Common-aperture dual-polarization tight coupling array antenna capable of wide-angle scanning

Abstract

The invention belongs to the technical field of antennas, and relates to a common-caliber dual-polarization tight coupling array antenna capable of wide-angle scanning, which comprises a low-frequency antenna array surface, a low-frequency vertical branch knot, a low-frequency feed balun, a high-frequency antenna array surface, a low-frequency feed network and a coaxial connector. According to the invention, a traditional ultra-wideband tight coupling array antenna is decomposed into two antennas with small bandwidths, and loading of resistive materials is avoided through common-caliber configuration. Wherein an upper-layer low-frequency antenna unit is divided into a plurality of sub-units, electromagnetic transparency of a lower-layer high-frequency antenna is realized by adopting a winding line design, mutual interference of high and low frequencies is further inhibited by loading a vertical branch knot, and the fractal low-frequency sub-units are synthesized into a large unit through a power divider. According to the dual-polarization ultra-wideband antenna, the average efficiency reaches 85% in the working frequency bands of 2-6GHz and 7-18GHz, the active standing-wave ratio is smaller than 4 in the scanning range of + / -60 degrees, and the problem that in a traditional design, ultra-wideband, high efficiency, wide-angle scanning and dual polarization cannot be achieved at the same time is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna engineering, and relates to a common-aperture dual-polarized tightly coupled array antenna capable of wide-angle scanning, so as to meet the performance requirements of high efficiency, dual polarization and wide-angle scanning in the engineering application of ultra-wideband phased arrays. Background Art

[0002] With the rapid development of modern communication systems, higher requirements are put forward for phased array antennas with ultra-wideband, high efficiency and wide-angle scanning characteristics. By introducing a coupling structure between the antenna array elements, the tightly coupled dipole antenna array approximately forms a stable continuous current distribution on the array surface, so that the input impedance bandwidth of the antenna changes slowly with frequency. The introduction of capacitive coupling also cancels the inductive effect generated by the ground plane. Therefore, the tightly coupled antenna array naturally has broadband characteristics. Further, through the careful design of the dipole unit and the feeding structure, and the loading of the wide-angle matching layer, the ultra-wideband and wide-angle scanning of the tightly coupled array can be realized. In addition, compared with traditional broadband antennas such as Vivaldi, the tightly coupled array also has many advantages such as miniaturization, low profile and easy conformal.

[0003] In the process of further broadbanding the tightly coupled antenna, for the low-frequency end, due to the too low profile of the antenna, part of the energy is reflected by the ground plane and then canceled with another part, and cannot be normally radiated outward, which ultimately limits the bandwidth expansion at the low-frequency end; for the high-frequency end, when the antenna profile exceeds half a wavelength, a short-circuit resonance will be formed between the feeding balun and the ground plane, destroying the working performance of the antenna, which also limits its bandwidth expansion to the high-frequency end. To solve the above problems, the conventional solution is to introduce a resistive structure to absorb the unnecessary energy. For example, in the literature "A Ferrite-Loaded Ultralow Profile Ultrawideband Tightly Coupled Dipole Array", the author added a ferrite structure between the antenna and the ground plane to absorb the backward radiation, and finally achieved a 10-fold frequency bandwidth in the case of a low profile. And in the literature "Phased Array With Low-Angle Scanning and 46:1 Bandwidth", the author designed a multi-layer resistive frequency selective surface to absorb the common-mode resonance at multiple frequency points, and finally achieved an ultra-wide bandwidth of 46-fold frequency. However, while absorbing the useless energy, the above resistive materials will also absorb the normally radiated electromagnetic waves, resulting in a significant decrease in the antenna efficiency, and even causing a loss of more than 50% in some frequency bands, which has a great impact on the performance of the entire communication system.

[0004] In response to the contradiction between bandwidth and efficiency faced by the above-mentioned tightly coupled array, the paper "An Extremely Wideband Tightly Coupled Dipole Array With Shared-Aperture Configuration" proposed introducing the idea of ​​common aperture into the design of tightly coupled arrays. The authors arranged two tightly coupled arrays with smaller bandwidth under the same aperture plane, which can form an ultra-large bandwidth of 23.2 times the frequency after synthesis. Since no resistive material is required, the average efficiency of the array reaches 80%. However, due to the complex mutual coupling relationship between the arrays of the two frequency bands, the authors only achieved a maximum scanning angle of ±30° in the case of single polarization, which still has certain limitations in actual engineering.

[0005] Phased array antennas are an important part of satellite communications, electronic countermeasures, military radars and other key fields. There is always an urgent need for ultra-wideband, high efficiency, wide-angle scanning and multi-polarization. In the publicly available tightly coupled antenna designs, it is difficult to achieve the coexistence of ultra-wideband and high efficiency, or it is impossible to meet other important indicators such as wide-angle scanning. In view of this problem, the co-aperture dual-polarization tightly coupled array antenna with wide-angle scanning proposed in the present invention is of great significance. Summary of the invention

[0006] Based on the above background technology, the present invention aims at the deficiencies of the prior art and provides a co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning. The antenna consists of tightly coupled arrays of two frequency bands, and both are dual-polarized radiation. The low-frequency antenna is placed above the high-frequency antenna. After electromagnetic transparency treatment, the mutual coupling of the two frequency band antennas is reduced to ensure that the high and low frequency arrays can work normally at the same aperture. Under the premise of achieving high radiation efficiency, the low-frequency antenna is specially loaded to solve the problem that the existing co-aperture tightly coupled array cannot scan at a wide angle. Finally, the working frequency band of the antenna is 2GHz~6GHz, 7GHz~18GHz, that is, 9 times the bandwidth.

[0007] To achieve the above object, the present invention adopts the following solutions:

[0008] The present invention provides a co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning, wherein the co-aperture unit comprises from top to bottom a low-frequency antenna array face, a low-frequency vertical branch, a low-frequency feeding balun, a high-frequency antenna array face, a low-frequency feeding network, and a coaxial connector;

[0009] The low-frequency antenna array is composed of nine groups of dual-polarized low-frequency dipole sub-units. Six slots with different lengths are opened on both arms of the antenna unit to form a meandering structure. The dual-polarized low-frequency dipoles have exactly the same shape and are printed on both sides of a layer of Rogers 4003 dielectric substrate respectively, and the ends of the dipole arms are partially overlapped in the vertical direction. Square holes are opened on the substrate at the feeding point of each dipole to insert a low-frequency feeding balun; square holes are opened on the substrate at the third slot of each dipole arm to insert a low-frequency vertical stub.

[0010] The low-frequency vertical stub is a slender rectangular patch printed on a layer of Rogers 5880 dielectric substrate. After being inserted into the low-frequency antenna array, its upper end is connected to the low-frequency dipole arm.

[0011] The low-frequency feeding balun is a microstrip tapered balun printed on both sides of a Rogers 6002 dielectric substrate, and the metal part on the ground side is hollowed out.

[0012] The high-frequency antenna array is composed of nine groups of dual-polarized high-frequency dipoles and Marchand baluns. The dipoles and baluns are printed on one side of a layer of Rogers 6002 dielectric, and the inter-unit coupling patches and tapered feeders are printed on the other side. The dual-polarized antennas are arranged in a vertical grid layout, and the feeding end is extended to pass through the low-frequency feeding network to connect to a coaxial connector.

[0013] The low-frequency feeding network is composed of a three-layer metal structure and two layers of Rogers 5800 dielectric substrates. Among them, the upper and lower sides are dual-polarized one-to-nine Wilkinson power dividers. The output end of the power divider is connected to the feeding point of the low-frequency feeding balun, and the input end is connected to a coaxial connector after being vertically bent; the middle of the two substrates is the common ground of the entire common-aperture antenna. Corresponding openings are made in the low-frequency feeding network to allow the low-frequency feeding balun and the high-frequency antenna array to be inserted and passed through.

[0014] The one-to-nine Wilkinson power divider is composed of four cascaded one-to-three unequal Wilkinson power dividers. The power divider uses 100Ω patch resistors for isolation, and the performance of the dual-polarized power divider is the same.

[0015] Compared with the traditional tightly coupled array antenna, the present invention adopts a dual-frequency common-aperture configuration to synthesize an ultra-wideband, and innovatively decomposes a large-size low-frequency antenna unit into nine small units and connects them through a power divider to obtain better electromagnetic transparency performance. Furthermore, a low-frequency vertical stub is introduced to greatly suppress the mutual interference between the high-frequency and low-frequency antennas. Finally, on the premise of dual polarization of the array, without the need to introduce resistive materials, the average total efficiency of the antenna reaches 85% within a 9-fold frequency bandwidth, and it can meet the requirement that the scanning active standing wave is less than 4 within the range of ±60°. In addition, the profile height of the antenna is only 0.067 times the wavelength, belonging to a low-profile array antenna. Description of the Drawings

[0016] Figure 1It is a schematic diagram of the unit structure of the present invention in a periodic environment.

[0017] Figure 2 It is Figure 1 The front view of a small unit in the large unit of the low-frequency antenna in the shown antenna structure.

[0018] Figure 3 It is Figure 2 The left view of the shown antenna structure.

[0019] Figure 4 It is Figure 1 The front view of a high-frequency antenna unit in the shown antenna structure.

[0020] Figure 5 It is Figure 4 The right view of the shown antenna structure.

[0021] Figure 6 It is Figure 1 The front view of the low-frequency feeding network in the shown antenna structure.

[0022] Figure 7 It is Figure 6 The exploded view of the shown low-frequency feeding network.

[0023] Figure 8 It is Figure 1 The active VSWR diagram of the low-frequency band of the shown antenna structure.

[0024] Figure 9 It is Figure 1 The active VSWR diagram of the high-frequency band of the shown antenna structure

[0025] Figure 10 It is Figure 1 The total efficiency diagram of the shown antenna structure. Specific embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be specifically described in conjunction with the accompanying drawings in the embodiments of the present invention. The present invention includes, but is not limited to, the following specific working states of the antenna listed.

[0027] Refer to Figure 1 、Refer to Figure 2 、Refer to Figure 3 、Refer to Figure 4 、Refer to Figure 5 、Refer to Figure 6 、Refer to Figure 7 .

[0028] Such as Figure 1As shown, the present invention provides a unit structure of a co-aperture dual-polarized tightly coupled array antenna with wide-angle scanning in a periodic environment (the illustrated structure in the periodic environment, with the left and right sides and the front and back sides regarded as connected to each other), including a low-frequency antenna array surface 1, low-frequency vertical branches 2, a low-frequency feeding balun 3, a high-frequency antenna array surface 4, a low-frequency feeding network 5, and a coaxial connector 6. The low-frequency antenna unit is synthesized from 9 sub-units and adopts a fractal structure to obtain a better electromagnetic transparency effect. The low-frequency antenna array surface is horizontally placed directly above the aperture. The low-frequency vertical branches and the low-frequency feeding balun are connected to the low-frequency antenna array surface and are perpendicular to the low-frequency feeding network, where the output ends of the low-frequency feeding balun are respectively connected to the output ends of each feeding network. The high-frequency antenna array surface is in a vertical form. There are 9 independent dipoles for each polarization in the co-aperture unit. The dual-polarized high-frequency antennas are perpendicular and staggered with each other to form a grid form and are placed below the high-frequency antenna array surface. The feeding ends extend and pass through the low-frequency feeding network and then are connected to the coaxial ports. In actual engineering applications, the co-aperture array unit can be expanded into an array of any scale along the length and width directions.

[0029] The low-frequency antenna array surface is composed of 9 identical dual-polarized dipole sub-units as shown in Figure 2 . Each dipole arm is a meandering slotted structure. This method can extend the current path flowing on the antenna, thereby reducing the interference to the high-frequency end antenna. Among them, the horizontally polarized patch 1.1 and the vertically polarized patch 1.2 are respectively printed on the upper and lower sides of the low-frequency array substrate 1.3. The dual-polarized patches are centrosymmetric and overlap at the ends to form capacitive coupling.

[0030] The low-frequency vertical branch is a short strip-shaped metal patch 2.1, which is printed on the vertical branch substrate 2.2. The branch is inserted into the slot of each dipole arm (the third one starting from the feeding point outwards) and the metal parts are welded. The side of the branch with the patch printed faces the feeding point. In the co-aperture unit shown in Figure 1 , there should be 36 branches in total. Through the loading of the vertical branches, the mutual interference between the high and low frequencies of the co-aperture array during large-angle scanning can be further suppressed.

[0031] The low-frequency feeding balun is improved from a microstrip tapered balun. The balun floor 3.1 is an exponentially tapered line patch, and a hollowed-out form is adopted to improve the impedance matching. It is printed on one side of the low-frequency balun substrate 3.2, and the two ends are respectively welded to one arm of the low-frequency dipole and the floor. The feeding microstrip line is printed on the other side of the substrate 3.2. According to the need of connecting the low-frequency feeding, it is divided into a vertically polarized feeder 3.3 passing through the floor at the lower end and a horizontally polarized feeder 3.4 not passing through the floor. The upper ends of the two are welded to the other arm of the low-frequency dipole patch, and the lower ends are welded to the output ends of the corresponding low-frequency feeding network. In the co-aperture unit shown in Figure 1 , there should be 18 low-frequency feeding baluns in total.

[0032] The high-frequency antenna array is composed of a high-frequency dipole body 4.1 printed on one side of a high-frequency antenna substrate 4.3, a coupling patch 4.2 and a tapered feeder 4.4 printed on the other side. The feeding adopts a Marchand balun, and the tapered feeder realizes the change from 50Ω input impedance to the dipole. The dual-polarized antennas are completely identical except at the slotted positions of the coupling patches, and are staggered with each other in a 3×3 grid arrangement within the common aperture unit. The feeding end 4.5 of the high-frequency antenna array is extended to pass through the low-frequency feeding network and is welded to a coaxial connector 6.

[0033] The low-frequency feeding network from top to bottom is, in turn, an upper power divider 5.1, an upper dielectric substrate 5.4, a metal floor 5.3, a lower dielectric substrate 5.5, and a lower power divider 5.2. Both power dividers are one-to-nine equal power dividers formed by cascading four one-to-three unequal power dividers, and a total of 16 100Ω patch resistors 5.6 are used for port isolation. Except for some differences in the winding, the working performances of the two power dividers are the same. Among them, the input end 5.1.1 of the upper power divider is vertically bent and then passes through the two dielectric substrates and the metal floor to be welded to the coaxial connector, and the 9 output ends 5.1.2 are welded to the horizontally polarized feeder 3.4; the input end 5.2.1 of the lower power divider is directly bent and welded to the coaxial connector, and the 9 output ends are welded to the vertically polarized feeder 3.3. The 9 sub-units of the low-frequency antenna array are combined into a large unit through the power divider to reduce the number of coaxial connectors used. In actual manufacturing, the power divider and the floor are directly printed on the dielectric substrate, and the two substrates are bonded together. The low-frequency feeding balun and the high-frequency antenna array are both integrally inserted into the slots reserved on the upper dielectric substrate, and the balun floor 3.1 and the high-frequency dipole 4.1 are welded to the floor. Among them, the vertically polarized balun further passes through the gaps reserved on the floor and the lower substrate, so that the vertically polarized feeder 3.3 is welded to the output end of the lower power divider; the feeding end 4.5 of the high-frequency antenna array also further passes through the gaps reserved on the metal floor and the lower substrate and is welded to the coaxial connector.

[0034] The low-frequency array substrate 1.3 is a Rogers 4003 dielectric substrate, the vertical stub substrate 2.2 is a Rogers 5880 dielectric substrate, the low-frequency balun substrate 3.2 is a Rogers 6002 dielectric substrate, and the high-frequency antenna substrate 4.3, the upper dielectric substrate 5.4, and the lower dielectric substrate 5.5 are all Rogers 5880 dielectric substrates.

[0035] All the coaxial connectors have a 50Ω input impedance, and any feasible model can be adopted according to the actual manufacturing requirements.

[0036] Since the dual-polarized antennas in a wide-angle scanning common aperture dual-polarized tightly coupled array antenna proposed by the present invention are centrosymmetrically distributed, taking the horizontally polarized antenna as an example, Figure 1 the simulation results of the shown common aperture antenna unit in a periodic environment are given.

[0037] Figure 8 For Figure 1 the active voltage standing wave ratio (VSWR) of the antenna structure shown in the low frequency band (2 GHz - 6 GHz), it can be seen that when the maximum scan angle is 60°, the E-plane active VSWR is below 2.5 and the H-plane active VSWR is below 4.

[0038] Figure 9 For Figure 1 the active voltage standing wave ratio (VSWR) of the antenna structure shown in the high frequency band (7 GHz - 18 GHz), it can be seen that when the maximum scan angle is 60°, both the E-plane and H-plane active VSWRs are below 3.8

[0039] Figure 10 For Figure 1 the total efficiency diagram of the antenna structure shown, it can be seen that the average total efficiency of the antenna reaches 85% within the operating frequency band, and there is only a slight decrease near 7 GHz due to the proximity of the high and low frequency bands. Compared with the existing loaded resistive materials or simple co-aperture tightly coupled arrays, the present invention has the advantages of ultra-wideband, high efficiency, wide-angle scanning and dual polarization at the same time.

[0040] The above descriptions and embodiments are only some preferred examples of the present invention and do not constitute any limitation to the present invention. For professionals in the field, various changes and modifications can be made to this application, but the corrections and changes based on the idea of the present invention are still within the protection scope of the claims of the present invention.

Claims

1. A co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning, characterized in that: It includes a low-frequency antenna array, a low-frequency vertical branch, a low-frequency feeding balun, a high-frequency antenna array, a low-frequency feeding network, and a coaxial connector which are placed in sequence from top to bottom. The low-frequency antenna array includes a low-frequency array dielectric substrate, a low-frequency dipole unit, and a dual-polarization dipole unit, which are respectively printed on the upper and lower sides of the substrate and overlapped at the end of the dipole arm, and electromagnetic transparency is achieved by designing a slotted and meandering line for the dipole; the low-frequency vertical branch includes a metal short strip patch and a vertical branch dielectric substrate, and the electromagnetic transparency effect of the low-frequency antenna can be further improved by connecting the low-frequency vertical branch with the low-frequency dipole arm; the low-frequency feeding balun includes an exponential gradient balun floor, a microstrip feed line and a low-frequency balun substrate, wherein the gradient balun floor is hollowed out to tune the impedance matching; the high-frequency antenna array includes a high-frequency dipole body, a gradient Marchand balun, a coupling patch and a high-frequency antenna substrate, the gradient feed line realizes the change of 50Ω input impedance to the dipole, and the high-frequency dipole body and the gradient feed line plus the coupling patch are respectively printed on both sides of the high-frequency antenna substrate; The low-frequency feeding network comprises an upper power divider, an upper dielectric substrate, a metal floor, a lower dielectric substrate, and a lower power divider from top to bottom. Both power dividers are one-to-nine Wilkinson power dividers cascaded from four one-to-three unequal power dividers. The power dividers are printed on the upper and lower sides of the two dielectric substrates, respectively, and a metal floor is printed in the middle of the substrates and fits tightly.

2. The co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning according to claim 1, characterized in that: The low-frequency antenna array is a horizontal structure, which is composed of 9 dual-polarized low-frequency dipole small units, each of which is connected to a low-frequency vertical branch and a low-frequency feeding balun, and each dipole arm has 6 slots of unequal length; the low-frequency vertical branch is inserted into the third slot from the input end to the outside of each dipole arm, and one side of the patch is facing the input end, and a total of 36 vertical branches are required in the low-frequency antenna array unit; the low-frequency feeding balun is a vertical structure, inserted upward into each dipole port and connected to the port, and inserted downward into the low-frequency feeding network until the gradient index balun is connected to the floor, the upper end of the balun microstrip feeder is connected to one arm of the dipole, and the lower end is connected to the output port of the power divider, wherein the horizontal polarization feeder is directly connected to the upper power divider, and the vertical polarization feeder is extended and passes through the reserved gap of the low-frequency feeding network to be connected to the lower power divider.

3. The co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning according to claim 1, characterized in that: The high-frequency antenna array is a vertical structure, placed between the low-frequency antenna array and the low-frequency feeder network. The dual-polarized high-frequency antennas are staggered at the metal patch slots to form a grid structure. There are 9 independent high-frequency antennas under the common-aperture unit aperture surface. The dual-polarized high-frequency antenna units have completely identical structures except for the coupling patch. The high-frequency antenna body passes through the upper dielectric substrate of the low-frequency feed network and is connected to the metal floor. The feed port is further extended through the lower dielectric substrate to connect to the coaxial connector.

4. The co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning according to claim 1, characterized in that: The low-frequency feeding network is a horizontal structure, in which the upper and lower power dividers have the same performance except that the winding is slightly different. Each power divider requires 8 100Ω chip resistors. The output end of the upper power divider is connected to the horizontally polarized low-frequency feeding balun, and the input end is connected to the coaxial connector after passing through two layers of dielectric substrates through a vertical bending structure. The output end of the lower power divider is connected to the horizontally polarized low-frequency feeding balun, and the input end is connected to the coaxial connector through a vertical bending structure. The low-frequency feeding network needs to reserve a gap to allow the aforementioned structure to be inserted or passed through, and keep the metal parts unconnected.

5. The co-aperture dual-polarization tightly coupled array antenna capable of wide-angle scanning according to claim 1, characterized in that: The low-frequency array substrate is a Rogers 4003 dielectric substrate, the vertical branch substrate is a Rogers 5880 dielectric substrate, the low-frequency balun substrate is a Rogers 6002 dielectric substrate, the high-frequency antenna substrate, the upper dielectric substrate and the lower dielectric substrate are all Rogers 5880 dielectric substrates; the coaxial connectors all have a 50Ω input impedance and can adopt any feasible model according to actual manufacturing requirements.

Images