same side; the fifth terminal open branch A is vertically connected to the first terminal open branch A and the second terminal open branch A; the microstrip connecting line A, the third terminal open branch A, the fourth terminal open branch A and the fifth terminal open branch A are all located on the same side of the first terminal open branch A and the second terminal open branch A.

[0016] Preferably according to the present invention, the second microstrip four-mode resonator includes a first terminal open branch B, a second terminal open branch B, a third terminal open branch B, a fourth terminal open branch B, a fifth terminal open branch B and a microstrip connecting line B; the two ends of the microstrip connecting line B are respectively vertically connected to the first terminal open branch B and the second terminal open branch B on the same side; the first terminal open branch B and the second terminal open branch B are mirror-symmetrical about the fifth terminal open branch B; the third terminal open branch B and the fourth terminal open branch B are mirror-symmetrical about the fifth terminal open branch B; the third terminal open branch B and the fourth terminal open branch B are both vertically connected to the microstrip connecting line B on the same side; the fifth terminal open branch B is vertically connected to the first terminal open branch B and the second terminal open branch B; the microstrip connecting line B, the third terminal open branch B, the fourth terminal open branch B and the fifth terminal open branch B are all located on the same side of the first terminal open branch B and the second terminal open branch B.

[0017] Preferably according to the present invention, the third microstrip four-mode resonator includes a first terminal open branch C, a second terminal open branch C, a third terminal open branch C, a fourth terminal open branch C, a fifth terminal open branch C and a microstrip connecting line C; the two ends of the microstrip connecting line C are respectively vertically connected to the first terminal open branch C and the second terminal open branch C on the same side; the first terminal open branch C and the second terminal open branch C are mirror-symmetrical about the fifth terminal open branch C; the third terminal open branch C and the fourth terminal open branch C are mirror-symmetrical about the fifth terminal open branch C; the third terminal open branch C and the fourth terminal open branch C are both vertically connected to the microstrip connecting line C on the same side; the fifth terminal open branch C is vertically connected to the first terminal open branch C and the second terminal open branch C; the microstrip connecting line C, the third terminal open branch C, the fourth terminal open branch C and the fifth terminal open branch C are all located on the same side of the first terminal open branch C and the second terminal open branch C.

[0018] Preferably according to the present invention, the fourth microstrip four-mode resonator includes a first terminal open branch D, a second terminal open branch D, a third terminal open branch D, a fourth terminal open branch D, a fifth terminal open branch D and a microstrip connecting line D; the two ends of the microstrip connecting line D are respectively vertically connected to the first terminal open branch D and the second terminal open branch D on the same side; the first terminal open branch D and the second terminal open branch D are mirror-symmetrical about the fifth terminal open branch D; the third terminal open branch D and the fourth terminal open branch D are mirror-symmetrical about the fifth terminal open branch D; the third terminal open branch D and the fourth terminal open branch D are both vertically connected to the microstrip connecting line D on the same side; the fifth terminal open branch D is vertically connected to the first terminal open branch D and the second terminal open branch D; the microstrip connecting line D, the third terminal open branch D, the fourth terminal open branch D and the fifth terminal open branch D are all located on the same side of the first terminal open branch D and the second terminal open branch D.

[0019] Preferably, according to the present invention, microstrip four-mode resonator No. 1 and microstrip four-mode resonator No. 2 are mirror-symmetrical on both sides of the input three-wire coupling line; microstrip four-mode resonator No. 3 and microstrip four-mode resonator No. 4 are mirror-symmetrical on both sides of the input three-wire coupling line; microstrip four-mode resonator No. 1 and microstrip four-mode resonator No. 4 are centrally symmetrically arranged; microstrip four-mode resonator No. 2 and microstrip four-mode resonator No. 3 are centrally symmetrically arranged.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] In the circuit processing technology, the present invention can be realized by etching the designed compact circuit metal structure on an independent printed circuit board, which has low process requirements for circuit processing manufacturers and low production costs. At the same time, the present invention transmits signals through two-wire coupling and three-wire coupling, reasonably distributes the odd and even modes of the four microstrip four-mode resonators, and the characteristics of the open branches in the microstrip four-mode resonators to generate frequency response transmission zeros, thereby achieving excellent four-passband frequency selection characteristics and power distribution characteristics, and respectively bridges isolation resistors between two pairs of microstrip four-mode resonators to achieve good output port isolation. The four-passband power divider filter described in the present invention has good frequency table selectivity, high isolation of the output port, low insertion loss, compact structure, and low production cost, and is suitable for modern wireless communication radio frequency front-end circuit systems.

[0022] (2) Chinese patent document CN110429363B discloses a three-passband power splitter filter based on a multi-mode fork resonator, but the frequency response passband number of the device disclosed in the patent document is only 3, and the operating frequencies are 1.53 GHz, 2.0 GHz, and 2.36 GHz. The device has limitations in use in a multi-frequency system mode working environment. The frequency response passband number of a four-passband power splitter filter based on a microstrip multi-mode resonator proposed in the present invention is 4, and the operating frequencies are 1.25 GHz, 1.68 GHz, 1.83 GHz, and 2.2 GHz, respectively, which are different from the operating frequencies of the device disclosed in Chinese patent document CN110429363B. In a multi-frequency system mode working environment, in order to achieve a four-passband frequency response, a cascade combination of four single-passband filters, or a cascade combination of two dual-passband filters, or a cascade combination of a single-passband filter and a three-passband filter is usually required, which not only increases the overall size of the system and reduces performance, but also increases the circuit production cost. The present invention proposes a four-passband power splitter filter based on a microstrip multimode resonator. An independent device of this type can meet the needs of the four-passband frequency response in the multi-frequency system mode. It is more superior than the device disclosed in the Chinese patent document CN110429363B. It not only reduces the circuit size and the production cost of the circuit, but also avoids the problem of increased circuit insertion loss caused by the cascade combination of multiple filters. In addition, in order to achieve good output port isolation, the two isolation resistors in the device disclosed in the Chinese patent document CN110429363B have a resistance of 2500Ω and 5000Ω, respectively, which are relatively large. In actual use, a resistor with a larger resistance value will not only increase the overall energy consumption of the circuit, but also generate more heat, which may cause the resistor to overheat or even be damaged, and has certain limitations when working in a high temperature environment. The two isolation resistors in the four-passband power splitter filter based on the microstrip multimode resonator proposed by the present invention have resistance values ​​of only 200Ω and 310Ω, which are more than 10 times different from the resistance values ​​of the two isolation resistors used in the device disclosed in the Chinese patent document CN110429363B. The filter has better tolerance and stability when working in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional structural schematic diagram of a four-passband power division filter based on a microstrip line four-mode resonator in the present invention;

[0024] Figure 2 It is a front view of a three-dimensional structural schematic diagram of a four-passband power division filter based on a microstrip line four-mode resonator in the present invention;

[0025] Figure 3 It is a schematic diagram of the structure and size of a three-dimensional schematic diagram of a four-passband power division filter based on a microstrip line four-mode resonator in the present invention;

[0026] Figure 4 It is a frequency response characteristic S parameter simulation diagram of the four-passband power division filter based on the microstrip line four-mode resonator in the present invention;

[0027] Figure 5 It is an S parameter simulation diagram of the matching characteristics and isolation characteristics of two output ports of the four-passband power division filter based on the microstrip line four-mode resonator in the present invention.

[0028] in:

[0029] 1. Central input port feeder, 2. First output feeder, 3. Second output feeder, 4. Microstrip four-mode resonator No. 1, 41. First terminal open branch A, 42. Second terminal open branch A, 43. Microstrip connecting line A, 44. Third terminal open branch A, 45. Fourth terminal open branch A, 46. Fifth terminal open branch A, 5. Microstrip four-mode resonator No. 2, 51. First terminal open branch B, 52. Second terminal open branch B, 53. Microstrip connecting line B, 54. Third terminal open branch B, 55. Fourth terminal open branch B, 56. Fifth terminal open branch B, 6. Third Microstrip four-mode resonator No. 4, 61, the first terminal open branch C, 62, the second terminal open branch C, 63, the microstrip connecting line C, 64, the third terminal open branch C, 65, the fourth terminal open branch C, 66, the fifth terminal open branch C, 7, microstrip four-mode resonator No. 4, 71, the first terminal open branch D, 72, the second terminal open branch D, 73, the microstrip connecting line D, 74, the third terminal open branch D, 75, the fourth terminal open branch D, 76, the fifth terminal open branch D, 8, the metal ground plate, 9, the dielectric substrate, R1, the first isolation resistor, R2, the second isolation resistor. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings:

[0031] like Figure 1 A four-passband power division filter based on a microstrip line four-mode resonator is shown, and the four-passband power division filter includes a dielectric substrate 9. A metal grounding plate 8 is provided on the bottom surface of the dielectric substrate 9, and a central input port feeder 1, a first output feeder 2, and a second output feeder 3 are provided on the top surface of the dielectric substrate 9, wherein the central input port feeder 1 is located at the longitudinal midline position of the dielectric substrate 9, and the first output feeder 2 and the second output feeder 3 are respectively arranged on both sides of the central input port feeder 1 in a mirror-symmetrical manner; a first microstrip four-mode resonator 4 and a second microstrip four-mode resonator 5 are respectively provided between the central input port feeder 1 and the first output feeder 2; and a third microstrip four-mode resonator 5 and a fourth microstrip four-mode resonator 7 are respectively provided between the central input port feeder 1 and the second output feeder 3.

[0032] In the four-passband power division filter based on the microstrip line four-mode resonator described in the present invention, the central input port feeder 1, the first output feeder 2, the second output feeder 3 and the four microstrip four-mode resonators have a compact structure in terms of structural layout. In actual circuit processing, they can be etched on an independent printed circuit board, and the process requirements for circuit processing manufacturers are low.

[0033] The present invention utilizes two-wire coupling and three-wire coupling for signal transmission, reasonably distributes the odd and even modes of four microstrip four-mode resonators, and the characteristics of open-circuit branches in the microstrip four-mode resonators generating frequency response transmission zeros, thereby achieving excellent four-passband frequency selection characteristics and power distribution characteristics, and respectively bridges isolation resistors between two pairs of microstrip four-mode resonators to achieve good output port isolation. The present invention has good frequency table selectivity, high isolation of the output port, small insertion loss, compact structure, and low production cost, and is suitable for modern wireless communication radio frequency front-end circuit systems.

[0034] like Figure 1 and Figure 2 As shown, the central input port feed line 1 includes a first 50-ohm microstrip line guide 11 and an input three-wire coupling line 12. One end of the first 50-ohm microstrip line guide 11 is close to the first side 9a of the dielectric substrate 9, and the other end is connected to the input three-wire coupling line 12; the connection between the first 50-ohm microstrip line guide 11 and the first side 9a of the dielectric substrate 9 is the input end.

[0035] like Figure 1 and Figure 2 As shown, the first output feed line 2 is composed of a second 50-ohm microstrip line guide strip 21 and an L-shaped output two-wire coupling line 22. The second 50-ohm microstrip line guide strip 21 is close to the second side edge 9b of the dielectric substrate 9. The L-shaped output coupling line 22 is connected to the second 50-ohm microstrip line guide strip 21. The L-shaped output two-wire coupling line 22 is parallel to the input three-wire coupling line 12. The second 50-ohm microstrip line guide strip 21 is perpendicular to the input three-wire coupling line 12. The connection between the 50-ohm microstrip line guide strip 21 and the second side edge 9b of the dielectric substrate 9 is the first output end.

[0036] like Figure 1 and Figure 2 As shown, the second output feed line 3 is composed of a third 50-ohm microstrip line guide strip 31 and an L-shaped output two-wire coupling line 32. The third 50-ohm microstrip line guide strip 31 is close to the third side 9c of the dielectric substrate 9, the L-shaped output two-wire coupling line 32 is connected to the third 50-ohm microstrip line guide strip 31, the L-shaped output two-wire coupling line 32 is parallel to the input three-wire coupling line 12, and the third 50-ohm microstrip line guide strip 31 is perpendicular to the input three-wire coupling line 12; the connection between the 50-ohm microstrip line guide strip 31 and the third side 9c of the dielectric substrate 9 is the second output end.

[0037] The present invention utilizes the electric field distribution characteristics of four microstrip four-mode resonators with the same structure and the central input port feeder 1, performs signal transmission through two-wire coupling and three-wire coupling, reasonably distributes the odd and even modes of the four microstrip four-mode resonators, and the characteristics of the open-circuit branches in the microstrip four-mode resonators generating frequency response transmission zero points, thereby achieving excellent four-passband frequency selection characteristics and power distribution characteristics. The four-passband power division filter of the present invention utilizes isolation resistors connected across two pairs of microstrip four-mode resonators to achieve good output port isolation.

[0038] like Figure 1 and Figure 2 As shown, the first microstrip four-mode resonator 4 includes a first terminal open branch A41, a second terminal open branch A42, a third terminal open branch A44, a fourth terminal open branch A45, a fifth terminal open branch A46 and a microstrip connecting line A43; the two ends of the microstrip connecting line A43 are respectively vertically connected to the first terminal open branch A41 and the second terminal open branch A42 on the same side; the first terminal open branch A41 and the second terminal open branch A42 are mirror-symmetrical about the fifth terminal open branch A46; the third terminal open branch A44 and the fourth terminal open branch A45 are mirror-symmetrical about the fifth terminal open branch A46; The four-terminal open branch A45 is mirror-symmetrical about the fifth terminal open branch 46; the third terminal open branch A44 and the fourth terminal open branch A45 are both vertically connected to the microstrip connecting line A43 on the same side; the fifth terminal open branch A46 is vertically connected to the first terminal open branch A41 and the second terminal open branch A42; the microstrip connecting line A43, the third terminal open branch A44, the fourth terminal open branch A45 and the fifth terminal open branch A46 are all located on the same side of the first terminal open branch A41 and the second terminal open branch A42.

[0039] like Figure 1 and Figure 2As shown, the second microstrip four-mode resonator 5 includes a first terminal open branch B51, a second terminal open branch B52, a third terminal open branch B54, a fourth terminal open branch B55, a fifth terminal open branch B56 and a microstrip connecting line B53; the two ends of the microstrip connecting line B53 are respectively vertically connected to the first terminal open branch B51 and the second terminal open branch B52 on the same side; the first terminal open branch B51 and the second terminal open branch B52 are mirror-symmetrical about the fifth terminal open branch B56; the third terminal open branch B54 and the fourth terminal open branch B5 .... The four-terminal open branch B55 is mirror-symmetrical about the fifth terminal open branch B56; the third terminal open branch B54 and the fourth terminal open branch B55 are both vertically connected to the microstrip connecting line B53 on the same side; the fifth terminal open branch B56 is vertically connected to the first terminal open branch B51 and the second terminal open branch B52; the microstrip connecting line B53, the third terminal open branch B54, the fourth terminal open branch B55 and the fifth terminal open branch B56 are all located on the same side of the first terminal open branch B51 and the second terminal open branch B52.

[0040] like Figure 1 and Figure 2 As shown, the third microstrip four-mode resonator 6 includes a first terminal open branch C61, a second terminal open branch C62, a third terminal open branch C64, a fourth terminal open branch C65, a fifth terminal open branch C66 and a microstrip connecting line C63; the two ends of the microstrip connecting line C63 are respectively vertically connected to the first terminal open branch C61 and the second terminal open branch C62 on the same side; the first terminal open branch C61 and the second terminal open branch C62 are mirror-symmetrical about the fifth terminal open branch C66; the third terminal open branch C64 and the fourth terminal open branch C65 are respectively .... The four-terminal open branch C65 is mirror-symmetric with respect to the fifth terminal open branch C66; the third terminal open branch C64 and the fourth terminal open branch C65 are both vertically connected to the microstrip connecting line C63 on the same side; the fifth terminal open branch C66 is vertically connected to the first terminal open branch C61 and the second terminal open branch C62; the microstrip connecting line C63, the third terminal open branch C64, the fourth terminal open branch C65 and the fifth terminal open branch C66 are all located on the same side of the first terminal open branch C61 and the second terminal open branch C62.

[0041] like Figure 1 and Figure 2As shown, the fourth microstrip four-mode resonator 7 includes a first terminal open branch D71, a second terminal open branch D72, a third terminal open branch D74, a fourth terminal open branch D75, a fifth terminal open branch D76 and a microstrip connecting line D73; the two ends of the microstrip connecting line D73 are respectively vertically connected to the first terminal open branch D71 and the second terminal open branch D72 on the same side; the first terminal open branch D71 and the second terminal open branch D72 are mirror-symmetrical about the fifth terminal open branch D76; the third terminal open branch D74 and the fourth terminal open branch D75 are respectively .... The four-terminal open branch D75 is mirror-symmetric about the fifth terminal open branch D76; the third terminal open branch D74 and the fourth terminal open branch D75 are both vertically connected to the microstrip connection line D73 on the same side; the fifth terminal open branch D76 is vertically connected to the first terminal open branch D71 and the second terminal open branch D72; the microstrip connection line D73, the third terminal open branch D74, the fourth terminal open branch D75 and the fifth terminal open branch D76 are all located on the same side of the first terminal open branch D71 and the second terminal open branch D72.

[0042] like Figure 1 and Figure 2 As shown, the first microstrip four-mode resonator 4 and the second microstrip four-mode resonator 5 are mirror-symmetrical on both sides of the input three-wire coupling line 12; the third microstrip four-mode resonator 6 and the fourth microstrip four-mode resonator 7 are mirror-symmetrical on both sides of the input three-wire coupling line 12; the first microstrip four-mode resonator 4 and the fourth microstrip four-mode resonator 7 are centrally symmetrically arranged; the second microstrip four-mode resonator 5 and the third microstrip four-mode resonator 6 are centrally symmetrically arranged.

[0043] The front view of the four-passband power splitter based on microstrip line multimode resonator described in the present invention is as follows Figure 2 As shown, the relevant size specifications are as follows Figure 3 The dielectric substrate 7 used in the present invention has a relative dielectric constant of 3.55, a thickness of 0.508 mm, and a loss tangent of 0.0027. Figure 3 , the size parameters of the power splitter filter are as follows: W1 = 0.26mm, W2 = 0.32mm, W3 = 0.22mm, W4 = 0.9mm, W5 = 0.9mm, L1 = 5mm, L2 = 0.4mm, L3 = 25.4mm, L4 = 24.33mm, L5 = 16.46mm, L6 = 12.32mm, L7 = 6.67mm, L8 = 14.1mm, L9 = 6.76mm, L 10 =0.6mm, g1=0.16mm, g2=0.1mm, R1=310Ω, R2=200Ω.

[0044] The four-pass band power divider filter in this example is modeled and simulated in the electromagnetic simulation software HFSS.13.0. Figure 4 It is the frequency response characteristic S parameter simulation diagram of the four-pass band power divider filter in the present invention, from Figure 4 It can be seen that the center frequencies of the four passbands of the four-passband power divider filter are 1.25GHz, 1.68GHz, 1.83GHz, and 2.2GHz, the return loss in the passband is less than 16.3dB, and the minimum insertion loss is 1.3dB. There are 6 transmission zeros outside the passband, which makes the four-passband power divider filter in this example have good frequency selectivity and out-of-band harmonic suppression.

[0045] Figure 5 is an S parameter simulation diagram of the matching characteristics and isolation characteristics of the two power output ports of the four-passband power splitter in the present invention, from Figure 5 It can be seen that the output port return loss within the passband of the four-passband power divider filter in this example is lower than 11.9dB, and the isolation within the passband is better than 15.1dB.

[0046] The present invention can etch the designed compact circuit metal structure on an independent printed circuit board in the circuit processing technology, which can be realized by etching on the independent printed circuit board, and has low process requirements for circuit processing manufacturers and low production costs. At the same time, signal transmission is carried out through two-wire coupling and three-wire coupling, and the odd and even modes of four microstrip four-mode resonators are reasonably distributed, and the characteristics of the frequency response transmission zero point generated by the open-circuit branches in the microstrip four-mode resonator are realized, so as to realize excellent four-band frequency selection characteristics and power distribution characteristics, and isolation resistors are respectively connected between two pairs of microstrip four-mode resonators to realize good output port isolation.

[0047] Since the four-passband power splitter filter of the present invention has good frequency table selectivity, high isolation of output ports, low insertion loss, compact structure, and low production cost, it is suitable for modern wireless communication radio frequency front-end circuit systems. The present invention uses two-wire coupling and three-wire coupling for signal transmission, reasonably distributes the odd and even modes of four microstrip four-mode resonators, and the characteristics of open branches in the microstrip four-mode resonators to generate frequency response transmission zeros, realizes excellent four-passband frequency selection characteristics and power distribution characteristics, and bridges isolation resistors between two pairs of microstrip four-mode resonators to achieve good output port isolation. The present invention has good frequency table selectivity, high isolation of output ports, low insertion loss, compact structure, and low production cost, and is suitable for modern wireless communication radio frequency front-end circuit systems.

[0048] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the scope of protection determined by the claims of the present invention.

Claims

1. A four-passband power splitter filter based on a microstrip line multimode resonator, characterized in that: The four-passband power division filter comprises a dielectric substrate (9); a metal grounding plate (8) is provided on the bottom surface of the dielectric substrate (9), and a central input port feeder (1), a first output feeder (2), a second output feeder (3), four microstrip four-mode resonators and two isolation resistors are provided on the top surface; wherein the central input port feeder (1) is located at the longitudinal midline position of the dielectric substrate (9), and the first output feeder (2) and the second output feeder (3) are respectively arranged on both sides of the central input port feeder (1) in a mirror-symmetrical manner; The four microstrip four-mode resonators are respectively a first microstrip four-mode resonator (4), a second microstrip four-mode resonator (5), a third microstrip four-mode resonator (6) and a fourth microstrip four-mode resonator (7); the first microstrip four-mode resonator (4) and the second microstrip four-mode resonator (5) are arranged between the central input port feeder (1) and the first output feeder (2); the third microstrip four-mode resonator (6) and the fourth microstrip four-mode resonator (7) are arranged between the central input port feeder (1) and the second output feeder (3); The isolation resistor comprises a first isolation resistor and a second isolation resistor; the first isolation resistor is connected between the first microstrip four-mode resonator (4) and the third microstrip four-mode resonator (6); and the second isolation resistor is connected between the second microstrip four-mode resonator (5) and the fourth microstrip four-mode resonator (7).

2. The four-passband power splitter filter based on the microstrip line four-mode resonator according to claim 1, characterized in that: The central input port feed line (1) comprises a first 50-ohm microstrip line guide strip (11) and an input three-wire coupling line (12); one end of the first 50-ohm microstrip line guide strip (11) is close to the first side edge (9a) of the dielectric substrate (9), and the other end is connected to the input three-wire coupling line (12); the connection between the first 50-ohm microstrip line guide strip (11) and the first side edge (9a) of the dielectric substrate (9) is the input end.

3. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The first output feed line (2) comprises a second 50-ohm microstrip line guide strip (21) and an L-shaped output two-wire coupling line (22); the second 50-ohm microstrip line guide strip (21) is close to the second side edge (9b) of the dielectric substrate (9), the L-shaped output coupling line (22) is connected to the second 50-ohm microstrip line guide strip (21), the L-shaped output two-wire coupling line (22) is parallel to the input three-wire coupling line (12), and the second 50-ohm microstrip line guide strip (21) is perpendicular to the input three-wire coupling line (12); the connection point between the 50-ohm microstrip line guide strip (21) and the second side edge (9b) of the dielectric substrate (9) is the first output end.

4. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The second output feed line (3) comprises a third 50-ohm microstrip line guide strip (31) and an L-shaped output two-wire coupling line (32); the third 50-ohm microstrip line guide strip (31) is close to the third side edge (9c) of the dielectric substrate (9); the L-shaped output two-wire coupling line (32) is connected to the third 50-ohm microstrip line guide strip (31); the L-shaped output two-wire coupling line (32) is parallel to the input three-wire coupling line (12); the third 50-ohm microstrip line guide strip (31) is perpendicular to the input three-wire coupling line (12); the connection point between the 50-ohm microstrip line guide strip (31) and the third side edge (9c) of the dielectric substrate (9) is the second output end.

5. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The first microstrip four-mode resonator (4) comprises a first terminal open-circuit branch A (41), a second terminal open-circuit branch A (42), a third terminal open-circuit branch A (44), a fourth terminal open-circuit branch A (45), a fifth terminal open-circuit branch A (46) and a microstrip connecting line A (43); Two ends of the microstrip connecting line A (43) are respectively vertically connected to the first terminal open-circuit branch node A (41) and the second terminal open-circuit branch node A (42) on the same side; The first terminal open-circuit branch A (41) and the second terminal open-circuit branch A (42) are mirror-symmetrical with respect to the fifth terminal open-circuit branch A (46); The third terminal open-circuit branch A (44) and the fourth terminal open-circuit branch A (45) are mirror-symmetrical with respect to the fifth terminal open-circuit branch A (46); The third terminal open-circuit branch node A (44) and the fourth terminal open-circuit branch node A (45) are both vertically connected to the microstrip connection line A (43) on the same side; The fifth terminal open-circuit branch A (46) is vertically connected to the first terminal open-circuit branch A (41) and the second terminal open-circuit branch A (42); The microstrip connecting line A (43), the third terminal open-circuit branch A (44), the fourth terminal open-circuit branch A (45) and the fifth terminal open-circuit branch A (46) are all located on the same side of the first terminal open-circuit branch A (41) and the second terminal open-circuit branch A (42).

6. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The second microstrip four-mode resonator (5) comprises a first terminal open-circuit branch B (51), a second terminal open-circuit branch B (52), a third terminal open-circuit branch B (54), a fourth terminal open-circuit branch B (55), a fifth terminal open-circuit branch B (56) and a microstrip connecting line B (53); Two ends of the microstrip connecting line B (53) are respectively vertically connected to the first terminal open-circuit branch node B (51) and the second terminal open-circuit branch node B (52) on the same side; The first terminal open-circuit branch B (51) and the second terminal open-circuit branch B (52) are mirror-symmetrical with respect to the fifth terminal open-circuit branch B (56); The third terminal open-circuit branch B (54) and the fourth terminal open-circuit branch B (55) are mirror-symmetrical with respect to the fifth terminal open-circuit branch B (56); The third terminal open-circuit branch node B (54) and the fourth terminal open-circuit branch node B (55) are both vertically connected to the microstrip connection line B (53) on the same side; The fifth terminal open branch B (56) is vertically connected to the first terminal open branch B (51) and the second terminal open branch B (52); The microstrip connecting line B (53), the third terminal open-circuit branch node B (54), the fourth terminal open-circuit branch node B (55) and the fifth terminal open-circuit branch node B (56) are all located on the same side of the first terminal open-circuit branch node B (51) and the second terminal open-circuit branch node B (52).

7. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The third microstrip four-mode resonator C (6) comprises a first terminal open-circuit branch C (61), a second terminal open-circuit branch C (62), a third terminal open-circuit branch C (64), a fourth terminal open-circuit branch C (65), a fifth terminal open-circuit branch C (66) and a microstrip connecting line C (63); Two ends of the microstrip connection line C (63) are respectively vertically connected to the first terminal open-circuit branch node C (61) and the second terminal open-circuit branch node C (62) on the same side; The first terminal open-circuit branch C (61) and the second terminal open-circuit branch C (62) are mirror-symmetrical with respect to the fifth terminal open-circuit branch C (66); The third terminal open-circuit branch C (64) and the fourth terminal open-circuit branch C (65) are mirror-symmetrical with respect to the fifth terminal open-circuit branch C (66); The third terminal open-circuit branch node C (64) and the fourth terminal open-circuit branch node C (65) are both vertically connected to the microstrip connection line C (63) on the same side; The fifth terminal open branch node C (66) is vertically connected to the first terminal open branch node C (61) and the second terminal open branch node C (62); The microstrip connecting line C (63), the third terminal open-circuit branch C (64), the fourth terminal open-circuit branch C (65) and the fifth terminal open-circuit branch C (66) are all located on the same side of the first terminal open-circuit branch C (61) and the second terminal open-circuit branch C (62).

8. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The fourth microstrip four-mode resonator (7) comprises a first terminal open-circuit branch D (71), a second terminal open-circuit branch D (72), a third terminal open-circuit branch D (74), a fourth terminal open-circuit branch D (75), a fifth terminal open-circuit branch D (76) and a microstrip connecting line D (73); Two ends of the microstrip connecting line D (73) are respectively vertically connected to the first terminal open-circuit branch node D (71) and the second terminal open-circuit branch node D (72) on the same side; The first terminal open-circuit branch D (71) and the second terminal open-circuit branch D (72) are mirror-symmetrical with respect to the fifth terminal open-circuit branch D (76); The third terminal open-circuit branch D (74) and the fourth terminal open-circuit branch D (75) are mirror-symmetrical with respect to the fifth terminal open-circuit branch D (76); The third terminal open-circuit branch node D (74) and the fourth terminal open-circuit branch node D (75) are both vertically connected to the microstrip connection line D (73) on the same side; The fifth terminal open branch D (76) is vertically connected to the first terminal open branch D (71) and the second terminal open branch D (72); The microstrip connecting line D (73), the third terminal open branch D (74), the fourth terminal open branch D (75) and the fifth terminal open branch D (76) are all located on the same side of the first terminal open branch D (71) and the second terminal open branch D (72).

9. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The first microstrip four-mode resonator (4) and the second microstrip four-mode resonator (5) are mirror-symmetrical on both sides of the input three-wire coupling line (12); the third microstrip four-mode resonator (6) and the fourth microstrip four-mode resonator (7) are mirror-symmetrical on both sides of the input three-wire coupling line (12).

10. The four-passband power splitter filter based on microstrip line four-mode resonator according to claim 1, characterized in that: The first microstrip four-mode resonator (4) and the fourth microstrip four-mode resonator (7) are arranged in a central symmetric manner; the numbered microstrip four-mode resonator (5) and the third microstrip four-mode resonator (6) are arranged in a central symmetric manner.

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