Dual-band dual-mode ultra-wideband co-aperture conformal antenna for unmanned aerial vehicle communication

Abstract

The application discloses a kind of dual-frequency dual-mode ultra-wideband common aperture conformal antenna for unmanned plane communication, belongs to conformal array antenna technical field, including the fuselage conformal array antenna and wing conformal array antenna by same radiating element;Dual-frequency dual-mode common aperture ultra-wideband radiating element in fuselage conformal array antenna is set with closed surface configuration around fuselage, dual-frequency dual-mode common aperture ultra-wideband radiating element in wing conformal array antenna is set with open surface configuration along wing extension;The fuselage conformal array antenna and the wing conformal array antenna cooperate to provide omnidirectional beam coverage and directional beam switching capability.The application can simultaneously provide omnidirectional beam coverage and directional beam switching function, realize wide-angle domain beam scanning in dipole operating mode, and realize forward / backward beam switching and multiple linear polarization switching by switching subarray in Vivaldi operating mode.

Description

Technical Field

[0001] This invention belongs to the field of ultra-wideband dual-band dual-mode common aperture conformal array antenna technology, and particularly relates to a dual-band dual-mode ultra-wideband common aperture conformal antenna for UAV communication. Background Technology

[0002] In emergency rescue missions (such as earthquakes and fires), a reliable emergency communication network is crucial for controlling the disaster and rescuing trapped personnel. Unmanned aerial vehicles (UAVs), with their superior maneuverability, are an ideal vehicle for constructing temporary emergency communication networks. For example, in mountainous forest fire rescue scenarios, to improve the efficiency of rescuing trapped personnel, UAV swarms can be used as aerial base stations to build a high-capacity, high-quality, and long-distance air-to-ground / air-to-air communication network. Air-to-ground communication enables communication between trapped personnel on the ground and search and rescue personnel. Air-to-air communication supports collaborative communication within the UAV swarm and relays information to a remote emergency management center via multi-hop networking.

[0003] To meet the above air-to-ground / air-to-air communication requirements, the antenna mounted on the UAV needs to support two key operating modes and their corresponding radiation characteristics: side-firing mode and end-firing mode. Side-firing mode (UAV circumferential radiation → air-to-ground communication): The antenna's main energy is radiated along the circumference of the UAV fuselage, serving the communication link between the UAV and ground personnel. In this mode, due to severe obstruction from ground vegetation and obstacles, the antenna needs to operate in the low-frequency band with a longer wavelength, utilizing the stronger diffraction capability of low-frequency electromagnetic waves to ensure the reliability and penetration (or coverage) of the communication link. End-firing mode (UAV flight direction radiation → air-to-air communication): The antenna's main energy is radiated along the flight direction of the UAV, serving (1) collaborative communication between UAVs and (2) remote networking communication between UAV swarms and the emergency management center. Compared to the ground environment, the air communication environment is relatively open and has fewer obstructions. Therefore, this mode can operate in a higher frequency band to utilize the wider potential bandwidth resources of the high-frequency band, thereby supporting higher transmission rates and greater communication capacity. Furthermore, the frequent attitude changes of UAVs during missions can easily lead to polarization mismatch in inter-UAV communication links. Therefore, the ability of antennas to flexibly switch or support multiple polarization modes is crucial. Finally, given the stringent size, power consumption, and aerodynamic requirements of UAV platforms, a common-aperture, conformal array antenna design offers significant advantages: while reducing additional load and air resistance (significantly mitigating aerodynamic impacts), it significantly improves antenna radiation efficiency and gain within a limited space (enhancing space utilization efficiency), which directly affects the quality, stability, and effective coverage distance of the communication link (increasing communication range). In summary, to efficiently support the high-reliability air-to-ground, high-capacity air-to-air coordination, and long-range relay capabilities required by UAV swarms in emergency communication scenarios, designing a high-performance antenna integrating dual-band (low-frequency air-to-ground target, high-frequency air-to-air target), dual-radiation modes (side-firing, end-firing), multi-polarization compatibility, and employing a common-aperture, conformal array structure is a key step in achieving the aforementioned objectives.

[0004] Dual-band, common-aperture antennas with both directional and omnidirectional radiation modes offer a potential solution for addressing the simultaneous ground-to-air and air-to-ground communication needs of unmanned aerial vehicles (UAVs). Broadband characteristics are crucial for achieving high-speed, high-capacity data transmission. However, existing dual-band, dual-mode antennas either have narrowband designs in both frequency bands or only achieve broadband coverage in a single band. Therefore, these designs cannot simultaneously meet the broadband communication requirements in both frequency bands. While research exists on antennas with broadband characteristics in both frequency bands, their planar structure limits their direct application on UAV platforms. Furthermore, some flexible dual-band, dual-mode antennas developed for wireless body area network (VBA) applications may be compatible through conformal design. However, these antennas primarily operate in unit cell form and generally suffer from insufficient gain.

[0005] In conclusion, designing an antenna that can be practically applied to UAVs, supports dual-band dual-mode, has broadband characteristics, and adopts a common-aperture conformal array architecture still faces significant challenges. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a dual-frequency, dual-mode, ultra-wideband, common-aperture conformal antenna for UAV communication, thereby resolving the issues present in the prior art.

[0007] To achieve the above objectives, the present invention provides a dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication, comprising: a fuselage conformal array antenna and a wing conformal array antenna;

[0008] Both the fuselage conformal array antenna and the wing conformal array antenna are composed of multiple identical dual-frequency dual-mode common-aperture ultra-wideband radiating elements.

[0009] The dual-band dual-mode common-aperture ultra-wideband radiating element in the fuselage conformal array antenna is configured with a closed curved surface surrounding the fuselage, while the dual-band dual-mode common-aperture ultra-wideband radiating element in the wing conformal array antenna is configured with an open curved surface extending along the wing. The fuselage conformal array antenna and the wing conformal array antenna work together to provide omnidirectional beam coverage and directional beam switching capability.

[0010] Optionally, the dual-frequency dual-mode common-aperture ultra-wideband radiating element includes a rectangular dielectric substrate, a broadband dipole antenna, and two Vivaldi subarrays.

[0011] The broadband dipole antenna includes a first rectangular radiating patch and a second rectangular radiating patch printed on the upper and lower surfaces of the rectangular dielectric substrate, respectively; two Vivaldi subarrays are integrated on the first and second rectangular radiating patches, respectively; wherein, the broadband dipole antenna is used to support a broadband omnidirectional radiation mode in the low-frequency band, and the two Vivaldi subarrays are used to support a broadband directional end-fire radiation mode in the high-frequency band.

[0012] Optionally, the first rectangular radiating patch and the second rectangular radiating patch are parallel to each other in the thickness direction of the rectangular dielectric substrate, with a spacing of 8 mm and a length of 70 mm.

[0013] Optionally, the broadband dipole antenna further includes an unbalanced feeding structure, which includes a microstrip line printed on the upper surface of the dielectric substrate. One end of the microstrip line is connected to the middle of the first rectangular radiating patch, bends at a predetermined length, and extends to the edge of the dielectric substrate, together with the second rectangular radiating patch, to form the unbalanced feeding structure of the dipole antenna.

[0014] Optionally, each Vivaldi subarray includes two exponentially tapered slots etched on corresponding rectangular radiating patches and a common circular resonant cavity; the narrow end of each exponentially tapered slot is connected to the common circular resonant cavity after passing through an elliptical slit and a rectangular slit in sequence.

[0015] Optionally, the Vivaldi subarray also includes a feed structure, which includes:

[0016] A gradient microstrip line printed on a corresponding rectangular radiating patch has one end electromagnetically coupled to the common circular resonant cavity;

[0017] A fan-shaped parasitic structure connected to the other end of the tapered microstrip line is used to achieve impedance matching;

[0018] In this method, forward end-fired beams or backward end-fired beams can be achieved by selectively feeding the tapered microstrip line.

[0019] Optionally, the conformal array antenna of the fuselage includes a cylindrical conformal subarray composed of four dual-frequency dual-mode common-aperture ultra-wideband radiating elements; wherein each dual-frequency dual-mode common-aperture ultra-wideband radiating element is bent along the short side direction, and the four bent radiating elements are arranged at equal angular intervals around the central axis of the conformal cylindrical surface.

[0020] Optionally, the conformal array antenna of the fuselage includes three cylindrical conformal sub-arrays, which are arranged by rotating -90°, 45° and 135° around the central axis, respectively.

[0021] Optionally, the wing conformal array antenna includes a wing conformal subarray composed of four radiating elements, wherein each dual-frequency dual-mode common-aperture ultra-wideband radiating element is bent along the long side, and the four bent radiating elements are arranged in a straight line along the leading edge of the UAV wing.

[0022] Optionally, the three cylindrical conformal subarrays of the fuselage conformal array antenna work together with the wing conformal subarray of the wing conformal array antenna to form a UAV conformal antenna array, providing omnidirectional beam coverage and directional beam switching capabilities.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] This invention provides a dual-band, dual-mode, common-aperture ultra-wideband conformal antenna array for UAV communication. Compared with conventional common-aperture antennas, it offers advantages such as large bandwidth, wide coverage, dual modes, and multi-polarization. The antenna element used in this invention integrates two ultra-wideband antennas operating in different modes onto a single structure, maintaining ultra-wideband coverage while satisfying both side-fire and end-fire functions, thus offering multi-functional advantages. This invention uses two exponentially conical slots etched on each dipole arm to form a Vivaldi subarray, which not only improves the antenna gain in Vivaldi mode but also reduces the sidelobes of the high-frequency mode antenna when arrayed with a common-aperture antenna. The design of connecting the tails of the two Vivaldi slots on the dipole arm through slots, sharing a circular resonant cavity and a feed port, not only reduces the complexity of the antenna feed structure but also reduces the number of feed ports. This reduces costs while avoiding interference from complex feed networks to the dipole mode. This invention employs a method of jointly assembling three conformal arrays for the fuselage and one conformal array for the wing. While maintaining high conformal gain, it achieves a maximum beam coverage of 360° × 76° in dipole mode. In Vivaldi mode, it allows for switching between forward and backward beams, as well as switching between horizontal, vertical, and 45° and -45° linear polarization. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0026] Figure 1 This is a schematic diagram of a conformal array of dual-frequency dual-mode common-aperture ultra-wideband antenna elements according to an embodiment of the present invention;

[0027] Figure 2 The following is a structural diagram of a dual-frequency, dual-mode, common-aperture ultra-wideband antenna element according to an embodiment of the present invention; (a) is a three-dimensional diagram of the antenna element; (b) is a planar diagram of the antenna element.

[0028] Figure 3 The following diagrams represent the simulated and measured reflection coefficients and port coupling coefficients of a dual-frequency, dual-mode, common-aperture ultra-wideband antenna element according to an embodiment of the present invention: (a) simulated and measured reflection coefficients in dipole mode; (b) simulated and measured reflection coefficients in Vivaldi mode; (c) simulated and measured coupling coefficients in dipole mode; and (d) simulated and measured coupling coefficients in Vivaldi mode.

[0029] Figure 4 The following are simulation and measured gain diagrams of the antenna element in an embodiment of the present invention: (a) shows the antenna gain as a function of frequency in dipole mode; (b) shows the antenna gain as a function of frequency in Vivaldi mode.

[0030] Figure 5 This is a simulation radiation pattern of the antenna element in an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the conformal array and beam combination of dual-frequency dual-mode common-aperture ultra-wideband antenna elements according to an embodiment of the present invention;

[0032] Figure 7 The following are simulation and testing active reflection coefficients of elements in the conformal subarrays of the fuselage and wing according to embodiments of the present invention: (a) Active reflection coefficient of elements in the conformal subarray of the fuselage in dipole mode; (b) Active reflection coefficient of elements in the conformal subarray of the fuselage in Vivaldi mode; (c) Active reflection coefficient of elements in the conformal subarray of the fuselage in dipole mode; (d) Active reflection coefficient of elements in the conformal subarray of the wing in Vivaldi mode.

[0033] Figure 8 The active reflection coefficients of the conformal subarray of fuselage and wing are simulated and measured; (a) is the active reflection coefficient of the conformal subarray of fuselage and wing in dipole mode; (b) is the active reflection coefficient of the conformal subarray of fuselage and wing in Vivaldi mode.

[0034] Figure 9 The following are simulation and measured mutual coupling curves of the fuselage conformal antenna array ports according to an embodiment of the present invention: (a) Simulation and measured mutual coupling curves of the four ports in the fuselage conformal array dipole mode; (b) Simulation and measured mutual coupling curves of the four ports in the fuselage conformal array Vivaldi mode; (c) Simulation and measured mutual coupling curves of the four ports in the wing conformal array dipole mode; and (d) Simulation and measured mutual coupling curves of the four ports in the wing conformal array Vivaldi mode.

[0035] Figure 10 The following are simulation and measured gain diagrams of the conformal array of the fuselage according to an embodiment of the present invention: (a) gain diagram of the fuselage in dipole mode; (b) gain diagram of the fuselage in Vivaldi mode; (c) gain diagram of the wing in dipole mode; and (d) gain diagram of the wing in Vivaldi mode.

[0036] Figure 11 The above are simulation and measured radiation patterns of the conformal array of the fuselage according to an embodiment of the present invention.

[0037] Figure 12 The simulation and measured radiation patterns of the conformal wing array at different frequencies are shown in the embodiments of the present invention. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0040] Example 1

[0041] like Figure 1 As shown, this embodiment provides a dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication, including a dual-band dual-mode common-aperture ultra-wideband radiating element, a dual-band dual-mode common-aperture ultra-wideband conformal array antenna based on the UAV fuselage, and a dual-band dual-mode common-aperture ultra-wideband conformal array antenna based on the UAV wing. The dual-band dual-mode common-aperture ultra-wideband radiating element, the dual-band dual-mode common-aperture ultra-wideband conformal array antenna based on the UAV fuselage, and the dual-band dual-mode common-aperture ultra-wideband conformal array antenna based on the UAV wing are all combined using a design method, which includes:

[0042] Step S1: Design a dual-frequency, dual-mode, common-aperture ultra-wideband radiating element, such as... Figure 2 As shown, the specific steps include the following:

[0043] Step S1.1: On a piece with length and width L s and W s A broadband dipole radiation structure is first printed on the top and bottom surfaces of a rectangular dielectric substrate. The substrate used is model F4BM220 with a thickness of H. s The radiating structure of the dipole consists of a first rectangular radiating patch printed on the top surface of the substrate and a second rectangular radiating patch printed on the bottom surface of the substrate, with a distance W between the rectangular patches. g Both rectangular radial structures have a length of L. p The width is the same as the width of the dielectric substrate. All rectangular patches are 1-ounce thick copper films.

[0044] Wherein, substrate length L s and width W s The diameters are 210mm and 60mm respectively; the distance between the two arms of the dipole is W. g It is 8mm long and the length is l s It is 70mm.

[0045] An unbalanced-fed dipole antenna is printed on a rectangular dielectric substrate made of F4BM220, with the two arms of the dipole antenna located on the upper and lower sides of the substrate, respectively.

[0046] Step S1.2: Connect a wire of width W to the middle part of the first rectangular radiating patch. f The microstrip line has a length of L. f1 The bend extends to the edge of the substrate and forms an unbalanced feed structure for the dipole antenna with the second rectangular radiating patch. Port 1 is the feed port for dipole mode. Wherein, W... f 3mm; L f1 The thickness is 10mm. The purpose of using unbalanced feeding in dipole mode is to eliminate the need for an additional balun, allowing direct connection to the interface via coaxial cable, thus reducing the complexity of the antenna's feeding structure.

[0047] The feeding structure of the dipole is formed by connecting a microstrip line in the middle of the upper dipole arm, which is then bent and extended to the other dipole arm at the edge and bottom.

[0048] Step S1.3: Two exponential conical slots are etched on both rectangular radiating patches to form a Vivaldi subarray. The ends of the conical slots are connected to the circular resonant cavity after being merged through slots. The two exponential conical slots improve the gain of the Vivaldi antenna. On the other hand, compared with the single-arm single-slot scheme, the double-arm double-slot design significantly suppresses the sidelobe level degradation caused by the excessive spacing between high-frequency Vivaldi elements when using a common aperture array.

[0049] The width W of the front opening of the conical groove s1 It is 20.67mm, and the rear width W s2 It is 0.4mm, and the length is L. s The length is 40mm; the major axis R of the elliptical slit connected to the end of the rectangular groove is... l1 and short axis R s1 The lengths Ld and Wd of the rectangular slit connected to the elliptical slit are 16mm and 7.5mm respectively; the length Ld and width Wd of the rectangular slit are 10mm and 0.47mm respectively, and the radius D of the circular resonant cavity is... c It is 8mm.

[0050] Two tapered slots are etched on each of the two rectangular dipole arms to form a Vivaldi subarray. The slots are determined by an exponential function, integrating the omnidirectional mode of the dipole and the end-fire mode of the Vivaldi antenna onto a single antenna. The narrow ends of the tapered slots forming the Vivaldi subarray on each arm are connected in parallel via an elliptical arc-shaped gap and then connected to a circular resonant cavity via a rectangular gap, greatly reducing the number of ports and the complexity of the subsequent feeding structure.

[0051] Step S1.4: A gradient microstrip line is printed on the other side of each rectangular radiating patch to form the Vivaldi array feed line. A fan-shaped parasitic structure is connected to the end of the gradient microstrip line to achieve impedance matching. The complexity of the feed structure of the Vivaldi subarray on each arm is greatly reduced, improving the efficiency of the antenna system and reducing the mutual interference between the two modes. Ports 2 and 3 are the feed ports of the Vivaldi subarray.

[0052] The width W of the gradient microstrip line v1 and narrow end width W v2 The diameters are 0.67 mm and 4.6 mm respectively, with a length Lv of 30 mm; the arc θ of the fan-shaped parasitic structure s and radius R s The angles are 86° and 5.9 mm, respectively.

[0053] Each Vivaldi subarray on each arm is fed by only one tapered microstrip line. This feeding structure is located on the other side of the rectangular slot in each arm and can be switched between forward end-fire and backward end-fire modes via port switching.

[0054] Figure 3 The simulation and experimental results of the designed dual-frequency, dual-mode, common-aperture ultra-wideband radiating element are presented in two operating modes, including reflection coefficient, port isolation, and realized gain. Figure 3 As shown in (a), the -10dB impedance bandwidth measured in dipole mode is 88.9% (0.8-2.08GHz), which is slightly narrower than the simulated bandwidth of 94.7% (0.75-2.1GHz). Figure 3 (b) shows that in the Vivaldi mode, the measured overlap impedance bandwidth of port 2 and port 3 reaches 99.8% (2.21-6.61 GHz), which is better than the simulated bandwidth of 93.6% (2.3-6.35 GHz). Figure 3 (c) and (d) in the diagram show that, in both dipole and Vivaldi modes, the measured and simulated port isolation is better than -15 dB over the entire operating bandwidth. Figure 4 The measured and simulated gain values ​​for two modes are given: Figure 4 As shown in (a), in dipole mode, the measured gain is 1.57-5.15 dBi within the operating bandwidth, and the simulated value (1.86-5.82 dBi) is close to the measured result; Figure 4 As shown in (b), the measured gain in Vivaldi mode is 4.01–8.22 dBi, slightly lower than the simulated value of 4.53–8.9 dBi. Overall, the measured results agree well with the simulation results.

[0055] Figure 5The simulated and measured radiation patterns of the designed dual-frequency, dual-mode, common-aperture ultra-wideband radiating element in the xz and yz planes are presented in dipole and Vivaldi modes. Figure 5 As shown in (a), (c), and (e), when the dipole mode is operating, the xz plane (E plane) at frequencies of 0.9 GHz, 1.3 GHz, and 1.7 GHz exhibits a typical figure-eight pattern: the measured half-power beamwidth (HPBW) is 79°, 70°, and 63°, respectively, and the corresponding simulated values ​​are 78°, 68°, and 60°. Figure 5 (b), (d), and (f) in the data show that the yz plane (H plane) exhibits quasi-omnidirectional radiation: the measured roundness errors are 2.62dB, 1.6dB, and 3.1dB, respectively, while the simulated values ​​are 0.76dB, 1.84dB, and 2.88dB. The power fluctuation across the entire frequency band remains within ±1.5dB, and the cross-polarization level is always better than -15dB.

[0056] When working in Vivaldi mode Figure 5 The values ​​(g), (i), and (k) in the figure show that the measured HPBW of the xz plane radiation pattern at the 2.5 / 4.5 / 6 GHz frequencies are 117°, 84°, and 60°, respectively, and the corresponding simulated values ​​are 120°, 88°, and 64°. Figure 5 In the (h), (j), and (l) diagrams, the measured HPBW in the xy plane is 58°, 54°, and 43°, respectively, corresponding to the simulated values ​​of 60°, 54°, and 42°. The measured front-to-back ratio (FBR) is better than 10.83dB across the entire frequency band, showing a high degree of agreement with the simulation. The measured cross-polarization level is better than -17.8dB, approximately 5.2dB higher than the simulated value of -23dB. The measured and simulated radiation patterns of both operating modes show good consistency across the entire operating bandwidth, successfully verifying the design effectiveness of the dual-mode operating mechanism.

[0057] Step S2: Based on the aforementioned dual-band dual-mode common-aperture ultra-wideband radiating element, design a fuselage-conformal dual-band dual-mode common-aperture ultra-wideband array antenna. By controlling the control unit spacing, achieve two different operating modes in the two ultra-wideband frequency bands. Specifically, this includes the following steps:

[0058] Step S2.1: Bend the proposed dual-frequency dual-mode common-aperture ultra-wideband radiating element along the short side direction, with a curvature of r, where the curvature r is 3.34;

[0059] Step S2.2: Rotate the conformal elements periodically by 14° around the center of the conformal cylinder to form a 1×4 conformal subarray for the fuselage;

[0060] Step S2.3: Design a cylindrical model similar to the drone fuselage using ABS material, with a radius of 300mm.

[0061] Step S2.4: Place a 1×4 conformal subarray of the fuselage on the model to form a UAV fuselage subarray;

[0062] Step S2.5: As Figure 6 As shown, a 1×4 conformal fuselage subarray is rotated θ1, θ2 and θ3 along the cylindrical X-axis to form three 1×4 conformal fuselage subarrays, namely subarray 1, subarray 2 and subarray 3; where θ1, θ2 and θ3 are -90°, 45° and 135° respectively. Figure 6 (a) is a schematic diagram of the conformal array antenna pattern of the fuselage and wing in dipole mode; Figure 6 (b) is a schematic diagram of the conformal array antenna pattern of the fuselage and wing in Vivaldi mode; Figure 6 (c) Schematic diagrams of two types of subarrays and beam combinations.

[0063] The conformal subarray of the fuselage assembled in step S2.2 operates in a mode where each antenna element is fed with equal amplitude and in phase, and the radiation direction of the array includes two main beams, one above and one below.

[0064] The conformal array of the fuselage assembled in step S2.5 can achieve beam switching in multiple directions when operating in dipole mode, and can switch the front and rear beams and change the polarization by switching different subarrays when operating in Vivaldi mode.

[0065] Step S3: Based on the aforementioned dual-frequency dual-mode common-aperture ultra-wideband radiating element, design a wing-conformal dual-frequency dual-mode common-aperture ultra-wideband array antenna. Specifically, this includes the following steps:

[0066] Step S3.1: Bend the proposed dual-frequency dual-mode common-aperture ultra-wideband radiating element along its long side to conform to the designed wing.

[0067] Step S3.2: Form a 1×4 wing conformal subarray along the lateral direction of the wing, which, together with the three fuselage conformal subarrays, forms the UAV conformal array. In dipole mode, this antenna system can achieve a maximum beam coverage of 360°×76°. In Vivaldi mode, it can switch between forward and backward beams and between horizontal, vertical, 45°, and -45° linear polarization.

[0068] The conformal subarray of the wing formed in this step is formed by bending the proposed unit conformally along another dimension, which is different from the bending direction of the conformal unit of the fuselage.

[0069] The conformal subarray of the wing, assembled in step S3.2, together with the conformal subarray of the fuselage, forms a conformal array system for the UAV. In dipole mode, this system can achieve a maximum beam coverage of 360° × 76°. In Vivaldi mode, it can switch between forward and backward beams and between horizontal, vertical, 45°, and -45° linear polarization.

[0070] Figure 7 The reflection coefficients of the radiating elements in the proposed conformal arrays for the fuselage and wings are shown under two operating modes. As shown in the figure, in dipole mode, the measured -10dB impedance bandwidth of the central radiating element in both arrays is narrower than that of the edge elements. Specifically, as... Figure 7 As shown in (a) and (c), the center elements of the conformal arrays for the fuselage and wings achieve -10 dB relative bandwidths of 78.2% (0.795-1.815 GHz) and 74.5% (0.885-1.935 GHz), respectively; while the simulation results are 73.1% (0.825-1.755 GHz) and 69.7% (0.87-1.8 GHz), respectively, which are narrower than the measured results. In contrast, the edge elements of the two conformal arrays achieve significantly wider relative bandwidths of 86% (0.735-1.845 GHz) and 94% (0.72-1.995 GHz), respectively, with simulated values ​​of 88.4% (0.72-1.86 GHz) and 89.6% (0.7-1.92 GHz), which are close to the measured results. In the Vivaldi array configuration, Figure 7 Images (b) and (d) show that the impedance bandwidth of the edge elements and the center elements is almost the same. Actual measurements show that: Figure 7 (b) shows that the -10dB overlap bandwidth of the edge and center units in the conformal array of the fuselage is 89.4% (2.4-6.28GHz), while the simulation result is 93.2% (2.35-6.45GHz). Figure 7 (d) shows that the measured overlap bandwidth of elements at different positions in the conformal wing-body array reaches 91.8% (2.34-6.42 GHz), while the corresponding simulation result is 89.5% (2.5-6.55 GHz). This demonstrates a high degree of agreement between the simulation and experimental results. Furthermore, the reflection coefficients of each array were measured under two operating modes. Since the power divider was purchased from the manufacturer and no simulation data was provided, only the measured reflection coefficients of the overall conformal subarray system were obtained and plotted. Figure 8 As shown in (a), in dipole mode, the conformal arrays of the wing and fuselage achieve an ultrawide -10dB impedance bandwidth of 110% (0.63–2.17 GHz) and 105% (0.65–2.09 GHz), respectively. Figure 8(b) shows that the measured bandwidths in Vivaldi mode are 105% (2.09–6.75 GHz) and 99.4% (2.03–6.65 GHz), respectively. Ultimately, it was found that the measured impedance bandwidths of the two conformal subarrays are much wider than those of the conformal radiating element, which may be due to the insertion loss of the power divider network.

[0071] Figure 9 The simulation and measured coupling results between radiating elements in two conformal arrays (fuse conformal and wing conformal) are presented. Figure 9 As shown in (a) and (c), in dipole mode, the measured and simulated mutual coupling levels gradually decrease with increasing element spacing and frequency. Within the operating frequency band, the peak measured mutual coupling coefficient in the low-frequency region is approximately -8 dB, primarily attributed to the enhanced near-field mutual coupling effect due to electrical size reduction. Furthermore, Figure 9 (b) and (d) in the figure show that the Vivaldi cells in the two conformal arrays maintain a mutual coupling level of less than -20dB in the operating frequency band, demonstrating superior port isolation performance. Figure 10 The simulation and measured gains of conformal arrays for fuselage and conformal arrays for wings were compared under two operating modes. Figure 10 (a) shows that for the conformal array of the fuselage operating in dipole mode, the measured realized gain varies from 4.1 dBi to 9.06 dBi within its operating bandwidth, which is slightly lower than the simulated range of 4.8 dBi to 9.53 dBi. Figure 10 (b) shows that in Vivaldi mode, the measured gain range is 9.39–14.23 dBi, while the simulation results are 10.16–14.66 dBi. For conformal wing arrays, the results are as follows... Figure 10 As shown in (c), the measured gain in dipole mode is 3.4-8.75 dBi in the operating frequency band, which is in high agreement with the simulated gain of 4.5-9.18 dBi. Figure 10 (d) shows that the measured gain range of the array in Vivaldi mode is 9.96-14.53 dBi, and the simulation result is 10.71-14.93 dBi.

[0072] Figure 11 The simulated and measured normalized radiation patterns of the conformal array antenna on the fuselage in two principal planes under two operating modes are shown. Figure 11As shown in (a), (b), (c), (d), (e), and (f), in dipole mode, the measured half-power beamwidth (HPBW) in the xz plane is 76°, 72°, and 64° at 0.9 GHz, 1.3 GHz, and 1.7 GHz, respectively, while the corresponding values ​​in the yz plane are 54°, 46°, and 36°. The cross-polarization levels within the HPBW at the three frequencies are below -14.6 dB, -27.8 dB, and -24.3 dB, respectively. Results for the Vivaldi array mode are as follows... Figure 11 As shown in (g), (h), (i), (j), (k), and (l), the measured HPBW in the xz plane is approximately 100°, 74°, and 38° at 2.5 GHz, 4.5 GHz, and 6 GHz, respectively, while the measured HPBW in the xy plane is approximately 20°, 12°, and 8°, respectively. The peak sidelobe levels measured in the xy plane are correspondingly lower than -16 dBi, -10 dBi, and -9 dBi. Furthermore, across the entire Vivaldi mode band, the measured cross-polarization level and front-to-back ratio (FBR) in the HPBW region are both better than -10 dB. The measured radiation pattern of the conformal fuselage array agrees well with the simulation results. For the conformal wing array, Figure 12 The normalized radiation patterns of the two principal planes are shown in two modes. For example... Figure 12 As shown in (a), (b), (c), (d), (e), and (f), in dipole mode, the measured HPBW in the xz plane is 76°, 72°, and 64° at 0.9 GHz, 1.3 GHz, and 1.7 GHz, respectively, while the corresponding values ​​in the yz plane are 54°, 46°, and 36°. The cross-polarization suppression within the HPBW at all three frequencies is better than -18 dB, -29 dB, and -24 dB. Figure 12 As shown in (g), (h), (i), (j), (k), and (l), in Vivaldi mode, the measured HPBW in the xz plane reaches 100°, 74°, and 45° at 2.5 GHz, 4.5 GHz, and 6 GHz, respectively; the xy plane beam is significantly narrowed, with measured HPBWs of 18°, 12°, and 8°, corresponding to peak sidelobe levels of -15 dBi, -11 dBi, and -8 dBi. Notably, in this mode, the measured cross-polarization suppression is better than -14 dB, -15 dB, and -10.8 dB at the three frequency points, respectively, and the front-to-back ratio (FBR) is better than -14 dB, -16 dB, and -10.3 dB, respectively. The simulation and measurement results for the conformal wing array are also highly consistent.

[0073] This invention first designs a broadband patch dipole antenna element with unbalanced feeding to support omnidirectional broadband communication in the low-frequency band. Secondly, Vivaldi slots are etched on the two arms of the dipole to achieve a directional broadband communication mode with switchable forward / backward radiation patterns in the high-frequency band. The two Vivaldi slots etched on each dipole arm not only improve the antenna gain in Vivaldi mode but also effectively avoid the problem of increased sidelobe levels caused by excessive spacing between Vivaldi antennas in the high-frequency band when assembling common-aperture elements. Furthermore, the parallel feeding method combining microstrip line coupling and slot shunting significantly reduces the number of feed ports and lowers system complexity. Based on the proposed broadband common-aperture element and considering the UAV's shape characteristics, two array configurations are designed to enhance gain and enrich the polarization modes of directional radiation: a fuselage conformal array and a wing conformal array. The fuselage conformal array consists of three 1×4 subarrays arranged parallel to each other along the circumference. The Vivaldi array antennas (distributed in subarrays 1, 2, and 3) operate in vertical, 45° slant, and -45° slant polarization modes, respectively, while the dipole array antennas operate in a horizontal polarization mode parallel to the fuselage direction. The wing conformal array is a 1×4 subarray arranged parallel to the wing's leading edge. Its Vivaldi array antennas provide horizontal polarization, and the dipole array antennas operate in the same mode as the fuselage array, also with horizontal polarization parallel to the fuselage direction.

[0074] This invention provides a dual-band, dual-mode, common-aperture ultra-wideband conformal antenna array for UAV communication. Compared with conventional common-aperture antennas, it offers advantages such as large bandwidth, wide coverage, dual modes, and multi-polarization. The antenna element used in this invention integrates two ultra-wideband antennas operating in different modes onto a single structure, maintaining ultra-wideband coverage while satisfying both side-fire and end-fire functions, thus offering multi-functional advantages. This invention uses two exponentially conical slots etched on each dipole arm to form a Vivaldi subarray, which not only improves the antenna gain in Vivaldi mode but also reduces the sidelobes of the high-frequency mode antenna when arrayed with a common-aperture antenna. The design of connecting the tails of the two Vivaldi slots on the dipole arm through slots, sharing a circular resonant cavity and a feed port, not only reduces the complexity of the antenna feed structure but also reduces the number of feed ports. This reduces costs while avoiding interference from complex feed networks to the dipole mode. This invention employs a method of jointly assembling three conformal arrays for the fuselage and one conformal array for the wing. While maintaining high conformal gain, it achieves a maximum beam coverage of 360° × 76° in dipole mode. In Vivaldi mode, it allows for switching between forward and backward beams, as well as switching between horizontal, vertical, and 45° and -45° linear polarization.

[0075] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual-band, dual-mode, ultra-wideband, common-aperture conformal antenna for UAV communication, characterized in that, include: Conformal array antenna for fuselage and conformal array antenna for wing; Both the fuselage conformal array antenna and the wing conformal array antenna are composed of multiple identical dual-frequency dual-mode common-aperture ultra-wideband radiating elements. The dual-band dual-mode common-aperture ultra-wideband radiating element in the fuselage conformal array antenna is configured with a closed curved surface surrounding the fuselage, while the dual-band dual-mode common-aperture ultra-wideband radiating element in the wing conformal array antenna is configured with an open curved surface extending along the wing; the fuselage conformal array antenna and the wing conformal array antenna work together to provide omnidirectional beam coverage and directional beam switching capability; The conformal array antenna of the fuselage includes a cylindrical conformal subarray composed of four dual-frequency dual-mode common-aperture ultra-wideband radiating elements; wherein each dual-frequency dual-mode common-aperture ultra-wideband radiating element is bent along the short side direction, and the four bent radiating elements are arranged at equal angular intervals around the central axis of the conformal cylindrical surface. The fuselage conformal array antenna includes three cylindrical conformal sub-arrays, which are arranged by rotating -90°, 45° and 135° around the central axis, respectively. The conformal array antenna for the wing includes a conformal subarray for the wing composed of four radiating elements, wherein each dual-frequency dual-mode common-aperture ultra-wideband radiating element is bent along the long side, and the four bent radiating elements are arranged in a straight line along the leading edge of the UAV wing.

2. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 1, characterized in that, The dual-frequency dual-mode common-aperture ultra-wideband radiating element includes a rectangular dielectric substrate, a broadband dipole antenna, and two Vivaldi subarrays. The broadband dipole antenna includes a first rectangular radiating patch and a second rectangular radiating patch printed on the upper and lower surfaces of the rectangular dielectric substrate, respectively; two Vivaldi subarrays are integrated on the first and second rectangular radiating patches, respectively; wherein, the broadband dipole antenna is used to support a broadband omnidirectional radiation mode in the low-frequency band, and the two Vivaldi subarrays are used to support a broadband directional end-fire radiation mode in the high-frequency band.

3. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 2, characterized in that, The first rectangular radiating patch and the second rectangular radiating patch are parallel to each other in the thickness direction of the rectangular dielectric substrate, with a spacing of 8 mm and a length of 70 mm.

4. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 2, characterized in that, The broadband dipole antenna further includes an unbalanced feeding structure, which includes a microstrip line printed on the upper surface of the dielectric substrate. One end of the microstrip line is connected to the middle of the first rectangular radiating patch, bends at a predetermined length and extends to the edge of the dielectric substrate, and together with the second rectangular radiating patch, constitutes the unbalanced feeding structure of the dipole antenna.

5. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 2, characterized in that, Each Vivaldi subarray includes two exponential conical slots etched on corresponding rectangular radiating patches and a common circular resonant cavity; the narrow end of each exponential conical slot is connected to the common circular resonant cavity after passing through an elliptical slit and a rectangular slit in sequence.

6. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 5, characterized in that, The Vivaldi subarray also includes a feed structure, which comprises: A gradient microstrip line printed on a corresponding rectangular radiating patch, one end of which is electromagnetically coupled to the common circular resonant cavity; A fan-shaped parasitic structure connected to the other end of the gradient microstrip line is used to achieve impedance matching; In this method, forward end-fired beams or backward end-fired beams can be achieved by selectively feeding the tapered microstrip line.

7. The dual-band dual-mode ultra-wideband common-aperture conformal antenna for UAV communication according to claim 1, characterized in that, The three cylindrical conformal subarrays of the fuselage conformal array antenna work together with the wing conformal subarray of the wing conformal array antenna to form a UAV conformal antenna array, providing omnidirectional beam coverage and directional beam switching capabilities.

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