Satellite-borne Ka-band small compact broadband feed source

Abstract

The invention discloses a satellite-borne Ka-frequency-band small compact broadband feed source which comprises a radiation horn, a broadband circular polarizer, a non-equal octagonal waveguide, a broadband 45-degree polarization rotator, an orthogonal mode coupler, a left-handed output port and a right-handed output port. Broadband high-performance coverage work within 55% of working bandwidth is achieved, compact, small and broadband assemblies are utilized in the feed source assembly and comprise key assemblies such as a compact square-circle conversion assembly, a high-performance multi-degree-of-freedom broadband circular polarizer, a compact 45-degree polarization rotator and a compact broadband efficient orthogonal mode coupler, the whole feed source is more compact, and the size of the feed source is reduced. The antenna can be easily integrated with a reflector antenna; each key component of the feed source component is easy to process and controllable in precision, and can work in a Ka frequency band without debugging and a tuning column. The antenna has the advantages of being simple in structure, good in rigidity, high in reliability and the like while achieving the performance of wide frequency band, miniaturization, compactness, dual polarization and the like, and is used for tasks of inter-satellite communication and broadband signal receiving of satellites.

Description

Technical Field

[0001] This invention relates to the technical field of microwave antennas, and in particular to a small, compact, wideband satellite-borne Ka-band feed. Background Technology

[0002] With increasing demands for satellite communication capacity and the expansion and broadening of operating frequency bands for signal collection in radio astronomy, antennas typically require both a wide operating frequency band and high performance. This is especially true for achieving dual-channel dual-polarization while demanding good cross-polarization performance, pattern stability, high efficiency, and high gain. To achieve high gain, it is generally necessary to illuminate the reflector antenna using a feed source or to array the radiating elements using an array antenna. However, when achieving dual-channel dual-polarization, the feed network layout of the array antenna is complex; furthermore, in the Ka band, the insertion loss of the feed channels in the feed network is relatively large, often resulting in an array antenna failing to achieve a high-efficiency radiation pattern.

[0003] Generally, the core of achieving broadband operation using reflector-based antenna feeds lies in the performance of the feed source. Existing feed source implementations typically fall into the following categories:

[0004] One type is the Vivaldi antenna, which can operate within a bandwidth of 0.7-10.0 GHz, approximately 14.3 octaves. However, the main problem with this type of antenna is that its radiation pattern exhibits instability and poor consistency at different frequencies, with a half-angle cone-shaped illumination pattern. When used as a feed to illuminate a reflector, its radiation efficiency is low and varies greatly with frequency.

[0005] Another implementation is a dual-ridge or quad-ridge horn feed, which can operate from 2 to 6 GHz. However, similar to the Vivaldi antenna, the radiation pattern performance of the ridge horn antenna varies greatly with frequency, and its cross-polarization performance is generally poor. Furthermore, the aperture size of the ridge horn varies significantly with the ridge parameters, generally being larger. If a small-diameter reflector is illuminated (e.g., a 300mm aperture), the obstruction effect on the reflector is very significant. In addition, achieving dual circular polarization with the ridge horn requires components such as a bridge, which greatly increases transmission loss, system weight, and complexity.

[0006] To achieve high-performance radiation feeds, the typical implementation is a horn-type corrugated feed, which mainly consists of an orthogonal mode coupler, a circular polarizer (if circular polarization performance is required), a square-to-round transition, and a horn radiation port. Typical waveguide-type corrugated horns possess wide bandwidth characteristics, and their radiation pattern and phase center are insensitive to frequency changes. The key component for achieving high-performance dual-channel dual-polarization performance is the orthogonal mode coupler. However, typical orthogonal mode couplers either have insufficient bandwidth or excessive size. For example, the coupler disclosed in the patent application "A Broadband Waveguide Orthogonal Mode Coupler for Radio Astronomy Receivers Based on Turnstile Structure" (patent application number: CN202110267924.8) by Ning Yunwei et al., while exhibiting excellent operating bandwidth and performance, has excessively large dimensions for its four coupling arms, significantly increasing the size and weight of the feed and consequently the weight of the antenna feed system, making it unsuitable for spaceborne applications.

[0007] Therefore, the main problem with current spaceborne Ka-band small compact broadband feeds is that, under the conditions of requiring dual channels, dual polarization, high efficiency, low cross-polarization, and high gain (gain not less than 30dBi, reflector aperture not less than 300mm, operating bandwidth not less than 50%, and reflection coefficient < -25dB within the operating bandwidth):

[0008] a) Currently, existing feeds operate within a wide bandwidth, and their radiation pattern changes with frequency, resulting in unstable illumination performance.

[0009] b) The design and production of the feed source, especially the internal components of the feed source, often require debugging, testing, or installation of debugging columns.

[0010] c) Currently, the size of the common core component of the feed is too large, which in turn results in an oversized feed, causing severe obstruction of the reflective surface and low efficiency. Summary of the Invention

[0011] This invention provides a small, compact, wideband satellite Ka-band feed source, which can be mass-produced to meet the mission requirements of inter-satellite communication and reception.

[0012] In the first aspect, a small, compact, wideband feed for Ka-band on a spaceborne device is provided, including a radiating horn, a broadband circular polarizer, an asymmetrical octagonal waveguide, a broadband 45° polarization rotator, an orthogonal mode coupler, a left-hand rotary output port, and a right-hand rotary output port.

[0013] The radiating horn includes a choked corrugated horn, a transmission circular waveguide, a waveguide transformer, and an output tapered section. The choked corrugated horn and the output tapered section are located on one side of the transmission circular waveguide, and the waveguide transformer is located on the other side. The transmission circular waveguide is a hollow cylinder. The inner wall of the output tapered section is conical, and the outer wall is cylindrical. The first end of the output tapered section is directly connected to the transmission circular waveguide, and the inner diameter of the first end of the output tapered section is the same as that of the transmission circular waveguide. The inner diameter of the second end of the output tapered section is larger than that of the transmission circular waveguide. The choked corrugated horn is located on the periphery of the output tapered section to form an annular groove on the outer side of the output tapered section. The waveguide transformer is an internal cavity structure located at the flange end of the radiating horn, used to connect a broadband circular polarizer. Along the path from the radiating horn to the broadband circular waveguide... The polarizer is oriented with waveguide transformations consisting of a circular waveguide segment, a first octagonal waveguide segment, and a second octagonal waveguide segment. The circular waveguide segment is connected to the transmission circular waveguide and is hollow cylindrical. The first octagonal waveguide segment connects the circular waveguide segment and the second octagonal waveguide segment, forming a hollow, symmetrical, octagonal cross-section. The second octagonal waveguide segment also has a hollow, symmetrical, octagonal cross-section. The first and second octagonal waveguide segments have different structural dimensions. The faces containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment. The faces containing the 2nd, 4th, 6th, and 8th sides of the second octagonal waveguide segment are parallel to the faces containing the 2nd, 4th, 6th, and 8th sides of the first octagonal waveguide segment.

[0014] The circular polarizer includes a circular polarizer output section, a polarization conversion section, and a waveguide conversion section. The circular polarizer output section is an internal cavity structure located at the first flange end of the circular polarizer, used for mounting and fixing with the waveguide conversion section. The circular polarizer output section has a hollow, symmetrical, octagonal cross-section. The faces containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output section are parallel to the faces containing the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide section. The faces containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section are parallel to the faces containing the 2nd, 4th, 6th, and 8th sides of the first octagonal waveguide section. The outer wall of the polarization conversion section has a quadrilateral cross-section, and the polarization conversion section has a hollow cavity. The polarization conversion section connects the circular polarizer output section and the waveguide conversion section, and includes polarization corrugated teeth, polarization corrugated grooves, and a waveguide output end. The waveguide output end is hollow. The waveguide transformation section is a quadrilateral structure located on the side of the polarization transformation section closest to the output section of the circular polarizer. The faces containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section are coplanar with the faces containing the four sides of the waveguide output end. Polarization corrugated teeth and polarization corrugated grooves are alternately arranged in the cavity inside the polarization transformation section. The inner wall of the polarization transformation section with polarization corrugated teeth and polarization corrugated grooves is parallel to the face containing the 2nd or 6th side of the circular polarizer output section. The waveguide transformation section is an inner cavity structure located at the second flange end of the circular polarizer, which is connected to the broadband 45° polarization rotator. The waveguide transformation section is a hollow, symmetrical, quadrilateral structure. The waveguide transformation section is used for mounting and fixing non-equivalent octagonal waveguides. The faces containing the four sides of the waveguide transformation section are parallel to the faces containing the four sides of the waveguide output end.

[0015] A non-uniform octagonal waveguide is installed in the waveguide transformation section; the external dimensions of the non-uniform octagonal waveguide are matched with the internal cavity dimensions of the waveguide transformation section; the outer wall section of the non-uniform octagonal waveguide is quadrilateral; the inner wall section of the non-uniform octagonal waveguide is non-uniform octagonal; the plane containing the 2nd, 4th, 6th, and 8th sides of the inner wall of the uniform octagonal waveguide is coplanar with the plane containing the four sides of the waveguide transformation section;

[0016] The broadband 45° polarization rotator is used to rotate the TE10 and TE01 modes of the square waveguide by 45°, thereby illuminating the circular polarizer at 45° and achieving circular polarization. Along the direction from the circular polarizer to the broadband 45° polarization rotator, a non-equilateral octagonal waveguide, an equilateral octagonal waveguide, and a circular waveguide are sequentially arranged at the center of the broadband 45° polarization rotator. The non-equilateral octagonal waveguide has a hollow symmetry structure with an octagonal cross-section; the equilateral octagonal waveguide has a hollow symmetry structure with an octagonal cross-section; and the circular waveguide has a cylindrical cavity structure.

[0017] An orthogonal mode coupler is assembled from multiple solid components to form a cavity structure. This cavity structure includes a first square waveguide segment, a second square waveguide segment, a first coupling arm, a second coupling arm, a third coupling arm, a fourth coupling arm, a left-handed spiral waveguide, and a right-handed spiral waveguide. The first square waveguide segment is used to achieve impedance transition between the second square waveguide segment and the circular waveguide. The first square waveguide segment is a cuboid cavity structure. The second square waveguide segment is a cuboid cavity structure. The first and second square waveguide segments have different structural dimensions. The first, second, third, and fourth coupling arms are respectively formed by the front, rear, and... of the second square waveguide segment. Starting from the left and right, the solid structure surrounding the center of the orthogonal mode coupler extends in a direction away from the first square waveguide segment; each of the first, second, third, and fourth coupling arms directly couples to the electromagnetic waves of the square waveguide cavity; the first and second coupling arms are symmetrically arranged, as are the third and fourth coupling arms; each of the first, second, third, and fourth coupling arms includes both inclined and vertical portions; the connection points between the inclined portions of the first, second, third, and fourth coupling arms and the second square waveguide segment are... A chamfered waveguide; a left-handed synthesizing waveguide includes a first connecting waveguide segment, a second connecting waveguide segment, a first synthesizing segment, and a left-handed output waveguide port; a first coupling arm is connected to the first connecting waveguide segment, and a second coupling arm is connected to the second connecting waveguide segment; the first and second connecting waveguide segments are solid structures arranged around the center of an orthogonal mode coupler, extending axially in a direction away from the first waveguide segment, and converging at the first synthesizing segment; the first synthesizing segment continues to extend axially in a direction away from the first waveguide segment to form a left-handed output waveguide port; the left-handed synthesizing waveguide connects to the left-handed output port via the left-handed output waveguide port. The right-hand synthesizing waveguide includes a third connecting waveguide segment, a fourth connecting waveguide segment, a second synthesizing segment, and a right-hand output waveguide port. The third coupling arm is connected to the third connecting waveguide segment, and the fourth coupling arm is connected to the fourth connecting waveguide segment. The third and fourth connecting waveguide segments are solid structures arranged around the center of the orthogonal mode coupler. They first extend axially in a direction away from the first waveguide segment, and then turn 90° before converging at the second synthesizing segment. The second synthesizing segment continues to extend in a direction perpendicular to the axial direction to form the right-hand output waveguide port. The right-hand synthesizing waveguide is connected to the right-hand output port through the right-hand output waveguide port.

[0018] In conjunction with the first aspect, in certain implementations of the first aspect, the radiating horn satisfies at least one of the following:

[0019] The depth dimension of the annular groove formed by the choke corrugated horn is 1 / 4λ to 1 / 2λ, where λ is the wavelength of the center frequency;

[0020] The width of the annular groove formed by the choke corrugated horn is 1 / 3λ to λ;

[0021] The inner diameter of the second end of the output tapered section is 5% to 20% larger than the inner diameter of the transmission circular waveguide;

[0022] The inner diameter of the transmission circular waveguide is controlled within the TE11 working transmission region of the circular waveguide master mode.

[0023] In conjunction with the first aspect, in certain implementations of the first aspect, the radiating horn satisfies at least one of the following:

[0024] The inner diameter of the circular waveguide section should be controlled within the TE11 operating transmission range of the circular waveguide master mode;

[0025] The side lengths of the first octagonal waveguide segment are equal;

[0026] The length of the first octagonal waveguide segment in the axial direction ranges from 1 / 20λ to 1 / 10λ, where λ is the wavelength of the center frequency.

[0027] The lengths of the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment are greater than the lengths of the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment.

[0028] The first, third, fifth, and seventh sides of the second octagonal waveguide segment are of equal length, and the second, fourth, sixth, and eighth sides are of equal length. The second, fourth, sixth, and eighth sides of the second octagonal waveguide segment are shorter than the first, third, fifth, and seventh sides of the second octagonal waveguide segment.

[0029] The length of the second octagonal waveguide segment in the axial direction ranges from 1 / 10λ to 1 / 4λ.

[0030] In conjunction with the first aspect, in certain implementations of the first aspect, the circular polarizer satisfies at least one of the following:

[0031] The length of each polarization corrugated tooth is different. Along the axis of the circular polarizer, the length of the polarization corrugated teeth first decreases and then increases.

[0032] The length of the polarized corrugated teeth ranges from 1 / 30λ to 1 / 10λ, where λ is the wavelength of the center frequency.

[0033] The depth of each polarization corrugated tooth is different. Along the axis of the circular polarizer, the depth of the polarization corrugated teeth first increases and then decreases.

[0034] The depth dimension of the polarized corrugated teeth ranges from 1 / 10λ to 1 / 5λ.

[0035] The spacing between two adjacent polarized corrugated teeth is the same;

[0036] The number of polarized corrugated teeth shall not be less than 10 pairs;

[0037] The output section of the circular polarizer is a non-equilateral octagonal waveguide; the 1st, 3rd, 5th, and 7th sides of the output section of the circular polarizer are equilateral, the 2nd, 4th, 6th, and 8th sides are equilateral, and adjacent sides are unequal.

[0038] The plane containing the 1st, 3rd, 5th, and 7th sides of the output segment of the circular polarizer is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment;

[0039] The waveguide output is an equilateral quadrilateral waveguide;

[0040] The waveguide transformation section is a quadrilateral cavity structure with rounded corners.

[0041] In conjunction with the first aspect, in some implementations of the first aspect, the side length of the octagonal cavity of the non-uniform octagonal waveguide is set to be the same as the size of the output segment of the circular polarizer; the planes containing the 1st, 3rd, 5th, and 7th sides of the non-uniform octagonal waveguide are coplanar with the planes containing the 1st, 3rd, 5th, and 7th sides of the output segment of the circular polarizer, and the planes containing the 2nd, 4th, 6th, and 8th sides of the non-uniform octagonal waveguide are coplanar with the planes containing the 2nd, 4th, 6th, and 8th sides of the output segment of the circular polarizer.

[0042] In conjunction with the first aspect, in certain implementations of the first aspect, the broadband 45° polarization rotator satisfies at least one of the following:

[0043] The side lengths of the non-equilateral octagonal waveguide are equal for the 1st, 3rd, 5th, and 7th sides, equal for the 2nd, 4th, 6th, and 8th sides, and unequal for adjacent sides;

[0044] The plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide.

[0045] The plane containing the 1st, 3rd, 5th, and 7th sides of the equilateral octagonal waveguide is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide.

[0046] The diameter of the circumcircle of an equilateral octagonal waveguide is larger than the diameter of a circular waveguide.

[0047] The radius of the inscribed circle of a non-equilateral octagonal waveguide is the same as that of an equilateral octagonal waveguide.

[0048] In conjunction with the first aspect, in some implementations of the first aspect, the tilt angles of the tilted portions of the first coupling arm, the second coupling arm, the third coupling arm, and the fourth coupling arm are the same, and the tilt lengths are the same; the tilted portions of the first coupling arm, the second coupling arm, the third coupling arm, and the fourth coupling arm are evenly distributed around the central axis at 90°.

[0049] In conjunction with the first aspect, in certain implementations of the first aspect, the orthogonal mode coupler satisfies at least one of the following:

[0050] The inner sides of the first connecting waveguide section and the inner sides of the second connecting waveguide section each have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is not less than 3.

[0051] Both the outer side of the first connecting waveguide segment and the outer side of the second connecting waveguide segment have several impedance steps; the specific size of the impedance steps is determined by optimization, and the number of impedance steps is not less than 3.

[0052] In conjunction with the first aspect, in certain implementations of the first aspect, the orthogonal mode coupler satisfies at least one of the following:

[0053] The 90° turning points of the third and fourth connecting waveguide sections each have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is no less than 3.

[0054] The outer side of the third connecting waveguide segment extending in a direction perpendicular to the axial direction, and the outer side of the fourth connecting waveguide segment extending in a direction perpendicular to the axial direction, both have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is not less than 3.

[0055] The inner side of the third connecting waveguide segment extending in a direction perpendicular to the axial direction, and the inner side of the fourth connecting waveguide segment extending in a direction perpendicular to the axial direction, both have several impedance steps; the specific impedance step size is determined by optimization, and the number of impedance steps is not less than 2.

[0056] In conjunction with the first aspect, in some implementations of the first aspect, the left-hand and right-hand output ports are two standard waveguide-to-2.92-K coaxial conversion ports, realizing the conversion of electromagnetic waves from waveguide transmission to coaxial transmission.

[0057] Compared with the prior art, the solution provided by the present invention has at least the following beneficial technical effects:

[0058] It achieves high-performance broadband coverage within 55% of the operating bandwidth. The feed assembly utilizes compact, small, and broadband components, including a compact square-to-circular converter, a high-performance multi-degree-of-freedom broadband circular polarizer, a compact 45° polarization rotator, and a compact broadband high-efficiency orthogonal mode coupler, making the entire feed more compact and easy to integrate with the reflector antenna. The key components inside the feed assembly are easy to manufacture, have controllable precision, and can operate in the Ka band without debugging or tuning pins.

[0059] This feed achieves performance in terms of wide bandwidth, miniaturization, compactness, and dual polarization, while also possessing advantages such as simple structure, high rigidity, and high reliability, making it suitable for tasks such as inter-satellite communication and broadband signal reception. Attached Figure Description

[0060] Figure 1This is a schematic diagram of a small, compact, wideband Ka-band satellite feed mounted on an upper reflector system.

[0061] Figure 2 This is a schematic diagram of a small, compact, wideband feed for a spaceborne Ka-band frequency.

[0062] Figure 3 This is a cross-sectional view of a radiating horn.

[0063] Figure 4 This is a three-dimensional diagram of a radiating loudspeaker.

[0064] Figure 5 This is a top view of a radiating speaker.

[0065] Figure 6 This is a cross-sectional view of a circular polarizer.

[0066] Figure 7 This is a three-dimensional diagram of a circular polarizer.

[0067] Figure 8 This is a schematic diagram of an octagonal waveguide.

[0068] Figure 9 This is a cross-sectional view of a small, compact, wideband Ka-band satellite feed in the first section.

[0069] Figure 10 This is a cross-sectional view of a small, compact, wideband Ka-band satellite feed in the second section.

[0070] Figure 11 This is a schematic diagram of a broadband 45° polarization rotator.

[0071] Figure 12 This is a schematic diagram of the internal cavity of the square waveguide section, which includes the polarization transformation section, the non-uniform octagonal waveguide, the broadband 45° polarization rotator, and the orthogonal mode coupler.

[0072] Figure 13 This is a schematic diagram of an orthogonal mode coupler.

[0073] Figure 14 This is a schematic diagram of the internal cavity of an orthogonal mode coupler.

[0074] Figure 15 This is a schematic diagram of the central cross-section of the inner cavity of an orthogonal mode coupler. Detailed Implementation

[0075] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0076] The present invention provides a small, compact, wideband, dual-polarized, high-performance Ka-band feed that operates in the 17GHz to 28GHz frequency band.

[0077] Figure 1 A schematic diagram is shown of a small, compact, wideband satellite-borne Ka-band feed mounted on an upper reflector system. The main reflector dimension of this system is, for example, 300 mm in diameter.

[0078] Figure 2 A schematic diagram of a small, compact, wideband Ka-band satellite feed is shown. The feed includes a radiating horn 1, a wideband circular polarizer 2, an asymmetrical octagonal waveguide 3, a wideband 45° polarization rotator 4, an orthogonal mode coupler 5, a left-handed output port 6, and a right-handed output port 7.

[0079] Figure 3 , Figure 4 A schematic diagram of a radiating horn 1 is shown. The radiating horn 1 includes a choke corrugated horn 11, a transmission circular waveguide 12, a waveguide transformer 13, and an output tapered section 14. The radiating horn is used to achieve electromagnetic wave radiation and to uniformly illuminate the reflecting surface.

[0080] The choke bellows 11 and the output tapered section 14 are located on one side of the transmission circular waveguide 12, while the waveguide transformer 13 is located on the other side. The transmission circular waveguide 12 is a hollow cylinder. The inner wall of the output tapered section 14 is a conical surface, and the outer wall is a cylindrical surface. The first end of the output tapered section 14 is directly connected to the transmission circular waveguide 12, and the inner diameter of the first end of the output tapered section 14 is the same as that of the transmission circular waveguide 12. The inner diameter of the second end of the output tapered section 14 is larger than that of the transmission circular waveguide 12. The choke bellows 11 is located on the periphery of the output tapered section 14 to form an annular groove on the outer side of the output tapered section 14. The waveguide transformer 13 is an internal cavity structure located at the flange end of the radiating bell 1, used to connect the broadband circular polarizer 2 and achieve a good impedance matching transition between the radiating bell 1 and the broadband circular polarizer 2.

[0081] Furthermore, the depth of the annular groove formed by the choke bellows 11 ranges from 1 / 4λ to 1 / 2λ (the depth direction is parallel to the axial direction of the choke bellows 11), and the width of the annular groove formed by the choke bellows 11 ranges from 1 / 3λ to λ (the width direction is perpendicular to the axial direction of the choke bellows 11), where λ is the wavelength of the center frequency. The specific dimensions can be determined through optimization.

[0082] Furthermore, the inner diameter of the second end of the output tapered section 14 is 5% to 20% larger than the inner diameter of the transmission circular waveguide 12. The specific dimensions can be determined based on optimization.

[0083] Furthermore, the inner diameter of the transmission circular waveguide 12 should be controlled within the operating transmission range of the main mode TE11 of the circular waveguide.

[0084] Furthermore, Figure 4 , Figure 5A schematic diagram of waveguide transformation 13 is shown. Along the direction from the radiating horn 1 to the broadband circular polarizer 2, waveguide transformation 13 sequentially includes a circular waveguide segment 131, a first octagonal waveguide segment 132, and a second octagonal waveguide segment 133. The circular waveguide segment 131 is connected to the transmission circular waveguide 12 and is in the shape of a hollow cylinder. The first octagonal waveguide segment 132 is connected between the circular waveguide segment 131 and the second octagonal waveguide segment 133, and has a hollow, symmetrical structure with an octagonal cross-section. The second octagonal waveguide segment 133 also has a hollow, symmetrical structure with an octagonal cross-section. The structural dimensions of the first octagonal waveguide segment 132 and the second octagonal waveguide segment 133 are different. The faces containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment 133 are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment 132. The faces containing the 2nd, 4th, 6th, and 8th sides of the second octagonal waveguide segment 133 are parallel to the faces containing the 2nd, 4th, 6th, and 8th sides of the first octagonal waveguide segment 132. The specific dimensions of the waveguide transformation 13 can be determined based on the final optimization.

[0085] Furthermore, the lengths of the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment 133 are greater than the lengths of the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment 132. Adjacent sides of the second octagonal waveguide segment 133 are of unequal length; that is, the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment 133 are of equal length, and the 2nd, 4th, 6th, and 8th sides are of equal length. The lengths of the 2nd, 4th, 6th, and 8th sides of the second octagonal waveguide segment 133 are less than the lengths of the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment 133.

[0086] Furthermore, the side lengths of the first octagonal waveguide segment 132 are equal.

[0087] Furthermore, the axial length of the first octagonal waveguide segment 132 ranges from 1 / 20λ to 1 / 10λ. Specific detailed dimensions can be determined based on the final optimization.

[0088] Furthermore, the axial length of the second octagonal waveguide segment 133 ranges from 1 / 10λ to 1 / 4λ. Specific detailed dimensions can be determined based on the final optimization.

[0089] Furthermore, the inner diameter of the circular waveguide section 131 should be controlled within the operating transmission range of the circular waveguide master mode TE11.

[0090] Figure 6 , Figure 7 A schematic diagram of circular polarizer 2 is shown. Circular polarizer 2 includes a circular polarizer output section 21, a polarization conversion section 22, and a waveguide conversion section 23.

[0091] The circular polarizer output section 21 is an internal cavity structure located at the first flange end of the circular polarizer 2, used to connect the radiating horn 1 and achieve good impedance matching transition. The circular polarizer output section 21 is used for mounting and fixing with the waveguide transformer 13. The circular polarizer output section 21 has a hollow, symmetrical, octagonal cross-section. The faces containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output section 21 are parallel to the faces containing the 1st, 3rd, 5th, and 7th sides of the aforementioned first octagonal waveguide section 132. The faces containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section 21 are parallel to the faces containing the 2nd, 4th, 6th, and 8th sides of the aforementioned first octagonal waveguide section 132.

[0092] The outer wall of the polarization conversion section 22 has a quadrilateral cross-section, and the interior of the polarization conversion section 22 has a cavity. The polarization conversion section 22 connects the circular polarizer output section 21 and the waveguide conversion section 23, and includes polarization corrugated teeth 221, polarization corrugated grooves 222, and a waveguide output end 223. The waveguide output end 223 has a hollow, symmetrical, quadrilateral cross-section and is located on the side of the polarization conversion section 22 closest to the circular polarizer output section 21. The planes containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section 21 are coplanar with the planes containing the four sides of the waveguide output end 223. The polarization corrugated teeth 221 and polarization corrugated grooves 222 are alternately arranged inside the cavity of the polarization conversion section 22. The inner wall of the polarization conversion section 22, where the polarization corrugated teeth 221 and polarization corrugated grooves 222 are located, is parallel to the plane containing the 2nd or 6th side of the circular polarizer output section 21.

[0093] The waveguide transformation section 23 is an internal cavity structure located at the second flange end of the circular polarizer 2. The second flange end of the circular polarizer 2 is connected to the broadband 45° polarization rotator 4. The waveguide transformation section 23 is used to set the non-uniform octagonal waveguide 3 and achieve good impedance matching transition. The waveguide transformation section 23 has a hollow, symmetrical, quadrilateral cross-section. The waveguide transformation section 23 is used for mounting and fixing with the non-uniform octagonal waveguide 3, realizing the conversion from a square waveguide to an octagonal waveguide. The four sides of the waveguide transformation section 23 are parallel to the four sides of the waveguide output end 223.

[0094] Furthermore, the length of each tooth of the polarization corrugated tooth 221 (the length direction is parallel to the axial direction of the circular polarizer 2) is different. In one embodiment, the length of the polarization corrugated tooth 221 first decreases and then increases along the axial direction of the circular polarizer 2.

[0095] Furthermore, the length of the polarized corrugated tooth 221 ranges from 1 / 30λ to 1 / 10λ.

[0096] Furthermore, the depth of each tooth of the polarization corrugated tooth 221 (the depth direction is perpendicular to the axial direction of the circular polarizer 2) can be different or the same. In one embodiment, the depth of the polarization corrugated tooth 221 first increases and then decreases along the axial direction of the circular polarizer 2.

[0097] Furthermore, the depth dimension of the polarized corrugated tooth 221 ranges from 1 / 10λ to 1 / 5λ.

[0098] Furthermore, the spacing between two adjacent polarized corrugated teeth 221 is the same. The specific number of polarized corrugated teeth 221 depends on the optimization, but is generally no less than 10 pairs.

[0099] Furthermore, the output section 21 of the circular polarizer is a non-equilateral octagonal waveguide. The 1st, 3rd, 5th, and 7th sides of the output section 21 of the circular polarizer are equilateral, the 2nd, 4th, 6th, and 8th sides are equilateral, and adjacent sides are unequal.

[0100] Furthermore, the plane containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output segment 21 is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment 133.

[0101] Furthermore, the waveguide output terminal 223 is an equilateral quadrilateral waveguide.

[0102] Furthermore, waveguide transformation segment 23 is a quadrilateral cavity structure with rounded corners.

[0103] Figure 8 A schematic diagram of the non-uniform octagonal waveguide 3 is shown. Figure 9 As shown, a non-uniform octagonal waveguide 3 is disposed within the waveguide transformation section 23. The external dimensions of the non-uniform octagonal waveguide 3 are matched with the internal dimensions of the waveguide transformation section 23. The outer wall cross-section of the non-uniform octagonal waveguide 3 is quadrilateral, and the four corners of the quadrilateral can be rounded. The inner wall cross-section of the non-uniform octagonal waveguide 3 is a non-uniform octagon. The plane containing the 2nd, 4th, 6th, and 8th sides of the inner wall of the uniform octagonal waveguide 3 is coplanar with the plane containing the four sides of the waveguide transformation section 23.

[0104] Furthermore, the side length of the octagonal cavity of the non-uniform octagonal waveguide 3 is the same as the size of the output section 21 of the circular polarizer. The faces containing the 1st, 3rd, 5th, and 7th sides of the non-uniform octagonal waveguide 3 are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output section 21, and the faces containing the 2nd, 4th, 6th, and 8th sides of the non-uniform octagonal waveguide 3 are coplanar with the faces containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section 21.

[0105] Figure 9 , Figure 10 Cross-sectional views of the feed assembly in two vertical directions are given.

[0106] Figure 11A schematic diagram of a broadband 45° polarization rotator 4 is shown. The broadband 45° polarization rotator 4 is used to rotate the square waveguide TE10 and TE01 modes by 45°, thereby illuminating the circular polarizer 2 at a 45° angle and achieving circular polarization. Along the direction from the circular polarizer 2 to the broadband 45° polarization rotator 4, a non-equilateral octagonal waveguide 41, an equilateral octagonal waveguide 42, and a circular waveguide 43 are sequentially arranged at the center of the broadband 45° polarization rotator 4. The non-equilateral octagonal waveguide 41 has a hollow, symmetrical structure with an octagonal cross-section. The equilateral octagonal waveguide 42 has a hollow, symmetrical structure with an octagonal cross-section. The circular waveguide 43 has a cylindrical cavity structure.

[0107] Furthermore, the side lengths of the non-equilateral octagonal waveguide 41 are equal for the 1st, 3rd, 5th, and 7th sides, and equal for the 2nd, 4th, 6th, and 8th sides, with adjacent unequal sides.

[0108] Furthermore, the plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide 41 is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide 3.

[0109] Furthermore, the faces containing the 1st, 3rd, 5th, and 7th sides of the equilateral octagonal waveguide 42 are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide 41.

[0110] Furthermore, the circumscribed circle diameter of the equilateral octagonal waveguide 42 is larger than the diameter of the circular waveguide 43.

[0111] Furthermore, the radius of the inscribed circle of the non-equilateral octagonal waveguide 41 is equal to the radius of the inscribed circle of the equilateral octagonal waveguide 42.

[0112] For ease of explanation, Figure 12 A schematic diagram of the cavity of the square waveguide segment 51, which involves polarization transformation segment 22, non-equiangular octagonal waveguide 3, broadband 45° polarization rotator 4, and orthogonal mode coupler 5, is given.

[0113] Figures 13 to 15 A schematic diagram of orthogonal mode coupler 5 is shown. (See diagram below.) Figure 13 As shown, the orthogonal mode coupler 5 is assembled from multiple solid components to form a special cavity structure. This cavity structure includes a first square waveguide segment 51, a second square waveguide segment 52, a first coupling arm 53, a second coupling arm 54, a third coupling arm 55, a fourth coupling arm 56, a left-handed spiral combining waveguide 57, and a right-handed spiral combining waveguide 58. For ease of explanation, Figure 14 A schematic diagram of the internal cavity of the orthogonal mode coupler 5 is shown. Figure 15 A schematic diagram of the central cross-section of the inner cavity of the orthogonal mode coupler 5 is shown.

[0114] like Figure 13 and 14As shown, the first square waveguide segment 51 is used to achieve the impedance transition between the second square waveguide segment 52 and the circular waveguide 43. The first square waveguide segment 51 is a cuboid cavity structure. The second waveguide segment 52 is a cuboid cavity structure. The structural dimensions of the first square waveguide segment 51 and the second waveguide segment 52 are different.

[0115] like Figure 13 and 14 As shown, the first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 originate from the front, back, left, and right directions of the second square waveguide segment 52, respectively, and extend around the solid structure set at the center of the orthogonal mode coupler 5, in a direction away from the first square waveguide segment 51. Each coupling arm channel of the first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 directly couples to the electromagnetic waves of the square waveguide cavity 52. ​​The first coupling arm 53 and the second coupling arm 54 are symmetrically arranged, as are the third coupling arm 55 and the fourth coupling arm 56. The first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 all include inclined and vertical portions. A characteristic of the first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 is that the connection part with the second square waveguide segment 52 is a chamfered waveguide.

[0116] like Figure 13 and 15 As shown, the left-handed synthesizing waveguide 57 includes a first connecting waveguide segment 571, a second connecting waveguide segment 572, a first synthesizing segment 573, and a left-handed output waveguide port 574. A first coupling arm 53 is connected to the first connecting waveguide segment 571, and a second coupling arm 54 is connected to the second connecting waveguide segment 572. The first connecting waveguide segment 571 and the second connecting waveguide segment 572 are solid structures arranged around the center of the orthogonal mode coupler 5, extending axially in a direction away from the first square waveguide segment 51, and converging at the first synthesizing segment 573. The first synthesizing segment 573 continues to extend axially in a direction away from the first square waveguide segment 51 to form the left-handed output waveguide port 574, thereby connecting the left-handed synthesizing waveguide 57 to the left-handed output port 6 through the left-handed output waveguide port 574.

[0117] like Figure 14As shown, the right-handed synthesizing waveguide 58 includes a third connecting waveguide segment 581, a fourth connecting waveguide segment 582, a second synthesizing segment 583, and a right-handed output waveguide port 584. A third coupling arm 55 is connected to the third connecting waveguide segment 581, and a fourth coupling arm 56 is connected to the fourth connecting waveguide segment 582. The third connecting waveguide segment 581 and the fourth connecting waveguide segment 582 are solid structures arranged around the center of the orthogonal mode coupler 5. They first extend axially in a direction away from the first waveguide segment 51, then turn 90° and converge at the second synthesizing segment 583. The second synthesizing segment 583 continues to extend in a direction perpendicular to the axial direction to form the right-handed output waveguide port 584. Thus, the right-handed synthesizing waveguide 58 is connected to the right-handed output port 7 through the right-handed output waveguide port 584.

[0118] Furthermore, the inclined portions of the first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 have the same inclination angle and the same inclination length. The inclined portions of the first coupling arm 53, the second coupling arm 54, the third coupling arm 55, and the fourth coupling arm 56 are evenly distributed around the central axis at 90°.

[0119] Furthermore, the specific dimensions of the left-handed output waveguide port 574 can be either a standard waveguide for the corresponding operating frequency or a non-standard waveguide port.

[0120] Furthermore, the specific dimensions of the right-hand output waveguide port 584 can be either a standard waveguide for the corresponding operating frequency or a non-standard waveguide port.

[0121] Furthermore, both the inner sides of the first connecting waveguide segment 571 and the inner sides of the second connecting waveguide segment 572 have several chamfered surfaces. The specific dimensions of the chamfered surfaces are determined by optimization, and the number of chamfered surfaces is no less than three.

[0122] Furthermore, both the outer sides of the first connecting waveguide segment 571 and the outer sides of the second connecting waveguide segment 572 have several impedance steps. The specific size of the impedance steps is determined by optimization, and the number of impedance steps is no less than three.

[0123] Furthermore, the 90° turning portions of the third connecting waveguide segment 581 and the fourth connecting waveguide segment 582 both have several chamfered surfaces. The specific dimensions of the chamfered surfaces are determined by optimization, and the number of chamfered surfaces is no less than three.

[0124] Furthermore, both the outer side of the portion of the third connecting waveguide segment 581 extending in a direction perpendicular to the axial direction and the outer side of the portion of the fourth connecting waveguide segment 582 extending in a direction perpendicular to the axial direction have several chamfered surfaces. The specific dimensions of the chamfered surfaces are determined by optimization, and the number of chamfered surfaces is not less than three.

[0125] Furthermore, both the inner side of the portion of the third connecting waveguide segment 581 extending in a direction perpendicular to the axial direction and the inner side of the portion of the fourth connecting waveguide segment 582 extending in a direction perpendicular to the axial direction have several impedance steps. The specific size of the impedance steps is determined by optimization, and the number of impedance steps is not less than two.

[0126] The orthogonal mode coupler 5 provided by this invention does not require tuning pillars, isolation pillars and other tuning and debugging measures, and solves the problems of impedance characteristic singularity and jumping point that may be caused by small tuning pillars, as well as the problems of micro-discharge and passive intermodulation.

[0127] Furthermore, the left-hand output port 6 and the right-hand output port 7 are two standard waveguide-to-2.92-K coaxial conversion ports. One end is used to connect the cable assembly, and the other end is connected to the left-hand output waveguide port 574 and the right-hand output waveguide port 584 respectively, realizing the conversion of electromagnetic waves from waveguide transmission to coaxial transmission.

[0128] This embodiment ensures that the feed antenna operates within the 17GHz to 28GHz frequency band. When illuminating a 300mm primary reflector assembly, it maintains an aperture efficiency of no less than 68% across the entire frequency range, with cross-polarization better than -25dB and a reflection coefficient better than -25dB. It achieves broadband, small size, compact design, and dual circular (linear) polarization while also possessing advantages such as simple structure, high rigidity, and high reliability.

[0129] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A spaceborne Ka-band small, compact, wideband feed, characterized in that, It includes a radiating horn (1), a broadband circular polarizer (2), an octagonal waveguide (3), a broadband 45° polarization rotator (4), an orthogonal mode coupler (5), a left-handed output port (6), and a right-handed output port (7); The radiating horn (1) includes a choked corrugated horn (11), a transmission circular waveguide (12), a waveguide transformer (13), and an output tapered section (14); the choked corrugated horn (11) and the output tapered section (14) are located on one side of the transmission circular waveguide (12), and the waveguide transformer (13) is located on the other side of the transmission circular waveguide (12); the transmission circular waveguide (12) is a hollow cylinder; the inner wall of the output tapered section (14) is a conical surface, and the outer wall is a cylindrical surface; the first end of the output tapered section (14) is connected to the transmission circular waveguide. (12) Direct connection, the first end of the output tapered section (14) has the same inner diameter as the transmission circular waveguide (12), and the second end of the output tapered section (14) has a larger inner diameter than the transmission circular waveguide (12); the choke corrugated horn (11) is located on the periphery of the output tapered section (14) to form an annular groove on the outside of the output tapered section (14); the waveguide converter (13) is an internal cavity structure set at the flange end of the radiating horn (1) to connect the broadband circular polarizer (2); along the radiating horn (1) In the direction of the broadband circular polarizer (2), the waveguide transform (13) is provided with a circular waveguide segment (131), a first octagonal waveguide segment (132), and a second octagonal waveguide segment (133) in sequence; the circular waveguide segment (131) is connected to the transmission circular waveguide (12) and is in the shape of a hollow cylinder; the first octagonal waveguide segment (132) is connected between the circular waveguide segment (131) and the second octagonal waveguide segment (133) and is in the shape of a hollow symmetrical structure with an octagonal cross section; the second octagonal waveguide segment (133) The structure is hollow and symmetrical with an octagonal cross-section; the structural dimensions of the first octagonal waveguide segment (132) and the second octagonal waveguide segment (133) are different; the faces containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment (133) are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment (132); the faces containing the 2nd, 4th, 6th, and 8th sides of the second octagonal waveguide segment (133) are parallel to the faces containing the 2nd, 4th, 6th, and 8th sides of the first octagonal waveguide segment (132). The circular polarizer (2) includes a circular polarizer output section (21), a polarization conversion section (22), and a waveguide conversion section (23). The circular polarizer output section (21) is an internal cavity structure located at the first flange end of the circular polarizer (2), used for installation and fixation with the waveguide conversion section (13). The circular polarizer output section (21) has a hollow symmetrical structure with an octagonal cross-section. The plane containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output section (21) is parallel to the plane containing the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide section (132). The plane containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section (21) is parallel to the plane containing the 2nd, 4th, 6th, and 8th sides of the first octagonal waveguide section (132); the outer wall cross-section of the polarization conversion section (22) is quadrilateral, and the polarization conversion section (22) has a cavity inside; the polarization conversion section (22) is connected between the circular polarizer output section (21) and the waveguide conversion section (23), and includes polarization corrugated teeth (221), polarization corrugated grooves (222), and waveguide output end (223); the waveguide output end (223) is shaped as follows: A hollow, symmetrical, quadrilateral structure is located on the side of the polarization conversion section (22) near the circular polarizer output section (21); the surfaces containing the 2nd, 4th, 6th, and 8th sides of the circular polarizer output section (21) are coplanar with the surfaces containing the four sides of the waveguide output end (223); polarization corrugated teeth (221) and polarization corrugated grooves (222) are alternately arranged in the cavity inside the polarization conversion section (22); the inner walls of the polarization conversion section (22) with polarization corrugated teeth (221) and polarization corrugated grooves (222) are arranged on the circular polarizer. The second or sixth side of the output section (21) is parallel to the plane; the waveguide transformation section (23) is an inner cavity structure set in the second flange end of the circular polarizer (2), the second flange end of the circular polarizer (2) is connected to the broadband 45° polarization rotator (4), the waveguide transformation section (23) has a hollow symmetrical structure with a quadrilateral cross section; the waveguide transformation section (23) is used to install and fix the non-equivalent octagonal waveguide (3); the planes on which the four sides of the waveguide transformation section (23) are located are parallel to the planes on which the four sides of the waveguide output end (223) are located; An unequal octagonal waveguide (3) is installed in the waveguide transformation section (23); the external dimensions of the unequal octagonal waveguide (3) are matched with the internal cavity dimensions of the waveguide transformation section (23); the outer wall profile of the unequal octagonal waveguide (3) is quadrilateral; the inner wall profile of the unequal octagonal waveguide (3) is an unequal octagonal; the planes containing the 2nd, 4th, 6th, and 8th sides of the inner wall of the equal octagonal waveguide (3) are coplanar with the planes containing the four sides of the waveguide transformation section (23); The broadband 45° polarization rotator (4) is used to rotate the square waveguide TE10 and TE01 modes by 45°, and to illuminate the circular polarizer (2) at 45°, thereby realizing the circular polarization function. Along the direction from the circular polarizer (2) to the broadband 45° polarization rotator (4), the center of the broadband 45° polarization rotator (4) is provided with a non-equilateral octagonal waveguide (41), an equilateral octagonal waveguide (42), and a circular waveguide (43) in sequence. The non-equilateral octagonal waveguide (41) has a hollow symmetrical structure with an octagonal cross section. The equilateral octagonal waveguide (42) has a hollow symmetrical structure with an octagonal cross section. The circular waveguide (43) has a cylindrical cavity structure. The orthogonal mode coupler (5) is assembled into a cavity structure by multiple solid components. The cavity structure includes a first square waveguide segment (51), a second square waveguide segment (52), a first coupling arm (53), a second coupling arm (54), a third coupling arm (55), a fourth coupling arm (56), a left-handed composite waveguide (57), and a right-handed composite waveguide (58). The first square waveguide segment (51) is used to realize the impedance transition between the second square waveguide segment (52) and the circular waveguide (43). The first square waveguide segment (51) is a cuboid cavity structure. The second square waveguide segment (52) is a cuboid cavity structure. The structural dimensions of the first square waveguide segment (51) and the second square waveguide segment (52) are different. The first coupling arm (53), the second coupling arm (54), the second coupling arm (55), the third coupling arm (56), the fourth coupling arm (57), the fifth coupling arm (58), the sixth coupling arm (59), the seventh coupling arm (50), the eighth coupling arm (51), the ninth coupling arm (51), the eleventh coupling arm (52), the eleventh coupling arm (53), the eleventh coupling arm (54), the eleventh coupling arm (55), the eleventh coupling arm (56), the eleventh coupling arm (57), and the eleventh coupling arm (58) are all located in the cavity structure. 54), the third coupling arm (55), and the fourth coupling arm (56) originate from the front, back, left, and right directions of the second square waveguide segment (52), respectively, and extend around the solid structure set at the center of the orthogonal mode coupler (5), in a direction away from the first square waveguide segment (51); each coupling arm channel of the first coupling arm (53), the second coupling arm (54), the third coupling arm (55), and the fourth coupling arm (56) directly couples the electromagnetic waves of the square waveguide cavity (52); the first coupling arm (53) and the second coupling arm (54) are symmetrically arranged, and the third coupling arm (55) and the fourth coupling arm (56) are symmetrically arranged; the first coupling arm (53), the second coupling arm (54), the third coupling arm (55), and the fourth coupling arm (56) are symmetrically arranged. 56) All include inclined and vertical parts; the inclined parts of the first coupling arm (53), the second coupling arm (54), the third coupling arm (55), and the fourth coupling arm (56) are connected to the second square waveguide section (52) in a chamfered waveguide; the left-handed synthesizing waveguide (57) includes the first connecting waveguide section (571), the second connecting waveguide section (572), the first synthesizing section (573), and the left-handed output waveguide port (574); the first coupling arm (53) is connected to the first connecting waveguide section (571), and the second coupling arm (54) is connected to the second connecting waveguide section (572); the first connecting waveguide section (571) and the second connecting waveguide section (572) are solid structures arranged around the center of the orthogonal mode coupler (5). The first composite waveguide (57) extends axially in a direction away from the first square waveguide segment (51) and merges into the first composite segment (573). The first composite segment (573) continues to extend axially in a direction away from the first square waveguide segment (51) to form a left-handed output waveguide port (574). The left-handed composite waveguide (57) is connected to the left-handed output port (6) through the left-handed output waveguide port (574). The right-handed composite waveguide (58) includes a third connecting waveguide segment (581), a fourth connecting waveguide segment (582), a second composite segment (583), and a right-handed output waveguide port (584). The third coupling arm (55) is connected to the third connecting waveguide segment (581), and the fourth coupling arm (56) is connected to the fourth connecting waveguide segment (582).The third connecting waveguide segment (581) and the fourth connecting waveguide segment (582) are solid structures arranged around the center of the orthogonal mode coupler (5). They first extend axially in a direction away from the first waveguide segment (51), and then turn 90° before converging at the second synthesizing segment (583). The second synthesizing segment (583) continues to extend in a direction perpendicular to the axial direction to form a right-handed output waveguide port (584). The right-handed synthesizing waveguide (58) is connected to the right-handed output port (7) through the right-handed output waveguide port (584).

2. The feed source according to claim 1, characterized in that, The radiating horn (1) satisfies at least one of the following: The depth dimension of the annular groove formed by the choke corrugated horn (11) is 1 / 4λ to 1 / 2λ, where λ is the wavelength of the center frequency; The width of the annular groove formed by the choke corrugated horn (11) is 1 / 3λ~λ; The inner diameter of the second end of the output tapered section (14) is 5% to 20% larger than the inner diameter of the transmission circular waveguide (12); The inner diameter of the transmission circular waveguide (12) is controlled within the working transmission region of the main mode TE11 of the circular waveguide.

3. The feed source according to claim 1, characterized in that, The radiating horn (1) satisfies at least one of the following: The inner diameter of the circular waveguide section (131) should be controlled within the TE11 operating transmission region of the circular waveguide master mode; The side lengths of the first octagonal waveguide segment (132) are equal; The length of the first octagonal waveguide segment (132) in the axial direction ranges from 1 / 20λ to 1 / 10λ, where λ is the wavelength of the center frequency. The lengths of the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment (133) are greater than the lengths of the 1st, 3rd, 5th, and 7th sides of the first octagonal waveguide segment (132); The first, third, fifth, and seventh sides of the second octagonal waveguide segment (133) are of equal length, and the second, fourth, sixth, and eighth sides are of equal length. The second, fourth, sixth, and eighth sides of the second octagonal waveguide segment (133) are shorter than the first, third, fifth, and seventh sides of the second octagonal waveguide segment (133). The length of the second octagonal waveguide segment (133) in the axial direction ranges from 1 / 10λ to 1 / 4λ.

4. The feed source according to claim 1, characterized in that, The circular polarizer (2) satisfies at least one of the following: The length of each tooth in the polarization corrugated tooth (221) is different. Along the axis of the circular polarizer (2), the length of the polarization corrugated tooth (221) first decreases and then increases. The length of the polarized corrugated tooth (221) ranges from 1 / 30λ to 1 / 10λ, where λ is the wavelength of the center frequency. The depth of each tooth of the polarization corrugated tooth (221) is different. Along the axis of the circular polarizer (2), the depth of the polarization corrugated tooth (221) first increases and then decreases. The depth dimension of the polarized corrugated tooth (221) ranges from 1 / 10λ to 1 / 5λ; The spacing between two adjacent polarized corrugated teeth (221) is the same; The number of polarized corrugated teeth (221) is not less than 10 pairs; The output section (21) of the circular polarizer is a non-equilateral octagonal waveguide; the 1st, 3rd, 5th and 7th sides of the output section (21) of the circular polarizer are equilateral, the 2nd, 4th, 6th and 8th sides are equilateral, and the adjacent sides are unequal. The plane containing the 1st, 3rd, 5th, and 7th sides of the circular polarizer output segment (21) is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the second octagonal waveguide segment (133); The waveguide output terminal (223) is an equilateral quadrilateral waveguide; The waveguide transformation section (23) is a quadrilateral cavity structure with rounded corners.

5. The feed source according to claim 1, characterized in that, The octagonal inner cavity side length of the non-uniform octagonal waveguide (3) is the same as that of the output section (21) of the circular polarizer. The faces of the 1st, 3rd, 5th and 7th sides of the non-uniform octagonal waveguide (3) are coplanar with the faces of the 1st, 3rd, 5th and 7th sides of the output section (21) of the circular polarizer. The faces of the 2nd, 4th, 6th and 8th sides of the non-uniform octagonal waveguide (3) are coplanar with the faces of the 2nd, 4th, 6th and 8th sides of the output section (21) of the circular polarizer.

6. The feed source according to claim 1, characterized in that, The broadband 45° polarization rotator (4) satisfies at least one of the following: The side lengths of the non-equilateral octagonal waveguide (41) are equal for the 1st, 3rd, 5th and 7th sides, equal for the 2nd, 4th, 6th and 8th sides, and unequal for adjacent sides; The plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide (41) is coplanar with the plane containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide (3); The faces containing the 1st, 3rd, 5th, and 7th sides of the equilateral octagonal waveguide (42) are coplanar with the faces containing the 1st, 3rd, 5th, and 7th sides of the non-equilateral octagonal waveguide (41); The circumcircle diameter of the equilateral octagonal waveguide (42) is larger than the diameter of the circular waveguide (43); The radius of the inscribed circle of the non-equilateral octagonal waveguide (41) is the same as that of the inscribed circle of the equilateral octagonal waveguide (42).

7. The feed source according to claim 1, characterized in that, The inclined portions of the first coupling arm (53), the second coupling arm (54), the third coupling arm (55), and the fourth coupling arm (56) have the same inclination angle and the same inclination length; the inclined portions of the first coupling arm (53), the second coupling arm (54), the third coupling arm (55), and the fourth coupling arm (56) are evenly distributed around the central axis at 90°.

8. The feed source according to claim 1, characterized in that, The orthogonal mode coupler (5) satisfies at least one of the following: The inner side of the first connecting waveguide segment (571) and the inner side of the second connecting waveguide segment (572) each have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is not less than 3. The outer side of the first connecting waveguide segment (571) and the outer side of the second connecting waveguide segment (572) both have several impedance steps; the specific size of the impedance steps is determined by optimization, and the number of impedance steps is not less than 3.

9. The feed source according to claim 1, characterized in that, The orthogonal mode coupler (5) satisfies at least one of the following: The 90° turning section of the third connecting waveguide segment (581) and the 90° turning section of the fourth connecting waveguide segment (582) both have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is not less than 3. The outer side of the portion of the third connecting waveguide segment (581) extending in a direction perpendicular to the axial direction, and the outer side of the portion of the fourth connecting waveguide segment (582) extending in a direction perpendicular to the axial direction, both have several chamfered surfaces; the specific size of the chamfered surfaces is determined by optimization, and the number of chamfered surfaces is not less than 3. The inner side of the portion of the third connecting waveguide segment (581) extending in a direction perpendicular to the axial direction, and the inner side of the portion of the fourth connecting waveguide segment (582) extending in a direction perpendicular to the axial direction, both have several impedance steps; the specific impedance step size is determined by optimization, and the number of impedance steps is not less than 2.

10. The feed source according to claim 1, characterized in that, The left-hand output port (6) and the right-hand output port (7) are two standard waveguide to 2.92-K coaxial conversion ports, realizing the conversion of electromagnetic waves from waveguide transmission to coaxial transmission.

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