A K / Ka band broadband dual circularly polarized antenna for low-orbit satellite communications

Abstract

The present invention relates to the field of wireless communications technology and discloses a K / Ka-band broadband dual-circularly polarized antenna for low-orbit satellite communications. The key technical aspects of the antenna include: a radiating aperture, a resonant cavity, a dual circular polarizer, a quasi-TEM transmission air cavity layer, a left-polarized broadband feed network layer, a right-polarized broadband feed network layer, a TEM mode conversion terminal, a polarization switch, a transceiver duplexer, a first standard waveguide port layer, and a second standard waveguide port layer. The antenna has a simple structure and self-packaging properties, offering excellent electromagnetic compatibility and high gain, wide bandwidth, and high circular polarization purity. A shielded air cavity is formed by stacking structures and metallized through-holes. When multiple circuits are integrated, mutual interference is minimized, resulting in a compact structure, easy assembly, and excellent electrical performance.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and more particularly, to a K / Ka frequency band broadband dual circular polarization antenna for low-orbit satellite communications. Background Art

[0002] The use of circular polarization and co-aperture design in existing technologies usually increases the complexity of the antenna system. For antenna arrays, improving the overall gain of the antenna requires increasing the aperture or number of co-aperture units. Due to the low-profile characteristics of microstrip antennas, this type of antenna is generally chosen for design.

[0003] However, when microstrip antennas are arrayed, there are problems such as narrow antenna bandwidth, low working efficiency, and complex structure; especially when meeting the requirements of broadband dual circular polarization, the feeding network design is complex, which is not conducive to the design, processing and adjustment of the overall antenna.

[0004] Therefore, the present invention provides a low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna, which improves the above technical problems. Summary of the Invention

[0005] The disclosed embodiments address the shortcomings of existing technologies by providing a broadband dual-circularly polarized antenna for low-orbit satellite communications in the K / Ka bands. This invention features a simple structure, self-encapsulation, and excellent electromagnetic compatibility, achieving high gain, wide bandwidth, and high circular polarization purity. By utilizing stacked structures and metallized through-holes to form a shielded air cavity, multiple circuits are integrated together with minimal mutual interference, resulting in a compact structure, easy assembly, and excellent electrical performance.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: a low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna unit, comprising: a radiation aperture, a resonant cavity, a dual circular polarizer, a quasi-TEM transmission air cavity layer, a left-polarized broadband feed network layer, a right-polarized broadband feed network layer, a TEM mode conversion terminal, a polarization switch, a transceiver duplexer, a first standard waveguide port layer, and a second standard waveguide port layer;

[0007] The radiation aperture is formed by an array of 8×8 unit groups. An isolation metal grid is provided inside the radiation aperture of each unit group. The isolation metal grid divides the radiation aperture into four horn ports to improve the directivity coefficient of the antenna.

[0008] The radiation port is located in a resonant cavity, and the resonant cavity is used to improve impedance matching;

[0009] A dual circular polarizer is provided below the resonant cavity. The dual circular polarizer is formed into an array of 8×8 unit groups. Each dual circular polarizer consists of two input ports and one output port. The input end consists of two identical rectangular waveguide ports, and the output end is a square waveguide.

[0010] A quasi-TEM transmission air cavity layer is provided below the dual circular polarizer, and a left-polarization broadband feeding network layer is provided below the quasi-TEM transmission air cavity layer; the quasi-TEM transmission air cavity layer and the left-polarization broadband feeding network layer are connected via a plurality of TEM mode conversion terminals; a first standard waveguide port layer is installed below the left-polarization broadband feeding network layer; a right-polarization broadband feeding network layer is provided below the first standard waveguide port layer; the first standard waveguide port layer and the right-polarization broadband feeding network layer are connected via a plurality of TEM mode conversion terminals; a second standard waveguide port layer is installed below the right-polarization broadband feeding network layer;

[0011] Polarization switches are provided on the upper surfaces of the left-polarized broadband feeding network layer and the right-polarized broadband feeding network layer;

[0012] Transceiver duplexers are provided on the upper surfaces of the first standard waveguide port layer and the second standard waveguide port layer.

[0013] As a preferred technical solution of the present invention, a metal isolation plate is installed on the inner surface of each dual circular polarizer; the dual circular polarizer can generate linear polarization or circular polarization with an arbitrary tilt angle by exciting two input ports through the metal isolation plate and at the same time with an appropriate phase relationship.

[0014] As a preferred technical solution of the present invention, the TEM mode conversion terminal is used to complete mode conversion. When the TEM mode conversion terminal has a quasi-coaxial structure, different inner diameters are adopted at both ends of the TEM mode conversion terminal, and a quasi-TEM transmission air cavity is used to meet the change in antenna standing wave caused by impedance change during the mode conversion process, introduce additional transmission loss, and ensure the purity of electromagnetic waves transmitted inside the cavity.

[0015] As a preferred technical solution of the present invention, the isolation metal grid divides the radiation port into four horn ports. The horn ports adopt a stepped horn plus a cross grid structure. By adjusting the size and height of the port surface of each step of the stepped horn, the impedance matching of the horn antenna can be achieved. The size and length of the waveguide correspond to the wave impedance of the guided mode. The calculation formula is as follows:

[0016]

[0017]

[0018] Among them, E u 、E vTransverse electric field; H u 、H v Transverse magnetic field; ε and μ are the dielectric constant and magnetic permeability of the medium respectively; ω is the angular frequency; β and κ are variable constants; λ and λ are c are the operating wavelength and cut-off wavelength respectively; is the inherent impedance of the medium, and the air impedance

[0019] As a preferred technical solution of the present invention, the radiation aperture is composed of an array of 8×8 units. The conditions for the array to not have grating lobes are:

[0020]

[0021] Where d is the spacing between the unit antennas, λ is the wavelength in free space corresponding to the antenna operating frequency, and θ is the scanning angle of the antenna;

[0022] When the antenna is not scanning, θ = 0, and the condition for no grating lobe to appear is:

[0023] d<λ

[0024] The radiation aperture of the square antenna satisfies the following conditions for wave transmission:

[0025] λ<2L

[0026] Where L is the length of the radiation port.

[0027] As a preferred technical solution of the present invention, the calculation formula for the power reflected back to the input port of the dual circular polarizer and the power coupled to the non-excited input port is:

[0028]

[0029] The relative amplitude and phase determine the axial ratio and the calculation formula of the principal axis inclination of the elliptically polarized wave:

[0030]

[0031]

[0032] Where Γ is the reflection coefficient of odd mode excitation, b i (i=1) represents the power reflected back to the input port, b i (i=2) indicates power coupled to the non-excitation input; b i (i=3) and b i The relative amplitude and phase of (i=4) determine the axial ratio and the major axis tilt angle of the elliptically polarized wave.

[0033] In summary, the present invention has the following beneficial effects:

[0034] First, wide bandwidth. The novel combination of a SISL feed network and a metal cavity ensures the antenna can operate normally within the K / Ka band. Good impedance matching within the K / Ka band ensures mode purity and further reduces antenna efficiency and gain reductions caused by impedance mismatch.

[0035] Second, it boasts a high level of integration. The advanced feed network structure allows for diverse and flexible input and output interfaces, including standard waveguide ports, coaxial ports, or direct connections to TR components. This provides strong adaptability, allowing both passive and active circuits to be designed simultaneously on the structure, achieving system integration and a high level of integration.

[0036] Third, it has a small size and compact structure. Miniaturization issues are addressed through loading and stacking. When integrated with other circuit systems, some circuits can be placed at the bottom or top of a multi-layer substrate, making the overall structure even more compact.

[0037] Fourth, easy assembly. The main structure of the antenna array is a lightweight alloy structure, which is assembled and installed by stacking and loading. There is no need for welding or debugging, making assembly simple and easy.

[0038] Fifth, excellent electrical performance. The novel antenna structure of the present invention enables the antenna to operate normally within the K / Ka frequency band. The antenna unit and its array have low axial ratio, sidelobe, and cross-polarization, while maintaining high aperture efficiency across the entire frequency band.

[0039] Sixth, it has a large power handling capacity. Due to the novel combination of the SISL feeding network and the metal cavity, the antenna electromagnetic wave is transmitted in the cavity as a quasi-TEM mode. The energy is confined inside the cavity and transmitted along the metal microstrip line and the cavity in the form of a quasi-TEM mode. The power handling capacity is comparable to that of a conventional rectangular waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A three-dimensional exploded diagram of the internal structure of a K / Ka-band broadband dual circularly polarized antenna for low-orbit satellite communications provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of a partial structure provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of a four-terminal network structure provided by an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of the partial structure of the radiation aperture and dual circular polarizer provided in an embodiment of the present invention;

[0044] Figure 5A schematic diagram of the local structure of a quasi-TEM transmission air cavity layer provided in an embodiment of the present invention;

[0045] In the figure: radiation aperture 1, resonant cavity 2, dual circular polarizer 3, quasi-TEM transmission air cavity layer 4, left-polarization broadband feed network layer 5, right-polarization broadband feed network layer 6, TEM mode conversion terminal 7, polarization switch 8, transceiver duplexer 9, first standard waveguide port layer 10, second standard waveguide port layer 11. DETAILED DESCRIPTION

[0046] The present application is described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but are not intended to limit the present application in any form. It should be noted that those skilled in the art may make several variations and improvements without departing from the scope of the present application. These all fall within the scope of protection of the present application.

[0047] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0048] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other and are all within the scope of protection of the present application. In addition, although the functional modules are divided in the device schematic and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order than the module division in the device or the order in the flow chart. In addition, the words "first", "second", "third", etc. used herein do not limit the data and execution order, but only distinguish between the same items or similar items with basically the same functions and effects.

[0049] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0050] In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0051] The embodiments disclosed herein are intended to solve the problems of narrow antenna bandwidth, low working efficiency, and complex structure when the microstrip antennas in the prior art are arrayed; in particular, the feeding network design is complex under the demand for broadband dual circular polarization, which is not conducive to the design, processing and commissioning of the overall antenna. In view of this, the embodiments disclosed herein propose a low-orbit satellite communication K / Ka band broadband dual circular polarization antenna. The antenna has a simple structure and self-packaging characteristics, good electromagnetic compatibility, and can achieve high antenna gain, wide bandwidth, and high circular polarization purity. By utilizing structural stacking and metallized through-holes to form a shielded air cavity, when multiple circuits are integrated together, there is little mutual interference, a compact structure, easy assembly, and excellent electrical performance.

[0052] Please refer to Figure 1-2 , Figure 1-2 The schematic diagram of the structure of the K / Ka band broadband dual circularly polarized antenna for low-orbit satellite communications according to an embodiment of the present disclosure is shown. The antenna comprises: a radiation aperture 1, a resonant cavity 2, a dual circular polarizer 3, a quasi-TEM transmission air cavity layer 4, a left-polarized broadband feed network layer 5, a right-polarized broadband feed network layer 6, a TEM mode conversion terminal 7, a polarization switch 8, a transceiver duplexer 9, a first standard waveguide port layer 10, and a second standard waveguide port layer 11.

[0053] The radiation aperture 1 is formed into an array of 8×8 units (every 4 apertures form a unit in a square), forming a 64-unit array antenna; Figure 4 As shown, an isolation metal grid is provided in the radiation aperture 1 of each unit group. The isolation metal grid divides the radiation aperture 1 into four horn-shaped surfaces. The horn-shaped surfaces are used to improve the uniform distribution of current, thereby improving the current distribution and increasing the directivity coefficient of the antenna.

[0054] The radiation aperture 1 is located in the resonant cavity 2, which ensures good impedance matching of the antenna within the K / Ka frequency band, ensuring mode purity and further reducing the antenna efficiency and gain reduction caused by impedance mismatch;

[0055] A dual circular polarizer 3 is provided below the resonant cavity 2. The dual circular polarizer 3 is composed of an array of 8×8 unit groups. Each dual circular polarizer 3 consists of two input ports and one output port. The input end consists of two identical rectangular waveguide ports, and the output end is a square waveguide. Figure 4 As shown, a metal isolation plate is installed on the inner surface of each dual circular polarizer 3; the dual circular polarizer 3 can generate linear polarization or circular polarization with an arbitrary tilt angle by exciting the two input ports simultaneously with an appropriate phase relationship through the metal isolation plate, so that the broadband polarizer has the characteristics of wide bandwidth and low axial ratio.

[0056] A quasi-TEM transmission air cavity layer 4 is provided below the dual circular polarizer 3. Figure 5As shown, a left-polarization broadband feeding network layer 5 is provided below the quasi-TEM transmission air cavity layer 4; the quasi-TEM transmission air cavity layer 4 and the left-polarization broadband feeding network layer 5 are connected via a plurality of TEM mode conversion terminals 7; a first standard waveguide port layer 10 is installed below the left-polarization broadband feeding network layer 5; a right-polarization broadband feeding network layer 6 is provided below the first standard waveguide port layer 10; the first standard waveguide port layer 10 and the right-polarization broadband feeding network layer 6 are connected via a plurality of TEM mode conversion terminals 7; a second standard waveguide port layer 11 is installed below the right-polarization broadband feeding network layer 6;

[0057] The TEM mode conversion terminal 7 is used to perform mode conversion, i.e., quasi-TEM mode to TEM mode to TE01 / TE10 mode. When the TEM mode conversion terminal 7 is a quasi-coaxial structure, by using different inner diameters at both ends of the TEM mode conversion terminal 7 and cooperating with the quasi-TEM transmission air cavity layer 4, the TEM mode conversion terminal 7 can mitigate the changes in antenna standing waves caused by impedance changes during mode conversion, thereby introducing additional transmission losses. This ensures the purity of electromagnetic waves transmitted within the cavity (without introducing additional electromagnetic wave transmission forms in other modes).

[0058] Polarization switches 8 are provided on the upper surfaces of the left-polarized broadband feeding network layer 5 and the right-polarized broadband feeding network layer 6;

[0059] Transceiver duplexers 9 are provided on the upper surfaces of the first standard waveguide port layer 10 and the second standard waveguide port layer 11 .

[0060] After the antenna unit completes the impedance and polarization matching of the unit, it needs to cooperate with the 6-level left-polarized broadband feeding network and the right-polarized broadband feeding network to effectively transmit the antenna energy. The quasi-TEM transmission air cavity layer 4 forms a complete air cavity. The multi-level broadband network completes the coaxial waveguide TEM mode-quasi-TEM mode transmission air cavity conversion and outputs the signal, thereby completing the distribution of microwave energy; at the same time, it cooperates with the polarization switch 8 and the transceiver duplexer 9 to complete the signal division and switching. Finally, the standard waveguide port receives and transmits the signal.

[0061] The radiator of the unit antenna of the present invention adopts a stepped gradient horn plus a cross grid structure. By adjusting the size and height of the aperture of each step of the stepped horn, the impedance matching of the horn antenna can be achieved.

[0062] Specifically, the wave resistance of the guided mode corresponding to the waveguide size and length is calculated; the calculation formula is as follows:

[0063]

[0064]

[0065] Among them, E u 、E v Transverse electric field; H u、H v Transverse magnetic field; ε and μ are the dielectric constant and magnetic permeability of the medium respectively; ω is the angular frequency; β and κ are variable constants; λ and λ are c are the operating wavelength and cut-off wavelength respectively; is the inherent impedance of the medium, and the air impedance

[0066] According to the above formula, for the square array antenna of the present invention, the antenna radiates inside the radiation cavity and the matching condition is that the impedance transformation is matched from 50Ω to 376.7Ω.

[0067] The conditions for the array to not have grating lobes are:

[0068]

[0069] Where d is the spacing between the unit antennas, λ is the wavelength in free space corresponding to the antenna operating frequency (i.e., the antenna operating wavelength), and θ is the antenna scanning angle. When the antenna is not scanning, θ = 0, and the condition for no grating lobes to appear is:

[0070] d<λ

[0071] For the radiation aperture 1 of the square antenna of the present invention, the conditions for wave transmission are:

[0072] λ<2L

[0073] Where L is the length of the radiation aperture 1.

[0074] The circular polarizer of the present invention consists of two input ports and one output port. The input port is composed of two identical rectangular waveguide ports, and the output port is a square waveguide. By adding an additional metal isolation plate and simultaneously exciting the two input ports with an appropriate phase relationship, linear polarization or circular polarization with an arbitrary tilt angle can be generated. Figure 3 The four-terminal network shown establishes the relationship between the network parameters for the symmetry of the structure.

[0075] For this structure, the traveling wave inside the cavity can be described as a i and b i (where i = 1, 2, 3, 4), where a i and b i (where i=1, 2, 3, 4) the amplitudes of the incident and reflected waves.

[0076] When an even mode is excited in the rectangular waveguide region (i.e., a1 = a2 = 1, a3 = a4 = 0), the electric and magnetic field distributions in the upper and lower rectangular waveguides are identical, but the current phases in the side walls are opposite. Therefore, the metal slot located in the common wall between the two waveguides does not interfere with the field distribution in the waveguide. The direction of current flow in the conductor is fixed. Therefore, if the currents in the two conductors are in opposite directions, the current flow in the first conductor is opposite to that in the second conductor, that is, the phase difference is 180°, and the amplitude cancels out. In fact, the propagation of the even mode wave can transfer all the energy to the TE10 mode of the rectangular waveguide.

[0077] When the odd mode is excited in the rectangular waveguide region (i.e., a1 = 1, a2 = -1, a3 = a4 = 0), the upper and lower waveguides are inversely spaced compared to the even mode case. The current is distributed on the top and bottom surface sidewalls in the same direction as the groove on the lower sidewall, which causes field interference, resulting in mode coupling and reflection. Therefore, the odd mode energy will be partially transferred to the TE01 mode in the square waveguide and partially;

[0078] Specifically, the power reflected back to the input port and the power coupled to the non-excited input port are calculated as follows:

[0079]

[0080] The relative amplitude and phase determine the axial ratio and the calculation formula of the principal axis inclination of the elliptically polarized wave:

[0081]

[0082]

[0083] Where Γ is the reflection coefficient of odd mode excitation, b i (i=1) represents the power reflected back to the input port (can also be expressed by the standing wave ratio VSWR), b i (i=2) indicates the power coupled to the non-excited input, which determines the isolation between ports. i (i=3) and b i The relative amplitude and phase of (i=4) determine the axial ratio and the major axis tilt angle of the elliptically polarized wave.

[0084] For a perfectly circularly polarized wave, b i (i=3) and b i (i=4) must have equal amplitude and a phase difference of 90°. Therefore, the essence of the design process is to find the minimum reflection coefficient of Γ in odd mode excitation, and the output phase angle is as close to 90° as possible.

[0085] The present invention verifies that an 8×8 unit group is composed of 64 unit array antennas. The array antenna can cover the K / Ka frequency band, has 4 ports for left and right transmission and reception (both K / Ka frequency bands have left and right rotation), the port standing waves are all within 1.5, the circular polarization axial ratio is less than 1.0, the antenna gain is greater than 26dB, and the port isolation is greater than 55dB. Among them, the left and right rotation input ports are a new form based on the combination of SISL feeding network and metal cavity, completing the TE01-quasi-TEM mode-TEM mode-TE01 / TE10 form conversion and energy transfer. In summary, the broadband dual circularly polarized antenna of the present invention has the characteristics of high gain, high efficiency and low axial ratio.

[0086] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna, characterized in that: include: Radiation port (1), resonant cavity (2), dual circular polarizer (3), quasi-TEM transmission air cavity layer (4), left polarization broadband feeding network layer (5), right polarization broadband feeding network layer (6), TEM mode conversion terminal (7), polarization switch (8), transceiver duplexer (9), first standard waveguide port layer (10), second standard waveguide port layer (11); The radiation aperture (1) is formed into an array of 8×8 unit groups, and an isolation metal grid is provided in the radiation aperture (1) of each unit group. The isolation metal grid divides the radiation aperture (1) into four horn ports, so as to improve the directivity coefficient of the antenna; The radiation port (1) is located in a resonant cavity (2), and the resonant cavity (2) is used to improve impedance matching; A dual circular polarizer (3) is provided below the resonant cavity (2), the dual circular polarizer (3) being formed into an array of 8×8 unit groups, each dual circular polarizer (3) being composed of two input ports and one output port, the input end being composed of two identical rectangular waveguide ports, and the output end being a square waveguide; A quasi-TEM transmission air cavity layer (4) is provided below the dual circular polarizer (3); a left-polarized broadband feeding network layer (5) is provided below the quasi-TEM transmission air cavity layer (4); the quasi-TEM transmission air cavity layer (4) and the left-polarized broadband feeding network layer (5) are connected via a plurality of TEM mode conversion terminals (7); a first standard waveguide port layer (10) is installed below the left-polarized broadband feeding network layer (5); a right-polarized broadband feeding network layer (6) is provided below the first standard waveguide port layer (10); the first standard waveguide port layer (10) and the right-polarized broadband feeding network layer (6) are connected via a plurality of TEM mode conversion terminals (7); a second standard waveguide port layer (11) is installed below the right-polarized broadband feeding network layer (6); Polarization switches (8) are provided on the upper surfaces of the left-polarized broadband feeding network layer (5) and the right-polarized broadband feeding network layer (6); Transceiver duplexers (9) are provided on the upper surfaces of the first standard waveguide port layer (10) and the second standard waveguide port layer (11).

2. The low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna according to claim 1, characterized in that: A metal isolation plate is installed on the inner surface of each dual circular polarizer (3); the dual circular polarizer (3) can generate linear polarization or circular polarization with an arbitrary tilt angle by exciting two input ports at the same time with an appropriate phase relationship through the metal isolation plate.

3. The low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna according to claim 1, characterized in that: The TEM mode conversion terminal (7) is used to complete mode conversion; when the TEM mode conversion terminal (7) is a quasi-coaxial structure, different inner diameters are used at both ends of the TEM mode conversion terminal (7), and a quasi-TEM transmission air cavity is used to meet the requirements of the change in antenna standing wave caused by impedance change during the mode conversion process, introducing additional transmission loss, and ensuring the purity of electromagnetic waves transmitted inside the cavity.

4. The low-orbit satellite communication K / Ka band broadband dual circularly polarized antenna according to claim 1, characterized in that: The isolation metal grid divides the radiation aperture (1) into four horn apertures, wherein the horn apertures adopt a stepped gradient horn plus a cross grid structure. By adjusting the aperture size and height of each step of the stepped horn, the impedance matching of the horn antenna can be achieved; wherein the size and length of the waveguide correspond to the wave impedance of the guided mode; the calculation formula is as follows: Among them, E u 、E v Transverse electric field; H u 、H v Transverse magnetic field; ε and μ are the dielectric constant and magnetic permeability of the medium respectively; ω is the angular frequency; β and κ are variable constants; λ and λ are c are the operating wavelength and cut-off wavelength respectively; is the inherent impedance of the medium, and the air impedance 5. The low-orbit satellite communication K / Ka band broadband dual circular polarization antenna according to claim 1, characterized in that: The radiation aperture (1) is composed of an array of 8×8 units. The condition for the array to not have grating lobes is: Where d is the spacing between the unit antennas, λ is the wavelength in free space corresponding to the antenna operating frequency, and θ is the scanning angle of the antenna; When the antenna is not scanning, θ = 0, and the condition for no grating lobe to appear is: d<λ The radiation aperture (1) satisfies the following conditions for wave transmission: λ<2L Where L is the length of the radiation port (1).

6. The low-orbit satellite communication K / Ka band broadband dual circular polarization antenna according to claim 1, characterized in that: The calculation formula of the power reflected back to the input port of the dual circular polarizer (3) and the power coupled to the non-excited input port is: The relative amplitude and phase determine the axial ratio and the calculation formula of the principal axis inclination of the elliptically polarized wave: Where Γ is the reflection coefficient of odd mode excitation, b i (i=1) represents the power reflected back to the input port, b i (i=2) indicates power coupled to the non-excitation input; b i (i=3) and b i The relative amplitude and phase of (i=4) determine the axial ratio and the major axis tilt angle of the elliptically polarized wave.

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