Miniaturized four-mode dielectric waveguide resonator and filter containing the same

Abstract

The present invention relates to a miniaturized four-mode dielectric waveguide resonator and a filter including the resonator, and belongs to the technical field of communication equipment components. The present invention arranges five metallized blind holes on the top of a rectangular dielectric waveguide resonator to form a four-mode dielectric waveguide resonator. The design of a filter using the four-mode dielectric waveguide resonator can greatly reduce the number of resonators, thereby reducing the volume. Compared with a filter using a single-mode resonator, the volume can be reduced by about 75%. In addition, the resonant frequency and external quality factor of each mode of the four-mode dielectric waveguide resonator are independently controllable, and no additional structure needs to be added, which brings a lot of flexibility to the design of the filter. The resonant frequency of the mode can be adjusted by adjusting the depth of different metallized blind holes, and the external quality factor can be adjusted by adjusting the position of different blind holes.

Description

Technical Field

[0001] The present invention relates to the technical field of communication equipment components, and in particular to a miniaturized four-mode dielectric waveguide resonator and a filter comprising the resonator. Background Art

[0002] The modern information and communication industry is developing rapidly, and mobile communication systems are constantly being updated. Since 2019, China has officially approved the commercial use of 5G, which has opened up a wider market in the field of wireless communication. In 2020, 5G-A was officially commercialized, which put forward more stringent requirements on the performance of the RF front-end system. RF front-end devices are the basis of wireless communication, and filters are an important part of RF front-end devices. Therefore, the performance of filters also affects the entire communication system. How to develop and design high-performance RF filters has become a widely concerned issue in academia and industry. For 5G and future mobile communication systems, the overall usage of base station filters has greatly increased, which puts forward more stringent requirements on the size, weight, loss, selectivity, etc. of base station filters. Dielectric waveguide filters are realized by metallizing the surface of an integrated high dielectric constant and low-loss dielectric ceramic structure, which can well meet the requirements of low loss, miniaturization, and lightweight of 5G and future mobile communication systems. In order to further achieve miniaturization, in dielectric waveguide filters, the use of multimode technology can reduce the number of resonators while ensuring filtering performance, thereby reducing the size of dielectric waveguide filters, which is of great significance to the development of filter miniaturization.

[0003] Most existing multimode dielectric waveguide filters use dual-mode or triple-mode resonator designs, which have the following two main disadvantages:

[0004] First, the existing multimode dielectric waveguide filters are still relatively large in size. Most of the existing multimode dielectric waveguide filters are designed with dual-mode or triple-mode resonators. In order to achieve good filtering performance, multiple resonators are usually required, so the larger size is difficult to avoid.

[0005] Second, in a multimode dielectric waveguide filter, the resonant frequency and external quality factor of each resonant mode are difficult to control independently. The structure of a multimode resonator is more complex than that of a single-mode resonator, and adjusting the resonant frequency or external quality factor of a single mode often affects other modes. To achieve independent control of the resonant frequency and external quality factor of each mode, additional structures are usually required, which reduces the unloaded quality factor of the resonator and increases processing costs. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies in the above-mentioned prior art. The present invention proposes a miniaturized four-mode dielectric waveguide resonator and a filter including the resonator. The dielectric waveguide filter has the advantages of miniaturization, controllable resonant frequency and external quality factor, so that the filter has better design flexibility.

[0007] In order to achieve the purpose of the present invention, the present invention provides a miniaturized four-mode dielectric waveguide resonator, including a dielectric waveguide resonator with a metallized surface, wherein the upper surface of the dielectric waveguide resonator is provided with first to fourth metallized blind holes, wherein the first to fourth metallized blind holes are respectively located in the first to fourth quadrants of the upper surface of the dielectric waveguide resonator, and are used to adjust the resonant frequencies of the first to fourth modes of the resonator in a one-to-one correspondence, and the upper surface of the dielectric waveguide resonator also has a fifth metallized blind hole, wherein the fifth metallized blind hole is located at the junction of the four quadrants of the upper surface of the dielectric waveguide resonator, and is used to adjust the difference in the resonant frequencies of the four resonant modes to reduce the coupling between the four resonant modes, thereby making the four resonant modes independently controllable.

[0008] In addition, the present invention also claims protection for a miniaturized dielectric waveguide filter based on a four-mode resonator, comprising a printed circuit board and a dielectric block arranged above the printed circuit board, the upper and lower surfaces of the printed circuit board are covered with metal layers, the metal layer on the lower surface of the dielectric block is electrically connected to the metal layer on the upper surface of the printed circuit board, and the upper surface of the printed circuit board is provided with an input port for connecting a source and an output port for connecting a load, characterized in that: the dielectric block includes the above-mentioned miniaturized four-mode dielectric waveguide resonator, and the two opposite side surfaces of the dielectric block are respectively provided with a first coupling blind hole for signal feeding in and a second coupling blind hole for signal feeding out, the input port is conductively connected to the first coupling blind hole, so that the source is coupled to the miniaturized four-mode dielectric waveguide resonator; the output port is conductively connected to the second coupling blind hole, so that the load is coupled to the miniaturized four-mode dielectric waveguide resonator.

[0009] Furthermore, an input microstrip line and an output microstrip line insulated from the metal layer are provided on the upper surface of the printed circuit board; the outer end of the input microstrip line is connected to the input port, and the inner end is connected to the first coupling blind hole via a first transmission microstrip line provided in the dielectric block; the outer end of the output microstrip line is connected to the output port, and the inner end is connected to the second coupling blind hole via a second transmission microstrip line provided in the dielectric block.

[0010] Furthermore, an annular non-metallic portion is etched around the first transmission microstrip line and the second transmission microstrip line, so that the first transmission microstrip line and the second transmission microstrip line are insulated from the metal layer on the surface of the dielectric waveguide resonator.

[0011] The signal is fed into the miniaturized four-mode dielectric waveguide resonator from the input port via the input microstrip line, the first transmission microstrip line, and the first coupling blind hole, and the four resonance modes of the miniaturized four-mode dielectric waveguide resonator are excited at the same time. Then, the four resonance modes pass through the second coupling blind hole and are output from the output port via the second transmission microstrip line and the output microstrip line.

[0012] The present invention arranges five metalized blind holes on the top of the rectangular dielectric waveguide resonator to form a four-mode dielectric waveguide resonator. The design of the filter using the four-mode dielectric waveguide resonator can greatly reduce the number of resonators, thereby reducing the volume. Compared with the filter using a single-mode resonator, the volume can be reduced by about 75%.

[0013] In addition, the resonant frequency and external quality factor of each mode of the four-mode dielectric waveguide resonator are independently controllable without adding additional structures, which brings a lot of flexibility to the design of the filter. The resonant frequency of the mode can be adjusted by adjusting the depth of different metallized blind holes, and the external quality factor can be adjusted by adjusting the position of different blind holes.

[0014] The miniaturized dielectric waveguide filter based on the quad-mode resonator proposed in the present invention has the advantages of miniaturization and independent controllability of the resonant frequency and the external quality factor, and the passband range can cover 3450MHz to 3550MHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the miniaturized four-mode dielectric waveguide resonator used in the filter of the present invention.

[0017] Figure 2 It is a three-dimensional exploded diagram of the four-mode dielectric waveguide filter of the present invention.

[0018] Figure 3 These are the S parameter simulation and test results of the four-mode dielectric waveguide filter of the present invention.

[0019] Figure 4 It is a coupling topology diagram of the four-mode dielectric waveguide filter of the present invention.

[0020] Figure 5 It is a coupling matrix diagram of the four-mode dielectric waveguide filter of the present invention.

[0021] Figure 6 This is the simulation result of the effect of the depth of the fifth blind hole on the resonant frequencies of the four modes.

[0022] Figure 7These are the simulation results of the effects of the depths of the first to fourth blind holes on the resonance frequencies of the four modes (a) the first blind hole 31, (b) the second blind hole 32, (c) the third blind hole 33, and (d) the fourth blind hole 34.

[0023] Figure 8 It is a partial dimension mark of the four-mode dielectric waveguide filter of the present invention.

[0024] Fig. 9 These are the simulation results of the effect of the first and fourth blind hole positions on the external quality factors of the four modes (a) X1, (b) X2, (c) X3, and (d) X4. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] Embodiment 1

[0027] The present invention uses a square dielectric waveguide resonator with five metalized blind holes on the top for analysis and design. The three-dimensional structure diagram of the four-mode dielectric waveguide resonator proposed in the scheme is shown in the figure. Figure 1 As shown, a square dielectric waveguide resonator A (a dielectric waveguide resonator can be in various shapes, such as square, rectangular, circular, elliptical, etc.) with a silver-plated (metallized) surface is provided on the upper surface of the dielectric waveguide resonator A with a first metallized blind hole 31, a second metallized blind hole 32, a third metallized blind hole 33 and a fourth metallized blind hole 34. The four-mode dielectric waveguide resonator has four resonant modes, which are equivalent to the quasi-TM modes of the resonator distributed in the four corners. The first metallized blind hole 31, the second metallized blind hole 32, the third metallized blind hole 33 and the fourth metallized blind hole 34 are respectively located in the first to fourth quadrants of the upper surface of the dielectric waveguide resonator A, and are used to adjust the resonant frequencies of the first to fourth modes (each) of the resonator one by one. The upper surface of the dielectric waveguide resonator A also has a fifth metallized blind hole 35, which is located at the junction of the four quadrants of the upper surface of the dielectric waveguide resonator A, and is used to adjust the difference in the resonant frequencies of the four resonant modes to reduce the coupling between the four resonant modes, so that the four resonant modes are independently controllable. The first to fourth mode resonant frequencies are adjusted by the depths of the first to fourth metallized blind holes (31, 32, 33, 34), respectively.

[0028] The present invention arranges five metalized blind holes on the top of the rectangular dielectric waveguide resonator to form a four-mode dielectric waveguide resonator. The design of the filter using the four-mode dielectric waveguide resonator can greatly reduce the number of resonators, thereby reducing the volume. Compared with the filter using a single-mode resonator, the volume can be reduced by about 75%.

[0029] Embodiment 2

[0030] like Figure 2 As shown, the miniaturized dielectric waveguide filter based on the four-mode resonator in this embodiment includes a printed circuit board 2 and a dielectric block 1 above the printed circuit board 2. The upper and lower surfaces of the printed circuit board 2 are covered with metal layers, and the metal layer on the lower surface of the dielectric block 1 is electrically connected to the metal layer on the upper surface of the printed circuit board. The upper surface of the printed circuit board 2 is provided with an input port P1 for connecting the source S and an output port P2 for connecting the load L. The dielectric block 1 includes the miniaturized four-mode dielectric waveguide resonator as claimed in claim 1, and the two opposite sides of the dielectric block 1 are respectively provided with a first coupling blind hole 36 for signal feeding in and a second coupling blind hole 37 for signal feeding out, the input port P1 is conductively connected to the first coupling blind hole 36, so that the source S is coupled to the miniaturized four-mode dielectric waveguide resonator; the output port P2 is conductively connected to the second coupling blind hole 37, so that the load L is coupled to the miniaturized four-mode dielectric waveguide resonator. In this example, the first coupling blind hole 36 and the second coupling blind hole 37 are perpendicular to the side of the dielectric block 1 and are located on the central axis of the dielectric block 1.

[0031] like Figure 2 As shown, in this embodiment, an input microstrip line 51 and an output microstrip line 52 insulated from the metal layer are provided on the upper surface of the printed circuit board 2. The outer end of the input microstrip line 51 is connected to the input port P1, and the inner end is connected to the first coupling blind hole 36 via the first transmission microstrip line 41 provided in the dielectric block 1; the outer end of the output microstrip line 52 is connected to the output port P2, and the inner end is connected to the second coupling blind hole 37 via the second transmission microstrip line 42 provided in the dielectric block. An annular non-metallic part is etched around the first transmission microstrip line 41 and the second transmission microstrip line 42, so that the first transmission microstrip line 41 and the second transmission microstrip line 42 are insulated from the metal layer on the surface of the dielectric waveguide resonator. In the present invention, the input microstrip line 51 and the output microstrip line 52 are insulated from the metal layer on the upper surface of the printed circuit board 2 by etching the periphery of the input microstrip line 51 and the output microstrip line 52.

[0032] The working process of the fourth-order filter is described below: the signal is fed from the input port P1 into the miniaturized four-mode dielectric waveguide resonator via the input microstrip line 51, the first transmission microstrip line 41, and the first coupling blind hole 36, and the four resonant modes of the miniaturized four-mode dielectric waveguide resonator are excited at the same time. Then, these four resonant modes pass through the second coupling blind hole 37 and are output from the output port P2 via the second transmission microstrip line 42 and the output microstrip line 52.

[0033] The present invention uses a four-mode dielectric waveguide resonator to realize a bandpass filter. Compared with the traditional single-mode solution, the number of resonators is greatly reduced, so the designed filter can be reduced by about 75% compared with the traditional single-mode solution, and miniaturization is better achieved. In addition, the resonant frequency and external quality factor of each mode can be independently controlled, which brings flexibility to the design of the filter.

[0034] The present invention is a dielectric waveguide filter based on a four-mode resonator, and its simulation and test results are as follows: Figure 3 As shown in the figure. From the simulation results, it can be seen that the passband range of the filter is 3.45GHz to 3.55GHz, the return loss in the band is greater than 18dB, the minimum insertion loss is 0.68dB, and three transmission zeros are generated outside the passband at 3.428GHz, 3.57GHz and 3.59GHz. The measured return loss is greater than 13dB, and the minimum insertion loss is 0.95dB.

[0035] The coupling topology of the filter is shown in the figure Figure 4 The source and the load simultaneously excite four resonant modes, forming a parallel coupling topology. The coupling coefficient (M) between the source S and the four resonant modes of the miniaturized four-mode dielectric waveguide resonator S1 、M S2 、M S3 、M S4 ) are adjusted by the distances between the first to fourth metalized blind holes (31, 32, 33, 34) and the midlines of the X-axis and the Y-axis respectively; the coupling coefficients (M) between the load (L) and the four resonant modes of the miniaturized four-mode dielectric waveguide resonator 1L 、M 2L 、M 3L 、M 4L ) are adjusted by the distances between the first to fourth metalized blind holes (31, 32, 33, 34) and the midlines of the X-axis and the Y-axis. The relationship between the coupling coefficient and the external quality factor is as follows:

[0036]

[0037] Among them, f r is the passband center frequency, BW is the passband bandwidth, i=1,2,3,4, M si is the coupling coefficient.

[0038] Figure 5 The coupling matrix of the filter is shown. Since the electric field distribution of modes 1 and 3 is in opposite directions at the source and load ports, and the electric field distribution of modes 2 and 4 is in the same direction at the source and load ports, the input and output coupling signs of modes 1 and 3 are opposite (M S1 =-M 1L ,M S3 =-M 3L ), the input and output coupling signs of Mode 2 and Mode 4 are the same (M S2 =M 2L ,M S4 =M 4L ), which results in 3 transmission zeros.

[0039] Figure 6 The effect of the depth of the fifth metallized blind hole 35 on the resonant frequencies of the four modes is shown. When there is no blind hole 35, the frequency difference between mode 1 and mode 4 is 0.4 GHz. After the blind hole 35 is added, as the depth of the blind hole increases, the difference between the resonant frequencies of mode 1 and mode 4 becomes smaller and smaller. The addition of the blind hole 35 makes the resonant frequencies of the four modes closer, thus forming the passband of the filter.

[0040] Figure 7 The effect of the depth of the metallized blind holes 31, 32, 33, and 34 on the resonant frequencies of different modes is shown. When the depth of the metallized blind hole 31 is increased, the resonant frequency of mode 1 decreases, while the resonant frequencies of the other three modes remain almost unchanged. Similarly, increasing the depth of the second to fourth metallized blind holes (32, 33, and 34) respectively decreases the resonant frequencies of modes 2, 3, and 4, while the resonant frequencies of the other modes remain almost unchanged. The resonant frequencies of the four modes are independently controllable.

[0041] Figure 8 A top view of the four-mode dielectric waveguide resonator is shown, wherein X1, X2, X3, and X4 are respectively the distances between the midpoints of the first to fourth metallized blind holes (31, 32, 33, and 34) and the center line of the resonator in the x-axis direction, and Y1, Y2, Y3, and Y4 are respectively the distances between the midpoints of the first to fourth metallized blind holes (31, 32, 33, and 34) and the center line of the resonator in the y-axis direction.

[0042] Fig. 9 The influence of the position of the first to fourth metalized blind holes (31, 32, 33, 34) on the external quality factors of different modes is shown. Increasing the distance X1 between the metalized blind hole 31 and the center line of the dielectric waveguide resonator in the x-axis direction will reduce the external quality factor of mode 1, while the external quality factors of the other three modes will not change much. Similarly, increasing X2, X3, and X4 will reduce the external quality factors of mode 2, mode 3, and mode 4, respectively, while the external quality factors of other modes remain almost unchanged. Increasing the distances Y1 and Y3 between the metalized blind hole 31 and the center line of the dielectric waveguide resonator in the y-axis direction of the dielectric waveguide resonator in a certain range will increase the external quality factors of mode 1 and mode 3, and increasing the distances Y2 and Y4 between the metalized blind hole 32 and the center line of the dielectric waveguide resonator in the y-axis direction will reduce the external quality factors of mode 2 and mode 4. The external quality factor of each mode can basically be controlled separately.

[0043] The dielectric waveguide filter designed in the present invention has a passband covering 3450 MHz to 3550 MHz and has high practicality.

[0044] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A miniaturized four-mode dielectric waveguide resonator, comprising a dielectric waveguide resonator (A) with a metallized surface, wherein the upper surface of the dielectric waveguide resonator (A) is provided with first to fourth metallized blind holes (31, 32, 33, 34), wherein the first to fourth metallized blind holes are respectively located in the first to fourth quadrants of the upper surface of the dielectric waveguide resonator (A), and are used to adjust the resonant frequencies of the first to fourth modes of the resonator in a one-to-one correspondence, wherein the first to fourth modes are distributed at the four corners of the resonator, and the upper surface of the dielectric waveguide resonator (A) further comprises a fifth metallized blind hole (35), wherein the fifth metallized blind hole (35) is located at the intersection of the four quadrants of the upper surface of the dielectric waveguide resonator (A), and is used to adjust the difference in resonant frequencies of the four resonant modes to reduce the coupling between the four resonant modes, thereby making the four resonant modes independently controllable; and the resonant frequencies of the first to fourth modes are respectively adjusted by the depths of the first to fourth metallized blind holes.

2. The miniaturized four-mode dielectric waveguide resonator according to claim 1, characterized in that: The dielectric waveguide resonator (A) is a rectangular dielectric resonator.

3. A miniaturized dielectric waveguide filter based on a quad-mode resonator, comprising a printed circuit board (2) and a dielectric block (1) arranged above the printed circuit board (2), wherein the upper and lower surfaces of the printed circuit board (2) are both covered with metal layers, the metal layer on the lower surface of the dielectric block (1) is electrically connected to the metal layer on the upper surface of the printed circuit board (2), and the upper surface of the printed circuit board (2) is provided with an input port (P1) for connecting to a source (S) and an output port (P2) for connecting to a load (L), characterized in that: The dielectric block (1) comprises the miniaturized four-mode dielectric waveguide resonator as claimed in claim 1, and a first coupling blind hole (36) for signal feeding in and a second coupling blind hole (37) for signal feeding out are respectively arranged on two opposite sides of the dielectric block (1), the input port (P1) is conductively connected to the first coupling blind hole (36), so that the source (S) is coupled to the miniaturized four-mode dielectric waveguide resonator; the output port (P2) is conductively connected to the second coupling blind hole (37), so that the load (L) is coupled to the miniaturized four-mode dielectric waveguide resonator.

4. The miniaturized dielectric waveguide filter based on the quad-mode resonator according to claim 3, characterized in that: The first coupling blind hole (36) and the second coupling blind hole (37) are perpendicular to the side of the dielectric block (1) and are located on the central axis of the dielectric block (1).

5. The miniaturized dielectric waveguide filter based on quad-mode resonator according to claim 4, characterized in that: The coupling coefficients (M) between the source (S) and the four resonant modes of the miniaturized four-mode dielectric waveguide resonator S1 、M S2 、M S3 、M S4 ) are adjusted by adjusting the distances between the first to fourth metallized blind holes (31, 32, 33, 34) and the midlines of the X-axis and the Y-axis respectively; The coupling coefficients (M) between the load (L) and the four resonant modes of the miniaturized four-mode dielectric waveguide resonator 1L 、M 2L 、M 3L 、M 4L ) are adjusted by the distances between the first to fourth metallized blind holes (31, 32, 33, 34) and the center lines of the X-axis and the Y-axis, respectively.

6. The miniaturized dielectric waveguide filter based on quad-mode resonator according to claim 5, characterized in that: An input microstrip line (51) and an output microstrip line (52) insulated from the metal layer are arranged on the upper surface of the printed circuit board (2); the outer end of the input microstrip line (51) is connected to the input port (P1), and the inner end is connected to the first coupling blind hole (36) via a first transmission microstrip line (41) arranged on the dielectric block (1); The outer end of the output microstrip line (52) is connected to the output port (P2), and the inner end is connected to the second coupling blind hole (37) via a second transmission microstrip line (42) arranged in the dielectric block.

7. The miniaturized dielectric waveguide filter based on quad-mode resonator according to claim 6, characterized in that: An annular non-metallic portion is etched around the first transmission microstrip line (41) and the second transmission microstrip line (42), so that the first transmission microstrip line (41) and the second transmission microstrip line (42) are insulated from the metal layer on the surface of the dielectric waveguide resonator.

8. The miniaturized dielectric waveguide filter based on quad-mode resonator according to claim 7, characterized in that: By etching the peripheries of the input microstrip line (51) and the output microstrip line (52), the input microstrip line (51) and the output microstrip line (52) are insulated from the metal layer on the upper surface of the printed circuit board (2).

9. The miniaturized dielectric waveguide filter based on quad-mode resonator according to claim 8, characterized in that: A signal is fed from an input port (P1) through an input microstrip line (51), a first transmission microstrip line (41), and a first coupling blind hole (36) into the miniaturized four-mode dielectric waveguide resonator, and four resonance modes of the miniaturized four-mode dielectric waveguide resonator are excited at the same time. The four resonance modes are then output from an output port (P2) through a second coupling blind hole (37) and a second transmission microstrip line (42) and an output microstrip line (52).

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