Switchable phased array antenna for low earth orbit satellite communication terminals

Abstract

The application relates to a switchable phased array antenna applied to a low-orbit satellite communication terminal, comprising a plurality of antenna radiators, and the longitudinal section of the unit pattern of the switchable phased array antenna at any position is a same curve, the curve shape is represented as: the radiation energy of the antenna is small at 0 DEG, the radiation energy of the antenna is maximum at X DEG and -X DEG angles; the unit pattern satisfies the pattern of low radiation energy at the zenith and high radiation energy at a large angle; the unit pattern is changed through switching of the antenna unit. The antenna pattern of the application satisfies the pattern of low gain at the zenith and high gain when scanning to a large angle, only the phased array antenna and the antenna unit of the terminal are changed, other hardware is not changed, on the basis of improving the performance of the phased array antenna, the existing mature technology and modules can be used to the maximum extent, the complexity of batch production can be reduced, and good engineering practicability is achieved.

Description

TECHNICAL FIELD

[0001] The application 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

[0002] In recent years, with the development of satellite communication technology, the continuous reduction of commercial space costs, and the development of new communication systems such as 5G+ and 6G, low-orbit satellite communication networks with global coverage advantages have begun to flourish, and low-orbit satellite communication industries have gradually become one of the new engines of future communication industries, and will be an important part of future 6G networks.

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

[0004] At the same time, a large-scale low-orbit satellite communication constellation is generally composed of multiple satellite sub-constellations with different orbital heights. For example, in September 2020, China Star Network submitted a spectrum allocation file to the International Telecommunication Union (ITU). The file exposed two wideband constellation plans named GW-A59 and GW-2, which plan to launch a total of 12992 satellites. The "GW" constellation includes two sub-constellations, and the orbital heights are also divided into two groups. The satellites of the GW-A59 sub-constellation are distributed in extremely low orbits at about 550 km, and the satellites of the GW-2 sub-constellation are distributed in near-earth orbits at 1145 km. The orbital inclination of the two groups of satellites is distributed between 30°-85°.

[0005] An antenna is a device for transmitting and receiving electromagnetic energy, and a phased array antenna used for satellite communication generally needs to combine multiple antennas to form an array antenna to realize functions such as beam scanning. For example, StarLinkDish, the entire phased array has more than 1300 antenna units, which form a phased array antenna to transmit and receive satellite signals. The main factors for controlling the array antenna pattern are four: unit 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 related to the array factor.

[0006] The performance of the phased array antenna currently used regularly meets the following rules: when the phased array scans to 0°, the gain of the antenna is the highest; when the phased array scans to 60°, the gain of the antenna is the lowest, and according to engineering experience, the gain is about 5 dB 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 the low-orbit satellite is low, and the moving speed of the satellite is very fast. For the terminal, the time of connecting with a satellite each time is only ten minutes, and in the ten minutes, the beam of the terminal needs to be scanned from 60° to -60°. The space loss of the same orbit also changes by several dB. At the same time, the gain capacity of the terminal antenna relative to the strongest point also changes by about 5 dB. Assuming that the signal strength of the satellite transmission and reception remains unchanged, when the terminal beam is scanned from 60° to -60°, the overall link loss relative to the strongest point of the signal also changes by nearly 10 dB. This is a very large fluctuation. Although a margin is left for the overall link design to cope with the change of the channel loss, the terminal rate of user communication will also change in a short time. In some loss-increased scenarios, such as a rainy scenario, the signal loss is further increased when passing through the humid air, and the space loss of scanning to a large angle is also larger. The two are superimposed, which greatly affects the user experience. Even for some enterprise businesses sensitive to rate, bit error rate and reliability, scanning to a large angle may even cause disconnection, which has a bad influence on the user. SUMMARY

[0008] To solve the technical problems existing in the prior art, the purpose of the present application is to provide a switchable phased array antenna applied to a low-orbit satellite communication terminal. Only the phased array antenna and its antenna unit of the terminal are changed, and other hardware is not changed. On the basis of improving the performance of the phased array antenna, the existing mature technology and modules can be used to the maximum extent, the complexity of batch production can be reduced, and good engineering practicability is achieved.

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

[0010] The unit pattern meets the graph that the radiation energy at the zenith is low and the radiation energy at a large angle is high.

[0011] The unit pattern is changed through switching of the antenna unit.

[0012] According to one of the technical solutions of the present application, on any longitudinal section of the unit directional diagram, when 0° to X°, the radiation energy of the unit directional diagram is larger as the angle is closer to X°;

[0013] When more than X°, the radiation energy of the unit directional diagram is smaller as the angle is farther away from X°.

[0014] According to one of the technical solutions of the present application, on any longitudinal section of the unit directional diagram, when 0° to -X°, the radiation energy of the unit directional diagram is larger as the angle is closer to -X°;

[0015] When more than -X°, the radiation energy of the unit directional diagram is smaller as the angle is farther away from -X°.

[0016] According to one of the technical solutions of the present application, further comprising:

[0017] A feed network for distributing signals to each antenna radiator;

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

[0019] A transmitting module for converting electrical signals into electromagnetic waves.

[0020] According to one of the technical solutions of the present application, the switchable phased array antenna is configured with a switching switch for the radiated electromagnetic field of the antenna radiator.

[0021] According to one of the technical solutions of the present application, the switching switch is arranged inside the antenna radiator, for changing the radiated electromagnetic field of the antenna radiator.

[0022] According to one of the technical solutions of the present application, the switching switch is arranged at the feed network, for changing the feed amplitude or phase size of different feed ports.

[0023] According to one of the technical solutions of the present application, the array directional diagram of the switchable phased array antenna = unit directional diagram * array factor.

[0024] According to one of the technical solutions of the present application, the value range of X is 0≤X≤90.

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

[0026] The application, different from the conventional satellite communication phased array antenna, innovatively designs the array antenna pattern to meet the low-orbit scene requirement of the low-orbit satellite communication, and the innovatively designed antenna pattern meets the pattern of low gain at the zenith and high gain when scanning to a large angle, only the phased array antenna and the antenna unit of the terminal are changed, other hardware is not changed, on the basis of improving the performance of the phased array antenna, the existing mature technology and module can be used to the maximum extent, the complexity of batch production can be reduced, and good engineering practicability is obtained.

[0027] When the phased array is scanned, 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 application can compensate 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 the conventional phased array antenna, which is beneficial to improving the performance of the communication system.

[0028] The application, the pattern of the antenna can be switched by a switch to meet different orbit altitudes of a large-scale constellation. For different orbit altitudes, the same angle can be realized by switching the pattern to achieve different radiation energy intensity, so as to adapt to satellites of different orbit altitudes. When the phased array antenna is composed, the pattern of the array antenna is low at the zenith and high when scanning to a large angle, the same angle can be realized by switching to achieve different sizes of gain to meet different orbit altitudes of satellites, and the pattern can ensure that the communication link loss of the same orbit altitude is roughly equivalent, which is beneficial to the consistency and stability of the communication system. Such a phased array antenna is suitable for large-scale low-orbit satellite communication constellations, and has a large constellation with multiple different orbit altitudes. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The figure shows the main lobe of the array antenna pattern scanned to different angles according to the conventional array antenna principle;

[0031] Figure 2 The figure shows the pattern of a conventional unit antenna according to the conventional array antenna principle;

[0032] Figure 3 The figure shows the gain and the main lobe of the pattern of the conventional array antenna scanned to different angles;

[0033] Fig. 4(a) and Fig. 4(b) show the process of the phased array antenna changing the main lobe beam pointing to the satellite and establishing communication with the satellite according to the satellite moving to a certain angle, wherein the communication link distances at different angles such as 0°, 60° and -60° are shown;

[0034] Figure 5 Fig. 5 shows a schematic diagram of the element pattern of a switchable phased array antenna according to an embodiment of the present application;

[0035] Fig. 6(a) and Fig. 6(b) show a schematic diagram of the switching mode of the element pattern of a phased array antenna according to the present application;

[0036] Figure 7 Fig. 7 shows a schematic diagram of the gain and the main lobe of the pattern of a phased array antenna scanning to different angles according to an embodiment of the present application;

[0037] Figure 8 Fig. 8 shows a switchable pattern according to an embodiment of the present application, wherein the curves of the pattern are different equations to meet different application scenarios;

[0038] Figure 9 Fig. 9 shows an array antenna arrangement according to an embodiment of the present application;

[0039] Figure 10 Fig. 10 shows a square array antenna pattern scanning to different angles according to an embodiment of the present application;

[0040] Figure 11 Fig. 11 shows a square array antenna pattern scanning to different angles according to another embodiment of the present application;

[0041] Figure 12 Fig. 12 shows a schematic diagram of the overall link calculation of a phased array antenna scanning to different angles according to an embodiment of the present application, including antenna gain and spatial loss, wherein the satellite orbit is 550 KM;

[0042] Figure 13 Fig. 13 shows a schematic diagram of the overall link calculation of a phased array antenna scanning to different angles according to an embodiment of the present application, including antenna gain and spatial loss, wherein the satellite orbit is 1145 KM;

[0043] Figure 14 Fig. 14 shows the signal energy of the satellite radiation signal received by the antenna and reaching the receiver according to an embodiment of the present application, wherein the satellite orbit is 550 KM;

[0044] Figure 15This indicates the signal energy of the satellite radiated by the satellite reaching the receiver after being received by the antenna when the satellite orbit is 1145 km according to one embodiment of the present invention. Detailed Implementation

[0045] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0046] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the 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, electromagnetic waves propagate to the array surface in the form of plane waves (the wavefront is the equiphase surface). The element spacing of the linear array is d, the number of elements is n, and the beam pointing angle is θ. According to the superposition principle, the radiation pattern of the array factor is as follows:

[0048]

[0049] Among them, A n d represents the magnitude weighting of the nth unit. n It is the distance from the nth cell to the reference point, k is the wave number, λ is the wavelength, and:

[0050]

[0051] Beam scanning of the array antenna can be achieved by changing the beam index angle θ. Figure 1 The main lobe radiation patterns at different scanning angles are shown. The radiation pattern of a conventional antenna element is shown below. Figure 2 As shown: the gain is greatest at the zenith, and decreases at a certain angle away from the zenith. The greater the angle of deviation, the greater the decrease in gain at a certain angle.

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

[0053] The radius of the earth is 6371 km, the orbit height of low orbit satellite communication is 500-2000 km, the satellite phased array terminal on the earth has scanning capability, generally it has scanning +60° to scanning -60° capability. Therefore, when the satellite appears in the terminal view 60° position, it can start communication, at the same time, the satellite moves around the earth, moves to the satellite in the terminal view -60° position, during this period, the terminal establishes stable and reliable communication connection with the satellite, until the satellite exceeds the terminal view -60° position, the terminal controls its own beam, switches to the next satellite, the next satellite is just at the position of the terminal view 60° position, continues the communication service, according to this rule, the satellite provides stable and reliable communication service for the ground terminal through the relay mode. 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 produces loss, the loss is inconsistent at different distances, the longer the distance, the greater the loss, assuming that the satellite transmission and reception performance is fixed, therefore, at different angles, the signal strength reaching the terminal is inconsistent, which 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, 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, the faster the communication rate, the fastest point is the position of 0° angle.

[0054] Taking the satellite orbit of GW-2 constellation as an example, as shown in FIG. 4, the orbit height is 550 km and 1145 km two near-earth orbits, the radius of the earth is 6371 km. When the satellite is at 0°, the distance between the satellite and the terminal is 550 km and 1145 km, when the satellite is at 60°, the corresponding distance between the satellite and the terminal is about 970 km and 1900 km, so when the satellite scans from 0° to 60° relative to the terminal, the distance between the satellite and the terminal increases from 550 km to 970 km, or from 1145 km to 1900 km.

[0055] Assuming that the working frequency of the satellite and the terminal is near 20 GHz, according to the classical transmission formula, when the distance between the satellite and the terminal is 550 km, the space loss is 173 dB, when the distance is 970 km, the space loss is 178.2 dB, the difference between the two is 5.2 dB. When the distance is 1145 km, the space loss is 179.6 dB, when the distance is 1900 km, the space loss is 184 dB, the difference between the two is 4.4 dB. When the satellite scans from 0° to 60° relative to the terminal, the space loss changes from 173 dB to 178.2 dB at 550 km orbit, and the space loss changes from 179.6 dB to 184 dB at 1145 km 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 how much the satellite on the same orbit is opposite to the angle of the terminal, the signal received by the terminal from the satellite should be equal in strength, which facilitates the subsequent modulation and demodulation of the terminal to the signal, so that the ideal signal can keep the speed of the terminal unchanged, which can greatly improve the user experience and will not cause the user to be disturbed by the high and low speed.

[0058] As shown in the Figures 5 to 13 The application provides a switchable phased array antenna applied to a low-orbit satellite communication terminal, which comprises a plurality of antenna radiators (one antenna radiator can be regarded as corresponding to one antenna unit), a unit pattern of the switchable phased array antenna is a same curve in a longitudinal section at any position, and the curve shape is represented as: the radiation energy of the antenna is small at 0°, and the radiation energy of the antenna is maximum at X° and-X° angles.

[0059] The unit pattern meets the requirement that the radiation energy is low at the zenith and the radiation energy is high at a large angle.

[0060] The unit pattern is changed through switching of the antenna units.

[0061] As shown in the Figure 5 The unit pattern of the array antenna is innovatively designed to meet the low-orbit scenario requirement of low-orbit satellite communication, and the innovatively designed antenna unit pattern meets the requirement that the gain is low at the zenith and the gain is high when scanning to a large angle. Meanwhile, the unit pattern of the antenna can be switched through a switch to meet different orbit height sub-constellations of a large-scale constellation.

[0062] Figure 5 The unit pattern in any position is a longitudinal section, and the complete pattern of the unit pattern of the switchable phased array antenna can be regarded as: the pattern in the above formula is rotated by 360° with the center line of 0° as an axis. Figure 5

[0063] The unit pattern of the antenna meets the requirement that the radiation energy is low at the zenith and the radiation energy is high at a large angle. When the phased array is scanned, 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 application 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] ​Further, the application has switching function, the unit pattern is changed by switching of the antenna unit, for different orbit height, the same angle of radiation energy intensity can be realized by switching of the pattern, to adapt to the satellite of different orbit height. When the phased array antenna is composed, the gain of the array antenna zenith is low, the gain of the pattern is high when scanning to large angle, the same angle of different gain can be realized by switching to meet the orbit height of different satellite, at the same time, the pattern can ensure that the communication link loss of the same orbit height is roughly equivalent, which is beneficial to the consistency and stability of the communication system. At the same time, the phased array antenna of the application is suitable for large-scale low-orbit satellite communication constellation, and has a variety of different orbit height of huge constellation.

[0065] In some embodiments of the application, in any longitudinal section of the unit pattern, when 0° to X°, the radiation energy of the unit pattern is larger as the angle is closer to X°;

[0066] When more than X°, the radiation energy of the unit pattern is smaller as the angle is farther away from X°;

[0067] When 0° to-X°, the radiation energy of the unit pattern is larger as the angle is closer to-X°;

[0068] When more than-X°, the radiation energy of the unit pattern is smaller as the angle is farther away from-X°.

[0069] As shown in Figure 5 and Figure 8 , the array antenna needs to scan to 60°, that is, X=60, when the terminal is connected to the orbit 550KM, as shown in the first curve in Figure 5 , the radiation energy of the antenna pattern is the largest at the angle of 60° and-60°, the corresponding gain is 2dB, the corresponding gain of the antenna pattern at 0° is-3.2dB, when the terminal is connected to the orbit 1145KM, as shown in the second curve in Figure 5 , the radiation energy of the antenna pattern is the largest at the angle of 60° and-60°, the corresponding gain is 1.6dB, the corresponding gain of the antenna pattern at 0° is-2.8dB, the two patterns are switched by the switch, and the rules are similar, when 0° to 60°, the radiation energy of the pattern is larger as the angle is closer to 60°, when more than 60°, the radiation energy of the pattern is smaller as the angle is farther away from 60°, when 0° to-60°, the radiation energy of the pattern is larger as the angle is closer to-60°, when more than-60°, the radiation energy of the pattern is smaller as the angle is farther away from-60°. The 3D graph of the antenna is rotationally symmetrical around the center line of 0°, the vertical line passing through 0° is taken as a section of the 3D graph, the 2D graph of each section is similar, and all satisfy the variation rule of the radiation energy of the pattern.

[0070] For the curve equation of the variation law, the radiation energy meeting the directional diagram is larger as the angle is closer to-60° and 60°. For specific equation, the application does not make any stipulation.

[0071] As shown in FIG. 1, three possible equation forms are listed, which can be a straight line as shown by the third line segment in FIG. 1, or a curve equation as shown by the fourth curve in FIG. 1, or two curve equations spliced as shown by the fifth curve in FIG. 1. The curve equation of the application includes the case as shown in FIG. 1, but is not limited to the case as shown in FIG. 1; the curve equation can also be switched by a switch, and can be flexibly and adaptively adjusted according to different scenes to improve the communication quality of the terminal as a whole. Figure 8 Figure 8 Figure 8 Figure 8 Figure 8 Figure 8

[0072] In some embodiments of the application, the switchable phased array antenna of the application further comprises:

[0073] a feed network for distributing signals to each antenna radiator;

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

[0075] a transmitting module for converting electrical signals into electromagnetic waves.

[0076] In some embodiments of the application, the switchable phased array antenna is configured with a switching switch for the radiated electromagnetic field of the antenna radiator.

[0077] In some embodiments of the application, the switching switch is arranged between two adjacent antenna radiators, and is used to change the radiated electromagnetic field of the antenna radiators.

[0078] In some embodiments of the application, the switching switch is arranged at the feed network, and is used to change the feed amplitude or phase size of different feed ports.

[0079] By arranging a switching switch at the antenna radiator or the feed network of the antenna, the switching switch can be placed inside the antenna body to realize the function that the directional diagram of the unit antenna can be switched.

[0080] FIG. 6(a) shows a schematic diagram of switching the antenna radiators, and FIG. 6(b) is a schematic diagram of switching the feed ports of the antenna.

[0081] ​​​​​​As shown in Figure 6(a), a switching switch is installed between antenna radiators 1 and 2, and between antenna radiators 3 and 4. The switching switches are part of the antenna; their states alter the radiated electromagnetic field of the antenna radiators, thereby changing the antenna's radiation pattern and achieving the antenna pattern switching function. Antenna radiators 1 and 3 are connected via a feed network.

[0082] The switch can also be placed at the antenna feed point, 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). Switching between different feed ports changes the feed amplitude or phase of different feed ports, thereby changing the radiated electromagnetic field of the antenna radiator and thus changing the antenna radiation pattern, achieving the antenna pattern switching function. This invention does not specify the number of antenna feed ports, the number of switches, or the number of switching states.

[0083] In some embodiments of the present invention, the array pattern of the switchable phased array antenna is equal to the element pattern multiplied by the array factor.

[0084] The array pattern of the active phased array antenna of the present invention is equal to the element pattern multiplied by the array factor Q.

[0085] Array factors are adopted as follows Figure 1 In the conventional design shown, the array antenna scans a certain cross-section, taking the same cross-section of the 3D radiation pattern. The array antenna of the present invention scans radiation patterns at different angles, as shown below. Figure 7 As shown, the phased array gain is maximum at X° and -X°, which is A*Q (where Q is equivalent to the radiation intensity of the array factor, and A is the radiation intensity of the element, which can be changed by switching, such as A1, A2, A2, etc.). The phased array gain is B*Q at 0° (which can be B1, B2, B2, etc. by switching). From 0° to X°, the gain of the phased array gain increases as the angle approaches X°. Beyond X°, the gain decreases as the angle moves away from X°. From 0° to -X°, the gain of the phased array gain increases as the angle approaches -X°. Beyond -X°, the gain decreases as the angle moves away from -X°.

[0086] Furthermore, angle X is related to the design scanning angle of the terminal product, and its value range can be set to 0-90 degrees, or other angles. The difference between A and B is related to the scanning angle and the orbital altitude of the low-Earth orbit satellite, and this invention does not impose specific limitations on it.

[0087] Comparative Example

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

[0089] Example 1

[0090] The switchable active phased array antenna designed according to this invention operates at a frequency around 20 GHz. These antenna elements are arranged into a 1024-element array antenna, with 32 elements in each dimension arranged in a square array. Figure 9 As shown, the array arrangement of this invention can be varied and is not limited to a specific form. For ease of description, a square array is chosen. Therefore, the array factor gain of this array is 30dB. When the terminal is connected to the 550km track, as... Figure 10As shown, for the designed array antenna scanning 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 orbit 1145KM, as shown Figure 11 As shown, for the designed array antenna scanning to 60°, the overall gain of the array is 31.6dB, and when the array antenna scans to 0°, the overall gain of the array is 27.2dB.

[0091] The innovative phased array antenna designed in the application is in communication connection with a low earth orbit satellite in the working process. Taking the satellite orbit of the GW-2 constellation as an example, when the terminal is connected to the orbit 550KM, as shown Figure 14 As shown, when the satellite is at 0°, according to the classical transmission formula, the space loss between the satellite and the terminal is 173dB, and at this time, the total loss through the space and the phased array antenna is -173dB+26.8dB=-146.2dB. When the satellite is at 60°, the total loss through the space and the phased array antenna is -178.2dB+32dB=-146.2dB. The links of the two are the same, and the communication performance is also the same when scanning to different angles in the same orbit. The lowest of the conventional antenna array in the scanning range is -150.2dB, while the innovative array antenna is -146.2dB, which is 4dB higher than the conventional one. That is, the radiation ability of the conventional one scanning to the lowest point of 60° is only about 40% of the innovative phased array. Therefore, the innovative phased array antenna has a significant improvement compared with the conventional array antenna. After switching, when the terminal is connected to the orbit 1145KM, as shown Figure 15 As shown, when the satellite is at 0°, according to the classical transmission formula, the space loss between the satellite and the terminal is 179.6dB, and at this time, the total loss through the space and the phased array antenna is -179.6dB+27.2dB=-152.4dB. When the satellite is at 60°, the total loss through the space and the phased array antenna is -184dB+31.6dB=-152.4dB. The links of the two are the same, and the communication performance is also the same when scanning to different angles in the same orbit. The lowest of the conventional antenna array in the scanning range is -156dB, while the innovative array antenna is -152.4dB, which is 3.6dB higher than the conventional one. That is, the radiation ability of the conventional one scanning to the lowest point of 60° is only about 43.7% of the innovative phased array. Therefore, the innovative phased array antenna has a significant improvement compared with the conventional array antenna.

[0092] Therefore, through the switching operation of the innovative phased array antenna, the performance of the overall communication link of the satellites belonging to the same orbit is not affected by the change of the scanning angle, there is a normal small difference in the communication link loss of different orbits, and different orbit heights will not be randomly switched in the normal satellite communication process. The phased array antenna of the application can greatly improve the user experience, and for some enterprise businesses sensitive to rate, bit error rate and reliability, it will not be affected by the harsh environment, greatly improving the reliability and stability of the satellite communication system.

[0093] The basic principles, main features and advantages of the application are shown and described above. Those skilled in the art should understand that the application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the application and are not intended to limit the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection of the application is defined by the appended claims and their equivalents.

Claims

1. A switchable phased array antenna applied to a low-orbit satellite communication terminal, comprising a plurality of antenna radiators, characterized in that, a longitudinal section of the unit pattern of the switchable phased array antenna at any position is a same curve, and the curve shape is that the antenna has a smaller radiation energy at 0° and a maximum radiation energy at X° and -X° angles; the unit pattern meets the pattern of a low radiation energy at the zenith and a high radiation energy at a large angle; the switchable phased array antenna is configured with a switching switch for the radiation electromagnetic field of the antenna radiators, and the unit pattern is changed by the switching switch; the switchable antenna units constitute a phased array antenna, the pattern of the phased array antenna is changed by switching of the antenna units, and link loss balance of low-orbit satellite communication is realized: the total loss of different scanning angles under the same orbit is made equivalent, and after switching to another orbit satellite, the unit pattern is changed, the pattern of the array antenna is changed, and the total loss of different scanning angles under another orbit is made equivalent.

2. The switchable phased array antenna for a low earth orbit satellite communication terminal of claim 1, wherein, on any longitudinal section of the unit pattern, from 0° to X°, the radiation energy of the unit pattern is larger as the angle is closer to X°; beyond X°, the radiation energy of the unit pattern is smaller as the angle is farther away from X°.

3. The switchable phased array antenna for a low earth orbit satellite communication terminal of claim 1, wherein, on any longitudinal section of the unit pattern, from 0° to -X°, the radiation energy of the unit pattern is larger as the angle is closer to -X°; beyond -X°, the radiation energy of the unit pattern is smaller as the angle is farther away from -X°.

4. The switchable phased array antenna for a low earth orbit satellite communication terminal of claim 1, wherein, the switching switch is arranged inside the antenna radiator, and is used to change the radiation electromagnetic field of the antenna radiator.

5. The switchable phased array antenna for a low earth orbit satellite communication terminal of claim 1, wherein, the switching switch is arranged at a feeding network, and is used to change the feeding amplitude or phase size of different feeding ports.

6. The switchable phased array antenna for a low earth orbit satellite communication terminal of claim 1, wherein, X is in the range of 0≤X≤90.

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