Dual-passband filtering coupler based on dielectric resonant cavity

Abstract

The invention discloses a dual-passband filtering coupler based on a dielectric resonant cavity, particularly relates to the technical field of wireless communication, and solves the technical problems that in the prior art, a cavity filter and a cavity coupler often work in a cascade mode, and a matching network needs to be additionally configured between the cavity filter and the cavity coupler, so that the hardware cost is high, and the occupied system space is large. According to the technical scheme, the coupler and the dual-passband filter are integrated in one device, the circuit size can be remarkably reduced, and cascade loss between the coupler and the dual-passband filter is eliminated. The high-performance index of the microwave circuit is guaranteed, effective balance between performance and cost is achieved, and the microwave circuit completely conforms to the development direction of miniaturization, high performance and low cost of a future communication system.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication, and particularly relates to a dual-band filtering coupler based on a dielectric resonator. Background Art

[0002] With the rapid development of wireless communication technology, the noise environment is deteriorating continuously and the spectrum resources are becoming increasingly tense. For multi-carrier communication systems, signals of different frequencies need to be transmitted at the same time. Therefore, in order to achieve channel separation and ensure the communication quality of each signal path, various types of dual-band or multi-channel filters are required.

[0003] A coupler is an important component in a radio frequency system. It can realize functions such as signal power distribution and synthesis, signal sampling and monitoring, and has wide applications in fields such as microwave communication, radar detection, and instrument testing. For example, a high-power microwave signal is distributed to multiple antennas or amplifiers; or a part of the small signal is extracted for real-time monitoring without interfering with the transmission of the main signal.

[0004] In modern communication systems, cavity filters and cavity couplers often work in cascade, and a matching network needs to be additionally configured between them. Therefore, the hardware cost is relatively high and the system space occupied is relatively large. At the same time, the cascade between devices will inevitably introduce cascade loss, which also restricts the improvement of system performance to a certain extent. Summary of the Invention

[0005] Therefore, the present invention solves the technical problem that in the prior art, cavity filters and cavity couplers often work in cascade, and a matching network needs to be additionally configured between them, so the hardware cost is relatively high and the system space occupied is relatively large. A dual-band filtering coupler based on a dielectric resonator provided by the present invention integrates a coupler and a dual-band filter in one device through resonator multiplexing technology, which can significantly reduce the circuit volume and eliminate the cascade loss between them. This system-level optimization scheme not only ensures the high-performance indicators of microwave circuits, but also realizes an effective balance between performance and cost, fully meeting the development direction of future communication systems towards miniaturization, high performance, and low cost.

[0006] The present invention provides a dual-band filtering coupler based on a dielectric resonator, which includes a first dielectric cavity and four groups of second dielectric cavities connected to both sides of the first dielectric cavity. The first dielectric cavity contains 4 octagonal (non-regular octagon) dielectric resonators of the same size. Each octagonal dielectric resonator is obtained by cutting off 4 corners of a square dielectric resonator (each corner is cut off an isosceles triangle); the 4 octagonal dielectric resonators are arranged in a 2×2 array, and are coupled to each other through rectangular dielectric sheets, and the widths of the dielectric sheets along the x-axis and y-axis directions are different.

[0007] Furthermore, the outer shapes of the second dielectric cavities are the same, and each is obtained by cutting off a pair of opposite corners from a rectangular dielectric resonator (the cut-off parts are all isosceles triangles, with one angle cut larger and the other angle cut smaller); the first dielectric cavity is coupled to the second dielectric cavities respectively through rectangular dielectric sheets.

[0008] Furthermore, in the middle of each octagonal dielectric resonator in the first dielectric cavity, a pair of differential ports are fixedly arranged up and down. As Figure 1 、 Figure 2 shown, starting from the upper left corner and rotating clockwise, the port order is the input end (differential port 1), the through end (differential port 2), the coupling end (differential port 3), and the isolation end (differential port 4). The input end and the isolation end are on the same side, and the side edges of the resonators excited by both are coupled to a second dielectric cavity (the resonator where the input end is located is coupled to the adjacent second dielectric cavity through a rectangular dielectric sheet, and the resonator where the isolation end is located is coupled to the adjacent second dielectric cavity through a rectangular dielectric sheet). The through end and the coupling end are on the same side, and the side edges of the resonators excited by both are coupled to a second dielectric cavity (the resonator where the through end is located is coupled to the adjacent second dielectric cavity through a rectangular dielectric sheet, and the resonator where the coupling end is located is coupled to the adjacent second dielectric cavity through a rectangular dielectric sheet).

[0009] Furthermore, the dielectric constants of the second dielectric cavities are the same and are significantly greater than the dielectric constant of the first dielectric cavity. The first dielectric cavity is adhesively bonded to the second dielectric cavities around it with glue, the connection contact surfaces are not silver-plated, the contact surface between the first dielectric cavity and the feeding port is not silver-plated, and the remaining surfaces are all silver-plated (that is, all the contact surfaces between the cavities and air are silver-plated).

[0010] In the above technical solution, the technical effects and advantages provided by the present invention are as follows:

[0011] 1. A dual-band filtering coupler based on a dielectric resonator provided by the present invention, through the resonator multiplexing technology, integrates the coupler and the dual-band filter in one device design, which can significantly reduce the circuit volume and eliminate the cascading loss between them. This system-level optimization solution not only ensures the high-performance indicators of the microwave circuit but also realizes an effective balance between performance and cost, fully meeting the development direction of future communication systems towards miniaturization, high performance, and low cost.

[0012] 2. The dual-band filter coupler based on a dielectric resonator provided by the present invention integrates a dual-band filter and a coupler, reuses the dielectric resonator, and realizes differential signal transmission. On the basis of ensuring communication quality and reducing the circuit size, the production cost is effectively reduced; the dual-band differential filter coupler has low insertion loss, good isolation between passbands, and excellent common-mode rejection performance, and has significant advantages in dual-frequency wireless communication systems. Brief Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

[0014] Figure 1 Schematic diagram of the overall structure of the present invention;

[0015] Figure 2 Top view of the present invention;

[0016] Figure 3 Operating mode (TE 110 mode) electric field distribution diagram in the first dielectric cavity of the present invention;

[0017] Figure 4 Operating mode (deflected TE 210 mode) electric field distribution diagram of the second dielectric cavity of the present invention;

[0018] Figure 5 Amplitude-frequency response diagram of the dual-band filter coupler based on a dielectric resonator of the present invention;

[0019] Figure 6 Schematic diagram of the traditional cascaded design of the dual-band filter coupler;

[0020] Figure 7 Schematic diagram of the integrated design of the dual-band differential filter coupler proposed by the present invention.

[0021] Explanation of reference numerals:

[0022] 1. First dielectric cavity; 2. Second dielectric cavity; 3. Octagonal dielectric resonator; 4. Input end; 5. Through end; 6. Coupling end; 7. Isolation end; 8. Feeding probe. Detailed Embodiments

[0023] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail in conjunction with the drawings.

[0024] Embodiment 1:

[0025] This embodiment provides a dual-band filtering coupler based on a dielectric resonator. The specific structural schematic diagram is as shown in Figures 1 to 2 which includes a first dielectric cavity 1. On both sides of the first dielectric cavity 1, two groups of second dielectric cavities 2 are provided. The dielectric constants of each of the second dielectric cavities 2 are the same and greater than the dielectric constant of the first dielectric cavity 1. The first dielectric cavity 1 includes four groups of octagonal dielectric resonators 3. The four groups of octagonal dielectric resonators 3 are arranged in a 2×2 array. The octagonal dielectric resonators 3 are coupled to each other through rectangular dielectric sheets, and the widths of the dielectric sheets in the x-axis and y-axis directions are different. Each of the octagonal dielectric resonators 3 is obtained by cutting off four corners of a square dielectric resonator, and each corner is cut off an isosceles triangle. Each of the octagonal dielectric resonators 3 has the same size. Each of the second dielectric cavities 2 is obtained by cutting off a pair of opposite corners of a rectangular dielectric resonator. The sizes between the opposite corners are different, and they are both isosceles triangles. The first dielectric cavity 1 and the second dielectric cavities 2 are coupled through rectangular dielectric sheets. At the middle part of each of the octagonal dielectric resonators 3, a pair of differential ports are arranged up and down. The differential ports on the four groups of octagonal dielectric resonators 3 are respectively the input end 4, the through end 5, the coupling end 6, and the isolation end 7, which are respectively used as differential port 1 (including port 1 at the upper end of the octagonal dielectric resonator 3 + and port 1 at the lower end - ), differential port 2 (including port 2 at the upper end of the octagonal dielectric resonator 3 + and port 2 at the lower end - ), differential port 3 (including port 3 at the upper end of the octagonal dielectric resonator 3 + and port 3 at the lower end - ), and differential port 4 (including port 4 at the upper end of the octagonal dielectric resonator 3 + and port 4 at the lower end - ). The input end 4 and the isolation end 7 are on the same side, and the sides of the octagonal dielectric resonators 3 excited by them are both coupled to the adjacent second dielectric cavities 2. The through end 5 and the coupling end 6 are on the same side, and the sides of the octagonal dielectric resonators 3 excited by them are both coupled to the adjacent second dielectric cavities 2. A feeding probe 8 is arranged in the differential port. The schematic diagram of the traditional cascaded design of the dual-band filtering coupler is as shown in Figure 6 and the schematic diagram of the integrated design of the dual-band differential filtering coupler proposed by the present invention is as shown in Figure 7As shown; after comparison, it can be found that in modern communication systems, cavity filters and cavity couplers often work in cascade, and an additional matching network needs to be configured between them. Therefore, the hardware cost is high and the system space occupied is large; while in this application, through resonator multiplexing technology, the coupler and the dual-band filter are integrated and designed in one device, which can significantly reduce the circuit volume and eliminate the cascade loss between them.

[0026] In this embodiment, in the specific circuit design process, the dielectric constant of the first dielectric cavity 1 is 9.8, and the dielectric constant of the second dielectric cavity 2 is 45. The first dielectric cavity 1 and the surrounding second dielectric cavities 2 are adhesively bonded with glue, and the connecting contact surfaces are not silver-plated, and the remaining surfaces are all silver-plated.

[0027] The single cavity (surface silver-plated) mode used by the first dielectric cavity 1 is TE 110 (The electric field distribution in the single cavity is as Figure 3 shown), and the resonant frequency set in the embodiment is 3.47 GHz. By adjusting the size of the chamfers around the cavity, its resonant frequency can be finely tuned. Since the inclined surface of the chamfer is not large, it is convenient to polish and adjust the device during the physical debugging stage.

[0028] The second dielectric cavity 2 is obtained by chamfering a pair of diagonals (cutting off an isosceles triangle) on the basis of a rectangular dielectric cavity (the lengths of the two sides of the rectangle are not limited and can be a square). As Figure 4 shown, after chamfering the rectangular dielectric cavity, the image of the electric field standing wave distribution in the TE 210 mode inside the cavity will deflect towards the other diagonal direction. In this embodiment, the TE 210 mode with clockwise deflection is adopted, and the initially set resonant frequency is 3.25 GHz.

[0029] The size of the chamfer will affect the resonant frequency of the electric field mode. The larger the chamfer, the higher the resonant frequency of the electric field mode. The large chamfer in the upper left corner of the dielectric cavity is used for the initial determination of the resonant frequency, and the small chamfer in the lower right corner is used for polishing and fine-tuning during product testing.

[0030] Embodiment 2:

[0031] This embodiment provides a dual-band filtering coupler optimized based on the device provided in the above-mentioned Embodiment 1. After optimization and debugging, the design parameters of the dual-band filtering coupler are determined. The dimensional parameters of this embodiment are shown in Table 1. In addition, all the chamfered edges (the length of the waist of the cut isosceles triangle) in the first dielectric cavity 1 are 4 mm, the chamfered edges of the large chamfers in the second dielectric cavity 2 are all 7 mm, the chamfered edges of the small chamfers are all 1 mm, and the height of all dielectric cavities is 8 mm. The diameter of all the feeding probes 8 inserted into the first dielectric cavity 1 is 1.4 mm, and the insertion depth is 2.1 mm. It should be particularly noted that the embodiment given in the present invention only shows a dimensional scheme. On this basis, by appropriately reducing the size of the resonator, the two passbands can be set in the N78 in-building distribution signal coverage frequency band (3300 - 3800 MHz), so as to obtain a dual-band filtering coupler that can be used in the in-building distribution system.

[0032] Table 1: Dimensional parameter table of this embodiment

[0033] Parameter <![CDATA[l1]]> <![CDATA[l2]]> <![CDATA[l3]]> <![CDATA[d1]]> <![CDATA[d2]]> Value (mm) 20 15 16 7.8 2 Parameter <![CDATA[d3]]> <![CDATA[d4]]> <![CDATA[d5]]> <![CDATA[d6]]> Value (mm) 4 2 6 1

[0034] The amplitude-frequency response of the dual-band filtering coupler based on the dielectric resonator is as Figure 5 shown. The center frequencies of the low passband and the high passband are 3.15 GHz and 3.23 GHz respectively, and there is a transmission zero between the passbands. From the through-end, the insertion loss of the two passbands is better than 0.9 dB. From the input end, the return loss of the dual-band is better than 16 dB. In addition, the coupling degree of the dual-band is 20 dB, and the common-mode rejection performance is better than -96 dB in a relatively wide frequency band.

[0035] The present invention integrates the design of a dual-band filter and a coupler, reuses the dielectric resonator, and realizes differential signal transmission. On the basis of ensuring communication quality and reducing the circuit size, the production cost is effectively reduced. The simulation results show that the dual-band differential filtering coupler has low insertion loss, good isolation between passbands, and excellent common-mode rejection performance, and has significant advantages in dual-frequency wireless communication systems.

[0036] The above is only the preferred embodiment of the present invention, and does not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A dual-band filtering coupler based on a dielectric resonator, characterized in that, Comprising a first dielectric cavity (1), two sets of second dielectric cavities (2) are provided on both sides of the first dielectric cavity (1); the dielectric constants of each of the second dielectric cavities (2) are the same and greater than the dielectric constant of the first dielectric cavity (1).

2. The dual-band filtering coupler based on a dielectric resonator according to claim 1, wherein The first dielectric cavity (1) includes four sets of octagonal dielectric resonators (3); the four sets of octagonal dielectric resonators (3) are arranged in a 2×2 array, and the two octagonal dielectric resonators (3) are coupled through a rectangular dielectric sheet, and the widths of the dielectric sheets along the x-axis and y-axis directions are different.

3. The dual-band filter coupler based on a dielectric resonator according to claim 2, wherein Each of the octagonal dielectric resonators (3) is obtained by cutting off four corners of a square dielectric resonator, and each corner is cut off an isosceles triangle.

4. The dual-band filtering coupler based on a dielectric resonator according to claim 3, wherein, Each of the octagonal dielectric resonators (3) is of the same size.

5. The dual-band filtering coupler based on a dielectric resonator according to claim 4, wherein Each of the second dielectric cavities (2) is obtained by cutting off a pair of opposite corners of a rectangular dielectric resonator, and the sizes between the opposite corners are different and are both isosceles triangles.

6. The dual-band filter coupler based on a dielectric resonator according to claim 5, wherein The first dielectric cavity (1) and the second dielectric cavity (2) are coupled through a rectangular dielectric sheet.

7. The dual-band filtering coupler based on a dielectric resonator according to claim 6, characterized in that, A pair of differential ports are provided above and below the middle of each of the octagonal dielectric resonators (3).

8. The dual-band filtering coupler based on a dielectric resonator according to claim 7, wherein, The differential ports on the four sets of octagonal dielectric resonators (3) are respectively an input end (4), a through end (5), a coupling end (6) and an isolation end (7).

9. The dual-band filter coupler based on a dielectric resonator according to claim 8, wherein The input end (4) and the isolation end (7) are on the same side, and the sides of the octagonal dielectric resonators (3) excited by them are both coupled to the adjacent second dielectric cavity (2); the through end (5) and the coupling end (6) are on the same side, and the sides of the octagonal dielectric resonators (3) excited by them are both coupled to the adjacent second dielectric cavity (2).

10. The dual-band filtering coupler based on a dielectric resonator according to claim 9, wherein A feeding probe (8) is provided in the differential port.

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