Microstrip conformal low pass filter and satellite communication system

Abstract

The application provides a microstrip conformal low-pass filter and a satellite communication system, and the microstrip conformal low-pass filter comprises a dielectric substrate, a first metal layer arranged on a first surface of the dielectric substrate, and a second metal layer arranged on a second surface of the dielectric substrate, wherein the second surface is arranged opposite to the first surface along the thickness direction of the dielectric substrate; and the dielectric substrate is a curved panel. The embodiment of the application solves the problem that the filter cannot effectively utilize the narrow and curved surface space inside the satellite.

Description

Technical Field

[0001] This invention relates to the field of microstrip conformal filter technology, and more specifically, to a microstrip conformal low-pass filter and a satellite communication system. Background Technology

[0002] In existing technologies, traditional satellite communication systems primarily use waveguide cavity filters and rigid planar microstrip filters. However, these filters are inherently rigid planar structures, and are bulky and heavy. The internal environment of a satellite is complex, containing numerous non-planar structures, such as cylindrical fuel tanks, ring antenna supports, rocket fairing edges, and various cable conduits. Traditional filters can only be mounted on flat PCB boards and cannot conform to curved surfaces.

[0003] There is currently no effective solution to the aforementioned technical problems. Summary of the Invention

[0004] The main objective of this invention is to provide a microstrip conformal low-pass filter and a satellite communication system to solve the problem that filters in the prior art cannot effectively utilize the small, curved surface space inside a satellite.

[0005] To achieve the above objectives, according to one aspect of the present invention, a microstrip conformal low-pass filter is provided, comprising: a dielectric substrate; a first metal layer disposed on a first surface of the dielectric substrate; and a second metal layer disposed on a second surface of the dielectric substrate, wherein the second surface and the first surface are disposed opposite to each other along the thickness direction of the dielectric substrate; wherein the dielectric substrate is a curved panel.

[0006] Furthermore, the radius of curvature of the dielectric substrate is R1, where 19mm≤R1≤21mm.

[0007] Furthermore, the second metal layer forms the ground layer of the microstrip conformal low-pass filter, the first metal layer forms the surface layer of the microstrip conformal low-pass filter, and the first metal layer has multiple high and low impedance microstrip lines, which are arranged sequentially along the first direction, and adjacent high and low impedance microstrip lines are connected.

[0008] Furthermore, the aspect ratios of two adjacent high- and low-impedance microstrip lines are set differently, wherein the aspect ratio is the ratio of the length of the high- and low-impedance microstrip line in the second direction to the length of the high- and low-impedance microstrip line in the first direction, and the second direction is set perpendicular to the first direction.

[0009] Furthermore, the multiple high- and low-impedance microstrip lines include a first high- and low-impedance microstrip line, a second high- and low-impedance microstrip line, a third high- and low-impedance microstrip line, a fourth high- and low-impedance microstrip line, a fifth high- and low-impedance microstrip line, a sixth high- and low-impedance microstrip line, a seventh high- and low-impedance microstrip line, an eighth high- and low-impedance microstrip line, a ninth high- and low-impedance microstrip line, a tenth high- and low-impedance microstrip line, and an eleventh high- and low-impedance microstrip line arranged sequentially. The aspect ratio of the first high- and low-impedance microstrip line is 3.33 / 1.78, the aspect ratio of the second high- and low-impedance microstrip line is 0.8 / 6.5, and the aspect ratio of the third high- and low-impedance microstrip line is 1. The aspect ratios of the fourth high- and low-impedance microstrip line are 0.22 / 4.5, the fifth high- and low-impedance microstrip line is 1.02 / 9.73, the sixth high- and low-impedance microstrip line is 1.7 / 0.3, the seventh high- and low-impedance microstrip line is 2.2 / 4.47, the eighth high- and low-impedance microstrip line is 1.88 / 0.5, the ninth high- and low-impedance microstrip line is 0.37 / 5.18, the tenth high- and low-impedance microstrip line is 1.37 / 2.9, and the eleventh high- and low-impedance microstrip line is 0.74 / 1.78.

[0010] Furthermore, the center lines of multiple high and low impedance microstrip lines are arranged to coincide in the width direction.

[0011] Furthermore, the dielectric substrate is made of Rogers4350 material, which has a dielectric constant of 3.5 and a loss tangent of 0.0018.

[0012] Furthermore, the dielectric substrate has a length L and a width W, wherein 15mm≤L≤16mm, 14.5mm≤W≤15.5mm, and W≤L.

[0013] According to another aspect of the present invention, a satellite communication system is provided, the satellite communication system including a microstrip conformal low-pass filter, wherein the microstrip conformal low-pass filter is the microstrip conformal low-pass filter described above.

[0014] Furthermore, the satellite communication system also includes a cylindrical support structure, with a microstrip conformal low-pass filter wrapped around the outer periphery of the cylindrical support structure.

[0015] By applying the technical solution of this invention, the dielectric substrate is set as a curved panel. When the dielectric substrate is bent, the first metal layer and the second metal layer bend along with the dielectric substrate to form a complete conformal microstrip structure. This ensures that the boundary conditions of the electromagnetic field of the microstrip conformal low-pass filter are stable under the bending condition, and prevents poor grounding caused by deformation. The curved surface design allows the filter to perfectly fit the narrow and curved support structure inside the satellite, solving the problem that the filter cannot effectively utilize the narrow and curved surface space inside the satellite. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0017] Figure 1 A schematic diagram of a first embodiment of a microstrip conformal low-pass filter according to the present invention is shown;

[0018] Figure 2 A schematic diagram of a second embodiment of the microstrip conformal low-pass filter according to the present invention is shown;

[0019] Figure 3 A schematic diagram of simulation results for an embodiment of the microstrip conformal low-pass filter according to the present invention is shown.

[0020] The above figures include the following reference numerals:

[0021] 1. First metal layer; 2. Dielectric substrate; 3. Second metal layer;

[0022] 4. First high and low impedance microstrip line;

[0023] 5. Second high- and low-impedance microstrip lines;

[0024] 6. Third high- and low-impedance microstrip lines;

[0025] 7. Fourth high- and low-impedance microstrip line;

[0026] 8. Fifth high and low impedance microstrip line;

[0027] 9. The sixth high- and low-impedance microstrip line;

[0028] 10. The seventh high- and low-impedance microstrip line;

[0029] 11. The eighth high- and low-impedance microstrip line;

[0030] 12. Ninth high- and low-impedance microstrip line;

[0031] 13. The tenth high- and low-impedance microstrip line;

[0032] 14. Eleventh high and low impedance microstrip line. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "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.

[0036] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0037] In modern satellite communication systems, complex communication frequency bands introduce numerous harmonic interferences and spurious signals. To suppress these, low-pass filters are an indispensable component of the radio frequency front-end. Traditional satellite filters typically employ waveguide cavity structures or rigid planar microstrip circuits. However, this introduces a series of problems: First, there are issues with size and weight. Cavity filters offer the best performance but are large and heavy, occupying valuable payload resources within the satellite. Second, there are integration and space utilization issues. Traditional planar microstrip filters must be mounted on flat surfaces. However, satellites are filled with various curved structures, such as cylindrical fuel tanks, antenna masts, and the edges of rocket fairings. Planar devices cannot utilize these curved surfaces, resulting in wasted space within the satellite. Finally, there are physical challenges related to conformal design. Simply bending and bonding flexible circuit boards to curved surfaces, when the radius of curvature is small, causes a drift in the characteristic impedance of the conductors due to the physical deformation of the substrate and changes in the electromagnetic field boundary. This further leads to a shift in the filter's cutoff frequency, an increase in in-band insertion loss, and a decrease in out-of-band rejection capability.

[0038] Combination Figures 1 to 2 As shown, according to a specific embodiment of this application, a microstrip conformal low-pass filter is provided.

[0039] Specifically, the microstrip conformal low-pass filter includes a dielectric substrate 2, a first metal layer 1, and a second metal layer 3. The first metal layer 1 is disposed on a first surface of the dielectric substrate 2; the second metal layer 3 is disposed on a second surface of the dielectric substrate 2, and the second surface and the first surface are disposed opposite to each other along the thickness direction of the dielectric substrate 2; wherein, the dielectric substrate 2 is a curved panel.

[0040] The dielectric substrate 2 is the core carrier structure of the filter. The dielectric substrate 2 is a curved surface structure with a specific curvature. The first metal layer 1 is disposed on the first surface of the dielectric substrate 2, and the second metal layer 3 is disposed on the second surface of the dielectric substrate 2. The two metal layers are disposed opposite to each other along the thickness direction of the substrate.

[0041] By applying the technical solution of this embodiment, the dielectric substrate 2 is set as a curved panel. When the dielectric substrate 2 is bent, the first metal layer 1 and the second metal layer 3 bend along with the dielectric substrate 2 to form a complete conformal microstrip structure. This ensures that the boundary conditions of the electromagnetic field of the microstrip conformal low-pass filter are stable under the bending state, and prevents poor grounding caused by deformation. The curved surface design enables the filter to perfectly fit the narrow and curved support structure inside the satellite, solving the problem that the filter cannot effectively utilize the narrow and curved surface space inside the satellite.

[0042] Specifically, the radius of curvature of the dielectric substrate 2 is R1, where 19mm ≤ R1 ≤ 21mm.

[0043] In this embodiment, the radius of curvature of 19mm to 21mm precisely corresponds to the geometric features of common micro-cylindrical support structures on satellite platforms (such as antenna masts, cable conduits, or fuel tank edges). This avoids the problem that planar filters cannot fit such curved surfaces, often requiring additional mounting brackets that occupy valuable space and increase weight. By designing the radius of curvature of the dielectric substrate 2 between 19mm and 21mm, the filter can fit tightly against the surface of small structures. This not only eliminates the space occupied by additional mounting components and improves the utilization rate of the limited space inside the satellite, but also significantly reduces the overall size and weight of the device, effectively reducing launch costs.

[0044] It should be understood that when the radius of curvature is too small, the physical bending of the dielectric substrate 2 will cause a drastic shift in the characteristic impedance of the microstrip line, leading to severe impedance mismatch, increased insertion loss, cutoff frequency shift, and decreased out-of-band rejection capability. Conversely, when the radius of curvature is too large, it cannot accommodate a more compact spatial layout. By setting the radius of curvature in the range of 19mm to 21mm, the changes in the electromagnetic field boundary caused by bending can be effectively compensated.

[0045] In one exemplary embodiment of this application, the radius of curvature of the dielectric substrate 2 can be 19 mm, 19.3 mm, 20 mm, 20.5 mm, or 21 mm.

[0046] Specifically, the second metal layer 3 forms the ground layer of the microstrip conformal low-pass filter, the first metal layer 1 forms the surface layer of the microstrip conformal low-pass filter, and the first metal layer 1 has multiple high and low impedance microstrip lines. The multiple high and low impedance microstrip lines are arranged sequentially along the first direction, and adjacent high and low impedance microstrip lines are connected.

[0047] In this embodiment, multiple high and low impedance microstrip lines are formed in the first metal layer 1. These high and low impedance microstrip lines are slotted / strip structures with a certain width. The multiple high and low impedance lines are arranged in sequence to form a specific impedance transformer structure. By reasonably designing the characteristic impedance values ​​of the high and low impedance lines, the order of the filter is increased. This multi-section impedance matching structure has a wider impedance matching bandwidth and a flatter passband characteristic, thereby significantly reducing the insertion loss in the passband and ensuring efficient signal transmission.

[0048] Preferably, the aspect ratios of two adjacent high- and low-impedance microstrip lines are set differently, wherein the aspect ratio is the ratio of the length of the high- and low-impedance microstrip line in the second direction to the length of the high- and low-impedance microstrip line in the first direction, and the second direction is set perpendicular to the first direction.

[0049] In one exemplary embodiment of this application, such as Figure 1As shown, the x-direction is the first direction, which is the width direction of the dielectric substrate 2; the y-direction is the second direction, which is the length direction of the dielectric substrate 2; and the z-direction is the thickness direction of the dielectric substrate 2.

[0050] In this embodiment, by adjusting the aspect ratio of two adjacent high and low impedance microstrip lines, different aspect ratio combinations can optimize the coupling coefficient between each stage of the impedance transformer, reduce ripple in the passband, make the insertion loss in a specific passband more uniform and flat, and improve the quality of signal transmission.

[0051] By setting microstrip lines with different aspect ratios, the electromagnetic robustness to bending deformation is enhanced. Wider and shorter microstrip lines (low impedance) and narrower and longer microstrip lines (high impedance) exhibit different electromagnetic field distortion characteristics when bent. This difference can cancel each other out or partially compensate for each other in the overall structure, thereby maintaining the performance stability of the filter under bending conditions and preventing serious shift in the cutoff frequency.

[0052] Furthermore, the multiple high- and low-impedance microstrip lines include, sequentially arranged, a first high- and low-impedance microstrip line 4, a second high- and low-impedance microstrip line 5, a third high- and low-impedance microstrip line 6, a fourth high- and low-impedance microstrip line 7, a fifth high- and low-impedance microstrip line 8, a sixth high- and low-impedance microstrip line 9, a seventh high- and low-impedance microstrip line 10, an eighth high- and low-impedance microstrip line 11, a ninth high- and low-impedance microstrip line 12, a tenth high- and low-impedance microstrip line 13, and an eleventh high- and low-impedance microstrip line 14. The aspect ratio of the first high- and low-impedance microstrip line 4 is 3.33 / 1.78, the aspect ratio of the second high- and low-impedance microstrip line 5 is 0.8 / 6.5, and the aspect ratio of the third high- and low-impedance microstrip line 6 is... The aspect ratios of the fourth high-low impedance microstrip line 7 and 11 are as follows: 1.85 / 0.4; 0.22 / 4.5; 1.02 / 9.73; 1.7 / 0.3; 2.2 / 4.47; 1.88 / 0.5; 0.37 / 5.18; 1.37 / 2.9; and 0.74 / 1.78.

[0053] Each microstrip line has a specific length and width; the length determines the electrical length and resonant frequency, while the width determines the characteristic impedance. By setting up 11 microstrip lines with different aspect ratios, a complex impedance transformation network and resonant structure are constructed.

[0054] In this embodiment, the structure of multiple high- and low-impedance microstrip lines creates an extremely short transition band between the passband cutoff frequency (8.28 GHz, -3 dB) and the stopband suppression point (11.43 GHz, -40 dB), enabling faster attenuation of high-frequency signals and effectively filtering out high-order harmonic interference in X-band communication, ensuring spectral purity. Through precise parameter tuning, the reflection coefficients between each stage cancel each other out under bending conditions, maintaining an insertion loss as low as 1 dB within the 7 GHz passband and avoiding increased passband ripple or loss due to bending. By adjusting the specific aspect ratio of each line segment, the spacing and overlap between adjacent microstrip lines can be optimized, preventing unexpected resonance peaks in the stopband and ensuring a high suppression effect of 40 dB at 11.43 GHz.

[0055] Preferably, the center lines of the multiple high and low impedance microstrip lines are arranged to coincide in the width direction.

[0056] By aligning the centerlines of multiple high- and low-impedance microstrip lines in the width direction, the problem of asymmetrical electromagnetic field distribution caused by misalignment of the microstrip lines in the width direction is avoided, ensuring that the signal can still be transmitted stably along the predetermined path even when bent. When the centerlines of all microstrip lines in the width direction coincide, the entire filter structure maintains geometric symmetry in the width direction. This symmetry helps to maintain the pure transmission of the fundamental mode.

[0057] Specifically, the dielectric substrate 2 is made of Rogers 4350 material, which has a dielectric constant of 3.5 and a loss tangent of 0.0018.

[0058] Rogers 4350 is a widely used high-frequency laminate material in RF and microwave circuit design. Its main component is hydrocarbon resin, which has good flexibility. Rogers 4350 provides a moderate dielectric constant, which makes the filter more compact at the 7GHz operating frequency. The dielectric constant of 3.5 avoids the circuit being too crowded or the components being too large. It allows the filter to have 11 microstrip lines tightly arranged on a small curvature radius surface of 20mm, which is a perfect fit for the small satellite platform and greatly improves space utilization.

[0059] The loss tangent of 0.0018 results in low material loss, and the low loss tangent value means that very little energy is lost as electromagnetic waves propagate in the dielectric substrate and are converted into heat.

[0060] In this embodiment, by using Rogers 4350 material, the insertion loss at the 7GHz passband is only 1dB, which ensures that the power attenuation of the satellite communication signal is minimized when passing through the filter, thereby guaranteeing the signal-to-noise ratio at the receiver and the reliability of the communication link.

[0061] Specifically, the dielectric substrate 2 has a length L and a width W, wherein 15mm≤L≤16mm, 14.5mm≤W≤15.5mm, and W≤L.

[0062] In this embodiment, by setting the length of the dielectric substrate 2 within the range of 15mm to 16mm and the width within the range of 14.5mm to 15.5mm, miniaturization of the filter is achieved, greatly saving valuable payload space inside the satellite. This size range can match the common micro-cylindrical support structures inside satellites. When the dielectric substrate 2 is bent and fitted, its size ensures that the filter can be tightly wrapped around the slender support rods or conduits inside the satellite, avoiding loose fitting or suspension due to excessive size. At the same time, it ensures that when the dielectric substrate 2 is bent at a radius of curvature of 20mm, it will not crack or fail to fit due to excessive size, nor will it be too fragile due to excessive size.

[0063] In one exemplary embodiment of this application, L can be 15mm, 15.3mm, 15.48mm, or 16mm, and W can be 14.5mm, 14.8mm, 15mm, or 15.5mm.

[0064] According to another aspect of the present invention, a satellite communication system is provided, the satellite communication system including a microstrip conformal low-pass filter, wherein the microstrip conformal low-pass filter is the microstrip conformal low-pass filter described above.

[0065] By applying the technical solution of this embodiment, and setting the dielectric substrate 2 as a curved panel, when the dielectric substrate 2 bends, the first metal layer 1 and the second metal layer 3 bend along with the dielectric substrate 2, forming a complete conformal microstrip structure. This ensures the stability of the boundary conditions of the electromagnetic field of the microstrip conformal low-pass filter under curved conditions, preventing poor grounding caused by deformation. The curved surface design allows the filter to perfectly fit the narrow and curved support structure inside the satellite, solving the problem that the filter cannot effectively utilize the narrow and curved surface space inside the satellite. The microstrip conformal filter enables the integration of more functional modules within a limited satellite platform, improving the satellite's payload capacity and effectively extending its lifespan.

[0066] Specifically, the satellite communication system also includes a cylindrical support structure, with a microstrip conformal low-pass filter wrapped around the outer periphery of the cylindrical support structure.

[0067] The cylindrical support structure inside the satellite is a necessary component to maintain the structural strength of the satellite body. By wrapping the microstrip conformal filter around the outer circumference of the cylindrical support structure, the outer circumference of the cylindrical support structure is given radio frequency functionality. At the same time, it greatly frees up valuable space inside the satellite, allowing the satellite to carry more payloads and directly improving the satellite's payload ratio.

[0068] According to another specific embodiment of this application, a preferred embodiment of a large curvature conformal miniaturized microstrip low-pass filter applied to a satellite communication system is also provided.

[0069] Specifically, this embodiment belongs to the field of microwave passive devices and satellite communication, and specifically describes a large-curvature conformal miniaturized microstrip low-pass filter applied in satellite communication systems. This filter is particularly suitable for space-constrained satellite platforms, phased array antenna feed networks, and can conformally integrate with cylindrical support structures, such as satellite masts and cable conduits, into the RF front-end system.

[0070] Figure 1 This is a schematic diagram of the microstrip conformal low-pass filter structure in this embodiment. The dielectric substrate 2 used in this embodiment is made of Rogers 4350 (dielectric constant 3.5, loss tangent 0.0018), with a length of 15.48 mm and a width of 15 mm. The first metal layer 1 is the upper layer, etched with the pattern of the high- and low-impedance low-pass filter; the second metal layer 3 is the lower layer, serving as the ground plane of the filter. The radius of curvature of the entire structure is 20 mm.

[0071] Figure 2 The dimensions of each high- and low-impedance microstrip line are clearly labeled, indicating their specific size. From the first high- and low-impedance microstrip line 4 to the eleventh high- and low-impedance microstrip line 14, the length / width (in mm) of the microstrip lines are: 3.33 / 1.78, 0.8 / 6.5, 1.85 / 0.4, 0.22 / 4.5, 1.02 / 9.73, 1.7 / 0.3, 2.2 / 4.47, 1.88 / 0.5, 0.37 / 5.18, 1.37 / 2.9, and 0.74 / 1.78. These dimensional parameters ensure that the filter can be fabricated and implemented.

[0072] Figure 3 The simulation results for S21 (i.e., the ratio of the signal output from port 2 when the input signal is from port 1) of the microstrip conformal low-pass filter in this application show that the insertion loss at 7 GHz in the passband is only 1 dB, and the out-of-band rejection of up to 40 dB is achieved at 11.43 GHz in the stopband. This effectively filters out the interference of high-order harmonics in X-band communication.

[0073] To verify the effectiveness of the embodiments of this application, an embodiment of a microstrip conformal low-pass filter with a curvature radius of 20mm was designed.

[0074] like Figure 1 As shown, a Rogers 4350 flexible substrate was selected, with a thickness of 0.762 mm, a relative permittivity of 3.5, a loss tangent of 0.0018, a length of 15.48 mm, and a width of 15 mm. Figure 2 As shown, the filter is composed of 11 cascaded high and low impedance lines. Figure 3 The performance of the filter is shown, with an insertion loss of approximately 1 dB at 7 GHz and a -3 dB cutoff frequency at 8.28 GHz. At 11.43 GHz, an out-of-band rejection depth of 40 dB is achieved, resulting in a steep transition.

[0075] Specifically, regarding the conformal design method for small curvature radii, the core of this embodiment lies in using planar microstrip high and low impedance lines to achieve conformal integration between the substrate and a plane with a curvature radius of 20mm; and with a length of only 15.48mm, it achieves fast signal suppression from 8.28GHz (-3dB) to 11.43GHz (-40dB), which has significant advantages in miniaturized microstrip filters;

[0076] Specifically, this embodiment can be used in the arched structure of satellite communication to protect a radio frequency low-pass filter that is directly integrated into the surface of the satellite's cylindrical support structure, thus realizing the integration of the filter with the satellite's mechanical structure.

[0077] The core problem addressed in this embodiment is that traditional planar filters cannot utilize curved space, and their filtering performance is severely degraded due to bending effects at small radii of curvature.

[0078] The technical solution adopted in this embodiment solves the technical pain points of traditional technologies:

[0079] 1. Solves the problem that traditional planar filters cannot effectively utilize the limited and curved surface space inside satellites;

[0080] 2. Solve the problem of impedance mismatch and transmission characteristic degradation caused by bending effect in existing microstrip filters with extremely small radii of curvature;

[0081] 3. While maintaining high-performance out-of-band suppression, achieve device miniaturization to meet the application requirements of CubeSats.

[0082] The technical solution adopted in this embodiment has the following technical effects:

[0083] (1) In this embodiment, a planar microstrip low-pass filter was designed for a limit curvature radius of 20mm, which can be attached to the small support rod or duct of the satellite, greatly improving the utilization rate of the satellite's internal space;

[0084] (2) The planar low-pass filter designed in this embodiment still maintains excellent filtering characteristics under bending conditions. Simulation data shows that the insertion loss at 7 GHz in the passband is only 1 dB, and the out-of-band rejection at 11.43 GHz in the stopband is as high as 40 dB, which effectively filters out the interference of high-order harmonics in X-band communication;

[0085] (3) The total length of the planar low-pass filter designed in this embodiment is only 15.48 mm, and it is extremely lightweight, which hardly increases the launch cost of the satellite. It is very suitable for weight-sensitive CubeSats or low-Earth orbit constellation satellites.

[0086] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0087] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0088] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A microstrip conformal low-pass filter, characterized in that, include: Dielectric substrate (2); A first metal layer (1) is disposed on a first surface of the dielectric substrate (2); The second metal layer (3) is disposed on the second surface of the dielectric substrate (2), and the second surface and the first surface are disposed opposite to each other along the thickness direction of the dielectric substrate (2). The dielectric substrate (2) is a curved panel.

2. The microstrip conformal low-pass filter according to claim 1, characterized in that, The radius of curvature of the dielectric substrate (2) is R1, where 19mm≤R1≤21mm.

3. The microstrip conformal low-pass filter according to claim 1, characterized in that, The second metal layer (3) forms the ground layer of the microstrip conformal low-pass filter, and the first metal layer (1) forms the surface layer of the microstrip conformal low-pass filter. The first metal layer (1) has a plurality of high and low impedance microstrip lines, which are arranged sequentially along the first direction, and adjacent high and low impedance microstrip lines are connected.

4. The microstrip conformal low-pass filter according to claim 3, characterized in that, The aspect ratios of two adjacent high- and low-impedance microstrip lines are set differently, wherein the aspect ratio is the ratio of the length of the high- and low-impedance microstrip line in the second direction to the length of the high- and low-impedance microstrip line in the first direction, and the second direction is set perpendicular to the first direction.

5. The microstrip conformal low-pass filter according to claim 3, characterized in that, The plurality of high and low impedance microstrip lines include a first high and low impedance microstrip line (4), a second high and low impedance microstrip line (5), a third high and low impedance microstrip line (6), a fourth high and low impedance microstrip line (7), a fifth high and low impedance microstrip line (8), a sixth high and low impedance microstrip line (9), a seventh high and low impedance microstrip line (10), an eighth high and low impedance microstrip line (11), a ninth high and low impedance microstrip line (12), a tenth high and low impedance microstrip line (13), and an eleventh high and low impedance microstrip line (14) arranged sequentially. The aspect ratio of the first high and low impedance microstrip line (4) is 3.33 / 1.78, the aspect ratio of the second high and low impedance microstrip line (5) is 0.8 / 6.5, and the aspect ratio of the third high and low impedance microstrip line (6) is... The aspect ratios of the fourth high-low impedance microstrip line (7) and the fifth high-low impedance microstrip line (8) are 1.02 / 9.73, the sixth high-low impedance microstrip line (9) is 1.7 / 0.3, the seventh high-low impedance microstrip line (10) is 2.2 / 4.47, the eighth high-low impedance microstrip line (11) is 1.88 / 0.5, the ninth high-low impedance microstrip line (12) is 0.37 / 5.18, the tenth high-low impedance microstrip line (13) is 1.37 / 2.9, and the eleventh high-low impedance microstrip line (14) is 0.74 / 1.

78.

6. The microstrip conformal low-pass filter according to claim 3, characterized in that, The center lines of the multiple high and low impedance microstrip lines are arranged to coincide in the width direction.

7. The microstrip conformal low-pass filter according to claim 1, characterized in that, The dielectric substrate (2) is made of Rogers4350 material, which has a dielectric constant of 3.5 and a loss tangent of 0.0018.

8. The microstrip conformal low-pass filter according to claim 1, characterized in that, The dielectric substrate (2) has a length L and a width W, wherein 15mm≤L≤16mm, 14.5mm≤W≤15.5mm, and W≤L.

9. A satellite communication system, characterized in that, The satellite communication system includes a microstrip conformal low-pass filter, wherein the microstrip conformal low-pass filter is the microstrip conformal low-pass filter as described in any one of claims 1-8.

10. The satellite communication system according to claim 9, characterized in that, The satellite communication system also includes a cylindrical support structure, and the microstrip conformal low-pass filter is wrapped around the outer peripheral surface of the cylindrical support structure.

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