A novel stripline-to-coaxial vertical conversion structure

Abstract

The present invention relates to a novel structure for vertical conversion from a microstrip line to a coaxial line. An arch-shaped strip line is designed at the connection between the microstrip line and the coaxial line. The metal pin of the coaxial line passes through the arch-shaped strip line and is welded to the upper printed circuit board. An isolation hole with the same diameter as the metal outer skin of the coaxial line is opened on the lower printed circuit board. The size of the arch-shaped strip line is adjusted to make the vertical conversion from the microstrip line to the coaxial line match. Seven metallized vias are drilled around the center of the metal pin of the coaxial line on the printed circuit board, and the metallized vias are spaced 45 degrees apart. The size and surrounding radius of the metallized vias are adjusted to achieve low-loss and smooth vertical conversion from the microstrip line to the coaxial line. The present invention has the characteristics of low insertion loss, simple and compact structure, and easy processing. After adding this conversion structure, efficient, compact, and low-loss feeding of the antenna by the microstrip line network can be realized, thereby improving the overall performance of the array antenna system.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna feeders, and proposes a design method for a novel vertical conversion from a strip line to a coaxial line. Applying this novel vertical conversion structure from a strip line to a coaxial line to the strip line network or circuit design can feed it and achieve efficient and low-loss transmission of radio frequency energy, and its structure is very simple. Furthermore, the overall performance of the antenna system can be improved. Therefore, it is very suitable for the design application of strip line networks. Background Art

[0002] With the rapid development of radio technology, more and more requirements are imposed on antennas. In addition to electrical characteristics requirements, antenna design must also take into account the appearance of the product, and antennas with advantages such as high efficiency and miniaturization are increasingly valued by the market. Due to its advantages such as light weight, small size, low profile, low cost, easy integration, and easy processing, the strip line has been deeply studied and widely used in fields such as communication and radar.

[0003] A feed network with good characteristics is crucial for the performance of an array antenna. The traditional vertical conversion structure from a strip line to a coaxial line is relatively complex and has certain losses. Moreover, as the frequency increases, its losses will also increase, affecting the overall performance of the antenna. In view of these drawbacks, the present invention proposes a novel design method for vertical conversion from a strip line to a coaxial line. This method greatly reduces the vertical conversion loss, and the structure is very simple and compact. Applying this novel vertical conversion structure from a strip line to a coaxial line to the strip line network or circuit design can feed it and achieve efficient and low-loss transmission of radio frequency energy. Furthermore, the overall performance of the antenna system can be improved. Therefore, it is very suitable for the design application of strip line networks. Summary of the Invention

[0004] Technical Problems to be Solved

[0005] In order to achieve vertical feeding of a strip line network, it is necessary to achieve stable and low-loss transmission from a coaxial line to a strip line. Due to the characteristics of the strip line structure, for the traditional vertical conversion structure from a strip line to a coaxial line, it is necessary to first convert the strip line into a microstrip line locally at the conversion end, and then vertically weld the microstrip and the coaxial line to achieve vertical feeding from the coaxial line to the strip line. In this way, the conversion structure is complex, and the conversion from the strip line to the microstrip line will cause transmission discontinuity and is prone to generating resonance points. Although local metallized vias can eliminate resonance, the exposed microstrip line part at the conversion end will still be affected by the external environment, resulting in instability and inconsistency of energy transmission. Moreover, as the frequency increases, the losses caused by the conversion also increase, thus affecting the electrical performance of the strip line network and even the overall antenna system.

[0006] To solve the defects of the above-mentioned traditional stripline-to-coaxial vertical conversion, a new design method for stripline-to-coaxial vertical conversion is proposed. The present invention has the characteristics of low insertion loss, simple and compact structure, easy processing, etc. After adding this conversion structure, the stripline network can achieve efficient, compact, and low-loss feeding for the antenna, thereby improving the overall performance of the array antenna system.

[0007] Technical Solution

[0008] A new type of stripline-to-coaxial vertical conversion structure, which is characterized by including an upper printed board and a lower printed board. The rectangular stripline is located in the middle layer of the upper printed board and the lower printed board. An arch-shaped stripline is connected to the end of the rectangular stripline. The arch-shaped stripline consists of a rectangular section and a semi-circular part. A metallized via with the same diameter as the coaxial metal inner pin is opened at the center position of the arch-shaped stripline. This metallized via passes through the arch-shaped stripline from the upper metal ground of the upper printed board until the lower metal ground of the lower printed board. An isolation hole with the same diameter as the coaxial metal outer skin is opened on the lower metal ground of the printed board. The coaxial metal pin passes through the lower printed board and the upper printed board from the metallized via and extends to the upper metal ground of the upper printed board, and the metal pin is welded to the upper metal ground of the upper printed board. Adjust the size of the arch-shaped stripline to make the stripline-to-coaxial vertical conversion match. Seven metallized vias are drilled around the center of the metal pin on the upper printed board and the lower printed board, and the metallized vias are spaced 45 degrees apart. Adjust the size and surrounding radius of the metallized vias to achieve low-loss and smooth vertical conversion from stripline to coaxial.

[0009] Beneficial Effects

[0010] A new type of stripline-to-coaxial vertical conversion structure proposed by the present invention has the following technical effects compared with the prior art:

[0011] 1. Wide bandwidth and low loss: The stripline-to-coaxial vertical conversion model can be equivalent to a two-port circuit model. To make the circuit model more matched, an arch-shaped stripline structure is added, which is equivalent to adding an inductor L and a capacitor C in the circuit. By appropriately adjusting the size of the arch-shaped structure, that is, adding appropriate L and C values in the circuit, finally the entire transmission model has a good matching effect within a relatively wide bandwidth. The stripline-to-coaxial vertical conversion of this design has very low loss within a wide operating bandwidth. Within a 40% (12 GHz - 18 GHz) operating bandwidth, the energy loss of the stripline-to-coaxial vertical conversion ≤ 0.35 dB.

[0012] 2. Good consistency and simple structure: Compared with the traditional conversion method, the stripline-to-coaxial vertical conversion structure of this design is very simple, easy to assemble and weld, and will not affect the electrical performance due to assembly and welding errors, and the external environment has no influence on the conversion effect, and the consistency is very good. Description of the Drawings

[0013] Figure 1 Side view of a novel stripline-to-coaxial vertical conversion structure

[0014] Figure 2 Front view of a novel stripline-to-coaxial vertical conversion structure

[0015] Figure 3 Curve of the standing wave of the stripline port of the novel stripline-to-coaxial vertical conversion varying with frequency

[0016] Figure 4 Curve of the standing wave of the coaxial port of the novel stripline-to-coaxial vertical conversion varying with frequency

[0017] Figure 5 Curve of the transmission S parameter from the coaxial port to the stripline port of the novel stripline-to-coaxial vertical conversion varying with frequency Specific implementation manner

[0018] The present invention will be further described below in conjunction with embodiments and drawings:

[0019] The above object of the present invention is mainly achieved by the following technical solutions:

[0020] First, aiming at the disadvantages of the traditional stripline-to-coaxial vertical conversion, the present invention realizes a design with low loss, wide bandwidth, and good consistency through the following structure.

[0021] In the first step, a rectangular stripline 1 with a line width of W1 = 1.5 mm is located in the middle layer of the upper printed board 5 and the lower printed board 6. The thickness of the printed boards is 1 mm each, and the dielectric constant is e r = 2.94. An arch-shaped stripline 2 is connected to its end. The arch-shaped stripline 2 consists of a rectangular section with dimensions of L2×W2 and a semicircle with a diameter of W2. A metallized via with the same diameter as the coaxial metal inner pin 3 is opened at the center of the arch-shaped stripline 2. The diameter D of the metal inner pin 3 i = 1.27 mm. This metallized via passes through the upper metal ground of the printed board 5, the arch-shaped stripline 2, and reaches the lower metal ground of the lower printed board 6. The metal inner pin 3 and the metal outer skin 4 together form a coaxial structure. Among them, the entire length of the arch is L1, L1 = L2 + W2 / 2, and the diameter of the metal outer skin 4 is D o .

[0022] In the second step, an isolation hole 7 with a diameter D o = 4.2 mm is opened on the lower metal ground of the lower printed board 6. The coaxial metal inner pin 3 passes through the upper printed board 5 and the lower printed board 6 from the metallized via and extends to the upper metal ground of the upper printed board 5, and the metal inner pin 3 is welded to the upper metal ground of the upper printed board 5. With the center of the coaxial metal inner pin 3 as the center and with R kWith a radius of D, 7 metallized vias with a diameter of D are drilled around the conversion structure on the printed circuit board, and the metallized vias are spaced 45 degrees apart. The dimensions of the arch-shaped strip line 2 can be roughly determined according to the formula: W2≈D k , L2≈λ / 4, where λ is the dielectric wavelength of the strip line, and the values of W2 and L2 are appropriately fine-tuned. Finally, W2 = 4.0mm and L2 = 2.7mm are obtained, so that the strip line to coaxial vertical conversion is matched. Appropriately adjust the values of D o and R k . Take D k =λ / 8, and D k =1.5mm, R k =4.2mm, to ensure the smoothness of energy output and achieve low-loss smooth vertical conversion from the strip line to the coaxial. Refer to k . Figure 1 .

[0023] Figure 3 Figure is the curve of the standing wave of the strip line to coaxial vertical conversion strip line changing with frequency. Within the working bandwidth of 40% (12GHz - 18GHz), the standing wave VSWR≤1.5.

[0024] Figure 4 Figure is the curve of the standing wave of the strip line to coaxial vertical conversion coaxial changing with frequency. Within the working bandwidth of 40% (12GHz - 18GHz), the standing wave VSWR≤1.5.

[0025] Figure 5 Figure is the curve of the transmission S parameter of the coaxial port to the strip line port of the strip line to coaxial vertical conversion changing with frequency. Within the working bandwidth of 40% (12GHz - 18GHz), the insertion loss≤0.35dB.

[0026] It can be seen from the simulation results that the new strip line to coaxial vertical conversion has very low losses within a relatively wide bandwidth, good consistency and a very simple structure form, with excellent electrical performance and structural compactness.

Claims

1. A novel stripline-to-coaxial vertical conversion structure, characterized in that, Comprising: The upper printed circuit board (5) and the lower printed circuit board (6), the rectangular strip line (1) is located in the middle layer of the upper printed circuit board (5) and the lower printed circuit board (6). An arch-shaped strip line (2) is connected to the end of the rectangular strip line (1). The arch-shaped strip line (2) consists of a rectangular section and a semi-circular part. A metallized via with the same diameter as the coaxial metal pin (3) is opened at the center of the circle of the arch-shaped strip line (2). The metallized via passes through the upper metal ground of the upper printed circuit board (5) through the arch-shaped strip line (2) until the lower metal ground of the lower printed circuit board (6). An isolation hole (7) with the same diameter as the coaxial metal outer skin (4) is opened on the lower metal ground of the printed circuit board (6). The coaxial metal pin (3) passes through the lower printed circuit board (6) and the upper printed circuit board (5) from the metallized via and extends to the upper metal ground of the upper printed circuit board (5), and the metal pin (3) is welded to the upper metal ground of the upper printed circuit board (5). Adjust the size of the arch-shaped strip line (2) to make the strip line to coaxial vertical conversion match. Around the center of the circle of the metal pin (3) on the upper printed circuit board (5) and the lower printed circuit board (6), with a radius of R k , where R k is 4.2 mm, 7 metallized vias (8) are drilled. The interval between the metallized vias is 45 degrees. The diameter D k of the metallized via (8) is 1.5 mm. Adjust the size and surrounding radius of the metallized via to achieve a low-loss and smooth vertical conversion from the strip line to the coaxial line; Among them, the dimensions of the rectangular section of the arch-shaped wire (2) are L2×W2, the diameter of the semi-circle of the arch-shaped wire (2) is W2, W2 = 4.0 mm, and L2 = 2.7 mm.

Images