Ka-band waveguide-microstrip triplexer

Abstract

This application relates to the field of radio frequency microwave circuit technology and discloses a Ka-band waveguide-microstrip triode, comprising a first rectangular waveguide, a second rectangular waveguide, a first circuit fabricated on a dielectric substrate, and a pair of second circuits. This application utilizes the cooperation of the first rectangular waveguide, the second rectangular waveguide, the dielectric substrate, the first circuit, and the second circuit. A microstrip probe leads out a microstrip line from the wide side of the first rectangular waveguide, and two semi-circular circuits lead out microstrip lines from the two narrow sides of the first rectangular waveguide, respectively. It employs a hybrid circuit approach with rectangular waveguide input and microstrip line output, resulting in a compact structure. While achieving high isolation, low insertion loss, and excellent out-of-band suppression, it also facilitates integration with other circuits when expanding circuit functionality, meeting the usage requirements of a Ka-band waveguide-microstrip triode.

Description

Technical Field

[0001] This application relates to the field of radio frequency microwave circuit technology, specifically to a Ka-band waveguide-microstrip triode. Background Technology

[0002] A microwave tripod is a passive four-port network device primarily used to split wideband signals into multiple narrowband signals or to reverse-combine them. It is widely used in satellite communications, mobile base stations, radar, and electronic warfare systems. Its core function is to separate and synthesize multi-channel signals, enabling independent transmission of multiple signals while ensuring high isolation and wide stopband characteristics between channels.

[0003] The main technical specifications of a tripod include operating frequency range, passband insertion loss, out-of-band rejection, isolation between transmit and receive ports, voltage standing wave ratio (VSWR) of the ports, power capacity, and temperature stability.

[0004] Commonly used circuit structures for microwave triodes include low-temperature co-fired ceramic (LTCC) triodes, microstrip line triodes, and rectangular waveguide triodes. LTCC triodes utilize low-temperature co-fired ceramic technology, consisting of a single node and three filters, and feature low insertion loss, miniaturization, and high integration. Microstrip line triodes achieve frequency distribution through branch coupling or filter networks. Waveguide triodes are suitable for high-frequency, high-power applications, achieving signal distribution through waveguide branches and ferrite devices, offering low loss and high reliability. In practical applications, there are also instances where different transmission line structures are mixed in triode circuit design, such as microstrip line triodes fabricated using LTCC technology and waveguide-microstrip hybrid triodes. These types of triodes offer advantages such as more compact circuit design at higher frequency bands, such as millimeter-wave bands, and ease of integration with other circuits.

[0005] In related technologies, a circuit structure is constructed by placing a dielectric substrate at the cross-sectional position of a rectangular waveguide, using the rectangular waveguide as the signal input terminal, and fabricating a microstrip line on the dielectric substrate as the signal output terminal. However, it is not easy to ensure that the distance between the dielectric substrate and the short-circuit surface of the rectangular waveguide is the same size, so as to ensure that all three outputs of the duplexer have good transmission performance. Therefore, the duplexer circuit is mainly implemented by inserting two microstrip probes or two ring-shaped circuits in the rectangular waveguide. This results in the limited use of waveguide-microstrip-hybrid duplexers based on this circuit structure, which cannot meet the needs of some operating conditions. Summary of the Invention

[0006] This application provides a Ka-band waveguide-microstrip triode to solve or improve the problem that existing waveguide-microstrip-hybrid triodes are limited in use and cannot meet the needs of some operating conditions.

[0007] This invention provides a Ka-band waveguide-microstrip triode, comprising:

[0008] The first rectangular waveguide is used for inputting electromagnetic signals;

[0009] A dielectric substrate is attached to the bottom cross-section of the first rectangular waveguide;

[0010] A first circuit is disposed on the upper surface of the dielectric substrate. A microstrip probe is disposed at one end of the first circuit. The microstrip probe extends into the first rectangular waveguide and is located on a wide side of the first rectangular waveguide.

[0011] A pair of second circuits are disposed on the upper surface of the dielectric substrate. One end of the second circuit is provided with a semi-circular circuit. Both of the semi-circular circuits extend into the first rectangular waveguide, and the pair of semi-circular circuits are respectively located on the two narrow sides of the first rectangular waveguide.

[0012] In an optional embodiment, a second rectangular waveguide is further included, the second rectangular waveguide being short-circuited at its terminal and connected to the lower surface of the dielectric substrate, and the cross-sectional dimensions of the second rectangular waveguide are the same as those of the first rectangular waveguide.

[0013] In one alternative embodiment, two circular circuits are disposed on the lower surface of the dielectric substrate, and the two circular circuits are disposed corresponding to the terminal short-circuit of the second rectangular waveguide.

[0014] In one alternative embodiment, the microstrip probe is coaxially arranged with the line connecting the centers of the two wide sides of the bottom cross-section of the first rectangular waveguide.

[0015] In one alternative embodiment, the pair of semi-circular circuits on the dielectric substrate are located on both sides of the line connecting the centers of the two wide sides of the bottom cross-section of the first rectangular waveguide.

[0016] In one alternative embodiment, the first circuit further includes a first impedance matching circuit, a first bandpass filter, and a first standard 50-ohm output microstrip line connected in sequence, with one end of the first impedance matching circuit connected to the microstrip probe.

[0017] In one alternative embodiment, the second circuit further includes a second impedance matching circuit, a second bandpass filter, and a second standard 50-ohm output microstrip line connected in sequence, with one end of the second impedance matching circuit connected to the semi-circular circuit.

[0018] In one alternative embodiment, the straight segment of the semicircular circuit forming the semicircle has a break, so that the semicircular circuit forms two connection portions, and the second impedance matching circuit is connected to one of the connection portions located at the center of the narrow side of the first rectangular waveguide.

[0019] In one alternative embodiment, another of the connecting parts is connected to a grounding wire.

[0020] In an optional embodiment, the system further includes three opening slots extending from the first rectangular waveguide, one of which is formed on the wide side of the first rectangular waveguide, and the other two opening slots are formed on the two narrow sides of the first rectangular waveguide, respectively, and all three opening slots are in communication with the interior of the first rectangular waveguide.

[0021] The embodiments disclosed in this application provide a Ka-band waveguide-microstrip triode, which utilizes a first rectangular waveguide, a second rectangular waveguide, a dielectric substrate, a first circuit, and a second circuit in combination. A microstrip probe is respectively disposed on one wide side of the first rectangular waveguide, and semi-circular circuits are respectively disposed on the two narrow sides of the first rectangular waveguide. The microstrip probe leads out a microstrip line from the wide side of the first rectangular waveguide, and the two semi-circular circuits lead out microstrip lines from the two narrow sides of the first rectangular waveguide, respectively. It adopts a hybrid circuit method with rectangular waveguide input and microstrip line output, which has a compact structure. While achieving technical indicators such as high isolation, low insertion loss, and excellent out-of-band suppression, it is also easy to integrate with other circuits when expanding circuit functions, thus meeting the usage requirements of Ka-band waveguide-microstrip triodes. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a three-dimensional structural diagram of a Ka-band waveguide-microstrip triode according to an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the circuit on the upper surface of the dielectric substrate according to an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the circuit on the lower surface of the dielectric substrate according to an embodiment of this application;

[0026] Figure 4 The input return loss (S) of the tripod in this application embodiment11 ) and insertion loss (S 21 S 31 S 41 Simulation result diagram;

[0027] Figure 5 The isolation between the output ports of the tripod in this embodiment of the application is (S). 23 S 34 S 24 Simulation results diagram.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First rectangular waveguide; 2. Dielectric substrate;

[0030] 3. First circuit; 31. Microstrip probe; 32. First impedance matching circuit; 33. First bandpass filter; 34. First standard 50-ohm output microstrip line;

[0031] 4. Second circuit; 41. Semi-circular loop circuit; 42. Second impedance matching circuit; 43. Second bandpass filter; 44. Second standard 50-ohm output microstrip line; 45. Disconnection section; 46. Grounding strip;

[0032] 5. Second rectangular waveguide; 6. Circular circuit; 7. Opening slot; 8. Lower surface region; 9. Copper layer region of dielectric substrate. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments 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.

[0034] A microwave tripod is a passive four-port network device primarily used to split wideband signals into multiple narrowband signals or to reverse-combine them. It is widely used in satellite communications, mobile base stations, radar, and electronic warfare systems. Its core function is to separate and synthesize multi-channel signals, enabling independent transmission of multiple signals while ensuring high isolation and wide stopband characteristics between channels.

[0035] Commonly used circuit structures for microwave triodes include low-temperature co-fired ceramic (LTCC) triodes, microstrip line triodes, and rectangular waveguide triodes. In practical applications, there are also instances where different transmission line structures are mixed to design triode circuits, such as microstrip line triodes made using LTCC technology and waveguide-microstrip hybrid triodes. These types of triodes offer advantages such as more compact circuit design at higher frequency bands, such as millimeter wave bands, and ease of integration with other circuits.

[0036] In related technologies, a circuit structure is constructed by placing a dielectric substrate 2 at the cross-sectional position of a rectangular waveguide, using the rectangular waveguide as the signal input terminal, and fabricating a microstrip line on the dielectric substrate 2 as the signal output terminal. However, it is not easy to ensure that the distance between the dielectric substrate 2 and the short-circuit surface of the rectangular waveguide is the same size, so as to ensure that all three outputs of the duplexer have good transmission performance. Therefore, the duplexer circuit is mainly implemented by inserting two microstrip probes or two ring-shaped circuits in the rectangular waveguide. This results in the limited use of waveguide-microstrip-hybrid duplexers based on this circuit structure, which cannot meet the usage requirements of some applications.

[0037] The following is combined with Figures 1 to 5 This invention describes embodiments of the present application. The present invention provides a Ka-band waveguide-microstrip triode, comprising a first rectangular waveguide 1, a second rectangular waveguide 5, a dielectric substrate 2, a first circuit 3, and a pair of second circuits 4.

[0038] The first rectangular waveguide 1 is used to input electromagnetic signals. The length of the first rectangular waveguide 1 is arranged vertically. The two surfaces of the first rectangular waveguide 1 used for signal transmission are defined as the input surface and the output surface. Among the other four surfaces around the first rectangular waveguide 1, the surface with a relatively small area is defined as the narrow side and the surface with a relatively large area is defined as the wide side.

[0039] The dielectric substrate 2 is connected to the bottom cross-section of the first rectangular waveguide 1, i.e., the dielectric substrate 2 is connected to the output surface of the first rectangular waveguide 1. The first circuit 3 is disposed on the upper surface of the dielectric substrate 2. A microstrip probe 31 is disposed at one end of the first circuit 3. The microstrip probe 31 extends into the first rectangular waveguide 1 and is located on one wide side of the first rectangular waveguide 1. A pair of second circuits 4 are disposed on the upper surface of the dielectric substrate 2. A semi-circular circuit 41 is disposed at one end of the second circuit 4. Both semi-circular circuits 41 extend into the first rectangular waveguide 1, and the pair of semi-circular circuits 41 are respectively located on the two narrow sides of the first rectangular waveguide 1.

[0040] As can be seen from the above scheme, the present invention is ingeniously designed, compact in structure, and easy to implement and install in engineering. Utilizing the cooperation of a first rectangular waveguide 1, a second rectangular waveguide 5, a dielectric substrate 2, a first circuit 3, and a second circuit 4, a microstrip probe 31 is respectively set on one wide side of the first rectangular waveguide 1, and semi-circular circuits 41 are respectively set on the two narrow sides of the first rectangular waveguide 1. The microstrip probe 31 leads out a microstrip line from the wide side of the first rectangular waveguide 1, and the two semi-circular circuits 41 lead out microstrip lines from the two narrow sides of the first rectangular waveguide 1. This hybrid circuit approach, with rectangular waveguide input and microstrip line output, has a compact structure. While achieving high isolation, low insertion loss, and excellent out-of-band suppression, it also facilitates integration with other circuits when expanding circuit functionality, meeting the usage requirements of a Ka-band waveguide-microstrip triode.

[0041] like Figure 2 As shown, the microstrip probe 31 and the rectangular waveguide master mode TE 10 The electric field direction of the mode is consistent, and the annular surface of the semi-circular circuit 41 is aligned with the main mode TE of the rectangular waveguide. 10 The longitudinal magnetic field component of the module is perpendicular, and this setting ensures that the power of the input electromagnetic signal is coupled and output.

[0042] It should be noted that by changing the structural dimensions of the microstrip probe 31 and the semi-circular circuit 41 on the dielectric substrate 2, as well as their relative positions within the first rectangular waveguide 1, it is possible to achieve better transmission characteristics for the three output channels in their respective required transmission frequency bands. Furthermore, based on this circuit structure, other circuits can be further integrated on the dielectric substrate 2 to design and implement circuit components with more functions, enabling wider applications in microwave and millimeter-wave circuits and systems.

[0043] In one embodiment, a second rectangular waveguide 5 is further included. The second rectangular waveguide 5 is short-circuited at its terminal and connected to the lower surface of the dielectric substrate 2. The cross-sectional dimensions of the second rectangular waveguide 5 are the same as those of the first rectangular waveguide 1.

[0044] In this embodiment, as Figure 1 As shown, the width and narrow sides of the second rectangular waveguide 5 are the same as those of the first rectangular waveguide 1. The second rectangular waveguide 5 is used to be placed on the back side of the dielectric substrate 2. The waveguide port of the second rectangular waveguide 5 is precisely aligned with the waveguide port of the first rectangular waveguide 1. The first rectangular waveguide 1, the dielectric substrate 2, and the second rectangular waveguide 5 are tightly connected and assembled together.

[0045] like Figure 3 As shown, the middle region of the lower surface of the dielectric substrate 2 is the lower surface region 8 of the same size as the second rectangular waveguide 5, and the surrounding area is the copper cladding layer region 9 of the dielectric substrate.

[0046] In one embodiment, two circular circuits 6 are disposed within the lower surface region 8 of the dielectric substrate 2, and the two circular circuits 6 are correspondingly disposed with respect to the terminal short-circuit surface of the second rectangular waveguide 5. That is, the two circular circuits 6 and the terminal short-circuit second rectangular waveguide 5 are both part of the circuit composition structure for implementing a three-way excitation coupled output signal device in the first rectangular waveguide 1. By uniformly optimizing the distance between the dielectric substrate 2 and the short-circuit surface of the second rectangular waveguide 5, as well as the radius and relative positions of the circular circuits 6, optimal output transmission performance for three different frequency bands can be obtained.

[0047] Understandably, the specific shape and number of circuits disposed on the lower surface of the dielectric substrate 2 can be adaptively adjusted according to actual needs, and each circuit is preferably disposed at intervals.

[0048] In one embodiment, such as Figure 2 As shown, the microstrip probe 31 is coaxially arranged with the line connecting the centers of the two wide sides of the bottom cross section of the first rectangular waveguide 1, so that the microstrip probe 31 of the first circuit 3 is inserted vertically into the wide side from the center of the wide side of the first rectangular waveguide 1.

[0049] In one embodiment, such as Figure 2 As shown, a pair of semi-circular circuits 41 on the dielectric substrate 2 are located on both sides of the line connecting the centers of the two wide sides of the bottom cross section of the first rectangular waveguide 1, so that the semi-circular circuits 41 of the pair of second circuits 4 are vertically inserted into the narrow side of the first rectangular waveguide 1 from the center of the narrow side, thereby realizing the output of the excitation coupled signal power in the first rectangular waveguide 1.

[0050] In one embodiment, the first circuit 3 further includes a first impedance matching circuit 32, a first bandpass filter 33, and a first standard 50-ohm output microstrip line 34 connected in sequence, with one end of the first impedance matching circuit 32 connected to the microstrip probe 31.

[0051] In this embodiment, as Figure 2 As shown, one end of the first impedance matching circuit 32 is connected to the microstrip probe 31, the other end of the first impedance matching circuit 32 is connected to the first bandpass filter 33, and the other end of the first bandpass filter 33 is connected to the first standard 50-ohm output microstrip line 34.

[0052] In one embodiment, the second circuit 4 further includes a second impedance matching circuit 42, a second bandpass filter 43, and a second standard 50-ohm output microstrip line 44 connected in sequence, with one end of the second impedance matching circuit 42 connected to the semi-circular circuit 41.

[0053] In this embodiment, as Figure 2As shown, one end of the second impedance matching circuit 42 is connected to the semi-circular circuit 41, the other end of the second impedance matching circuit 42 is connected to the second bandpass filter 43, and the other end of the second bandpass filter 43 is connected to the second standard 50-ohm output microstrip line 44.

[0054] In one embodiment, such as Figure 2 As shown, the straight segment of the semicircular circuit 41 that forms the semicircle has a break 45, so that the semicircular circuit 41 forms two connection points. One of the break points is located at the center of the narrow side of the first rectangular waveguide 1 and is directly connected to the second impedance matching circuit 42, the second bandpass filter 43, and the second standard 50-ohm output microstrip line 44 at the rear end for output. The other break point is grounded by connecting to the grounding strip line 46.

[0055] In one embodiment, such as Figure 1 As shown, it also includes three opening slots 7 extending from the first rectangular waveguide 1. One of the opening slots 7 is formed on the wide side of the first rectangular waveguide 1, and the other two opening slots 7 are formed on the two narrow sides of the first rectangular waveguide 1, respectively. All three opening slots 7 are connected to the interior of the first rectangular waveguide 1.

[0056] In one specific embodiment, the circuit structure of a Ka-band waveguide-microstrip triode is mainly completed by circuits placed on the upper and lower surfaces of a dielectric substrate 2 on a rectangular waveguide cross section.

[0057] In some embodiments, the dielectric substrate 2 is made of Rogers RT / duroid 5880 material with a thickness of 0.254 mm. A microstrip probe 31 and a pair of semi-circular ring circuits 41 are fabricated on the dielectric substrate 2 located inside the rectangular waveguide, enabling outward coupling of the output signal via one electrical excitation and two magnetic excitations. The microstrip probe 31 is located at the center of the wide side of the first rectangular waveguide 1, with a strip width of 0.315 mm and a length of 2.135 mm within the first rectangular waveguide 1. Among the two semi-circular ring circuits 41 located on the narrow sides of the first rectangular waveguide 1, the left semi-circular ring circuit 41 has an inner radius of 0.806 mm and a ring width of 0.391 mm. The metal strip connecting the breakpoint of the semi-circular ring circuit 41 and leading to the adjacent narrow side wall of the waveguide has a width of 0.204 mm and a length of 1.093 mm. The inner radius of the semi-circular circuit 41 located on the right is 0.802 mm, the loop width is 0.393 mm, and the metal strip connecting the break point of the semi-circular circuit 41 and leading to the narrow sidewall of the waveguide has a width of 0.206 mm and a length of 1.961 mm.

[0058] The output signals from one microstrip probe 31 and two semi-circular circuits 41, which are respectively led out to the wide wall on one side and the narrow walls on both sides of the first rectangular waveguide 1, are cascaded with the impedance matching circuits on the side wall and the dielectric substrate 2 outside the side wall of the first rectangular waveguide 1. Then, they are cascaded with three hairpin bandpass filters with center frequencies f1 of 29 GHz, f2 of 32 GHz and f3 of 35 GHz. Together with the two metal circular circuits with radii of 0.38 mm and 0.41 mm on the back of the dielectric substrate 2 inside the first rectangular waveguide 1, and the structure with a distance of 1.547 mm between the back of the dielectric substrate 2 and the short surface of the second rectangular waveguide 5, they finally form a tripartite circuit with a rectangular waveguide as input and three standard microstrip lines as outputs.

[0059] like Figure 4 As shown, the curves represent the insertion loss and return loss of the two channels of the Ka-band triode in this embodiment. Figure 4 It can be seen that the three output frequency bands of the tripod are in the frequency ranges of 28.5-29.3GHz, 31.6-32.5GHz and 34.6-35.6GHz respectively. The insertion loss of the output port in the passband is less than 0.5dB, and the input return loss in the passband is better than -20dB.

[0060] like Figure 5 As shown, this is the curve of the isolation of the Ka-band triode in this embodiment. Figure 5 It can be seen that the isolation is better than -30dB throughout the entire Ka band, and exceeds -50dB at the highest point.

[0061] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A Ka-band waveguide-microstrip triode, characterized in that, include: The first rectangular waveguide (1) is used to input electromagnetic signals; The dielectric substrate (2) is connected to the bottom cross-section of the first rectangular waveguide (1); A first circuit (3) is disposed on the upper surface of the dielectric substrate (2). A microstrip probe (31) is disposed at one end of the first circuit (3). The microstrip probe (31) extends into the first rectangular waveguide (1) and is located on a wide side of the first rectangular waveguide (1). A pair of second circuits (4) are disposed on the upper surface of the dielectric substrate (2). One end of the second circuit (4) is provided with a semi-circular circuit (41). Both of the semi-circular circuits (41) extend into the first rectangular waveguide (1), and the pair of semi-circular circuits (41) are respectively located on the two narrow sides of the first rectangular waveguide (1). The second circuit (4) also includes a second impedance matching circuit (42), a second bandpass filter (43), and a second standard 50-ohm output microstrip line (44) connected in sequence. One end of the second impedance matching circuit (42) is connected to the semi-circular circuit (41). The semi-circular circuit (41) has a break (45) in the straight segment of the semi-circular circuit (41) so that the semi-circular circuit (41) forms two connection parts. The second impedance matching circuit (42) is connected to one of the connection parts located at the center of the narrow side of the first rectangular waveguide (1). The other connection part is connected to a grounding strip line (46). The microstrip probe (31) leads out a microstrip line from the wide side of the first rectangular waveguide (1), and the two semi-circular circuits (41) lead out microstrip lines from the two narrow sides of the first rectangular waveguide (1) respectively. A hybrid circuit method with rectangular waveguide input and microstrip line output is adopted. It also includes a second rectangular waveguide (5), the second rectangular waveguide (5) is short-circuited at its end and connected to the lower surface of the dielectric substrate (2), and the cross-sectional dimensions of the second rectangular waveguide (5) are the same as those of the first rectangular waveguide (1); Two circular circuits (6) are provided on the lower surface of the dielectric substrate (2), and the two circular circuits (6) are provided corresponding to the terminal short surface of the second rectangular waveguide (5).

2. The Ka-band waveguide-microstrip triode according to claim 1, characterized in that, The microstrip probe (31) is coaxially arranged with the center line connecting the two wide sides of the bottom cross section of the first rectangular waveguide (1).

3. The Ka-band waveguide-microstrip triode according to claim 1, characterized in that, The pair of semi-circular circuits (41) on the dielectric substrate (2) are located on both sides of the line connecting the center of the two wide sides of the bottom cross section of the first rectangular waveguide (1).

4. The Ka-band waveguide-microstrip triode according to claim 1, characterized in that, The first circuit (3) further includes a first impedance matching circuit (32), a first bandpass filter (33) and a first standard 50-ohm output microstrip line (34) connected in sequence, with one end of the first impedance matching circuit (32) connected to the microstrip probe (31).

5. The Ka-band waveguide-microstrip triode according to any one of claims 1-4, characterized in that, It also includes three opening slots (7) extending from the first rectangular waveguide (1), one of which is formed on the wide side of the first rectangular waveguide (1), and the other two are formed on the two narrow sides of the first rectangular waveguide (1), and all three opening slots (7) are connected to the interior of the first rectangular waveguide (1).

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