Millimeter wave antenna for low earth orbit satellite communications

Abstract

The application discloses a millimeter wave antenna for low-orbit satellite communication, which comprises a dielectric substrate, a first circular polarization radiator, seven conductor columns, a 90-degree circular arc, a second circular polarization radiator, a ground plane and a feed point. The dielectric substrate has four layers of conductors. The first circular polarization radiator is on the first layer and provides a first Ku-band mode and a first Ka-band mode. The seven conductor columns are vertically connected to the four layers of conductors and are uniformly arranged in a semicircular arc on the left side of the first circular polarization radiator. The 90-degree circular arc has a first center of circle, and a second end is connected to the first circular polarization radiator through a through hole, so that the polarization of the first Ku-band mode and the first Ka-band mode is right-handed. The second circular polarization radiator on the third layer is a truncated rectangular and provides a second Ku-band mode and a second Ka-band mode. The ground plane is on the fourth layer. The feed point is connected to the 90-degree circular arc and passes through the ground plane and the second circular polarization radiator through a through hole. The application provides dual-frequency right-handed circular polarization modes.

Description

TECHNICAL FIELD

[0001] The present application relates to a satellite communication antenna, in particular to a millimeter wave antenna for low earth orbit satellite communication. BACKGROUND

[0002] Now the mobile communication technology gradually develops in the direction of millimeter wave based on the demand of data transmission rate, using bandwidth and signal response ability, such as the fifth generation mobile communication (5G), which is mainly divided into two frequency sections, one of which is commonly called sub 5G application below 6GHz, and the other is millimeter wave frequency band, which provides huge data flow and higher information response ability. The operating frequency of millimeter wave is higher, the dielectric loss is higher, and the manufacturing precision of antenna module is also higher. Another technology using millimeter wave communication is low earth orbit satellite communication technology. Compared with the fifth generation mobile communication which needs to use the ground base station, low earth orbit satellite communication uses low earth orbit satellite above the ground, which is particularly beneficial to the application in remote areas, sea surface and other terrain limited areas. Low earth orbit satellite communication technology will be one of the most important communication technologies in the future, which has functions and advantages that traditional ground mobile communication technology cannot replace.

[0003] With the increasing powerful function of communication devices, the mobile communication device of user terminal is the most widely used product. In the case of limited size of mobile communication device, based on the continuous development of communication technology, the size requirement of antenna will inevitably become more and more strict, and for customers, smaller antenna design will make product design have more application flexibility and space, so as to improve the competitiveness of products. However, low earth orbit satellite communication uses circularly polarized electromagnetic wave signal. Compared with linearly polarized antenna, the size of circularly polarized antenna is usually larger. If multiple frequency bands of low earth orbit satellite communication are used, the miniaturization of circularly polarized antenna based on the bandwidth requirement is a more stringent test for antenna research and manufacturers. SUMMARY

[0004] In view of the above technical defects, the task of the present application is to provide a millimeter wave antenna for low earth orbit satellite communication, which can reduce the size of the antenna and meet the communication bandwidth requirement.

[0005] The technical scheme of the present application is as follows: a millimeter wave antenna for low earth orbit satellite communication, comprising:

[0006] The dielectric substrate has four layers of conductors, which are first layer, second layer, third layer and fourth layer in sequence;

[0007] a first circular polarized radiator in the first layer, the first circular polarized radiator is a conductor region remained after cutting a first circular disc with two parallel chords of same length and removing two cutting blocks outside the two parallel chords, the first circular polarized radiator is centered at a first center of the first circular disc, the first circular polarized radiator provides a first Ku-band mode and a first Ka-band mode;

[0008] seven conductor posts vertically penetrating the dielectric substrate and connecting the first layer, the second layer, the third layer and the fourth layer, the seven conductor posts are uniformly arranged in a half-arc left of the first circular polarized radiator with the first center as the center, a line connecting a first one and a last one of the seven conductor posts forms a 45-degree angle with the two parallel chords;

[0009] a 90-degree circular arc in the second layer and having a first end and a second end, the first end is right of the line connecting the first one and the last one of the seven conductor posts, the second end is above the line connecting the first one and the last one of the seven conductor posts, a line connecting the first end and the second end is parallel to the two parallel chords, the second end connects the first circular polarized radiator with a via hole, the 90-degree circular arc is used to make the polarizations of the first Ku-band mode and the first Ka-band mode both right-handed;

[0010] a second circular polarized radiator in the third layer and shaped as a truncated rectangle, the second circular polarized radiator provides a second Ku-band mode and a second Ka-band mode, a geometric center of the truncated rectangle is a projection of the first center on the third layer, short sides of the truncated rectangle are parallel to the two parallel chords, the truncated rectangle is truncated by right-angled triangles at a top right vertex and a top left vertex respectively;

[0011] a ground plane in the fourth layer; and

[0012] a feed point in the fourth layer, the feed point penetrates the ground plane and the second circular polarized radiator with a via hole and connects the first end of the 90-degree circular arc.

[0013] Further, a radius of the 90-degree circular arc is smaller than a radius of the first circular disc.

[0014] Further, frequency ranges of the first Ku-band mode and the second Ku-band mode are partially overlapped to increase circular polarization bandwidth, frequency ranges of the first Ka-band mode and the second Ka-band mode are partially overlapped to increase circular polarization bandwidth.

[0015] Further, projections of the first end and the second end on the first layer are located within the first circularly polarized radiator, and projections of the first end and the second end on the third layer are located within the second circularly polarized radiator.

[0016] Further, the two parallel chords include a right chord and a left chord, and the 90-degree circular arc crosses the right chord in a projection on the first layer.

[0017] Further, the right-angled triangle is an isosceles triangle with a 90-degree vertex, and a length of a leg of the isosceles triangle with a 90-degree vertex is less than a distance between a projection of the feed point on the third layer and the short side of the right side of the rectangle.

[0018] Further, the dielectric substrate has a first medium between the first layer and the second layer, a second medium between the second layer and the third layer, and a third medium between the third layer and the fourth layer, wherein a material of the first medium is roger ro4003 and a thickness of the first medium is 19.7 mil, wherein a material of the second medium is roger ro4450f and a thickness of the second medium is 11.8 mil, and wherein a material of the third medium is roger ro4003 and a thickness of the third medium is 19.7 mil.

[0019] Further, a radius of the first disc is 60 mil, a length of the two parallel chords is 102 mil, wherein a radius of the 90-degree circular arc is 45 mil, wherein lengths of the short side and the long side of the rectangle are 93 mil and 152 mil respectively, and wherein the right-angled triangle is an isosceles triangle with a 90-degree vertex, and a length of a leg of the isosceles triangle with a 90-degree vertex is 16.5 mil.

[0020] Further, the two parallel chords include a right chord and a left chord, and a distance between the projection of the feed point on the first layer and the right chord is 11 mil, wherein a distance between the projection of the feed point on the third layer and the short side of the rectangle is 45 mil, and a distance between the projection of the feed point on the third layer and the long side of the rectangle is 15 mil.

[0021] Further, a radius of the first disc determines a resonance frequency of the first Ku-band mode, the first Ku-band mode is a basic resonance mode of the first circularly polarized radiator, and the first Ka-band mode is a high-order mode of the first circularly polarized radiator, wherein a length of the long side of the rectangle determines a resonance frequency of the second Ku-band mode, and a length of the short side of the rectangle determines a resonance frequency of the second Ka-band mode.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] The present application is designed as a dual-frequency circularly polarized millimeter wave antenna. A first circularly polarized radiator is directly connected to a feed-in to generate dual-frequency and circularly polarized modes. A 90-degree circular arc feed-in is used to make the dual-frequency circularly polarized modes of the first circularly polarized radiator all right-handed. A second circularly polarized radiator is coupled to a feed-in to also provide dual-frequency right-handed circularly polarized modes. This dual-frequency antenna design has the advantages of reducing antenna area and providing a larger right-handed circularly polarized bandwidth, and only uses a single feed-in, which has very high industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of a first layer structure of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application.

[0025] Figure 2 is a schematic diagram of a second layer structure of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application.

[0026] Figure 3 is a schematic diagram of a third layer structure of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application.

[0027] Figure 4 is a schematic diagram of a fourth layer structure of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application.

[0028] Figure 5 is a curve graph of the S11 parameter of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application versus frequency change.

[0029] Figure 6 is a curve graph of the axial ratio of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application versus frequency change.

[0030] Figure 7 is a curve graph of the gain of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application versus frequency change.

[0031] Figure 8 is a curve graph of the efficiency of a low-orbit satellite communication millimeter wave antenna provided by an embodiment of the present application versus frequency change.

[0032] Figure 9 is a schematic diagram of a low-orbit satellite communication millimeter wave antenna fed by a coplanar waveguide provided by an embodiment of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with embodiments, but is not limited to the embodiments.

[0034] Reference should be made to Figures 1 to 4The embodiment of the present application provides a kind of millimeter wave antenna for low-orbit satellite communication, including dielectric substrate 1, first circular polarization radiator 2, seven conductor columns 3, a 90-degree circular arc 4, second circular polarization radiator 5, ground plane 6 and feed point 7.Dielectric substrate 1 has four layers of conductors, for example copper conductor, in order first layer 11, second layer 12, third layer 13 and fourth layer 14, the conductor structure of first layer 11 is as shown in Figure 1 , The conductor structure of second layer 12 is as shown in Figure 2 , The conductor structure of third layer 13 is as shown in Figure 3 , The conductor structure of fourth layer 14 is as shown in Figure 4 . First layer 11 and second layer 12 are first medium, second layer 12 and third layer 13 are second medium, third layer 13 and fourth layer 14 are third medium.First circular polarization radiator 2 is in first layer 11, first circular polarization radiator 2 is centered with the first center 200 of first disc 20, two parallel chords 21 of the same length are cut through first disc 20, and the remaining conductor area (represented by diagonal area) after removing two cutting blocks 210 (represented by dotted line in the figure) outside two parallel chords 21. The two parallel chords 21 are not only parallel to each other, but also the same length. First circular polarization radiator 2 provides first Ku band mode and first Ka band mode. First circular polarization radiator 2 uses two parallel chords 21 to cut first disc 20 to generate circularly polarized resonance mode. The radius length of first disc 20 determines the resonance frequency of first Ku band mode, first Ku band mode is the basic resonance mode of first circular polarization radiator 2, and first Ka band mode is the high-order mode of first circular polarization radiator 2. The Ku band (or frequency band) is a lower frequency band of 17.3GHz to 20.2GHz, and the Ka band is a higher frequency band of 27.5GHz to 30GHz. In addition, the feed point 7 is also shown in Figure 1 , The conductor of the through hole is not conductive with first circular polarization radiator 2, which will be described later.

[0035] Seven conductor columns 3 vertically penetrate dielectric substrate 1, and connect first layer 11, second layer 12, third layer 13 and fourth layer 14. Seven conductor columns 3 are uniformly arranged in the left semicircle of first circular polarization radiator 2 with the first center 200 as the center, and the angle between the connecting line of the first and last of the seven conductor columns 3 and the two parallel chords 21 is 45 degrees. In Figure 1 , Seven conductor columns 3 are in the left semicircle, and first circular polarization radiator 2 presents an angle of 45 degrees to the left based on two parallel chords 21. Seven conductor columns 3 are used to adjust the offset of the radiation field type, so that the radiation direction is perpendicular to dielectric substrate 1, to meet the application requirements of satellite communication.

[0036] 90-degree circular arc 4 is in the second layer 12 and the center of the 90-degree circular arc 4 is the projection of the first center 200 in the second layer 12, having a first end 41 and a second end 42, the first end 41 is on the right side of the line connecting the first and the last of the seven conductor posts 3, and the second end 42 is above the line connecting the first and the last of the seven conductor posts 3, wherein the line connecting the first end 41 and the second end 42 is parallel to the two parallel chords 21, the second end 42 is connected to the first circular polarized radiator 2 by a via hole, and the first end 41 is a via hole conductor directly connected to the feed point 7. The 90-degree circular arc 4 is used to make the polarization of the first Ku-band mode and the first Ka-band mode both right-handed. The line width of the 90-degree circular arc 4 is not limited, for example, about 5 mils is preferred, and slightly increasing or decreasing the width does not greatly affect the circular polarization characteristics. In the present embodiment, preferably, the radius of the 90-degree circular arc 4 is smaller than the radius of the first circular disk 20. In the present embodiment, preferably, the two parallel chords 21 include a right side chord and a left side chord, and the projection of the 90-degree circular arc 4 on the first layer 11 crosses the right side chord, but is not limited thereto. In the present embodiment, preferably, the two parallel chords 21 include a right side chord and a left side chord, and the projection of the 90-degree circular arc 4 on the first layer 11 crosses the right side chord, but is not limited thereto. Figure 2 In the present embodiment, the 90-degree circular arc 4 is a quarter circular arc present in the upper right region.

[0037] The second circular polarized radiator 5 is in the third layer 13 and has the shape of a truncated rectangular, providing the second Ku-band mode and the second Ka-band mode. The way of truncating the rectangular to generate circular polarization is to select two opposite corners of the four corners and cut off a pair of small areas of the same size at the two opposite corners. The geometric center 500 of the rectangular is the projection of the first center 200 in the third layer 13, wherein the short side 51 of the rectangular is parallel to the two parallel chords 21, and a right-angled triangle is used to truncate the rectangular at the top point 501 on the right side and the top point 502 on the left side, respectively. The right-angled triangle is, for example, an isosceles triangle with a 90-degree top angle. Using an isosceles triangle with a 90-degree top angle as the truncation of the rectangular is to simplify the adjustment of the parameters of the circular polarization characteristics. Other similar ways of truncation can also achieve the same effect, and the shape of the truncation is not limited. In the present embodiment, the top point where the short side 51 on the right upper side and the long side 52 on the right lower side are connected is referred to as the right top point, and the top point where the short side 51 on the left lower side and the long side 52 on the left upper side are connected is referred to as the left top point. The two top points are truncated by isosceles triangles with a 90-degree top angle, respectively. Therefore, the second circular polarized radiator 5 is a truncated rectangular using two isosceles triangles with a 90-degree top angle to generate the resonant mode of circular polarization. Referring to Figure 3, the feed point 7 is coupled in by a via hole passing through but not contacting the second circular polarized radiator 5, so that both the second Ku-band mode and the second Ka-band mode are right-hand circularly polarized. The length of the long side 52 of the rectangle determines the resonant frequency of the second Ku-band mode, and the length of the short side 51 of the rectangle determines the resonant frequency of the second Ka-band mode. In terms of structure, in the figure of the present embodiment, the length of the leg of the isosceles triangle with a 90-degree vertex angle is less than the distance from the projection of the feed point 7 on the third layer 13 (i.e. the via hole of the feed point 7) to the short side 51 on the right side of the rectangle.

[0038] The ground plane 6 is on the fourth layer 14. The feed point 7 is on the fourth layer 14, and the feed point 7 passes through the ground plane 6 of the fourth layer 14 and the second circular polarized radiator 5 of the third layer 13 by a via hole, and connects the first end 41 of the 90-degree circular arc 4 of the second layer 12. The detailed coupling-in manner of the feed point 7 by a via hole is explained as follows: the feed point 7 passes through the ground plane 6 and the second circular polarized radiator 5 by a via hole, and passes through the first end 41 of the 90-degree circular arc 4 to connect the second end 41 of the 90-degree circular arc 4 to the first circular polarized radiator 2, so that the first circular polarized radiator 2 is directly coupled in. As for the second circular polarized radiator 5, the conductor of the via hole of the feed point 7 forms a ring gap by passing through the third layer 13, so as to be coupled in in a capacitive manner. In addition, the via hole of the feed point 7 can form a through hole (as shown) in the first circular polarized radiator 2 of the first layer 11, but this through hole in the first layer 11 is not useful; if the through hole is not to be formed in the first layer 11, so that the conductor at the projection position of the feed point 7 is flat, then a buried hole process technology (so that there is no via hole between the first layer 11 and the second layer 12) needs to be used, and both of them do not affect the antenna characteristics. Figure 1

[0039] ​Further, based on the situation that the line connecting the first end 41 and the second end 42 of the 90-degree circular arc 4 is parallel to the two parallel chords 21, wherein the projection of the first end 41 and the second end 42 of the 90-degree circular arc 4 on the first layer 11 is located within the first circularly polarized radiator 2, and the projection of the first end 41 and the second end 42 of the 90-degree circular arc 4 on the third layer 13 is also located within the second circularly polarized radiator 5. Importantly, the second end 42 serves as a connection feed point of the first circularly polarized radiator 2, so that the first Ka-band mode as a high-order mode is a right-hand polarized mode. For the first Ku-band mode as a basic mode, if there is no path of the 90-degree circular arc 4, and a through-hole is directly fed at the position of the second end 42, then the first Ku-band mode as a lower frequency mode is a left-hand polarized mode. In fact, if the first Ka-band mode as a high-order mode is not considered, and only the first Ku-band mode as a lower frequency mode is required to be right-hand polarized, then a through-hole is directly fed at the position of the first end 41, and the 90-degree circular arc 4 is not used (in this case, the first end 41 is directly fed, and the first Ka-band mode as a high-order mode is left-hand polarized). Using this feeding method of the 90-degree circular arc 4, for the first Ku-band mode as a lower frequency mode, the result of right-hand polarized mode can also be achieved, and the first Ka-band mode as a high-order mode is right-hand polarized. In other words, the 90-degree circular arc 4 is used to make the polarization of the first Ku-band mode and the first Ka-band mode both right-hand.

[0040] As shown in the above antenna structure, the projections of the center of the seven conductor posts 3, the center of the 90° arc 4, and the geometric center 500 of the second circularly polarized radiator 5 on the first layer 11 all coincide with the first center 200 of the first circularly polarized radiator 2, thus forming a vertical stack structure. The shapes in the figures are not completely to scale and are only for illustration. In terms of the detailed dimensions of the antenna structure, the thickness of each layer of conductors is 0.7 mils, and there are three layers of dielectric, with the first layer of roger ro4003 having a thickness of 19.7 mils, the second layer of roger ro4450f having a thickness of 11.8 mils, and the third layer of roger ro4003 having a thickness of 19.7 mils. The radius of the first disk 20 is 60 mils, the length of the two parallel chords 21 is 102 mils, and the distance between the projection of the feed point 7 on the first layer 11 and the nearest parallel chord 21 (the right-hand chord) is 11 mils. The radius of the 90° arc 4 is 45 mils. The length of the short side 51 and the long side 52 of the rectangle is 93 mils and 152 mils, respectively. The length of the short side 51 and the long side 52 here is the length before the corners are truncated, and the length of the leg of the isosceles triangle with a top angle of 90° is 16.5 mils. Furthermore, the distance between the projection of the feed point 7 on the third layer 13 and the short side 51 of the rectangle is 45 mils, and the distance between the projection of the feed point 7 on the third layer 13 and the long side 52 of the rectangle is 15 mils. The feed point 7 is positioned so that the impedance value is close to 50 ohms, and the right-handed polarized mode is excited.

[0041] Please refer to Figure 5 , the curve CPW is the characteristic of the above antenna structure, and the curve CPWG is the co-planar waveguide of the structure shown in Figure 9 . The frequency ranges of the first Ku-band mode and the second Ku-band mode partially overlap to increase the circularly polarized bandwidth, and the Ku-band modes in Figure 5 are very close and almost completely overlap, so the mode curves appear to be a single mode. The frequency ranges of the first Ka-band mode and the second Ka-band mode partially overlap to increase the circularly polarized bandwidth. In the case of the curve CPWG, the Ka-band in Figure 5 clearly shows two modes, with the lower-frequency mode being generated by the first circularly polarized radiator 2 and the higher-frequency mode being generated by the second circularly polarized radiator 5. Similarly, in the case of the curve CPW, the overlapping modes can also be seen. In the desired frequency range, please refer to the curve CPW in Figures 5 to 8 , the S11 parameter of the applied frequency can reach -10 dB. Please refer to Figure 6 , the axial ratio in the desired frequency range is below 3 (dB). Furthermore, please refer to Figure 7 and Figure 8 , this antenna has good gain and antenna efficiency.Figure 9 All structures are represented by the first layer L1, the second layer L2, the third layer L3 and the ground layer GND. In actual production, the connection mode of the feed point affects the performance of the antenna product. If a connector is used to directly feed under the ground plane of the fourth layer 14, as long as the ground plane is large enough, the performance of the original design parameters of the antenna (such as directivity or radiation field direction) is not affected, and Figure 9 The curve CPWG represents the antenna characteristics of the coplanar waveguide feed. This feed mode is easy to apply to the case where the antenna substrate and the circuit board are shared or assembled together. In Figures 5 to 8 The curve CPWG represents the antenna characteristics of the coplanar waveguide feed. This feed mode is easy to apply to the case where the antenna substrate and the circuit board are shared or assembled together. In

[0042] In summary, the millimeter wave antenna for low-orbit satellite communication provided by the embodiment of the present application is a dual-frequency circularly polarized millimeter wave antenna. The first circularly polarized radiator is directly connected and fed to generate dual-frequency circularly polarized modes. The 90-degree circular arc feed mode makes the dual-frequency circularly polarized modes of the first circularly polarized radiator all right-handed. The second circularly polarized radiator is coupled and fed to also provide dual-frequency right-handed circularly polarized modes. This dual-frequency antenna design has the advantages of reducing the antenna area and providing a larger right-handed circularly polarized bandwidth, and only uses a single feed, which has high industrial application value.

Claims

1. A millimeter-wave antenna for low-Earth orbit satellite communication, characterized in that, include: The dielectric substrate has four conductor layers, which are, in order, the first layer, the second layer, the third layer and the fourth layer; The first circularly polarized radiator, in the first layer, is a conductor region remaining after cutting the first disk with two parallel chords of the same length, centered on the first center of the first disk, and removing the two blocks outside the two parallel chords, to provide a first Ku-band mode and a first Ka-band mode. Seven conductor pillars are vertically penetrating the dielectric substrate and connecting the first layer, the second layer, the third layer and the fourth layer. The seven conductor pillars are evenly arranged on the left half-circle arc of the first circularly polarized radiator with the first circle center as the center. The line connecting the first and last of the seven conductor pillars forms an angle of 45 degrees with the two parallel chords. A 90-degree arc, located in the second layer, with the center of the 90-degree arc being the projection of the first center onto the second layer, has a first end and a second end. The first end is to the right of the line connecting the first and last of the seven conductor pillars, and the second end is above the line connecting the first and last of the seven conductor pillars. The line connecting the first end and the second end is parallel to the two parallel chords. The second end is connected to the first circularly polarized radiator via a through hole. The 90-degree arc is used to make the polarization of both the first Ku-band mode and the first Ka-band mode right-handed. A second circularly polarized radiator, located in the third layer and shaped as a truncated rectangle, provides a second Ku-band mode and a second Ka-band mode. The geometric center of the rectangle is the projection of the first circle center onto the third layer. The short side of the rectangle is parallel to the two parallel chords. The rectangle is truncated at right-angled triangles at its right and left vertices, respectively. The ground surface is located on the fourth layer; as well as The feed point, located in the fourth layer, passes through the ground plane and the second circularly polarized radiator via a through-hole, and connects to the first end of the 90-degree arc.

2. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The radius of the 90-degree arc is smaller than the radius of the first disk.

3. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The frequency ranges of the first Ku-band mode and the second Ku-band mode partially overlap to increase the circular polarization bandwidth, and the frequency ranges of the first Ka-band mode and the second Ka-band mode partially overlap to increase the circular polarization bandwidth.

4. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The projections of the first end and the second end on the first layer are located within the first circularly polarized radiator, and the projections of the first end and the second end on the third layer are located within the second circularly polarized radiator.

5. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The two parallel chords include a right chord and a left chord, and the projection of the 90-degree arc on the first layer crosses the right chord.

6. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The right triangle is an isosceles triangle with a vertex angle of 90 degrees. The length of the leg of the isosceles triangle with a vertex angle of 90 degrees is less than the distance between the projection of the feed point on the third layer and the short side of the right side of the rectangle.

7. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The dielectric substrate has a first dielectric between the first layer and the second layer, a second dielectric between the second layer and the third layer, and a third dielectric between the third layer and the fourth layer, wherein the first dielectric is made of Roger Ro4003 and has a thickness of 19.7 mil, the second dielectric is made of Roger Ro4450F and has a thickness of 11.8 mil, and the third dielectric is made of Roger Ro4003 and has a thickness of 19.7 mil.

8. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The radius of the first disk is 60 millimeters, the length of the two parallel chords is 102 millimeters, the radius of the 90-degree arc is 45 millimeters, the lengths of the short side and the long side of the rectangle are 93 millimeters and 152 millimeters respectively, the right triangle is an isosceles triangle with a vertex angle of 90 degrees, and the length of the leg of the isosceles triangle with a vertex angle of 90 degrees is 16.5 millimeters.

9. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The two parallel chords include a right chord and a left chord. The distance between the projection of the feed point on the first layer and the right chord is 11 millimeters. The distance between the projection of the feed point on the third layer and the short side of the rectangle is 45 millimeters, and the distance between the projection of the feed point on the third layer and the long side of the rectangle is 15 millimeters.

10. The millimeter-wave antenna for low-Earth orbit satellite communication according to claim 1, characterized in that, The radius of the first disk determines the resonant frequency of the first Ku-band mode. The first Ku-band mode is the fundamental resonant mode of the first circularly polarized radiator. The first Ka-band mode is a higher-order mode of the first circularly polarized radiator. The length of the long side of the rectangle determines the resonant frequency of the second Ku-band mode. The length of the short side of the rectangle determines the resonant frequency of the second Ka-band mode.

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