Compact broadband four-path strip line-waveguide power synthesis device

Abstract

The invention discloses a compact broadband four-path strip line-waveguide power synthesis device which comprises a standard waveguide unit, two PCB units arranged in a mirror symmetry mode and two metal wedge units arranged in a symmetrical mode. The standard waveguide unit comprises a standard waveguide cavity, a metal cover plate formed by integrally extending the wide side wall of the waveguide cavity, and a flange plate; each PCB unit comprises a strip line input section and a microstrip line probe section which are connected in sequence, and the microstrip line probe section extends into the waveguide cavity. The base part of each metal wedge unit is fixedly connected with the short circuit wall of the waveguide cavity, and the tip of the widest part of each metal wedge unit is welded with the tail end of the copper conduction band of the corresponding microstrip line probe section; the two sides of the base part of the metal wedge unit are provided with unfilled corners, and the unfilled corners correspond to a transition area from the strip line input section to the microstrip line probe section in the PCB unit and are used for achieving impedance matching and smooth transition. The microstrip line probe in the waveguide cavity and the bimetal wedge matching structure are used, power synthesis and mode conversion from the four strip lines to the waveguide are achieved, and the four-way strip line waveguide has the advantages of being compact in structure, easy and convenient to machine and wide in bandwidth.

Description

Technical Field

[0001] This invention relates to the field of radio frequency microwaves, and more specifically to a compact broadband four-way stripline-waveguide power combining device. Background Technology

[0002] Waveguides offer advantages such as high power handling capacity and low insertion loss in microwave transmission lines, enabling long-distance transmission of high-power microwave signals. Since the output power of a single component is relatively limited, it is generally necessary to combine the output power of multiple components to obtain higher power. Considering that the microwave circuitry and output ports within the components typically utilize microstrip lines or striplines, a combined synthesizer design is generally employed to facilitate integration with the components and reduce costs. The synthesizer's pre-stage uses a stripline synthesizer, and the final stage converts the stripline into a waveguide form. The final power is then combined and output through a high-power waveguide magic T.

[0003] When microwaves are transmitted through a two-conductor transmission line such as a stripline, the electromagnetic field distribution is TEM mode; while the dominant mode in a rectangular waveguide is TE. 10 The microstrip probe is inserted into the waveguide wall as a probe. Through certain design, it can excite an electromagnetic field within the waveguide, thus achieving microstrip-waveguide mode conversion. When microwaves inserted into the waveguide are transmitted through a two-conductor transmission line such as a stripline, the electromagnetic field distribution is in TEM mode. When there is more than one rectangular wave microstrip probe, multiple microwave energies can be spatially synthesized simultaneously within the waveguide cavity, achieving a broadband response. This still requires the use of waveguide T-junctions and waveguide stepped impedance transformation, resulting in a larger volume, but the fabrication is more compact and simpler compared to the Magic T structure. Because TE... 10 The electromagnetic field distribution is symmetrical about the centerline of the wide side of the waveguide, so implementing two inputs is quite common. Dual microstrip lines connected to a cavity form a ridge waveguide with double ridges. The ridges protrude from the waveguide cavity and gradually change impedance to achieve a large bandwidth. Increasing to four inputs is more complex. Summary of the Invention

[0004] The purpose of this invention is to propose a compact broadband four-way stripline-waveguide power combining device to achieve relatively compact high-power four-way power combining, simplify the structure, and reduce costs.

[0005] The technical solution for achieving the objective of this invention is: a compact broadband four-way stripline-waveguide power combining device, comprising a standard waveguide unit, two metal wedge units, and two PCB board units, wherein:

[0006] The standard waveguide unit includes a standard waveguide cavity, a metal cover plate, and a flange, wherein the metal cover plate is integrally formed by extending the wide sidewall of the waveguide cavity, and a flange is provided at the other end.

[0007] The two PCB board units have three copper clad layers and two dielectric substrate layers. The outermost two copper clad layers serve as a ground plane, and the middle copper clad layer is printed as two copper conductive strips. The two PCB board units are mirror-symmetrically arranged on the upper and lower wide sides of the standard waveguide cavity, closely attached to the inner wall of the waveguide. Each PCB board unit includes a stripline input segment and a microstrip line probe segment, wherein the stripline input segment and the microstrip line probe segment are connected in sequence. The microstrip line probe segment does not have an outer ground plane, exposes the copper conductive strip, and extends into the interior of the standard waveguide cavity.

[0008] The two metal wedge units are identical in structure and symmetrical vertically. They are symmetrically positioned within a standard waveguide cavity, with the upper and lower edges of the wedges flush with the copper conductors of the PCB unit. The side profile of the wedges gradually changes exponentially along the waveguide propagation direction, and the wedge tips horizontally cut the TE waveguide within the waveguide. 10 The vertical electric field in the mode forms a double conductor gradient structure with the inner wall of the standard waveguide cavity, guiding two microwave signals with equal amplitude and opposite direction from the upper and lower PCB board units to complete spatial synthesis in the waveguide cavity. The impedance of the double conductor structure conforms to the exponential curve function and has a smooth gradient, satisfying the principle of small microwave reflection and realizing impedance matching and mode matching under large bandwidth. The base of the wedge is fixedly connected to the short-circuit wall of the standard waveguide cavity, and its widest tip is electrically connected to the copper conductor end of the corresponding microstrip probe segment above and below.

[0009] The metal wedge unit has notched corners on both sides of its base. These notched corners correspond to the transition area between the stripline input segment and the microstrip probe segment of the PCB board unit. This is used to reduce the parasitic capacitance effect between the wedge and the probe conductor, achieve impedance matching, ensure the conversion between the TEM mode of the stripline and the quasi-TEM mode of the microstrip line, and suppress the generation of higher-order modes.

[0010] Furthermore, in the standard waveguide unit, the standard waveguide cavity adopts a rectangular waveguide, one end of which is an open end and connected to a flange, and the other end is a short-circuit end and forms a short-circuit wall;

[0011] On the upper and lower sides of the short-circuit wall, close to the inner wall of the wide side of the waveguide, a first slot is provided. The first slot extends outward along the wide side wall of the waveguide and is integrally connected with the metal cover plate.

[0012] Two second slots are provided on the wide side of the waveguide cavity end face opposite to the PCB board unit, for the microstrip line probe segment of the PCB board unit to extend into the standard waveguide cavity.

[0013] Furthermore, the stripline input segment of the PCB board unit is electrically contacted and fixed to the metal cover plate through the metal layers on its upper and lower surfaces.

[0014] Furthermore, the PCB board unit is fixed to the metal cover plate and the standard waveguide cavity wall by means of gluing or by connecting with bolts through screw holes.

[0015] Furthermore, the metal wedge unit is fixed to the short-circuit wall of the standard waveguide cavity by bolts.

[0016] Furthermore, the tip of the widest part of the metal wedge unit is electrically connected to the conductive strip of the microstrip probe segment by welding.

[0017] Furthermore, the length of the standard waveguide cavity is shorter than that of the metal wedge unit.

[0018] Furthermore, the flange adopts a standard flange structure and is fixedly connected by bolts.

[0019] Furthermore, the device is configured to be integrated with the transmitting assembly, wherein the transmitting assembly housing, PCB board unit and metal cover are respectively provided with screw holes, and are fixed to each other by bolts.

[0020] Furthermore, the assembly process is as follows:

[0021] First, complete the fixation of the PCB board unit on the standard waveguide unit and the bonding between the copper-clad metal layer and the metal cover plate;

[0022] Secondly, the metal wedge unit is fixed to the short-circuit wall of the standard waveguide cavity;

[0023] Finally, a soldering iron is inserted through the open end face of the standard waveguide unit with a flange to solder the tip of the metal wedge unit to the copper conductor end of the microstrip probe segment.

[0024] Compared with the prior art, the significant advantages of this invention are:

[0025] (1) The bimetallic wedge structure can support broadband impedance conversion and power synthesis of 4 striplines to waveguides, with a relative bandwidth of more than 30%. Compared with the traditional double-sided double-ridge waveguide structure, it omits the two half-height waveguides and transition structure stacked on the wide side, reducing volume and cost.

[0026] (2) By using the notched base design of the metal wedge, the reliable fixation and maintenance of the metal wedge unit can be ensured without affecting the electrical performance and while supporting a compact transition from stripline to microstrip probe.

[0027] (3) The input port adopts a stripline design, which facilitates the integration of high-power transmitting components / printed board microwave synthesis network. The output port adopts a flange connection, which facilitates connection with waveguide feeder and makes installation and maintenance convenient. Attached Figure Description

[0028] Figure 1 This is a front view of a compact broadband four-way stripline-waveguide power combining device.

[0029] Figure 2 Rear view of a compact broadband four-way stripline-waveguide power combining device.

[0030] Figure 3 This is a PCB board unit structure diagram of a compact broadband four-way stripline-waveguide power combining device.

[0031] Figure 4 The total voltage standing wave ratio of a compact broadband four-channel stripline-waveguide power combiner.

[0032] Figure 5 The amplitude response of the four stripline ports of a compact broadband four-way stripline-waveguide power combining device.

[0033] Figure 6 The phase response of the four stripline ports of a compact broadband four-way stripline-waveguide power combining device. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] A compact broadband four-way stripline-waveguide power combining device includes a standard waveguide unit 1, two metal wedge units 2, and two PCB board units 3, wherein:

[0036] The standard waveguide unit 1 includes a standard waveguide cavity 5, a metal cover plate 4, and a flange 6. The waveguide cavity 5 adopts a standard BJ32 waveguide, the metal cover plate 4 is integrally formed by the wide sidewall of the waveguide, and the flange 6 is provided at the other end.

[0037] The two PCB board units 3 are made of 1.524 mm thick board material with a dielectric constant of 3.55 and a copper thickness of 2 ounces. They have three copper layers and two dielectric substrate layers. The outermost two copper layers serve as the ground plane, and the middle copper layer is printed as two copper conductive strips. The two PCB board units 3 are mirror-symmetrically arranged on the upper and lower wide sides of the standard waveguide cavity 5 and are close to the inner wall of the waveguide. Each PCB board unit 3 includes a stripline input segment 8 and a microstrip line probe segment 7. The stripline input segment 8 and the microstrip line probe segment 7 are connected in sequence. The microstrip probe segment 7 does not have an outer ground plane and exposes the copper conductive strip, extending into the interior of the standard waveguide cavity 5.

[0038] The two metal wedge units 2 have identical structures and adopt a symmetrical design. They are symmetrically positioned within the standard waveguide cavity 5. The wedges are made of copper, 2.25mm thick, and spaced 30mm apart. The top and bottom edges of the wedges are flush with the copper conductor strip of the PCB unit 3. The edges of the wedges follow an exponential curve gradient, satisfying the formula...

[0039]

[0040] Based on the simulation results, the curve parameters were adjusted appropriately, and the wedge tip horizontally cut the TE inside the waveguide. 10 The vertical electric field in the mode forms a double conductor gradient structure with the inner wall of the standard waveguide cavity 5, guiding the upper and lower microwave signals with equal amplitude and phase to complete spatial synthesis in the waveguide cavity. The impedance of the double conductor structure conforms to the exponential curve function and has a smooth gradient, satisfying the principle of small microwave reflection and realizing impedance matching and mode matching under large bandwidth. The wedge base is left with a screw hole and is fixedly connected to the short-circuit wall of the standard waveguide cavity 5 with bolts. Its widest tip is welded to the copper conductor end of the corresponding upper and lower microstrip probe segment 7.

[0041] Among them, the base of the metal wedge unit 2 is provided with notches on both sides. The notches correspond to the transition area between the stripline input segment 8 and the microstrip probe segment 7 of the PCB board unit 3, so as to reduce the parasitic capacitance effect between the conductive band of the microstrip probe segment 7, achieve impedance matching, ensure the conversion between the TEM mode of the stripline and the quasi-TEM mode of the microstrip line, and suppress higher-order modes.

[0042] Furthermore, the standard waveguide cavity 5 adopts a BJ32 rectangular waveguide, with one end face open and connected to the flange 6. The other end face is provided with a short-circuit wall, and two first slots are opened along the outer edges of the upper and lower wide sides of the short-circuit wall. The slots are close to the inner wall of the wide side of the waveguide and extend along the normal direction of the outer surface of the short-circuit wall to connect to the metal cover plate 4. Two second slots are opened on the wide side of the end face where the standard waveguide cavity 5 connects to the PCB board unit 3, so that the microstrip line probe segment 7 of the PCB board unit 3 can extend into it.

[0043] Furthermore, the stripline input segment 8 of the PCB board unit 3 is electrically contacted and fixed to the metal cover plate 4 through the metal layers on its upper and lower surfaces. The fixing methods between the PCB board unit 3 and the metal cover plate 4 and the wall of the standard waveguide cavity 5 include adhesive bonding or connection with bolts through screw holes.

[0044] Furthermore, the metal wedge unit 2 is fixed to the short-circuit wall of the standard waveguide cavity 5 by bolts. The tip of the widest part of the metal wedge unit 2 is electrically connected to the conductor of the microstrip probe segment 7 by welding. To facilitate welding operations and reduce volume, the length of the standard waveguide cavity 5 is shorter than that of the metal wedge unit 2.

[0045] Furthermore, flange 6 adopts a standard flange design and is fixed with bolts, which facilitates connection and integration with other waveguide transmission lines and is beneficial for subsequent maintenance and repair.

[0046] Furthermore, the device can be integrated with the transmitting component as needed, with screw holes provided on the transmitting component housing, PCB board unit 3 and metal cover plate 4 and bolts used for fixing.

[0047] During assembly, the PCB board unit 3 must be fixed and the copper-clad metal layer glued first, then the metal wedge is fixed, and finally the soldering iron is inserted through the open end face of the flange side of the standard waveguide unit 1 to complete the soldering.

[0048] In summary, this invention uses four striplines to feed from the top and bottom wide edges of the short-circuit wall on one side of the waveguide, close to the slotted end of the inner wall of the waveguide. The feed probe adopts a microstrip line design, with no copper coating on the outside of the microstrip line. The copper conductor strip and the dielectric substrate are directly exposed. One PCB board contains two copper conductor strips, and two PCB boards are mounted and fixed on top and bottom to form a four-channel input.

[0049] Using a metal wedge structure instead of the ridge structure of a ridge waveguide allows for impedance matching and power combining of four striplines within a standard waveguide cavity. Compared to traditional double-sided double-ridge waveguide structures, the additional waveguide T-junction and quarter-impedance transformer structure can be omitted. The four end-fed 50-ohm coaxial lines can be equivalent to a parallel circuit, with an equivalent input impedance of 12.5 ohms after parallel connection, while the input impedance of the waveguide port is generally considered to be several hundred ohms. The impedance difference between the two is significant; if directly connected, it would cause a large proportion of microwave reflection, affecting transmission and combining efficiency. According to the microwave small reflection theory, if there are multiple discontinuities in the transmission line, and the reflection coefficient caused by each discontinuity is very small, the total reflection response depends on the linear superposition of reflections from each point, thus the higher-order reflection terms caused by back-and-forth reflections between discontinuities can be ignored. The wedge edge conforms to a logarithmic function curve, forming a smooth transition double-conductor structure with the inner wall of the waveguide. Welding it to the end of the microstrip line probe enables impedance matching under large bandwidth.

[0050] The notched base of the metal wedge suppresses parasitic capacitance between the metal wedge and the microstrip line probe, thus achieving a compact transition from stripline to microstrip line, impedance matching, ensuring the conversion between the TEM mode of the stripline and the quasi-TEM mode of the microstrip line, and suppressing higher-order modes. Using bolts to secure the remaining portion of the base to the waveguide short-circuit wall maintains good electrical contact.

[0051] Example

[0052] To verify the effectiveness of the present invention, the following experimental design was conducted.

[0053] The compact broadband four-way stripline-waveguide power combining device consists of three main structures: a standard waveguide unit 1, a metal wedge unit 2, and a PCB board unit 3.

[0054] The standard waveguide unit 1 includes a standard waveguide cavity 5, a flange 6, and a metal cover plate 4. One end of the standard waveguide cavity 5 is provided with a metal wall as a short surface, and slots are cut on the upper and lower wide sides of the metal wall to extend into the microstrip line probe 7 of the PCB board unit. The flange 6 is set on the open surface of the standard waveguide for connection with other waveguide devices. The metal cover plate is a natural extension of the wide side wall of the standard waveguide, with screw holes, and is connected and fixed to the PCB board unit 3 and the housing of the transmitting component.

[0055] The PCB board unit 3 has two groups, each group can be divided into stripline input section 8 and microstrip probe section 7; the stripline input section includes two copper conductors and upper and lower copper cladding, which can be fixed to the metal cover plate 4 by screw holes or glue, and can be directly fixed to the emitter component housing as needed, maintaining good electrical contact between the copper cladding ground plane of the PCB board unit 3 and the metal cover plate 4 and the emitter component housing.

[0056] There are two sets of metal wedge units 2, with a notched base. The base is fixed to the metal wall of the standard waveguide short surface using bolts. The tip of the widest edge of each metal wedge is welded to the end of the conductive strip of the upper and lower microstrip probe segments 7, respectively.

[0057] Figure 4 This is a compact, broadband four-channel stripline-waveguide power combiner with a total port voltage standing wave ratio (VSWR). Impedance matching can be achieved across the full bandwidth (2.6 GHz to 3.95 GHz) supported by the standard BJ32 waveguide, with a VSWR close to 1 at the center frequency and below 1.6 at the band edge frequencies.

[0058] Figure 5 The amplitude response of the four stripline ports of a compact broadband four-channel stripline-waveguide power combining device is shown. It can be seen that the amplitude consistency and balance of the four ports are good, with low loss. However, the amplitude is lower at the edge frequencies compared to the center frequency due to the relatively large standing wave ratio.

[0059] Figure 6 The phase response of the four stripline ports of a compact broadband four-way stripline-waveguide power combining device is shown. It can be seen that the phase balance of the four ports is good, and the signal phases of the different ports are completely consistent in the simulation. This is due to the horizontal and vertical symmetry of the four probes relative to the waveguide structure.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A compact broadband four-channel stripline-waveguide power combining device, characterized in that, It includes a standard waveguide unit (1), two metal wedge units (2), and two PCB board units (3), wherein: The standard waveguide unit (1) includes a standard waveguide cavity (5), a metal cover plate (4) and a flange (6), wherein the wide sidewall of the waveguide cavity (5) is integrally extended to form the metal cover plate (4), and the other end is provided with a flange (6). The two PCB board units (3) have three copper layers and two dielectric substrates. The outermost two copper layers serve as the ground plane, and the middle copper layer is printed as two copper conductors. The two PCB board units (3) are mirror-symmetrically arranged on the upper and lower wide sides of the standard waveguide cavity (5) and closely attached to the inner wall of the waveguide. Each PCB board unit (3) includes a stripline input segment (8) and a microstrip line probe segment (7). The stripline input segment (8) and the microstrip line probe segment (7) are connected in sequence. The microstrip line probe segment (7) does not have an outer ground plane, exposes the copper conductors, and extends into the interior of the standard waveguide cavity (5). The two metal wedge units (2) have the same structure and are symmetrical vertically. The two metal wedge units (2) are symmetrically arranged in the standard waveguide cavity (5). The upper and lower edges of the wedges are flush with the copper conductor strip of the PCB board unit (3). The side profile of the wedges gradually changes exponentially along the waveguide propagation direction. The tip of the wedge horizontally cuts the TE inside the waveguide. 10 The vertical electric field in the mode forms a double conductor gradient structure with the inner wall of the standard waveguide cavity (5), guiding two microwave signals with equal amplitude and opposite direction from the upper and lower PCB board units (3) to complete spatial synthesis in the waveguide cavity. The impedance of the double conductor structure conforms to the exponential curve function and is smoothly gradient, satisfying the principle of microwave small reflection, realizing impedance matching and mode matching under large bandwidth. The base of the wedge is fixedly connected to the short-circuit wall of the standard waveguide cavity (5), and its widest tip is electrically connected to the copper conductor end of the corresponding microstrip probe segment (7) above and below. Among them, the base of the metal wedge unit (2) is provided with notches on both sides. The notches correspond to the transition area of ​​the stripline input section (8) and the microstrip probe section (7) of the PCB board unit (3). This is used to reduce the parasitic capacitance effect between the wedge and the probe conductor, achieve impedance matching, ensure the conversion between the TEM mode of the stripline and the quasi-TEM mode of the microstrip line, and suppress the generation of higher-order modes.

2. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, In the standard waveguide unit, the standard waveguide cavity (5) adopts a rectangular waveguide. One end of the waveguide cavity is an open end and is connected to the flange (6), and the other end is a short-circuit end and forms a short-circuit wall. On the upper and lower sides of the short-circuit wall, and close to the inner wall of the wide side of the waveguide, a first slot is provided respectively. The first slot extends outward along the wide side wall of the waveguide and is integrally connected with the metal cover plate (4). Two second slots are provided on the wide side of the waveguide cavity end face opposite to the PCB board unit (3) for the microstrip probe segment (7) of the PCB board unit (3) to extend into the standard waveguide cavity (5).

3. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The stripline input segment (8) of the PCB board unit (3) is electrically contacted and fixed to the metal cover plate (4) through the metal layers on its upper and lower surfaces.

4. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The PCB board unit (3) is fixed to the metal cover plate (4) and the wall of the standard waveguide cavity (5) by means of adhesive bonding or by connection with bolts through screw holes.

5. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The metal wedge unit (2) is fixed to the short-circuit wall of the standard waveguide cavity (5) by bolts.

6. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The tip of the widest part of the metal wedge unit (2) is electrically connected to the conductor of the microstrip probe segment (7) by welding.

7. The compact broadband four-way stripline-waveguide power combining device according to claim 6, characterized in that, The length of the standard waveguide cavity (5) is shorter than that of the metal wedge unit (2).

8. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The flange (6) adopts a standard flange structure and is fixedly connected by bolts.

9. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The device is configured to be integrated with the transmitting component, wherein the transmitting component housing, PCB board unit (3) and metal cover plate (4) are respectively provided with screw holes and are fixed to each other by bolts.

10. The compact broadband four-way stripline-waveguide power combining device according to claim 1, characterized in that, The assembly process is as follows: First, the PCB board unit (3) is fixed on the standard waveguide unit (1) and the copper-clad metal layer is bonded to the metal cover plate (4); Next, the metal wedge unit (2) is fixed to the short-circuit wall of the standard waveguide cavity (5); Finally, the tip of the metal wedge unit (2) is soldered to the copper conductor end of the microstrip probe segment (7) by inserting a soldering iron through the open end face of the flange (6) on the standard waveguide unit (1).

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