An adjustable coaxial microstrip transition matching structure

Abstract

The utility model discloses a kind of adjustable coaxial microstrip conversion matching structure, belong to signal communication field.The structure includes cavity structural member, radio frequency coaxial outer conductor, radio frequency coaxial inner conductor, printed board microstrip line, radio frequency printed board, air cavity and tuning structure.Radio frequency coaxial inner conductor is welded with microstrip line by soldering tin, air cavity is arranged below it, and air cavity depth is adjusted by threaded tuning structure, to change differential capacitance and realize impedance matching.The utility model overcomes the problem of high cost and complex process of existing gold ribbon crimping mode, can optimize port standing wave ratio to 1.3:1 in 30-40GHz frequency band, return loss is improved by 5-10dB, with the advantages of debugging flexible, stable structure, strong compatibility.

Description

Technical Field

[0001] This utility model relates to the field of signal communication technology, and in particular to an adjustable coaxial microstrip conversion matching structure. Background Technology

[0002] In the field of signal communication, especially in high-frequency communication systems, coaxial microstrip conversion structures are key components for signal interface conversion. With the increasing demands for system capacity, bandwidth, and frequency from technologies such as radar and communication, impedance matching issues in high-frequency transmission are becoming increasingly prominent. Existing technologies for coaxial microstrip conversion mainly employ methods such as welding, gold tape crimping, or lamination. Among these, gold tape crimping is widely used due to its superior RF performance, but it has significant drawbacks: First, the cost of gold tape and glass beads is high, and the gold layer thickness needs to reach at least 1.5 μm (military standards require at least 3 μm) to ensure bonding reliability; second, the manufacturing process is complex, relying on dedicated bonding or crimping equipment, increasing manufacturing difficulty and cost.

[0003] Gold strip crimping, which involves crimping gold strip onto a microstrip line and then molding it into the inner conductor of the RF connector and fixing it in place, can reduce the impact of matching characteristics. However, it lacks flexibility in adjusting the matching state and is prone to problems such as high port VSWR and signal oscillation at high frequencies. Therefore, there is an urgent need for a low-cost, simple, and tunable matching structure to overcome these limitations. Utility Model Content

[0004] The purpose of this invention is to provide an adjustable coaxial microstrip conversion matching structure that achieves continuous optimization of impedance matching through an adjustable air cavity design, while reducing cost and process requirements.

[0005] This utility model is achieved using the following technical solution: an adjustable coaxial microstrip conversion matching structure, characterized in that it includes a cavity structure, an RF coaxial outer conductor, an RF coaxial inner conductor, a printed circuit board microstrip line, an RF printed circuit board, an air cavity, and a tuning structure, characterized in that: the cavity structure is used to fix the RF printed circuit board and the RF coaxial outer conductor, the RF coaxial inner conductor is connected to the printed circuit board microstrip line, the air cavity is disposed on the RF printed circuit board and located below the connection between the RF coaxial inner conductor and the printed circuit board microstrip line, and the tuning structure is operably connected to the air cavity to adjust its depth.

[0006] Furthermore, the tuning structure is a threaded tuning screw, which continuously adjusts the depth of the air cavity through rotational motion.

[0007] Furthermore, the inner conductor of the radio frequency coaxial line is soldered to the microstrip line of the printed circuit board to form a signal transmission path.

[0008] Furthermore, the cavity structure is connected to the radio frequency printed circuit board and the radio frequency coaxial external conductor by means of screws to ensure mechanical stability.

[0009] Furthermore, the radio frequency coaxial outer conductor and the cavity structure are connected by a threaded connection to achieve grounding continuity.

[0010] Furthermore, the depth of the air cavity is continuously adjustable through a tuning structure to optimize the impedance matching state.

[0011] Furthermore, the tuning structure is accessed from the bottom of the radio frequency printed circuit board and the adjusted air cavity depth is fixed by a locking mechanism.

[0012] The adjustable coaxial microstrip conversion matching structure described in this utility model has the following advantages: By adjusting the air cavity depth, the differential capacitance can be optimized in real time, achieving good impedance matching within the 30-40GHz frequency band. Actual measurement data shows that port return loss is optimized by approximately 5-10dB, and the VSWR is improved from 1.6:1 in the conventional structure to 1.3:1, effectively suppressing signal amplitude fluctuations and oscillations.

[0013] It abandons the high-cost materials and specialized equipment of the gold strip crimping method, and can achieve debugging only through the threaded tuning structure, thus reducing production costs and process complexity.

[0014] With the help of a vector network analyzer, testing and debugging can be carried out simultaneously. The depth of the air cavity is continuously adjustable. After debugging, the state is fixed by a locking mechanism to ensure long-term reliability.

[0015] It is suitable for conversion scenarios between coaxial inner conductors and microstrip lines of different sizes, enhancing the versatility of the structure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of an adjustable coaxial microstrip conversion matching structure; In the figure, 1-cavity structure, 2-RF coaxial outer conductor, 3-RF coaxial inner conductor, 4-solder, 5-printed board microstrip line, 6-RF printed board, 7-air cavity, 8-tuning structure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Example

[0020] like Figure 1 As shown, this embodiment provides an adjustable coaxial microstrip conversion matching structure, which mainly consists of a cavity structure 1, an RF coaxial outer conductor 2, an RF coaxial inner conductor 3, solder 4, a printed circuit board microstrip line 5, an RF printed circuit board 6, an air cavity 7, and a tuning structure 8.

[0021] The cavity structure 1 is used to fix the RF printed circuit board 6 and the RF coaxial outer conductor 2. The RF coaxial outer conductor 2 is connected to the cavity structure 1 by threads or crimping to ensure mechanical stability and grounding continuity. The RF coaxial inner conductor 3 extends to the surface of the RF printed circuit board 6 and is soldered to the microstrip line 5 of the printed circuit board via solder 4 to achieve signal transmission. An air cavity 7 is formed below the soldering position of the RF coaxial inner conductor 3 and the microstrip line 5 on the RF printed circuit board 6. The depth of the air cavity 7 is adjusted by a tuning structure 8, which uses a threaded tuning screw. By rotating the tuning structure 8, the depth of the air cavity 7 can be continuously changed, thereby adjusting the differential capacitance at the soldering point.

[0022] During assembly, the RF printed circuit board 6 is first installed into the pre-reserved slot of the cavity structure 1 and secured with screws. Then, the RF coaxial outer conductor 2 is mated with and locked to the cavity structure 1, ensuring that the RF coaxial inner conductor 3 is aligned with the microstrip line 5 on the printed circuit board. Next, solder 4 is used to solder the end of the RF coaxial inner conductor 3 to the microstrip line 5 on the printed circuit board. Finally, the depth of the air cavity 7 is precisely controlled by screwing the tuning structure 8 into the bottom of the RF printed circuit board 6. After installation, the entire structure forms a stable coaxial microstrip conversion interface.

[0023] The working principle is as follows: the impedance Z is determined by the differential inductance L and the differential capacitance C, i.e., Z = L / C. By adjusting the depth of the air cavity 7, the capacitance C between the inner conductor 3 of the RF coaxial cable and the ground cavity can be changed: when the depth of the air cavity 7 increases, the equivalent capacitance C decreases; when the depth decreases, C increases. Thus, while keeping the inductance L basically constant, the Z value can be made close to the ideal matching state by continuously adjusting C.

[0024] In practice, this RF coaxial microstrip conversion scheme allows for calculations to match the conversion impedance between the inner conductor and the microstrip line of different sizes. The impedance is then matched by fabricating air cavities of varying depths. This method is simple and easy to implement, requiring no additional specialized tools to achieve continuous adjustment of the air cavity size (i.e., the capacitance from the port to ground). Furthermore, it allows for simultaneous testing and adjustment on a vector network analyzer, and the adjusting screw can be tightened after achieving optimal matching.

[0025] The technical effects of this embodiment are significant: First, the adjustable air cavity 7 enables continuous optimization of impedance matching, avoiding the high cost and complex process of existing gold strip crimping methods; second, the adjustment process is simple and reliable, requiring no additional tools, and the state is stable after adjustment; finally, this structure is suitable for various coaxial inner conductor sizes, has strong compatibility, and effectively suppresses signal oscillation and amplitude fluctuations in the 30-40GHz high-frequency range, improving the reliability of the communication system.

[0026] The above embodiments describe the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Modifications and variations made by those skilled in the art without departing from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. An adjustable coaxial microstrip conversion matching structure, characterized in that, The device includes a cavity structure (1), an RF coaxial outer conductor (2), an RF coaxial inner conductor (3), a printed circuit board microstrip line (5), an RF printed circuit board (6), an air cavity (7), and a tuning structure (8). The cavity structure (1) is used to fix the RF printed circuit board (6) and the RF coaxial outer conductor (2). The RF coaxial inner conductor (3) is connected to the printed circuit board microstrip line (5). The air cavity (7) is disposed on the RF printed circuit board (6) and located below the connection between the RF coaxial inner conductor (3) and the printed circuit board microstrip line (5). The tuning structure (8) is operably connected to the air cavity (7) to adjust its depth.

2. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The tuning structure (8) is a threaded tuning screw that continuously adjusts the depth of the air cavity (7) through rotational motion.

3. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The radio frequency coaxial inner conductor (3) is soldered to the printed circuit board microstrip line (5) via solder (4) to form a signal transmission path.

4. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The cavity structure (1) is connected to the radio frequency printed circuit board (6) and the radio frequency coaxial outer conductor (2) by means of screw fixing to ensure mechanical stability.

5. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The radio frequency coaxial outer conductor (2) and the cavity structure (1) are connected by a threaded connection to achieve grounding continuity.

6. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The depth of the air cavity (7) is continuously adjustable through the tuning structure (8) to optimize the impedance matching state.

7. The adjustable coaxial microstrip conversion matching structure according to claim 1, characterized in that, The tuning structure (8) is accessed from the bottom of the radio frequency printed circuit board (6) and the depth of the adjusted air cavity (7) is fixed by a locking mechanism.

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