A filter power divider with high selectivity

Abstract

The embodiment of the application provides a filter power divider with high selectivity, comprising: an input port, a first output structure, a second output structure, a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth cavity, a first resonant cavity cascade structure, a second resonant cavity cascade structure and a seventh resonant cavity; the input port is connected with the first resonant cavity through a coupling structure, the first resonant cavity is connected with the second resonant cavity through a coupling structure, and the first side of the third resonant cavity is connected with the second resonant cavity through a coupling structure; the first side of the fourth cavity is connected with the second side of the third resonant cavity through a coupling structure, the second side of the fourth cavity is connected with the first resonant cavity cascade structure, the third side of the fourth cavity is connected with the second resonant cavity cascade structure, and the fourth side of the fourth cavity is connected with the seventh resonant cavity; the first resonant cavity cascade structure is connected with the first output structure, and the second resonant cavity cascade structure is connected with the second output structure, so that miniaturization, low loss and high selectivity of filter power integration design are realized.

Description

Technical Field

[0001] This application relates to the field of power divider technology, and in particular to a power divider with high selectivity. Background Technology

[0002] With the rapid development of modern wireless communication technology, microwave and millimeter-wave technologies have been widely adopted in both civilian and military fields, with applications spanning satellite communication, radar detection, precision guidance, mobile communication, and medical treatment. As a core component of wireless communication systems, the performance of the radio frequency (RF) front-end directly determines the communication quality of the entire system. In the RF front-end circuit, filters and power dividers are indispensable components. Filters are used to select the desired frequency signal and suppress out-of-band interference, while power dividers are used to distribute the input signal into multiple outputs. In traditional solutions, filters and power dividers are typically cascaded as independent devices via transmission lines. However, this cascading method suffers from drawbacks such as large circuit size, high insertion loss accumulation, and increased design costs, making it difficult to meet the urgent demands of modern communication systems for miniaturization and high performance.

[0003] Filtering power dividers (FPDs), as devices that integrate filtering and power division functions, can perform filtering response while achieving power distribution, avoiding the size and loss problems caused by additional cascaded filters. Therefore, they have become an important means of realizing miniaturized RF front-ends. Waveguide structures are widely used in microwave and millimeter-wave filtering power divider designs due to their inherent advantages such as low loss, high power capacity, and high quality factor. Among them, cavity waveguides, as a classic waveguide transmission structure, have outstanding advantages such as robust structure, mature fabrication, and stable performance, making them particularly irreplaceable in high-power and millimeter-wave frequency band applications.

[0004] However, existing waveguide-structured power dividers still have significant shortcomings in achieving high frequency selectivity. Power dividers using traditional planar transmission line structures (such as microstrip lines and coplanar waveguides) have low quality factors and limited out-of-band rejection capabilities. They typically require increasing the filter order or introducing cross-coupling to construct transmission zeros to obtain steep passband edges, but this significantly increases circuit area and introduces additional insertion loss, contradicting the design goals of miniaturization and low loss. While power dividers using cavity waveguide structures offer advantages in low loss and high power capacity, the introduction of transmission zeros often relies on complex inter-cavity coupling, high-order mode excitation, or additional coupling structures. The design process is cumbersome and sensitive to fabrication precision, making it difficult to achieve a good balance between steep stopband attenuation and engineering yield. Furthermore, existing solutions generally lack effective means to flexibly control the position of transmission zeros using non-resonant nodes or signal reflection paths, making it difficult to achieve an ideal trade-off between out-of-band rejection performance and passband transmission efficiency. Summary of the Invention

[0005] This application provides a highly selective filter power divider to address the shortcomings of existing filter power dividers, such as insufficient frequency selectivity, complex design, and performance trade-offs. The power divider includes: an input port, a first output structure, a second output structure, a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth cavity, a cascaded structure of the first resonant cavity, a cascaded structure of the second resonant cavity, and a seventh resonant cavity.

[0006] The input port is connected to the first side of the first resonant cavity via a coupling structure;

[0007] The second side of the first resonant cavity is connected to the first side of the second resonant cavity through a coupling structure, and the second side of the second resonant cavity is connected to the first side of the third resonant cavity through a coupling structure.

[0008] The first side of the fourth cavity is connected to the second side of the third resonant cavity through a coupling structure; the second side of the fourth cavity is connected to the cascaded structure of the first resonant cavity; the third side of the fourth cavity is connected to the cascaded structure of the second resonant cavity; and the fourth side of the fourth cavity is connected to the seventh resonant cavity.

[0009] The first resonant cavity cascade structure is connected to the first output structure, and the second resonant cavity cascade structure is connected to the second output structure.

[0010] Optionally, the fourth cavity is a non-resonant cavity.

[0011] Optionally, the first resonant cavity cascade structure and the second resonant cavity cascade structure are symmetrical about the fourth cavity, and the first resonant cavity cascade structure and the second resonant cavity cascade structure are completely identical. The first resonant cavity cascade structure is composed of a fifth resonant cavity and a sixth resonant cavity cascaded and coupled together.

[0012] Optionally, the first resonant cavity, the second resonant cavity, and the third resonant cavity constitute an input-side filter cascade; the fifth resonant cavity and the sixth resonant cavity constitute an output-side filter cascade; the input-side filter cascade and the output-side filter cascade are separated by the fourth cavity as the dividing point.

[0013] Optionally, the first output structure and the second output structure are symmetrical about the fourth cavity, and the first output structure and the second output structure are completely identical. The first output structure includes a first output port and an eighth resonant cavity, and the eighth resonant cavity is connected to the first output port through a coupling structure. The second output structure includes a second output port and an eighth resonant cavity, and the eighth resonant cavity is connected to the second output port through a coupling structure.

[0014] Optionally, the coupling structure is an H-plane coupling window structure.

[0015] Optionally, the H-plane coupling window is a rectangular coupling window opened on the common wall of two adjacent cavities; the width and height of the rectangular coupling window are set according to the required coupling amount between the adjacent cavities.

[0016] Optionally, the power divider is divided into an upper half and a lower half using an H-plane partitioning method;

[0017] The upper part and the lower part are independently machined using CNC milling technology. After machining, the upper part and the lower part are aligned and fitted together along the H-plane split surface and connected by fasteners to form a complete closed waveguide cavity structure.

[0018] This application provides a highly selective filter power divider, comprising: an input port, a first output structure, a second output structure, a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth cavity, a cascaded structure of the first resonant cavity, a cascaded structure of the second resonant cavity, and a seventh resonant cavity; the input port is connected to a first side of the first resonant cavity via a coupling structure; the second side of the first resonant cavity is connected to a first side of the second resonant cavity via a coupling structure, and the second side of the second resonant cavity is connected to a first side of the third resonant cavity via a coupling structure; the first side of the fourth cavity is connected to a second side of the third resonant cavity via a coupling structure, the second side of the fourth cavity is connected to the cascaded structure of the first resonant cavity, the third side of the fourth cavity is connected to the cascaded structure of the second resonant cavity, and the fourth side of the fourth cavity is connected to the seventh resonant cavity; the cascaded structure of the first resonant cavity is connected to the first output structure, and the cascaded structure of the second resonant cavity is connected to the second output structure, thereby improving frequency selectivity. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 An air model diagram of a highly selective filter power divider provided for embodiments of this application;

[0021] Figure 2 The S-parameter simulation diagram of a highly selective filter power divider provided in the embodiments of this application.

[0022] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0025] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0026] In microwave RF circuits, power dividers have become key components for miniaturized RF front-ends because they combine filtering and power distribution functions and can effectively reduce circuit size and system losses.

[0027] In existing power divider designs, to achieve high frequency selectivity, a steep attenuation transition at the passband edge is typically required. However, traditional planar transmission line structures (such as microstrip lines and coplanar waveguides) have low quality factors and limited out-of-band rejection capabilities. This often necessitates increasing the filter order or introducing cross-coupling to construct transmission zeros, which significantly increases circuit area and introduces additional insertion loss, hindering system miniaturization and low-loss requirements. While waveguide-based power dividers offer advantages in low loss and high power capacity, introducing transmission zeros often relies on complex inter-cavity coupling or high-order mode excitation, making the design process cumbersome and sensitive to fabrication precision. A good balance between steep stopband attenuation and engineering yield is difficult to achieve. Furthermore, existing solutions lack effective measures for flexibly adjusting the zero position using non-resonant nodes or signal reflection paths, making it difficult to achieve an ideal trade-off between out-of-band rejection performance and passband transmission efficiency.

[0028] To address the aforementioned issues, this application proposes a highly selective filter power divider. Without increasing the number of circuit stages or physical size, it significantly improves frequency selectivity by introducing a secondary reflection path and a non-resonant cavity, allowing for flexible configuration of multiple transmission zeros on both sides of the passband. Simultaneously, this application fully utilizes the inherent low-loss characteristics of waveguide structures, combined with the independent phase and amplitude control capabilities of the non-resonant cavity. This avoids the increased area and loss associated with higher-order filters and simplifies the design freedom of transmission zeros. It effectively overcomes the shortcomings of existing filter power dividers, such as insufficient selectivity, complex design, and performance trade-offs, achieving a miniaturized, low-loss, and highly selective integrated filter power divider design.

[0029] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0030] Figure 1 An air model diagram of a highly selective filter power divider provided for an embodiment of the application. (e.g.) Figure 1 As shown, the highly selective filter power divider provided in this embodiment includes: an input port 1, a first output structure, a second output structure, a first resonant cavity 1, a second resonant cavity 2, a third resonant cavity 3, a fourth cavity 4, a cascaded structure of the first resonant cavities, a cascaded structure of the second resonant cavities, and a seventh resonant cavity 7. The fourth cavity 4 is a non-resonant cavity. The input port 1 is a WR-10 standard waveguide interface.

[0031] In this embodiment, the input port port1 is connected to the first side of the first resonant cavity 1 through a coupling structure; the second side of the first resonant cavity 1 is connected to the first side of the second resonant cavity 2 through a coupling structure, the second side of the second resonant cavity 2 is connected to the first side of the third resonant cavity 3 through a coupling structure; the first side of the fourth cavity 4 is connected to the second side of the third resonant cavity 3 through a coupling structure, the second side of the fourth cavity 4 is connected to the cascaded structure of the first resonant cavity, the third side of the fourth cavity 4 is connected to the cascaded structure of the second resonant cavity, and the fourth side of the fourth cavity 4 is connected to the seventh resonant cavity 7.

[0032] Specifically, the coupling structure is an H-plane coupling window structure, which is a rectangular coupling window opened on the common wall of two adjacent cavities. The width and height of the rectangular coupling window are set according to the required coupling amount between the adjacent cavities. The larger the electromagnetic coupling path area of ​​the window, the higher the coupling coefficient.

[0033] In this embodiment, the first resonant cavity cascade structure and the second resonant cavity cascade structure are symmetrical about the fourth cavity 4. The first resonant cavity cascade structure and the second resonant cavity cascade structure are completely identical. The first resonant cavity cascade structure is composed of the fifth resonant cavity 5 and the sixth resonant cavity 6 cascaded and coupled.

[0034] In this embodiment, the first resonant cavity 1, the second resonant cavity 2, and the third resonant cavity 3 constitute an input-side filter cascade; the fifth resonant cavity 5 and the sixth resonant cavity 6 constitute an output-side filter cascade; the input-side filter cascade and the output-side filter cascade are separated by the fourth cavity 4 as the dividing point.

[0035] In this embodiment, the first output structure and the second output structure are symmetrical about the fourth cavity 4, and the first output structure and the second output structure are identical. The first output structure includes a first output port 2 and an eighth resonant cavity 8, which is connected to the first output port 2 through a coupling structure. The second output structure includes a second output port 3 and an eighth resonant cavity 8, which is connected to the second output port 3 through a coupling structure. Both the first output port 2 and the second output port 3 are WR-10 standard waveguide interfaces.

[0036] Specifically, the power divider adopts a symmetrical topology centered on the fourth cavity 4. The input port Port1 is connected to the first rectangular waveguide resonator via an H-plane coupling window. A first-stage H-plane coupling window is opened on the common H-plane wall of the first rectangular waveguide resonator and the second resonator 2, and a second-stage H-plane coupling window is opened on the common H-plane wall of the second resonator 2 and the third resonator 3. The width and height of the first-stage and second-stage H-plane coupling windows are independently set according to the coupling amount required for input-side cascading, ensuring continuous cascading of the three cavities along the same straight line. The signal is transmitted unidirectionally along a straight line on the input side without additional branches. An input-side H-plane coupling window is opened on the first sidewall of the fourth cavity 4, which connects with the output-side H-plane coupling window of the third resonator 3, forming the first path, i.e., the input coupling path. A second-stage H-plane coupling window is opened on the second sidewall of the fourth cavity 4. An output-side H-plane coupling window is connected to the fifth resonant cavity 5 of one output branch. The fifth resonant cavity 5 is connected to the sixth resonant cavity 6 via the H-plane coupling window. The sixth resonant cavity 6 is then connected to the corresponding output port via the H-plane coupling window, forming a second path, i.e., the first output coupling path. A second output-side H-plane coupling window is opened on the third side wall of the fourth cavity 4, connecting to the fifth resonant cavity 5 of the other output branch. The fifth resonant cavity 5 is connected to the sixth resonant cavity 6 via the H-plane coupling window. The sixth resonant cavity 6 is then connected to the corresponding output port via the H-plane coupling window, forming a third path, i.e., the second output coupling path. The first path, the second path, and the third path are spatially distributed in three directions, enabling the fourth cavity 4 to simultaneously perform the functions of single-channel signal input and two-channel signal distribution.

[0037] Furthermore, the fourth sidewall of the fourth cavity 4 is connected to the seventh resonant cavity 7 via an H-plane coupling window, and the sidewalls of the two output ports are connected to the two eighth resonant cavities 8 via H-plane coupling windows respectively. The seventh resonant cavity 7 and the eighth resonant cavity 8 generate a 180° phase difference at two points above and below the operating frequency band, thereby generating a transmission zero at a specific frequency, improving the matrix coefficient of the operating frequency band, and realizing selective control.

[0038] Specifically, the overall structure of this power divider adopts an H-plane splitting method, that is, the entire device is divided into upper and lower parts along the plane containing the wide side of the waveguide. The upper and lower parts are respectively machined by CNC milling with a chamfer of 0.2mm. The upper and lower parts are assembled by locating pins and screws to form a complete cavity structure. All inner walls of the resonant cavity and coupling window surfaces are surface treated to ensure conductivity and dimensional accuracy.

[0039] In this embodiment, the radio frequency signal is fed in through the input port Port1, enters the first rectangular waveguide resonant cavity through the input coupling window, and then enters the fourth cavity 4 after being filtered and cascaded through the second and third resonant cavities. The fourth cavity 4 is a non-resonant cavity, and its geometric center serves as the center of symmetry of the overall structure. This cavity also serves as a power distribution node and a T-shaped coupling node.

[0040] The fourth cavity 4 distributes the input signal along two symmetrical output branches, both of which have identical structures. Taking the first output port (Port2) as an example, the fourth cavity 4 is connected to the fifth resonant cavity 5 via an H-plane coupling window. The fifth resonant cavity 5 is connected to the sixth resonant cavity 6 via an H-plane coupling window, and the sixth resonant cavity 6 is then connected to the output port via an H-plane coupling window. The seventh resonant cavity 7 and the eighth resonant cavity 8 are connected to the fourth cavity branch and the output branch. Utilizing the principle of reflection, by controlling the dimensions of the seventh and eighth resonant cavities 7 and 8, their resonant frequencies can be controlled, achieving a 180° phase reversal. This phase cancellation generates a transmission zero. The two transmission zeros are located on opposite sides of the passband, jointly enhancing the out-of-band rejection capability of the power divider. The first to third resonant cavities on the input side and the fifth to sixth resonant cavities on the output side together constitute a complete filtering response.

[0041] Since the two output branches are in a completely symmetrical topology centered on the fourth cavity 4, the input signal is equally divided into two signals with consistent amplitude and phase at the fourth cavity 4, which are output from the first output port Port2 and the second output port Port3, respectively. The coupling between each resonant cavity is achieved using H-plane coupling windows. By adjusting the size of each coupling window, the amount of coupling between cavities is controlled, thereby achieving the preset bandpass filtering response and low-loss signal transmission within the passband.

[0042] Figure 2 The S-parameter simulation diagram of a highly selective filter power divider provided in the embodiments of this application is shown. Figure 2 As shown, the operating frequency of this filter power divider is 80GHz-85.5GHz. There are obvious transmission zeros 2GHz away from the upper and lower passbands, and six reflection zeros within the passband are clearly identifiable. The input return loss S(1,1) within the passband is better than 19 dB, and the insertion losses S(2,1) and S(3,1) (due to the symmetrical structure of this filter power divider, a 3dB power division is achieved) Figure 2 (S(2,1) and S(3,1) are represented by the same line segment) is better than 3.6 dB.

[0043] This application provides a highly selective filter power divider, designed and manufactured using CNC machining methods, and utilizing TM... 101 The mode resonates, and cavity coupling is achieved using an H-plane window. A transmission zero is obtained by introducing a non-resonant cavity; the position of the transmission zero can be adjusted by regulating the size of the resonant cavity in the non-resonant cavity branch, resulting in high selectivity in the stopband and superior filtering performance. Adjusting the size of the H-plane coupling window yields the desired passband insertion loss and bandwidth.

[0044] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0045] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A highly selective filter power divider, characterized in that, include: Input port, first output structure, second output structure, first resonant cavity, second resonant cavity, third resonant cavity, fourth cavity, cascaded structure of first resonant cavity, cascaded structure of second resonant cavity, and seventh resonant cavity; The input port is connected to the first side of the first resonant cavity via a coupling structure; The second side of the first resonant cavity is connected to the first side of the second resonant cavity through a coupling structure, and the second side of the second resonant cavity is connected to the first side of the third resonant cavity through a coupling structure. The first side of the fourth cavity is connected to the second side of the third resonant cavity through a coupling structure; the second side of the fourth cavity is connected to the cascaded structure of the first resonant cavity; the third side of the fourth cavity is connected to the cascaded structure of the second resonant cavity; and the fourth side of the fourth cavity is connected to the seventh resonant cavity. The first resonant cavity cascade structure is connected to the first output structure, and the second resonant cavity cascade structure is connected to the second output structure.

2. A highly selective filter power divider according to claim 1, characterized in that, The fourth cavity is a non-resonant cavity.

3. A highly selective filter power divider according to claim 1, characterized in that, The first resonant cavity cascaded structure and the second resonant cavity cascaded structure are symmetrical about the fourth cavity. The first resonant cavity cascaded structure and the second resonant cavity cascaded structure are completely identical. The first resonant cavity cascaded structure is composed of a fifth resonant cavity and a sixth resonant cavity cascaded and coupled together.

4. A highly selective filter power divider according to claim 3, characterized in that, The first resonant cavity, the second resonant cavity, and the third resonant cavity constitute an input-side filter cascade; the fifth resonant cavity and the sixth resonant cavity constitute an output-side filter cascade; the input-side filter cascade and the output-side filter cascade are respectively separated by the fourth cavity as the dividing point.

5. A highly selective filter power divider according to claim 1, characterized in that, The first output structure and the second output structure are symmetrical about the fourth cavity. The first output structure and the second output structure are completely identical. The first output structure includes a first output port and an eighth resonant cavity. The eighth resonant cavity is connected to the first output port through a coupling structure. The second output structure includes a second output port and an eighth resonant cavity. The eighth resonant cavity is connected to the second output port through a coupling structure.

6. A highly selective filter power divider according to claim 1, characterized in that, The coupling structure is an H-plane coupling window structure.

7. A highly selective filter power divider according to claim 6, characterized in that, The H-plane coupling window is a rectangular coupling window opened on the common wall of two adjacent cavities; the width and height of the rectangular coupling window are set according to the required coupling amount between the adjacent cavities.

8. A highly selective filter power divider according to claim 1, characterized in that, The filter power divider is divided into an upper half and a lower half using an H-plane partitioning method; The upper part and the lower part are independently machined using CNC milling technology. After machining, the upper part and the lower part are aligned and fitted together along the H-plane split surface and connected by fasteners to form a complete closed waveguide cavity structure.

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