Dielectric waveguide-based tri-band duplexer design method and duplexer

Abstract

The invention provides a three-band duplexer design method based on a dielectric waveguide and a duplexer, and relates to the technical field of wireless communication. According to the method, a polynomial of the tri-band duplexer is calculated through an iterative program, and then a coupling matrix is obtained. The coupling strength among the resonant cavities can be accurately obtained through the coupling matrix, so that a proper physical structure is selected to realize the required three-band response; and the three-band duplexer is manufactured by adopting a dielectric waveguide technology. The resonant frequency of the resonant cavity can be controlled by adjusting the insertion depth of the metal column in the resonant cavity; the feed intensity can be adjusted by adjusting the insertion depth of the SMA connector; the coupling strength can be adjusted by changing the length of the inductive coupling window between the resonant cavities and the size of the inductive coupling column. When all coupling values match the coupling matrix, the duplexer will achieve an expected frequency band response.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a three-band duplexer design method and duplexer based on dielectric waveguides. Background Technology

[0002] Modern microwave and millimeter-wave communication systems increasingly demand microwave devices with low loss, high power capacity, high integration, and small size. Dielectric waveguides are waveguide structures that use dielectric materials as the primary transmission medium. Compared to traditional metallic waveguides (such as rectangular waveguides), dielectric waveguides offer significant advantages in terms of small size, light weight, and low manufacturing cost. A duplexer is a microwave device capable of simultaneously transmitting signals of different frequency bands on the same transmission line. It is widely used in wireless communication systems, especially in environments with limited spectrum resources. Duplexers utilize frequency division multiplexing (FDM) technology to separate or combine signals from different frequency bands, thereby achieving bidirectional communication. Most existing duplexer designs are based on dielectric resonators or metallic waveguides, which often suffer from large size, high loss, or high cost. To meet the requirements of high efficiency and miniaturization, novel duplexer designs based on dielectric waveguides have emerged, offering lower loss, smaller size, and higher integration, becoming an indispensable component in modern communication systems.

[0003] Multi-band communication systems have become a significant trend in wireless communication technology development in recent years, especially in 5G and higher frequency bands (such as millimeter-wave communication), where efficient utilization of spectrum resources is crucial. By employing multi-band technology, multiple frequency bands can be supported for signal transmission within a single device, thereby improving spectrum utilization efficiency and reducing overall system costs. Tri-band systems are particularly suitable for complex communication environments, such as communication devices that simultaneously support multiple communication standards or frequency bands. Most existing duplexers are designed for dual-band integration; tri-band integration is still relatively rare. Furthermore, achieving isolation between different frequency bands in multi-band duplexers remains a technical challenge.

[0004] Therefore, how to design a highly integrated tri-band duplexer while maintaining miniaturization and high efficiency has become a pressing technical challenge. Summary of the Invention

[0005] Therefore, this invention provides a three-band duplexer design method and duplexer based on dielectric waveguides to address the problems in modern microwave and millimeter-wave communication systems. While various duplexer schemes based on metallic waveguides, dielectric resonators, and microstrip lines have been proposed, existing technologies generally suffer from large device size, complex structure, high manufacturing cost, and difficulty in simultaneously achieving adequate insertion loss and inter-band isolation. Furthermore, traditional duplexers are mostly designed for dual-band applications, making it difficult to meet the needs of multi-band communication systems. This invention, for the first time, utilizes the inherent low insertion loss and high...Q This invention utilizes the advantages of high efficiency and significant power handling capabilities to design a tri-band duplexer. Furthermore, it proposes a novel integrated method for tri-band duplexers, enabling efficient transmission across multiple frequency bands. This meets the requirements of multi-band communication systems for miniaturization, high integration, and low loss, and has broad application prospects.

[0006] This invention provides a three-band duplexer design method based on dielectric waveguides, comprising the following steps: S1. Synthesize the initial polynomials for the TX and RX channels according to the design specifications, and map the polynomials to the normalized frequency domain of the duplexer. S2. Solve for the iterative initial polynomial P of the three-band duplexer. t (s) and P r (s), where P t (s) = P TXn (s) ·S RX (s) and P r (s) = P TXn (s) · S TX (s), the roots of the duplexer polynomial D(s) are F TXn (s), F RXn The product of the roots of (s) and the zeros introduced by the common resonant junction determines the value; S3. Based on the definition of return loss, solve for the normalization coefficients of the three-band duplexer at the passband boundaries of TX and RX respectively. p 0t and p 0r Then, the duplexer polynomial D(s) is solved according to the law of conservation of energy, and one iteration is completed at this time; S4, Update S TX and S RX Before and after the update S TX and S RX Compare the roots respectively, if S TX and S RX If all roots converge to the specified level, the iteration ends; otherwise, repeat steps S2 and S3 until the roots converge to the specified level. S5. After iteration, solve for the coupling matrix of the duplexer.

[0007] Furthermore, duplexers S The parameters are given by the polynomials N(s) and P. t (s), P r (s), D(s), and three normalization coefficients n0、 p 0t and p 0 Confirmed: .

[0008] Furthermore, in step S1, the polynomials of the TX and RX filters are determined by the following equation: .

[0009] Furthermore, in step S4, the update is performed using the following formula. S TX and S RX : ; in c 0 represents the capacitance value. The design methodology includes: proposing an iterative algorithm for generating the synthesized polynomial and coupling matrix of the target response of a three-band duplexer; and using the solved coupling matrix to guide and implement the physical structure and parameter design of the three-band dielectric waveguide duplexer. This algorithm is based on the relationship between the three-band polynomial and its two channel polynomials. By synthesizing the polynomials of the two channels separately, an initial solution for the three-band polynomial is obtained. Then, an iterative algorithm updates the duplexer's polynomial multiple times to obtain the polynomial and coupling matrix of the three-band duplexer.

[0010] The present invention also provides a duplexer designed by the above method, comprising a common cavity, with TX and RX channels respectively connected to both sides of the common cavity. The TX channel includes a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth resonant cavity, a fifth resonant cavity, and a sixth resonant cavity; the first, second, and third resonant cavities are sequentially connected to one side of the common cavity; the fifth and fourth resonant cavities are respectively connected to the second and third resonant cavities; the sixth resonant cavity is connected to the fifth resonant cavity. The RX channel includes a seventh resonant cavity, an eighth resonant cavity, and a ninth resonant cavity; the seventh resonant cavity is connected to the other side of the common cavity; the eighth resonant cavity is connected to the seventh resonant cavity, and the ninth resonant cavity is connected to the eighth resonant cavity.

[0011] Furthermore, ports are provided below the sixth resonant cavity, the ninth resonant cavity, and the common cavity. The second, third, fourth, and fifth resonant cavities are arranged in a grid pattern, and adjacent resonant cavities are interconnected. The common cavity, the seventh, eighth, and ninth resonant cavities are also arranged in a grid pattern.

[0012] The present invention has the following advantages over the prior art: 1. This invention utilizes the load effect between the channels of a duplexer to propose a new iterative procedure for solving the duplexer polynomial and coupling matrix, thereby improving the comprehensive design theory of existing multi-band duplexers. The designed three-band duplexer has center frequencies of 1.764GHz, 1.824GHz, and 1.884GHz for the three bands, with corresponding minimum insertion losses of 0.49dB, 0.63dB, and 0.40dB, respectively; the device size is 113×44×14mm, the return loss of each channel is greater than 15dB, and the isolation exceeds 30dB.

[0013] 2. This invention proposes a novel synthesis method for three-band duplexers, which can solve for the polynomial and coupling matrix of the three-band duplexer. Using the solved coupling matrix, a three-band duplexer is designed for the first time using a dielectric waveguide, exhibiting excellent performance such as low loss, high Q value, small size, and simple structure. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is a flowchart of the three-band duplexer polynomial and coupling matrix method in this invention.

[0016] Figure 2 This is the S-parameter response diagram obtained by solving the polynomial and coupling matrix method of the three-band duplexer in this invention.

[0017] Figure 3 This is a 3D structural schematic diagram of the three-band duplexer of the present invention.

[0018] Figure 4 This is a top view of the three-band duplexer of the present invention.

[0019] Figure 5 The external quality factor in the three-band duplexer of this invention Q e Extraction results image.

[0020] Figure 6 This is a simulation result diagram of the three-band duplexer of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Common cavity; 2. First resonant cavity; 3. Second resonant cavity; 4. Third resonant cavity; 5. Fourth resonant cavity; 6. Fifth resonant cavity; 7. Sixth resonant cavity; 8. Seventh resonant cavity; 9. Eighth resonant cavity; 10. Ninth resonant cavity; 11. Port. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Reference Figure 1 This invention provides a design method for a three-band duplexer based on a dielectric waveguide. The method includes: proposing an iterative solution algorithm for generating the target response of the three-band duplexer using a synthesized polynomial and a coupling matrix; and using the solved coupling matrix to guide and implement the physical structure and parameter design of the three-band dielectric waveguide duplexer. The proposed iterative solution algorithm is as follows: Figure 1 As shown, this algorithm is based on the relationship between the three-band polynomial and its two-channel polynomials. It obtains the initial solution of the three-band polynomial by synthesizing the polynomials of the two channels separately, and then... Figure 1 The iterative algorithm in the text updates the polynomial of the duplexer multiple times to solve for the polynomial and coupling matrix of the three-band duplexer. (Introduction...) Figure 1 Before implementing the iterative algorithm, it is necessary to analyze the relationship between the polynomials of the three-band duplexer and its TX and RX filters.

[0024] Lossless Tri-band Duplexer S The parameters can be derived from the polynomials N(s) and P. t (s), P r (s), D(s), and three normalization coefficients n 0、 p 0t and p 0 Confirmed: (1) The S-parameters of the TX filter in a three-band duplexer can be derived from the polynomial F. TX (s), E TX (s), P TXn (s) and normalization coefficients p 0TX This indicates that the S-parameters of the RX filter can be derived from P. RXn (s), E RX (s), E RX (s) and normalization coefficientsp 0RX The specific representation is as follows: (2) When the common three-port node of the duplexer is a resonant cavity, assuming the capacitance value in the equivalent low-pass circuit corresponding to the common resonant cavity is... c 0. The polynomials of the duplexer and the TX and RX filter polynomials have the following relationship: (3) in: (4) From (3), we can solve for: (5) Figure 1 The synthesis method described herein includes the following steps: S1. Synthesize the initial polynomials for the TX and RX channels according to the design specifications, and map the polynomials to the normalized frequency domain of the duplexer. S2. Solve for the iterative initial polynomial P of the three-band duplexer. t (s) and P r (s), where P t (s) = P TXn (s)· S RX (s) and P r (s) = P TXn (s) · S TX (s), the roots of the duplexer polynomial D(s) are F TXn (s), F RXn The product of the roots of (s) and the zeros introduced by the common resonant junction determines the value; S3. Based on the definition of return loss, solve for the normalization coefficients of the three-band duplexer at the passband boundaries of TX and RX respectively. p 0t and p 0r Then, the duplexer polynomial D(s) is solved according to the law of conservation of energy, and one iteration is completed at this time; S4, updated from (5) S TX and S RX Before and after the update S TX and S RX Compare the roots respectively, if S TX and S RXIf all roots converge to the specified level, the iteration ends; otherwise, repeat steps S2 and S3 until the roots converge to the specified level. S5. After iteration, solve for the coupling matrix of the duplexer; Assume that the three-band duplexer to be synthesized has two passbands of (-1, -0.6) and (0.6, 1) in the normalized frequency domain TX filter, and a passband of (-0.15, 0.15) in the RX filter. The return loss in the passband is greater than 17dB and the isolation is greater than 30dB. Figure 2 Showcase application Figure 1 The S-parameter response obtained by the algorithm verifies the proposed three-band duplexer synthesis method.

[0025] Example 2 This embodiment provides a duplexer designed using the above method. Given the polynomial of a three-band duplexer, the coupling matrix can be derived. By performing matrix transformations on the coupling matrix, an easily implementable topology can be obtained. The coupling matrix contains the coupling values ​​between each resonant cavity. Different coupling structures achieve different coupling magnitudes. The coupling structure of this application is selected based on the coupling matrix. Figure 3 A 3D structural schematic diagram of the three-band duplexer in this invention is provided. Figure 4 This is a top view of the three-band dielectric waveguide duplexer of the present invention. The duplexer includes a common cavity 1, with TX and RX channels connected to its two sides. The TX channel is the transmit channel, and the RX channel is the receive channel. The duplexer is a three-port 10 device with one antenna end and two load ends, equivalent to two channels. The TX channel includes a first resonant cavity 2, a second resonant cavity 3, a third resonant cavity 4, a fourth resonant cavity 5, a fifth resonant cavity 6, and a sixth resonant cavity 7. The first resonant cavity 2, the second resonant cavity 3, and the third resonant cavity 4 are sequentially connected to one side of the common cavity 1. The fifth resonant cavity 6 and the fourth resonant cavity 5 are respectively connected to the second resonant cavity 3 and the third resonant cavity 4. The sixth resonant cavity 7 is connected to the fifth resonant cavity 6. The RX channel includes a seventh resonant cavity 8, an eighth resonant cavity 9, and a ninth resonant cavity 9. The seventh resonant cavity 8 is connected to the other side of the common cavity 1. The eighth resonant cavity 9 is connected to the seventh resonant cavity 8, and the ninth resonant cavity 9 is connected to the eighth resonant cavity 9. Ports 10 are provided below the sixth resonant cavity 7, the ninth resonant cavity 9, and the common cavity 1. The second resonant cavity 3, the third resonant cavity 4, the fourth resonant cavity 5, and the fifth resonant cavity 6 are arranged in a grid pattern, and adjacent resonant cavities are interconnected. The common cavity 1, the seventh resonant cavity 8, the eighth resonant cavity 9, and the ninth resonant cavity 9 are also arranged in a grid pattern. The proposed layout is structurally stable, easy to debug, compact in size, and easy to use in wireless communication systems.

[0026] The three-band dielectric waveguide duplexer consists of ten resonant cavities, including a common cavity 1 and the first to ninth resonant cavities. The port 10 below the common cavity 1 directly feeds the common cavity 1, and the common cavity 1 feeds the TX and RX channels respectively. The ports 10 below the sixth resonant cavity 7 and the ninth resonant cavity 9 receive signals from their respective resonant cavities. The coupling value between each cavity is determined by the coupling matrix and a suitable coupling structure is selected for implementation.

[0027] External quality factor in a tri-band dielectric waveguide duplexer Q e Extraction results as follows Figure 5 As shown, the common cavity used in this invention is obtained by cutting four isosceles triangular prisms from the four corners of a cube. The feed depth of the source end (port 1) is adjusted. h c Controlling the power supply strength and the length of the triangle leg of the cut-off prism C l Controlling the resonant frequency of the common cavity. External quality factor. Q e With feed depth h c Related, when the depth of the feed h c When increased, external quality factor Q e The resonant frequency of the common cavity decreases, and to prevent the resonant frequency of the common cavity from becoming too low, isosceles triangular prisms are cut off from the four corners of the cube. This can be prevented by increasing the length of the legs of the cut triangular prisms. C l Increase the resonant frequency. Simulation results for a three-band dielectric waveguide duplexer are as follows: Figure 6 As shown, the center frequencies of the three frequency bands are 1.764GHz, 1.824GHz and 1.884GHz, respectively, with corresponding minimum insertion losses of 0.49dB, 0.63dB and 0.40dB. The device size is 113×44×14mm, and the return loss of each channel is greater than 15dB, with an isolation of more than 30dB.

[0028] To achieve the design goal of a three-band duplexer, this invention proposes a novel design method and develops a three-band duplexer based on dielectric waveguide technology. Traditional duplexers typically include two filters, RX and TX, which are usually single-passband filters. In this invention, the TX filter is designed as a dual-passband filter, while the RX filter is a single-passband filter, thus realizing the function of a three-band duplexer.

[0029] Since different frequency bands may influence each other, neglecting this influence could result in a poor duplexer response. Therefore, this invention proposes a three-band duplexer design method based on iterative optimization. This method calculates the polynomial of the three-band duplexer through an iterative program, thereby obtaining the coupling matrix. Using the coupling matrix, the coupling strength between each resonant cavity can be accurately determined, allowing for the selection of a suitable physical structure to achieve the desired three-band response.

[0030] Given the coupling matrix, this invention employs dielectric waveguide technology to fabricate a three-band duplexer. The resonant frequency of the resonant cavity can be controlled by adjusting the insertion depth of the metal pillars within it; the feed strength can be adjusted by adjusting the insertion depth of the SMA connectors; and the coupling strength can be adjusted by changing the length of the inductive coupling window between the resonant cavities and the size of the inductive coupling pillars. When all coupling values ​​match the coupling matrix, the duplexer will achieve the desired frequency band response.

[0031] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A three-band duplexer design method based on dielectric waveguides, characterized in that, Includes the following steps: S1. Synthesize the initial polynomials for the TX and RX channels according to the design specifications, and map the polynomials to the normalized frequency domain of the duplexer. S2. Solve for the iterative initial polynomial P of the three-band duplexer. t (s) and P r (s), where P t (s) = P TXn (s) · S RX (s) and P r (s) = P TXn (s) · S TX (s), the roots of the duplexer polynomial D(s) are F TXn (s), F RXn The product of the roots of (s) and the zeros introduced by the common resonant junction determines the value; S3. Based on the definition of return loss, solve for the normalization coefficients of the three-band duplexer at the passband boundaries of TX and RX respectively. p 0t and p 0r Then, the duplexer polynomial D(s) is solved according to the law of conservation of energy, and one iteration is completed at this time; S4, Update S TX and S RX Before and after the update S TX and S RX Compare the roots respectively, if S TX and S RX If all roots converge to the specified level, the iteration ends; otherwise, repeat steps S2 and S3 until the roots converge to the specified level. S5. After iteration, solve for the coupling matrix of the duplexer.

2. The three-band duplexer design method based on dielectric waveguide according to claim 1, characterized in that, duplexer S The parameters are given by the polynomials N(s) and P. t (s), P r (s), D(s), and three normalization coefficients n 0、 p 0t and p 0 Confirmed: 。 3. The three-band duplexer design method based on dielectric waveguide according to claim 2, characterized in that, In step S1, the polynomials of the TX and RX filters are determined by the following equation: 。 4. The three-band duplexer design method based on dielectric waveguide according to claim 3, characterized in that, In step S4, the update is performed using the following formula. S TX and S RX : ； in c 0 represents the capacitance value.

5. A duplexer designed based on the method described in any one of claims 1 to 4, characterized in that, It includes a common cavity (1), and the two sides of the common cavity (1) are respectively connected to the TX channel and the RX channel.

6. The duplexer according to claim 5, characterized in that, The TX channel includes a first resonant cavity (2), a second resonant cavity (3), a third resonant cavity (4), a fourth resonant cavity (5), a fifth resonant cavity (6), and a sixth resonant cavity (7); the first resonant cavity (2), the second resonant cavity (3), and the third resonant cavity (4) are connected sequentially to one side of the common cavity (1); the fifth resonant cavity (6) and the fourth resonant cavity (5) are respectively connected to the second resonant cavity (3) and the third resonant cavity (4); the sixth resonant cavity (7) is connected to the fifth resonant cavity (6).

7. The duplexer according to claim 6, characterized in that, The RX channel includes a seventh resonant cavity (8), an eighth resonant cavity (9) and a ninth resonant cavity (9); the seventh resonant cavity (8) is connected to the other side of the common cavity (1); the eighth resonant cavity (9) is connected to the seventh resonant cavity (8), and the ninth resonant cavity (9) is connected to the eighth resonant cavity (9).

8. The duplexer according to claim 7, characterized in that, The sixth resonant cavity (7), the ninth resonant cavity (9), and the common cavity (1) are all provided with ports (10).

9. The duplexer according to claim 8, characterized in that, The second resonant cavity (3), the third resonant cavity (4), the fourth resonant cavity (5) and the fifth resonant cavity (6) are arranged in a grid pattern, and adjacent resonant cavities are interconnected.

10. The duplexer according to claim 9, characterized in that, The common cavity (1), the seventh resonant cavity (8), the eighth resonant cavity (9) and the ninth resonant cavity (9) are arranged in a grid pattern.

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