Broadband wide-angle tight coupling dipole array antenna working in Ka wave band

Abstract

The invention provides a broadband wide-angle tight coupling dipole array antenna working at a Ka wave band. The broadband wide-angle tight coupling dipole array antenna is composed of a plurality of antenna units arranged in a matrix mode. Each unit comprises a single-layer Rogers 5880 dielectric substrate, a bottom-layer metal floor, an upper-layer wide-angle matching layer and a tight dipole radiation layer; wherein the tail ends of vibration arms of the bow-tie-type dipole units are mutually overlapped to enhance coupling, the hyperbolic impedance transformers realize conversion from unbalance to balance and broadband matching, the short-circuit metal wires inhibit common-mode resonance, and the wide-angle matching layer is a frequency selective surface formed by rectangular metal patches. Passive edge units are additionally arranged on the two sides of the array, outer side short-circuit lines are removed to slow down the truncation effect, the metal wall and the floor are integrally machined, the active standing-wave ratio within 27.5-35 GHz is smaller than or equal to 2.1 when + / -50-degree scanning is supported, and the efficiency is larger than or equal to 80%. The antenna has the advantages of low profile, high integration, wide bandwidth angle and high radiation efficiency, and is suitable for a millimeter wave communication system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mobile communication technology, in particular to a wideband wide-angle tightly coupled dipole array antenna working in Ka band. BACKGROUND

[0002] With the accelerated deployment of the fifth generation (5G) and future 6G mobile communication systems, the demand for high data rate, low latency and wide area coverage capability of wireless communication is increasingly urgent. The millimeter wave frequency band (especially the Ka band 27.5-35 GHz) has become a key spectrum to support ultra-high speed transmission due to its abundant continuous bandwidth resources. However, millimeter wave signals have large propagation loss and weak penetration ability, and need to rely on high-performance array antennas to realize directional beamforming and wide-angle scanning to ensure effective coverage and link reliability. Therefore, developing an array antenna suitable for the millimeter wave frequency band with wideband, wide-angle, low profile and easy integration has become a core challenge in the current communication hardware field.

[0003] Existing wideband array antenna technologies mainly fall into two categories: one adopts a three-dimensional feeding structure or a multi-layer dielectric substrate to achieve wideband matching, which performs well in the microwave frequency band, but its three-dimensional structure results in a high profile and large volume, making it difficult to meet the requirements of compactness and conformal integration for terminal devices; the other is a planar tightly coupled dipole array, which has the advantages of simple structure, natural wideband and planarization, but existing solutions are mostly focused on microwave or low millimeter wave frequency bands below 30 GHz, and have not effectively solved the key problems in the Ka band.

[0004] Specifically, there are three technical bottlenecks in realizing wideband wide-angle scanning in the Ka band: first, due to the extremely short wavelength (about 8-11 mm), the size and spacing of the antenna elements are highly constrained, and when scanning at a large angle, the active environment of the elements changes dramatically, resulting in severe input impedance mismatch and significant deterioration of the active standing wave ratio, making it difficult to maintain stable radiation performance within the full frequency band; second, the loss of traditional impedance matching networks increases sharply at high frequencies, and conventional microstrip or coplanar structures are difficult to simultaneously achieve low reflection and low insertion loss within a wide frequency range; third, in actual systems, the array has a finite size, and the edge elements produce strong truncation effects due to periodic interruption, causing distortion of the directional diagram, lifting of the sidelobe, and deviation of the beam pointing, which seriously affects the scanning accuracy.

[0005] Although some studies attempt to alleviate the above problems by introducing passive edge elements, multi-layer substrates or complex feeding networks, they often sacrifice structural simplicity, increase profile height or increase manufacturing cost, which is contrary to the comprehensive demand of millimeter wave terminals for "low profile, high integration and low cost".

[0006] In summary, the prior art still lacks a tight-coupling array antenna scheme that can simultaneously consider wideband operation (27.5-35 GHz), wide-angle scanning of more than ±50°, single-layer low-profile structure, high radiation efficiency, and good edge stability in Ka band. Therefore, it is urgent to propose a new millimeter wave array antenna architecture to break through the current technical bottleneck and meet the practical application requirements of the next generation of wireless communication systems through multi-dimensional collaborative innovation in unit design, matching mechanism, edge processing, and system integration. SUMMARY

[0007] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a wideband wide-angle tight-coupling dipole array antenna operating in Ka band, which solves the problem that the millimeter wave array antenna in the prior art is difficult to simultaneously consider wideband operation, wide-angle beam scanning, low-profile structure, stable impedance matching, and effective suppression of edge truncation effect and common mode resonance.

[0008] To achieve the above-mentioned purpose and other related purposes, the present application provides the following technical solutions: A wideband wide-angle tight-coupling dipole array antenna operating in Ka band is composed of a plurality of antenna units arranged in a matrix, the antenna unit comprising: a dielectric substrate; a metal ground plane located on the bottom layer of the dielectric substrate, the metal ground plane being used to constrain the lateral diffusion of electromagnetic energy and improve the radiation efficiency of the antenna; a wide-angle matching layer disposed above the dielectric substrate, the wide-angle matching layer being composed of a frequency selective surface formed by a plurality of parallelly arranged rectangular metal patches; a tight-coupling dipole radiation layer disposed on the dielectric substrate, comprising a bowtie dipole unit, a hyperbolic impedance transformer, and a short-circuit metal line; the ends of the vibration arms of adjacent bowtie dipole units overlap each other to enhance the coupling between the bowtie dipole units and expand the operating bandwidth; the hyperbolic impedance transformer is connected between the feeding port and the bowtie dipole unit, used to realize non-balanced to balanced signal conversion and wideband impedance matching in Ka band; the short-circuit metal line connects the bowtie dipole unit and the metal ground plane, used to suppress common mode resonance; wherein the electromagnetic signal is input via the feeding port, the bowtie dipole unit is excited to radiate by the hyperbolic impedance transformer, and radiates to the free space through the wide-angle matching layer, thereby realizing wideband wide-angle beam scanning in Ka band.

[0009] To achieve the technical solutions described above, the array antenna works in the manner that electromagnetic signals are input from a feed port, non-balance-to-balance signal conversion is performed through a hyperbolic impedance transformer, and wideband impedance matching in the Ka band is achieved, so as to effectively excite the radiation of electromagnetic waves by the bowtie dipole unit; the ends of the arms of adjacent bowtie dipole units overlap with each other, the inter-unit coupling is enhanced, and the working bandwidth of the antenna is expanded; the radiated electromagnetic waves pass through a wide-angle matching layer located above the dielectric substrate, and are finally radiated to the free space; meanwhile, a metal ground plate is located at the bottom of the dielectric substrate, and is used for restraining the lateral diffusion of electromagnetic energy and improving the radiation efficiency; a short-circuit metal line connects the bowtie dipole unit and the metal ground plate, and suppresses common-mode resonance. Through the synergistic effect of the above structure, the array antenna has the capabilities of wideband, high efficiency and wide-angle beam scanning in the Ka band.

[0010] In an embodiment of the present application, the array antenna is a finite large planar array, and a row of antenna units not participating in feeding is arranged on each side of the array antenna, and the antenna units not participating in feeding are used to alleviate the edge truncation effect of the array antenna.

[0011] To achieve the technical solutions described above, the array antenna is arranged in a finite large planar manner, and a row of antenna units not participating in feeding is arranged on each side of the array antenna; these passive antenna units do not receive a feed signal, but their electromagnetic response is coupled with that of the active units, which effectively extends the electrical size of the array, thereby effectively compensating for the current distribution distortion and surface wave reflection caused by the sudden truncation of the array edge. This design significantly alleviates the edge truncation effect, improves the symmetry and scanning stability of the array pattern, especially at large angles of scanning, and can reduce the sidelobe level and improve the beam pointing accuracy, while not requiring an additional feeding network, and the structure is simple and easy to integrate.

[0012] In an embodiment of the present application, each of the antenna units is configured with an independent SSMP-J radio frequency connector for realizing multi-channel phased feeding.

[0013] To achieve the technical solutions described above, each of the antenna units is configured with an independent SSMP-J radio frequency connector, so that each unit can be connected to an independent feeding channel; the amplitude and phase of the signals of each channel are controlled by an external phased system, so as to realize electronic scanning of the array antenna beam in space. This design supports flexible multi-channel phased feeding, avoids the mutual coupling and bandwidth limitation caused by the traditional common feeding network, improves the beam control accuracy and system integration; at the same time, the SSMP-J radio frequency connector has good high-frequency performance and compact structure, is suitable for high-frequency applications in the Ka band, ensures efficient and low-loss feeding of wideband signals, and thus guarantees the stable working performance of the array under wide-angle scanning.

[0014] In an embodiment of the present application, the width of the rectangular metal patch in the wide-angle matching layer is 1.25 mm, and the spacing between adjacent metal patches is 0.25 mm.

[0015] The above technical solution is implemented, the width of the rectangular metal patch in the wide-angle matching layer is set to 1.25 mm, and the spacing between adjacent metal patches is set to 0.25 mm, so that the frequency selective surface exhibits optimized equivalent electromagnetic characteristics in the Ka band; the specific combination of geometric parameters effectively regulates the phase and impedance response of the incident electromagnetic wave, enhances the impedance matching capability of the antenna at large scanning angles, and at the same time maintains the high transmissivity of the wide-angle matching layer to the radiated signal; thus, without introducing additional active or complex structures, the radiation efficiency and standing wave performance of the array antenna under wideband and wide-angle working conditions are significantly improved, ensuring stable and efficient electromagnetic energy radiation in the Ka band 27.5-35 GHz range.

[0016] In an embodiment of the present application, the short-circuit metal line is removed from the outermost antenna unit of the array to alleviate the edge truncation effect.

[0017] The above technical solution is implemented, by removing the short-circuit metal line from the outermost antenna unit of the array, the current distribution and grounding characteristics of the edge unit are adjusted, so that its electromagnetic response is closer to that of the internal unit in an infinite array, thereby effectively alleviating the edge truncation effect caused by the abrupt change of the array boundary; this design avoids the problems of enhanced edge reflection and pattern distortion caused by the traditional full-array uniform retention of the short-circuit metal line, improves the beam symmetry and sidelobe performance at large angles of scan without increasing the complexity of additional structures or feed, and improves the radiation stability and scan consistency of the entire array under wide-angle working conditions in the Ka band.

[0018] In an embodiment of the present application, when performing ±50° electronic beam scanning in the E plane, the active standing wave ratio of the array antenna in the Ka band 27.5-35 GHz is not greater than 2.1, and the total radiation efficiency is not less than 80%.

[0019] The above technical solution is implemented, when the array antenna performs ±50° electronic beam scanning in the E plane, the antenna achieves excellent wideband and wide-angle matching and radiation performance in the Ka band 27.5-35 GHz range; under this working condition, the active standing wave ratio of the array antenna is always not greater than 2.1, indicating that the impedance matching between the feed port and the free space is good, and the reflection loss is low; at the same time, the total radiation efficiency is not less than 80%, indicating that the electromagnetic energy is effectively converted into radiated power, and the transverse leakage and dielectric / conductor loss are effectively suppressed. This performance indicator fully reflects the high efficiency and high stability advantages of the present application in high-frequency wide-angle phased array applications, meeting the actual needs of Ka-band satellite communication, radar and other systems for wideband, high-efficiency and large-angle scanning antennas.

[0020] In an embodiment of the present application, an air gap is arranged between the wide-angle matching layer and the tight-dipole radiating layer to adjust the electromagnetic coupling strength to achieve wide-angle matching.

[0021] The above technical solution is implemented by arranging an air gap between the wide-angle matching layer and the tight-dipole radiating layer to form a non-contact double-layer structure. The air gap serves as a regulation area of electromagnetic coupling, effectively adjusting the interaction strength between the dipole radiating unit and the frequency selective surface. When working in the Ka band, the gap avoids impedance mismatch and surface wave enhancement caused by direct dielectric loading, so that the wide-angle matching layer can more effectively optimize the input impedance characteristics under wide-angle scanning, thereby improving the impedance stability and radiation consistency of the array antenna under wide-angle scanning without introducing additional loss materials or complex feed networks, further supporting the performance goals of wideband, high efficiency and wide-angle beam scanning in the Ka band.

[0022] In an embodiment of the present application, a metal wall surrounding the array antenna is further included, the metal wall and the metal floor are CNC integrally processed and formed to constitute an electromagnetic shielding cavity; the dielectric substrate is fixed to the metal wall by fasteners; and the short-circuit metal line and the backside metal structure of the hyperbolic impedance transformer are electrically connected to the metal wall.

[0023] The above technical solution is implemented by arranging a metal wall surrounding the array antenna and CNC integrally processed and formed with the metal floor to form a closed electromagnetic shielding cavity, effectively suppressing external interference and array edge electromagnetic energy leakage. The dielectric substrate is fixed to the metal wall by fasteners to ensure structural stability and high-frequency grounding continuity. At the same time, the short-circuit metal line and the backside metal structure of the hyperbolic impedance transformer are electrically connected to the metal wall, making the common-mode current path low-impedance closed to further enhance the common-mode resonance suppression capability and provide a stable high-frequency reference ground for the feed network. The above structure cooperates to improve the radiation efficiency, impedance stability and environmental adaptability of the Ka-band array antenna without adding additional shielding components, while simplifying the assembly process and ensuring the consistency and reliability of the wide-angle scanning performance.

[0024] In an embodiment of the present application, the dielectric substrate is a single-layer Rogers 5880 dielectric substrate with a dielectric constant of 2.2, a loss tangent of 0.0009 and a thickness of 0.252 mm.

[0025] The above technical solution is realized by using a single-layer Rogers 5880 dielectric substrate with a dielectric constant of 2.2, a loss tangent of 0.0009 and a thickness of 0.252 mm. The material combination has extremely low dielectric loss and stable electromagnetic properties in the Ka band. Low dielectric constant helps to reduce surface wave propagation and improve unit isolation. Ultra-low loss tangent significantly reduces energy dissipation during high-frequency conduction and radiation. Precise control of the thin thickness (0.252 mm) is conducive to realizing a compact planar structure and optimizing the impedance matching between the dipole unit and the ground plate. The above parameters work together to effectively support the array antenna to realize the comprehensive performance of wideband, high efficiency and wide-angle scanning in the Ka band 27.5-35 GHz without introducing multi-layer stacking or complex processing technology.

[0026] As described above, the wideband and wide-angle tight-coupling dipole array antenna operating in the Ka band has the following beneficial effects: The synergistic optimization of millimeter wave frequency band wideband and wide-angle scanning performance: by overlapping the adjacent lead knot type dipole unit arm ends, the inter-unit coupling is enhanced, and the operating bandwidth is effectively expanded. The non-balance to balance signal conversion and Ka band wideband impedance matching are realized by combining the hyperbolic impedance transformer, and the electromagnetic response under large-angle scanning is regulated by using the wide-angle matching layer (frequency selective surface) composed of rectangular metal patches, which significantly suppresses the deterioration of standing wave ratio caused by impedance mutation during wide-angle scanning. The actual measurement shows that under the condition of E-plane ± 50° electronic beam scanning, the active standing wave ratio of the array antenna in the frequency band of 27.5-35 GHz is not greater than 2.1, and the total radiation efficiency is not less than 80%, successfully meeting the dual requirements of “wideband transmission” and “wide-angle coverage” for millimeter wave communication.

[0027] Low profile and high integration structure: a single-layer Rogers 5880 dielectric substrate (dielectric constant 2.2, loss tangent 0.0009, thickness 0.252 mm) is used to realize a compact planar structure while ensuring low dielectric loss; the double hyperbolic impedance transformer is integrated into the feed layer, which can complete the wideband matching between coaxial feed and dipole without external balun, simplifying the feed network; the metal ground plate and the metal wall surrounding the array are formed by CNC integrated machining, which not only forms an electromagnetic shielding cavity to improve environmental adaptability, but also ensures the assembly precision required in the millimeter wave frequency band; the dielectric substrate is fixed to the metal wall by fasteners, and the overall structure is stable and easy to assemble in batches. Compared with the traditional scheme relying on multi-layer substrate or three-dimensional feed, the present application significantly reduces the antenna profile height and manufacturing complexity, and is more suitable for the requirements of modern communication terminals for miniaturization and high integration.

[0028] The edge effect and common mode interference are effectively inhibited: one row of antenna units not participating in feeding is added on each side of the finite planar array, and the short-circuit metal wire on the side far from the array center of the outermost unit is removed, so as to specifically alleviate the current distortion and pattern distortion caused by the array boundary truncation; meanwhile, the short-circuit metal wire connects the bow-tie dipole unit and the metal structure (metal floor or metal wall), so that the common mode resonance is moved out of the working frequency band, the interference of the common mode current on the radiation performance is effectively inhibited, and the beam stability and pointing accuracy under wide-angle scanning are ensured.

[0029] In summary, the present application successfully solves the comprehensive technical problems of the existing millimeter wave array antenna in terms of wideband, wide angle, low profile, high efficiency and edge stability, etc. without increasing the structural complexity, through multi-dimensional collaborative innovation of unit design, array layout, matching mechanism and mechanical integration, and can provide reliable and efficient antenna solutions for 5G / 6G millimeter wave communication, satellite terminal and other high-performance application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a three-dimensional structure diagram of the antenna unit.

[0031] Figure 2 is a rear view of the antenna unit.

[0032] Figure 3 is the measured active standing wave ratio of the array center unit according to the array shown in Figure 1 , 2

[0033] Figure 4 is the total efficiency of the array center unit in the E-plane scanning according to the array shown in Figure 1

[0034] Figure 5 is a structure diagram of the 5x5 array of the present application.

[0035] Figure 6 is another structure diagram of the 5x5 array of the present application.

[0036] Figure 7 is the measured active standing wave ratio of the array center unit according to the array shown in Figure 5 , 6

[0037] Figure 8 is the scanning pattern of the array in the E-plane according to the processed array shown in Figure 5 , 6 DETAILED DESCRIPTION

[0038] ​​​​The following embodiments and features of the embodiments can be combined with each other without conflict, as long as there is no conflict.

[0039] Referring to Figures 1-2 The present application provides a broadband wide-angle tightly coupled dipole array antenna working in Ka band, which is composed of a plurality of antenna units arranged in a matrix. The antenna unit comprises a dielectric substrate, a metal ground plate located at the bottom of the dielectric substrate, which is used to constrain the lateral diffusion of electromagnetic energy and improve the radiation efficiency of the antenna, a wide-angle matching layer arranged above the dielectric substrate, which is composed of a frequency selective surface of a plurality of rectangular metal patches arranged in parallel, a tightly coupled dipole radiation layer arranged on the dielectric substrate, which comprises a bowtie dipole unit, a hyperbolic impedance transformer and a short-circuit metal line, the ends of the adjacent arms of the bowtie dipole unit overlap each other to enhance the coupling between the bowtie dipole units and expand the operating bandwidth, and the hyperbolic impedance transformer is connected between the feeding port and the bowtie dipole unit to realize non-balanced to balanced signal conversion and wideband impedance matching in the Ka band.

[0040] The short-circuit metal line connects the bowtie dipole unit and the metal ground plate to suppress common-mode resonance. Electromagnetic signals are input via the feeding port, excited by the hyperbolic impedance transformer to radiate the bowtie dipole unit, and radiated to the free space through the wide-angle matching layer, thereby realizing wideband wide-angle beam scanning in the Ka band.

[0041] When the array antenna works, electromagnetic signals are input via the feeding port, non-balanced to balanced signal conversion is performed by the hyperbolic impedance transformer, and wideband impedance matching in the Ka band is realized, thereby effectively exciting the bowtie dipole unit to radiate electromagnetic waves. The ends of the adjacent arms of the bowtie dipole unit overlap each other to enhance the coupling between the units and expand the operating bandwidth of the antenna. The radiated electromagnetic waves pass through the wide-angle matching layer located above the dielectric substrate and are finally radiated to the free space. At the same time, the metal ground plate is located at the bottom of the dielectric substrate to constrain the lateral diffusion of electromagnetic energy and improve the radiation efficiency. The short-circuit metal line connects the bowtie dipole unit and the metal ground plate to suppress common-mode resonance.

[0042] Through the synergistic effect of the above structure, the array antenna has the capabilities of wideband, high efficiency and wide-angle beam scanning in the Ka band. The array antenna is a finite planar array, and a row of antenna units not participating in feeding is arranged on each side of the array antenna, which is used to alleviate the edge truncation effect of the array antenna. The key structural parameters of the antenna unit are: w1=1.25mm, w d= 1.22 mm, h1 = 3.44 mm, w c = 0.15 mm, wf1 = 0.7 mm, t = 0.252 mm, d x = 4.5 mm, d y = 4.5 mm, g1 = 0.25 mm, w s1 = 0.39 mm, wf2 = 2.1 mm, h2 = 2.3 mm.

[0043] The array antenna is arranged in a limited plane, and one row of antenna units not participating in feeding is additionally arranged on each side of the array antenna; the passive antenna units do not receive a feeding signal, but the electromagnetic response thereof is coupled with the active units, so that the electrical size of the array is equivalently lengthened, thereby effectively compensating for the current distribution distortion and surface wave reflection caused by the sudden truncation of the array edge. The design significantly slows down the edge truncation effect, improves the symmetry and scanning stability of the array directional diagram, reduces the sidelobe level and improves the beam pointing accuracy, especially at a large angle of scanning, and simultaneously does not require an additional feeding network, so that the structure is simple and easy to integrate.

[0044] Each of the antenna units is configured with an independent SSMP-J radio frequency connector for realizing multi-channel phased feeding, so that each antenna unit can be respectively connected to an independent feeding channel; the amplitude and phase of the signals of each channel are controlled by an external phased system, so as to realize electronic scanning of the array antenna beam in space. The design supports flexible multi-channel phased feeding, avoids the mutual coupling and bandwidth limitation caused by the traditional common feeding network, improves the beam control accuracy and system integration; meanwhile, the SSMP-J radio frequency connector has good high-frequency performance and a compact structure, is suitable for high-frequency applications in the Ka band, ensures efficient and low-loss feeding of the wideband signal, and thereby guarantees the stable working performance of the array at a wide angle of scanning.

[0045] In the wide-angle matching layer, the width of the rectangular metal patch is 1.25 mm, and the spacing between adjacent metal patches is 0.25 mm, so that the frequency selective surface has optimized equivalent electromagnetic characteristics in the Ka band; the specific combination of geometric parameters effectively controls the phase and impedance response of the incident electromagnetic wave, enhances the impedance matching capability of the antenna at a large scanning angle, and simultaneously maintains the high transmissivity of the wide-angle matching layer to the radiation signal; thereby, without introducing additional active or complex structures, the radiation efficiency and standing wave performance of the array antenna under the condition of wide bandwidth and wide angle are significantly improved, so as to ensure stable and efficient electromagnetic energy radiation in the Ka band of 27.5-35 GHz.

[0046] The short-circuit metal wires at the outermost antenna units of the array are removed to alleviate the edge truncation effect. By removing the short-circuit metal wires at the outermost antenna units of the array, the current distribution and grounding characteristics of the edge units are adjusted, so that the electromagnetic response is closer to that of the internal units in an infinite array, thereby effectively alleviating the edge truncation effect caused by the abrupt change of the array boundary; the design avoids the problems of enhanced edge reflection and pattern distortion caused by the traditional full-array uniform retention of short-circuit metal wires, improves the beam symmetry and sidelobe performance at large angles of scan without increasing the complexity of additional structures or feed, and improves the radiation stability and scan consistency of the entire array at a wide angle of scan in the Ka band.

[0047] When the electronic beam is scanned in the E plane by ±50°, the active standing wave ratio of the array antenna in the Ka band 27.5-35 GHz is not greater than 2.1, and the total radiation efficiency is not less than 80%. When the electronic beam is scanned in the E plane by ±50°, the antenna units achieve excellent wideband wide-angle matching and radiation performance in the Ka band 27.5-35 GHz; under this working condition, the active standing wave ratio of the array antenna is always not greater than 2.1, indicating that the impedance matching between the feed port and the free space is good, and the reflection loss is low; at the same time, the total radiation efficiency is not less than 80%, indicating that the electromagnetic energy is effectively converted into radiation power, and the transverse leakage and dielectric / conductor loss are effectively suppressed. This performance index fully reflects the high efficiency and high stability advantage of the application in high-frequency wide-angle phased array applications, and meets the actual needs of Ka-band satellite communication, radar and other systems for wideband, high-efficiency and wide-angle scanning antennas.

[0048] An air gap is provided between the wide-angle matching layer and the tight dipole radiation layer for adjusting the electromagnetic coupling strength to achieve wide-angle matching. By providing an air gap between the wide-angle matching layer and the tight dipole radiation layer, a non-contact double-layer structure is formed, and the air gap serves as a regulation area for electromagnetic coupling, effectively adjusting the interaction strength between the dipole radiation unit and the frequency selective surface; when working in the Ka band, the gap avoids the impedance mismatch and surface wave enhancement caused by direct dielectric loading, so that the wide-angle matching layer can more effectively cooperatively optimize the input impedance characteristics under wide-angle scanning, thereby improving the impedance stability and radiation consistency of the array antenna under wide-angle scanning without introducing additional loss materials or complex feed networks, and further supporting the performance goal of realizing wideband, high-efficiency and wide-angle beam scanning in the Ka band.

[0049] Further comprising a metal wall surrounding the array antenna, the metal wall and the metal floor are integrally processed by CNC to form an electromagnetic shielding cavity; the dielectric substrate is fixed on the metal wall by fasteners; the backside metal structure of the hyperbolic impedance transformer and the short-circuit metal line are electrically connected to the metal wall. By setting a metal wall surrounding the array antenna and integrally processed with the metal floor by CNC, a closed electromagnetic shielding cavity is formed to effectively suppress external interference and array edge electromagnetic energy leakage; the dielectric substrate is fixed on the metal wall by fasteners to ensure structural stability and high-frequency grounding continuity; at the same time, the backside metal structure of the hyperbolic impedance transformer and the short-circuit metal line are electrically connected to the metal wall to make the common-mode current path low-impedance closed, further enhancing the common-mode resonance suppression capability and providing a stable high-frequency reference ground for the feed network. The above-mentioned structures work together to improve the radiation efficiency, impedance stability and environmental adaptability of the Ka-band array antenna without adding additional shielding components, while simplifying the assembly process and ensuring the consistency and reliability of the wide-angle scanning performance.

[0050] The dielectric substrate is a single-layer Rogers 5880 dielectric substrate with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.252 mm. The single-layer Rogers 5880 dielectric substrate has a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.252 mm. This material combination has extremely low dielectric loss and stable electromagnetic properties in the Ka band. Low dielectric constant helps to reduce surface wave propagation and improve unit isolation, ultra-low loss tangent significantly reduces energy dissipation during high-frequency conduction and radiation, and precisely controlled thin thickness (0.252 mm) is conducive to realizing a compact planar structure and optimizing the impedance matching between the dipole unit and the ground plate. The above parameters work together to effectively support the array antenna to achieve wideband, high efficiency and wide-angle scanning in the Ka band 27.5-35 GHz range without introducing multi-layer stacking or complex processing.

[0051] According to the antenna unit structure as shown in Figures 1-2 , the active standing wave ratio of the center unit of the infinite tightly coupled dipole array obtained by simulation using the unit cell periodic boundary condition of the commercial software CST at different scanning angles is as shown in Figure 3 , when the E-plane scanning angle is 0°, the active standing wave ratio of 27.5-35 GHz is about 2.1; when the scanning angle is 30°, the active standing wave ratio of 27.5-35 GHz is about 1.4; when the scanning angle is 50°, the active standing wave ratio of 27.5-35 GHz is about 1.2. According to the simulation results, as the scanning angle increases, the coupling effect between the antenna units gradually weakens, which improves the matching performance of the antenna units.

[0052] When an infinite array is scanned on the E-plane, the overall efficiency of the central cell is as follows: Figure 4 As shown, within the operating frequency band, the overall efficiency of the antenna is greater than 80% in the 0-50° range. As the scanning angle increases, the antenna efficiency gradually increases, indicating that the coupling between elements gradually weakens, leading to an improvement in antenna efficiency.

[0053] The diagram of the wide bandwidth angle-tightly coupled dipole array structure operating in the Ka band is shown below. Figures 5-6 As shown, the array consists of Figure 1 The 5×5 array formed by the shown unit structure has an additional row of sub-elements at each end to mitigate edge effects of the finite-sized array. Since there are no adjacent units to the left and right of the edge units, the short-circuit metal lines on the outer sides of the units at both ends of the array are removed. The metal walls and metal floor are machined using a CNC integrated process. Two through holes are drilled in the metal wall of each unit, and the PCB is fixed to the metal wall using an M0.8 metal screw set. Screw holes are drilled in the metal floor of each unit for mounting the SSMP-J RF connector. The length L = 31.5mm, width W = 22.5mm, and height h of the metal floor are... gnd =4.6mm.

[0054] according to Figures 1-2 The antenna element structure shown, after fabrication and assembly, has a central element standing wave ratio (SWR) measured using a vector network analyzer. Figure 7 As shown, within the operating frequency band, the standing wave ratio of the central unit is less than 3, and the simulated standing wave ratio is less than 2. The trend of the standing wave ratio obtained from the simulation test is quite consistent, which indicates that the array can achieve impedance matching in a wide frequency band.

[0055] The radiation pattern during scanning of a tightly coupled dipole array is as follows: Figure 8 As shown, the E-plane radiation pattern of the array antenna at 28 GHz was obtained using unit testing methods and the pattern product theorem synthesis. Data shows that the array can scan up to 50°. In side-firing mode, the simulated peak gain is 18.54 dBi, and the measured peak gain is 15.13 dBi, with a gain difference of 3.41 dB. When scanning 30° in the E-plane, the simulated peak gain is 16.96 dBi, and the measured peak gain is 15.61 dBi, with a gain difference of 1.35 dB. When scanning 50° in the E-plane, the simulated peak gain is 16.41 dBi, and the measured peak gain is 14.14 dBi, with a gain difference of 2.27 dB. This verifies the array's ±50° wide-angle scanning capability and gain stability in the E-plane.

[0056] The application provides a broadband wide-angle tightly coupled dipole array antenna working in Ka band. The antenna uses end overlapping structure between dipoles to offset the influence of metal ground on radiation performance in low profile, uses hyperbolic impedance transformer to realize feeding of knot type dipole and completes non-balance to balance conversion, uses wide-angle matching layer to complete impedance matching of the array during scanning, uses CNC machining process to realize integrated machining of metal wall and metal floor, and finally uses SSMP-J radio frequency connector to independently feed each port. Through the above design method, the tightly coupled dipole array working in Ka band can realize wide-angle scanning in a wide band range.

[0057] The above embodiments only exemplarily illustrate the principles and effects of the application, and are not used to limit the application. All equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the application should be covered by the claims of the application.

Claims

1. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band, comprising a plurality of antenna elements arranged in a matrix, characterized in that, The antenna element includes, Dielectric substrate; A metal ground plane located at the bottom of the dielectric substrate is used to constrain the lateral diffusion of electromagnetic energy and improve the antenna radiation efficiency. A wide-angle matching layer disposed above the dielectric substrate, the wide-angle matching layer being a frequency selection surface composed of a plurality of parallel rectangular metal patches; The tight dipole radiating layer disposed on the dielectric substrate includes a bowtie dipole unit, a hyperbolic impedance transformer, and a short-circuit metal line. The arms of adjacent bowtie dipole units overlap each other to enhance the coupling between bowtie dipole units and extend the operating bandwidth. The hyperbolic impedance transformer is connected between the feed port and the bowtie dipole unit to realize unbalanced to balanced signal conversion and broadband impedance matching in the Ka band. The short-circuit metal wire connects the bowtie-shaped dipole unit to the metal ground plane to suppress common-mode resonance; The electromagnetic signal is input through the feed port, excites the bowtie dipole unit to radiate through the hyperbolic impedance transformer, and is radiated into free space through the wide-angle matching layer, thereby achieving wide-bandwidth wide-angle beam scanning in the Ka band.

2. The wide bandwidth angle-tightly coupled dipole array antenna operating in the Ka band according to claim 1, characterized in that, The array antenna is a finite-size planar array, with a row of antenna elements that do not participate in the feeding on each side. The antenna elements that do not participate in the feeding are used to mitigate the edge truncation effect of the array antenna.

3. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, Each antenna element is configured with an independent SSMP-J RF connector for multi-channel phased-controlled feeding.

4. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, In the wide-angle matching layer, the width of the rectangular metal patch is 1.25mm, and the spacing between adjacent metal patches is 0.25mm.

5. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, The short-circuited metal wire is removed from the outermost antenna element of the array to mitigate the edge cutoff effect.

6. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, When performing ±50° electronic beam scanning in the E-plane, the active standing wave ratio of the array antenna in the Ka band 27.5-35 GHz is no greater than 2.1, and the total radiation efficiency is no less than 80%.

7. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, An air gap is provided between the wide-angle matching layer and the tight dipole radiation layer to adjust the electromagnetic coupling strength to achieve wide-angle matching.

8. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, It also includes a metal wall surrounding the array antenna, the metal wall and the metal floor being integrally machined by CNC and forming an electromagnetic shielding cavity; the dielectric substrate is fixed to the metal wall by fasteners; the short-circuit metal line and the back metal structure of the hyperbolic impedance transformer are both electrically connected to the metal wall.

9. A wide-bandwidth, tightly coupled dipole array antenna operating in the Ka-band according to claim 1, characterized in that, The dielectric substrate is a single-layer Rogers 5880 dielectric substrate with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.252 mm.

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