Circularly polarized radiator and circularly polarized antenna

Abstract

The present invention provides a circularly polarized radiator and a circularly polarized antenna, and relates to the technical field of circularly polarized antennas. The present invention proposes a circularly polarized radiator, which includes: an exponentially gradient metal ridge, a rectangular metal insert, a waveguide cavity metal base with a rectangular excitation slot, and a waveguide cavity metal wall; wherein the waveguide cavity metal wall is connected to the waveguide cavity metal base to form a waveguide air cavity with one side open, a pair of exponentially gradient metal ridges of the same size are distributed at diagonal positions on both sides of the waveguide air cavity, a plurality of laterally extended rectangular metal inserts are respectively inlaid on the exponentially gradient metal ridges, and a slender rectangular excitation slot is opened on the central axis of the waveguide cavity metal base. The circularly polarized radiator proposed by the present invention solves the problems of limited axial ratio bandwidth, large loss, and high cross-section of the current circularly polarized radiator, and can well adapt to the technical requirements of the platform for antenna payload.

Description

Technical Field

[0001] The present invention relates to the technical field of circularly polarized antennas, and in particular to a circularly polarized radiator and a circularly polarized antenna. Background Art

[0002] Circularly polarized antennas radiate circularly polarized electromagnetic waves. Compared to linearly polarized antennas, they offer numerous advantages, including improved communication quality, reduced Faraday rotation caused by the ionosphere, reduced polarization loss due to polarization mismatch, and greater flexibility in the relative positioning of transmitting and receiving antennas. These advantages make circularly polarized antennas highly attractive for many wireless systems, and they are widely used in space telemetry applications for satellites, space probes, and ballistic missiles.

[0003] At present, there are three ways to realize circular polarization antennas: First, realize circular polarization of the antenna itself in the radiation aperture by constructing a special antenna form, such as a cut-corner or cut-slot microstrip patch antenna and a four-arm spiral circularly polarized antenna. The former has a low profile and light weight but a narrow axial bandwidth, while the latter has a wide axial bandwidth but a high profile and a bulky structure; Second, introduce a circular polarization network to perform dual-point or four-point feeding of the radiation aperture, such as a 90° bridge or a multi-stage Wilkinson power divider network, to excite mutually orthogonal fields with a 90° difference in phase at the radiation aperture to achieve far-field circular polarization. This method has the advantages of a wide axial bandwidth, The polarization mode is flexible and adjustable, but the introduction of the circularly polarized network brings additional insertion loss, which greatly reduces the antenna efficiency; third, by loading a circularly polarized radiator, the fed linear polarized wave is twisted into a circularly polarized wave for radiation, such as loading a cut-angle patch circularly polarized radiator on the slot and loading a ridge waveguide circularly polarized radiator on the slot. Since this type of circularly polarized radiator is generally directly loaded on the radiation aperture surface, it has the advantages of low cross-section, low loss, and simple structure. However, the axial ratio bandwidth of the above two circularly polarized radiators is small, which seriously limits the application range of the antenna and the system performance.

[0004] In summary, the existing circularly polarized radiators cannot effectively solve the problems of limited axial ratio bandwidth, large loss, and high profile at the same time, and thus cannot adapt well to the platform's technical requirements for lightweight, low-profile, high-efficiency, and broadband antenna payloads. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the deficiencies in the prior art, the present invention provides a circularly polarized radiator and a circularly polarized antenna, which solve the problem that the existing circularly polarized radiator cannot simultaneously meet the requirements of ultra-wideband, low loss and low profile.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] In a first aspect, the present invention first proposes a circularly polarized radiator, comprising:

[0010] An exponentially graded metal ridge, a rectangular metal insert, a waveguide cavity metal base with a rectangular excitation gap, and a waveguide cavity metal wall;

[0011] The waveguide cavity metal wall includes two complete waveguide walls and two V-shaped gradually changing notched waveguide walls;

[0012] The waveguide cavity metal base, the two complete waveguide walls, and the two recessed waveguide walls together constitute a waveguide air cavity, and the two complete waveguide walls are the long sides of the waveguide air cavity, and the two recessed waveguide walls are the wide sides of the waveguide air cavity;

[0013] The long side of the rectangular excitation slot is parallel to the wide side of the waveguide air cavity;

[0014] Two identical exponentially graded metal ridges are arranged at symmetrical positions diagonally opposite to each other on both sides of the rectangular excitation slot, and are both located on the waveguide cavity metal base inside the waveguide air cavity, and the outer arc surfaces of the exponentially graded metal ridges are both oriented toward the center of the waveguide air cavity;

[0015] A plurality of rectangular metal inserts are embedded in the index-graded metal ridge and extend laterally along the upper surface of the waveguide cavity metal base.

[0016] Preferably, the vertical distance d1 of any point on the notch arc of the notch waveguide wall satisfies the exponential function:

[0017] d1=wa_a*exp(wa_k*h)+wa_l*h

[0018] Among them, wa_a, wa_k, and wa_l are the coefficients of the exponential function, which are determined by the low-frequency point of the operating frequency band.

[0019] Preferably, the vertical distance d of any point on the ridge arc of the exponentially gradient metal ridge satisfies the exponential function:

[0020] d=ri_a*exp(ri_k*h)+ri_l*h

[0021] Among them, ri_a, ri_k, and ri_l are the coefficients of the exponential function, which are determined by the degree of bandwidth expansion.

[0022] Preferably, the length of the rectangular excitation slot is less than λ / 2, and the width thereof is less than or equal to one tenth of the length; wherein λ is the free space wavelength of the low-frequency operating point.

[0023] Preferably, the rectangular metal insert includes a top rectangular metal insert, a middle first rectangular metal insert, a middle second rectangular metal insert, and a bottom rectangular metal insert, which are arranged in sequence from top to bottom.

[0024] Preferably, the long sides of the top rectangular metal insert extend toward the two recessed waveguide walls, and the wide sides extend toward the two complete waveguide walls; the long sides of the middle first rectangular metal insert, the middle second rectangular metal insert, and the bottom rectangular metal insert all extend toward the two complete waveguide walls, and the wide sides extend toward the two recessed waveguide walls.

[0025] Preferably, the waveguide cavity metal base, the two complete waveguide walls, and the two recessed waveguide walls together constitute the waveguide air cavity and are integrally processed from lightweight aluminum material.

[0026] Preferably, the metal base of the waveguide cavity, the complete waveguide wall, and the inner surface of the notched waveguide wall are all smoothed.

[0027] In a second aspect, the present invention further proposes a circularly polarized antenna, which includes a plurality of circularly polarized radiators as described above.

[0028] Preferably, a plurality of circularly polarized radiators are evenly arranged to form a radiation aperture of the circularly polarized antenna.

[0029] (3) Beneficial effects

[0030] The present invention provides a circularly polarized radiator and a circularly polarized antenna. Compared with the prior art, the present invention has the following advantages:

[0031] 1. The present invention proposes a circularly polarized radiator, comprising: an exponentially graded metal ridge, a rectangular metal insert, a waveguide cavity metal base with a rectangular excitation slot, and a waveguide cavity metal wall. The waveguide cavity metal wall and the waveguide cavity metal base are connected to form a waveguide air cavity with one side open. A pair of exponentially graded metal ridges of the same size are located at diagonally opposite positions on either side of the waveguide air cavity. A plurality of laterally extending rectangular metal inserts are embedded in the exponentially graded metal ridges. An elongated rectangular excitation slot is provided on the central axis of the waveguide cavity metal base. The circularly polarized radiator proposed by the present invention solves the problems of current circularly polarized radiators, such as limited axial ratio bandwidth, high loss, and high profile, and can well meet the platform's technical requirements for lightweight, low-profile, high-efficiency, and broadband antenna payloads.

[0032] 2. The circularly polarized radiator of this invention incorporates a pair of exponentially graded metal ridges at obliquely symmetrical positions within the waveguide air cavity. This guides the electromagnetic wave fed through the rectangular excitation slot to twist within the waveguide air cavity, forming orthogonal electric fields with equal amplitudes and a 90-degree phase difference at the radiating aperture, radiating circularly polarized waves. The discontinuities of the exponentially graded metal ridges excite multiple orthogonal fundamental modes with equal amplitudes and varying phase velocities. Compared to a single orthogonal fundamental mode, this reduces the phase flatness of the electromagnetic wave propagation path within the waveguide cavity and increases the antenna's axial ratio bandwidth.

[0033] 3. The circularly polarized radiator of the present invention is equipped with multiple metal inserts on the exponentially graded metal ridge, which expands the cutoff frequency of the waveguide, further reduces the phase difference flatness of the electromagnetic wave propagation path in the waveguide cavity, greatly improves the axial ratio bandwidth, and can fully cover the K and KA bands, achieving broadband operating characteristics.

[0034] 4. The circularly polarized radiator of the present invention introduces a "V"-shaped gradient notch waveguide wall. This structure destroys the field resonance state of the complete metal waveguide cavity side wall, resulting in the cutoff of high-order modes, so that the antenna operates in the fundamental mode state throughout the entire frequency band, and the antenna has good radiation performance in the high frequency band.

[0035] 5. The waveguide air cavity of the present invention is formed by integrated processing of all-metal materials, and has the advantages of large power capacity, high mechanical strength, excellent heat dissipation performance, no conductor loss and no dielectric loss. It is easy to achieve high radiation efficiency and high gain, and can be used as an array unit of a large phased array antenna. It is suitable for airborne and satellite-borne platforms with strict requirements on space weight and working environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic diagram of the overall structure of a circularly polarized radiator in an embodiment of the present invention;

[0038] Figure 2 is a perspective view of the overall structure of a circularly polarized radiator according to an embodiment of the present invention;

[0039] Figure 3 is a top view of a circularly polarized radiator according to an embodiment of the present invention;

[0040] Figure 4 is a side view of a circularly polarized radiator according to an embodiment of the present invention;

[0041] Figure 5 1 is a diagram showing the simulation results of the normal axis ratio of the circularly polarized radiator according to an embodiment of the present invention;

[0042] Figure 6 : This is the simulation result of the normalized H-plane far-field pattern of the circularly polarized radiator at low frequency in an embodiment of the present invention;

[0043] Figure 7 : This is the simulation result of the H-plane far-field normalized pattern of the circularly polarized radiator at the mid-frequency point in an embodiment of the present invention;

[0044] Figure 8 : This is the simulation result of the H-plane far-field normalized radiation pattern of the circularly polarized radiator at high frequency in an embodiment of the present invention;

[0045] In the figure, 1-waveguide air cavity; 2-exponential gradient metal ridge; 3-rectangular metal insert; 31-top rectangular metal insert; 32-middle first rectangular metal insert; 33-middle second rectangular metal insert; 34-bottom rectangular metal insert; 4-waveguide cavity metal base; 5-rectangular excitation gap; 6-waveguide cavity metal wall; 61-complete waveguide wall; 62-notched waveguide wall. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] The embodiments of the present application provide a circularly polarized radiator and a circularly polarized antenna, which solves the problem that existing circularly polarized radiators cannot simultaneously meet the requirements of ultra-wideband, low loss and low profile, and achieves the purpose of the antenna meeting the requirements of lightweight, low profile, high efficiency and broadband operation.

[0048] The technical solution in the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0049] To address the problem that existing circularly polarized radiators cannot simultaneously meet the requirements of ultra-wideband, low loss, and low profile, the technical solution of this application proposes an ultra-wideband, high-efficiency circularly polarized radiator, which includes: an exponentially graded metal ridge, a rectangular metal insert, a waveguide cavity metal base, a rectangular excitation slot, and a waveguide cavity metal wall. The waveguide cavity metal wall and the waveguide cavity metal base are connected to form an open waveguide air cavity. A pair of exponentially graded metal ridges of the same size are distributed diagonally on both sides of the waveguide air cavity. Each exponentially graded metal ridge is inlaid with four laterally extending rectangular metal inserts. A slender rectangular excitation slot is opened on the central axis of the waveguide cavity metal base. A pair of exponentially graded metal ridges guide the electromagnetic waves fed into the rectangular excitation slots to twist within the waveguide's air cavity, forming orthogonal electric fields with equal amplitudes and a 90-degree phase difference at the radiating aperture, generating circularly polarized waves. Multiple metal inserts placed on the exponentially graded metal ridges extend the waveguide's cutoff frequency, further reducing the phase flatness of the electromagnetic wave's propagation path within the waveguide cavity and significantly increasing the axial ratio bandwidth. The circularly polarized radiator proposed in this invention can effectively meet the platform's technical requirements for lightweight, low-profile, high-efficiency, and broadband antenna payloads.

[0050] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0051] Example 1:

[0052] In the first aspect, the present invention first proposes a circularly polarized radiator, see Figure 1-2 , the circularly polarized radiator comprises:

[0053] An exponentially graded metal ridge 2, a rectangular metal insert 3, a waveguide cavity metal base 4 with a rectangular excitation slit 5, and a waveguide cavity metal wall 6;

[0054] The waveguide cavity metal wall 6 includes two complete waveguide walls 61 and two V-shaped gradually changing notched waveguide walls 62;

[0055] The waveguide cavity metal base 4, the two complete waveguide walls 61, and the two recessed waveguide walls 62 together constitute the waveguide air cavity 1, and the two complete waveguide walls 61 are the long sides of the waveguide air cavity 1, and the two recessed waveguide walls 62 are the wide sides of the waveguide air cavity 1;

[0056] The long side of the rectangular excitation slot 5 is parallel to the wide side of the waveguide air cavity 1;

[0057] Two identical exponentially graded metal ridges 2 are arranged at symmetrical positions diagonally opposite to each other on both sides of the rectangular excitation gap 5, and are both located on the waveguide cavity metal base 4 inside the waveguide air cavity 1. At the same time, the outer arc surfaces of the exponentially graded metal ridges 2 are all facing the center of the waveguide air cavity 1; a plurality of rectangular metal inserts 3 are embedded in the exponentially graded metal ridges 2 and extend laterally along the upper surface of the waveguide cavity metal base 4.

[0058] As can be seen, the circularly polarized radiator proposed in this embodiment has a waveguide cavity metal wall connected to the waveguide cavity metal base to form an open-sided waveguide air cavity. A pair of exponentially graded metal ridges of equal size are distributed diagonally on either side of the waveguide air cavity. Multiple laterally extending rectangular metal inserts are inlaid on the exponentially graded metal ridges. A slender rectangular excitation slot is defined along the central axis of the waveguide cavity metal base. The circularly polarized radiator proposed in this invention solves the problems of limited axial ratio bandwidth, high loss, and high profile of current circularly polarized radiators. It can well meet the platform's technical requirements for lightweight, low-profile, high-efficiency, and broadband antenna payloads.

[0059] The following is combined with Figure 1-4 , as well as an explanation of the specific structure and its functions, to describe in detail the implementation process of an embodiment of the present invention.

[0060] like Figures 1 to 4 As shown, the circularly polarized radiator proposed in this embodiment includes: an index-graded metal ridge 2, a rectangular metal insert 3, a waveguide cavity metal base 4, a rectangular excitation slot 5, and a waveguide cavity metal wall 6.

[0061] The waveguide cavity metal wall 6 is connected to the waveguide cavity metal base 4 to form a waveguide air cavity 1 with an upward opening. This upward opening serves as the radiation aperture of the waveguide air cavity 1. The waveguide cavity metal wall 6 consists of two complete waveguide walls 61, symmetrically distributed about the center of the waveguide air cavity 1, and two notched waveguide walls 62 with a V-shaped gradient. The height of the highest point of the V-shaped gradient notched waveguide wall 62 is h. The vertical distance d1 of any point on the notched arc satisfies d1 = wa_a*exp(wa_k*h) + wa_l*h, where wa_a, wa_k, and wa_l are coefficients of the exponential function d1 = wa_a*exp(wa_k*h) + wa_l*h, determined by the low-frequency point of the operating band. In this embodiment, the operating frequency spans the K and KA frequency bands, and the low frequency is only 18 GHz. After optimization, wa_a = 0.04, wa_k = 0.57, and wa_l = 0.01. Then the vertical distance d1 of any point on the ridge arc satisfies d1 = 0.04*exp(0.57*h)+0.01*h.

[0062] In order to improve the low insertion loss characteristics of the entire waveguide air cavity 1, in this embodiment, a preferred method is, on the one hand, to smooth the inner surfaces of the waveguide cavity metal base 4 and the waveguide cavity metal wall 6; on the other hand, the entire waveguide air cavity 1 is made of lightweight aluminum material in an integrated manner.

[0063] In addition, the radiation aperture of the waveguide air cavity 1 is a rectangular radiation aperture or a square radiation aperture, and the aperture side length a is less than 3λ / 4, where λ is the free space wavelength of the low-frequency operating point. In this embodiment, considering that the circularly polarized radiator needs to cover a wider operating frequency band, a preferred method is to select the radiation aperture of the waveguide air cavity 1 as a rectangular radiation aperture during actual production, and set the aperture length (i.e., long side) a=12mm and the width (i.e., wide side) b=10mm. The wall thickness t of the waveguide cavity metal base 4 and the waveguide cavity metal wall 6 is 0.8mm, specifically as shown in FIG. Figure 3 shown.

[0064] A slender rectangular excitation slot 5 is defined along the central axis of the waveguide cavity's metal base 4. This slot serves as the feed port for the circularly polarized radiator. Its length is less than λ / 2, where λ is the free-space wavelength at the low-frequency operating point. Furthermore, the width of this rectangular excitation slot 5 should be significantly smaller than its length. Considering the engineering challenges involved, in actual production and fabrication, the width of the rectangular excitation slot 5 should be less than or equal to one-tenth of its length. In this embodiment, the length L0 of the rectangular excitation slot 5 is 9 mm, and the width W0 of the rectangular excitation slot 5 is 0.8 mm.

[0065] On the waveguide cavity metal base 4 in the waveguide air cavity 1, a pair of exponentially graded metal ridges 2 of identical shape and size are distributed, closely adhering to the upper surface of the waveguide cavity metal base 4 and the inner surface of the complete waveguide wall 61 of the waveguide cavity metal wall 6, and arranged at symmetrical positions diagonally opposite to each other on both sides of the rectangular excitation slot 5. For details, see Figure 1-4 The outer arc surfaces of the two exponentially graded metal ridges 2 face each other and face the inner center of the waveguide air cavity 1. Both exponentially graded metal ridges 2 are parallel to the long sides of the rectangular excitation slot 5. The exponentially graded metal ridges 2 are metal structures and are inlaid with multiple rectangular metal inserts 3 extending outward horizontally and parallel to the upper surface of the waveguide cavity metal base 4.

[0066] The height of the exponentially graded metal ridge 2 is the same as the height h of the complete waveguide wall 61 of the waveguide cavity metal wall 6. In this embodiment, h is 8 mm, and the distances from the two exponentially graded metal ridges 2 to the rectangular excitation slot 5 are the same, dk = 2 mm. The vertical distance d of any point on the ridge arc of the exponentially graded metal ridge 2 (i.e., the distance perpendicular to the complete waveguide wall 61) satisfies the exponential function d = ri_a * exp(ri_k * h) + ri_l * h, where ri_a, ri_k, and ri_l are the coefficients of the exponential function, which are determined by the degree of bandwidth expansion. In this embodiment, to achieve a bandwidth above the frequency doubling, after optimization, it is preferred that ri_a = 0.05, ri_k = 0.56, and ri_l = 0.02, so that the vertical distance d of any point on the ridge arc satisfies d = 0.05 * exp(0.56 * h) + 0.02 * h.

[0067] In this embodiment, four rectangular metal inserts 3 are provided, each of varying sizes, including, from top to bottom, a top rectangular metal insert 31, a middle first rectangular metal insert 32, a middle second rectangular metal insert 33, and a bottom rectangular metal insert 34. When these top rectangular metal inserts 31, 32, 33, and 34 are embedded in the exponentially graded metal ridge 2, the long sides of the top rectangular metal insert 31 extend toward the two V-shaped gradient recessed waveguide walls 62, and the wide sides extend toward the two complete waveguide walls 61. Meanwhile, the long sides of the middle first rectangular metal insert 32, the middle second rectangular metal insert 33, and the bottom rectangular metal insert 34 all extend toward the two complete waveguide walls 61, and the wide sides extend toward the two V-shaped gradient recessed waveguide walls 62. The length of the rectangular metal insert 3 also increases from top to bottom, and its width is optimized according to the required bandwidth and is generally no greater than a / 4, where a is the length of the radiation aperture of the waveguide air cavity 1. In this embodiment, the dimensions of the rectangular metal insert 3 from top to bottom are set as follows: length L1 = 1.9 mm, width W1 = 2.9 mm; length L2 = 3.6, width W2 = 1.2; length L3 = 4.3, width W3 = 1.8; length L4 = 4.4, width W4 = 2.9. Let the height difference between the second rectangular metal insert 33 in the middle layer and the rectangular metal insert 34 in the bottom layer be h c , then the height difference h between the middle first rectangular metal insert 32 and the middle second rectangular metal insert 33 is c2 =3*h c , the height difference h between the top rectangular metal insert 31 and the middle first rectangular metal insert 32 c3 =2*h c In this embodiment, h c =1mm, then h c2 =3mm,h c3 =2mm.

[0068] The working principle of the circularly polarized radiator proposed in this embodiment is as follows: an electromagnetic wave with an electric field direction perpendicular to the long side of the slot is fed into the rectangular excitation slot 5. After being perturbed by the index-graded metal ridge 2 inside the circularly polarized radiator, two mutually perpendicular TE10 and TE01 modes are generated. The physical parameters of the index-graded metal ridge 2, the rectangular metal insert 3, and the "V"-shaped gradient notch waveguide wall 62 are optimized so that the two mode components form an electric field with equal amplitude and a phase difference of 90 degrees within the widest possible operating frequency band, radiating to form a circularly polarized wave.

[0069] In addition, in order to verify the performance of the circularly polarized radiator proposed in this embodiment, we conducted simulation experiments on it. The simulation results are as follows: Figures 5 to 8 shown.

[0070] in, Figure 5 : This is a simulation result diagram of the normal axial ratio of the circularly polarized radiator in this embodiment. As can be seen from the figure, the axial ratio bandwidth of the circularly polarized radiator exceeds 2 times the frequency; Figure 6 : This is the simulation result of the H-plane far-field normalized pattern of the circularly polarized radiator at low frequency in this embodiment. As can be seen from the figure, the radiation performance is good at low frequency. Figure 7 : This is the simulation result of the H-plane far-field normalized pattern of the circularly polarized radiator at the intermediate frequency point in this embodiment. As can be seen from the figure, the radiation performance at the intermediate frequency point is good; Figure 8 : This is the simulation result of the H-plane far-field normalized pattern of the circularly polarized radiator at high frequencies in this embodiment. As can be seen from the figure, the radiation performance is good at high frequencies.

[0071] Based on the data in the above simulation experiment figures, it can be obtained that the frequency band in which the normal axis ratio of the circularly polarized radiator is less than 3dB is 18GHz~47GHz, which exceeds twice the frequency. It radiates left-handed circularly polarized waves in the far field and has good circular polarization performance in the upper half space.

[0072] Example 2:

[0073] In a second aspect, the present invention further provides a circularly polarized antenna, which includes a plurality of the circularly polarized radiators described above.

[0074] A circularly polarized antenna according to this embodiment includes several of the circularly polarized radiators described above. Specifically, the circularly polarized radiators are used as array elements in a large phased array circularly polarized antenna. Specifically, the radiation aperture of the circularly polarized antenna is formed by evenly arranging several of the circularly polarized radiators.

[0075] It is understandable that the circularly polarized antenna provided in the embodiment of the present invention corresponds to the above-mentioned circularly polarized radiator. The explanation, examples, beneficial effects, etc. of the relevant contents can refer to the corresponding contents in the circularly polarized radiator and will not be repeated here.

[0076] In summary, compared with the existing technology, the present invention has the following beneficial effects:

[0077] 1. The present invention proposes a circularly polarized radiator, comprising: an exponentially graded metal ridge, a rectangular metal insert, a waveguide cavity metal base with a rectangular excitation slot, and a waveguide cavity metal wall. The waveguide cavity metal wall and the waveguide cavity metal base are connected to form a waveguide air cavity with one side open. A pair of exponentially graded metal ridges of the same size are located at diagonally opposite positions on either side of the waveguide air cavity. A plurality of laterally extending rectangular metal inserts are embedded in the exponentially graded metal ridges. An elongated rectangular excitation slot is provided on the central axis of the waveguide cavity metal base. The circularly polarized radiator proposed by the present invention solves the problems of current circularly polarized radiators, such as limited axial ratio bandwidth, high loss, and high profile, and can well meet the platform's technical requirements for lightweight, low-profile, high-efficiency, and broadband antenna payloads.

[0078] 2. The circularly polarized radiator of this invention incorporates a pair of exponentially graded metal ridges at obliquely symmetrical positions within the waveguide air cavity. This guides the electromagnetic wave fed through the rectangular excitation slot to twist within the waveguide air cavity, forming orthogonal electric fields with equal amplitudes and a 90-degree phase difference at the radiating aperture, radiating circularly polarized waves. The discontinuities of the exponentially graded metal ridges excite multiple orthogonal fundamental modes with equal amplitudes and varying phase velocities. Compared to a single orthogonal fundamental mode, this reduces the phase flatness of the electromagnetic wave propagation path within the waveguide cavity and increases the antenna's axial ratio bandwidth.

[0079] 3. The circularly polarized radiator of the present invention is equipped with multiple metal inserts on the exponentially graded metal ridge, which expands the cutoff frequency of the waveguide, further reduces the phase difference flatness of the electromagnetic wave propagation path in the waveguide cavity, greatly improves the axial ratio bandwidth, and can fully cover the K and KA bands, achieving broadband operating characteristics.

[0080] 4. The circularly polarized radiator of the present invention introduces a "V"-shaped gradient notch waveguide wall. This structure destroys the field resonance state of the complete metal waveguide cavity side wall, resulting in the cutoff of high-order modes, so that the antenna operates in the fundamental mode state throughout the entire frequency band, and the antenna has good radiation performance in the high frequency band.

[0081] 5. The waveguide air cavity of the present invention is formed by integrated processing of all-metal materials, and has the advantages of large power capacity, high mechanical strength, excellent heat dissipation performance, no conductor loss and no dielectric loss. It is easy to achieve high radiation efficiency and high gain, and can be used as an array unit of a large phased array antenna. It is suitable for airborne and satellite-borne platforms with strict requirements on space weight and working environment.

[0082] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A circularly polarized radiator, characterized in that: The circularly polarized radiator comprises: An exponentially gradient metal ridge (2), a rectangular metal insert (3), a waveguide cavity metal base (4) with a rectangular excitation gap (5), and a waveguide cavity metal wall (6); The waveguide cavity metal wall (6) comprises two complete waveguide walls (61) and two V-shaped gradually changing notched waveguide walls (62); The waveguide cavity metal base (4), the two complete waveguide walls (61), and the two recessed waveguide walls (62) together constitute a waveguide air cavity (1), and the two complete waveguide walls (61) are the long sides of the waveguide air cavity (1), and the two recessed waveguide walls (62) are the wide sides of the waveguide air cavity (1); The long side of the rectangular excitation slot (5) is parallel to the wide side of the waveguide air cavity (1); Two identical exponentially gradient metal ridges (2) are arranged at symmetrical positions at diagonally opposite sides of the rectangular excitation gap (5), and are both located on the waveguide cavity metal base (4) inside the waveguide air cavity (1), and the outer arc surfaces of the exponentially gradient metal ridges (2) are both oriented toward the center of the waveguide air cavity (1); A plurality of rectangular metal inserts (3) are embedded in the exponentially gradient metal ridge (2) and extend laterally along the upper surface of the waveguide cavity metal base (4); The vertical distance d of any point on the ridge arc of the exponentially gradient metal ridge (2) satisfies the exponential function: d=ri_a*exp(ri_k*h)+ri_l*h Among them, ri_a, ri_k, and ri_l are the coefficients of the exponential function, which are determined by the degree of bandwidth expansion; The vertical distance d1 of any point on the notch arc of the notch waveguide wall (62) satisfies the exponential function: d1=wa_a*exp(wa_k*h)+wa_l*h Among them, wa_a, wa_k, and wa_l are the coefficients of the exponential function, which are determined by the low frequency point of the working band; The rectangular metal insert (3) comprises a top rectangular metal insert (31), a middle first rectangular metal insert (32), a middle second rectangular metal insert (33), and a bottom rectangular metal insert (34) which are arranged in sequence from top to bottom; The long sides of the top rectangular metal insert (31) extend toward the two notched waveguide walls (62), and the wide sides extend toward the two complete waveguide walls (61); the long sides of the middle first rectangular metal insert (32), the middle second rectangular metal insert (33), and the bottom rectangular metal insert (34) all extend toward the two complete waveguide walls (61), and the wide sides extend toward the two notched waveguide walls (62).

2. The circularly polarized radiator according to claim 1, wherein The length of the rectangular excitation slot (5) is less than λ / 2, and its width is less than or equal to one tenth of the length; wherein λ is the free space wavelength of the low-frequency operating point.

3. The circularly polarized radiator according to claim 1, wherein: The waveguide cavity metal base (4), the two complete waveguide walls (61), and the two recessed waveguide walls (62) together form the waveguide air cavity (1) and are integrally processed from a lightweight aluminum material.

4. The circularly polarized radiator according to claim 3, wherein: The inner surfaces of the waveguide cavity metal base (4), the complete waveguide wall (61), and the notched waveguide wall (62) are all smoothed.

5. A circularly polarized antenna, characterized in that: The circularly polarized antenna includes a plurality of circularly polarized radiators according to any one of claims 1 to 4.

6. The circularly polarized antenna according to claim 5, wherein: Several circularly polarized radiators are evenly arranged to form the radiation aperture of the circularly polarized antenna.

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