A rectangular waveguide microstrip power divider

Abstract

The application discloses a rectangular waveguide microstrip power divider, and relates to the microwave device field, and solves the problem of insufficient power processing capacity in the prior art.The technical scheme is 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; the microstrip probes suspended on the upper waveguide body and the lower waveguide body form a double-probe structure in a face-to-face mode with the center line of the wide side of the rectangular waveguide as a symmetry plane; and a waveguide isolation structure is formed on the end face of the two microstrip probes, so as to absorb the mutual coupling signals generated by the double-probe structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave devices, and more particularly, to a rectangular waveguide microstrip power divider. BACKGROUND

[0002] Microwave is electromagnetic wave with wavelength between 1 m and 1 mm, corresponding to frequency between 300 MHz and 300 GHz. Microwave is the main carrier of wireless information transmission today, and is widely used in communication, radar, electronic countermeasures, telemetry and remote sensing, industrial production and other fields. Power divider is one of the most widely used devices in microwave circuits, which mainly functions to divide microwave signals into two or more coherent signals with different power, and also can inversely combine multiple microwave signals with different power into one output. During the whole process, the frequency of the microwave signal does not change, only the amplitude and phase change.

[0003] There are various circuit forms of power dividers, including Wilkinson bridge, Lange bridge, branch line bridge, T-junction and magic T structure. According to application requirements, various microwave transmission lines such as microstrip line, stripline, coaxial line, coplanar waveguide, substrate integrated waveguide and rectangular waveguide can be used independently or in combination. Among them, the rectangular waveguide-microstrip hybrid power divider has unique advantages: the rectangular waveguide as the main port can carry high power, while the microstrip branch port is convenient for integrating semiconductor devices. This type of power divider usually symmetrically arranges multiple microstrip probes inside the waveguide to simultaneously realize signal transition and power distribution functions. Due to the integrated transition and power distribution design, the waveguide-microstrip power divider has the significant advantages of compact structure and small insertion loss.

[0004] According to the different positions of the microstrip probes inserted into the waveguide, various structural forms of waveguide-microstrip power dividers can be formed. One typical structure is to symmetrically insert two microstrip probes on the same wide side of the rectangular waveguide, and the two probes are mirror symmetric with the center of the waveguide wide side as the mirror symmetric surface, forming a face-to-face double probe structure. This structure couples the microwave signals in the rectangular waveguide and distributes them to two microstrip lines with equal amplitude and phase. However, this conventional structure has obvious limitations: although the power distribution function is realized, due to the lack of isolation circuit design, the isolation between the two microstrip probes can only theoretically reach 6 dB. This performance defect makes it difficult to meet the needs of phased array feeder network, balanced mixer and high-power synthesis system and other application scenarios.

[0005] At present, there are several schemes to improve the isolation of rectangular waveguide-microstrip double-probe power divider. For example, Chinese patent CN113258244A proposes a rectangular waveguide microstrip 0° phase difference high isolation wideband power divider. This scheme sets a non-contact thin film resistor in the rectangular waveguide perpendicular to the end face of the microstrip probe, uses the thin film resistor to absorb the vertical component of the coupling electric field between the two microstrip probes, and thus improves the isolation performance. However, this scheme has two main technical defects: 1) the isolation circuit adopts a suspended structure, lacks an effective heat conduction path, and thus the power handling capability is limited; 2) the non-contact precision of the resistor is very high, which makes the structure difficult to implement and difficult to mass produce. SUMMARY

[0006] The purpose of the present application is to provide a rectangular waveguide microstrip power divider, which solves the problem of insufficient power handling capability in the prior art.

[0007] The above technical purpose of the present application is achieved by the following technical scheme:

[0008] The present application provides a rectangular waveguide microstrip power divider, which is divided into mirror-symmetric upper waveguide body and lower waveguide body along the center line of the wide side of the rectangular waveguide, and a microstrip probe is suspended on each of the upper waveguide body and the lower waveguide body along the direction of the center line of the wide side of the rectangular waveguide; wherein the microstrip probes suspended on the upper waveguide body and the lower waveguide body form a double-probe structure in face-to-face manner with the center line of the wide side of the rectangular waveguide as the symmetry plane.

[0009] A waveguide isolation structure is formed on the end face of the two microstrip probes to absorb the mutual coupling signals generated by the double-probe structure.

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

[0011] In an implementation scheme, the H-plane waveguide orthogonal to one side end face of the microstrip probe is arranged at the wide side of the rectangular waveguide to collect and conduct the mutual coupling signals generated by the double-probe structure; wherein the narrow side of the H-plane waveguide is parallel to the electric field force line of the mutual coupling signals generated by the double-probe structure.

[0012] The two H-plane waveguides are respectively T-shaped bifurcated at the side end face away from the microstrip probe to form the bifurcated waveguide in the upper waveguide body and the lower waveguide body, respectively.

[0013] The AlN-based thin film resistor is arranged horizontally on the bifurcated waveguide to finally absorb the mutual coupling signals generated by the double-probe structure.

[0014] In an implementation scheme, the H-plane waveguide is orthogonal to the rectangular waveguide.

[0015] In an implementation, a waveguide groove is formed in the back of the rectangular waveguide of the microstrip probe; wherein the width of the waveguide groove is consistent with the width of the rectangular waveguide.

[0016] In an implementation, a diaphragm is arranged on the narrow edge wall surface of the H-plane waveguide.

[0017] In an implementation, coaxial connectors are fixed on the back of the upper waveguide body and the lower waveguide body by screws, the rectangular waveguide is used as the input end of the rectangular waveguide microstrip power divider, and the coaxial connectors of the upper waveguide body and the lower waveguide body are used as the output end of the rectangular waveguide microstrip power divider.

[0018] In an implementation, the other side of the microstrip probe is converted into a 50Ω microstrip line through a high-impedance conversion line.

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

[0020] In an active application, the end of the 50Ω microstrip line away from the microstrip probe is bonded with the MIC through a gold wire.

[0021] In an implementation, the microstrip probe and the center line of the wide edge of the rectangular waveguide are parallel to each other.

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

[0023] The present application forms an H-plane waveguide, a bifurcated waveguide and an AlN-based thin film resistor on the end surface of two microstrip probes to form a waveguide isolation terminal, so that the isolation of the rectangular waveguide microstrip power divider within a 20% relative bandwidth is improved to more than 15dB; at the same time, the AlN-based thin film resistor with the bottom surface in close contact with the metal cavity absorbs the mutual coupling signal to form an efficient heat dissipation path, thereby significantly improving the power handling capability; in addition, the structure of the rectangular waveguide microstrip power divider provided by the present application is simple in processing and assembly process, and can realize batch production. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0025] Figure 1 The structure of the rectangular waveguide microstrip power divider provided by the present application is shown in the structure diagram;

[0026] Figure 2 The front view of the rectangular waveguide microstrip power divider provided by the present application is shown in the structure diagram;

[0027] Figure 3A parameter simulation diagram of the rectangular waveguide microstrip power divider provided by the embodiment of the present application.

[0028] Reference signs and drawing description:

[0029] 1, upper waveguide body; 2, lower waveguide body; 3, rectangular waveguide; 4, coaxial connector; 5, microstrip probe; 6, high-impedance transition line; 7, 50Ω microstrip line; 8, H-plane waveguide; 9, waveguide groove; 10, diaphragm; 11, bifurcated waveguide; 12, AlN-based thin-film resistor. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be given to the present application in combination with embodiments and drawings, and the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and not to limit the present application.

[0031] It should be noted that the term "include" or "may include" used in various embodiments of the present application indicates the existence of the claimed function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their synonyms only mean to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing, and should not be understood as first excluding the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing, or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing.

[0032] It should be understood that terms such as "first", "second" are only used for description purposes, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0033] Figure 1 A structure schematic diagram of the rectangular waveguide 3 microstrip power divider provided by the embodiment of the present application is shown in Figure 1 The rectangular waveguide 3 microstrip power divider is divided into mirror-symmetrical upper waveguide body 1 and lower waveguide body 2 along the center line of the wide side of the rectangular waveguide 3, and a microstrip probe 5 is suspended in each of the upper waveguide body 1 and the lower waveguide body 2 along the direction of the center line of the wide side of the rectangular waveguide 3; wherein the microstrip probes 5 suspended by the upper waveguide body 1 and the lower waveguide body 2 form a double-probe structure in face-to-face manner 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 resistor refers to a resistor element made on an aluminum nitride ceramic substrate through a thin film process such as physical vapor deposition. The substrate can be aluminum nitride, and the resistor body is a very thin (usually tens of nanometers to hundreds of nanometers) resistor film. AlN-based thin film resistor can be obtained by using sputtering, evaporation and other thin film processes. Its core value lies in the combination of the excellent performance of the AlN substrate and the precision characteristics of the thin film technology.

[0040] As shown in Figure 3 In a relative bandwidth of about 20% with 34.5GHz as the center frequency, the return loss of the rectangular waveguide 3 port is below -20dB, the transmission of the two microstrip line branches is equal to -3dB equal power distribution, and the return loss is below -13dB, and the isolation is higher than 15dB.

[0041] The present application forms an H-plane waveguide 8, a bifurcated waveguide 11 and an AlN-based thin film resistor 12 together to form a waveguide isolation terminal at the end face of the two microstrip probes 5, so that the isolation of the rectangular waveguide 3 microstrip power divider in the relative bandwidth of 20% is improved to more than 15dB; at the same time, the AlN-based thin film resistor 12 with the bottom surface closely contacting the metal cavity absorbs the mutual coupling signal and forms a high-efficiency heat dissipation path, which significantly improves the power handling capability.

[0042] Specifically, a waveguide groove 9 is formed in the rectangular waveguide 3 at the back of the microstrip probe 5; wherein the width of the waveguide groove 9 is consistent with the width of the rectangular waveguide 3. Specifically, the narrow edge wall surface of the H-plane waveguide 8 is provided with a diaphragm 10.

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

[0044] Specifically, the coaxial connector 4 is fixed on the back of the upper waveguide body 1 and the lower waveguide body 2 by screws, the rectangular waveguide 3 serves as the input end of the rectangular waveguide 3 microstrip power divider, and the coaxial connector 4 of the upper waveguide body 1 and the lower waveguide body 2 serves as the output end of the rectangular waveguide 3 microstrip power divider. Specifically, the other side of the microstrip probe 5 is converted into a 50Ω microstrip line 7 through a high-impedance conversion line 6.

[0045] The coaxial connector 4 is installed on the back of the cavity by screws, which is equivalent to connecting the outer conductor of the coaxial line with the cavity. The inner conductor of the coaxial line passes through the hole in the cavity and enters the inside of the cavity. At the same time, the terminal of the 50Ω microstrip line 7 in the cavity is also opened, so that the coaxial inner conductor can also pass through the microstrip line. The coaxial inner conductor and the microstrip line are welded together, which realizes the electrical connection of the microstrip line and the coaxial inner conductor. Thus, the radio frequency signal located in the cavity can be transmitted to the coaxial connector 4 outside the cavity, which is convenient for testing.

[0046] Specifically, in passive applications, the 50Ω microstrip line 7 is soldered to the inner conductor of the coaxial connector 4 after the inner conductor is passed through the back of the cavity from the hole at the end of the microstrip probe 5; in active applications, the 50Ω microstrip line 7 is bonded to the MIC through a gold wire at the end away from the microstrip probe 5.

[0047] It should be noted that the soldering and bonding methods described in the embodiments are already implemented in the prior art, so the embodiments do not make redundant elaboration on the working principles of this part. In the provided passive and active applications, the application has good processability and MIC integration convenience, thus having the dual advantages of high power capacity and easy active integration.

[0048] The above detailed description of the specific embodiments has further detailed the purposes, technical solutions and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A rectangular waveguide microstrip power divider, which is divided into an upper waveguide body and a lower waveguide body that are mirror-symmetric to each other along the center line of the wide side of the rectangular waveguide, characterized in that, Two microstrip probes are suspended along the center line of the wide side of the rectangular waveguide, one on the upper waveguide and the other on the lower waveguide; wherein the microstrip probes suspended on the upper waveguide and the lower waveguide form a double-probe structure with the center line of the wide side of the rectangular waveguide as the symmetry plane; Waveguide isolation structures are formed on the end faces of the two microstrip probes to absorb the mutual coupling signals generated by the double-probe structure; wherein the waveguide isolation structures include H-plane waveguides, bifurcated waveguides and AlN-based thin film resistors; The H-plane waveguides are arranged orthogonally to the side end faces of the microstrip probes at the wide side of the rectangular waveguide to collect and conduct the mutual coupling signals generated by the double-probe structure; wherein the narrow side of the H-plane waveguide is parallel to the electric field force line of the mutual coupling signals generated by the double-probe structure; The two H-plane waveguides are respectively T-shaped bifurcated at the side end faces away from the microstrip probes to form the bifurcated waveguides in the upper waveguide and the lower waveguide respectively; The AlN-based thin film resistors are arranged horizontally on the bifurcated waveguides to finally absorb the mutual coupling signals generated by the double-probe structure; The H-plane waveguides are orthogonal to the rectangular waveguide.

2. The rectangular waveguide microstrip power divider of claim 1, wherein, A waveguide groove is formed in the rectangular waveguide at the back of the microstrip probe; wherein the width of the waveguide groove is consistent with the width of the rectangular waveguide.

3. The rectangular waveguide microstrip power divider of claim 1, wherein, A diaphragm is arranged on the narrow side wall of the H-plane waveguide.

4. The rectangular waveguide microstrip power divider of claim 1, wherein, Coaxial connectors are fixed to the back of the upper waveguide and the lower waveguide by screws, the rectangular waveguide serves as the input end of the rectangular waveguide microstrip power divider, and the coaxial connectors on the upper waveguide and the lower waveguide serve as the output end of the rectangular waveguide microstrip power divider.

5. The rectangular waveguide microstrip power divider of claim 4, wherein, The other side of the microstrip probe is converted into a 50Ω microstrip line through a high-impedance transition line.

6. The rectangular waveguide microstrip power divider of claim 5, wherein, In passive applications, the end of the 50Ω microstrip line away from the microstrip probe is perforated for the inner conductor of the coaxial connector to pass through the back of the cavity and then welded; In active applications, the end of the 50Ω microstrip line away from the microstrip probe is bonded with the MIC through a gold wire.

7. The rectangular waveguide microstrip power divider of claim 1, wherein, The microstrip probe is parallel to the center line of the wide side of the rectangular waveguide.

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