Broadband dielectric cap-shaped feed source and antenna

Abstract

The invention discloses a broadband dielectric cap-shaped feed source and antenna, the feed source comprises a shaped round waveguide tube and a dielectric cap, the shaped round waveguide tube is connected with the dielectric cap, the outer wall of the shaped round waveguide tube is provided with a multi-step shaped structure, and the dielectric cap is connected with the shaped structure. Each step forming structure in the multi-step forming structure is respectively used as a quarter-wavelength impedance converter for realizing broadband impedance matching of electromagnetic waves, and the dielectric cap is provided with a bending structure for performing collimation conversion on the direction of the electromagnetic waves. The bending structure comprises steps which are sequentially connected in the horizontal direction and used for achieving phase compensation of electromagnetic waves, and K / Ka wide-frequency-band high-performance work can be achieved.

Description

Technical Field

[0001] This invention relates to the field of antenna communication technology, specifically to a wideband dielectric cap-shaped feed and antenna. Background Technology

[0002] With the rapid development of global satellite communication technology, the demand for communication system capacity is showing a continuous upward trend. The diversified development of modern satellite communication applications has placed higher demands on the transmission efficiency and bandwidth performance of antenna systems.

[0003] As a key component of a parabolic antenna system, the feed source plays a crucial role in converting high-frequency current or waveguide-bound electromagnetic waves into free-space radiated electromagnetic waves. Its performance directly determines the antenna's gain efficiency, radiation pattern, and impedance matching characteristics, making it a core element in high-gain antenna design.

[0004] Among numerous feed technology solutions, the dielectric cap feed, with its unique structural characteristics, has become the preferred solution for small-aperture parabolic antennas. Its main advantages are as follows: In terms of structural design: the integrated dielectric molding technology is adopted, which greatly simplifies the complex assembly structure of traditional feed sources and reduces manufacturing difficulty and production costs.

[0005] Electrical performance: It has excellent radiation characteristics, ensuring that the antenna system achieves high aperture efficiency.

[0006] Integration level: Its compact structural design makes it particularly suitable for use in modern miniaturized communication devices, providing technical support for the miniaturization of terminal devices.

[0007] Currently, this type of feed has been widely used in satellite communications, radar systems and other fields, becoming an important technical path to improve the overall performance of small-aperture antenna systems.

[0008] Currently, conventional K / Ka band dielectric cap antennas have significant limitations in bandwidth performance. Specifically, the typical bandwidth for the receiving band is approximately 1.8 GHz, and the bandwidth for the transmitting band is approximately 1.6 GHz. This narrow-band characteristic severely restricts the antenna's application flexibility.

[0009] With the rapid development of satellite communication technology, antenna design is evolving towards broadband. The industry's requirements for antenna relative bandwidth are increasing, aiming to achieve full-band coverage for K / Ka satellite communication. An ideal broadband antenna needs to maintain stable key electrical performance indicators such as voltage standing wave ratio and radiation gain throughout the entire operating frequency band.

[0010] Existing cap-shaped feed technology faces multiple challenges in achieving wideband operation: impedance matching difficulty increases significantly with bandwidth expansion; phase center stability is difficult to guarantee over a wide bandwidth; and maintaining the consistency of radiation pattern faces technical bottlenecks.

[0011] There is a significant gap between the current state of technology and the needs of industry development, necessitating a breakthrough from traditional design approaches and the development of novel broadband cap-shaped feed technology solutions. This technological breakthrough will be of great significance in promoting the miniaturization and multi-functionality of satellite communication equipment. Summary of the Invention

[0012] To address these issues, this invention proposes a wideband dielectric cap-shaped feed and antenna.

[0013] According to one aspect of the present invention, a broadband dielectric cap-shaped feed source is proposed, comprising a shaped circular waveguide and a dielectric cap, wherein the shaped circular waveguide is connected to the dielectric cap, and the outer wall of the shaped circular waveguide is provided with a multi-level stepped shaped structure, wherein each level of the multi-level stepped shaped structure serves as a quarter-wavelength impedance transformer for achieving broadband impedance matching of electromagnetic waves, and the dielectric cap is provided with a bending structure for collimating the direction of electromagnetic waves, wherein the bending structure includes a series of steps connected in a horizontal direction for achieving phase compensation of electromagnetic waves.

[0014] Specifically, the radial and axial dimensions of each step in the multi-level stepped shaping structure are set to present a specific characteristic impedance at the corresponding center frequency point. The radial dimension is the sum of the binomial coefficient of the corresponding characteristic impedance sequence and the radial dimension compensation value, and the axial dimension is the sum of an integer multiple of a quarter of the guided wavelength at the corresponding center frequency point and the axial dimension compensation value.

[0015] Specifically, the multi-level stepped shaped structure includes at least four levels. The center frequency of the first level stepped shaped structure is 19 GHz, and the characteristic impedance is 116 Ω. The center frequency of the second level stepped shaped structure is 22.5 GHz, and the characteristic impedance is 114 Ω. The center frequency of the third level stepped shaped structure is 26 GHz, and the characteristic impedance is 196 Ω. The center frequency of the fourth level stepped shaped structure is 29.5 GHz, and the characteristic impedance is 337 Ω. The radial dimension compensation value ranges from 0.4 mm to 1.24 mm, and the axial dimension compensation value ranges from -3.77 mm to 0.6 mm.

[0016] Specifically, the first-level stepped shaping structure has a radial dimension of 16.10 mm and an axial dimension of 1.91 mm, the second-level stepped shaping structure has a radial dimension of 17.34 mm and an axial dimension of 5.78 mm, the third-level stepped shaping structure has a radial dimension of 21.30 mm and an axial dimension of 5.05 mm, and the fourth-level stepped shaping structure has a radial dimension of 19.60 mm and an axial dimension of 3.23 mm.

[0017] Specifically, it also includes a dielectric support assembly. The shaped circular waveguide and the dielectric cap are indirectly connected through the dielectric support assembly, which is made of cross-linked polystyrene. The lower part of the dielectric support assembly is tightly connected to the shaped circular waveguide, and the upper part of the dielectric support assembly is tightly connected to the dielectric cap. This curved surface and the shaped structure of the waveguide outer wall are designed synergistically in terms of electromagnetic performance, jointly optimizing the energy conversion efficiency from the waveguide to free space.

[0018] Specifically, the bending structure further includes a planar structure and a curved structure. The inner diameter of the planar structure is set to match the outer diameter of the upper part of the medium support component to achieve a tight connection between the upper part of the medium support component and the medium cap. The curvature of the curved structure is iteratively calculated based on the incident angle of the electromagnetic wave.

[0019] Specifically, the dielectric constant of each step is between that of air and the dielectric support component, with an initial value of one-quarter of the free-space wavelength of the center frequency of the electromagnetic wave. The thickness of each step is the sum of an integer multiple or fractional multiple of the initial value and the corresponding thickness compensation value. The length of each step is the sum of a fractional multiple of the initial value and the corresponding length compensation value.

[0020] Specifically, each level of the staircase includes at least eight steps, the initial value is 3.20mm, the thickness compensation value ranges from -0.31mm to 2.6mm, and the length compensation value ranges from -0.59mm to 0.55mm.

[0021] Specifically, the thickness of the first step is 0.19 mm and the length is 1.51 mm; the thickness of the second step is 1.39 mm and the length is 3.05 mm; the thickness of the third step is 3.27 mm and the length is 2.43 mm; the thickness of the fourth step is 0.16 mm and the length is 0.41 mm; the thickness of the fifth step is 0.84 mm and the length is 1.21 mm; the thickness of the sixth step is 0.10 mm and the length is 0.54 mm; the thickness of the seventh step is 0.10 mm and the length is 2.00 mm; and the thickness of the eighth step is 2.00 mm and the length is 0.64 mm.

[0022] According to one aspect of the invention, a wideband antenna is provided, comprising a wideband dielectric cap-shaped feed as described in any of the first aspects for transmitting / receiving antenna signals.

[0023] The advantages of this invention are: High-performance operation in the K / Ka wideband was achieved through a combined optimized design of the circular waveguide outer wall shaping structure, integrated dielectric support, and dielectric cap. The synergistic design of the waveguide outer wall shaping and dielectric cap effectively compensated for the phase dispersion effect during wideband operation, ensuring accurate beam pointing. The wideband characteristic allows tasks that previously required multiple narrowband antennas to be accomplished with a single antenna, significantly reducing the size and weight of the terminal equipment. Attached Figure Description

[0024] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0025] Figure 1 A schematic cross-sectional view of the overall structure of a broadband dielectric cap-shaped feed according to the present invention is shown; Figure 2 A schematic diagram of the shaped circular waveguide of a broadband dielectric cap-shaped feed according to the present invention is shown; Figure 3 A schematic diagram of the specific structure on the dielectric cap of a broadband dielectric cap-shaped feed according to the present invention is shown; Figure 4 A partially enlarged detail of the dielectric cap of a broadband dielectric cap-shaped feed according to the present invention is shown; Figure 5 A voltage standing wave ratio (VSWR) curve of a wideband dielectric cap-shaped feed according to the present invention in the K-band (receiving band) is shown. Figure 6 The diagram shows the voltage standing wave ratio (VSWR) curve of a broadband dielectric cap-shaped feed according to the present invention in the Ka band (transmission frequency band).

[0026] 100 - Shaped circular waveguide; 200 - Dielectric support assembly; 300 - Dielectric cap; 101 - First-level stepped shaped structure; 102 - Second-level stepped shaped structure; 103 - Third-level stepped shaped structure; 104 - Fourth-level stepped shaped structure; 301 - Planar structure; 302 - Curved surface structure; 303 - Each level of step; 3031 - First-level step; 3032 - Second-level step; 3033 - Third-level step; 3034 - Fourth-level step; 3035 - Fifth-level step; 3036 - Sixth-level step; 3037 - Seventh-level step; 3038 - Eighth-level step. Detailed Implementation

[0027] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] The fundamental reason for the narrow bandwidth of traditional dielectric cap feeds is that, at the bandwidth edges, a single dielectric cap structure cannot simultaneously solve both impedance mismatch and phase error problems. Therefore, the proposed solution first uses a wideband waveguide shaping structure to establish the impedance foundation (solving the matching problem), and then uses an optimized dielectric cap to shape the beam (solving the radiation problem). Iterative simulations are then used to achieve optimal matching between the two. This solution is based on the fact that the shape of the waveguide outer wall alters the electromagnetic field distribution near the waveguide opening, thus affecting the amplitude and phase of the field illuminating the dielectric cap; conversely, the presence of the dielectric cap also affects the impedance characteristics of the waveguide opening. Therefore, both must be treated as a holistic system for electromagnetic simulation and optimization. Optimizing either component alone cannot simultaneously achieve excellent impedance matching and radiation characteristics across such a wide bandwidth.

[0030] Figure 1A schematic cross-sectional view of the overall structure of a broadband dielectric cap-shaped feed is shown, including a shaped circular waveguide 100, a dielectric support assembly 200, and a dielectric cap 300. The shaped circular waveguide 100 and the dielectric cap 300 are indirectly connected through the dielectric support assembly 200. The lower part of the dielectric support assembly 200 is tightly connected to the shaped circular waveguide 100, and the upper part of the dielectric support assembly 200 is tightly connected to the dielectric cap 300. The outer wall of the shaped circular waveguide has a multi-level stepped shaped structure. Each level of the multi-level stepped shaped structure serves as a quarter-wavelength impedance transformer to achieve broadband impedance matching of electromagnetic waves. The dielectric cap has a bending structure for collimating the direction of electromagnetic waves. The bending structure includes a planar structure 301, a curved structure 302, and various steps 303 connected sequentially along the horizontal direction.

[0031] The propagation process of electromagnetic waves in this dielectric cap-shaped feed is as follows: The shaped circular waveguide 100 essentially constitutes a distributed impedance transformation network, asymptotically transitioning the waveguide impedance of the electromagnetic wave to free-space impedance through a stepped transition, overcoming the shortcomings of traditional designs that suffer from impedance abrupt changes over a wide bandwidth. When the electromagnetic wave reaches the waveguide opening of the shaped circular waveguide 100, it enters the dielectric support assembly 200 and illuminates the dielectric cap 300. The dielectric cap 300 collimates and transforms the wave, forming a radiation beam with excellent directionality. Throughout this process, the shaping of the waveguide outer wall and the dielectric cap-shaped antenna structure work together to ensure efficient transmission and radiation of broadband signals.

[0032] The shaped circular waveguide 100 serves as the basic transmission channel for the feed. This invention employs a special shaped structure design for the outer wall of the shaped circular waveguide 100. Instead of a traditional uniform cylindrical shape, the outer wall utilizes a multi-level stepped profile. This shaped structure, through precise control of the waveguide wall thickness variation, achieves impedance gradient matching over a wide bandwidth, effectively reducing reflection loss at different frequency points and thus significantly expanding the operating bandwidth.

[0033] The dielectric support assembly 200 is made of a low-loss dielectric material. In one optional embodiment, it employs a cross-linked polystyrene microwave plastic rod with a relative permittivity of approximately 2.53 and a loss tangent of less than or equal to 0.0005 over the operating frequency range. This low-loss characteristic is crucial for ensuring efficient transmission of electromagnetic waves.

[0034] The dielectric constant of each step 303 is between that of air and the dielectric support component 200. The dielectric support component 200 and the shaped structure of the shaped circular waveguide 100 are designed synergistically in terms of electromagnetic performance, jointly optimizing the energy conversion efficiency from the waveguide to free space. The core function of the dielectric cap 300 is to collimate the relatively divergent electromagnetic waves exiting the waveguide port of the shaped circular waveguide 100 into a more directional beam and illuminate the parabolic reflector. Its shape directly determines the phase distribution of the radiated wavefront, thereby affecting the antenna gain and sidelobe level.

[0035] The multi-stage stepped shaped structure on the shaped circular waveguide 100 is based on the theory of multi-stage stepped impedance transformers in microwave engineering. When electromagnetic waves propagate from the waveguide into free space, they are strongly reflected due to impedance abrupt changes. Traditional waveguides have a single-dimensional outer wall, and matching is only effective within a very narrow frequency band. To achieve good impedance matching over a wide frequency band (17.7-31 GHz), multi-stage impedance transformation is required.

[0036] like Figure 2 As shown, the multi-stage stepped shaped structure includes at least four stages, each of which (101, 102, 103, 104) is equivalent to a quarter-wavelength impedance transformer. By designing the radial (diameter) and axial (length) dimensions of each stage, it can be made to present a specific intermediate impedance value at the center frequency. These intermediate impedances form a smooth, gradual transition path between the waveguide impedance and the free-space impedance.

[0037] The radial dimension, i.e., the diameter of each step, determines the characteristic impedance of that step. The axial dimension, i.e., the length of each step in the wave propagation direction, is initially determined by the guided wave wavelength at the center frequency. The initial axial length of each step should be approximately an integer multiple of one-quarter of the guided wave wavelength at the corresponding center frequency. This length is crucial to ensuring that the step provides optimal impedance transformation near the center frequency. After determining the initial dimensions, to obtain the flattest or equirippled response within the target frequency band, thereby achieving an extremely low voltage standing wave ratio (VSWR) over a wide bandwidth, electromagnetic simulation software is used to parametrically scan the dimensions of each step and obtain the corresponding radial and axial dimension compensation values ​​to determine the final dimensions.

[0038] For the shaped circular waveguide 100, its characteristic impedance Z With diameter D Approximately proportional. The impedance transformation ratio of a multi-stage converter. R for: ; in Z space ≈377Ω Zwg This is the characteristic impedance calculated initially.

[0039] For a 4-stage transformation (N=4), its impedance sequence should satisfy: ; in Ci The coefficients are binomial coefficients. This represents the characteristic impedance at the input terminal. This represents the characteristic impedance of the first-stage stepped shaped structure. This represents the characteristic impedance of the second-level stepped shaped structure, and so on.

[0040] Table 1 Radial Dimensions of Shaped Circular Waveguide 100 ; The axial dimension is determined by the waveguide wavelength (λg), and the goal is to make each step equivalent to a transmission line of a quarter waveguide wavelength at the designed center frequency.

[0041] ; in, λ 0= c / f For free space wavelengths, fc The cutoff frequency of the TE11 mode in the shaped circular waveguide, f The center frequency designed for this step level.

[0042] Level 1 stepped shaped structure 101: biased towards low-frequency matching, taking... f 1 = 19.0 GHz; Level 2 step-shaping structure 102: Frequency selection f 2 = 22.5 GHz; Level 3 step-shaping structure 103: Frequency selection f 3 = 26.0 GHz; Level 4 step-shaped structure 104: biased towards high-frequency matching, taking... f 4 = 29.5 GHz.

[0043] Table 2. Axial dimension parameters of the shaped circular waveguide 100 ; The theoretical calculations (Htheory) here differ from the optimized values ​​because the theoretical formula applies to independent transmission lines, while in this case, the four steps are closely adjacent and strongly coupled. This coupling effect significantly alters the equivalent electrical length of each step.

[0044] As shown in Tables 1 and 2, the center frequency of the first-stage stepped shaped structure 101 is 19 GHz, and the characteristic impedance is 116 Ω; the center frequency of the second-stage stepped shaped structure 102 is 22.5 GHz, and the characteristic impedance is 114 Ω; the center frequency of the third-stage stepped shaped structure 103 is 26 GHz, and the characteristic impedance is 196 Ω; the center frequency of the fourth-stage stepped shaped structure 104 is 29.5 GHz, and the characteristic impedance is 337 Ω; the radial dimension compensation value ranges from 0.4 mm to 1.24 mm; and the axial dimension compensation value ranges from -3.77 mm to 0.6 mm. The first-level stepped shaping structure 101 has a radial dimension of 16.10 mm and an axial dimension of 1.91 mm. The second-level stepped shaping structure 102 has a radial dimension of 17.34 mm and an axial dimension of 5.78 mm. The third-level stepped shaping structure 103 has a radial dimension of 21.30 mm and an axial dimension of 5.05 mm. The fourth-level stepped shaping structure 104 has a radial dimension of 19.60 mm and an axial dimension of 3.23 mm.

[0045] like Figure 3 As shown, the planar structure 301, curved structure 302, and various steps 303 on the dielectric cap 300 are designed primarily based on the theory of electromagnetic wave radiation and antenna pattern synthesis. The specific bending structure of the dielectric cap (the contour defined by key points such as 301-303) acts as a phase corrector. When electromagnetic waves propagate in a medium, their wavelength shortens. By carefully designing the thickness and curvature variations of the dielectric cap 300, within the operating frequency band, spherical electromagnetic waves radiated from different positions on the cap can achieve nearly equal phase when reaching the parabolic surface, converting them into plane waves suitable for a parabolic antenna, thus achieving in-phase superposition and obtaining high gain. The curvature and position of the bending structures (301-303) were determined through electromagnetic simulation, repeatedly optimized with the goals of maximizing antenna gain, optimizing the radiation pattern, and stabilizing the phase center.

[0046] The initial inner diameter of the planar structure 301 is typically matched with the outer diameter of the underlying medium support component 200 to ensure a seamless physical connection. The curved structure 302 utilizes the formula for equal optical path length to iteratively calculate rays at different angles, determining the curved profile that optimally converts the spherical wavefront into a planar wavefront. Its design is based on the principle that all rays emanating from the point source (phase center) must experience equal optical path lengths (or phase changes) upon reaching the target reference surface after reflection from the curved surface to ensure wavefront in-phase operation. This is specifically calculated using the following formula: , Where, n medium Represents the refractive index of a dielectric material. It is related to the relative permittivity. The relationship is n = εr. in This represents the geometric path length of a ray propagating within a medium. air This represents the refractive index of air, approximately 1. out This represents the geometric path length of the ray propagating in air. It refers to the distance from the reflection point (curved structure 302) to the target reference surface (usually the aperture of a parabolic antenna). Φ(λ) represents the phase jump (unit: degrees) introduced by reflection. When a ray undergoes total or partial internal reflection at the medium-air interface, a phase change occurs, and this value is a function of the wavelength λ. λ represents the wavelength in free space. Constant: constant optical path. The total optical path of the central ray (axial ray) is usually taken as the reference reference.

[0047] The steps 303 connected sequentially along the horizontal direction form a specific shape for the dielectric cap 300, which can be regarded as a dielectric matching layer. According to transmission line theory, a layer with a dielectric constant between that of air and the main material of the dielectric cap, and a thickness that is an integer multiple or fractional multiple of one-quarter of the free-space wavelength of the center frequency of the electromagnetic wave, can reduce reflection.

[0048] The fundamental principle behind the horizontally connected stepped layers 303 is to precisely control the front phase by manipulating the path difference of electromagnetic waves on the reflecting surface, thereby converting divergent spherical waves into collimated plane waves and improving antenna gain and efficiency. When electromagnetic waves radiate from the end of the dielectric support assembly 200, they illuminate the inner surface of the dielectric cap 300. Because the distance from different positions on the reflecting surface to the phase center varies, the phase of the reflected wave also differs; direct reflection would lead to wavefront distortion. Each stepped layer 303 introduces an adjustable additional path difference through its uneven thickness to compensate for the phase, ensuring that the waves are as in-phase as possible on the aperture surface.

[0049] For the target wideband (17.7-31GHz), the center design frequency is taken as fc=23.41GHz, and its free space wavelength λ0=12.81mm.

[0050] For a step of thickness H, the electromagnetic wave reflection has a two-way path difference of 2H. This introduces a phase change. for: .

[0051] When H is positive (convex): the reflection path becomes shorter, which is equivalent to introducing a phase lead. When H is negative (groove): the reflection path becomes longer, which is equivalent to introducing a phase lag.

[0052] Therefore, the initial theoretical value of the step thickness H here is strongly correlated with a quarter of the free space wavelength: .

[0053] The length value L must be set in conjunction with the step thickness H. A specific H value requires a certain length to fulfill its phase compensation function, i.e., the range that the step is responsible for correcting. The initial value of L needs to match the H value to ensure sufficient space for phase transition in this region and to maintain the mechanical rationality of the structure. Based on engineering experience, the initial value of L is... Simple fractional multiples, such as (1 / 2, 1 / 4, 5 / 8).

[0054] Table 3. Parameters of each step 300 ; like Figure 4 As shown in Table 3, in a specific embodiment, the step-by-step steps include eight steps, the initial value is 3.20 mm, the thickness compensation value ranges from -0.31 mm to 2.6 mm, and the length compensation value ranges from -0.59 mm to 0.55 mm. The deviation of the parameters is fundamentally due to the fact that the initial value calculated based on the single-frequency phase compensation theory must undergo collaborative electromagnetic optimization aimed at the performance of the K / Ka full-band (17.7-31.0 GHz) system. This process dynamically balances the multi-band requirements, compensates for electromagnetic coupling and edge effects between structures, and transforms the idealized continuous phase surface into a discrete step-by-step phase quantization array with alternating positive and negative values ​​and varying depths.

[0055] Specifically, the thickness of the first step 3031 is 0.19 mm and the length is 1.51 mm; the thickness of the second step 3032 is 1.39 mm and the length is 3.05 mm; the thickness of the third step 3033 is 3.27 mm and the length is 2.43 mm; the thickness of the fourth step 3034 is 0.16 mm and the length is 0.41 mm; the thickness of the fifth step 3035 is 0.84 mm and the length is 1.21 mm; the thickness of the sixth step 3036 is 0.10 mm and the length is 0.54 mm; the thickness of the seventh step 3037 is 0.10 mm and the length is 2.00 mm; and the thickness of the eighth step 3038 is 2.00 mm and the length is 0.64 mm.

[0056] According to one aspect of the invention, a wideband antenna is provided, comprising a wideband dielectric cap-shaped feed as described in any of the first aspects for transmitting / receiving antenna signals.

[0057] Figure 5This is a voltage standing wave ratio (VSWR) curve of the feed of this invention in the K-band (receiving band). The horizontal axis represents frequency, ranging from 17.7 GHz to 21.2 GHz. The vertical axis represents the VSWR value. The red curve (VSWR) in the figure shows that the VSWR remains stable below 1.15 throughout the entire receiving band. This figure demonstrates that the present invention has excellent impedance matching characteristics in a wide bandwidth exceeding 3.5 GHz.

[0058] Figure 6 This is a voltage standing wave ratio (VSWR) curve of the feed source of this invention in the Ka band (transmitting frequency band). The horizontal axis represents frequency, ranging from 27.5 GHz to 31.0 GHz, and the vertical axis represents the VSWR value. The red curve (VSWR) in the figure shows that the highest VSWR value does not exceed 1.15 throughout the entire transmitting frequency band. This figure is consistent with... Figure 5 Together, they proved that the present invention can achieve stable wideband operation in both the K and Ka bands.

[0059] This technical solution effectively solves the core technical challenge of broadband feed design by innovatively combining the outer wall shaping of the circular waveguide with the dielectric cap structure, providing a feasible technical path for the development of high-performance satellite communication antennas.

[0060] Firstly, a significant bandwidth improvement was achieved. Through distributed impedance matching, the bandwidth was increased to K / Ka satellite communication wideband coverage, with K band: 17.7~21.2GHz; Ka band: 27.5~31.0GHz.

[0061] Secondly, based on the joint shaping design, this invention achieves multiple optimizations in radiation characteristics: Improved radiation pattern stability: The radiation pattern remains highly consistent across the entire operating frequency band.

[0062] Impedance matching optimization: Maintaining a voltage standing wave ratio (VSWR) below 1.3 over a wide bandwidth improves energy transfer efficiency.

[0063] Wide applicability: This solution is suitable for parabolic antennas of various sizes, and is particularly suitable for miniaturized satellite communication terminals.

[0064] Phase center stability: Through the coordinated design of waveguide outer wall shaping and dielectric cap, the phase dispersion effect of broadband operation is effectively compensated, ensuring the accuracy of beam pointing.

[0065] Miniaturization of devices: The wide bandwidth characteristic allows tasks that previously required multiple narrowband antennas to be completed to be accomplished with just a single antenna, significantly reducing the size and weight of terminal devices.

[0066] In summary, this invention achieves significant improvements in multiple dimensions such as bandwidth performance, impedance matching, and radiation characteristics through innovative joint shaping technology, providing reliable technical support for the development of satellite communication equipment and possessing significant engineering application value and market prospects.

[0067] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A broadband dielectric cap-shaped feed, characterized in that, The device includes a shaped circular waveguide and a dielectric cap. The shaped circular waveguide is connected to the dielectric cap. The outer wall of the shaped circular waveguide is provided with a multi-level stepped shaped structure. Each level of the multi-level stepped shaped structure serves as a quarter-wavelength impedance transformer to achieve broadband impedance matching of electromagnetic waves. The dielectric cap is provided with a bending structure to collimate the direction of electromagnetic waves. The bending structure includes steps connected sequentially along the horizontal direction to achieve phase compensation of electromagnetic waves.

2. The broadband dielectric cap-shaped feed according to claim 1, characterized in that, The radial and axial dimensions of each step in the multi-level stepped shaped structure are set to present a specific characteristic impedance at the corresponding center frequency point. The radial dimension is the sum of the binomial coefficient of the corresponding characteristic impedance sequence and the radial dimension compensation value, and the axial dimension is the sum of an integer multiple of a quarter of the guided wavelength at the corresponding center frequency point and the axial dimension compensation value.

3. A broadband dielectric cap-shaped feed according to claim 2, characterized in that, The multi-level stepped shaped structure includes at least four levels. The center frequency of the first level stepped shaped structure is 19 GHz, and the characteristic impedance is 116 Ω. The center frequency of the second level stepped shaped structure is 22.5 GHz, and the characteristic impedance is 114 Ω. The center frequency of the third level stepped shaped structure is 26 GHz, and the characteristic impedance is 196 Ω. The center frequency of the fourth level stepped shaped structure is 29.5 GHz, and the characteristic impedance is 337 Ω. The radial dimension compensation value ranges from 0.4 mm to 1.24 mm, and the axial dimension compensation value ranges from -3.77 mm to 0.6 mm.

4. A broadband dielectric cap-shaped feed according to claim 3, characterized in that, The first-level stepped shaping structure has a radial dimension of 16.10 mm and an axial dimension of 1.91 mm; the second-level stepped shaping structure has a radial dimension of 17.34 mm and an axial dimension of 5.78 mm; the third-level stepped shaping structure has a radial dimension of 21.30 mm and an axial dimension of 5.05 mm; and the fourth-level stepped shaping structure has a radial dimension of 19.60 mm and an axial dimension of 3.23 mm.

5. A broadband dielectric cap-shaped feed according to claim 1, characterized in that, It also includes a dielectric support assembly, through which the shaped circular waveguide and the dielectric cap are indirectly connected. The dielectric support assembly is made of cross-linked polystyrene, with the lower part of the dielectric support assembly tightly connected to the shaped circular waveguide and the upper part of the dielectric support assembly tightly connected to the dielectric cap.

6. A broadband dielectric cap-shaped feed according to claim 5, characterized in that, The bending structure also includes a planar structure and a curved structure. The inner diameter of the planar structure is set to match the outer diameter of the upper part of the medium support component to achieve a tight connection between the upper part of the medium support component and the medium cap. The curvature of the curved structure is iteratively calculated based on the incident angle of the electromagnetic wave.

7. A broadband dielectric cap-shaped feed according to claim 1, characterized in that, The dielectric constant of each step is between that of air and the dielectric support component, with an initial value of one-quarter of the free-space wavelength of the center frequency of the electromagnetic wave. The thickness of each step is the sum of an integer multiple or fractional multiple of the initial value and the corresponding thickness compensation value. The length of each step is the sum of a fractional multiple of the initial value and the corresponding length compensation value.

8. A broadband dielectric cap-shaped feed according to claim 7, characterized in that, The steps at each level include at least eight steps, the initial value is 3.20mm, the thickness compensation value ranges from -0.31mm to 2.6mm, and the length compensation value ranges from -0.59mm to 0.55mm.

9. A broadband dielectric cap-shaped feed according to claim 3, characterized in that, The thickness of the first step is 0.19 mm and the length is 1.51 mm; the thickness of the second step is 1.39 mm and the length is 3.05 mm; the thickness of the third step is 3.27 mm and the length is 2.43 mm; the thickness of the fourth step is 0.16 mm and the length is 0.41 mm; the thickness of the fifth step is 0.84 mm and the length is 1.21 mm; the thickness of the sixth step is 0.10 mm and the length is 0.54 mm; the thickness of the seventh step is 0.10 mm and the length is 2.00 mm; and the thickness of the eighth step is 2.00 mm and the length is 0.64 mm.

10. A broadband antenna, characterized in that, Includes a broadband dielectric cap-shaped feed as described in any one of claims 1 to 9 for transmitting / receiving antenna signals.

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