A small broadband dual-frequency dual-polarized nested co-caliber antenna unit

Abstract

The application discloses a small-sized broadband dual-frequency dual-polarized nested co-caliber antenna unit and belongs to the technical field of electromagnetic field antenna design. The antenna comprises an L-wave dual-polarized antenna module and an S-wave dual-polarized antenna module; four S-wave dual-polarized antenna modules are evenly distributed around the L-wave dual-polarized antenna module as parasitic units; the L-wave dual-polarized antenna module is located at the center of the antenna unit and comprises two cross-orthogonal single-polarized microstrip dipole antennas; the cross-arrangement mode divides the antenna unit into four areas; and the four S-wave dual-polarized antenna modules are evenly distributed at the central positions of the four areas as parasitic units. The application effectively realizes the axial symmetry of the L-wave and S-wave dual-polarized radiation unit patterns and the consistency of the phase centers, guarantees the high isolation of the dual-frequency dual-polarization, and provides a basis for the lightweight and integrated design of the large-caliber dual-frequency dual-polarized antenna.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic field antennas, and particularly relates to a small-sized wideband dual-frequency dual-polarized nested co-caliber antenna unit. BACKGROUND

[0002] With the continuous development of SAR imaging radar technology, new system SAR systems have multi-functional and multi-mode application requirements. SAR systems have developed from single polarization and single frequency band to multi-polarization and multi-frequency band, and accordingly require SAR antennas to have multi-frequency and multi-polarization working capabilities. If each frequency band and each polarization antenna array is independently designed, the antenna aperture size, equipment quantity and weight will inevitably increase exponentially, which finally brings a heavy burden to the satellite platform. Therefore, how to simultaneously realize multi-frequency and multi-polarization co-caliber antenna design in one antenna array has important significance for the engineering implementation of multi-frequency and multi-polarization SAR systems.

[0003] In order to realize low-cost, lightweight and large-aperture SAR system design, for multi-frequency and multi-polarization systems, a multi-frequency and multi-polarization co-caliber nested phased array design is usually adopted, or a multi-frequency and multi-polarization feed source is used in combination with a reflector antenna design. For dual-frequency and dual-polarized reflector antenna design, not only an antenna unit with dual-frequency and dual-polarized co-caliber needs to be designed, but also the directional pattern of each antenna unit needs to have good axial symmetry, so as to ensure that the illumination cone of the antenna unit to the reflector is different for different polarizations, thereby ensuring the consistency of the aperture efficiency and the beam width of the dual-polarized reflector antenna. At the same time, in order to make the radiation units of different polarizations and wave bands located at the focal point position of the reflector antenna, the consistency of the phase centers of the radiation units in different polarizations and different wave bands needs to be ensured. Therefore, the realization of a small-sized wideband dual-frequency dual-polarized nested co-caliber antenna radiation unit with directional pattern axial symmetry and multi-band multi-polarization phase center consistency is the basis for realizing a lightweight reflector antenna. SUMMARY

[0004] To solve the above technical problems, the application provides a small-sized wideband dual-frequency dual-polarized nested co-caliber antenna unit, which can not only realize good standing wave and port isolation under wideband conditions, but also realize directional pattern axial symmetry of different polarizations, thereby ensuring the performance of the dual-polarized reflector antenna. By ensuring the consistency of the phase centers of the antenna units in different wave bands, the consistency of the antenna aperture utilization rate and the directional pattern performance of the dual-frequency and dual-polarized reflector antenna can be realized. By small-sized co-caliber design of the radiation antenna unit, the antenna unit can also be used for phased array antenna design.

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

[0006] The application discloses a small-sized broadband dual-frequency dual-polarized nested co-caliber antenna unit, which comprises an L-band dual-polarized antenna module and an S-band dual-polarized antenna module, and four S-band dual-polarized antenna modules as parasitic units are uniformly distributed around the L-band dual-polarized antenna module.

[0007] Further, the antenna unit further comprises a metal back cavity, and the L-band dual-polarized antenna module and the S-band dual-polarized antenna module are located in the metal back cavity formed by the metal wall.

[0008] Further, the two single-polarized microstrip dipole antennas of the L-band dual-polarized antenna module are identical in structure and each comprises, in sequence from left to right, a radiation layer, a dielectric layer and a feeding layer, the radiation layer comprises left and right radiation patches which are uniformly distributed on the left and right sides of the dielectric layer, and the two dielectric layers are cross-connected through a gap between the left and right radiation patches.

[0009] Further, paper honeycomb is adopted to fix and support the two single-polarized microstrip dipole antennas and the S-band antenna module which are cross-connected.

[0010] Further, the S-band dual-polarized antenna module comprises, in sequence from top to bottom, 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, wherein a gap coupling feeding is located on the feeding layer.

[0011] Further, the coupling layer comprises an I-shaped H-polarized coupling gap and an I-shaped V-polarized coupling gap, and the feeding layer comprises a rectangular H-polarized feeding point and a rectangular V-polarized feeding point which correspond to each polarized coupling gap.

[0012] Further, the H-polarized coupling gap and the V-polarized coupling gap are cross-connected.

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

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

[0015] Further, the ends of the H-polarized and V-polarized striplines are connected together by shorting and directly connected to the coupling layer, and the feeding of the two polarizations is completed by the H-type slot; the striplines of the two polarization feeding layers are connected to the feeding points after conversion, and the impedance matching of the feeding points is completed by impedance transformation in the conversion process. The conversion structure of the S-band dual-polarized antenna unit converts the H-polarization and V-polarization feeding ports to the center position of the S-band antenna unit for feeding.

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

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

[0018] Further, the S-band dual-polarized antenna module uses a via to form two completely closed feeding structures for the H-polarized and V-polarized striplines in the feeding conversion layer.

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

[0020] 1) For the L-band antenna unit module, the microstrip dipole radiating element and the parasitic patch are placed in a cross shape, which realizes a small wideband L-band dual-polarized antenna unit, improves the axial symmetry of the L-band dual-polarized pattern and the consistency of the phase center at different frequencies, and meets the design requirements of the reflector antenna feed.

[0021] 2) The S-band antenna unit module uses a feeding conversion structure to convert the S-band two-polarized feeding points to the center of the microstrip antenna, and uses the S-band antenna unit module as an L-band parasitic patch, which meets the performance of the S-band antenna unit while ensuring the performance of the L-band antenna unit, and finally realizes a dual-band dual-polarized co-axial nested design of one L-band and four S-band antenna units.

[0022] 3) The isolation wall is added around the L-band antenna, and the S-band dual-polarized antenna module is isolated, which realizes dual-band dual-polarized isolation on the basis of dual-band dual-polarized co-axial, and ensures the electrical performance of the dual-band co-axial antenna.

[0023] 4) The dual-band co-axial antenna unit design realized by the above design is used as a reflector feed, which meets the requirements of dual-band dual-polarized co-reflecting surface antenna.

[0024] The present application ensures the axial symmetry of the antenna unit pattern in the E-plane and the H-plane, and the consistency of the phase center by two-band fusion design, realizes the lightweight and integrated design of dual-band dual-polarized antenna, and thus reduces the weight of the antenna and the complexity of the system. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0029] Figure 5 is a schematic diagram of the S-band feed port conversion structure of the present application;

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

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

[0032] Figure 8 is a schematic diagram of the L-band dual-polarized antenna unit port characteristics of the present application, wherein (a) is an antenna port standing wave curve and (b) is an antenna port isolation curve;

[0033] Figure 9 is a schematic diagram of the L-band dual-polarized antenna unit pattern results of the present application;

[0034] Figure 10 is a schematic diagram of the S-band dual-polarized antenna unit port characteristics of the present application, wherein (a) is an antenna port standing wave curve and (b) is an antenna port isolation curve;

[0035] Figure 11 is a schematic diagram of the S-band dual-polarized antenna unit pattern results of the present application;

[0036] Fig. 12(a) is a schematic diagram of the L-band different frequency H-polarized reflector antenna pattern results of the present application;

[0037] Fig. 12(b) is a schematic diagram of the L-band different frequency V-polarized reflector antenna pattern results of the present application;

[0038] Fig. 12(c) is a schematic diagram of the L-band different polarization reflector antenna pattern results of the present application;

[0039] Fig. 13(a) is the S-band different frequency H-polarized reflector antenna pattern result of the present application;

[0040] Fig. 13(b) is the S-band different frequency V-polarized reflector antenna pattern result of the present application;

[0041] Fig. 13(c) is the S-band different polarization reflector antenna pattern result of the present application. DETAILED DESCRIPTION

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

[0043] The small broadband dual-frequency dual-polarized nested co-caliber antenna unit mentioned in the present application is composed of an L-band dual-polarized antenna module and four S-band dual-polarized antenna modules, wherein the S-band dual-polarized antenna module is composed of a dual-polarized microstrip antenna, and the L-band dual-polarized antenna module is composed of two cross microstrip dipole antenna units. The L-band dual-polarized antenna module is located at the center of the antenna structure, and the cross-placed L-band dual-polarized antenna module divides 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 at 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. This position can be adjusted according to the electrical performance index. The microstrip antenna unit of the S-band dual-polarized antenna module converts the feed point to the center area of the microstrip antenna through the feed conversion layer, and then transfers to the bottom of the L-band through the coaxial structure. Finally, the feed points of the L-band and the S-band are located at the bottom of the antenna unit. A metal back cavity is formed around the entire antenna to reduce the electromagnetic coupling between multiple dual-frequency dual-polarized antenna units. The entire antenna unit structure composition diagram is shown in Figure 1 (a)-(b).

[0044] The L-band dual-polarized antenna module is orthogonally arranged by two single-polarized microstrip dipole antennas, the orthogonality refers to the vertical cross orthogonality of the dielectric substrate on which the microstrip dipole antennas are arranged, and the microstrip dipole antennas are arranged in a metal cavity, so that the L-band dual-polarized antenna is miniaturized, and good impedance matching is obtained, 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 realize good electrical performance of the S-band, but also improve the L-band antenna pattern performance as a parasitic structure of the L-band, by fully utilizing the frequency relationship between the L-band and the S-band and reasonably designing the L-band and S-band antenna module models. The metal back cavity of the L-band antenna module can not only reduce the coupling between the multiple L-band antenna units, but also form an equivalent metal cavity with the orthogonally arranged radiation units of the L-band, thereby reducing the coupling between the four S-band antenna modules.

[0045] The L-band and S-band antenna physical structures and simulation analysis results are described below.

[0046] 1. Antenna design

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

[0048] The L-band dual-polarized antenna module is mainly composed of two single-polarized microstrip dipole radiation units arranged in a cross shape, and the cross arrangement and the metal back cavity design realize good electrical performance of the L-band dual-polarized antenna. The structure diagram of the single-polarized microstrip dipole radiation unit is shown in Figure 2 (a) and (b) of the accompanying drawings, each single-polarized microstrip dipole radiation unit is composed of three layers, as shown in Figure 2 (b), from left to right: radiation layer, dielectric layer and feed layer. Each radiation layer includes two radiation patches, and the two dielectric layers are vertically cross-shaped through the gap between the two radiation patches.

[0049] For a common cross-arranged microstrip dipole antenna unit, the axial symmetry of each polarized unit is poor (the difference between the E-plane and H-plane antenna patterns is large), and the phase center heights of different frequencies are inconsistent. Therefore, when the common cross-arranged antenna unit is used as a feed source of a reflector antenna, it is difficult to ensure the dual-polarized antenna pattern of the reflector antenna. Figure 1The consistency of the phase center at different frequencies leads to the deterioration of the gain of the reflector antenna, so that the optimal aperture utilization of the reflector cannot be guaranteed within the operating bandwidth. In order to meet the requirements of the L-band feed for the reflector antenna, four parasitic patches are added to the model of the cross-shaped microstrip dipole antenna to improve the axial symmetry and stability of the phase center of the L-band dual-polarized antenna element in each polarization direction. The S-band dual-polarized antenna module in the entire antenna structure will act as a parasitic patch for the L-band to realize the electrical performance of the L-band antenna. In order to ensure that the entire antenna has good structural support and reduces the weight of the antenna, paper honeycomb is used to support the structure of the L-band and S-band antenna modules, so as to ensure the polarization performance and structural strength of the L-band antenna. The structure of the L-band dual-polarized antenna is shown in Figure 3 .

[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, and the microstrip line at the end is short-circuited to the radiation patch 1 through a short-circuit pin. The microstrip line of the feed layer is connected to the antenna through a quarter-wave impedance transformer to ensure good impedance matching of the antenna within a large bandwidth. By adjusting the length of the top radiation patch, the height of the L-band antenna element is reduced, thereby realizing the low profile and light weight of the L-band antenna.

[0051] The final optimized model and structure parameters are shown in Figure 3 (a)-(b), the main dimensions of the L-band antenna element are given, the size of the L-band dual-polarized antenna element is 140mm 140mm 42.4mm, the size of the parasitic patch is 50mm 50mm (consistent with the size of the S-band coupling layer), the four parasitic patches are symmetrically distributed, and the position of a single parasitic patch is 35mm 35mm 39.4mm.

[0052] 1.2, S-band dual-polarized antenna module design;

[0053] The S-band dual-polarized antenna module adopts a low-profile dual-polarized microstrip patch antenna form, and the structure diagram of the antenna element is shown in Figure 4 (a)-(b). The S-band antenna module is composed of 9 layers as shown in Figure 4As shown in FIG. 2 (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 feed layer, the fourth dielectric layer and the ground plane are sequentially stacked from top to bottom. The H-polarized coupling slot and the V-polarized coupling slot are both I-shaped slots and are located in the coupling layer. The isolation between the two polarizations is achieved by orthogonally arranging the H-polarized coupling slot and the V-polarized coupling slot. The H-polarized feed and the V-polarized feed are located between the third dielectric layer and the fourth dielectric layer in the feed layer and are in the form of a strip line to couple and feed the two polarized coupling slots.

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

[0055] Since the feed point of the microstrip patch antenna unit is usually located at the edge of the microstrip antenna, the feed port of the S-band will affect the electrical performance of the L-band antenna at this time. Therefore, a feed conversion structure is needed to convert the S-band feed port to the center position of the microstrip antenna, reducing the influence of the S-band feed on the performance of the L-band antenna. The conversion structure is as shown in FIG. 2 (c). Figure 5

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

[0057] The L-band and the S-band are co-axial nested designs, and 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, the antenna needs to be isolated to enhance the signal isolation between the two bands and different polarizations. The structure of the isolated S-band dual-polarized antenna unit is as shown in FIG. 2 (a) and (b). Figure 6

[0058] ​​In order to improve the isolation between L-band and S-band antennas, a closed structure is formed by connecting the metal layer between the coupling layer and the ground plane together through the via at the edge of the S-band antenna module. Electromagnetic signals are only input through the feed point and output through the I-type slot coupling. Finally, the isolation of L-band signals is realized. At the same time, a via is used to increase an isolation wall between the coupling layer and the ground plane at the middle position of the S-band antenna module. The two polarized feed structures of the S-band are completely isolated to improve the isolation between the two polarizations. An additional ground layer is added between the I-type coupling feed layer and the stripline conversion layer as an isolation layer, which is vertically interconnected through the via to reduce the coupling in the internal conversion process of the S-band dual-polarized feed structure. In the conversion layer, the S-band feed adopts a closed design to completely isolate the feed 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 50 mm by optimizing the design 50 mm 12.3 mm, and the antenna structure is shown in Figure 6 (a)-(b).

[0060] 1.3, L-band and S-band nested co-axial design

[0061] The L-band and S-band nested co-axial antenna structure is shown in Figure 7 (a)-(b), one L-band antenna module and four S-band antenna modules are combined into a nested co-axial integrated dual-band dual-polarized antenna unit, and the spacing between the S-band antennas is 70 mm 70 mm. The L-band antenna adopts a microstrip dipole antenna and an S-band antenna module as a parasitic patch antenna form; the S-band adopts a microstrip patch antenna unit form with feed conversion design and isolation design.

[0062] In order to reduce the mutual influence between the L-band and S-band antennas, the S-band antenna module is located at the top of the L-band antenna, and the L-band cross microstrip dipole unit and the metal back cavity around it effectively isolate the single S-band antenna, effectively reducing the coupling between the S-band antennas. At the same time, the S-band can also be used as a parasitic patch for the L-band, so that the L-band and S-band have consistent phase center heights, ensuring the ability of the dual-band co-axial shared reflector.

[0063] The detailed parameters are shown in Figure 7 , wherein the height of the metal back cavity is 36.9 mm, the S-band antenna is located at 39.4 mm, the length of the L-band microstrip dipole antenna is 97 mm, the height of the S-band antenna is 12.3 mm, and the entire antenna size is 140 mm 140 mm 51.7 mm.

[0064] The L-band antenna uses paper honeycombs to secure and support the cross-microstrip dipole antenna. The S-band antenna's coupling layer and ground plane are designed using a microstrip circuit board. This integrated design effectively reduces the weight of the co-aperture nested L- and S-band antennas. This ensures the axial symmetry and common phase center height of the dual-band, dual-polarization antenna unit pattern, fulfilling the dual-band, dual-polarization, co-aperture, shared reflector requirements and ensuring the performance of the dual-band, dual-polarization reflector antenna. The shared reflector further contributes to the lightweight design of the antenna system, effectively reducing its weight.

[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 as follows 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 Figure 9 As shown in (a) and (b), the radiation patterns have good axial symmetry and good consistency between the two polarizations. At frequencies of 1.15 GHz, 1.25 GHz, 1.35 GHz, and 1.4 GHz, the H-plane and E-plane half-power beamwidths for H-polarization are (86°, 86°, 87°, and 85°) and (86°, 86°, 87°, and 85°), respectively. For V-polarization, the H-plane and E-plane half-power beamwidths 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 Figure 10 As given in (a), the isolation between the two polarization ports is as follows Figure 10 As shown in (b), it can be seen that the two polarizations are both 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 Figure 11As shown, the pattern has good axial symmetry, and the two polarizations have good consistency. At 3.05 GHz, 3.20 GHz and 3.35 GHz frequencies, the H-plane and E-plane half-power beamwidths of the H polarization are (73°, 70° and 68°) and (71°, 63° and 63°), respectively, and the H-plane and E-plane half-power beamwidths of the V polarization are (70°, 70° and 67°) and (69°, 63° and 64°), respectively, and the two polarizations have good consistency and symmetry.

[0072] 2.3, Dual-polarized shared reflector results;

[0073] The dual-frequency dual-polarized shared aperture antenna unit is used as a feed source of a reflector to form a dual-frequency dual-polarized reflector antenna. The reflector antenna pattern performance is shown in FIGS. 12-13.

[0074] FIG. 12(a) is a Phi=0 cross-section H polarization reflector antenna pattern result at different frequencies in the L band. As can be seen from the figure, the beamwidth and gain of the pattern at different frequencies are consistent, indicating that the phase center and beamwidth of the shared aperture antenna unit at different frequencies are consistent.

[0075] FIG. 12(b) is a Phi=0 cross-section V polarization reflector antenna pattern result at different frequencies in the L band. As can be seen from the figure, the beamwidth and gain of the pattern at different frequencies are consistent, indicating that the phase center and beamwidth of the shared aperture antenna unit at different frequencies are consistent.

[0076] FIG. 12(c) is a reflector antenna pattern result at different polarizations and different cross-sections at the center frequency in the L band. As can be seen from the figure, the beamwidth and gain of the pattern at the two polarizations and the two cross-sections are consistent, indicating that the shared aperture antenna unit has good axial symmetry of the pattern in the L band, and the two polarizations have consistent phase centers and beamwidths.

[0077] FIG. 13(a) is a Phi=0 cross-section H polarization reflector antenna pattern result at different frequencies in the S band. As can be seen from the figure, the beamwidth and gain of the pattern at different frequencies are consistent, indicating that the phase center and beamwidth of the shared aperture antenna unit at different frequencies are consistent.

[0078] FIG. 13(b) is a Phi=0 cross-section V polarization reflector antenna pattern result at different frequencies in the S band. As can be seen from the figure, the beamwidth and gain of the pattern at different frequencies are consistent, indicating that the phase center and beamwidth of the shared aperture antenna unit at different frequencies are consistent.

[0079] Fig. 13(c) is a reflection surface antenna pattern result of different polarizations and different sections at the center frequency of the S band. It can be seen from the figure that the beam width and gain of the patterns of two polarizations and two sections are consistent, which shows that the co-boresight antenna unit has quantized pattern axis symmetry at the S band and consistent phase centers and unit beam width of two polarizations.

[0080] From the simulation analysis results above, it can be seen that the dual-frequency dual-polarized co-boresight nested antenna unit can meet the electrical performance requirements of the reflector feed, and can realize the design requirements of the co-boresight, high integration, and light weight reflector feed. At the same time, the miniaturized size of the dual-frequency dual-polarized co-boresight nested unit can meet the design requirements of the phased array antenna.

[0081] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

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 evenly 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 single-polarization microstrip dipole antennas placed orthogonally. The orthogonal placement divides the antenna unit into four areas. The four S-band dual-polarization antenna modules are evenly distributed in the center of the four areas as parasitic units. 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 feed layer arranged sequentially 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. The two dielectric layers cross each other through the gap between the left radiation patch and the right radiation patch. 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 feed layer, a fourth dielectric layer, an isolation layer, a fifth dielectric layer, a feed conversion layer, a sixth dielectric layer, and a ground plane layer stacked in sequence from top to bottom, wherein the slot coupling feed is located in the feed layer.

2. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 1, characterized in that: The antenna unit further 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.

3. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 1, characterized in that: Paper honeycombs are used to fix and support the two cross-shaped single-polarization microstrip dipole antennas and the S-band antenna module.

4. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 1, 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.

5. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 4, characterized in that: The H polarization coupling slot and the V polarization coupling slot are placed orthogonally.

6. The small broadband dual-frequency dual-polarization nested co-aperture antenna unit according to claim 5, 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.

7. 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 to form a closed structure.

8. 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.

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 forms two completely closed feeding structures by using vias to connect H-polarized and V-polarized strip lines in the feeding conversion layer.

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