Ultra-wideband dielectric grating linear-to-circular polarization converter and circularly polarized antenna

Abstract

The application provides an ultra-wideband medium grating linear-circular polarization converter and a circular polarization antenna. The ultra-wideband medium grating linear-circular polarization converter comprises a plurality of medium grating plates arranged in parallel along a first direction, and each of the medium grating plates is embedded with an array of conductive cylinders; the axis of each conductive cylinder in the array of conductive cylinders is parallel to the first direction, and in each medium grating plate, the conductive cylinders in the array of conductive cylinders are distributed in a two-dimensional periodic array in a plane defined by a second direction and a direction of electromagnetic wave propagation, the second direction, the first direction and the direction of electromagnetic wave propagation are perpendicular to each other; along the first direction, the conductive cylinders in the adjacent two medium grating plates are arranged one by one and opposite to each other. The linear-circular polarization converter has the advantages of ultra-wide circular polarization bandwidth, low reflection, low insertion loss, simple structure and easy integrated manufacturing, and can be applied to wideband communication, radar and sensing system.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, specifically to an ultra-wideband dielectric grating line-circular polarization converter and a circular polarization antenna. Background Technology

[0002] Circular polarization (CP) antennas are insensitive to Faraday rotation and exhibit greater robustness against multipath fading and polarization mismatch. Therefore, they have been widely used in satellite and wireless communication systems. A common method to achieve circularly polarized radiation is to introduce an asymmetric structure into the radiator, thereby generating two orthogonal electromagnetic components with equal amplitude and a 90-degree phase difference. Another effective solution is to combine a linear polarization (LP) source with a circular polarizer to convert linearly polarized waves into circularly polarized waves. In recent years, circular polarizers have attracted considerable attention, as they can be used independently with various fed antennas or integrated with lenses to achieve high gain and beam scanning.

[0003] In existing designs, linear-circular polarization converters can be mainly divided into two categories: metallic frequency-selective surface (FSS) polarizers and dielectric grating linear polarizers. Metallic FSS structures typically rely on resonant units to achieve polarization conversion, resulting in narrow passbands and high insertion losses. Although multilayer frequency-selective surfaces can broaden the circular polarization bandwidth, they inevitably increase structural complexity, manufacturing costs, and transmission losses. In contrast, dielectric grating polarizers are typically composed of periodically arranged dielectric sheets. Due to their anisotropic response, the two orthogonal electric field components accumulate different phase delays during propagation, resulting in a phase difference of approximately 90° at the output. Since this phase delay is mainly generated by traveling wave propagation rather than by non-metallic resonance, dielectric grating polarizers typically have lower insertion losses and wider operating bandwidths.

[0004] However, typical anisotropic dielectric gratings exhibit near-dispersive characteristics, with the refractive index difference between two orthogonal polarizations remaining essentially constant with frequency. This leads to a linear increase in phase difference with frequency, thus limiting the achievable circular polarization operating bandwidth. In related research, the operating bandwidth of circularly polarized antennas based on dielectric photogates is typically still quite limited, around 30%. A wider operating bandwidth would help reduce the number of antennas, lower system costs, and simplify maintenance. Therefore, further expanding the operating bandwidth of linearly circularly polarized dielectric photogates has significant research value and broad application prospects. Summary of the Invention

[0005] In view of this, the present invention proposes an ultra-wideband dielectric grating line-circular polarization converter and a circular polarization antenna. Specifically, the present invention is achieved through the following technical solution:

[0006] According to a first aspect of the embodiments of this specification, an ultrawideband dielectric grating line-to-circular polarization converter is provided, comprising a plurality of dielectric grating plates arranged at intervals and parallel to each other along a first direction, wherein:

[0007] Each dielectric grating plate is embedded with a conductive cylindrical array;

[0008] The axis of each conductive cylinder in the conductive cylindrical array is parallel to the first direction, and the first direction is perpendicular to the electromagnetic wave propagation direction.

[0009] Within each dielectric grating plate, the conductive cylinders in the conductive cylinder array are arranged in a two-dimensional periodic array within a plane defined by the second direction and the electromagnetic wave propagation direction, wherein the second direction is perpendicular to the first direction and the electromagnetic wave propagation direction, respectively.

[0010] Along the first direction, the conductive cylinders in two adjacent dielectric grating plates are arranged in a one-to-one correspondence and facing each other.

[0011] According to a second aspect of the embodiments of this specification, a circularly polarized antenna is provided, comprising: a linearly polarized horn feed, a dielectric matching layer, and the ultra-wideband dielectric grating line-to-circular polarization converter described in the first aspect, wherein the dielectric matching layer is located between the linearly polarized horn feed and the ultra-wideband dielectric grating line-to-circular polarization converter;

[0012] The linearly polarized horn feed source is used to radiate linearly polarized electromagnetic waves;

[0013] The dielectric matching layer is used to achieve impedance matching between the linearly polarized horn feed and the ultra-wideband dielectric grating line-to-circular polarization converter.

[0014] The ultra-wideband dielectric grating line-to-circular polarization converter is used to convert the linearly polarized electromagnetic wave into a circularly polarized electromagnetic wave.

[0015] The embodiments of the present invention have at least the following technical effects:

[0016] (1) The present invention introduces a conductive cylindrical array into a dielectric grating line-circular polarization converter to construct a polarization-related structural dispersion response, so that the equivalent refractive index difference between the two orthogonal polarization components changes with frequency and the phase difference is maintained at around 90° in a wider frequency band, thereby expanding the axial ratio bandwidth.

[0017] (2) The dielectric grating line-circular polarization converter of the present invention has the advantages of low reflection, low insertion loss, simple structure and easy integrated manufacturing, and can be applied to broadband communication, radar and sensing systems. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Some specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings indicate the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0019] Figure 1 This is a schematic diagram illustrating the structure of an ultrawideband dielectric grating line-circular polarization converter according to an exemplary embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of a dielectric grating plate according to an exemplary embodiment of the present invention;

[0021] Figure 3 This is an equivalent circuit diagram illustrating an exemplary embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram illustrating the refractive index variation curve of a minimum polarization conversion unit as a function of frequency, as shown in an exemplary embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram illustrating the phase difference of a minimum unit as a function of frequency, as shown in an exemplary embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram showing a performance comparison between a conventional dielectric polarization gate and the dielectric polarization gate of the present invention, as illustrated in an exemplary embodiment of the present invention.

[0025] Figure 7 This is an exemplary embodiment of the present invention, showing the reflection coefficient and transmission coefficient curves of incident waves with different polarizations as a function of frequency.

[0026] Figure 8 This is a schematic diagram of the structure of a circularly polarized antenna shown in an exemplary embodiment of the present invention;

[0027] Figure 9 This is a schematic diagram illustrating the reflection coefficient and gain curve of a circularly polarized antenna according to an exemplary embodiment of the present invention;

[0028] Figure 10 This is a schematic diagram of the axial ratio curve of a circularly polarized antenna according to an exemplary embodiment of the present invention;

[0029] The markings in the figure are: 1-dielectric grating plate, 11-substrate, 12-conductive cylindrical array, 2-polarization conversion unit, 3-minimum unit, 31-dielectric block; 32-conductive cylinder, 5-ultra-wideband dielectric grating line-circular polarization converter, 51-mounting base, 6-dielectric matching layer, 7-speaker feed. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0032] To address the limitation of operating bandwidth in existing line-to-circular polarization converters, this invention embeds a conductive structure within a conventional dielectric photogater to maintain a phase difference of approximately 90° over a wider frequency band. The technical solution of this invention will be described in detail below with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic diagram illustrating the structure of an ultrawideband dielectric grating line-circular polarization converter according to an exemplary embodiment of the present invention, as shown below. Figure 1 As shown, the ultrawideband dielectric grating linear-circular polarization converter includes multiple dielectric grating plates 1 arranged at intervals and parallel to each other along a first direction, with air gaps formed between each dielectric grating plate 1. When a linearly polarized electromagnetic wave is incident along the electromagnetic wave propagation direction, the interval arrangement between the dielectric grating plates 1 causes the electromagnetic wave to be subjected to periodic dielectric perturbations, thereby generating anisotropic birefringence effect, accumulating different phase delays for the two orthogonal polarization components after the electromagnetic wave decomposition.

[0034] Each dielectric grating plate 1 is embedded with a conductive cylindrical array 12. In this embodiment, by embedding conductive cylinders in the dielectric grating plate 1, the dispersion limitation of the pure dielectric structure of the traditional linear-circular polarization converter can be overcome, and phase difference compensation between two orthogonal polarization components can be achieved in a wide bandwidth, providing a physical basis for realizing ultra-wideband linear-circular polarization conversion.

[0035] The axes of each conductive cylinder in the conductive cylindrical array 12 are parallel to the first direction, which is perpendicular to the electromagnetic wave propagation direction. This ensures that in the two orthogonal polarization components of the incident electromagnetic wave, the electric field direction of one component is parallel to the first direction, and the electric field direction of the other component is parallel to the electromagnetic wave propagation direction. This allows the two orthogonal polarization components to experience different electromagnetic responses during propagation, resulting in differentiated phase accumulation.

[0036] Within each dielectric grating plate 1, the conductive cylinders in the conductive cylinder array 12 are arranged in a two-dimensional periodic array within a plane defined by a second direction and the electromagnetic wave propagation direction, where the second direction is perpendicular to both the first direction and the electromagnetic wave propagation direction. This embodiment, by arranging the conductive cylinders at equal intervals in both the second direction and the electromagnetic wave propagation direction, forms a uniform and regular periodic structure on the surface of the dielectric grating plate 1. This ensures that the phase change of the electromagnetic wave remains consistent when passing through each periodic unit, thereby guaranteeing the stability and consistency of polarization conversion. Simultaneously, the periodic arrangement in the electromagnetic wave propagation direction creates a capacitive coupling effect between adjacent rows of conductive cylinders, while the periodic arrangement in the second direction ensures a uniform distribution of capacitive coupling between adjacent conductive cylinders within the same row, thus constructing an anisotropic dispersion response.

[0037] Along the first direction, the conductive cylinders in two adjacent dielectric grating plates 1 are arranged one-to-one and facing each other. Since an air gap is formed between adjacent dielectric grating plates 1, the conductive cylinders arranged on both sides of the air gap form a capacitive coupling structure, generating an equivalent capacitance effect during electromagnetic wave propagation. This capacitive coupling effect, together with the equivalent inductance effect generated by the induced current on the conductive cylinders, forms an LC-type dispersion response, causing the equivalent refractive index difference between the two orthogonal polarization components to gradually decrease with increasing frequency, thereby maintaining a phase difference of nearly 90° in the ultra-wideband and realizing ultra-wideband linear-circular polarization conversion.

[0038] In some embodiments, each dielectric grating plate is positioned along the electromagnetic wave propagation direction by... The grating is composed of sequentially arranged minimum units; each minimum unit includes a dielectric block and a conductive cylinder embedded within the dielectric block. The dielectric blocks of adjacent minimum units are interconnected to form the substrate of the dielectric grating. The conductive cylinders of adjacent minimum units are arranged at intervals along the direction of electromagnetic wave propagation. In this embodiment, the conductive cylinder is made of a conductive metal, such as copper.

[0039] like Figure 2As shown, each dielectric grating plate 1 is formed by polarization conversion units 2 arranged periodically along the second direction. The polarization conversion units 2 are formed by multiple minimum units 3 arranged periodically along the electromagnetic wave propagation direction. The phase difference produced by a single minimum unit 3 at the center frequency of the ultra-wideband dielectric grating line-circular polarization converter for the two orthogonal polarization components after the decomposition of the incident electromagnetic wave is: To achieve the conversion from linearly polarized to circularly polarized waves, the phase difference between the two orthogonal polarization components needs to reach π / 2 radians at the polarizer output. Therefore, the minimum number of units 3 required along the electromagnetic wave propagation direction... It should meet the following requirements:

[0040]

[0041] in, The phase difference generated by the smallest unit at the center frequency of the ultra-wideband dielectric grating line-circular polarization converter for the two orthogonal polarization components after the decomposition of the incident electromagnetic wave is when When the calculation result is not an integer, Round up.

[0042] For example, the smallest unit 3 includes a cuboid dielectric block 31 and a metal cylinder 32 embedded in the dielectric block 31, the axis of the metal cylinder 32 being parallel to the first side. The cuboid dielectric blocks in adjacent smallest units 3 are interconnected to form a complete substrate 11; the metal cylinders 32 in adjacent smallest units 3 are spaced apart from each other, thereby forming a periodic conductive cylinder array on the substrate 11.

[0043] Thus, the working principle of the ultra-wideband dielectric grating line-circular polarization converter in this embodiment is as follows:

[0044] For anisotropic dielectric polarizers, theory shows that the refractive index difference between the two orthogonal components must be inversely proportional to the frequency in order to maintain a stable phase difference over a wide bandwidth. When a linearly polarized electromagnetic wave is incident on the ultra-wideband dielectric grating linear-circular polarization converter of this invention, the incident electromagnetic wave is decomposed into a first polarization component and a second polarization component that are orthogonal to each other; wherein, the electric field direction of the first polarization component is parallel to the first direction, and the electric field direction of the second polarization component is parallel to the electromagnetic wave propagation direction.

[0045] like Figure 3 As shown, for the first polarization component The induced current on the conductive cylinder generates an equivalent inductance. The capacitive coupling between adjacent conductive cylinders generates an equivalent capacitance. Together, they form an LC-type dispersive response. For the second polarization component... Since the diameter of the conductive cylinder is much smaller than the operating wavelength, the inductive effect can be ignored. Only the equivalent capacitance generated by the capacitive coupling between adjacent conductive cylinders needs to be considered. . Figure 3 In the middle, The periodic interval of the dielectric grating plate, The thickness of the dielectric grating plate, is the propagation constant.

[0046] Based on the above equivalent circuit model, the equivalent refractive index of the ultrawideband dielectric grating-circular polarization converter in this embodiment can be obtained through the ABCD matrix:

[0047] ;

[0048] ;

[0049] in, and These represent the equivalent refractive indices of the smallest unit under the first polarization component and the second polarization component, respectively. and These represent the equivalent refractive indices of the smallest unit under the first and second polarization components, respectively, without the introduction of a metal cylinder. Free-space wave impedance; The speed of light in free space; The length of the smallest unit along the direction of electromagnetic wave propagation; Angular frequency; The equivalent inductance generated by the induced current in the conductive cylinder under the first polarization component incident; The equivalent capacitance formed by the coupling between adjacent metal cylinders under the first polarization component incident; The equivalent capacitance introduced by the second polarization component into the metal cylinder.

[0050] Through the above configuration, the introduction of the conductive cylindrical array causes the equivalent refractive index of the first polarization component to exhibit a dispersion characteristic that monotonically increases with frequency, while the equivalent refractive index of the second polarization component remains essentially constant with frequency. Therefore, the difference in equivalent refractive index between the two orthogonal polarization components gradually decreases with increasing frequency, effectively suppressing the linear change in phase difference with frequency. This allows the phase difference between the two orthogonal polarization components to remain stable over a wider frequency band, thereby achieving ultra-wideband linear-to-circular polarization conversion.

[0051] Specifically, such as Figure 4 As shown, compared with traditional dielectric polarization gratings, this invention, by embedding a conductive cylindrical array 12 within the dielectric grating plate 1, enables the equivalent refractive indices of the two orthogonal polarization components to exhibit distinctly different frequency response characteristics. Specifically, the equivalent refractive index of the first polarization component... The equivalent refractive index of the second polarization component increases monotonically with increasing frequency. It remains essentially unchanged as the frequency increases.

[0052] As can be seen from the frequency response characteristics of the equivalent refractive index described above, the equivalent refractive index difference between the two orthogonal polarization components gradually decreases with increasing frequency. Based on the relationship between phase difference and refractive index difference, the decrease in refractive index difference with frequency can effectively suppress the linear growth trend of phase difference with frequency, thereby avoiding the problem of limited circular polarization bandwidth caused by excessive linear increase in phase difference in traditional dielectric photogaters.

[0053] like Figure 5 As shown, the phase difference of a traditional dielectric polarization grating maintains an approximately linear relationship with frequency, and its phase difference increases monotonically with frequency. Therefore, it can only satisfy the 90° phase difference condition required for circular polarization conversion in a narrow frequency band near the center frequency, making it difficult to achieve wideband operation. However, this invention introduces a conductive cylindrical array 12 within the dielectric grating plate 1, causing the equivalent refractive index of the polarization grating structure to exhibit significant dispersion characteristics in the first direction, thereby changing the variation law of the phase difference between the two orthogonal polarization components with frequency.

[0054] In this invention, the phase difference between the two orthogonal polarization components no longer increases monotonically with frequency, but instead exhibits a trend of first increasing slowly and then decreasing slowly. Within a certain frequency band near the center frequency, the phase difference can be stably maintained at approximately 90°, thus satisfying the phase condition required for circular polarization radiation. These results demonstrate that by embedding a conductive cylindrical array 12 within the dielectric grating plate 1 and utilizing the dispersion characteristics of the conductive cylinders to differentially control the equivalent refractive index of the two orthogonal polarization components, this invention can effectively suppress the linear change of the phase difference with frequency, maintaining a stable phase difference over a wider frequency band, thereby significantly broadening the axial ratio bandwidth of the dielectric grating line-to-circular polarization converter.

[0055] Furthermore, this invention employs a structural scheme combining a dielectric grating and conductive cylinders, eliminating the need for multi-layer frequency selective surfaces or complex resonant structures, thus avoiding the problems of increased insertion loss and structural complexity. Simultaneously, the arrangement of the conductive cylindrical array 12 embedded in the dielectric grating plate 1 results in a polarizer with a compact structure, simple manufacturing process, and ease of integrated molding, making it widely applicable to the design of circularly polarized antennas in broadband communication, radar, and sensing systems.

[0056] In some embodiments, the axis of the conductive cylinder 32 in each minimum unit 3 passes through the geometric center of the dielectric block 31, that is, the conductive cylinder 32 is positioned at the exact center of the dielectric block 31. This ensures that the distribution of the dielectric material around the conductive cylinder 32 is symmetrical about the cylinder axis in the direction of electromagnetic wave propagation, making the dielectric disturbance experienced by the incident electromagnetic wave on both sides of the cylinder uniform. This symmetrical arrangement in this embodiment helps maintain the symmetry of the field distribution of the two orthogonal polarization components during propagation, avoiding additional phase distortion or polarization purity degradation introduced by cylinder eccentricity, thereby ensuring the stability and polarization purity of the linear-circular polarization conversion.

[0057] In some embodiments, the length of the conductive cylinder 32 along the first direction is equal to the thickness of the dielectric grating plate 1 along the first direction. That is, the conductive cylinder 32 completely penetrates the dielectric grating plate 1, and the two end faces of the conductive cylinder 32 are flush with the two surfaces of the dielectric grating plate 1, respectively.

[0058] In this embodiment, by setting the conductive cylinder 32 to be the same length as the dielectric grating plate 1, the conductive cylinder 32 can provide a continuous and complete induced current path for polarization components whose electric field direction is parallel to the axis of the conductive cylinder 32, thereby generating a definite equivalent inductance effect. Simultaneously, this setting also makes the boundary conditions at both ends of the conductive cylinder 32 clear and uniform, avoiding local electric field distortion or parasitic parameter uncertainties caused by the cylinder length being less than the plate thickness. This ensures the accuracy of the equivalent refractive index model established based on the ABCD matrix, providing a reliable physical basis for broadband phase difference design. Furthermore, in terms of manufacturing process, this structure can be achieved by opening through-holes in the dielectric grating plate 1 and filling the through-holes with conductive material, resulting in a simple and consistent process.

[0059] In some embodiments, all conductive cylinders 32 in the conductive cylindrical array 12 have the same diameter and the same length. By setting all conductive cylinders 32 to have the same diameter and length, it is ensured that the response of the conductive cylinders 32 to electromagnetic waves is consistent in each periodic unit of the dielectric grating plate 1, thereby forming a uniform periodic array structure. This embodiment ensures that the phase change of electromagnetic waves obtained when passing through each smallest unit 3 remains consistent, avoiding non-uniform phase errors introduced by the size differences of the conductive cylinders 32, and ensuring the stability and repeatability of polarization conversion performance. In addition, uniform size parameters also help reduce manufacturing difficulty and cost, and facilitate quality control and consistency inspection during mass production.

[0060] It is worth noting that the number of dielectric grating plates 1 arranged along the first direction is not less than 3, so as to form an effective grating periodic structure in the alternating arrangement of the dielectric grating plates and the air gap. The specific number of dielectric grating plates 1 can be adjusted according to the actual operating frequency band and design specifications.

[0061] In some embodiments, the substrate 11 of the dielectric grating plate 1 is made of polypropylene material.

[0062] For example, the substrate 11 is made of polypropylene material with a relative permittivity of 2.65 and a loss tangent of 0.0021. Along the electromagnetic wave propagation direction, each polarization conversion unit 2 includes 16 sequentially arranged minimum units 3 to meet the requirement of approximately 90° phase difference at the center frequency. The period of each minimum unit 3 along the electromagnetic wave propagation direction is 1.5 mm, therefore the total height of the ultra-wideband dielectric grating line-circular polarization converter along the electromagnetic wave propagation direction is 16 × 1.5 mm = 24 mm. Along the second direction, each dielectric grating plate 1 includes 17 periodically arranged polarization conversion units 2. Along the first direction, the ultra-wideband dielectric grating line-circular polarization converter is composed of 18 periodically arranged dielectric grating plates 1.

[0063] In this embodiment, when the electric field direction of the incident linearly polarized electromagnetic wave forms a 45° angle with both orthogonal polarization directions of the ultra-wideband dielectric grating linear-circular polarization converter, the incident electromagnetic wave is decomposed into a first polarization component and a second polarization component with equal amplitude and mutual orthogonality. For the first polarization component, the induced current on the conductive cylinder generates an equivalent inductance, and the capacitive coupling between adjacent conductive cylinders generates an equivalent capacitance. Together, they form an LC-type dispersion response, causing the equivalent refractive index of this polarization component to monotonically increase with frequency. For the second polarization component, since the diameter of the conductive cylinder is much smaller than the operating wavelength, the inductance effect can be ignored. Only the equivalent capacitance generated by the capacitive coupling between adjacent conductive cylinders is considered, and the equivalent refractive index of this polarization component remains essentially constant with frequency. Thus, the equivalent refractive index difference between the two orthogonal polarization components gradually decreases with increasing frequency, thereby maintaining a phase difference of nearly 90° over a wide frequency band and realizing ultra-wideband linear-circular polarization conversion.

[0064] To verify the technical effects of the present invention, three-dimensional full-wave electromagnetic simulation software was used to simulate and analyze the transmission performance and polarization conversion performance of the present invention.

[0065] Figure 6 The performance comparison results of a conventional dielectric polarization grating and the dielectric grating line-to-circular polarization converter of the present invention are shown. Figure 6 As shown, the phase difference of a traditional dielectric polarization gate increases approximately linearly with frequency, and can only satisfy the 90° phase difference condition required for circular polarization conversion in a relatively narrow frequency band near the center frequency. However, after introducing a conductive cylinder in this invention, the phase difference between the two orthogonal polarization components shows a trend of first slowly increasing and then slowly decreasing with frequency, and can be stably maintained at around 90° in a wider frequency range.

[0066] Specifically, the 3dB axial ratio bandwidth of a conventional dielectric polarization grating is 17.4GHz to 26.5GHz, with a relative bandwidth of approximately 41%; the 3dB axial ratio bandwidth of the ultra-wideband dielectric grating line-to-circular polarization converter of the present invention is 18.26GHz to 40.84GHz, with a relative bandwidth of approximately 76%, which is approximately twice that of the conventional solution.

[0067] The above results demonstrate that by embedding a conductive cylindrical array within the dielectric grating plate, the present invention can significantly broaden the axial ratio bandwidth of the dielectric grating line-to-circular polarization converter, achieving ultra-wideband line-to-circular polarization conversion performance.

[0068] Figure 7 The graphs showing the reflection and transmission coefficients of the ultra-wideband dielectric grating line-circular polarization converter of the present invention as a function of frequency for two orthogonally polarized incident waves are illustrated. Figure 7 As shown, the reflection coefficients of the two orthogonally polarized incident waves remain at a low level (below -10dB) within the operating frequency band, and the transmission coefficients are relatively close within the operating frequency band and are both below -1dB. This indicates that the ultra-wideband dielectric grating line-circular polarization converter of the present invention has good impedance matching characteristics and low insertion loss within the operating frequency band, and can efficiently convert incident linearly polarized electromagnetic waves into circularly polarized electromagnetic waves for output.

[0069] This invention also provides a circularly polarized antenna. For example... Figure 8 As shown, the circularly polarized antenna includes a horn feed 7, a dielectric matching layer 6, and an ultra-wideband dielectric grating line-circular polarization converter 5. The dielectric matching layer 6 is located between the horn feed 7 and the ultra-wideband dielectric grating line-circular polarization converter 5.

[0070] The horn feed 7 is used to radiate linearly polarized electromagnetic waves;

[0071] The dielectric matching layer 6 is used to achieve impedance matching between the horn feed 7 and the ultra-wideband dielectric grating line-circular polarization converter 5, so as to suppress electromagnetic reflection from the horn feed input to the ultra-wideband dielectric grating line-circular polarization converter 5 and reduce the impedance mismatch between the two.

[0072] The ultra-wideband dielectric grating line-to-circular polarization converter 5 is used to convert the linearly polarized electromagnetic wave into a circularly polarized electromagnetic wave.

[0073] In some embodiments, the circularly polarized antenna further includes a mounting base 51, which includes a base body that matches the ultra-wideband dielectric grating line-circular polarization converter 5 and a mounting fitting located on the periphery of the base body; the ultra-wideband dielectric grating line-circular polarization converter 5 is fixed to the base body; and the mounting fitting is fixedly connected to the dielectric matching layer and the external support structure.

[0074] For example, mounting fittings are provided around the base body. These mounting fittings can be mounting holes, which are connected to the dielectric matching layer and the external support structure through non-metallic fasteners, thereby ensuring the relative position stability between the dielectric photogater, the dielectric matching layer and the linearly polarized horn feed.

[0075] In this embodiment, the linearly polarized electric field direction of the horn feed 7 is at a 45° angle to both the first and second directions. The linearly polarized electromagnetic wave radiated by the horn feed is converted into a circularly polarized wave after passing through the ultra-wideband dielectric grating line-circular polarization converter 5.

[0076] Figure 9 The reflection coefficient and gain of the circularly polarized antenna constructed based on this invention are shown. This circularly polarized antenna exhibits a low reflection coefficient and relatively stable gain within its operating frequency band, demonstrating that this invention can maintain good impedance matching and radiation performance in practical antenna applications. Figure 10 The axial ratio results of the circularly polarized antenna constructed based on the present invention are shown. The measured 3dB axial ratio bandwidth of this circularly polarized antenna is 18.7 GHz to 38.2 GHz, with a relative bandwidth of approximately 68.5%, verifying that the present invention has ultra-wideband line-to-circular polarization conversion capability.

[0077] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather are primarily intended to describe features of specific embodiments of a particular invention. Certain features described in the various embodiments herein may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented separately in various embodiments or in any suitable sub-combination. Furthermore, while features may function in certain combinations as described above and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and a claimed combination may refer to a sub-combination or a variation thereof.

[0078] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0079] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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. An ultrawideband dielectric grating line-to-circular polarization converter, comprising a plurality of dielectric grating plates arranged at intervals and parallel to each other along a first direction, characterized in that: Each dielectric grating plate is embedded with a conductive cylindrical array; The axis of each conductive cylinder in the conductive cylindrical array is parallel to the first direction, and the first direction is perpendicular to the electromagnetic wave propagation direction. Within each dielectric grating plate, the conductive cylinders in the conductive cylinder array are arranged in a two-dimensional periodic array within a plane defined by the second direction and the electromagnetic wave propagation direction, wherein the second direction is perpendicular to the first direction and the electromagnetic wave propagation direction, respectively. Along the first direction, the conductive cylinders in two adjacent dielectric grating plates are arranged in a one-to-one correspondence and facing each other.

2. The ultra-wideband dielectric grating line-to-circular polarization converter according to claim 1, characterized in that: Each dielectric grating plate is along the direction of electromagnetic wave propagation. It consists of the smallest units arranged in sequence; The smallest unit includes a dielectric block and a conductive cylinder embedded in the dielectric block. The dielectric blocks of adjacent smallest units are connected to each other to form the substrate of the dielectric grating plate. The conductive cylinders of adjacent smallest units are arranged at intervals along the electromagnetic wave propagation direction. The satisfy: ； in, The phase difference generated by the smallest unit at the center frequency of the ultra-wideband dielectric grating line-circular polarization converter for the two orthogonal polarization components after the decomposition of the incident electromagnetic wave.

3. The ultra-wideband dielectric grating line-to-circular polarization converter according to claim 2, characterized in that, The axis of the conductive cylinder in the smallest unit passes through the geometric center of the dielectric block.

4. The ultra-wideband dielectric grating line-to-circular polarization converter according to claim 1, characterized in that, The length of the conductive cylinder along the first direction is equal to the thickness of the dielectric grating.

5. The ultra-wideband dielectric grating line-to-circular polarization converter according to claim 1, characterized in that, All conductive cylinders in the conductive cylinder array have the same diameter and the same length.

6. The ultra-wideband dielectric grating line-to-circular polarization converter according to claim 1, characterized in that, The substrate of the dielectric grating is made of polypropylene.

7. The ultra-wideband dielectric grating line-to-circular polarization converter according to any one of claims 1 to 6, characterized in that, The number of the plurality of dielectric gratings is not less than three.

8. A circularly polarized antenna, characterized in that, The invention includes a horn feed, a dielectric matching layer, and an ultrawideband dielectric grating line-circular polarization converter as described in any one of claims 1 to 7, wherein the dielectric matching layer is located between the horn feed and the ultrawideband dielectric grating line-circular polarization converter; The horn feed source is used to radiate linearly polarized electromagnetic waves; The dielectric matching layer is used to achieve impedance matching between the horn feed and the ultra-wideband dielectric grating line-circular polarization converter. The ultra-wideband dielectric grating line-to-circular polarization converter is used to convert the linearly polarized electromagnetic wave into a circularly polarized electromagnetic wave.

9. The circularly polarized antenna according to claim 8, characterized in that, It also includes a mounting base, which comprises a base body that matches the ultrawideband dielectric grating line-circular polarization converter and mounting fittings located around the base body; The ultra-wideband dielectric grating line-circular polarization converter is fixed to the base body; The mounting fitting is fixedly connected to the medium matching layer and the external support structure.

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