Compact dual-frequency dual-circularly-polarized satellite-borne common-aperture antenna array

Abstract

The invention discloses a compact dual-frequency dual-circularly-polarized satellite-borne common-caliber antenna array, which belongs to the technical field of antennae, and comprises a plurality of basic sub-arrays, each basic sub-array comprises a low-frequency receiving antenna, a high-frequency transmitting antenna, a metal cavity, a transmitting-receiving antenna differential feed phase-shift network and an antenna supporting structure which are sequentially connected from top to bottom; the transmitting antenna is fixed on the metal cavity, the metal cavity is connected with a feed probe insulator, a metal probe in the middle of the feed probe insulator is connected with feed coupling branches of the receiving antenna and the transmitting antenna in a spot welding mode, the metal cavity is provided with an open slot, and the open slot is communicated with the feed probe insulator. The receiving antenna is inserted into the transmitting antenna and the open slot in a plug-in manner; wherein the receiving antenna and the transmitting antenna both adopt an antenna form of differential feed and inverted-L-shaped probe adjacent coupling feed. According to the array, through reasonable arrangement of the receiving antenna, the transmitting antenna, the metal cavity, the transmitting and receiving antenna differential feed phase shift network and the antenna supporting structure, the requirements of low cost, integration, light weight and multi-band application of the satellite-borne phased array are met.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array. Background Art

[0002] At present, satellite communication technology has gradually moved from traditional satellite navigation, emergency communication, weather monitoring, military applications and other special applications to the commercial civilian market, such as personal terminal data communication, mobile phone direct connection to satellite and other technical fields. Therefore, there is an urgent need for low-cost, integrated, lightweight, multi-band application of satellite-borne phased arrays.

[0003] Satellite communications generally use the FDD system. The frequencies within the working bandwidth are divided into pairs of frequency bands with similar frequencies, and the transmit and receive channels use the same set of antenna arrays. However, today, since the L / S / C bands have been occupied by ground networks, global navigation satellite systems, etc., it is difficult to find sufficiently wide and adjacent spectrum pairs. When it comes to broadband applications, it is necessary to consider expanding the uplink and downlink spectrum intervals; and the cost of a large frequency difference is that two sets of antennas must be installed for receiving and transmitting respectively, which increases the size and cost of the antenna. Compared with separate transmit and receive antennas, under the condition of the same aperture, the common aperture antenna can obtain a larger antenna array aperture and improve space utilization. Secondly, the cost of satellite launch is affected by weight. When the satellite payload is limited, the use of common aperture antenna technology is the best way to achieve lightweight, integrated and low-cost phased arrays because it can realize the sharing of the RF front end for transmit and receive.

[0004] The existing common aperture antenna technology has the following defects and shortcomings:

[0005] 1) When the common-aperture antenna is working, there is the challenge of multi-antenna coupling interference, which is mainly divided into co-frequency coupling and heterodyne coupling. Co-frequency coupling is the coupling between antenna units in the same working frequency band, and heterodyne coupling is the coupling between high-frequency and low-frequency antenna units. When the phased array antenna is working, the array element spacing is generally half a wavelength, and the high and low frequency antennas of the co-aperture antenna array generally adopt a nested design, resulting in a strong coupling caused by the small spacing between adjacent heterodyne antenna units. This strong heterodyne coupling will not only cause distortion of the array pattern, but also lead to the overall impedance mismatch and isolation deterioration of the antenna array system. Especially during the phased array scanning process, the input impedance of the antenna will change with the change of the scanning angle. This impedance mismatch and pattern distortion caused by the mutual coupling of the antenna greatly limit the scanning range of the antenna;

[0006] 2) For co-aperture antennas, since the transmitter and receiver share the same RF front end, the transmit link will interfere with the receive link. This interference is mainly reflected in two aspects: a. The transmit link power is generally high. When the transmit signal enters the receive link, it will cause the receive link to be saturated or even damaged; b. The noise of the transmit link in the receive frequency band will enter the receiver, interfere with the receive signal, and affect the receiver's receiving performance;

[0007] 3) Due to the interference of co-frequency coupling and heterodyne coupling, circularly polarized common-aperture antennas generally have the problem of large-angle scanning degradation and axial ratio deterioration as the scanning angle increases;

[0008] 4) Challenges in the layout of co-aperture antenna technology. Generally, the high and low frequency bands of co-aperture antennas need to meet integer frequency ratios, and the spacing between low-frequency antenna unit elements and high-frequency antenna unit elements follows an integer multiple relationship to form an interlaced nested layout. When the high and low frequency ratios do not meet integer frequency ratios, array layout is difficult. Secondly, in order to reduce heterodyne coupling, the spacing between high and low frequency antenna arrays generally cannot meet periodic layouts, resulting in the spacing between the transceiver units of the co-aperture antenna not meeting the condition of d<λ / (1+sinθ) at certain frequencies, causing the array pattern to produce grating lobes;

[0009] 5) Since the transmitting and receiving antennas of the same aperture are placed at different heights, the low-frequency antenna will block the high-frequency antenna. Summary of the invention

[0010] The purpose of the present invention is to overcome the technical problems existing in the prior art and to provide a compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array.

[0011] The objective of the present invention is achieved through the following technical solutions:

[0012] A compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array is provided, comprising a plurality of basic sub-arrays, wherein the basic sub-arrays include a low-frequency receiving antenna, a high-frequency transmitting antenna, a metal cavity, a transmitting and receiving antenna differential feeding phase shifting network and an antenna support structure connected in sequence from top to bottom. The receiving antenna and the transmitting antenna both adopt differential feeding + Г-type probe proximity coupling feeding.

[0013] Preferably, the transmitting antenna operates at 3.4GHz-3.7GHz, and the receiving antenna operates at 1.9GHz-2.1GHz, covering the satellite communication frequency band, and the transmit-receive frequency ratio is about 2:1. The transmitting antenna includes four high-frequency transmitting units, and the four high-frequency transmitting units include a low-frequency receiving unit, and the four high-frequency transmitting units and the low-frequency receiving unit are combined in a nested manner. Among them, the design value of the spacing between the high-frequency transmitting units in the X and Y directions is 45.5mm, and the design value of the spacing between the low-frequency receiving units in the X and Y directions is 83mm, which can meet the requirements of no grating lobe spacing within the ±51° scanning range; both the high-frequency and low-frequency antennas adopt the form of differential feeding + Г-type probe proximity coupling feeding, which enables the antenna to achieve maximum bandwidth at a relatively low profile while realizing dual circular polarization.

[0014] Preferably, in order to reduce co-frequency and cross-frequency interference, the radiation structures of the low-frequency receiving antenna and the high-frequency transmitting antenna are arranged in a staggered manner, and the radiation structure of the transmitting antenna is shielded by metal shielding holes to reduce co-frequency interference caused by surface waves. Secondly, the transmitting antenna coupling feed structure and the receiving antenna coupling structure are physically isolated by a metal cavity to increase the isolation between transmission and reception.

[0015] Preferably, the receiving antenna is a dipole antenna, and the transmitting antenna includes four microstrip patch antennas. In order to reduce the shielding of the low-frequency antenna to the high-frequency antenna and reduce cross-frequency interference, the low-frequency dipole antenna adopts the method of printing metal strips on the upper and lower layers of the substrate, and the middle is connected by through holes to act as a metal arm. The horizontal branches in the proximity coupling feeding structure of the dipole antenna and the Г-type probe are placed on the TSM-DS3 substrate in the XOZ direction and the YOZ direction. The dielectric substrate in the XOZ direction and the dielectric substrate in the YOZ direction where the dipole antenna is located are cross-slotted, and the dielectric substrates are both provided with slots with the same thickness as the substrate, and the sum of the slot depth of the dielectric substrate in the XOZ direction and the slot depth of the dielectric substrate in the YOZ direction is equal to the height of the dielectric substrate in the XOZ direction / the dielectric substrate in the YOZ direction. In order to avoid the slot design in the dielectric substrate, the middle part of the dipole antenna on the dielectric substrate in the XOZ direction is bent upward to form an arch, and the middle part of the dipole antenna on the dielectric substrate in the YOZ direction is bent downward to form an arch. This design minimizes the projection area of ​​the low-frequency receiving dipole antenna on the high-frequency transmitting antenna plane, reduces the shielding of the low-frequency antenna on the high-frequency antenna, and minimizes the design of the antenna's feeding structure and radiation structure while meeting the bandwidth requirements, and integrates the feeding and radiation structures with a single medium.

[0016] Preferably, the metal cavity is a cube, including four edge square cavities and a cross-shaped cavity in the middle, so as to improve the isolation between the receiving antenna and the transmitting antenna. The four microstrip patch antennas are fixed on the four edge cavities, and steps are provided in the four edge cavities. The steps are connected to the dielectric substrate where the horizontal branches of the G-type probe adjacent coupling feeding structure of the transmitting antenna are located, and play a supporting role for the feeding structure of the transmitting antenna. The cross-shaped edge of the metal cavity is provided with a metal slot gap, and the receiving antenna is inserted into the transmitting antenna and the slot by plugging for fixing.

[0017] Preferably, a feeding probe insulator is connected to the metal cavity, and the metal probe in the middle of the feeding probe insulator in the cross-shaped cavity is connected to the vertical branch of the G-probe proximity coupling feeding structure of the receiving antenna by spot welding; the metal probe in the middle of the feeding probe insulator in the four edge cavities is connected to the horizontal branch of the G-probe proximity coupling feeding structure of the transmitting antenna by spot welding.

[0018] Preferably, the high-frequency transmitting antenna is left-hand circular polarization, and the low-frequency receiving antenna is right-hand circular polarization.

[0019] Preferably, in order to reduce the interference between the transmitting and receiving antenna feeding networks, an electromagnetic shielding structure is added between the transmitting and receiving feeding networks, and a low-pass filter is integrated on the receiving feeding network to suppress high-frequency signals, suppress the interference of the transmitting link on the receiving link, and increase the transmitting and receiving isolation.

[0020] Preferably, the transceiver antenna differential feeding phase shift network adopts a nested layout.

[0021] Preferably, a sequential rotation arrangement is used to improve the axial ratio of the wide-angle scanning of the common aperture antenna. A 2×2 transmitting unit plus a receiving unit is used as a basic subarray. The four transmitting units are rotated 90° clockwise in sequence. Each basic subarray is composed of four arrays and then arranged as follows: Fig.10 The method shown is to rotate 90° counterclockwise in sequence to reduce the reduction in axial ratio during large-angle scanning.

[0022] It should be further explained that the technical features corresponding to the above options can be combined or replaced with each other to form a new technical solution if there is no conflict.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The high and low frequency antennas are arranged in an interlaced manner. To improve the performance of the low frequency antenna, the high frequency transmitting antenna element spacing is designed to be 45.5mm in the X and Y directions, and the low frequency receiving antenna element spacing is designed to be 83mm in the X and Y directions, which can meet the requirements of no grating lobe spacing within the ±51° scanning range. The transmitting and receiving antenna radiation structure, coupled feeding structure, transmitting and receiving antenna differential feeding phase shifting network and metal cavity are reasonably arranged to achieve a compact layout of the entire system;

[0025] 2) Due to the limited bandwidth of traditional direct-fed microstrip antennas and dipole antennas, both high- and low-frequency antenna units adopt differential feeding + Г-type probe proximity coupling feeding antenna form to achieve the requirements of gain, bandwidth and dual circular polarization;

[0026] 3) An electromagnetic shielding structure is added between the transceiver feed network to reduce the interference of the intermodulation signal of the receiving link on the transmitting link, so that the isolation of the transceiver antenna in the receiving frequency band reaches below -24dB. At the same time, a low-pass filter is integrated on the receiving feed network to suppress high-frequency signals, so that the isolation of the transceiver antenna in the transmitting frequency band reaches below -64dB, effectively suppressing the noise of the transmitting link from entering the receiver and interfering with the receiving signal;

[0027] 4) The metal cavity structure is specially designed. The cross-shaped edge of the metal cavity is provided with a metal slot for the receiving antenna to be inserted and fixed therein. The transmitting antenna substrate and the cross-shaped metal slot of the cavity together play a role in positioning and fixing the receiving antenna, so there is no need to add additional studs on the edge of the cavity to support and fix the receiving antenna, thus achieving a compact layout of high and low frequency antennas. The transceiver antenna is supported by the metal cavity. The cavity structure plays a role in feeding transition and supporting the transceiver antenna. Secondly, it can physically isolate the transceiver feed network signal and increase the transceiver isolation.

[0028] 5) A single 2×2 basic subarray transmitting antenna is arranged in a sequential rotation manner, and each basic subarray is rotated sequentially after forming an array, thereby realizing wide-angle scanning and broadband dual circular polarization of the co-aperture array antenna. When the center frequency of the receiving frequency band is scanned from 1.975 GHz to ±51°, the gain of the proposed co-aperture antenna drops by less than 3.1 dB, and because the basic subarrays rotate sequentially, the axial ratio is always less than 3 dB within the scanning range. When the center frequency of the receiving frequency band is scanned from 3.55 GHz to ±51°, the gain of the proposed co-aperture antenna drops by less than 4 dB, and because the basic subarrays rotate sequentially, the axial ratio is always less than 1 dB within the scanning range;

[0029] 6) In order to reduce the shielding of the high-frequency transmitting antenna by the low-frequency receiving antenna, the feeding structure and radiation structure of the antenna are designed to be minimized while meeting the bandwidth, and the integration of the feeding and radiation structures is realized with a single medium. The dipole antenna uses metal strips printed on the upper and lower layers of the substrate, and the metal arms are connected in the middle by through holes. The antenna and the horizontal branches in the G-type probe proximity coupling feeding structure are placed on the TSM-DS3 substrate in the XOZ and YOZ directions. The processing method is simple. Compared with the traditional dipole antenna, the advantages of this design are: a. It can be conveniently processed by PCB processing, which increases engineering practicality; b. This design minimizes the projection area of ​​the dipole antenna on the plane of the transmitting antenna to the greatest extent, reducing the shielding of the receiving antenna on the transmitting antenna; c. It reduces the strong coupling between the two antennas caused by the close distance; d. Due to the connection method of metal strips and metal columns, the current path on the dipole arm is increased, which plays a role in increasing the bandwidth;

[0030] 7) The high-frequency transmitting antenna adopts the form of feed network + TSM-DS3 medium + air medium + metal cavity, which reduces dielectric loss while facilitating installation and reducing cost and weight;

[0031] 8) The low-frequency receiving antenna adopts the form of feeding network + TSM-DS3 supporting structure + air medium + metal slot, which reduces dielectric loss while facilitating installation and reducing cost and weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the exploded diagram of the basic subarray of the common aperture antenna;

[0033] Figure 2 This is a cross-sectional view of the basic subarray;

[0034] Figure 3 This is a schematic diagram of the receiving antenna coupling feeding structure;

[0035] Figure 4 It is a schematic diagram of the connection between the receiving antenna radiation structure and the coupling feeding structure;

[0036] Figure 5 is a schematic diagram of the transmitting antenna structure;

[0037] Figure 6 This is a schematic diagram of the transmission antenna coupling feeding structure;

[0038] Figure 7 It is a schematic diagram of the metal cavity slotting structure;

[0039] Figure 8 It is a schematic diagram of the metal cavity structure;

[0040] Fig. 9It is a schematic diagram of the structure of the differential feeding phase shifting network of the lower layer transceiver antenna;

[0041] Fig.10 A schematic diagram of an array composed of basic sub-arrays;

[0042] Fig.11 This is a schematic diagram of the standing wave of the receiving antenna in the entire frequency band;

[0043] Fig.12 It is a schematic diagram of the standing wave of the transmitting antenna in the entire frequency band;

[0044] Fig.13 It is a schematic diagram of the isolation between the transmitting and receiving antennas within the receiving frequency band;

[0045] Fig.14 It is a schematic diagram of the isolation between the transmitting and receiving antennas in the transmitting frequency band;

[0046] Fig.15 Schematic diagram of the 2×4 array of basic subarrays for transmitting and receiving antenna simulation;

[0047] Fig.16 The scanning pattern of the receiving antenna basic subarray 2×4 array at the center frequency 2GHz;

[0048] Fig.17 It is a schematic diagram of the axis ratio of the receiving antenna basic sub-array 2×4 array scanning at different angles within the range of ±51° at the center frequency 2GH;

[0049] Fig.18 The scanning pattern of the basic sub-array 2×4 array of the transmitting antenna at its center frequency of 3.5 GHz;

[0050] Fig.19 This is a schematic diagram of the axis ratio of the 2×4 array of the transmitting antenna basic subarray scanning at different angles within the range of ±51° at the center frequency 3.5GH.

[0051] In the figure: 1-receiving antenna; 2-transmitting antenna; 3-middle metal cavity; 4-lower layer transceiver antenna differential feeding phase shifting network; 5-antenna fixing / supporting structure. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various configurations. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] It should be noted that the defects existing in the solutions in the above-mentioned prior art are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed in the embodiments of the present application for the above-mentioned problems below should all be the contributions made by the inventor to the present application in the process of invention and creation, and should not be understood as technical contents known to technical personnel in this field.

[0054] Based on the above related statements, since this embodiment involves mobile communication related technologies, in order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the relevant professional terms that may be involved in the present invention are explained below:

[0055] 1. FDD: It is a full-duplex communication technology used in mobile communication systems, corresponding to TDD. FDD uses two independent channels to transmit information downward and upward respectively. In order to prevent mutual interference between adjacent transmitters and receivers, there is a protection band between the two channels. FDD requires two independent channels for operation. One channel is used to transmit information from the base station to the end user, and the other channel is used to send information from the end user to the base station.

[0056] 2. TDD: Another duplex mode, the transmitter and receiver share a radio frequency, and the uplink and downlink use different time slots for communication. In TDD technology, the transmitter and receiver share a radio frequency point, and the uplink and downlink use different time slots for communication. In FDD technology, different radio frequencies are used to communicate with each other.

[0057] In view of the technical problems pointed out in the background technology, the embodiments provided by the present invention are as follows:

[0058] In an exemplary embodiment, a compact dual-frequency dual-circular polarization spaceborne co-aperture antenna array is provided, comprising a plurality of co-aperture antenna basic sub-arrays, wherein an exploded diagram of the co-aperture antenna basic sub-array is shown in FIG. Figure 1As shown, the antenna includes an upper receiving antenna 1 and a transmitting antenna 2, a coupled feeding structure of the middle transmitting and receiving antenna, an intermediate metal cavity 3, a differential feeding phase shift network 4 for the lower transmitting and receiving antenna, and an antenna fixing / supporting structure 5. Among them, the receiving antenna 1 and the transmitting antenna 2 both include a radiation structure and a coupled feeding structure, the transmitting antenna coupled feeding substrate and the radiation structure substrate are fixed on the metal cavity by screw connection, the metal cavity 3 plays the role of feeding transition, the feeding probe insulator is welded on the metal cavity 3 by welding, and the metal probe in the middle of the insulator is connected to the vertical branch of the receiving antenna Г-type probe adjacent to the coupled feeding structure and the horizontal branch of the transmitting antenna Г-type probe adjacent to the coupled feeding structure by spot welding. The low-frequency receiving antenna 1 is inserted into the transmitting antenna radiation plate and the slotted gap on the metal cavity 3 by plugging to form positioning and support. The bottom is a supporting / fixing metal plate. On the one hand, the metal plate serves to fix and support the upper radiation structure, coupling feeding structure, metal cavity, and transceiver antenna differential phase-shifting feeding network 4; on the other hand, it serves as a reference ground to facilitate the welding of the SMP connector at its bottom.

[0059] The advantage of adopting this layout is that it is easy to install. On the other hand, compared with the full PCB format, the TSM-DS3 medium + cavity + air medium format not only reduces dielectric loss, but also reduces cost and weight. The designed transmitting antenna 2 operates at 3.44GHz-3.66GHz, and the receiving antenna 1 operates at 1.92GHz-2.025GHz. The frequency ratio between the two is about 2:1. Therefore, four transmitting units and one receiving unit are combined in a nested manner. The design value of the high-frequency array element spacing in the X and Y directions is 45.5mm, and the design value of the low-frequency array element spacing in the X and Y directions is 83mm, which can meet the requirements of grating-free spacing within the ±51° scanning range. The compact layout of the entire system is achieved through the reasonable arrangement of the transmitting and receiving antenna radiation structure, the coupling feeding structure, the transmitting and receiving antenna differential feeding phase shifting network 4, and the metal cavity 3. Figure 2 As shown, since the bandwidth of the traditional directly fed microstrip antenna and the dipole antenna is limited, the receiving antenna 1 and the transmitting antenna 2 both adopt the form of G-type probe proximity coupling feeding, so that the antenna can achieve the maximum bandwidth at a relatively low profile.

[0060] Furthermore, the receiving antenna 1 is in the form of a dipole antenna. The advantage of using this antenna is that the dipole antenna has a higher gain when the frequency band is low, and the four blank quadrants formed by the cross-dipole arms are just suitable for the placement of the transmitting antenna. Figure 3The figure shows the schematic diagram of receiving antenna feeding. The receiving antenna adopts the form of coupled feeding. The four dipole arms are respectively fed by G-type probes for proximity coupling. The G-type probes are separated from the lower feeding network by insulators. The phase difference between the four ports is 90°, which achieves circular polarization and obtains the best axial ratio characteristics. Figure 4 As shown, the radiation structure and the coupled feed structure are arranged in a cross-staggered manner. The dipole antenna uses metal strips printed on the upper and lower layers of the substrate, and the middle is connected by through holes to act as a metal arm. The antenna and the coupled feed structure are placed on the TSM-DS3 substrate in the XOZ direction and the YOZ direction. The processing method is simple. Compared with the traditional dipole antenna, the advantages of this design are: a. It can be easily processed by PCB processing, which increases the engineering practicality; b. The design minimizes the projection area of ​​the dipole antenna on the transmitting antenna plane to the greatest extent, and reduces the shielding of the receiving antenna 1 to the transmitting antenna 2; c. The strong coupling between the two antennas caused by the close distance is reduced; d. Due to the connection method of metal strips and metal columns, the current path on the dipole arm is increased, which plays a role in increasing the bandwidth. The middle parts of the two dipole antenna arms are bent upward and downward to form an arched structure, which ensures the continuity of the current of the single-arm dipole antenna. On a single-layer board, this design is easy to implement. At the same time, the two boards adopt a cross-slot design in appearance. The top of the lower substrate has a slot equivalent to the thickness of the substrate to facilitate the insertion of the upper substrate. The lower part of the upper substrate has a similar slot to facilitate the cross-placement of the two. The sum of the lengths of the slots of the upper substrate and the lower substrate is equal to the height of the substrate. The depth of the slot of the lower substrate ensures that the radiation arms of the two are at the same horizontal position. The bottom of the two substrates are designed to avoid the feed probe insulator.

[0061] like Figure 5 As shown, the transmitting antenna 2 is composed of four microstrip patch antennas placed on a TSM-DS3 substrate with a thickness of 0.508 mm, and is separated by metal shielding holes to reduce the interference of the scattering field caused by the transmission of surface waves between the transmitting and receiving antenna units on the radiation pattern of adjacent antenna units, and at the same time, to prevent electromagnetic waves from being transmitted through the substrate to adjacent same-frequency and different-frequency antenna units, reduce same-frequency and different-frequency interference, and improve antenna isolation. There are two orthogonal cross-shaped gaps on the substrate of the transmitting antenna 2, which play a role in fixing the receiving antenna 1. The four patches are arranged in a sequentially rotating manner in position to obtain the best axial ratio characteristics. As shown Figure 6 As shown, the transmitting antenna 2 also adopts the G-type probe proximity coupling feeding method to increase the bandwidth. The horizontal branches of the G-type probe proximity coupling feeding structure are placed on the lower layer TSM-DS3 substrate in the XOY direction, and the substrate is placed on the metal cavity and supported by the metal cavity.

[0062] The structure of the metal cavity 3 is as follows Figure 7As shown, the metal cavity 3 has a metal slot gap at the cross-shaped edge for the receiving antenna 1 to be inserted and fixed therein. The transmitting antenna 2 substrate and the metal slot at the cross-shaped edge of the cavity together play a role in positioning and fixing the receiving antenna 1, so there is no need to add additional studs at the edge of the cavity to support and fix the receiving antenna, which reduces the instability of the antenna structure and improves the compactness of the entire system. Figure 8 As shown, steps are set in the four edge cavities to fix the transmitting antenna coupling feed substrate in the cavity by screws. The cavity structure plays a role in feeding transition and supporting the transceiver antenna; on the other hand, it can physically isolate the transceiver feed network signal and increase the antenna isolation.

[0063] The lower layer transceiver antenna differential feed phase shift network 4 is as follows Fig. 9 As shown, the feed network adopts the same nested layout as the radiating surface, and the minimization design of the transceiver feed network is realized under the condition of satisfying the phase and amplitude transmission, which improves the compactness of the whole system. The four transmitting antenna feed networks are rotated in the same order as the patch to obtain the best axial ratio characteristics and reduce the axial ratio drop when scanning to a large angle. Metallized holes are used to isolate the signal of the transceiver unit feed network around each transmitting unit feed network and the receiving unit feed network to avoid the crosstalk of the transceiver feed network signal affecting the isolation and phase. Transmitting antenna 2 adopts differential feeding, and the port phase increases by 90° clockwise in sequence, forming left-hand circular polarization and obtaining the best axial ratio characteristics; the advantage of four-port differential feeding is that its axial ratio characteristics are better than those of dual-port feeding or single-port feeding. Receiving antenna 1 also adopts differential feeding, and the port phase decreases by 90° clockwise in sequence, forming right-hand circular polarization and obtaining the best axial ratio characteristics. At the same time, a low-pass filter is placed on each path of the receiving feed network to filter out the interference of the transmitting path signal on the receiving path signal and improve the isolation between the transmitting and receiving antennas.

[0064] In order to improve the axial ratio characteristics of the proposed co-aperture phased array antenna during scanning, in addition to the sequential rotation arrangement of the single 2×2 basic subarray transmitting antenna 2, each basic subarray is formed into an array according to the following Fig.10 The arrangement is performed in a sequential rotation manner as shown to reduce the decrease in axial ratio during large angle scanning.

[0065] Further, Fig.11 The standing wave of receiving antenna 1 in the whole frequency band can be seen that its standing wave is less than -15dB in the whole working frequency band; Fig.12 This is the standing wave of transmitting antenna 2 in the entire frequency band. It can be seen that in the entire working frequency band, its standing wave is less than -15dB; Fig.13 This is the isolation of the transmitting and receiving antennas within the receiving frequency band. It can be seen that the isolation within the receiving frequency band is less than -25dB; Fig.14This is the isolation of the transmitting and receiving antennas within the transmitting frequency band. It can be seen that within the transmitting frequency band, due to the addition of a low-pass filter, the isolation is less than -64dB.

[0066] Further, Fig.15 Schematic diagram of the 2×4 array of basic subarrays for transmitting and receiving antenna simulation; Fig.16 For the scanning pattern of the receiving antenna basic subarray 2×4 array at the center frequency of 2GHz, when the antenna scans to ±51°, its gain decrease is less than 3.1dB; Fig.17 The 2×4 array of the basic subarray of the receiving antenna is scanned at the center frequency 2GH to the axis ratio of different angles within the range of ±51°. It can be seen that due to the sequential rotation of the basic subarray, its axis ratio is always less than 3dB within the scanning range; Fig.18 The scanning pattern of the 2×4 array of the basic subarray of the transmitting antenna 2 at its center frequency of 3.5 GHz, when the antenna scans to ±51°, its gain decrease is less than 4 dB; Fig.19 The 2×4 array of the basic subarray of the transmitting antenna 2 is scanned at the center frequency 3.5 GHz to the axial ratio values ​​of different angles within the range of ±51°. It can be seen that since the basic subarray adopts a sequential rotation method, its axial ratio value is always less than 1 dB within the scanning range.

[0067] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A compact dual-frequency dual-circular polarization spaceborne common-aperture antenna array, comprising a plurality of basic sub-arrays, characterized in that: The basic subarray includes a low-frequency receiving antenna, a high-frequency transmitting antenna, a metal cavity, a differential feeding phase shifting network for transmitting and receiving antennas, and an antenna support structure, which are connected in sequence from top to bottom. The receiving antenna and the transmitting antenna both adopt differential feeding + Г-type probe proximity coupling feeding.

2. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The receiving and transmitting frequency ratio of the receiving antenna and the transmitting antenna is 2:

1. The transmitting antenna includes four high-frequency transmitting units, and the four high-frequency transmitting units include a low-frequency receiving unit. The four high-frequency transmitting units and one low-frequency receiving unit are combined in a nested manner. The radiation structures of the receiving antenna and the transmitting antenna are arranged in a high-low staggered manner.

3. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The receiving antennas are two dipole antennas. The dipole antennas are made by printing metal strips on the upper and lower layers of a dielectric substrate in the XOZ direction and the YOZ direction, and the metal arms are connected in the middle by through holes. A cross slot design is performed on the dielectric substrate in the XOZ direction and the dielectric substrate in the YOZ direction where the dipole antennas are located. The dielectric substrates are both provided with slots having the same thickness as the substrates. The sum of the slot depths of the dielectric substrate in the XOZ direction and the slot depths of the dielectric substrate in the YOZ direction is equal to the height of the dielectric substrate in the XOZ direction / the dielectric substrate in the YOZ direction. In order to avoid the slot design in the dielectric substrate, the middle part of the dipole antenna on the dielectric substrate in the XOZ direction is bent upward to form an arch, and the middle part of the dipole antenna on the dielectric substrate in the YOZ direction is bent downward to form an arch.

4. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The transmitting antenna includes four microstrip patch antennas, and the radiation patch is a square with cut corners on all four sides.

5. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The G-type probe proximity coupling feeding structure includes two parts, the first part is a horizontal branch and the second part is a vertical branch.

6. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The horizontal branches in the G-type probe proximity coupling feeding structure corresponding to the receiving antenna are placed on the dielectric substrate in the XOZ direction and the YOZ direction; the horizontal branches in the G-type probe proximity coupling feeding structure corresponding to the transmitting antenna are placed on the dielectric substrate in the XOY direction.

7. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 1, characterized in that: The metal cavity is a cube, including four edge square cavities and a cross-shaped cavity in the middle; the four microstrip patch antennas are fixed on the four edge cavities, and steps are provided in the four edge cavities, the steps are connected to the dielectric substrate where the horizontal branches of the G-type probe proximity coupling feeding structure of the transmitting antenna are located, and play a supporting role for the substrate where the transmitting antenna feeding structure is located; the cross-shaped edge of the metal cavity is provided with a metal slot gap, and the receiving antenna is inserted into the transmitting antenna and the slot by plugging for fixing.

8. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 7, characterized in that: A feeding probe insulator is connected to the metal cavity, and the metal probe in the middle of the feeding probe insulator in the cross-shaped cavity is connected to the vertical branch of the G-type probe proximity coupling feeding structure of the receiving antenna by spot welding; the metal probe in the middle of the feeding probe insulator in the four edge cavities is connected to the horizontal branch of the G-type probe proximity coupling feeding structure of the transmitting antenna by spot welding.

9. The compact dual-frequency dual-circular polarization spaceborne common-aperture antenna array according to claim 1, characterized in that: The differential feeding phase shifting network of the transmitting and receiving antenna adopts a nested layout.

10. The compact dual-frequency dual-circular polarization satellite-borne common-aperture antenna array according to claim 2, characterized in that: The port phase of the transmitting antenna increases by 90° clockwise, and the port phase of the receiving antenna decreases by 90° clockwise.

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