A multi-band shared-aperture satellite communication antenna feed network and a design method thereof

Abstract

This invention proposes a feed network and its design method for a multi-band common-aperture satellite communication antenna, relating to the field of satellite communication technology. This invention employs a three-dimensional heterogeneous layout, placing the low-frequency and high-frequency feed networks on the bottom and top layers of a multilayer dielectric substrate, with a shared ground layer in between. This effectively solves the problem of large space occupation in traditional discrete layouts. For the low-frequency network, characteristic mode theory guides the microstrip feeder design, and a stepped impedance transformer is loaded at the terminal, enabling good impedance matching for low-frequency signals across a wide bandwidth. For the high-frequency network, substrate-integrated waveguide technology is used to construct the signal transmission trunk and coupler gaps are set. Finally, a defective ground structure and a frequency-selective surface are simultaneously integrated on the shared ground layer through a single photolithography process. This allows the design to simultaneously achieve the dual functions of suppressing low-frequency leakage and transmitting high-frequency signals on the same physical layer.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and in particular to a feed network for a multi-band common-aperture satellite communication antenna and its design method. Background Technology

[0002] With the rapid development of satellite communication services, single frequency bands can no longer meet the demands for high-speed and high-capacity communication, making multi-band converged communication a growing trend. Common-aperture antennas, by integrating antenna elements from multiple frequency bands into the same physical aperture, effectively save space on satellite platforms, making them one of the preferred solutions for spaceborne antennas.

[0003] In multi-band common-aperture antenna design, the feed network is a key component for signal distribution and transmission. Since feed networks for different frequency bands need to operate simultaneously within the same physical aperture, their design faces the following technical challenges: First, strong mutual coupling effects exist between feed networks of different frequency bands, leading to decreased port isolation and affecting normal system operation; second, traditional multi-layer dielectric stacked structures are bulky, making it difficult to meet the miniaturization requirements of spaceborne equipment; and third, high-frequency signals suffer significant losses when passing through different dielectric layers, affecting antenna radiation efficiency.

[0004] To address the aforementioned problems, existing technologies typically improve isolation by adding shielding cavities or absorbing materials. However, this method increases volume and weight. Alternatively, different dielectric layers can be used to arrange the feed networks for each frequency band, but inter-layer coupling issues remain prominent. Therefore, this invention proposes a feed network and its design method for a multi-band common-aperture satellite communication antenna to solve the problems existing in the prior art. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to propose a power supply network for a multi-band common-aperture satellite communication antenna and its design method. The present invention can complete the overall design of a multi-band common-aperture antenna power supply network with a simple process, meet the design requirements of satellite communication systems for multi-band integrated power supply networks, and solve the problems existing in the prior art.

[0006] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a method for designing a feed network for a multi-band common-aperture satellite communication antenna, comprising the following steps: Step 1: Determine the frequency band group that the feeder network needs to cover based on the multi-band operation requirements of satellite communication. Then, place the low-frequency feeder network on the bottom layer of the multilayer dielectric substrate to form the primary feeder layer, and arrange the high-frequency feeder network on the top layer of the dielectric substrate to form the secondary feeder layer. Set up a common ground layer between the top and bottom layers. Step 2: For low-frequency feeder networks, characteristic mode theory is used to guide the design of microstrip feeders, and impedance transformation structures are loaded at the terminals of the microstrip feeders; Step 3: Construct a signal transmission trunk for the high-frequency feed network using substrate integrated waveguide technology, and set coupling gaps on the substrate integrated waveguide structure; Step 4: On the common stratum, a defective ground structure for suppressing low-frequency signal leakage and a frequency-selective surface for allowing high-frequency signals to pass through and suppressing low-frequency coupling are simultaneously formed using a patterning process. Step 5: Integrate the bottom layer, common ground layer and top layer into one unit through a multi-layer dielectric pressing process, and set the power supply port on the formed integrated body to complete the design of the power supply network.

[0007] A further improvement is that, in step one, the shared ground layer also serves as an electromagnetic isolation layer between the low-frequency feed network and the high-frequency feed network.

[0008] A further improvement is made in step two, where the impedance transformation structure is a stepped impedance transformer, and the electrical length of the stepped impedance transformer is set to one-quarter of the guide wavelength corresponding to the center frequency of the low-frequency band.

[0009] A further improvement is made in step three, where the coupling gap penetrates the top layer medium and the common ground layer, and the length of the coupling gap is set to half the wavelength corresponding to the center frequency of the high-frequency band.

[0010] A further improvement is that, in step four, the defective structure is composed of periodically arranged dumbbell-shaped units, and the frequency selection surface is composed of a periodically arranged I-shaped slot array.

[0011] A further improvement is that the dumbbell-shaped defect structure unit and the I-shaped slot array are simultaneously formed on a common layer through a single photolithography process.

[0012] A further improvement is that the opening direction of the dumbbell-shaped defect structure unit is perpendicular to the long side direction of the I-shaped gap.

[0013] A further improvement is that, in step three, the substrate integrated waveguide structure is formed by a periodic array of metallized vias on the top dielectric layer.

[0014] A multi-band common-aperture satellite communication antenna feed network, comprising: A multilayer dielectric substrate, the multilayer dielectric substrate comprising a bottom layer, a top layer, and a common ground layer located between the bottom layer and the top layer; A low-frequency microstrip feed network is arranged at the bottom layer, and the terminal of the low-frequency microstrip feed network is provided with an impedance transformation structure; A high-frequency substrate integrated waveguide feed network is arranged on the top layer, and the high-frequency substrate integrated waveguide feed network is provided with coupling gaps; The common ground layer integrates a defective ground structure and a frequency selective surface. The defective ground structure is used to suppress low-frequency mutual coupling and signal leakage, and the frequency selective surface is used to allow high-frequency signals to pass through while suppressing low-frequency coupling.

[0015] A further improvement is that the defect structure is a periodic dumbbell-shaped unit array, and the frequency selection surface is a periodic I-shaped slit array, both of which are formed simultaneously by a single photolithography step.

[0016] A further improvement is that the impedance transformation structure is a stepped impedance transformer with an electrical length that is one-quarter of the wavelength of the center frequency guide in the low-frequency band.

[0017] A further improvement is that the coupling gap penetrates the top layer and the common ground layer, and its length is half the wavelength of the center frequency of the high-frequency band.

[0018] The beneficial effects of this invention are as follows: This invention uses a three-dimensional heterogeneous layout to place the low-frequency and high-frequency feed networks on the bottom and top layers of a multilayer dielectric substrate, with a common ground layer in between. This allows the multi-frequency feed network to achieve high-density integrated design within a limited aperture, effectively solving the problem of large space occupation in traditional discrete layouts. Simultaneously, for the low-frequency network, characteristic mode theory guides the microstrip feed line design, and a stepped impedance transformer is loaded at the terminal, enabling good impedance matching design for low-frequency signals over a wide bandwidth. For the high-frequency network, substrate-integrated waveguide technology is used to construct the signal transmission trunk and coupler gaps are set, allowing high-frequency signals to complete the transmission path design in a low-loss manner. Finally, a defective ground structure and a frequency-selective surface are simultaneously integrated on the common ground layer through a single photolithography process. This allows the design to simultaneously achieve the dual functions of suppressing low-frequency leakage and transmitting high-frequency signals on the same physical layer, thus obtaining a high-isolation feed network design scheme without increasing the number of design layers or process complexity. Therefore, by adopting the design method of this invention, the overall design of a multi-band common aperture antenna feed network can be completed in a simple process, meeting the design requirements of satellite communication systems for multi-band integrated feed networks. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0020] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0021] Example 1 according to Figure 1As shown, this embodiment proposes a feeding network design method for a multi-band common-aperture satellite communication antenna, used to design a dual-band common-aperture antenna feeding network covering the L-band and Ka-band. The L-band is a low-frequency band with a center frequency of 1.6 GHz; the Ka-band is a high-frequency band with a center frequency of 30 GHz. The method includes the following steps: Step 1: Determine the frequency band group and plan the three-dimensional layout Based on the multi-band operational requirements of satellite communication, the frequency bands to be covered by the feed network are determined to be L-band and Ka-band. Rogers 5880 high-frequency laminate is selected as the multilayer dielectric substrate material, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The L-band feed network is placed on the bottom layer of the multilayer dielectric substrate, with a dielectric thickness of 1.5 mm, forming the primary feed layer. The Ka-band feed network is placed on the top layer of the dielectric substrate, with a dielectric thickness of 0.254 mm, forming the secondary feed layer. A common ground layer, consisting of a 0.035 mm thick copper foil layer, is placed between the top and bottom layers, serving as an electromagnetic isolation layer between the L-band and Ka-band feed networks. This three-dimensional heterogeneous layout separates the feed networks of the two frequency bands vertically, effectively reducing the overall footprint and achieving a miniaturized design.

[0022] Step 2: Design the L-band feeder network For L-band feeder networks, full-wave electromagnetic simulation software based on the method of moments (such as the eigenmode solver module in FEKO or HFS) is used to extract the eigenmodes within their radiation boundaries. Radiation boundary conditions are set during the solution process, and the eigenvalues ​​(λ) and mode importance coefficients (MS, ranging from 0 to 1) of the first six modes are extracted. The focus is on analyzing the characteristic current distribution corresponding to eigenmodes with MS values ​​close to 1, thereby determining the optimal layout of the microstrip feeder for efficient excitation of the target modes.

[0023] Based on the calculation results of characteristic mode theory, a microstrip feed line is etched on the surface of the underlying dielectric. In this embodiment, the width of the microstrip feed line is 4.8 mm, corresponding to a characteristic impedance of 50 Ω. A stepped impedance transformer is loaded at the end of the microstrip feed line as an impedance transformation structure. This stepped impedance transformer is composed of three microstrip lines of different widths connected in series. The widths of the three microstrip lines are 3.2 mm, 2.1 mm, and 4.8 mm, respectively, and the length of each is 12.5 mm. The 12.5 mm corresponds to one-quarter of the guide wavelength of the L-band center frequency (1.6 GHz). This one-quarter wavelength impedance transformation principle can gradually match the load impedance to the source impedance, thereby achieving broadband impedance matching of the L-band signal and reducing signal transmission loss.

[0024] Step 3: Design the Ka-band feeder network For Ka-band feed networks, substrate integrated waveguide (SIW) technology is used to construct the signal transmission trunk on the top layer of a dielectric substrate. Specifically, a periodic array of metallized vias is etched onto the surface of the top dielectric layer. The via diameter is 0.3 mm, and the spacing between adjacent vias is 0.5 mm, forming a substrate integrated waveguide structure with a width of 3.2 mm. The SIW structure combines the low-loss transmission characteristics of waveguides with the low profile advantages of microstrip lines, effectively reducing transmission loss of high-frequency signals.

[0025] A coupling slot is provided at one end of the formed substrate integrated waveguide structure. This coupling slot is rectangular, penetrating the top dielectric and the common ground layer, with a length of 5 mm and a width of 0.5 mm, for docking with the external waveguide port. The 5 mm corresponds to half the wavelength of the Ka-band center frequency (30 GHz). This half-wavelength slot serves as a resonant slot, enabling efficient energy coupling between the SIW and the external waveguide.

[0026] Step 4: Patterned Etching of Common Strata Patterning etching is performed on a common ground layer using a single photolithography process to simultaneously form a defect ground structure (DGS) to suppress low-frequency signal leakage and a frequency selective surface (FSS) to allow high-frequency signals to pass through while suppressing low-frequency coupling. This process requires only one mask and can complete the simultaneous formation of both structures in a single photolithography step, significantly simplifying the process compared to processing them separately.

[0027] The specific method for forming the defective ground structure is as follows: Periodically arranged dumbbell-shaped defective ground structure units are etched on the common ground layer, located around the periphery of the L-band microstrip feeder's orthogonal projection area. The working principle of DGS is that the dumbbell-shaped structure generates a parallel LC resonance effect at a specific frequency, forming band-stop characteristics, thereby suppressing low-frequency signal leakage and surface wave propagation. Each dumbbell-shaped unit consists of two rectangular holes and a connecting slit. The rectangular holes are 6mm long and 3mm wide, and the connecting slit is 2mm long and 0.5mm wide. According to the LC resonance approximation formula: f o = 1 / (2π√(LC)) The stopband center frequency can be controlled by adjusting the size parameters of the dumbbell. The center-to-center spacing of adjacent units is 10mm, and their periodic arrangement forms a distributed suppression of low-frequency signals.

[0028] The specific method for forming the frequency selective surface (FSS) is as follows: A periodically arranged array of I-shaped slots is etched into the non-metallized region of the Ka-band substrate integrated waveguide structure's orthogonal projection area on a common ground layer. The FSS operates by generating a bandpass response at its resonant frequency, allowing signals of that frequency to pass through while reflecting out-of-band signals. Each I-shaped slot consists of two parallel slots and one connecting slot. The two parallel slots are 2.5 mm long, 0.2 mm wide, and spaced 1.2 mm apart. The connecting slot is 1.2 mm long and 0.2 mm wide. The total electrical length of the I-shaped slots (approximately 2.5 mm + 1.2 mm ≈ 3.7 mm) is designed to be half the wavelength corresponding to 30 GHz, thus generating resonance at that frequency. The center-to-center spacing between adjacent units is 3 mm (less than the operating wavelength) to ensure the stability of the frequency selectivity of the periodic structure. The resonant frequency of this I-shaped slot array is set to the center frequency of the Ka-band feed network, 30 GHz, to allow Ka-band signals to pass through and suppress L-band coupling.

[0029] The aforementioned dumbbell-shaped defect structure unit and I-shaped slot array are simultaneously formed on a common ground layer using a single photolithography process, with the opening direction of the dumbbell-shaped defect structure unit perpendicular to the long side direction of the I-shaped slot. This orthogonal arrangement further reduces the electromagnetic coupling between the two structures, avoiding unnecessary mutual interference.

[0030] Step 5: Integration and Port Setup The bottom layer, common ground layer, and top layer are integrated into a single unit using a multi-layer dielectric lamination process. The lamination process parameters are: temperature 180℃, pressure 2.5MPa, and holding time 120min. An external waveguide port, a standard WR-28 waveguide interface, is provided on the side of the formed integrated unit and mates with the coupling slot set in step three. An SMA coaxial connector is provided on the bottom surface of the integrated unit and connects to the input end of the L-band microstrip feed line. The external waveguide port and the SMA coaxial connector are used as the input ends of the Ka-band feed network and the L-band feed network, respectively, thus completing the design of the feed network for a multi-band common-aperture satellite communication antenna covering the L-band and Ka-band.

[0031] Through steps one through five above, a multi-band common-aperture satellite communication antenna feed network is finally formed, the specific structure of which is as follows: The feed network comprises a multilayer dielectric substrate, which is integrated into a single unit consisting of a bottom layer, a top layer, and a common ground layer between the bottom and top layers via a multilayer dielectric lamination process. The low-frequency microstrip feed network located on the bottom layer is terminated with a stepped impedance transformer, the electrical length of which is one-quarter of the wavelength of the center frequency guide in the L-band. The high-frequency substrate-integrated waveguide feed network located on the top layer has a coupling slot that penetrates the top layer and the common ground layer, with a length half the wavelength of the center frequency in the Ka-band. A defective ground structure and a frequency selective surface are integrated on the common ground layer: the defective ground structure is a periodic dumbbell-shaped cell array used to suppress low-frequency mutual coupling and signal leakage; the frequency selective surface is a periodic I-shaped slot array used to allow high-frequency signals to pass through and suppress low-frequency coupling; both are simultaneously formed in different regions of the common ground layer using a single photolithography process, with the opening direction of the dumbbell-shaped cells perpendicular to the long side direction of the I-shaped slots. The integrated unit has an external waveguide port (WR-28) on its side that mates with the coupling slot, and an SMA coaxial connector on its bottom surface that connects to the microstrip feeder input.

[0032] Example 2 This embodiment provides a feeding network design method for a multi-band common-aperture satellite communication antenna, used to design a dual-band common-aperture antenna feeding network covering the S-band and Ku-band. The S-band is a low-frequency band with a center frequency of 2.5 GHz; the Ku-band is a high-frequency band with a center frequency of 15 GHz. The method includes the following steps: Step 1: Determine the frequency band group and plan the three-dimensional layout Based on the multi-band operational requirements of satellite communication, the frequency bands to be covered by the feed network are determined to be S-band and Ku-band. Taconic TLY-5 high-frequency laminate is selected as the multilayer dielectric substrate material, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The S-band feed network is placed on the bottom layer of the multilayer dielectric substrate, with a dielectric thickness of 2.0 mm, forming the primary feed layer. The Ku-band feed network is placed on the top layer of the dielectric substrate, with a dielectric thickness of 0.5 mm, forming the secondary feed layer. A common ground layer, consisting of a 0.035 mm thick copper foil layer, is placed between the top and bottom layers, serving as an electromagnetic isolation layer between the S-band and Ku-band feed networks.

[0033] Step 2: Design the S-band feeder network For the S-band feed network, the same characteristic mode analysis method as in Example 1 was used. Radiation boundary conditions were set in the electromagnetic simulation software, and the first six characteristic modes were extracted. The microstrip feeder layout was guided by the characteristic current distribution. A microstrip feeder with a width of 3.2 mm and a characteristic impedance of 50 Ω was etched onto the surface of the underlying dielectric. A stepped impedance transformer was loaded at the end of the microstrip feeder as an impedance transformation structure. This stepped impedance transformer consisted of two microstrip lines of different widths connected in series: 2.1 mm and 3.2 mm, both 9.5 mm long. The 9.5 mm length corresponds to one-quarter of the guide wavelength at the S-band center frequency (2.5 GHz), used to achieve broadband impedance matching for the S-band signal.

[0034] Step 3: Design the Ku-band feeder network For Ku-band feed networks, a substrate integrated waveguide (SIW) technology is used to construct the signal transmission trunk on the top layer of the dielectric substrate. Specifically, a periodic array of metallized vias is etched onto the surface of the top dielectric layer. The via diameter is 0.4 mm, and the spacing between adjacent vias is 0.6 mm, forming a substrate integrated waveguide structure with a width of 4.5 mm. A coupling slot is provided at one end of the formed substrate integrated waveguide structure. This coupling slot is rectangular, penetrating the top dielectric layer and the common ground layer, with a length of 8 mm and a width of 0.6 mm, for docking with an external waveguide port. The 8 mm corresponds to half the wavelength of the Ku-band center frequency (15 GHz).

[0035] Step 4: Patterned Etching of Common Strata Patterning etching is performed on the common ground layer using a single photolithography process, simultaneously forming a defect ground structure (DGS) to suppress low-frequency signal leakage and a frequency selective surface (FSS) to allow high-frequency signals to pass through while suppressing low-frequency coupling.

[0036] The specific method for forming the defective ground structure is as follows: On the common ground layer and at the periphery of the orthogonal projection area of ​​the S-band microstrip feeder, periodically arranged dumbbell-shaped defective ground structure units are etched. Each dumbbell-shaped unit consists of two rectangular holes and a connecting slit. The rectangular holes are 8 mm long and 4 mm wide, the connecting slit is 3 mm long and 0.6 mm wide, and the center-to-center distance between adjacent units is 12 mm.

[0037] The specific method for forming the frequency-selective surface is as follows: A periodically arranged array of I-shaped slots is etched into the non-metallized region of the Ku-band substrate integrated waveguide structure's orthogonal projection area on a common ground layer. Each I-shaped slot consists of two parallel slots and one connecting slot. The two parallel slots are 4 mm long, 0.3 mm wide, and 2 mm apart; the connecting slot is 2 mm long and 0.3 mm wide; and the center-to-center spacing between adjacent units is 5 mm. The resonant frequency of this I-shaped slot array is set to the center frequency of the Ku-band feed network, 15 GHz, to allow Ku-band signals to pass through and suppress S-band coupling.

[0038] The aforementioned dumbbell-shaped defect structure unit and I-shaped slot array are simultaneously formed on a common stratum using a single photolithography process, and the opening direction of the dumbbell-shaped defect structure unit is set to be perpendicular to the long side direction of the I-shaped slot.

[0039] Step 5: Integration and Port Setup The bottom layer, common ground layer, and top layer are integrated into a single unit using a multi-layer dielectric lamination process. The lamination process parameters are: temperature 175℃, pressure 2.2MPa, and holding time 100 minutes. An external waveguide port, a standard WR-62 waveguide interface, is provided on the side of the formed integrated unit, which mates with the coupling slot set in step three. An SMA coaxial connector is provided on the bottom surface of the integrated unit, connecting to the input end of the S-band microstrip feed line. The external waveguide port and the SMA coaxial connector serve as the input ends of the Ku-band feed network and the S-band feed network, respectively, thus completing the design of the feed network for a multi-band common-aperture satellite communication antenna covering both S-band and Ku-band frequencies.

[0040] The performance of the L / Ka dual-band feed network prepared in Example 1 was tested, and Comparative Example 1 was set up for comparison, as follows: Test conditions: The test was conducted at room temperature using a vector network analyzer. A full two-port calibration was performed prior to the test, covering the L-band (1.5GHz-1.7GHz) and Ka-band (29GHz-31GHz).

[0041] Comparative Example Setup: Comparative Example 1 uses the exact same substrate material (Rogers 5880), number of layers (three-layer structure: bottom layer, common ground layer, top layer), dielectric thickness (bottom layer 1.5mm, top layer 0.254mm), and the same L-band microstrip feeder layout and Ka-band substrate integrated waveguide layout as Example 1. The only difference is that the common ground layer in Comparative Example 1 is a complete copper foil layer without any patterned etching, i.e., it does not integrate dumbbell-shaped defect ground structure units and I-shaped slot arrays.

[0042] The test results are shown in the table below: As shown in the table above, compared with Comparative Example 1, the voltage standing wave ratios (VSWR) of both the L-band and Ka-band in Embodiment 1 of the present invention remain at a good level (L-band < 1.5, Ka-band < 1.6), indicating that the impedance matching performance of the two is comparable, and the present invention does not have a negative impact on its own matching. However, in terms of port isolation, the L-Ka port isolation of Embodiment 1 of the present invention reaches more than 35dB, while that of Comparative Example 1 is only about 23dB, an improvement of more than 12dB. This improvement is mainly attributed to the defective ground structure (DGS) and frequency selective surface (FSS) simultaneously integrated on the common ground layer in the present invention. The DGS effectively suppresses the surface wave propagation of low-frequency signals and leakage to the common ground layer by periodically etching the dumbbell-shaped cells around the orthographic projection area of ​​the microstrip feeder. The FSS, through the bandpass characteristics of the I-shaped slot array, allows the Ka-band signal to pass smoothly while reflecting the coupling energy of the L-band. The synergistic effect of the two significantly improves the mutual coupling problem between the two bands, thereby obtaining a feed network with high isolation.

[0043] Furthermore, this invention employs a three-dimensional heterogeneous layout with the low-frequency feed network at the bottom layer, the high-frequency feed network at the top layer, and a shared ground layer in between. This allows for tight vertical integration of the feed networks in both frequency bands, significantly reducing planar footprint compared to traditional discrete layouts and meeting the miniaturization requirements of spaceborne equipment. Regarding signal transmission loss, the L-band utilizes a microstrip feed line guided by characteristic mode theory, coupled with a quarter-wavelength stepped impedance transformer, achieving excellent broadband matching (VSWR < 1.5) and effectively reducing reflection loss. The Ka-band employs a substrate integrated waveguide (SIW) structure, combining the advantages of low-loss waveguide transmission and low-profile microstrip line integration, thus achieving low-loss transmission of high-frequency signals. Finally, on the shared ground layer, the DGS and FSS are simultaneously formed through a single photolithography process, requiring only one photomask. This eliminates the need for step-by-step processing or additional photolithography steps, simplifying the process and reducing manufacturing costs while improving isolation performance.

[0044] Thus, this invention simultaneously achieves multiple technical benefits such as high isolation, miniaturization, low loss, and simplified manufacturing process, and can meet the integration requirements of multi-band common-aperture satellite communication antennas for the power supply network.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its framework and scope of application, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing a feed network for a multi-band common-aperture satellite communication antenna, characterized in that: Includes the following steps: Step 1: Determine the frequency band group that the feeder network needs to cover based on the multi-band operation requirements of satellite communication. Then, place the low-frequency feeder network on the bottom layer of the multilayer dielectric substrate to form the primary feeder layer, and arrange the high-frequency feeder network on the top layer of the dielectric substrate to form the secondary feeder layer. Set up a common ground layer between the top and bottom layers. Step 2: For low-frequency feeder networks, characteristic mode theory is used to guide the design of microstrip feeders, and impedance transformation structures are loaded at the terminals of the microstrip feeders; Step 3: Construct a signal transmission trunk for the high-frequency feed network using substrate integrated waveguide technology, and set coupling gaps on the substrate integrated waveguide structure; Step 4: On the common stratum, a defective ground structure for suppressing low-frequency signal leakage and a frequency-selective surface for allowing high-frequency signals to pass through and suppressing low-frequency coupling are simultaneously formed using a patterning process. Step 5: Integrate the bottom layer, common ground layer and top layer into one unit through a multi-layer dielectric pressing process, and set the power supply port on the formed integrated body to complete the design of the power supply network.

2. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 1, characterized in that: In step one, the shared ground layer also serves as an electromagnetic isolation layer between the low-frequency feed network and the high-frequency feed network.

3. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 1, characterized in that: In step two, the impedance transformation structure is a stepped impedance transformer, and the electrical length of the stepped impedance transformer is set to one-quarter of the guide wavelength corresponding to the center frequency of the low-frequency band.

4. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 1, characterized in that: In step three, the coupling gap penetrates the top medium and the common ground layer, and the length of the coupling gap is set to half the wavelength corresponding to the center frequency of the high-frequency band.

5. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 1, characterized in that: In step four, the defective structure is composed of periodically arranged dumbbell-shaped units, and the frequency-selective surface is composed of a periodically arranged I-shaped slot array.

6. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 5, characterized in that: The dumbbell-shaped defect structure unit and the I-shaped slot array are simultaneously formed on a common stratum using a single photolithography process.

7. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 5, characterized in that: The opening direction of the dumbbell-shaped defect structure unit is perpendicular to the long side direction of the I-shaped slot.

8. The feeding network design method for a multi-band common-aperture satellite communication antenna according to claim 1, characterized in that: In step three, the substrate integrated waveguide structure is formed by a periodic array of metallized vias on the top dielectric.

9. A multi-band common-aperture satellite communication antenna feed network, characterized in that: include: A multilayer dielectric substrate, the multilayer dielectric substrate comprising a bottom layer, a top layer, and a common ground layer located between the bottom layer and the top layer; A low-frequency microstrip feed network is arranged at the bottom layer. The low-frequency microstrip feed network terminal is equipped with an impedance transformation structure. The impedance transformation structure is a stepped impedance transformer with an electrical length of one-quarter of the guide wavelength of the low-frequency center frequency. A high-frequency substrate integrated waveguide feed network is arranged on the top layer. The high-frequency substrate integrated waveguide feed network is provided with a coupling slot. The coupling slot penetrates the top layer and the common ground layer, and its length is half of the wavelength of the center frequency of the high-frequency band. The common ground layer integrates a defective ground structure and a frequency selective surface. The defective ground structure is used to suppress low-frequency mutual coupling and signal leakage, and the frequency selective surface is used to allow high-frequency signals to pass through while suppressing low-frequency coupling.

10. A multi-band common-aperture satellite communication antenna feed network according to claim 9, characterized in that: The defective structure is a periodic dumbbell-shaped unit array, and the frequency-selective surface is a periodic I-shaped slit array, both of which are formed simultaneously by a single photolithography process.

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