A waveguide transition structure for a single-layer LOP antenna

Abstract

The application relates to the field of waveguide transmission lines, and discloses a waveguide conversion structure for a single-layer LOP antenna, which comprises a conversion structure; the bottom surface of the conversion structure is a plane, a waveguide cavity is formed in the inside of the conversion structure and is open to the bottom surface, a side opening is formed in one side of the conversion structure, and the bottom surface is used for being attached to the surface of a printed circuit board; the waveguide cavity is composed of an E-plane rectangular waveguide cavity and a matching cavity which are in communication with each other, the bottom surface of the E-plane rectangular waveguide cavity is flush with the bottom surface of the matching cavity, and the bottom surfaces jointly form an opening through which the waveguide cavity is open to the bottom surface; the first end of the E-plane rectangular waveguide cavity is communicated with the side opening, and at least one level of steps which protrude to the inside is arranged on the top wall of the second end of the E-plane rectangular waveguide cavity; the waveguide conversion structure can realize the conversion from a double-ridge waveguide to a rectangular waveguide, simultaneously complete the conversion of the electromagnetic wave propagation direction, and has excellent transmission performance.

Description

Technical Field

[0001] This invention relates to the field of waveguide transmission lines, and more particularly to a waveguide conversion structure for a single-layer LOP antenna. Background Technology

[0002] Traditional antennas use a non-LOP (Line-on-Package) feeding method, where the chip is fed to the antenna via package pins and PCB microstrip lines. This feeding method has significant line loss, and near-field radiation can cause surface wave interference on the board. Currently, the millimeter-wave radar field is beginning to use Launch on Package (LoP) antennas, an advanced antenna packaging technology. Its core principle is to transmit radio frequency signals directly from the waveguide port of the chip package to the waveguide antenna. This offers lower line loss, a higher signal-to-noise ratio, allows the use of low-frequency substrates, and reduces costs.

[0003] Due to the size limitations of the LOP millimeter-wave radar MMIC itself, the waveguide port of the chip package is relatively small, especially for chips with 8T8R and more ports. Therefore, chip manufacturers usually design the waveguide port to be dog-bone shaped, which can be classified as a double-ridged waveguide, in order to arrange as many transceiver ports as possible in a smaller package area.

[0004] To complete the routing design within a limited space, the transmission line connected to the chip waveguide port can use an E-plane waveguide. However, E-plane waveguides with ridges are difficult to mold and manufacture. Therefore, the conversion structure between double-ridged waveguides and rectangular waveguides has become an important joint of waveguide transmission lines. Summary of the Invention

[0005] To address the aforementioned shortcomings and solve the conversion problem between the double-ridged waveguide and rectangular waveguide in LOP millimeter-wave radar MMIC, this invention provides a single-layer waveguide transmission line that is simple in structure, smaller in size, and easy to manufacture.

[0006] A waveguide conversion structure for a single-layer LOP antenna includes: Transformation structure; The bottom surface of the conversion structure is a plane, and a waveguide cavity that opens to the bottom surface is formed inside the conversion structure. The waveguide cavity has a side opening on one side of the conversion structure, and the bottom surface is used to fit against the surface of the printed circuit board. The waveguide cavity is composed of interconnected E-plane rectangular waveguide cavities and matching cavities. The bottom surface of the E-plane rectangular waveguide cavity is flush with the bottom surface of the matching cavity, and together they form an opening of the waveguide cavity to the bottom surface. The first end of the E-plane rectangular waveguide cavity is connected to the side opening, and the top wall of the second end of the E-plane rectangular waveguide cavity is provided with at least one step protruding inward. The matching cavity is located below the second end of the E-plane rectangular waveguide cavity. The two wide sides of the matching cavity have ridges protruding into the cavity on their inner walls, so that the cross-section of the matching cavity parallel to the bottom surface is H-shaped. The gap width between the two ridges is greater than or equal to the narrow side width of the E-plane rectangular waveguide cavity.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The waveguide conversion structure proposed in this invention can realize the conversion from a double-ridged waveguide to a rectangular waveguide, and at the same time complete the change of electromagnetic wave propagation direction. It also has low loss, small reflection coefficient, and excellent transmission performance.

[0008] 2. The waveguide conversion structure introduced in this invention is a single-layer design. The width of the gap between the double ridges of the matching cavity is greater than or equal to the narrow side width of the E-plane waveguide, which facilitates the use of injection molding or CNC machine tools and other processing technologies, making it highly feasible to manufacture. 3. This invention uses an E-plane rectangular waveguide to connect waveguide channels, which enables multi-port wiring within a limited package area, improving the flexibility and feasibility of waveguide channel routing design; 4. The conversion structure of the present invention can be soldered onto the metal plating layer of the printed circuit board to avoid signal leakage and ensure good isolation between channels. Attached Figure Description

[0009] Figure 1 This is a three-dimensional exploded view of the waveguide conversion structure and chip port in this invention; Figure 2 This is a top view of the waveguide conversion structure and chip port in this invention; Figure 3 This is a side view of the waveguide conversion structure in this invention; Figure 4 This is a three-dimensional perspective view of the internal cavity of the waveguide conversion structure in this invention; Figure 5 This is a three-dimensional exploded view of the internal cavity of the waveguide conversion structure in this invention; Figure 6 This is a three-dimensional exploded view of the waveguide conversion structure traces and multi-port chip in this invention; Figure 7 This is a top view of the waveguide conversion structure traces and multi-port chip in this invention; Figure 8 These are the simulation results of the reflection coefficient of the waveguide conversion structure in this invention; Figure 9 These are the simulation results of the transmission coefficient of the waveguide conversion structure in this invention.

[0010] The attached figures are labeled as follows: 1: Transformation Structure 2: Internal cavity of the conversion structure 21: E-plane rectangular waveguide cavity 211: Steps 22: Matching cavity 3: Printed Circuit Board 31: Power supply port. Detailed Implementation

[0011] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” or “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0012] In a double-ridged waveguide, the electric field energy is highly concentrated in the narrow gap between the upper and lower ridges. This phenomenon is also observed in the energy within the port of a chip waveguide designed with a dog-bone shape. In contrast, the electric field in a rectangular waveguide is uniformly distributed along its wide side, exhibiting a sinusoidal half-wave characteristic. Therefore, direct connection between a rectangular waveguide and a double-ridged waveguide results in severe impedance mismatch. This invention achieves efficient electromagnetic wave transmission from the chip waveguide port to the matching cavity by incorporating a matching cavity with double ridges. Since the width between the ridges of the matching cavity is greater than or equal to the narrow side length of the E-plane waveguide, the E-plane rectangular waveguide can also strongly confine the central electric field, thus smoothly completing the transmission from the matching cavity to the rectangular waveguide. The metal plating, together with the other three faces of the semi-open E-plane rectangular waveguide cavity, forms a closed waveguide cavity with two ports, enabling electromagnetic wave transmission while effectively preventing signal leakage. A step is provided on the upper wall of the end of the E-plane rectangular waveguide channel. Its function is to reduce the reflection of electromagnetic waves when they are redirected. Specifically, the energy emitted by the chip is vertically transmitted through the waveguide cavity of the printed circuit board into the conversion structure, where it undergoes a gradual redirection at the step, and then is transmitted laterally along the E-plane rectangular waveguide cavity to the waveguide port, and finally reaches the antenna feed end. The same principle applies to reception.

[0013] A waveguide conversion structure for a single-layer LOP antenna includes: a conversion structure 1, wherein the conversion structure 1 is formed by etching a semi-open waveguide cavity 2 on a metal plate or other conductive material, the bottom surface of the conversion structure 1 is used to connect to a printed circuit board 3, and an open side surface is used to connect to a waveguide channel.

[0014] The waveguide cavity 2 is formed by interlocking and communicating with an E-plane rectangular waveguide cavity 21 and a matching cavity 22, with the bottom surface of the E-plane rectangular waveguide cavity 21 flush with the bottom surface of the matching cavity 22. One port of the E-plane rectangular waveguide cavity 21 is used to connect to the waveguide channel, and an n (n≥1)-level step 211 is provided at the other end. The matching cavity 22 has an inwardly concave ridge at the center of its two wide sides, i.e., the shape of the E-plane cross-section is H-shaped. The matching cavity 22 is used to connect to the feed port 31 on the printed circuit board 3, and the projection area of ​​the matching cavity 22 on the E-plane completely covers the feed port 31. The conversion structure 1 is soldered onto the metal plating layer of the printed circuit board 3.

[0015] The power supply port 31 of the printed circuit board 3 is in the shape of a dog-bone shape or other shapes that can be classified as double-ridge waveguides. The gap width between the two ridges is equal to the narrow side width of the E-plane rectangular waveguide cavity; the side end face of each ridge protruding into the cavity is coplanar with the inner wall of one narrow side of the E-plane rectangular waveguide cavity in the vertical direction.

[0016] The number of steps is one, and the width of the step is equal to the narrow side width of the E-plane rectangular waveguide cavity.

[0017] The end sidewall of the step is connected to the inner wall of the end face of the second end of the E-plane rectangular waveguide cavity in the same plane.

[0018] The height of the matching cavity along the direction perpendicular to the bottom surface is 0.2 to 0.45 times the center wavelength of the electromagnetic wave within the predetermined operating frequency band.

[0019] The ridge has a chamfered or beveled structure at the edge position facing the interior of the matching cavity.

[0020] The waveguide conversion structure for a single-layer LOP antenna further includes: the printed circuit board; the printed circuit board has a feed port, and the matching cavity covers the entire edge contour of the feed port in the vertical orthographic projection area of ​​the printed circuit board surface.

[0021] The printed circuit board has a metal plating layer on the surface facing the conversion structure, and the bottom surface of the conversion structure is fixed to the metal plating layer by pressure welding; the opening on the bottom surface of the waveguide cavity is completely closed by the metal plating layer, together forming a closed transmission cavity with two ports.

[0022] The power supply port on the printed circuit board is in the shape of a dog bone, or in the shape of a double-ridged waveguide with the center of the wide side protruding inward.

[0023] The printed circuit board has multiple power supply ports arranged in an array; the conversion structure has multiple parallel waveguide cavities inside; the openings of two adjacent waveguide cavities are separated by metal ribs of the conversion structure, and the lower end face of each metal rib is flush with the bottom surface of the conversion structure and connected to the printed circuit board.

[0024] Specifically, refer to Figure 1-2 As shown, it includes: a conversion structure 1 and a printed circuit board 3 that docks with it, the conversion structure 1 being bonded to the printed circuit board 3. The printed circuit board 3 has a waveguide feed port 31 etched on it, the waveguide feed port 31 being a dog-bone shape.

[0025] The conversion structure 1 is formed by etching an open waveguide cavity 2 onto a metal plate or other conductive material. After the conversion structure 1 is soldered onto the metal plating layer of the printed circuit board 3, the metal plating layer and the other three surfaces of the E-plane rectangular waveguide cavity 2 form a closed waveguide cavity with two ports, thereby enabling the transmission of electromagnetic waves and preventing signal leakage.

[0026] Reference Figure 3-5 As shown, the waveguide cavity 2 is formed by interlocking and communicating with the E-plane rectangular waveguide cavity 21 and the matching cavity 22 in the vertical direction, and the bottom surface of the E-plane rectangular waveguide cavity 21 is flush with the bottom surface of the matching cavity 22.

[0027] The E-plane rectangular waveguide cavity 21 has a wide side length of A1 and a narrow side width of B1. One port is used to connect to the waveguide channel, and a step 211 is provided at the other end.

[0028] The width of the step 211 is equal to the width of the narrow side of the E-plane rectangular waveguide. The length of the step is L1 and the height is H1. The step is located on the upper wall of the E-plane waveguide cavity and is connected to a side wall opposite to the port of the E-plane rectangular waveguide cavity.

[0029] The matching cavity 22 has a length of A2 and a width of B2, and its projection area on surface E completely covers the power supply port 31 of the printed circuit board 3.

[0030] The matching cavity 22 has an inwardly concave ridge in the middle of its two wide sides, meaning the cross-section of the E-plane is H-shaped, and the width of the ridge is L2. The double-ridge structure can achieve strong confinement of electromagnetic waves in the central region, which can reduce the impedance mismatch between the feed port 31 and the conversion structure 1.

[0031] The width of the gap between the two ridges of the matching cavity 22 is set as W, and the value of W is equal to the narrow side width B1 of the E-plane rectangular waveguide cavity. While realizing a single-layer structure, the feasibility of single-sided draft molding in injection molding or CNC machine tool processing is ensured.

[0032] Furthermore, the height of the matching cavity 22 is H2, and the value of H2 ranges from 0.2 times the working wavelength to 0.45 times the working wavelength. The value of H2 needs to be adjusted according to the actual matching situation. Furthermore, the ridge of the matching cavity 22 can be chamfered or beveled according to actual processing requirements.

[0033] Reference Figure 6-7 As shown, for multi-port chips, the structure proposed in this invention can achieve a compact arrangement, and the width of the metal ribs between each port can meet the welding requirements. Therefore, it can ensure that the isolation between each channel of the multi-port chip meets the actual engineering requirements.

[0034] Reference Figure 8-9 As shown, the waveguide conversion structure for single-layer LOP antennas proposed in this invention has a low reflection coefficient and transmission loss in the operating frequency band of millimeter-wave radar, proving that the conversion structure in this invention can effectively complete the conversion from double-ridge waveguide to rectangular waveguide. Moreover, the single-layer structure design meets the requirements of injection molding or CNC machine tool processing technology, and is small in size and simple in structure, thus possessing strong engineering application value.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waveguide conversion structure for a single-layer LOP antenna, characterized in that, include: Transformation structure (1); The bottom surface of the conversion structure (1) is a plane, and a waveguide cavity (2) that opens to the bottom surface is formed in the recess of the conversion structure (1). The waveguide cavity (2) has a side opening on one side of the conversion structure (1). The bottom surface is used to fit against the surface of the printed circuit board (3). The waveguide cavity (2) is composed of an E-plane rectangular waveguide cavity (21) and a matching cavity (22) that are interconnected. The bottom surface of the E-plane rectangular waveguide cavity (21) is flush with the bottom surface of the matching cavity (22) and together they form an opening of the waveguide cavity (2) to the bottom surface. The first end of the E-plane rectangular waveguide cavity (21) is connected to the side opening, and the top wall of the second end of the E-plane rectangular waveguide cavity (21) is provided with at least one step (211) protruding inward. The matching cavity (22) is located below the second end of the E-plane rectangular waveguide cavity (21). The two wide sides of the matching cavity (22) have ridges protruding into the cavity on their inner walls, so that the cross section of the matching cavity (22) parallel to the bottom surface is H-shaped. The gap width between the two ridges is greater than or equal to the narrow side width of the E-plane rectangular waveguide cavity (21).

2. The waveguide conversion structure for a single-layer LOP antenna according to claim 1, characterized in that, The gap width between the two ridges is equal to the narrow side width of the E-plane rectangular waveguide cavity (21); the side end face of each ridge protruding into the cavity is coplanar with the inner wall of one narrow side of the E-plane rectangular waveguide cavity (21) in the vertical direction.

3. The waveguide conversion structure for a single-layer LOP antenna according to claim 1, characterized in that, The number of steps (211) is one, and the width of the steps (211) is equal to the width of the narrow side of the E-plane rectangular waveguide cavity (21).

4. The waveguide conversion structure for a single-layer LOP antenna according to claim 3, characterized in that, The end sidewall of the step (211) is connected to the inner wall of the end face of the second end of the E-plane rectangular waveguide cavity (21) in the same plane.

5. The waveguide conversion structure for a single-layer LOP antenna according to claim 1, characterized in that, The height of the matching cavity (22) along the direction perpendicular to the bottom surface is 0.2 to 0.45 times the center wavelength of the electromagnetic wave in the predetermined operating frequency band.

6. The waveguide conversion structure for a single-layer LOP antenna according to claim 1, characterized in that, The ridge has a chamfered or beveled structure at the edge position facing the interior of the matching cavity (22).

7. The waveguide conversion structure for a single-layer LOP antenna according to any one of claims 1 to 6, characterized in that, Also includes: The printed circuit board (3); the printed circuit board (3) has a power supply port (31), and the matching cavity (22) covers the entire edge contour of the power supply port (31) in the vertical orthographic projection area on the surface of the printed circuit board (3).

8. The waveguide conversion structure for a single-layer LOP antenna according to claim 7, characterized in that, The printed circuit board (3) has a metal plating layer on the surface facing the conversion structure (1), and the bottom surface of the conversion structure (1) is fixed to the metal plating layer by pressure welding; the opening on the bottom surface of the waveguide cavity (2) is completely closed by the metal plating layer, together forming a closed transmission cavity with two ports.

9. The waveguide conversion structure for a single-layer LOP antenna according to claim 7, characterized in that, The power supply port (31) on the printed circuit board (3) is in the shape of a dog bone, or in the shape of a double-ridged waveguide with the center of the wide side protruding inward.

10. The waveguide conversion structure for a single-layer LOP antenna according to claim 7, characterized in that, The printed circuit board (3) has multiple power supply ports (31) arranged in an array; the conversion structure (1) has multiple parallel waveguide cavities (2) inside; the openings of two adjacent waveguide cavities (2) are separated by a metal rib isolation structure of the conversion structure (1), and the lower end face of each metal rib is flush with the bottom surface of the conversion structure (1) and connected to the printed circuit board (3).

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