Conformal waveguide transmission line

Abstract

The invention discloses a conformal waveguide transmission line, which comprises an outer side bending metal layer, an inner side bending metal layer and a gap between the outer side bending metal layer and the inner side bending metal layer from the outer side to the inner side, the outer side bent metal layer is provided with a bent waveguide groove and two parallel bent long choke grooves, and the bent long choke grooves are arranged on the upper side and the lower side of the bent waveguide groove respectively and are separated by a bent metal wall. The inner side bent metal layer is provided with two rows of periodic choke grooves, the periodic choke grooves are periodically arranged along the surface of the inner side bent metal layer and arranged on the upper side and the lower side of the bent waveguide groove respectively, the centers of the periodic choke grooves are periodically arranged along the inner wall of the bent long choke groove, and the interval is lambda g / 6-lambda g / 2. The filter can maintain stable main mode propagation characteristics, inhibits high-order mode excitation and energy leakage, has low insertion loss, excellent impedance matching performance and strong environmental adaptability, and is suitable for high-frequency systems such as aerospace and intelligent automobile radar.

Description

Technical Field

[0001] This invention relates to the field of passive devices, and more specifically to a waveguide transmission line that can be used in low-loss conformal antennas and devices. Background Technology

[0002] Existing transmission line technology for conformal antennas and devices is a key component for realizing high-frequency (especially millimeter-wave), highly integrated, non-planar platform (such as aircraft skin, automotive curved surfaces, and wearable devices) RF front-end interconnection. Typical applications include aerospace (phased array radar feed networks that fit the curved surfaces of the fuselage / wing), smart cars (77 GHz millimeter-wave radar integrated into curved surfaces such as bumpers and rearview mirrors), 5G / 6G communication (feeding millimeter-wave antennas that are not deployed on a planar surface in base stations or terminal equipment), and wearable and flexible electronics (flexible RF systems that are attached to the human body or clothing).

[0003] Existing conformal transmission lines (such as microstrip, GCPW, SIW) suffer from changes in geometric parameters (linewidth, spacing, dielectric thickness) due to bending when fitting to curved surfaces. This causes characteristic impedance mismatch, increased radiation loss, and mode distortion, which severely affects signal integrity, especially in the millimeter-wave band.

[0004] Compared to mainstream conformal transmission lines (such as conformal microstrip lines, GCPWs, SIWs, etc.), conformal waveguide transmission line technologies (such as curved metal waveguides produced by 3D printing or machining) exhibit significantly lower transmission losses at high frequencies (especially millimeter-wave and above) compared to conformal transmission lines with dielectrics (such as microstrips and SIWs). This makes them particularly suitable for efficiency-sensitive high-frequency systems. Furthermore, their all-metal enclosed structure provides excellent power carrying capacity, electromagnetic shielding, and interference immunity, making them suitable for high-reliability, high-power military and aerospace conformal antenna feeding scenarios.

[0005] However, for rigid rectangular waveguides, achieving conformal conformation (fitting any curved surface) requires high-precision metal additive manufacturing (such as SLM and EBM metal 3D printing) or special machining. High-precision 3D metal additive manufacturing often makes it difficult to control the surface roughness of the metal (affecting high-frequency conductor loss), while machined conformal metal waveguides typically have unavoidable gaps between the curved metal layers during assembly, which disrupts the continuity of the waveguide's inner wall current, leading to the excitation of higher-order modes, mode distortion, or radiation leakage. Therefore, proposing a high-performance conformal waveguide transmission line is essential. Summary of the Invention

[0006] This invention aims to solve the problems of high transmission loss and energy leakage faced by existing millimeter-wave transmission lines when applied to conformal carriers (such as curved or non-planar structures). It provides a conformable waveguide transmission line structure suitable for the millimeter-wave band, which effectively suppresses energy leakage, reduces transmission loss, and achieves good impedance matching over a wide bandwidth while ensuring good conformability. This improves the transmission performance and reliability of the system in high-frequency and high-integration scenarios.

[0007] A conformal waveguide transmission line includes an outer bent metal layer, an inner bent metal layer, and a gap between the outer bent metal layer and the inner bent metal layer, from the outside to the inside. The outer curved metal layer is provided with a curved waveguide groove and two parallel curved long choke grooves. The two curved long choke grooves are respectively located on the upper and lower sides of the curved waveguide groove and separated by the curved metal wall. The inner curved metal layer is provided with two rows of parallel periodic choke slots. The two rows of periodic choke slots are arranged periodically along the surface of the inner curved metal layer and are respectively placed on the upper and lower sides of the curved waveguide slot. The periodic choke slots are arranged periodically along the inner wall of the curved long choke slot, and the spacing between the periodic choke slots ranges from λg / 6 to λg / 2, where λg is the waveguide wavelength of the main mode TE10 mode.

[0008] Preferably, the shape of the periodic choke groove is any one of a circular groove, a square groove, or a rectangular groove.

[0009] Preferably, the outer radius of the inner curved metal layer is 8 mm, the width of the gap is 0.05 mm, and the inner radius of the outer curved metal layer is 8.05 mm.

[0010] Preferably, the cross-sectional dimensions of the curved waveguide groove are 1.27mm × 2.54mm.

[0011] Preferably, the cross-sectional dimensions of the curved long choke groove are 0.8mm × 1.2mm.

[0012] Preferably, the thickness of the curved metal wall is 0.7 mm.

[0013] Preferably, the periodic choke groove has a size of 1.02mm × 1.1mm, an inner chamfer of 0.5mm, and a periodic spacing of 1.47mm between each row of periodic choke grooves.

[0014] Preferably, 18 identical periodic choke slots are arranged on the inner curved metal layer with an outer radius of 8 mm, and the spacing between the upper and lower rows of periodic choke slots is 3.94 mm.

[0015] Preferably, the longitudinal distance between the center of the periodic choke groove and the inner wall of the choke groove and the center of the waveguide groove cross section is 1.97 mm.

[0016] Preferably, the waveguide transmission line is a semi-cylindrical ring structure or other curved surface structure.

[0017] This invention utilizes an alternating structure of periodic and long choke slots that conform to the periphery of a curved waveguide, enabling the waveguide to maintain stable dominant mode propagation characteristics even when assembled on curved or non-planar carriers, significantly suppressing higher-order mode excitation and energy leakage. Compared to traditional rectangular waveguides without cross-sectional treatment, this conformal waveguide transmission line exhibits lower insertion loss, better impedance matching performance, and stronger environmental adaptability in the millimeter-wave band. Simultaneously, its structure facilitates integration into high-frequency systems with stringent space and form factor requirements, such as aerospace, intelligent automotive radar, and wearable communication devices, effectively improving the transmission efficiency and reliability of millimeter-wave signals on complex carriers. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the conformal waveguide transmission line of the present invention (semi-cylindrical ring structure). Figure 2 This is a top view of the conformal waveguide transmission line of the present invention; Figure 3 This is a side view of the conformal waveguide transmission line of the present invention; Figure 4 This is a schematic diagram of the outer curved metal layer structure of the present invention; Figure 5 This is a schematic diagram of the inner curved metal layer structure of the present invention; Figure 6 This is a schematic cross-section (4) of the conformal waveguide transmission line of the present invention from the side view. Figure 7 This is a schematic cross-section (5) of the top view of the conformal waveguide transmission line of the present invention; Figure 8 This is a schematic cross-section (6) of the top view of the conformal waveguide transmission line of the present invention; Figure 9 This is a comparison of the simulation results of the reflection coefficient (|S11|) curves of the conformal waveguide transmission line of this invention with other transmission lines; Figure 10 This is a comparison of the simulation results of the transmission coefficient (|S21|) curves of the conformal waveguide transmission line of this invention with other transmission lines.

[0019] Among them, 1. Outer curved metal layer; 11. Curved waveguide groove; 12. Curved long choke groove; 121. Inner wall; 13. Curved metal wall; 2. Inner curved metal layer; 21. Periodic choke groove; 3. Gap; 4. Side view section; 5. Top view section; 6. Top view section. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] A conformal waveguide transmission line operates based on the ability of an interlaced choke structure to suppress the propagation of electromagnetic fields and waves. This eliminates the influence of gaps between bent metal layers during assembly on the discontinuity of the waveguide inner wall current and confines the field energy within the bent waveguide grooves. In this process, the proposed choke structure effectively blocks the lateral leakage of electromagnetic waves within the gaps along the waveguide, ultimately enabling the electromagnetic field and waves to propagate efficiently along the waveguide grooves.

[0022] This invention aims to address the high transmission loss and energy leakage problems encountered by existing millimeter-wave transmission lines when applied to conformal carriers (such as curved or non-planar structures). Traditional transmission lines with dielectrics or all-metal waveguides struggle to maintain stable electromagnetic properties on curved surfaces, leading to decreased signal integrity and transmission efficiency. To address this, this invention proposes a conformal waveguide transmission line structure suitable for the millimeter-wave band. By adapting a conformal interleaved structure of periodic and long choke slots around the waveguide periphery, it effectively suppresses energy leakage, reduces transmission loss, and achieves good impedance matching over a wide bandwidth while ensuring good conformal capability, thereby improving the transmission performance and reliability of the system in high-frequency, highly integrated scenarios.

[0023] This invention discloses a waveguide transmission line that can be used in low-loss conformal antennas and devices, such as... Figure 1 As shown, the waveguide transmission line is a semi-cylindrical ring structure (or other curved surface structures). Figure 2 and Figure 3 Top and side views of a conformal waveguide transmission line are given respectively. From the outside to the inside, it includes an outer bent metal layer 1, an inner bent metal layer 2, and a gap 3 between the outer bent metal layer 1 and the inner bent metal layer 2. The outer radius of the inner bent metal layer 2 is 8 mm, the gap 3 is 0.05 mm, and the inner radius of the outer bent metal layer 1 is 8.05 mm.

[0024] Furthermore, such as Figure 4As shown, the outer curved metal layer 1 includes a curved waveguide groove 11 and two parallel curved long choke grooves 12, with the two curved long choke grooves 12 positioned on the upper and lower sides of the curved waveguide groove 11 and separated by a curved metal wall 13. The cross-sectional dimensions of the curved waveguide groove are 1.27mm × 2.54mm, the cross-sectional dimensions of the curved long choke grooves are 0.8mm × 1.2mm, and the thickness of the metal wall 13 is 0.7mm.

[0025] Furthermore, such as Figure 5 As shown, the inner curved metal layer 2 includes two rows of parallel periodic choke grooves 21 (which can be circular, square, rectangular, etc.). The two rows of choke grooves 21 are periodically arranged along the surface of the inner curved metal layer 2, and the two rows of choke grooves 21 are respectively placed on the upper and lower sides of the curved waveguide groove 11. The size of the choke groove 21 is 1.02mm × 1.1mm, the inner chamfer is 0.5mm, and the periodic spacing of each row of choke grooves 21 is 1.47mm. Eighteen identical choke grooves 21 are arranged on the inner curved metal layer 2 with an outer radius of 8mm. The spacing between the upper and lower rows of choke grooves 21 is 3.94mm.

[0026] Furthermore, Figures 6 to 8 Schematic diagrams of section 4 of the side view and sections 5 and 6 of the top view of the conformal waveguide transmission line are given respectively. The center of the choke groove 21 is periodically arranged along the inner wall 121 of the curved long choke groove 12, wherein the longitudinal distance between the center of the choke groove 21 and the inner wall 121 and the center of the waveguide groove section is 1.97mm.

[0027] Figure 9 and Figure 10 The reflection coefficients (|S) of the proposed conformal waveguide transmission line and other transmission lines are given respectively when the gap 3 is 0.05 mm. 11 |) and transmission coefficient (|S) 21 |) Comparison of simulation results of the curves. It can be seen that the performance of the reflection coefficient and transmission coefficient of the curved waveguide deteriorates when no choke is loaded, only a long choke is loaded, and only a periodic choke is loaded. However, by adopting the proposed staggered choke structure, the curved waveguide can achieve conformal capability while also obtaining excellent electromagnetic wave transmission performance.

[0028] This invention discloses a conformal waveguide transmission line, comprising an outer curved metal layer, an inner curved metal layer, and a gap between them, from the outside to the inside. The outer curved metal layer has a curved waveguide groove and two parallel curved long choke grooves, which are located on the upper and lower sides of the curved waveguide groove and separated by a curved metal wall. The inner curved metal layer has two rows of periodic choke grooves, which are periodically arranged along the surface of the inner curved metal layer and located on the upper and lower sides of the curved waveguide groove. Their centers are periodically arranged along the inner wall of the curved long choke grooves, with a spacing of λg / 6 to λg / 2. This invention can maintain stable primary mode propagation characteristics, suppress higher-order mode excitation and energy leakage, and has low insertion loss, excellent impedance matching performance, and strong environmental adaptability, making it suitable for high-frequency systems such as aerospace and intelligent automotive radar.

[0029] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A conformal waveguide transmission line, characterized in that, From the outside to the inside, it includes an outer curved metal layer (1), an inner curved metal layer (2), and a gap (3) between the outer curved metal layer (1) and the inner curved metal layer (2). The outer curved metal layer (1) is provided with a curved waveguide groove (11) and two curved long choke grooves (12) parallel to it. The two curved long choke grooves (12) are respectively placed on the upper and lower sides of the curved waveguide groove (11) and separated by the curved metal wall (13). The inner curved metal layer (2) is provided with two rows of parallel periodic choke grooves (21). The two rows of periodic choke grooves (21) are arranged periodically along the surface of the inner curved metal layer (2) and are respectively placed on the upper and lower sides of the curved waveguide groove (11). The center of the periodic choke (21) is arranged periodically along the inner wall (121) of the curved long choke (12), and the spacing of the periodic choke (21) is in the range of λg / 6~λg / 2, where λg is the waveguide wavelength of the main mode TE10 mode.

2. The conformal waveguide transmission line according to claim 1, characterized in that, The shape of the periodic choke groove (21) can be any one of a circular groove, a square groove, or a rectangular groove.

3. The conformal waveguide transmission line according to claim 1, characterized in that, The outer radius of the inner curved metal layer (2) is 8 mm, the width of the gap (3) is 0.05 mm, and the inner radius of the outer curved metal layer (1) is 8.05 mm.

4. The conformal waveguide transmission line according to claim 1, characterized in that, The cross-sectional dimensions of the curved waveguide groove (11) are 1.27mm × 2.54mm.

5. The conformal waveguide transmission line according to claim 1, characterized in that, The cross-sectional dimensions of the curved long choke groove (12) are 0.8mm × 1.2mm.

6. The conformal waveguide transmission line according to claim 1, characterized in that, The thickness of the curved metal wall (13) is 0.7 mm.

7. The conformal waveguide transmission line according to claim 1, characterized in that, The periodic choke groove (21) has a size of 1.02mm×1.1mm, an inner chamfer of 0.5mm, and a periodic spacing of 1.47mm between each row of periodic choke grooves (21).

8. The conformal waveguide transmission line according to claim 7, characterized in that, Eighteen identical periodic choke slots (21) are arranged on the inner curved metal layer (2) with an outer radius of 8 mm, and the spacing between the upper and lower rows of periodic choke slots (21) is 3.94 mm.

9. The conformal waveguide transmission line according to claim 1, characterized in that, The longitudinal distance between the center of the periodic choke groove (21) and the inner wall (121) and the center of the waveguide groove cross section is 1.97 mm.

10. The conformal waveguide transmission line according to any one of claims 1-9, characterized in that, The waveguide transmission line is a semi-cylindrical ring structure or other curved surface structure.

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