Rectangular waveguide microstrip power divider

Abstract

The invention discloses a rectangular waveguide microstrip power divider, relates to the field of microwave devices, and solves the problem of insufficient power processing capability in the prior art. The key points of the technical scheme are as follows: a microstrip probe is suspended on each of an upper waveguide body and a lower waveguide body along the direction of the center line of the wide side of the rectangular waveguide; wherein the micro-strip probes suspended on the upper waveguide body and the lower waveguide body form a face-to-face double-probe structure by taking the center line of the wide side of the rectangular waveguide as a symmetry plane; waveguide isolation structures are formed on the end faces of the two microstrip probes and used for absorbing mutual coupling signals generated by the double-probe structure.

Description

Technical Field

[0001] This invention relates to the field of microwave devices, and more specifically, to a rectangular waveguide microstrip power divider. Background Technology

[0002] Microwaves are electromagnetic waves with wavelengths between 1 m and 1 mm, corresponding to frequencies of 300 MHz to 300 GHz. Microwaves are the primary carrier of wireless information transmission today, widely used in communications, radar, electronic warfare, telemetry and remote sensing, and industrial production. Power dividers are among the most widely used devices in microwave circuits. Their main function is to split a microwave signal into two or more coherent signals of different power levels, and conversely, they can combine multiple microwave signals of different power levels into a single output. Throughout the entire process, the frequency of the microwave signal remains unchanged; only the amplitude and phase change.

[0003] Power dividers come in various circuit configurations, including Wilkinson bridges, Lange bridges, branch-line bridges, T-junctions, and Magic-T structures. Depending on the application requirements, they can be implemented independently or in combination using various microwave transmission lines such as microstrip lines, striplines, coaxial lines, coplanar waveguides, substrate-integrated waveguides, and rectangular waveguides. Among these, the hybrid power divider combining rectangular waveguides and microstrip lines offers unique advantages: the rectangular waveguide, as the main port, can carry high power, while the microstrip line branch ends facilitate the integration of semiconductor devices. This type of power divider typically achieves signal transition and power distribution simultaneously by symmetrically arranging multiple microstrip probes inside the waveguide. Due to its integrated transition and power division design, the waveguide-microstrip power divider offers significant advantages such as compact structure and low insertion loss.

[0004] Depending on the insertion position of the microstrip probes into the waveguide, various waveguide-microstrip power dividers can be formed. One typical structure involves symmetrically inserting two microstrip probes on the same wide side of a rectangular waveguide, with the center of the wide side of the waveguide as a mirror image, forming a face-to-face dual-probe structure. This structure distributes the microwave signal in the rectangular waveguide to the two microstrip lines in an equal-amplitude and in-phase manner. However, this conventional structure has significant limitations: although it achieves power distribution, the isolation between the two microstrip probes can theoretically only reach 6dB due to the lack of isolation circuit design. This performance deficiency makes it difficult to meet the requirements of applications such as phased array feeder networks, balanced mixers, and high-power combining systems.

[0005] Currently, several technologies exist for improving the isolation of rectangular waveguide-microstrip dual-probe power dividers. For example, Chinese patent CN113258244A proposes a rectangular waveguide-microstrip 0° phase difference high-isolation broadband power divider. This solution improves isolation performance by placing a non-contact thin-film resistor perpendicular to the end face of the microstrip probe within the rectangular waveguide, utilizing the thin-film resistor to absorb the vertical component of the coupled electric field between the two microstrip probes. However, this solution has two main technical drawbacks: 1) the isolation circuit uses a suspended structure, lacking an effective heat conduction path, resulting in limited power processing capability; 2) the non-contact resistor requires high precision, making structural implementation difficult and hindering mass production. Summary of the Invention

[0006] The purpose of this invention is to provide a rectangular waveguide microstrip power divider that solves the problem of insufficient power processing capability in existing technologies.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0008] This invention provides a rectangular waveguide microstrip power divider, which is divided into a mirror-symmetrical upper waveguide and a lower waveguide along the centerline of the wide side of the rectangular waveguide. A microstrip probe is suspended on each of the upper and lower waveguides along the centerline of the wide side of the rectangular waveguide. The microstrip probes suspended on the upper and lower waveguides form a face-to-face double-probe structure with the centerline of the wide side of the rectangular waveguide as the plane of symmetry.

[0009] Waveguide isolation structures are formed at the end faces of the two microstrip probes to absorb the mutual coupling signals generated by the dual-probe structure.

[0010] In one implementation, the waveguide isolation structure includes an H-plane waveguide, a bifurcated waveguide, and an AlN-based thin-film resistor.

[0011] In one implementation, an H-plane waveguide orthogonal to one end face of the microstrip probe is provided on the wide side of the rectangular waveguide to collect and conduct the mutual coupling signal generated by the dual-probe structure; wherein, the narrow side of the H-plane waveguide is parallel to the electric field lines of the mutual coupling signal generated by the dual-probe structure.

[0012] T-shaped bifurcations are made on the end faces of the two H-plane waveguides away from the microstrip probe, respectively, to form the bifurcated waveguides in the upper and lower waveguides.

[0013] The AlN-based thin-film resistor is horizontally disposed on the bifurcated waveguide to ultimately absorb the mutual coupling signal generated by the dual-probe structure.

[0014] In one implementation, the H-plane waveguide and the rectangular waveguide are orthogonal to each other.

[0015] In one implementation, a waveguide groove is formed in a rectangular waveguide on the back side of the microstrip probe; wherein the width of the waveguide groove is the same as the width of the rectangular waveguide.

[0016] In one implementation, a diaphragm is provided on the narrow sidewall of the H-plane waveguide.

[0017] In one implementation, coaxial connectors are fixed to the back of the upper and lower waveguides respectively by screws. The rectangular waveguide serves as the input end of the rectangular waveguide microstrip power divider, and the coaxial connector located between the upper and lower waveguides serves as the output end of the rectangular waveguide microstrip power divider.

[0018] In one implementation, the other side of the microstrip probe is converted into a 50Ω microstrip line via a high-impedance transformation line.

[0019] In one implementation, in a passive application, the end of the 50Ω microstrip line away from the microstrip probe is perforated to allow the inner conductor of the coaxial connector to pass through the back of the cavity and then be soldered.

[0020] In active applications, the end of the 50Ω microstrip line furthest from the microstrip probe is bonded to the MIC via a gold wire.

[0021] In one implementation, the microstrip probe is parallel to the centerline of the wide side of the rectangular waveguide.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention forms a waveguide isolation terminal consisting of an H-plane waveguide, a bifurcated waveguide, and an AlN-based thin-film resistor on the end faces of two microstrip probes, thereby improving the isolation of the rectangular waveguide microstrip power divider to over 15dB within a 20% relative bandwidth. Simultaneously, the AlN-based thin-film resistor, with its bottom surface in close contact with the metal cavity, absorbs mutually coupled signals, forming an efficient heat dissipation path and significantly improving power processing capability. Furthermore, the rectangular waveguide microstrip power divider provided by this invention has a simple structural fabrication and assembly process, enabling mass production. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of a rectangular waveguide microstrip power divider provided in an embodiment of the present invention;

[0026] Figure 2 This is a front view of a rectangular waveguide microstrip power divider provided in an embodiment of the present invention;

[0027] Figure 3The parameter simulation diagram of the rectangular waveguide microstrip power divider provided in the embodiment of the present invention is shown.

[0028] Figure labels and figure descriptions:

[0029] 1. Upper waveguide; 2. Lower waveguide; 3. Rectangular waveguide; 4. Coaxial connector; 5. Microstrip probe; 6. High impedance transformation line; 7. 50Ω microstrip line; 8. H-plane waveguide; 9. Waveguide groove; 10. Diaphragm; 11. Bifurcation waveguide; 12. AlN-based thin film resistor. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0031] It should be noted that the terms "comprising" or "may include" used in the various embodiments of this application indicate the presence of the claimed function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in the various embodiments of this application, the terms "comprising," "having," and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0032] It should be understood that terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] Figure 1 This is a schematic diagram of the rectangular waveguide 3-microstrip power divider provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the rectangular waveguide 3 microstrip power divider is divided into a mirror-symmetrical upper waveguide 1 and lower waveguide 2 along the center line of the wide side of the rectangular waveguide 3. A microstrip probe 5 is suspended in each of the upper waveguide 1 and lower waveguide 2 along the center line of the wide side of the rectangular waveguide 3. The microstrip probes 5 suspended in the upper waveguide 1 and lower waveguide 2 form a face-to-face double probe structure with the center line of the wide side of the rectangular waveguide 3 as the plane of symmetry.

[0034] Waveguide isolation structures are formed on the end faces of the two microstrip probes 5 to absorb the mutual coupling signals generated by the dual probe structure.

[0035] Specifically, a rectangular waveguide is a hollow metal tube with a rectangular cross-section used to transmit microwave signals (typically at frequencies above 1 GHz). It is one of the most basic and commonly used transmission line structures in microwave engineering.

[0036] Suspended microstrip probes 5 are installed inside the upper waveguide 1 and the lower waveguide 2, such as... Figure 2 As shown, the microstrip probe 5 is parallel to the centerline of the wide side of the rectangular waveguide 3, and is used to couple the signal in the rectangular waveguide 3. After impedance matching via the high-impedance transformation line 6, the signal can be efficiently transmitted to the 50Ω microstrip line 7. Since the upper waveguide 1 and the lower waveguide 2 have a mirror-symmetric structure, they can form a face-to-face microstrip dual-probe structure after being fixed together. When a microwave signal is input from the rectangular waveguide 3, it will be simultaneously coupled by the mirror-symmetrically arranged microstrip dual probes, forming two paths, thereby realizing the power distribution function of the microstrip of the rectangular waveguide 3.

[0037] If a microwave signal is input from either microstrip probe 5, it will be coupled by the other microstrip probe 5, which is its mirror image, thus creating crosstalk between the power dividers. To solve the crosstalk problem, this invention provides an H-plane waveguide 8, orthogonal to one end face of a microstrip probe 5, on the wide side of the rectangular waveguide 3. This H-plane waveguide collects and conducts the mutual coupling signals generated by the dual-probe structure. Since a flat rectangular waveguide is usually called an H-plane waveguide, its characteristic is that the electric field lines are perpendicular. Therefore, the narrow side of the H-plane waveguide 8 is parallel to the electric field lines of the mutual coupling signals generated by the dual-probe structure, thus effectively collecting the mutual coupling signals. Furthermore, since the H-plane waveguide 8 is orthogonal to the rectangular waveguide 3 during installation, the microwave signal transmitted in the rectangular waveguide 3 will not enter the H-plane waveguide 8, thus not affecting the normal power distribution function of the power divider.

[0038] To further address the mutual coupling signals generated by the dual-probe structure, T-shaped bifurcations are made on the end faces of the two H-plane waveguides 8 away from the microstrip probe 5, forming bifurcated waveguides 11 in the upper waveguide 1 and lower waveguide 2, respectively. This invention connects the T-shaped bifurcated waveguides 11 after the H-plane waveguides 8, splitting the signal into two paths for vertical transmission to the upper waveguide 1 and lower waveguide 2, respectively. Finally, an AlN-based thin-film resistor 12 is horizontally placed at the end of the bifurcated waveguides 11 to achieve final absorption of the mutual coupling signals. It is understood that the waveguide isolation structure proposed in this invention also improves the isolation of the microstrip power divider in the rectangular waveguide 3.

[0039] AlN-based thin-film resistors are resistive elements fabricated on aluminum nitride ceramic substrates using thin-film processes such as physical vapor deposition. The substrate can be aluminum nitride, and the resistive element is a very thin resistive film (typically tens to hundreds of nanometers). AlN-based thin-film resistors can be obtained using thin-film processes such as sputtering and evaporation. Their core value lies in combining the excellent properties of the AlN substrate with the precision characteristics of thin-film technology.

[0040] like Figure 3 As shown, within approximately 20% of the relative bandwidth centered at 34.5 GHz, the 3-port echo of the rectangular waveguide is below -20 dB, the transmission at the two microstrip line branches has an equal power distribution of -3 dB, and the echo is below -13 dB, with an isolation greater than 15 dB.

[0041] The present invention forms a waveguide isolation terminal consisting of an H-plane waveguide 8, a bifurcated waveguide 11, and an AlN-based thin-film resistor 12 on the end faces of two microstrip probes 5, thereby improving the isolation of the rectangular waveguide 3 microstrip power divider to more than 15dB within a 20% relative bandwidth. At the same time, the AlN-based thin-film resistor 12, whose bottom surface is in close contact with the metal cavity, absorbs the mutual coupling signal and forms an efficient heat dissipation path, which significantly improves the power processing capability.

[0042] Specifically, a waveguide groove 9 is formed in the rectangular waveguide 3 on the back of the microstrip probe 5; wherein the width of the waveguide groove 9 is the same as the width of the rectangular waveguide 3. Specifically, a diaphragm 10 is provided on the narrow sidewall of the H-plane waveguide 8.

[0043] In this embodiment, the waveguide groove 9 and the diaphragm 10 are used to change the distributed inductance in the circuit, thereby offsetting the waveguide microstrip coupling capacitance and adjusting the impedance matching of the rectangular waveguide 3 microstrip power divider.

[0044] Specifically, coaxial connector 4 is fixed to the back of the upper waveguide 1 and the lower waveguide 2 with screws. The rectangular waveguide 3 serves as the input terminal of the rectangular waveguide 3 microstrip power divider, and the coaxial connector 4 located between the upper waveguide 1 and the lower waveguide 2 serves as the output terminal of the rectangular waveguide 3 microstrip power divider. Specifically, the other side of the microstrip probe 5 is converted to a 50Ω microstrip line 7 via a high-impedance transformation line 6.

[0045] The coaxial connector 4 is mounted on the back of the cavity with screws, effectively connecting the outer conductor of the coaxial line to the cavity. The inner conductor of the coaxial line then passes through an opening in the cavity to enter its interior. Simultaneously, an opening is also made at the end of the 50Ω microstrip line 7 inside the cavity, allowing the inner conductor of the coaxial line to pass through as well. Soldering the inner conductor to the microstrip line establishes the electrical connection between the microstrip line and the inner conductor. This allows the RF signal located inside the cavity to be transmitted to the coaxial connector 4 outside the cavity, facilitating testing.

[0046] Specifically, in passive applications, the end of the 50Ω microstrip line 7 furthest from the microstrip probe 5 is opened to allow the inner conductor of the coaxial connector 4 to pass through the back of the cavity and be soldered; in active applications, the end of the 50Ω microstrip line 7 furthest from the microstrip probe 5 is bonded to the MIC via gold wire.

[0047] It should be noted that the welding and bonding methods described in this embodiment are already implemented in the existing technology, therefore, this embodiment will not elaborate on the working principle of this part. In both passive and active applications, this invention has good processability and MIC integration convenience, thus possessing the dual advantages of high power capacity and ease of active integration.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rectangular waveguide microstrip power divider, wherein the rectangular waveguide microstrip power divider is divided into a mirror-symmetrical upper waveguide and a lower waveguide along the centerline of the wide side of the rectangular waveguide, characterized in that, Along the centerline of the wide side of the rectangular waveguide, a microstrip probe is suspended on the upper waveguide and the lower waveguide respectively; wherein, the microstrip probes suspended on the upper waveguide and the lower waveguide form a face-to-face double probe structure with the centerline of the wide side of the rectangular waveguide as the plane of symmetry. Waveguide isolation structures are formed at the end faces of the two microstrip probes to absorb the mutual coupling signals generated by the dual-probe structure.

2. The rectangular waveguide microstrip power divider according to claim 1, characterized in that, The waveguide isolation structure includes an H-plane waveguide, a bifurcated waveguide, and an AlN-based thin-film resistor.

3. A rectangular waveguide microstrip power divider according to claim 2, characterized in that, An H-plane waveguide, orthogonal to one end face of a microstrip probe, is provided at the wide side of a rectangular waveguide to collect and conduct the mutual coupling signal generated by the dual-probe structure; wherein, the narrow side of the H-plane waveguide is parallel to the electric field lines of the mutual coupling signal generated by the dual-probe structure. T-shaped bifurcations are made on the end faces of the two H-plane waveguides away from the microstrip probe, respectively, to form the bifurcated waveguides in the upper and lower waveguides. The AlN-based thin-film resistor is horizontally disposed on the bifurcated waveguide to ultimately absorb the mutual coupling signal generated by the dual-probe structure.

4. A rectangular waveguide microstrip power divider according to claim 3, characterized in that, The H-plane waveguide is orthogonal to the rectangular waveguide.

5. A rectangular waveguide microstrip power divider according to claim 1, characterized in that, A waveguide groove is formed in the rectangular waveguide on the back of the microstrip probe; wherein the width of the waveguide groove is the same as the width of the rectangular waveguide.

6. A rectangular waveguide microstrip power divider according to claim 1, characterized in that, A diaphragm is provided on the narrow sidewall of the H-plane waveguide.

7. A rectangular waveguide microstrip power divider according to claim 1, characterized in that, Coaxial connectors are fixed to the back of the upper and lower waveguides respectively by screws. The rectangular waveguide serves as the input end of the rectangular waveguide microstrip power divider, and the coaxial connector located between the upper and lower waveguides serves as the output end of the rectangular waveguide microstrip power divider.

8. A rectangular waveguide microstrip power divider according to claim 7, characterized in that, The other side of the microstrip probe is converted into a 50Ω microstrip line via a high-impedance transformation line.

9. A rectangular waveguide microstrip power divider according to claim 8, characterized in that, In passive applications, the end of the 50Ω microstrip line away from the microstrip probe is opened to allow the inner conductor of the coaxial connector to pass through the back of the cavity and then be soldered. In active applications, the end of the 50Ω microstrip line furthest from the microstrip probe is bonded to the MIC via a gold wire.

10. A rectangular waveguide microstrip power divider according to claim 1, characterized in that, The microstrip probe is parallel to the center line of the wide side of the rectangular waveguide.

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