Miniature broadband dual-frequency dual-polarization nested common-aperture antenna unit

Abstract

The invention discloses a small broadband dual-frequency dual-polarization nested common-aperture antenna unit, and belongs to the technical field of electromagnetic field antenna design. The antenna comprises an L-band dual-polarized antenna module and S-band dual-polarized antenna modules, the four S-band dual-polarized antenna modules serve as parasitic units and are evenly distributed around the L-band dual-polarized antenna module, and the L-band dual-polarized antenna module is located in the center of the antenna unit. Comprising two single-polarized microstrip dipole antennas which are orthogonally placed in a cross mode, and the antenna unit is divided into four areas through the cross placement mode; and the four S-band dual-polarized antenna modules are uniformly distributed in the center of the four areas as parasitic units. According to the invention, the axial symmetry of the directional diagrams of the L-band and S-band dual-polarized radiation unit and the consistency of the phase center are effectively realized, the high isolation of dual-band and dual-polarization is ensured, and a basis is provided for the lightweight and integrated design of a large-caliber dual-band and dual-polarized antenna.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic field antennas, and in particular relates to a small broadband dual-frequency dual-polarization nested co-aperture antenna unit. Background Art

[0002] With the continuous development of SAR imaging radar technology, new SAR systems have multi-functional and multi-mode application requirements. SAR systems have evolved from single-polarization and single-frequency band to multi-polarization and multi-frequency band, which requires SAR antennas to have multi-frequency and multi-polarization working capabilities. If the antenna arrays of each frequency band and each polarization are designed independently, it will inevitably lead to an exponential increase in the antenna aperture size, equipment quantity and weight, which will eventually bring a heavy burden to the satellite platform. Therefore, how to simultaneously realize the design of multi-frequency and multi-polarization common aperture antennas in one antenna array is of great significance to the engineering implementation of multi-frequency and multi-polarization SAR systems.

[0003] In order to achieve low-cost, lightweight, and large-aperture SAR system design, a multi-frequency, multi-polarization co-aperture nested phased array design is usually adopted for multi-frequency, multi-polarization systems, or a multi-frequency, multi-polarization feed source is used in combination with a reflector antenna design. For the design of a dual-frequency, dual-polarization reflector antenna, it is necessary not only to design an antenna unit with a dual-frequency, dual-polarization co-aperture, but also to have a good axial symmetry in the directional pattern of each antenna unit, so as to ensure the illumination cone of the reflector surface by different polarizations of the antenna unit, thereby ensuring the aperture efficiency and beam width consistency of the dual-polarization reflector antenna. At the same time, in order to make the radiating units of different polarizations and bands located at the focal position of the reflector antenna, it is also necessary to require the consistency of the phase center of the radiating unit when working in different polarizations and different bands. Therefore, a small broadband dual-frequency, dual-polarization, nested co-aperture antenna radiating unit that achieves axial symmetry of the directional pattern and consistency of the phase center of multi-band, multi-polarization is the basis for realizing a lightweight reflector antenna. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a small broadband dual-frequency dual-polarization nested co-aperture antenna unit, which can not only achieve good standing waves and port isolation under broadband conditions, but also achieve axial symmetry of the directional patterns of different polarizations, thereby ensuring the performance of the dual-polarization reflector antenna; by ensuring the consistency of the phase center of the antenna unit in different bands, the antenna aperture utilization and directional pattern performance consistency of the dual-frequency dual-polarization reflector antenna can be achieved. By designing the radiating antenna unit with a small co-aperture, the antenna unit can also be used in the design of phased array antennas.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A small broadband dual-frequency dual-polarization nested co-aperture antenna unit comprises an L-band dual-polarization antenna module and an S-band dual-polarization antenna module. Four S-band dual-polarization antenna modules are uniformly distributed around the L-band dual-polarization antenna module as parasitic units, wherein the L-band dual-polarization antenna module is located at the center of the antenna unit and comprises two cross-orthogonally placed single-polarization microstrip dipole antennas. The cross-placement method divides the antenna unit into four areas; the four S-band dual-polarization antenna modules are uniformly distributed in the center of the four areas as parasitic units.

[0007] Furthermore, the antenna unit also includes a metal back cavity, and the L-band dual-polarization antenna module and the S-band dual-polarization antenna module are located in the metal back cavity formed by a metal wall.

[0008] Furthermore, the two single-polarized microstrip dipole antennas of the L-band dual-polarized antenna module have the same structure, both including a radiation layer, a dielectric layer and a feeding layer arranged in sequence from left to right, and the radiation layer includes a left radiation patch and a right radiation patch, which are evenly distributed on the left and right sides of the dielectric layer, and the two dielectric layers are cross-crossed through the gap between the left radiation patch and the right radiation patch.

[0009] Furthermore, paper honeycombs are used to fix and support two cross-shaped single-polarized microstrip dipole antennas and an S-band antenna module.

[0010] Furthermore, the S-band dual-polarized antenna module includes a first radiation patch, a first dielectric layer, a second radiation patch, a second dielectric layer, a coupling layer, a third dielectric layer, a feeding layer, a fourth dielectric layer, an isolation layer, a fifth dielectric layer, a feeding conversion layer, a sixth dielectric layer, and a ground plane layer stacked in sequence from top to bottom, wherein the slot coupling feeding is located in the feeding layer.

[0011] Further, the coupling layer includes an I-shaped H-polarization coupling slot and an I-shaped V-polarization coupling slot, and the feeding layer includes a rectangular H-polarization feeding point and a rectangular V-polarization feeding point corresponding to each polarization coupling slot.

[0012] Furthermore, the H polarization coupling slot and the V polarization coupling slot are placed orthogonally.

[0013] Furthermore, the top of the radiation layer of the L-band dual-polarization antenna module is not higher than the coupling layer of the S-band dual-polarization antenna module.

[0014] Furthermore, the feeding layer of the S-band dual-polarized antenna module first converts the rectangular H-polarized feeding point and the rectangular V-polarized feeding point to the central area of ​​the microstrip antenna of the S-band dual-polarized antenna module, and then transfers them to the bottom of the L-band dual-polarized antenna module through a coaxial structure, and the feeding points of the L-band and S-band are both located at the bottom.

[0015] Furthermore, the ends of the H-polarized and V-polarized strip lines are directly connected to the coupling layer through short circuits, and the feeding of the two polarizations is completed through the H-shaped slot; the strip lines of the two polarized feeding layers are connected to the feeding point after conversion, and the impedance matching of the feeding point is completed through impedance transformation during the conversion process. The conversion structure of the S-band dual-polarized antenna unit uniformly converts the H-polarized and V-polarized feeding ports to the center position of the S-band antenna unit for feeding.

[0016] Furthermore, the S-band dual-polarized antenna module uses vias to connect the edges of the coupling layer, the isolation layer, and the ground plane layer together to form a closed structure.

[0017] Furthermore, the S-band dual-polarized antenna module uses a via hole at the center of the coupling layer to form an isolation wall to isolate the H polarization from the V polarization.

[0018] Furthermore, in the S-band dual-polarized antenna module, the H-polarized and V-polarized strip lines are connected by vias in the feed conversion layer to form two completely closed feed structures.

[0019] The beneficial effects of the present invention are:

[0020] 1) For the L-band antenna unit module, a cross-shaped microstrip dipole radiating unit and a parasitic patch are placed to realize a small broadband L-band dual-polarization antenna unit while improving the axial symmetry of the L-band dual-polarization pattern and the consistency of the phase center at different frequencies, meeting the design requirements of the reflector antenna feed;

[0021] 2) The S-band antenna unit module adopts a feed conversion structure to convert the feeding points of the two polarizations of the S-band to the center of the microstrip antenna, and uses the S-band antenna unit module as an L-band parasitic patch. While meeting the performance of the S-band antenna unit, the performance of the L-band antenna unit is also guaranteed, ultimately realizing a dual-frequency, dual-polarization, co-aperture nested design of one L-band and four S-band antenna units.

[0022] 3) Add isolation walls around the L-band antenna and isolate the S-band dual-polarization antenna module. On the basis of realizing the common aperture of the dual-frequency dual-polarization antenna, dual-frequency dual-polarization isolation is achieved, ensuring the electrical performance of the dual-frequency common aperture antenna.

[0023] 4) The dual-frequency common-aperture antenna unit designed through the above design is used as a reflector feed source, meeting the needs of a dual-frequency dual-polarization shared reflector antenna.

[0024] The present invention ensures the axial symmetry of the antenna unit pattern on the E-plane and the H-plane, as well as the consistency of the phase center, through a two-band fusion design, and realizes a lightweight and integrated design of a dual-frequency dual-polarization antenna, thereby reducing the antenna weight and system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the antenna structure of the present invention, wherein (a) is a top view and (b) is a side view;

[0026] Figure 2 The figure is a composition diagram of the L-band single-polarized antenna of the present invention, wherein (a) is a front view and (b) is a side view;

[0027] Figure 3 The structure diagram of the L-band dual-polarized antenna module of the present invention, wherein (a) is a front view and (b) is a side view;

[0028] Figure 4 The figure is a composition diagram of the S-band dual-polarized antenna module of the present invention, wherein (a) is a top view and (b) is a side view;

[0029] Figure 5 The S-band feeding port conversion structure of the present invention;

[0030] Figure 6 The structure diagram of the S-band dual-polarized antenna module of the present invention, wherein (a) is a top view and (b) is a side view;

[0031] Figure 7 The structure diagram of the L-band and S-band nested co-aperture antenna of the present invention, wherein (a) is a top view and (b) is a side view;

[0032] Figure 8 The L-band dual-polarization antenna unit port characteristics of the present invention, wherein (a) is the antenna port standing wave curve, and (b) is the antenna port isolation curve;

[0033] Fig. 9 This is the L-band dual-polarization antenna unit pattern result of the present invention;

[0034] Fig.10 The port characteristics of the S-band dual-polarized antenna unit of the present invention, wherein (a) is the standing wave curve of the antenna port, and (b) is the isolation curve of the antenna port;

[0035] Fig.11 It is the directional pattern result of the S-band dual-polarized antenna unit of the present invention;

[0036] FIG. 12( a ) is a result of the radiation pattern of the H-polarized reflector antenna at different frequencies in the L-band of the present invention;

[0037] FIG12( b ) is the radiation pattern results of the V-polarized reflector antenna at different frequencies in the L-band of the present invention;

[0038] FIG. 12( c ) is a result of the radiation pattern of the reflector antenna with different polarizations in the L band of the present invention;

[0039] FIG. 13( a ) is a result of the radiation pattern of the H-polarized reflector antenna at different frequencies in the S band of the present invention;

[0040] FIG13( b ) is the radiation pattern results of the V-polarized reflector antenna at different frequencies in the S band of the present invention;

[0041] FIG. 13( c ) is the radiation pattern result of the S-band reflector antenna with different polarizations according to the present invention. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0043] The present invention mentions a small broadband dual-frequency dual-polarized nested co-aperture antenna unit, the antenna unit structure consists of an L-band dual-polarized antenna module and four S-band dual-polarized antenna modules, wherein the S-band dual-polarized antenna module consists of a dual-polarized microstrip antenna, and the L-band dual-polarized antenna module consists of two cross-shaped microstrip dipole antenna units. The L-band dual-polarized antenna module is located at the center of the antenna structure, and the cross-shaped L-band dual-polarized antenna modules divide the entire antenna structure into four areas. The S-band dual-polarized antenna modules are respectively located at the center of the four areas. The unit spacing between the four S-band dual-polarized antenna modules is 70mm×70mm, wherein the antenna part of the S-band dual-polarized antenna module is located on the upper layer of the L-band dual-polarized antenna module, and the top position of the L-band dual-polarized antenna module is basically consistent with the coupling layer position of the S-band dual-polarized antenna module, and the position can be appropriately adjusted according to the electrical performance indicators. The microstrip antenna unit of the S-band dual-polarized antenna module converts the feeding point to the center area of ​​the microstrip antenna through the feed conversion layer, and then transfers it to the bottom of the L-band through the coaxial structure. Finally, the feeding points of the L-band and S-band are both located at the bottom of the antenna unit. A metal wall is used around the entire antenna to form a metal back cavity to reduce the electromagnetic coupling between multiple dual-frequency dual-polarized antenna units. The schematic diagram of the entire antenna unit structure is shown in the figure. Figure 1 As shown in (a)-(b).

[0044] Among them, the L-band dual-polarized antenna module adopts two single-polarized microstrip dipole antennas to be orthogonally placed. The orthogonal refers to the vertical cross-orthogonal placement of the dielectric substrate where the microstrip dipole antenna is located, and is placed in a metal cavity. This design realizes the miniaturization of the L-band dual-polarized antenna, and obtains good impedance matching so that the L-band antenna has good electrical performance; the four S-band dual-polarized antenna modules embedded around the L-band dual-polarized antenna module can not only achieve good electrical performance of the S-band by making full use of the frequency relationship between the L-band and the S-band, and reasonably designing the L-band and S-band antenna module models, but also can be used as a parasitic structure of the L-band to improve the L-band antenna radiation pattern performance. Among them, the metal back cavity of the L-band antenna module can not only reduce the coupling between multiple L-band antenna units, but also form an equivalent metal cavity with the radiation unit placed orthogonally in the L-band, reducing the coupling between the four S-band antenna modules.

[0045] The physical structure and simulation analysis results of the L-band and S-band antennas are described below.

[0046] 1. Antenna design

[0047] 1.1. L-band dual-polarization antenna module design

[0048] The L-band dual-polarized antenna module is mainly composed of two single-polarized microstrip dipole radiating units arranged in a cross-shaped manner. The cross-shaped arrangement and metal back cavity design achieve good electrical performance of the L-band dual-polarized antenna. The schematic diagram of the single-polarized microstrip dipole radiating unit structure is shown in the figure. Figure 2 As shown in (a)-(b), each single-polarized microstrip dipole radiating unit consists of three layers, referring to Figure 2 In (b), from left to right, they are: radiation layer, dielectric layer and feeding layer. Each radiation layer includes two radiation patches, and the two dielectric layers are vertically crossed through the gap between the two radiation patches.

[0049] For ordinary cross-arranged microstrip dipole antenna units, the axial symmetry of each polarized unit pattern is poor (the E-plane and H-plane antenna patterns are quite different), and the phase center heights of different frequencies are inconsistent. Therefore, when ordinary cross-arranged antenna units are used as feed sources for reflector antennas, the dual-polarized antenna direction of the reflector antenna cannot be guaranteed. Figure 1consistency; at the same time, the inconsistency of phase centers at different frequencies leads to the deterioration of the reflector antenna gain, which makes it impossible to ensure the optimal aperture utilization of the reflector within the working bandwidth. In order to meet the reflector antenna's demand for L-band feed, four parasitic patches are added on the basis of the cross-arranged microstrip dipole antenna model to improve the axial symmetry and phase center stability of each polarization pattern of the L-band dual-polarized antenna unit. In the entire antenna structure, the S-band dual-polarized antenna module will serve as an L-band parasitic patch to achieve the electrical performance of the L-band antenna. In order to ensure that the entire antenna has good structural support and reduce the weight of the antenna, paper honeycombs are used to provide structural support for the L-band and S-band antenna modules, thereby ensuring the polarization performance and structural strength of the L-band antenna. The L-band dual-polarized antenna structure is as follows Figure 3 shown.

[0050] The L-band antenna module is directly connected to the microstrip line of the feed layer through a 50-ohm coaxial connector. The radiation layer and the feed layer form a microstrip line, which is short-circuited with the radiation patch 1 at the end of the microstrip line through a short-circuit pin. The microstrip line of the feed layer is connected through a quarter impedance transformer to ensure that the antenna achieves good impedance matching within a larger bandwidth. By adjusting the length of the top radiation patch, the height of the L-band antenna unit can be reduced, thereby achieving a low profile and lightweight L-band antenna.

[0051] The final optimized model and structural parameters are as follows Figure 3 (a)-(b) show the main dimensions of the L-band antenna unit. The L-band dual-polarization antenna unit size is 140mm. 140mm 42.4mm, parasitic patch size is 50mm 50mm (same as the S-band coupling layer size), four parasitic patches are symmetrically distributed, and the position of a single parasitic patch is 35mm 35mm 39.4mm.

[0052] 1.2. Design of S-band dual-polarized antenna module;

[0053] The S-band dual-polarized antenna module adopts a low-profile dual-polarized microstrip patch antenna. The structural diagram of the antenna unit is shown in the figure. Figure 4 As shown in (a)-(b) in the figure, the S-band antenna module consists of 9 layers. Figure 4As shown in (b), the radiation patch S1, the first dielectric layer, the radiation patch S2, the second dielectric layer, the coupling layer, the third dielectric layer, the feeding layer, the fourth dielectric layer, and the ground plane are stacked in sequence from top to bottom. The H polarization coupling slot and the V polarization coupling slot both use I-shaped slots and are located in the coupling layer. The isolation between the two polarizations is achieved by orthogonally placing the H polarization coupling slot and the V polarization coupling slot; the H polarization feeding and the V polarization feeding are located in the feeding layer between the third dielectric layer and the fourth dielectric layer, and the coupling slots of the two polarizations are coupled and fed in the form of strip lines.

[0054] In order to realize the co-aperture nested design of L-band and S-band dual-polarized antennas, and use the S-band antenna module as a parasitic patch of the L-band, one L-band antenna module and four S-band antenna modules form an L-band and S-band nested co-aperture dual-polarized antenna unit.

[0055] Since the feeding point of the microstrip patch antenna unit is usually located at the edge of the microstrip antenna, the S-band feeding port will affect the electrical performance of the L-band antenna. Therefore, it is necessary to design a feeding conversion structure to convert the S-band feeding port to the center of the microstrip antenna to reduce the impact of the S-band feeding on the L-band antenna performance. Figure 5 shown.

[0056] The ends of the H-polarized and V-polarized strip lines are directly connected to the coupling layer through short circuits, and the coupled feeding of the two polarizations is completed through the I-type slot. The impedance matching of the feeding is completed through impedance transformation during the conversion process of the two polarized strip lines. The conversion structure of the S-band dual-polarized antenna unit uniformly converts the H-polarized and V-polarized feeding ports to the center position of the S-band antenna unit for feeding.

[0057] The L-band and S-band are co-aperture nested designs. The electromagnetic signals between the two bands will interfere with each other, resulting in poor antenna performance. At the same time, the complex feed conversion structure of the S-band will cause mutual coupling between the two polarizations of the S-band, thereby reducing the polarization isolation of the S-band antenna. Therefore, it is necessary to isolate the antenna to enhance the signal isolation between the two bands and different polarizations. The unit structure of the S-band dual-polarization antenna with isolation design is shown in the figure. Figure 6 As shown in (a)-(b).

[0058] In order to improve the isolation between the L-band and S-band antennas, vias are used at the edge of the S-band antenna module to connect the metal layer between the coupling layer and the ground plane to form a closed structure. The electromagnetic signal is only input through the feeding point and output through the I-type slot coupling, which finally achieves the isolation of the L-band signal. At the same time, vias are used in the middle position of the S-band antenna module to add an isolation wall between the coupling layer and the ground plane, completely isolating the two polarization feeding structures of the S-band to improve the isolation between the two polarizations. A layer of ground is added between the I-type coupling feeding layer and the stripline conversion layer as an isolation layer, and vertical interconnection is performed through vias to reduce the coupling of the S-band dual-polarization feeding structure during the internal conversion process. In the conversion layer, the S-band feed adopts a closed design, completely isolating the feeding structure between the two polarizations to improve the isolation between different polarizations and ensure that the S-band antenna unit has good radiation characteristics.

[0059] The final size of the S-band antenna unit is 50mm through optimized design 50mm 12.3mm, antenna structure as Figure 6 As shown in (a)-(b).

[0060] 1.3. L-band and S-band nested co-aperture design

[0061] The L-band and S-band nested co-aperture antenna structures are as follows: Figure 7 As shown in (a)-(b), an L-band antenna module is combined with four S-band antenna modules to form a nested co-aperture integrated dual-frequency dual-polarization antenna unit, where the spacing between the S-band antennas is 70 mm. 70mm. The L-band antenna uses a microstrip dipole antenna and an S-band antenna module as the antenna form of a parasitic patch; the S-band uses a microstrip patch antenna unit form with a feed conversion design and an isolation design.

[0062] In order to reduce the mutual influence between L-band and S-band antennas, the S-band antenna module is located on the top of the L-band antenna. The L-band cross-microstrip dipole unit and the surrounding metal back cavity isolate the single S-band antenna equivalently, effectively reducing the coupling between S-band antennas. At the same time, the S-band can also be used as an L-band parasitic patch, so that the L-band and S-band have the same phase center height, ensuring the ability of the dual-band to share the same aperture and reflective surface.

[0063] Detailed parameters such as Figure 7 As shown, the metal back cavity height is 36.9mm, the S-band antenna is located at 39.4mm, the L-band microstrip dipole antenna length is 97mm, the S-band antenna height is 12.3mm, and the entire antenna size is 140mm 140mm 51.7mm.

[0064] The L-band uses paper honeycombs to fix and support the cross-microstrip dipole antenna, and the structure between the S-band antenna coupling layer and the ground plane is designed with a microstrip circuit board. The integrated design effectively reduces the weight of the L-band and S-band integrated co-aperture nested units. The axial symmetry and co-phase center height of the dual-band dual-polarization antenna unit pattern are guaranteed, and the requirements of the dual-band dual-polarization co-aperture shared reflection surface are met, ensuring the performance of the dual-band dual-polarization reflection surface antenna. The shared reflection surface further realizes the lightweight design of the antenna system, effectively reducing the weight of the antenna system.

[0065] 2. Performance analysis results

[0066] 2.1, L-band results;

[0067] The voltage standing wave ratio VSWR of the two polarizations of the L-band dual-polarization antenna is Figure 8 As given in (a), the isolation between the two polarization ports is Figure 8 As shown in (b), it can be seen that the two polarizations are both less than 1.5 in the frequency range of 1.15GHz~1.4GHz, and the polarization isolation of the two ports is less than -40dB.

[0068] The L-band antenna unit pattern is as follows Fig. 9 As shown in (a)-(b), the radiation pattern has good axial symmetry and good consistency between the two polarizations. At 1.15 GHz, 1.25 GHz, 1.35 GHz and 1.4 GHz, the half-power beamwidths of the H-plane and E-plane of H polarization are (86°, 86°, 87° and 85°) and (86°, 86°, 87° and 85°), respectively, and the half-power beamwidths of the H-plane and E-plane of V polarization are (86°, 86°, 87° and 85°) and (86°, 86°, 87° and 85°), respectively.

[0069] 2.2, S band results;

[0070] The voltage standing wave ratio VSWR of the two polarizations of the S-band antenna is Fig.10 As given in (a), the isolation between the two polarization ports is Fig.10 As shown in (b), it can be seen that the two polarizations are less than 1.5 in the frequency range of 3.05 GHz to 3.35 GHz, and the port isolation of the two polarizations is less than -35 dB.

[0071] The S-band antenna unit pattern is as follows Fig.11As shown, the radiation pattern has good axial symmetry and the two polarizations have good consistency. At 3.05 GHz, 3.20 GHz and 3.35 GHz, the half-power beamwidths of the H-plane and E-plane of H polarization are (73°, 70° and 68°) and (71°, 63° and 63°), respectively, and the half-power beamwidths of the H-plane and E-plane of V polarization are (70°, 70° and 67°) and (69°, 63° and 64°), respectively. The two polarizations have good consistency and symmetry.

[0072] 2.3. Results of dual polarization shared reflection surface;

[0073] The dual-frequency dual-polarization common aperture antenna unit is used as the feed source of the reflector to form a dual-frequency dual-polarization reflector antenna. The performance of the reflector antenna pattern is shown in Figures 12 and 13 after simulation analysis.

[0074] Figure 12 (a) shows the antenna radiation pattern of the H-polarized reflector surface with Phi=0 cut plane in the L band at different frequencies. It can be seen from the figure that the beam width and gain of the radiation pattern at different frequencies are consistent, indicating that the phase center and beam width of the co-aperture antenna unit at different frequencies and H polarization are consistent.

[0075] Figure 12 (b) shows the antenna radiation pattern of the Phi=0 section V polarization reflector antenna in the L band at different frequencies. It can be seen from the figure that the beam width and gain of the radiation pattern at different frequencies are consistent, indicating that the phase center and beam width of the co-aperture antenna unit at different frequencies V polarization are consistent.

[0076] Figure 12 (c) shows the radiation pattern results of the reflector antenna with different polarizations and different cut planes at the center frequency in the L band. It can be seen from the figure that the radiation pattern beam width and gain of the two polarizations and the two cut planes are consistent, indicating that the co-aperture antenna unit has good axial symmetry of the radiation pattern in the L band and the two polarizations have consistent phase center and beam width.

[0077] Figure 13 (a) shows the S-band antenna radiation pattern results of the Phi=0 cut plane H polarization reflector at different frequencies. It can be seen from the figure that the beam width and gain of the radiation pattern at different frequencies are consistent, indicating that the phase center and beam width of the co-aperture antenna unit at different frequencies H polarization are consistent.

[0078] Figure 13 (b) shows the S-band antenna radiation pattern results of the Phi=0 section V-polarized reflector at different frequencies. It can be seen from the figure that the beam width and gain of the radiation pattern at different frequencies are consistent, indicating that the phase center and beam width of the co-aperture antenna unit at different frequencies V polarization are consistent.

[0079] Figure 13 (c) shows the radiation pattern results of the reflector antenna with different polarizations and different cut planes at the center frequency in the S band. It can be seen from the figure that the radiation pattern beam width and gain of the two polarizations and the two cut planes are consistent, indicating that the co-aperture antenna unit has quantized radiation pattern axial symmetry in the S band and the two polarizations have consistent phase center and unit beam width.

[0080] Through the above simulation analysis results, it can be seen that the dual-frequency dual-polarization co-aperture nested antenna unit can meet the electrical performance requirements of the reflector feed, and can achieve the design requirements of the co-aperture, high integration, and lightweight reflector feed. At the same time, the miniaturized size of the dual-frequency dual-polarization co-aperture nested unit can meet the design requirements of the phased array antenna.

[0081] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A small broadband dual-frequency dual-polarization nested co-aperture antenna unit, characterized in that: The invention comprises an L-band dual-polarization antenna module and an S-band dual-polarization antenna module. Four S-band dual-polarization antenna modules are uniformly distributed around the L-band dual-polarization antenna module as parasitic units. The L-band dual-polarization antenna module is located at the center of the antenna unit and comprises two cross-orthogonally placed single-polarization microstrip dipole antennas. The cross-placement method divides the antenna unit into four areas. The four S-band dual-polarization antenna modules are uniformly distributed in the center of the four areas as parasitic units.

2. A small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 1, characterized in that: The antenna unit further comprises a metal back cavity, and the L-band dual-polarization antenna module and the S-band dual-polarization antenna module are located in the metal back cavity formed by a metal enclosure.

3. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 1, characterized in that: The two single-polarized microstrip dipole antennas of the L-band dual-polarized antenna module have the same structure, and both include a radiation layer, a dielectric layer and a feeding layer arranged from left to right. The radiation layer includes a left radiation patch and a right radiation patch, which are evenly distributed on the left and right sides of the dielectric layer, and the two dielectric layers are cross-crossed through the gap between the left radiation patch and the right radiation patch.

4. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 3, characterized in that: Paper honeycombs are used to fix and support two cross-shaped single-polarized microstrip dipole antennas and the S-band antenna module.

5. A small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 4, characterized in that: The S-band dual-polarized antenna module includes a first radiation patch, a first dielectric layer, a second radiation patch, a second dielectric layer, a coupling layer, a third dielectric layer, a feeding layer, a fourth dielectric layer, an isolation layer, a fifth dielectric layer, a feeding conversion layer, a sixth dielectric layer, and a ground plane layer stacked in sequence from top to bottom, wherein the slot coupling feeding is located in the feeding layer.

6. A small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, characterized in that: The coupling layer includes an I-shaped H-polarization coupling slot and an I-shaped V-polarization coupling slot, and the feeding layer includes a rectangular H-polarization feeding point and a rectangular V-polarization feeding point corresponding to each polarization coupling slot.

7. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, characterized in that: The H polarization coupling slot and the V polarization coupling slot are placed orthogonally.

8. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 6, characterized in that: The feeding layer of the S-band dual-polarized antenna module first converts the rectangular H-polarized feeding point and the rectangular V-polarized feeding point to the central area of ​​the microstrip antenna of the S-band dual-polarized antenna module, and then transfers them to the bottom of the L-band dual-polarized antenna module through a coaxial structure. The feeding points of the L-band and S-band are both located at the bottom.

9. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, characterized in that: The S-band dual-polarized antenna module uses vias to connect the edges of the coupling layer, the isolation layer, and the ground plane layer together to form a closed structure.

10. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, characterized in that: The S-band dual-polarized antenna module uses a via hole at the center of the coupling layer to form an isolation wall to isolate the H polarization and the V polarization.

11. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, characterized in that: The S-band dual-polarized antenna module uses vias in the feed conversion layer to form two completely closed feeding structures with H-polarized and V-polarized strip lines.

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