An ultra-wideband phased array antenna unit

Abstract

An ultra-wideband phased array antenna element includes a single-polarized antenna element, two single-polarized antenna elements are cross-placed to form a dual-polarized tightly coupled phased array antenna element, the dual-polarized tightly coupled phased array antenna element is placed on an X-shaped groove in the middle of a metal structure, the metal structure serves as the ground plane of the dual-polarized tightly coupled phased array antenna element, and a compatible third dielectric substrate is covered on the metal structure. The surface of the third dielectric substrate is embedded with a first resistive frequency selective surface and a second resistive frequency selective surface, the second resistive frequency selective surface is covered with a copper layer, and finally, a PP sheet is used to bond the third dielectric substrate and a fourth dielectric substrate. The introduction of the resistive frequency selective surface in this invention greatly widens the antenna operating bandwidth, and the director can improve the antenna ground radiation efficiency. This antenna element has a 9-fold ultra-wideband operating bandwidth for practical engineering applications, a large scanning range of 45° between the E-plane and H-plane, excellent port isolation, relatively low cross-polarization, and high radiation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology and relates to an ultra-wideband phased array antenna unit that can be applied to the field of microwave communication. Background Technology

[0002] In modern wireless communication systems, antenna technology, as a crucial component, is widely used in mobile communications. Phased array antennas, a type of array antenna, are high-performance antenna technologies that achieve beam directionality, scanning, and multi-target tracking by controlling the phase of each element in the antenna array. Traditional phased array antennas typically use a narrow bandwidth for beam control and signal transmission. However, with increasing communication demands and spectrum resources, traditional narrowband phased array antennas are increasingly unable to meet the requirements of modern high-frequency communication systems in high-speed, low-latency, and long-distance communication applications. Therefore, research on ultra-wideband (UWB) has been a hot topic in recent years. UWB phased array antennas, as an emerging technology, combine the high data transmission rate of UWB communication with the rapid beam adjustment advantages of phased array antennas, providing a solution for achieving high-speed data transmission and rapid beam scanning over a wide bandwidth. This combination enables UWB communication to not only achieve high data rate transmission and low latency, flexibly addressing the needs of multi-target detection and tracking in dynamic environments, but also possess stronger anti-interference capabilities and higher precision positioning and imaging capabilities. Research on ultra-wideband phased array technology has significant advantages in improving radar and detection capabilities, enhancing medical imaging technology, promoting autonomous driving and intelligent transportation, and driving the development of communication technology, which are currently hot research areas. [Zhong J, Johnson A, Alwan EA, et al. Dual-linearpolarized phased array with 9:1 bandwidth and 60° scanning off broadside[J].IEEE Transactions on Antennas and Propagation, 2019, 67(3): 1996-2001.] proposed an ultra-wideband tightly coupled phased array antenna, whose antenna element is a dipole antenna. Although it can achieve a 9:1 operating bandwidth, its element size is 0.48 times that of the high-frequency wavelength, which will increase the cost of the radar system; [Johnson AD, Zhong J, Venkatakrishnan SB, et al. Phased array with low-angle scanning and 46:1 bandwidth[J].IEEE Transactions on Antennas and Propagation, 2020, 68(12): 7833-7841] proposed a phased array antenna with an ultra-wideband of 46:1, which has a wide operating bandwidth but its efficiency is only 70%. Therefore, the research and development of ultra-wideband phased array antenna technology has significant theoretical and practical value. Summary of the Invention

[0003] To overcome the shortcomings of the existing technology, the present invention proposes an ultra-wideband phased array antenna. By adopting a tightly coupled design method, introducing a resistive frequency selection surface to broaden the bandwidth, and adding a director to improve radiation efficiency, an ultra-wideband operating bandwidth of 9 times the frequency is successfully achieved. It has the advantages of low cost, high radiation efficiency, and large operating bandwidth.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An ultra-wideband phased array antenna unit includes a single-polarized antenna unit, two single-polarized antenna units are cross-placed to form a dual-polarized tightly coupled phased array antenna unit, the dual-polarized tightly coupled phased array antenna unit is placed on an X-shaped groove in the middle of a metal structure 19, the metal structure 19 serves as the ground of the dual-polarized tightly coupled phased array antenna unit, a compatible third dielectric substrate 18 is covered on the metal structure 19, the surface of the third dielectric substrate 18 is embedded with a first resistive frequency selection surface 17 and a second resistive frequency selection surface 16, the second resistive frequency selection surface 16 is covered with a copper layer 15, and finally a PP sheet 14 is used to bond the third dielectric substrate 18 to a fourth dielectric substrate 13.

[0006] The single-polarized antenna unit includes a first dielectric substrate 3 and a second dielectric substrate 10 bonded together by an interlayer PP sheet 6. A first coupling patch 1 is printed on the upper outer side of the first dielectric substrate 3, and a first balun radiating ground plane 2 is printed on the lower outer side. A second coupling patch 11 is printed on the upper outer side of the second dielectric substrate 10, and a second balun radiating ground plane 12 is printed on the lower outer side. Radiation patches 5 are symmetrically printed on the middle inner sides of both the first dielectric substrate 3 and the second dielectric substrate 10. A stripline balun 4 is printed on the lower inner side of the first dielectric substrate 3, and a frequency selective surface patch 8 is printed on the upper inner side of the second dielectric substrate 10. A director radiation patch 9 is provided above the frequency selective surface patch 8.

[0007] The inter-use PP sheet 6, the first dielectric substrate 3, and the second dielectric substrate 10 are provided with a plurality of metal vias 7. The metal vias 7 are connected to the first balun radiating ground 2 and the second balun radiating ground 12 respectively through the strip balun 4 for power supply.

[0008] The radiation patch 5 is a conical dipole patch.

[0009] Rectangular director radiation patches 9 are printed between the symmetrically printed radiation patches 5.

[0010] The second resistive frequency selection surface 16 is a long rectangular shape, with two layers arranged in a figure-eight pattern on the upper surface of the third dielectric substrate 18. The first resistive frequency selection surface 17 is located between the inner layers of the second resistive frequency selection surface 16 and is distributed at equal intervals at the four corners.

[0011] The first dielectric substrate 3, the second dielectric substrate 10, the third dielectric substrate 18 and the fourth dielectric substrate are made of Taconic TLY.

[0012] The PP sheet 6 and PP sheet 14 used in the room are made of FR-28-0040-50 material.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] The tightly coupled ultra-wideband phased array antenna element used in this invention employs a patch-type frequency selective surface instead of a dielectric layer to increase thickness, thus having a lower profile height. Furthermore, the element size of this design is 9mm, which is 0.54 times the wavelength of the high-frequency 18GHz operating bandwidth. The larger element size can significantly reduce the cost of radar and communication systems.

[0015] The resistive frequency selective surface used in this invention is covered on the metal structure, i.e., the antenna floor, which can effectively eliminate common-mode resonance at the corresponding frequency point, while the absorption of electromagnetic waves at other frequencies is weak. At the same time, it is equipped with a rectangular director patch, achieving an average radiation efficiency of 90% in the 2-18 GHz frequency band.

[0016] This invention uses a double-layer coupling patch to increase the overlap area between the coupling patch and the conical dipole, thereby providing stronger capacitive coupling to broaden the antenna's operating bandwidth.

[0017] This invention utilizes a vertical rectangular frequency selective surface patch to achieve a lightweight design, enhances beam scanning capability, and provides the ability to scan ±45° in both the E-plane and H-plane, while also improving the operating bandwidth of the resistive frequency selective surface.

[0018] In summary, the antenna design of this invention employs a double-layer coupled patch structure. The single-polarization antenna element consists of two dielectric substrates bonded together by a PP layer. The two identical polarized antenna elements are placed crosswise within a bottom metal structure, which serves as the ground plane for the entire antenna element. The upper layer is covered with a resistive frequency-selective surface, effectively expanding the antenna bandwidth. Simulation results of this antenna element at an infinite period boundary show that it can achieve 9th harmonic ±45° scanning, exhibiting advantages such as low cost, high radiation efficiency, and a large operating bandwidth. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the single-polarization unit of the present invention.

[0020] Figure 2 This is a cross-sectional view of the metal structural component and resistive FSS of the present invention.

[0021] Figure 3 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the radiating patch 5 and the rectangular director radiating patch 9 of the present invention.

[0023] Figure 5 This is a schematic diagram of the resistive frequency selective surface structure of the present invention.

[0024] Figure 6 This is a VSWR diagram of the antenna element of the present invention under periodic boundaries, wherein, Figure 6 (a) is the active VSWR of a one-port port. Figure 6 (b) is the active VSWR of the two-port circuit.

[0025] Figure 7 This is a radiation efficiency diagram of the antenna element of the present invention under periodic boundaries.

[0026] Figure 8 This is the cross-polarization diagram of the antenna element under the periodic boundary of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 , Figure 2 , Figure 3 As shown, an ultra-wideband phased array antenna unit includes a single-polarized antenna unit. Two single-polarized antenna units are placed crosswise to form a dual-polarized tightly coupled phased array antenna unit. The dual-polarized tightly coupled phased array antenna unit is placed on an X-shaped groove in the middle of a metal structure 19. The metal structure 19 serves as the ground plane of the dual-polarized tightly coupled phased array antenna unit. A compatible third dielectric substrate 18 is covered on top of the metal structure 19. A first resistive frequency selection surface 17 and a second resistive frequency selection surface 16 are embedded on the surface of the third dielectric substrate 18. A copper layer 15 is covered on the second resistive frequency selection surface 16. Finally, a PP sheet 14 bonds the third dielectric substrate 18 to a fourth dielectric substrate 13.

[0029] The single-polarized antenna unit includes a first dielectric substrate 3 and a second dielectric substrate 10 bonded together by an interlayer PP sheet 6. A first coupling patch 1 is printed on the upper outer side of the first dielectric substrate 3, and a first balun radiating ground plane 2 is printed on the lower outer side. A second coupling patch 11 is printed on the upper outer side of the second dielectric substrate 10, and a second balun radiating ground plane 12 is printed on the lower outer side. Radiation patches 5 are symmetrically printed on the middle inner sides of both the first dielectric substrate 3 and the second dielectric substrate 10. A stripline balun 4 is printed on the lower inner side of the first dielectric substrate 3, and a frequency selective surface patch 8 is printed on the upper inner side of the second dielectric substrate 10. A director radiation patch 9 is provided above the frequency selective surface patch 8.

[0030] The inter-use PP sheet 6, the first dielectric substrate 3, and the second dielectric substrate 10 are provided with a plurality of metal vias 7. The metal vias 7 are connected to the first balun radiating ground 2 and the second balun radiating ground 12 respectively through the strip balun 4 for power supply.

[0031] See Figure 4 The radiation patch 5 is a conical dipole patch.

[0032] Rectangular director radiating patches 9 are printed between the symmetrically printed radiating patches 5. The director structure can increase the forward radiation of the antenna, thereby improving the radiation efficiency of the antenna.

[0033] See Figure 5 The second resistive frequency selection surface 16 is a long rectangular shape, with two layers arranged in a figure-eight pattern on the upper surface of the third dielectric substrate 18. The first resistive frequency selection surface 17 is located between the inner layers of the second resistive frequency selection surface 16 and is distributed at equal intervals at the four corners. This eliminates common-mode resonance in the frequency band and can broaden the working bandwidth of the antenna.

[0034] The first dielectric substrate 3, the second dielectric substrate 10, the third dielectric substrate 18 and the fourth dielectric substrate are made of Taconic TLY.

[0035] The PP sheet 6 and PP sheet 14 used in the room are made of FR-28-0040-50 material.

[0036] The single-polarized antenna element of this invention measures 9mm × 0.608mm × 21.25mm. The substrate material for the dipole portion is Taconic TLY with a dielectric constant of 2.2 and a thickness of 0.601mm. Part of the substrate is embedded in the ground plane to fix the dual-polarized antenna substrate to the metal ground plane, making its structure more stable. The radiating patch 5 is a conical dipole, which has strong forward radiation capability. The conical dipole is 7.25mm high. The coupling patch has a length of 5.5mm and a width of 4.75mm. The vertical frequency-selective surface patch consists of four rectangular patches, each measuring 1.775mm × 1.8mm. The director consists of two rectangular patches, 2mm × 0.5mm and 1mm × 0.5mm respectively, which can improve the radiation efficiency of the antenna. The feed balun is composed of a first balun radiating ground plane 2, a second balun radiating ground plane 12, and a stripline balun 4, achieving broadband impedance transformation.

[0037] like Figure 3As shown, the dual-polarized antenna is composed of two single-polarized antennas intersecting, so the size of a single antenna element is 9mm × 9mm × 21.25mm. The coupling patches of the two polarizations need to be electrically connected by solder. The metal structural component is 9mm × 9mm × 4mm in size and has a hollow design in the middle to facilitate the insertion of the dual-polarized antenna and soldering to the SSMP connector. The dimensions of the third dielectric substrate 18 and the fourth dielectric substrate 13 are 7.2mm × 7.2mm. The resistive frequency selection surface 16 is composed of four rectangular resistive films, each with a size of 4.2mm × 0.8mm, and the resistive frequency selection surface 17 is composed of four square resistive films, each with a size of 0.9mm × 0.9mm. The resistive FSS substrate material is Taconic TLE (covered planar resistive film and planar laminate material), with a dielectric constant of 2.95. The specification of this resistive frequency selection surface is 50Ω / sq.

[0038] To ensure the proper functioning of the dual-polarized tightly coupled antenna stripline, such as Figure 1 As shown, as many metallized vias as possible are made near the stripline balun to connect the upper and lower metal ground planes of the stripline dielectric layer. The radius of the metallized vias is 0.125 mm. Similarly, the double-layer conical dipole radiating patch and the double-layer coupling patch also need to be connected through metallized vias.

[0039] Working principle of the invention:

[0040] This ultra-wideband phased array antenna is a specially designed tightly coupled phased array antenna in which the antenna elements in the array are electromagnetically coupled to each other, and coupling capacitance is introduced through the overlap effect between the conical dipole and the coupling patch. This coupling enhances the capacitive coupling effect between the elements, so that each antenna element not only has electromagnetic interaction with its surrounding elements, but its radiation characteristics and performance are also affected by the neighboring elements, thereby improving performance characteristics such as beamforming, bandwidth, gain, and interference suppression. Its working principle is based on the coupling capacitance introduced through the overlap effect between the conical dipole and the coupling patch. The double-layer coupling patch can increase the capacitance, cancel the inductive components of port one and port two, and reduce the resonant frequency of the dipole. The capacitive components between adjacent elements of the tightly coupled array antenna can also cancel the strong inductive effect brought by the ground plane. At this time, the array impedance changes gradually. Therefore, the tightly coupled array can extend the impedance bandwidth while facilitating impedance matching, thereby achieving impedance matching with the ultra-wideband tightly coupled antenna.

[0041] To enhance forward radiation capability, a conical dipole was chosen for the radiating patch. Since the antenna's radiation impedance changes less rapidly with angle in the E-plane than during phase scanning in the H-plane, the impedance change is more drastic during H-plane phase scanning, thus having a greater impact on the array's impedance bandwidth performance. Therefore, adding a wide-angle matching layer slows down the impedance change rate during phase scanning compared to when it changes directly in air. Thus, a vertically placed frequency-selective surface patch was added to the antenna element to act as a wide-angle matching layer, achieving both wide-angle scanning and a lightweight design. Furthermore, two rectangular patches were designed as directors to improve the antenna's radiation efficiency. A resistive frequency-selective surface was added near ground in the antenna element to eliminate short-circuit resonance points, and this resistive frequency-selective surface achieved more ideal impedance matching, significantly improving the radiation efficiency of the tightly coupled antenna. The average radiation efficiency exceeded 90% during scanning at various angles.

[0042] The technical effects of the present invention are illustrated below through simulation experiments:

[0043] 1. Simulation conditions and content:

[0044] The present invention was simulated using Ansys Electronics Desktop 2022R1 simulation software. Simulation graphs are shown below. Figure 3 In the model, the feed ports of the dual-polarized antenna are port one and port two, respectively.

[0045] 2. Simulation Result Analysis:

[0046] like Figure 6 As shown, the horizontal axis represents frequency and the vertical axis represents standing wave ratio (VSWR). The results show that, under periodic boundary conditions, the phased array antenna element can achieve an operating bandwidth of 1.86–18.64 GHz when scanning at 0°, with an active VSWR of less than 3. When scanning to 45°, the operating bandwidths of one port in the E-plane and H-plane are 1.88–18.7 GHz and 1.87–18.43 GHz, respectively. The VSWR of the other port with dual polarization is 1.84–18.5 GHz and 1.83–18.7 GHz. Therefore, this design can achieve an operating bandwidth of 9 times the frequency.

[0047] like Figure 7 As shown, the horizontal axis represents frequency and the vertical axis represents radiation efficiency. The results show that, under the simulated periodic boundary conditions, the radiation efficiency of the final phased array antenna element is mostly higher than 95%, with the lowest point being higher than 70%, and the average radiation efficiency is greater than 90% in the 2-18 GHz frequency band. Compared with the existing technology, it can maintain a high average radiation efficiency of 90% in a wide frequency band, which exceeds most tightly coupled phased array antenna elements.

[0048] like Figure 8 As shown, the horizontal axis represents frequency, and the vertical axis represents primary polarization and cross-polarization. The results show that the final phased array antenna element has a good cross-polarization ratio under periodic boundary conditions, which is basically below -30dB, and is better than ordinary phased array antennas.

Claims

1. An ultra-wideband phased array antenna element, characterized in that: The antenna unit includes a single-polarized antenna element. Two single-polarized antenna elements are placed crosswise to form a dual-polarized tightly coupled phased array antenna element. The dual-polarized tightly coupled phased array antenna element is placed on an X-shaped groove in the middle of a metal structure (19). The metal structure (19) serves as the floor of the dual-polarized tightly coupled phased array antenna element. A matching third dielectric substrate (18) is covered on top of the metal structure (19). The surface of the third dielectric substrate (18) is embedded with a first resistive frequency selection surface (17) and a second resistive frequency selection surface (16). A copper layer (15) is covered on the second resistive frequency selection surface (16). Finally, a PP sheet (14) is used to bond the third dielectric substrate (18) to the fourth dielectric substrate (13). The second resistive frequency selection surface (16) is a long rectangle with two layers of figure-eight distributed on the upper surface of the third dielectric substrate (18). The first resistive frequency selection surface (17) is located between the inner layers of the second resistive frequency selection surface (16) and is distributed at equal intervals at the four corners.

2. The ultra-wideband phased array antenna element according to claim 1, characterized in that, The single-polarized antenna unit includes a first dielectric substrate (3) and a second dielectric substrate (10) bonded together by inter-dielectric PP sheet (6). A first coupling patch (1) is printed on the upper outer side of the first dielectric substrate (3), and a first balun radiating ground plane (2) is printed on the lower outer side. A second coupling patch (11) is printed on the upper outer side of the second dielectric substrate (10), and a second balun radiating ground plane (12) is printed on the lower outer side. Radiation patches (5) are symmetrically printed on the middle inner side of both the first dielectric substrate (3) and the second dielectric substrate (10). A stripline balun (4) is printed on the lower inner side of the first dielectric substrate (3), and a frequency selective surface patch (8) is printed on the upper inner side of the second dielectric substrate (10). A director radiation patch (9) is provided above the frequency selective surface patch (8).

3. The ultra-wideband phased array antenna element according to claim 2, characterized in that, The inter-use PP sheet (6), the first dielectric substrate (3), and the second dielectric substrate (10) are provided with a plurality of metal vias (7). The metal vias (7) are fed by connecting the first balun radiating ground (2) and the second balun radiating ground (12) to the strip balun (4) respectively.

4. The ultra-wideband phased array antenna element according to claim 2, characterized in that, The radiation patch (5) is a conical dipole patch.

5. The ultra-wideband phased array antenna element according to claim 2, characterized in that, Rectangular director radiation patches (9) are printed between the symmetrically printed radiation patches (5).

6. The ultra-wideband phased array antenna element according to claim 2, characterized in that, The first dielectric substrate (3), the second dielectric substrate (10), the third dielectric substrate (18) and the fourth dielectric substrate (13) are made of Taconic TLY material.

7. The ultra-wideband phased array antenna element according to claim 2, characterized in that, The PP sheet (6) and PP sheet (14) used in the room are made of FR-28-0040-50 material.

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