High-selectivity one-to-four filtering power divider based on stub loaded resonators and T-shaped E-plane stepped waveguides

Abstract

The invention provides a high-selectivity one-to-four filtering power divider based on stub loaded resonators and T-shaped E-plane stepped waveguides, which relates to the technical field of filtering power dividers and comprises a third-order stub filter and a four-way power divider. An input signal firstly passes through the third-order stub filter and then is divided into four paths of output signals through the four-path power divider. Through the synergistic effect of the stub loaded resonators and the E-plane stepped waveguides, six transmission zeros can be generated on the two sides of a Ku wave band pass band, the steepness of the edge of the pass band reaches-40 dB or below, pass band and stop band signals are effectively distinguished, the frequency selectivity is improved, and the problems that in the prior art, the pass band transition bandwidth is large, and interference suppression is poor are solved.

Description

Technical Field

[0001] This invention relates to the technical field of power dividers, and more particularly to a highly selective one-to-four power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide. Background Technology

[0002] With the increasing application of Ku-band (12-18GHz) technology in fields such as satellite communication and millimeter-wave radar, higher demands are being placed on the performance of filtering power dividers. Currently, traditional filtering power divider technologies are mainly divided into two categories: microstrip / stripline structures and waveguide structures. Microstrip / stripline structure filtering power dividers are widely used in low-frequency bands due to their simple structure and ease of fabrication. However, in the Ku-band, this structure faces significant dielectric and radiation losses, resulting in excessively high insertion loss, making it difficult to meet low-loss requirements. Simultaneously, its out-of-band rejection capability is weak, failing to effectively suppress interference signals outside the passband and hindering high selectivity. Furthermore, as the frequency increases, parasitic effects become more pronounced, making precise control of transmission zeros difficult, and preventing the formation of multiple transmission zeros to enhance filtering characteristics. While waveguide structure filtering power dividers offer advantages such as large power capacity and relatively low loss, the traditional H-plane or E-plane waveguide T-junction design is prone to mode interference during power division, leading to increased signal transmission non-uniformity and failing to achieve ideal power distribution. Moreover, this type of structure lacks flexible filtering characteristic design methods, making it difficult to effectively generate multiple transmission zeros on both sides of the passband. Its out-of-band suppression performance is insufficient, failing to meet the strong out-of-band suppression requirements of modern communication systems. Furthermore, the waveguide structure is relatively large, hindering the miniaturization and integration of equipment.

[0003] In summary, existing filter power divider technologies suffer from several drawbacks, including difficulty in simultaneously achieving low loss and high selectivity, inability to generate multiple transmission zeros, weak out-of-band rejection, and limitations in miniaturization. This invention, based on a stub-loaded resonator and an E-plane stepped waveguide T-structure, aims to overcome these shortcomings and provide an innovative design method for Ku-band filter power dividers that combines high selectivity, multiple transmission zeros, low loss, and strong out-of-band rejection. Summary of the Invention

[0004] Based on the stringent performance requirements of Ku-band communication systems for power dividers in terms of high selectivity, low loss, and strong out-of-band suppression, and considering the technical problems existing in this frequency band, this invention provides a high-selectivity 1-to-4 power divider based on a stub-loaded resonator and a T-shaped E-plane stepped waveguide. This invention proposes an integrated power divider design based on a stub-loaded resonator and a T-shaped E-plane stepped waveguide, achieving integrated performance of high selectivity, multiple transmission zeros, low insertion loss, and strong out-of-band suppression, aiming to significantly improve the overall performance of the Ku-band RF front-end.

[0005] The technical means employed in this invention are as follows: A highly selective 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide includes: a third-order stub filter and a four-way power divider; the input signal first passes through the third-order stub filter, and then passes through the four-way power divider to split the input signal into four output signals; The third-order stub filter includes: three resonators, six stubs, one input port I, and one output port I; in the third-order stub filter, a stub is loaded at each end of each resonator; The four-way power divider includes four main waveguides, three branches, one input port II, and four output ports II. The four-way power divider uses an E-plane T-junction and stepped waveguide structure as the main channels for power distribution and transmission. The initial length of the four main waveguides is twice the wavelength, and the length of the three branches is one wavelength.

[0006] Furthermore, the length of each of the three resonators is one wavelength.

[0007] Furthermore, both the input port I and the output port I are WR-62 standard waveguides with a length of 10mm.

[0008] Furthermore, the input port II of the four-way power divider is a WR-62 waveguide.

[0009] Furthermore, the six stubs form six transmission zeros on both sides of the passband, making the passband edge steepness reach below -40dB.

[0010] Furthermore, the three resonators generate three poles through coupling, and the passband width can be stabilized at 2GHz and the center frequency locked at 16.2GHz by adjusting the coupling strength.

[0011] Compared with the prior art, the present invention has the following advantages: 1. High selectivity and multiple transmission zeros: The synergistic effect of the stub-loaded resonator and the E-plane stepped waveguide can generate six transmission zeros on both sides of the Ku-band passband, making the passband edge steepness reach below -40dB, effectively distinguishing the passband and stopband signals, improving frequency selectivity, and solving the problems of poor passband transition bandwidth and interference suppression in existing technologies.

[0012] 2. Low loss: The E-plane stepped waveguide serves as the main transmission structure, resulting in low metal and dielectric losses. The stub-loaded resonator reduces additional losses through optimized coupling design, achieving an overall insertion loss of less than -6.5dB within the Ku-band passband, which is superior to the high high-frequency loss defect of traditional microstrip filter power dividers.

[0013] 3. Strong out-of-band suppression: The transmission null distribution and the mode suppression characteristics of the E-plane stepped waveguide enable the passband edge steepness to reach below -40dB, significantly attenuating out-of-band interference signals and achieving deep suppression at specific out-of-band frequencies in the Ku band (such as adjacent channels and spurious frequencies in satellite communication), meeting the requirements of high electromagnetic compatibility systems.

[0014] 4. Superior power divider performance: The T-type E-plane stepped waveguide structure is optimized and combined with the signal shaping effect of the resonator to ensure that the amplitude difference of the power divider output is less than ±0.5dB, solving the problem of uneven power distribution in traditional power dividers and adapting to Ku-band multi-channel, highly coordinated RF systems. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0016] Figure 1 This is a three-dimensional structural diagram of a T-type filter power divider based on a stub-loaded resonator and an E-plane stepped waveguide, provided in an embodiment of the present invention. The dimensions are: a = 15.798 mm, b = 7.899 mm, L0 = 10 mm, L = 37 mm, L2 = 18.5 mm, L1 = 16.7 mm, d1 = 7.3 mm, d2 = 7.2 mm, d3 = 6.5 mm, d4 = 6.7 mm, S1 = 1.6 mm, S2 = 6.2 mm, S3 = 2 mm, S4 = 6.7 mm, S5 = 1.1 mm, S6 = 7.1 mm, t = 2 mm, b1 = 9.399 mm, b2 = 5.76 mm, b3 = 3.76 mm, b4 = 1.88 mm, b5 = 2.08 mm, b6 = 1.97 mm, b7 = 2.03 mm. Figure 2 The diagram shows the three-dimensional structure of a third-order resonator based on a stub load, where a = 15.798 mm, b = 7.899 mm, L = 9.399 mm, L0 = 10 mm, L1 = 16.7 mm, S1 = 1.6 mm, S2 = 6.2 mm, S3 = 2 mm, S4 = 6.7 mm, S5 = 1.1 mm, S6 = 7.1 mm, d1 = 7 mm, d2 = 6.8 mm, d3 = 6.5 mm, and d4 = 6.4 mm. Figure 3 The S11 and S21 parameter curves of a third-order stub-loaded resonator; Figure 4A three-dimensional structural diagram of a four-way stepped waveguide traveling wave power divider / combiner is shown, where a=15.798mm, b=7.899mm, L1=37mm, L2=18.5mm, b1=5.76mm, b2=3.76mm, b3=1.88mm, b4=2.08mm, b5=1.97mm, and b6=2.03mm. Figure 5 A schematic model of a four-way power divider circuit; Figure 6 The S11 curve of the return loss of a four-way stepped waveguide traveling wave power divider / synthesizer; Figure 7 The transmission coefficient S21-S51 curves for a four-way stepped waveguide traveling wave power divider / synthesizer; Figure 8 Isolation curves for a four-way stepped waveguide traveling wave power distributor / synthesizer; Figure 9 The curve showing the return loss S11 at the input port of the power divider filter according to an embodiment of the present invention; Figure 10 The output port transmission coefficient curves S21-S51 of the power divider in this embodiment of the invention are shown, with S41 and S51 basically overlapping. Figure 11 The isolation curves for output ports 2, 3, 4, and 5 of the filter power divider in this embodiment of the invention are shown. S42 and S52 are basically overlapping. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0018] It should be noted that the terms "first," "second," etc., 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 the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0019] To address the stringent performance requirements of Ku-band communication systems for power dividers in terms of high selectivity, low loss, and strong out-of-band suppression, and considering the performance bottlenecks of existing technologies in this frequency band, this invention proposes an integrated power divider design based on an E-plane T-junction and a stepped waveguide structure. By loading a resonator with a stub, it achieves integrated performance characteristics of high selectivity, multiple transmission zeros, low insertion loss, and strong out-of-band suppression, aiming to significantly improve the overall performance of the Ku-band RF front-end.

[0020] like Figure 1-11 As shown, this invention provides a highly selective 1-to-4 filter power divider based on stub-loaded resonators and T-shaped E-plane stepped waveguides, comprising: a third-order stub filter and a four-way power divider. The input signal first passes through the third-order stub filter, and then the four-way power divider splits the input signal into four output signals. The third-order stub filter includes three resonators, six stubs, one input port, and one output port. The length of each of the three resonators is one wavelength, and a stub is loaded at each end of each resonator. The input and output ports use WR-62 standard waveguides with a length of 10 mm. The four-way power divider includes four main waveguide segments, three branches, one input port, and four output ports. The four main waveguide segments use an E-plane T-junction and stepped waveguide structure as the main channels for power distribution and transmission. The initial length of the four main waveguide segments is twice the wavelength, and the length of the three branches is one wavelength. The input port of the four-way power divider uses a WR-62 waveguide.

[0021] In a preferred embodiment of this application, the power divider is based on an E-plane T-junction and a stepped waveguide structure, integrating a stub-loaded resonator to achieve deep synergy between filtering and power division functions. The T-shaped E-plane stepped waveguide structure of the four-way power divider serves as the main channel for power distribution and transmission. The stepped waveguide design, with its gradually changing cross-sectional dimensions across four main waveguide segments, fully leverages the inherent advantages of E-plane waveguides in power equalization. Through precise adjustment of the stepped structure, ideal characteristic impedance matching can be achieved, further optimizing the amplitude and phase consistency of the two output signals. Simultaneously, by utilizing the gradient change in waveguide cross-sectional dimensions, the characteristic impedance can be effectively adjusted. 10 By optimizing the transmission characteristics of the mode, the reflection loss and mode conversion loss at the T-junction are reduced, meeting the requirements for low-loss design. Based on the transmission characteristics of Ku-band electromagnetic waves, the dual objectives of impedance matching and power sharing can be achieved by accurately calculating the width, length, and height parameters of different step segments.

[0022] The third-order stub filter constructs resonant units by loading stubs with differentiated parameters at specific locations on the resonator, forming a cooperative working mechanism with the main waveguide. Based on a rectangular waveguide cavity resonator, this design integrates six capacitive stubs at the cavity end, generating six adjustable transmission zeros without increasing circuit size. Due to specific electromagnetic coupling between stubs of different positions and lengths, transmission zeros can be formed outside the passband when the stub parameters (length, width, and distance from the main waveguide) are matched. The core principle lies in the interference effect between the resonant modes of the stubs and the transmission modes of the main waveguide, causing significant attenuation of signals at specific stopband frequencies. Through simulation optimization of the spatial layout of the six stubs, six transmission zeros can be constructed on both sides of the passband, achieving a passband edge steepness below -40dB, significantly improving filter selectivity and achieving precise suppression of out-of-band interference. The three resonators generate three poles through coupling; by adjusting the coupling strength, the passband width can be stabilized at 2GHz, and the center frequency locked at 16.2GHz.

[0023] The synergistic effect of the third-order stub filter and the four-way power divider: By combining the output port of the third-order stub filter with the input port of the four-way power divider, an integrated design of the two is achieved. The E-plane stepped waveguide structure of the four-way power divider induces electromagnetic wave reflection and mode conversion, an effect that synergizes with the characteristics of the third-order stub filter. The reflected signal generated by the stepped waveguide structure of the four-way power divider superimposes with the resonant signal of the resonator in the third-order stub filter, enhancing both the transmission efficiency of the signal within the passband and the suppression capability of the stopband signal. Simultaneously, the stepped structure of the four-way power divider reduces out-of-band spurious mode interference by suppressing higher-order modes, significantly improving out-of-band suppression performance and achieving a deep integration of filtering and power-dividing functions. Specifically, the signal transmission process is as follows: After the Ku-band input signal enters the main waveguide, it first undergoes preliminary filtering and frequency selection through a third-order stub filter to select the target passband signal. Subsequently, power distribution is achieved through the E-plane T-junction and stepped waveguide structure of the four-way power divider. At the same time, the electromagnetic coupling effect between the stepped waveguide structure of the four-way power divider and the resonator in the third-order stub filter is used to perform secondary optimization of the signal spectrum, suppressing out-of-band residual interference, and finally outputting a multi-channel signal with high selectivity, low loss, and strong out-of-band suppression.

[0024] Figure 2This is a 3D structure diagram of a third-order stub-loaded resonator, consisting of three resonators and six stubs. The three resonators generate three poles within the passband, achieving the designed passband size of 2 GHz. The six stubs generate six transmission zeros on both sides of the antenna passband gain. By changing the length of the stubs, the transmission zeros can be independently tuned to the frequency of interest. The dimensions of the stubs are determined to be S1 = 1.6 mm, S2 = 6.2 mm, S3 = 2 mm, S4 = 6.7 mm, S5 = 1.1 mm, and S6 = 7.1 mm.

[0025] The two resonators are coupled through a capacitive window. Two split resonant frequencies can be utilized ( and The coupling coefficient is determined by the following relationship ( ): ; Coupling coefficient ( ) , , , It increases with the increase. In the calculation Adjustment The value to be The frequency is maintained at 16.2 GHz, and the coupled resonator is weakly coupled at the input / output ports. Using this technique, the calculated values ​​of the proposed circularly polarized filtered antenna can be extracted. The dimensions corresponding to the values ​​are respectively =7mm, =6.8mm, =6.5mm, =6.4mm.

[0026] Figure 3 The S11 and S21 parameter curves of a third-order stub-loaded resonator with a bandwidth of 2GHz are shown. Within the bandwidth, the three resonators generate three poles. The S11 parameter in the passband is less than -15dB. The six stubs generate six zeros outside the broadband, making the passband edge steepness below -40dB, effectively distinguishing passband and stopband signals and improving frequency selectivity. Figure 4 This is a 3D structural diagram of a four-way stepped waveguide traveling wave power divider / combiner, employing a T-type E-plane stepped waveguide power divider. The key to this design lies in the accurate calculation of the waveguide structure with specific characteristic impedances. Using the formula: , The waveguide width and height corresponding to the required characteristic impedance can be obtained. The power combiner designed in this invention operates at a frequency of 16.2 GHz, and the input port uses a standard WR-62 waveguide (wide side a = 15.798 mm, narrow side b = 7.899 mm). Its equivalent characteristic impedance is calculated to be... =232.5Ω.

[0027] according to Figure 5 A circuit principle model of a four-way power divider was obtained, and a set of characteristic impedances were obtained respectively. = The waveguide heights of 2Zo and 3Zo are determined. The four main waveguides in the power divider are all L1=37mm, and the narrow sides of the stepped waveguides are b=7.899mm, b1=5.76mm, b2=3.76mm, and b3=1.88mm, respectively. The lengths of the three side branches are all L2=18.5mm, the width is a=15.798mm, and the narrow sides are b4=2.08mm, b5=1.97mm, and b6=2.03mm, respectively.

[0028] Figure 6 The return loss S11 curve for the four-way stepped waveguide traveling wave power divider / synthesizer is shown. The results indicate that the return loss is less than -20dB within the design bandwidth, meeting the design target requirements. The values ​​are: a=15.798mm, b=7.899mm, L1=37mm, L2=18.5mm, b=7.899mm, b1=5.76mm, b2=3.76mm, b3=1.88mm, b4=2.08mm, b5=1.97mm, b6=2.03mm.

[0029] Figure 7 The transmission coefficient S21-S51 curves of the four-way stepped waveguide traveling wave power divider / synthesizer are shown. The results show that the transmission coefficient is about -6dB within the design bandwidth, which meets the design requirements.

[0030] Figure 8 The isolation curves for the four-way stepped waveguide traveling wave power divider / synthesizer are shown. The results indicate that the isolation of the output port is less than -11dB within the design bandwidth, which meets the design requirements.

[0031] Figure 9The input port return loss S11 curve of the filter power divider in this embodiment of the invention shows that the return loss is less than -15dB within the design bandwidth. The third-order filter in the first half generates three poles in the passband, which meets the design requirements. Among them, a=15.798mm, b=7.899mm, L=37mm, L0=10mm, L2=18.5mm, L1=18.5mm, d1=7.3mm, d2=7.2mm, d3=6.5mm, d4=6.7mm, S1=1.6mm, S2=6.2mm , S3=2mm, S4=6.7mm, S5=1.1mm, S6=7.1mm, t=2mm, b1=9.399mm, b2=5.76mm, b3=3.76mm, b4=1.88mm, b5=2.08mm, b6=1.97mm, b7=2.03mm.

[0032] Figure 10 The output port transmission coefficient curves S21-S51 of the power divider in this embodiment of the invention are shown. S41 and S51 are basically coincident, indicating a bandwidth of 2GHz and a transmission coefficient of approximately -6dB within the passband, meeting the design specifications. Six transmission zeros are generated on both sides of the passband, resulting in a passband edge steepness of less than -40dB, effectively distinguishing between passband and stopband signals and improving frequency selectivity.

[0033] Figure 11 The isolation curves for output ports 2, 3, 4, and 5 of the power divider in this embodiment of the invention are shown. S42 and S52 are basically overlapping. The results show that the isolation of the output ports is less than -10dB within the design bandwidth, which meets the design requirements.

[0034] In summary, a highly selective Ku-band filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide is provided. By loading six stubs onto the resonator, six transmission zeros are generated on both sides of the passband, resulting in a passband edge steepness of less than -40dB. This effectively distinguishes the passband and stopband signals, thereby achieving high selectivity, multiple transmission zeros, low loss, and strong out-of-band suppression.

[0035] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. It should be understood that the disclosed technical content in the several embodiments provided in this application can be implemented in other ways.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly selective 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide, characterized in that, include: Third-order stub filter and four-way power divider; The input signal first passes through the third-order stub filter, and then passes through the four-way power divider to split the input signal into four output signals; The third-order stub filter includes: three resonators, six stubs, one input port I, and one output port I; In the third-order stub filter, a stub is applied to both ends of each resonator; The four-way power divider includes four main waveguides, three branches, one input port II, and four output ports II. The four-way power divider uses an E-plane T-junction and stepped waveguide structure as the main channels for power distribution and transmission. The initial length of the four main waveguides is twice the wavelength, and the length of the three branches is one wavelength.

2. The high-selectivity 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide according to claim 1, characterized in that, The length of each of the three resonators is one wavelength.

3. A high-selectivity 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide according to claim 1, characterized in that, Both the input port I and the output port I are WR-62 standard waveguides with a length of 10mm.

4. A high-selectivity 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide according to claim 1, characterized in that, The input port II of the four-way power divider is a WR-62 waveguide.

5. A high-selectivity 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide according to claim 1, characterized in that, The six stubs form six transmission zeros on both sides of the passband, making the passband edge steepness below -40dB.

6. A high-selectivity 1-to-4 filter power divider based on a stub-loaded resonator and a T-type E-plane stepped waveguide according to claim 1 or 2, characterized in that, The three resonators generate three poles through coupling. By adjusting the coupling strength, the passband width can be stabilized at 2 GHz, and the center frequency can be locked at 16.2 GHz.

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