A filter power divider based on dielectric resonator

Abstract

The application discloses a filter power divider based on a dielectric resonator and belongs to the technical field of wireless communication. The device is in an axial symmetry structure as a whole and comprises a rectangular dielectric substrate, a microstrip structure arranged on the front surface of the rectangular dielectric substrate, a gasket, a dielectric resonator, an isolation element and a grounding metal plate arranged on the back surface of the rectangular dielectric substrate. The microstrip structure comprises an input microstrip section, an impedance transformation section and an output microstrip section, and the gasket and the dielectric resonator are arranged in the middle of the impedance transformation section and jointly form a filter structure. The dielectric resonator is used to replace the quarter wavelength impedance transformation structure of the Wilkinson power divider, so that the functions of filtering and power dividing can be simultaneously realized, the filter has excellent narrowband frequency selectivity and good isolation degree, and in addition, the central frequency can be adjusted by adjusting the height of the gasket, so that the flexibility is high.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a filter power divider based on a dielectric resonator, which has narrowband frequency selectivity while having a compact structural size. Background Technology

[0002] With the rapid development of modern communication systems, microwave radio frequency circuits are gradually moving towards high performance, miniaturization, and integration. In traditional wireless communication systems, filters and power dividers are typically used as discrete components in microwave radio frequency circuits, cascaded via microstrip transmission lines, which inevitably increases the system size. However, filter power dividers, as functionally integrated devices, can significantly reduce device size and better meet the miniaturization and high performance requirements of communication systems.

[0003] In existing technologies, some scholars have studied the combined filtering and power divider structure. For example, Sai WaiWong et al. designed a filtered power divider by cascading parallel coupling lines at the output of a traditional Wilkinson power divider; however, this cascaded structure offers only a limited reduction in size compared to discrete devices. Yuan Chun Li et al. implemented a filtered power divider by replacing a quarter-wavelength transmission line with a second-order U-shaped resonator filter structure, but its relative bandwidth of 10.1% cannot meet the requirements of some microwave RF circuits.

[0004] Although some filter power dividers have been reported in the literature, these structures cannot simultaneously meet the requirements of narrowband frequency selectivity and miniaturization. Therefore, the fabrication of miniaturized filter power dividers with narrowband filtering is of great significance and has broad application prospects. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art mentioned in the background section by providing a filter power divider based on a dielectric resonator, which can simultaneously perform filtering and power division functions, and has advantages such as excellent narrowband frequency selectivity, small size, low cost, and ease of design.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A filter power divider based on a dielectric resonator has an overall axisymmetric structure, including a rectangular dielectric substrate, a microstrip structure disposed on the front side of the rectangular dielectric substrate, a spacer, a dielectric resonator, an isolation element, and a grounding metal plate disposed on the back side of the rectangular dielectric substrate.

[0008] The microstrip structure includes an input microstrip segment, two impedance transformation segments, and two output microstrip segments.

[0009] The isolation element is a surface-mount resistor R, located between the two output microstrip segments.

[0010] The input microstrip segment includes a first microstrip line, one end of which is located at the edge of a rectangular dielectric substrate as the input terminal, and the other end is connected to two symmetrically arranged impedance transformation segments.

[0011] Both impedance transformation sections include a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, and a seventh microstrip line; one end of the second microstrip line is connected to the first microstrip line, and the other end is connected to the third microstrip line to form an L-shaped structure; the fourth, fifth, sixth, and seventh microstrip lines are connected sequentially, and the fourth microstrip line is arranged parallel to the third microstrip line; the other end of the seventh microstrip line is connected to the output microstrip section.

[0012] The dielectric resonator is a cylindrical structure and is disposed in a rectangular region between the third microstrip line and the fourth microstrip line. A cylindrical spacer is disposed between the dielectric resonator and the rectangular dielectric substrate, and the spacer and the dielectric resonator are concentrically disposed. The third microstrip line, the fourth microstrip line, the spacer and the dielectric resonator together constitute a filter structure.

[0013] Furthermore, the dielectric resonator is spaced at the same distance from the third and fourth microstrip lines.

[0014] Furthermore, the output microstrip segment is a 50-ohm bent microstrip line, with one end located at the edge of a rectangular dielectric substrate, serving as the output terminal.

[0015] Furthermore, the total length of the impedance transformation segment is an odd multiple of a quarter wavelength, and the characteristic impedance is 70.7 ohms.

[0016] Furthermore, the first microstrip line is a 50-ohm transmission line.

[0017] Furthermore, the dielectric material selected for the rectangular dielectric substrate is Rogers RO 4350, with a relative permittivity of 3.66, a loss tangent of 0.004, and a substrate thickness of 0.508 mm.

[0018] Furthermore, the dielectric resonator has a dielectric constant of 36, an unloaded Q value of 3200, a diameter of 5.6 mm, and a height of 2.3 mm.

[0019] Furthermore, the gasket is made of polytetrafluoroethylene, with a relative permittivity of 2.1 and a loss tangent of 0.0002.

[0020] Furthermore, the bends in the transformation segment and the output microstrip segment are chamfered.

[0021] The beneficial effects of this invention are:

[0022] By replacing the quarter-wavelength impedance transformation structure of the Wilkinson power divider with a dielectric resonator, both filtering and power division functions can be achieved simultaneously. This filter-power divider exhibits excellent narrowband frequency selectivity and good isolation. Furthermore, the center frequency can be adjusted by changing the height of the shims, offering high flexibility.

[0023] Compared to devices that directly cascade filters and power dividers, this structure allows for miniaturization and facilitates integration. Furthermore, this invention can be implemented on a single-layer PCB, resulting in a simple structure, low manufacturing cost, and ease of fabrication. Attached Figure Description

[0024] Figure 1 This is an overall structural diagram of the filter power divider based on a dielectric resonator in the embodiment;

[0025] Figure 2 This is a top view of the filter power divider based on a dielectric resonator in the embodiment;

[0026] Figure 3 This is a transmission characteristic curve of a filter power divider based on a dielectric resonator in an embodiment.

[0027] Figure 4 This is a graph showing the output return loss and isolation coefficient of a filter power divider based on a dielectric resonator in an embodiment.

[0028] Explanation of reference numerals: 1. First microstrip line, 2. Second microstrip line, 3. Third microstrip line, 4. Fourth microstrip line, 5. Fifth microstrip line, 6. Sixth microstrip line, 7. Seventh microstrip line, 8. Eighth microstrip line, 9. Ninth microstrip line, 10. Tenth microstrip line, 11. Spacer, 12. Dielectric resonator, 13. Isolation resistor, 14. Dielectric substrate. Detailed Implementation

[0029] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0030] This example provides a filter power divider based on a dielectric resonator, the overall structure of which is as follows: Figure 1 , 2 As shown, the overall structure is axially symmetrical, including a rectangular dielectric substrate, a microstrip structure disposed on the front side of the rectangular dielectric substrate, a pad, a dielectric resonator, an isolation element, and a grounding metal plate disposed on the back side of the rectangular dielectric substrate.

[0031] The rectangular dielectric substrate uses Rogers RO 4350 dielectric material with a relative permittivity of 3.66, a loss tangent of 0.004, and a substrate thickness of 0.508 mm.

[0032] The microstrip structure includes an input microstrip segment, two impedance transformation segments, and two output microstrip segments.

[0033] The isolation element is a surface-mount resistor R, located between the two output microstrip segments.

[0034] The input microstrip segment includes a 50-ohm first microstrip line; one end is located at the edge of a rectangular dielectric substrate as the input end, and the other end is connected to two symmetrical impedance transformation segments.

[0035] The impedance transformation section includes a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, and a seventh microstrip line. One end of the second microstrip line is connected to the first microstrip line, and the other end is connected to the third microstrip line, forming an L-shaped structure. The fourth, fifth, sixth, and seventh microstrip lines are connected sequentially, with the fourth microstrip line parallel to the third microstrip line. The other end of the seventh microstrip line is connected to the output microstrip segment. The total length of the impedance transformation section is an odd multiple of one-quarter of the wavelength, and its characteristic impedance is 70.7 ohms. The third and fourth microstrip lines are 8.8 mm long and 5.6 mm apart.

[0036] The dielectric resonator is a cylindrical structure with a diameter of 5.6 mm and a height of 2.3 mm. Its dielectric constant is 36 and its unloaded Q value is 3200. The dielectric resonator is set in a rectangular area between the third microstrip line and the fourth microstrip line, and the distance between its center and the line connecting the open ends of the third microstrip line and the fourth microstrip line is 3.3 mm.

[0037] A cylindrical spacer with a diameter of 2 mm and a height of 1.2 mm is provided between the dielectric resonator and the rectangular dielectric substrate. The spacer is made of polytetrafluoroethylene with a relative permittivity of 2.1 and a loss tangent of 0.0002. The spacer and the dielectric resonator are concentrically arranged. The third microstrip line, the fourth microstrip line, the spacer and the dielectric resonator together constitute a filter structure.

[0038] Cutting operation at the bends of the microstrip lines in the impedance transformation section and the output microstrip section.

[0039] A dielectric resonator can be viewed as a cylindrical waveguide with open ends, and the lowest-order TE mode is TE0. 01 The dielectric resonator and the microstrip line are magnetically coupled, with one end of the microstrip line open-circuited. To improve the quality factor, a low-loss spacer is added between the dielectric substrate and the resonator. Adjusting the coupling between the dielectric resonator and the microstrip line is achieved by adjusting the spacing between the third and fourth microstrip lines and the height of the spacer.

[0040] Figure 3The simulation and test results are based on the transmission characteristics according to the above embodiments. In the transmission characteristic curve, the horizontal axis represents frequency, and the vertical axis represents the amplitude of the transmission characteristic, in dB. S11 represents the return loss of the filter power divider based on the dielectric resonator; S21 represents the sum of the insertion loss from the first output port to the input port and the 3dB fixed distribution loss when the input port is matched; and S31 represents the sum of the insertion loss from the second output port to the input port and the 3dB fixed distribution loss when the input port is matched. The simulation results show that the center frequency of the passband is 10GHz, the insertion loss at the center frequency is 0.76dB, the input port return loss is 40.55dB, and the 3dB bandwidth is 1.2%.

[0041] Figure 4 The simulation results show the output port return loss and isolation according to the above embodiment. The horizontal axis of the graph represents frequency, and the vertical axis represents the amplitude of the transmission characteristics, in dB. S22 and S33 represent the return loss at the two output ports of the dielectric resonator-based filter power divider, and S23 represents the isolation of the dielectric resonator-based filter power divider. The simulation results show that the output return loss at the center frequency is 16 dB, and the isolation is 18.8 dB.

Claims

1. A dielectric resonator based filtering power divider in an overall axisymmetric structure, characterized by, The application relates to a microstrip filter, which comprises a rectangular dielectric substrate, a microstrip structure arranged on the front surface of the rectangular dielectric substrate, a gasket, a dielectric resonator, a spacer element, and a ground metal plate arranged on the back surface of the rectangular dielectric substrate. The microstrip structure comprises an input microstrip section, two impedance conversion sections, and two output microstrip sections. The spacer element is a patch resistor R arranged between the two output microstrip sections. The input microstrip section comprises a first microstrip line, one end of which is arranged at the edge of the rectangular dielectric substrate as an input end, and the other end of which is connected to two symmetrically arranged impedance conversion sections. The two impedance conversion sections each comprise a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, and a seventh microstrip line; wherein one end of the second microstrip line is connected to the first microstrip line, and the other end of the second microstrip line is connected to the third microstrip line to form an L-shaped structure. The fourth microstrip line, the fifth microstrip line, the sixth microstrip line, and the seventh microstrip line are sequentially connected, and the fourth microstrip line is arranged in parallel with the third microstrip line; the other end of the seventh microstrip line is connected to the output microstrip section. The dielectric resonator is in a cylindrical structure and is arranged in a rectangular region between the third microstrip line and the fourth microstrip line; a cylindrical gasket is arranged between the dielectric resonator and the rectangular dielectric substrate, and the gasket and the dielectric resonator are arranged in a concentric manner; and the third microstrip line, the fourth microstrip line, the gasket, and the dielectric resonator jointly form a filter structure.

2. A dielectric resonator based filter power divider as claimed in claim 1, characterized in that, The dielectric resonator has the same spacing as the third microstrip line and the fourth microstrip line.

3. A dielectric resonator based filter power divider as claimed in claim 2, characterized in that, The output microstrip section is a 50-ohm bent microstrip line, and the other end of the output microstrip section is arranged at the edge of the rectangular dielectric substrate as an output end.

4. A dielectric resonator based filter power divider as claimed in claim 2, characterized in that, The total length of the impedance conversion section is an odd multiple of one-fourth of the wavelength, and the characteristic impedance is 70.7 ohms.

5. A dielectric resonator based filter power divider as claimed in claim 2, wherein, The first microstrip line is a 50-ohm transmission line.

6. A dielectric resonator based filter power divider as claimed in claim 2, wherein, The dielectric material of the rectangular dielectric substrate is Rogers RO 4350, the relative dielectric constant is 3.66, the loss tangent is 0.004, and the thickness of the dielectric substrate is 0.508 mm.

7. A dielectric resonator based filter power divider as claimed in claim 2, wherein, The dielectric constant of the dielectric resonator is 36, the no-load Q value is 3200, the diameter is 5.6 mm, and the height is 2.3 mm.

8. A dielectric resonator based filter power divider as claimed in claim 2, wherein, The material of the gasket is polytetrafluoroethylene, the relative dielectric constant is 2.1, and the loss tangent is 0.0002.

9. A dielectric resonator based filter power divider as claimed in claim 3, wherein, The bent portions of the conversion section and the output microstrip section are chamfered.

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