Switchable phased-array antenna applied to low-orbit satellite communication terminal

Abstract

The invention relates to a switchable phased-array antenna applied to a low-orbit satellite communication terminal, which comprises a plurality of antenna radiators, the longitudinal sections of unit directional diagrams of the switchable phased-array antenna at any position are in the same curve, and the curve shape is shown as follows: the radiation energy of the antenna at 0 DEG C is smaller, and the radiation energy of the antenna at 0 DEG C is smaller. The radiation energy of the antenna is the maximum at the angles of X degrees and-X degrees; a unit pattern with low radiation energy at the zenith and high radiation energy at a large angle is met; the unit pattern is changed by switching the antenna units. According to the antenna directional diagram, the requirement for a directional diagram pattern with low gain at the zenith and high gain when a large angle is scanned is met, only the phased-array antenna and the antenna unit of the terminal are changed, other hardware is not changed, existing mature technologies and modules can be used to the maximum extent on the basis of improving the performance of the phased-array antenna, and the cost is reduced. The complexity of batch production can be reduced, and the method has good engineering practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array antennas, and in particular to a switchable phased array antenna applied to a low-orbit satellite communication terminal. Background Art

[0002] In recent years, with the development of satellite communication technology, the continuous reduction of commercial space costs, and the development of new communication standards such as 5G+ and 6G, low-orbit satellite communication networks with the advantage of global coverage have begun to gain vigorous development. The low-orbit satellite communication industry has gradually become one of the new engines of the future communication industry, and it will be an important part of the future 6G network.

[0003] Low-orbit satellites mainly refer to satellites operating in low earth orbit (500-2000km from the ground, LE0). Compared with high-orbit (geostationary orbit, GE0) satellites, low-orbit satellites have the advantages of short distance, small transmission delay, low link loss, flexible launch, rich application scenarios, and low overall launch cost in communication applications. However, satellite communication has a long transmission distance and high technical difficulty. As a terminal of the low-orbit satellite communication system, its performance requirements are higher than those of mobile phones and other terminals, and its cost is higher and its technology is more complex. Therefore, it is of great significance to improve the communication capabilities of the terminal through innovative design.

[0004] At the same time, large-scale low-orbit satellite communication constellations are generally composed of satellite sub-constellations at various orbital altitudes. Taking the constellation planned by China Star Network as an example, in September 2020, China Star Network submitted a spectrum allocation file to the International Telecommunication Union (ITU). The file exposed two broadband constellation plans called GW-A59 and GW-2, with a total planned launch of 12,992 satellites. The "GW" constellation consists of a total of 2 sub-constellations, and the orbital altitudes are also divided into two groups. The satellites of the GW-A59 sub-constellation are distributed in an extremely low orbit of about 550km, and the satellites of the GW-2 sub-constellation are distributed in a low-Earth orbit of 1,145km. The orbital inclinations of the two groups of satellites are distributed between 30° and 85°.

[0005] An antenna is a device used to transmit and receive electromagnetic energy. Phased array antennas used for satellite communications generally require a combination of multiple antennas to form an array antenna to achieve beam scanning and other functions. For example, StarLink Dish has more than 1,300 antenna units in the entire phased array, which form a phased array antenna to transmit and receive satellite signals. There are four main factors that control the radiation pattern of the array antenna: unit radiation pattern, unit spacing, unit antenna feed amplitude, and unit antenna feed phase. The first item is related to the unit, and the last three items are all related to the array factor.

[0006] The performance of the phased array antenna commonly used now meets the following rules: when the phased array scans to 0°, the antenna gain is the highest, and when the phased array scans to 60°, the antenna gain is the lowest. According to engineering experience, the gain is about 5dB lower than that at 0°. The larger the scanning angle, the lower the gain, the smaller the signal strength, and the lower the communication rate.

[0007] The orbit of a low-orbit satellite is low and the satellite moves very fast. For a terminal, each connection with a satellite lasts only a dozen minutes. During these ten minutes, the terminal's beam needs to scan from 60° to -60°. The spatial loss in the same orbit will also change by several dB. At the same time, the gain capability of the terminal antenna relative to the strongest point will also change by about 5 dB. Assuming that the signal strength of the satellite transmission and reception remains unchanged, when the terminal's beam scans from 60° to -60°, the loss of the overall link relative to the strongest point of the signal will also change by nearly 10 dB. This is a very large fluctuation. Although a margin is reserved when designing the overall link to cope with changes in channel loss, the terminal rate of user communication will also change in a short period of time. In some scenarios with increased loss, such as rainy scenes, the signal loss is further increased when passing through humid air, and the spatial loss is also greater when scanning at a large angle. The superposition of the two will greatly affect the user experience. Even for some enterprise businesses that are sensitive to rate, bit error rate and reliability, there will be disconnection when scanning at a large angle, which will have an adverse impact on users. Summary of the invention

[0008] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a switchable phased array antenna for low-orbit satellite communication terminals. Only the phased array antenna and its antenna unit of the terminal are changed, and other hardware are not modified. On the basis of improving the performance of the phased array antenna, the existing mature technologies and modules can be used to the maximum extent, the complexity of mass production can be reduced, and it has good engineering practicality.

[0009] To achieve the above-mentioned object of the invention, the present invention provides a switchable phased array antenna applied to a low-orbit satellite communication terminal, comprising a plurality of antenna radiators, wherein the unit radiation pattern of the switchable phased array antenna presents the same curve in a longitudinal section at any position, and the shape of the curve is represented as follows: the radiation energy of the antenna is small at 0°, and the radiation energy of the antenna is maximum at angles of X° and -X°;

[0010] The unit pattern graphics satisfy the requirement of low radiation energy at the zenith and high radiation energy at large angles;

[0011] The element directivity pattern is changed by switching the antenna elements.

[0012] According to a technical solution of the present invention, on any longitudinal section of the unit directional pattern, from 0° to X°, the radiation energy of the unit directional pattern increases as the angle approaches X°;

[0013] When the angle exceeds X°, the radiation energy of the unit pattern decreases as the angle moves away from X°.

[0014] According to a technical solution of the present invention, on any longitudinal section of the unit directional pattern, from 0° to -X°, the radiation energy of the unit directional pattern increases as the angle approaches -X°;

[0015] When the angle exceeds -X°, the radiation energy of the unit pattern decreases as the angle moves away from -X°.

[0016] According to a technical solution of the present invention, it also includes:

[0017] A feed network for distributing signals to the various antenna radiators;

[0018] A receiving module for converting received electromagnetic waves into electrical signals;

[0019] Transmitter module used to convert electrical signals into electromagnetic waves.

[0020] According to a technical solution of the present invention, the switchable phased array antenna is configured with a switching switch for radiating an electromagnetic field of the antenna radiator.

[0021] According to a technical solution of the present invention, the switching switch is arranged inside the antenna radiator to change the radiation electromagnetic field of the antenna radiator.

[0022] According to a technical solution of the present invention, the switching switch is arranged at the feeding network to change the feeding amplitude or phase size of different feeding ports.

[0023] According to a technical solution of the present invention, the array pattern of the switchable phased array antenna = unit pattern * array factor.

[0024] According to a technical solution of the present invention, the value range of X is: 0≤X≤90.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention is different from conventional satellite communication phased array antennas. The directional pattern of the array antenna is innovatively designed to meet the low-orbit scenario requirements of low-orbit satellite communications. The innovatively designed antenna directional pattern meets the directional pattern graphics of low gain at the zenith and high gain when scanning at a large angle. Only the phased array antenna and antenna unit of the terminal are changed, and other hardware is not modified. On the basis of improving the performance of the phased array antenna, the existing mature technologies and modules can be used to the maximum extent, the complexity of mass production can be reduced, and it has good engineering practicality.

[0027] When the phased array is scanning, the distance is short and the loss is small when scanning to the zenith, and the distance is long and the loss is large when scanning to a large angle. The phased array antenna of the present invention can compensate for the loss when scanning to a certain angle, so that the overall loss of the communication link is equivalent. The overall loss is smaller than that of a conventional phased array antenna, which is beneficial to improving the performance of the communication system.

[0028] In the present invention, the directional pattern of the antenna can be switched by a switch to meet the needs of sub-constellations of different orbital altitudes of a large-scale constellation. For different orbital altitudes, the directional pattern can be switched to achieve different radiation energy intensities at the same angle to adapt to satellites at different orbital altitudes. When forming a phased array antenna, the array antenna has a low gain at the zenith and a high gain directional pattern when scanning at a large angle. Different gains at the same angle can be achieved by switching to meet the orbital altitudes of different satellites. At the same time, the directional pattern can ensure that the communication link loss at the same orbital altitude is roughly equivalent, which is beneficial to the consistency and stability of the communication system. This phased array antenna is suitable for large-scale low-orbit satellite communication constellations and giant constellations with a variety of different orbital altitudes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram showing the main lobe of the array antenna array factor scanning at different angles according to the conventional array antenna principle;

[0031] Figure 2 A schematic diagram showing a directional pattern of a conventional unit antenna based on the principle of a conventional array antenna;

[0032] Figure 3 A schematic diagram showing the gain and main lobe of a conventional array antenna when scanning at different angles;

[0033] FIG4(a) and FIG4(b) show the process of establishing communication with a satellite by changing the main lobe beam of the phased array antenna to point to the satellite when the satellite moves to a certain angle, wherein the communication link distances at different angles, such as 0°, 60°, and -60°, are illustrated;

[0034] Figure 5 A schematic diagram showing a unit radiation pattern of a switchable phased array antenna provided according to an implementation example of the present invention;

[0035] 6(a) and 6(b) are schematic diagrams showing a switching mode of a directional pattern of a unit antenna according to the present invention;

[0036] Figure 7 A schematic diagram showing the gain and main lobe of the phased array antenna scanned at different angles according to an implementation example of the present invention;

[0037] Figure 8 It represents a switchable directional pattern provided according to an implementation example of the present invention, and the curves of the directional pattern are different equations to meet different application scenarios;

[0038] Fig. 9 It represents an array antenna arrangement method provided according to an implementation example of the present invention;

[0039] Fig.10 A square array antenna pattern scanned at different angles is shown according to an embodiment of the present invention;

[0040] Fig.11 A square array antenna pattern scanned at different angles is shown according to another embodiment of the present invention;

[0041] Fig.12 A schematic diagram of overall link calculation of a phased array antenna scanned at different angles provided by an implementation case of the present invention, including antenna gain and space loss, is shown, and the satellite orbit is 550KM at this time;

[0042] Fig.13 A schematic diagram of overall link calculation of a phased array antenna scanned at different angles provided by an implementation case of the present invention, including antenna gain and space loss, is shown, and the satellite orbit is 1145KM at this time;

[0043] Fig.14 It represents the signal energy of the signal radiated by the satellite reaching the receiver after being received by the antenna when the satellite orbit provided by an implementation case of the present invention is 550KM;

[0044] Fig.15It indicates that when the satellite orbit provided by an implementation case of the present invention is 1145KM, the signal energy of the signal radiated by the satellite reaches the receiver after being received by the antenna. DETAILED DESCRIPTION

[0045] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0046] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0047] like Figure 1 As shown in Figure 4, taking a uniformly distributed linear array as an example, under far-field conditions, the electromagnetic wave propagates to the array surface in the form of a plane wave (the wavefront is an equiphase surface), the array element spacing of the linear array is d, the number of array elements is n, and the beam pointing angle is θ. According to the superposition principle, the directivity diagram of the array factor is:

[0048]

[0049] Among them, A n represents the amplitude weight of the nth unit, d n is the distance from the nth element to the reference point, k is the wave number, λ is the wavelength, and:

[0050]

[0051] By changing the beam index angle θ, the beam scanning of the array antenna can be achieved. Figure 1 The main lobe pattern at different scanning angles is shown in Figure 2. The radiation pattern of a conventional antenna unit is shown in Figure 2. Figure 2 As shown: the gain is the largest at the zenith, and the gain becomes smaller at a certain angle away from the zenith. The greater the deviation angle, the more the gain becomes smaller at a certain angle.

[0052] The pattern gain of the overall array is as follows: Figure 3 As shown: the phased array has the largest gain at 0°, and the antenna gain is lowest when the phased array scans to 60°. According to engineering experience, it is about 5dB lower than the gain at 0°. The larger the scanning angle, the lower the gain.

[0053] The radius of the earth is 6371 kilometers, and the orbital altitude of low-orbit satellite communication is 500-2000KM. The satellite phased array terminal on the earth has the ability to scan, generally with the ability to scan from +60° to -60°. Therefore, when the satellite appears at the 60° azimuth of the terminal's view, communication can begin. At the same time, the satellite moves in a circle around the earth until the satellite is at the -60° azimuth of the terminal's view. During this period of time, the terminal has been establishing a stable and reliable communication connection with the satellite until the satellite exceeds the -60° azimuth of the terminal's view. This is when the terminal controls its own beam and switches to the next satellite. The next satellite happens to appear at the 60° azimuth of the terminal's view at this time, and the communication service continues. This pattern repeats itself, and the satellite provides stable and reliable communication services to ground terminals through relay. In this process, the signal needs to be transmitted between the satellite and the terminal. The transmission distance changes with the angle between the satellite and the terminal, because the signal needs to pass through the atmosphere. In this process, the signal is lost. The amount of loss is inconsistent at different distances. The longer the distance, the greater the loss. Assuming that the satellite's transmission and receiving performance capabilities are fixed, the signal strength reaching the terminal is inconsistent at different angles. It is related to the angle between the terminal and the satellite. The larger the angle, the greater the signal loss, the lower the strength of the arriving signal, the worse the signal quality, and the slower the communication rate. The smaller the angle, the smaller the signal loss, the higher the strength of the arriving signal, the better the signal quality, and the faster the communication rate. The fastest point is the position with an angle of 0°.

[0054] Taking the satellite orbit of the GW-2 constellation as an example, as shown in Figure 4, its orbit altitude is 550km and 1145km low-Earth orbit, and the radius of the Earth is 6371 kilometers. When the satellite is at 0°, the distance between the satellite and the terminal is 550km and 1145km. When the satellite is at 60°, the corresponding distance between the satellite and the terminal is about 970km and 1900km. Therefore, when the satellite scans from 0° to 60° relative to the terminal, the distance between the satellite and the terminal increases from 550km to 970km, or from 1145km to 1900km.

[0055] Assuming that the operating frequency of the satellite and the terminal is around 20GHz, according to the classic transmission formula, when the distance between the satellite and the terminal is 550km, the space loss is 173dB, and when the distance is 970km, the space loss is 178.2dB, with a difference of 5.2dB. When the distance is 1145km, the space loss is 179.6dB, and when the distance is 1900km, the space loss is 184dB, with a difference of 4.4dB. When the satellite scans from 0° to 60° relative to the terminal, the space loss changes from 173dB to 178.2dB in the 550km orbit, and changes from 179.6dB to 184dB in the 1145km orbit.

[0056] Transmission formula: Space loss dB = 32.4 dB + 20*log (distance km) + 20*log (frequency MHz).

[0057] The ideal transmission scenario is that no matter what the relative angle between the satellite and the terminal in the same orbit is, the signal received by the terminal from the satellite should be of equal strength, which is convenient for the terminal to modulate and demodulate the signal later. With such an ideal signal, the terminal rate can remain unchanged, which can greatly improve the user experience and will not cause the user to be troubled by fluctuating rates.

[0058] like Figures 5 to 13 As shown, a switchable phased array antenna for a low-orbit satellite communication terminal provided by the present invention includes a plurality of antenna radiators (one antenna radiator can be regarded as corresponding to one antenna unit), and the unit radiation pattern of the switchable phased array antenna presents the same curve in the longitudinal section at any position, and the shape of the curve is represented as follows: the radiation energy of the antenna is small at 0°, and the radiation energy of the antenna is maximum at the angles of X° and -X°;

[0059] The unit pattern graphics satisfy the requirement of low radiation energy at the zenith and high radiation energy at large angles;

[0060] The element directivity pattern is changed by switching the antenna elements.

[0061] like Figure 5 As shown in the figure, the antenna pattern of the array has been innovatively designed to meet the low-orbit scenario requirements of low-orbit satellite communications. The antenna pattern of the innovative design meets the directional pattern of low gain at the zenith and high gain when scanning at a large angle. At the same time, the antenna pattern can be switched by a switch to meet the sub-constellations of different orbital altitudes of large-scale constellations.

[0062] Figure 5 In the figure, the longitudinal section of the unit radiation pattern at any position is represented. The complete diagram of the unit radiation pattern of the switchable phased array antenna can be regarded as: Figure 5 The figure in is obtained by rotating 360° around the center line of 0°.

[0063] The antenna unit radiation pattern satisfies the radiation pattern figure of low radiation energy at the zenith and high radiation energy at a large angle. When the phased array is scanning, the distance is short and the loss is small when scanning to the zenith, and the distance is long and the loss is large when scanning to a large angle. The phased array antenna of the present invention can compensate for the loss when scanning to a certain angle, so that the overall loss of the communication link is equivalent, and the overall loss is smaller than that of a conventional phased array antenna, which is beneficial to improving the performance of the communication system.

[0064] Furthermore, the present invention has a switching function, which changes the unit radiation pattern by switching the antenna unit. For different orbital altitudes, the radiation energy intensity at the same angle can be different by switching the radiation pattern, so as to adapt to satellites at different orbital altitudes. When forming a phased array antenna, the array antenna has a low gain at the zenith and a high gain radiation pattern when scanning at a large angle. It can achieve different gains at the same angle to meet the orbital altitudes of different satellites by switching. At the same time, the radiation pattern can ensure that the communication link loss at the same orbital altitude is roughly the same, which is beneficial to the consistency and stability of the communication system. At the same time, the phased array antenna of the present invention is suitable for large-scale low-orbit satellite communication constellations, and has a variety of giant constellations with different orbital altitudes.

[0065] In some embodiments of the present invention, on any longitudinal section of the unit pattern, from 0° to X°, the radiation energy of the unit pattern increases as the angle approaches X°;

[0066] When it exceeds X°, the radiation energy of the unit pattern decreases as the angle moves away from X°;

[0067] At 0° to -X°, the radiation energy of the unit pattern increases as the angle approaches -X°;

[0068] When the angle exceeds -X°, the radiation energy of the unit pattern decreases as the angle moves away from -X°.

[0069] like Figure 5 and Figure 8 As shown, the array antenna needs to scan to 60°, that is, X = 60. When the terminal is connected to the track at 550 km, Figure 5 As shown in the first curve, the radiation energy of the antenna is maximum when the antenna pattern is at 60° and -60°, and the corresponding gain is 2dB. When the antenna pattern is at 0°, the corresponding gain of the antenna is -3.2dB. When the terminal is connected to the track at 1145KM, Figure 5 As shown in the second curve in , the radiation energy of the antenna is the largest when the antenna pattern is at an angle of 60° and -60°, and the corresponding gain is 1.6dB. When the antenna pattern is at 0°, the corresponding gain of the antenna is -2.8dB. The two patterns are switched by a switch, and the rules are similar. When the angle is from 0° to 60°, the radiation energy of the pattern increases as the angle approaches 60°. When it exceeds 60°, the radiation energy of the pattern decreases as the angle moves away from 60°. When the angle is from 0° to -60°, the radiation energy of the pattern increases as the angle approaches -60°. When it exceeds -60°, the radiation energy of the pattern decreases as the angle moves away from -60°. The 3D graphics of the antenna are rotationally symmetric around the center line of 0°. The 3D graphics are cut with a vertical line passing through 0°. The 2D graphics of each cut are similar and all meet the variation rules of the radiation energy of the pattern.

[0070] For the curve equation of the variation law, the radiation energy that satisfies the directivity diagram increases as the angle approaches -60° and 60°. The present invention does not make any agreement on the specific equation.

[0071] like Figure 8 As shown, three possible equation forms are listed, which can be straight lines, such as Figure 8 As shown by the third line segment in , it can also be a curve equation, such as Figure 8 As shown in the fourth curve in , it can also be the concatenation of two curve equations, such as Figure 8 As shown in the fifth curve in FIG. , the curve equation of the present invention includes the following: Figure 8 The situations shown, but not limited to Figure 8 As shown; the curve of the equation can also be switched by a switch, and can be flexibly and adaptively adjusted according to different scenarios to improve the communication quality of the overall terminal.

[0072] In some embodiments of the present invention, the switchable phased array antenna of the present invention further includes:

[0073] A feed network for distributing signals to the various antenna radiators;

[0074] A receiving module for converting received electromagnetic waves into electrical signals;

[0075] Transmitter module used to convert electrical signals into electromagnetic waves.

[0076] In some embodiments of the present invention, the switchable phased array antenna is configured with a switch for the antenna radiator to radiate the electromagnetic field.

[0077] In some embodiments of the present invention, the switch is disposed between two adjacent antenna radiators to change the radiated electromagnetic field of the antenna radiators.

[0078] In some embodiments of the present invention, the switching switch is arranged at the feeding network to change the feeding amplitude or phase size of different feeding ports.

[0079] A switching switch is provided at the antenna radiator or the feeding network of the antenna, wherein the switching switch can be placed inside the antenna body, so as to realize the function that the unit antenna directional pattern can be switched.

[0080] FIG. 6( a ) is a schematic diagram showing a switch switching an antenna radiator, and FIG. 6( b ) is a schematic diagram showing a switch switching an antenna feed port.

[0081] As shown in FIG6(a), a switching switch is provided between antenna radiator 1 and antenna radiator 2, and a switching switch is provided between antenna radiator 3 and antenna radiator 4. The switching switch is a part of the antenna. The state of the switching switch can change the radiation electromagnetic field of the antenna radiator, thereby changing the radiation pattern of the antenna, so as to realize the switching function of the antenna pattern. At the same time, antenna radiator 1 and antenna radiator 3 are connected through a feeding network.

[0082] The switch can also be placed at the feed of the antenna, as shown in Figure 6(b). When the antenna has one or more feed ports, the antenna in the figure has two feed ports (feed 1 and feed 2). By switching the different feed ports of the antenna, the feeding amplitude or phase size of the different feed ports is changed, so that the radiation electromagnetic field of the antenna radiator changes, and then the radiation pattern of the antenna is changed to realize the switching function of the antenna pattern. The present invention does not make specific requirements on the number of antenna feed ports, the number of switches, and the number of switching states.

[0083] In some embodiments of the present invention, the array pattern of the switchable phased array antenna = unit pattern * array factor.

[0084] The array radiation pattern of the active phased array antenna of the present invention=unit radiation pattern*array factor Q.

[0085] The array factor is as follows Figure 1 In the conventional design shown in FIG. 1 , the array antenna scans at a certain section, and takes the same section of the 3D directional pattern. The array antenna of the present invention scans directional patterns at different angles as shown in FIG. Figure 7 As shown, the gain of the phased array is maximum when the array pattern is at X° and -X°, which is A*Q (where Q is equivalent to the radiation intensity of the array factor, and A is the unit radiation intensity, which can be changed in size by switching, and can be A1, A2, A2, etc.), and the gain of the phased array when the phased array pattern is 0° is B*Q (which can be B1, B2, B2, etc. by switching), from 0° to X°, the gain of the phased array pattern increases as the angle approaches X°, and when it exceeds X°, the gain of the pattern decreases as the angle moves away from X°, and from 0° to -X°, the gain of the pattern increases as the angle approaches -X°, and when it exceeds -X°, the gain of the pattern decreases as the angle moves away from -X°.

[0086] In addition, the angle X is related to the design scanning angle of the terminal product, and the value range can be set to 0-90, or other angles. The difference between AB is related to the scanning angle and the orbital height of the low-orbit satellite, and the present invention does not specifically limit it.

[0087] Comparative Example

[0088] Using a conventional active phased array antenna array, a total of 1024 phased array antenna units are arranged in a square array with 32 units in each dimension. The array factor gain of this array is 30dB, the unit gain at 0° is 3dB, and the radiation capability at 60° is -2dB. Taking the satellite orbit of the GW-2 constellation as an example, the radius of the earth is 6371 kilometers, and it is assumed that the operating frequency of the satellite and the terminal is around 20GHz. The orbit altitude of constellation 1 is 550km. For conventional satellite phased array antennas, when the satellite is at 0°, the space loss between the satellite and the terminal is 173dB. At this time, the total loss through space and the phased array antenna = -173dB + 33dB = -140dB. When the satellite is at 60°, the total loss through space and the phased array antenna = -178.2dB + 28dB = -150.2dB, such as Fig.12 As shown by the sixth solid line in , the scanning loss varies greatly, with a maximum change of 10.2dB. The bottleneck of the overall communication system is the worst link loss of -150.2dB. The orbit altitude of constellation 2 is 1145km. For conventional satellite phased array antennas, when the satellite is at 0°, the space loss between the satellite and the terminal is 179.6dB. At this time, the total loss through space and the phased array antenna = -179.6dB + 33dB = -146.6dB. When the satellite is at 60°, the total loss through space and the phased array antenna = -184dB + 28dB = -156dB, as shown in Fig.13 As shown by the seventh solid line in the figure, the scanning loss varies greatly, with a maximum change of 9.4dB. The bottleneck of the overall communication system is the worst link loss of -156dB. Whether the terminal is connected to constellation 1 or constellation 2, the loss is extremely large when scanning at a large angle. The performance of the overall communication link is greatly affected by the change of the scanning angle. In addition, the loss of the worst bottleneck point of constellation 1 is -150.2dB, and the loss of the worst bottleneck point of constellation 2 is -156dB. For some enterprise services that are sensitive to rate, bit error rate and reliability, if affected by harsh environments, disconnection may occur even near the bottleneck point at a large angle, greatly affecting the user experience.

[0089] Example 1

[0090] The switchable active phased array antenna designed according to the present invention has an operating frequency of about 20 GHz. The antenna units are combined into an array antenna of 1024 units, arranged in a square array, with 32 units in each dimension. Fig. 9 As shown, the array arrangement of the present invention can be varied and is not limited to a specific form. For the convenience of description, a square array is selected. Then the array factor gain of this array is 30dB. When the terminal is connected to the track 550KM, Fig.10As shown in Figure 2, when the designed array antenna scans to 60°, the overall gain of the array is 32dB, and when the array antenna scans to 0°, the overall gain of the array is 26.8dB. When the terminal is connected to the track at 1145KM, Fig.11 As shown, when the designed array antenna scans to 60°, the overall gain of the array is 31.6 dB, and when the array antenna scans to 0°, the overall gain of the array is 27.2 dB.

[0091] The innovative phased array antenna designed by the present invention establishes a communication connection with a low-orbit satellite during operation. Taking the satellite orbit of the GW-2 constellation as an example, when the terminal is connected to the orbit at 550 km, Fig.14 As shown, when the satellite is at 0°, according to the classic transmission formula, the space loss between the satellite and the terminal is 173dB. At this time, the total loss through space and the phased array antenna = -173dB + 26.8dB = -146.2dB. When the satellite is at 60°, the total loss through space and the phased array antenna = -178.2dB + 32dB = -146.2dB. In the same orbit, when scanning at different angles, the two have the same link and communication performance. The conventional antenna array has a minimum of -150.2dB within the scanning range, while the innovative array antenna is -146.2dB, which is 4dB higher than the conventional one. That is, the conventional antenna array has a radiation capacity of only about 40% of the innovative phased array when scanning to the lowest point of 60°. Therefore, the innovative phased array antenna has a significant improvement over the conventional array antenna. After the switch is switched, when the terminal is connected to the orbit of 1145KM, as shown Fig.15 As shown in the figure, when the satellite is at 0°, according to the classic transmission formula, the space loss between the satellite and the terminal is 179.6dB. At this time, the total loss through space and phased array antenna = -179.6dB + 27.2dB = -152.4dB. When the satellite is at 60°, the total loss through space and phased array antenna = -184dB + 31.6dB = -152.4dB. In the same orbit, when scanning at different angles, the links of the two are the same, and the communication performance is also the same. The conventional antenna array of this orbit has a minimum of -156dB within the scanning range, while the innovative array antenna is -152.4dB, which is 3.6dB higher than the conventional one. That is, the radiation capacity of the conventional antenna array at the lowest point of 60° is only about 43.7% of that of the innovative phased array. Therefore, the innovative phased array antenna has a significant improvement over the conventional array antenna.

[0092] It can be seen that through the switching operation of the innovative phased array antenna, the performance of the overall communication link of satellites in the same orbit is not affected by the change of the scanning angle, there are normal slight differences in the communication link loss in different orbits, and different orbital heights will not be switched arbitrarily during normal satellite communication. The phased array antenna of the present invention can greatly improve the user experience, and for some corporate businesses that are sensitive to rate, bit error rate and reliability, they will not be affected by harsh environments, greatly improving the reliability and stability of the satellite communication system.

[0093] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A switchable phased array antenna for a low-orbit satellite communication terminal, comprising a plurality of antenna radiators, characterized in that: The unit radiation pattern of the switchable phased array antenna presents the same curve in the longitudinal section at any position, and the shape of the curve is represented as follows: the radiation energy of the antenna is small at 0°, and the radiation energy of the antenna is maximum at the angles of X° and -X°; The unit pattern graphics satisfy the requirement of low radiation energy at the zenith and high radiation energy at large angles; The element directivity pattern is changed by switching the antenna elements.

2. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 1, characterized in that: On any longitudinal section of the unit pattern, from 0° to X°, the radiation energy of the unit pattern increases as the angle approaches X°; When the angle exceeds X°, the radiation energy of the unit pattern decreases as the angle moves away from X°.

3. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 1 or 2, characterized in that: On any longitudinal section of the unit pattern, from 0° to -X°, the radiation energy of the unit pattern increases as the angle approaches -X°; When the angle exceeds -X°, the radiation energy of the unit pattern decreases as the angle moves away from -X°.

4. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 1, characterized in that: Also includes: A feed network for distributing signals to the various antenna radiators; A receiving module for converting received electromagnetic waves into electrical signals; Transmitter module used to convert electrical signals into electromagnetic waves.

5. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 4, characterized in that: The switchable phased array antenna is provided with a switch for the antenna radiator to radiate the electromagnetic field.

6. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 5, characterized in that: The switch is arranged inside the antenna radiator and is used to change the radiation electromagnetic field of the antenna radiator.

7. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 5, characterized in that: The switching switch is arranged at the feeding network and is used to change the feeding amplitude or phase size of different feeding ports.

8. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 1, characterized in that: The array pattern of the switchable phased array antenna = unit pattern * array factor.

9. The switchable phased array antenna for low-orbit satellite communication terminal according to claim 1, characterized in that: The value range of X is: 0≤X≤90.

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