Ultra-wideband phased-array antenna unit

Abstract

An ultra-wideband phased-array antenna unit comprises single-polarized antenna units, the two single-polarized antenna units are placed in a crossed mode to form a dual-polarization tight-coupling phased-array antenna unit, and the dual-polarization tight-coupling phased-array antenna unit is placed in an X-shaped groove formed in the middle of a metal structural part. The metal structural member is used as a floor of the dual-polarization tight-coupling phased-array antenna unit, a third dielectric plate matched with the metal structural member covers the metal structural member, a first resistive frequency selection surface and a second resistive frequency selection surface are embedded in the surface of the third dielectric plate, a copper layer covers the second resistive frequency selection surface, and a second dielectric plate covers the copper layer. And finally, the third dielectric substrate and the fourth dielectric substrate are bonded by the PP sheet. The introduction of the resistive frequency selective surface greatly widens the working bandwidth of the antenna, and the director can improve the ground radiation efficiency of the antenna; the antenna unit has the working bandwidth of a nine-frequency-multiplication ultra-wide band in practical engineering application, the scanning capability in a large 45-degree range of an E surface and an H surface, excellent port isolation, quite low cross polarization and high-level radiation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications and relates to an ultra-wideband phased array antenna unit, which can be applied to the field of microwave communications. Background Art

[0002] In modern wireless communication systems, antenna technology is widely used in mobile communications as an important component. Phased array antenna is a type of array antenna. It is a high-performance antenna technology that achieves beam steering, scanning and multi-target tracking by controlling the phase of each unit in the antenna array. In traditional phased array antennas, narrower frequency bands are usually used for beam control and signal transmission. However, with the increase in communication needs and spectrum resources, traditional narrowband phased array antennas are gradually unable to meet the needs of modern high-frequency communication systems in high-speed, low-latency, and long-distance communication applications. Therefore, research on ultra-wideband has been a hot topic in recent years. As an emerging technology, ultra-wideband phased array antennas combine the high data transmission rate of ultra-wideband communication with the fast beam adjustment advantages of phased array antennas, providing a solution for high-speed data transmission and fast beam scanning within a wide frequency band. This combination of technologies enables ultra-wideband communication to not only achieve high data rate transmission and low latency, but also flexibly respond to the needs of multi-target detection and tracking in dynamic environments, and also have stronger anti-interference and higher-precision positioning and imaging capabilities. Research on ultra-wideband phased array technology has huge advantages in improving radar and detection capabilities; improving medical imaging technology; promoting autonomous driving and intelligent transportation, and promoting the development of communication technology, etc., which are currently hot research areas. [Zhong J, Johnson A, Alwan EA, et al. Dual-linear polarized 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 unit is a dipole antenna. Although it can achieve a 9:1 working bandwidth, its unit size is 0.48 times 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. Its working bandwidth is wide but its efficiency is only 70%. It can be seen that the research and development of ultra-wideband phased array antenna technology has important theoretical significance and practical application value. Summary of the invention

[0003] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to propose an ultra-wideband phased array antenna, which adopts a tightly coupled design method, broadens the bandwidth by introducing a resistive frequency selective surface, and improves the radiation efficiency by adding a director, thereby successfully achieving an ultra-wideband working bandwidth of 9 times the frequency, and has the advantages of low cost, high radiation efficiency and large working bandwidth.

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

[0005] An ultra-wideband phased array antenna unit includes a single-polarization antenna unit. Two single-polarization antenna units are placed crosswise to form a dual-polarization tightly coupled phased array antenna unit. The dual-polarization tightly coupled phased array antenna unit is placed on an X-shaped groove set in the middle of a metal structure 19. The metal structure 19 serves as the floor of the dual-polarization tightly coupled phased array antenna unit. The metal structure 19 is covered with a matching third dielectric plate 18. The surface of the third dielectric plate 18 is embedded with a first resistive frequency selective surface 17 and a second resistive frequency selective surface 16. The second resistive frequency selective surface 16 is covered with a copper layer 15. Finally, a PP sheet 14 bonds 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 a PP sheet 6. The first dielectric substrate 3 has a first coupling patch 1 printed on the upper outer portion, and a first balun radiation floor 2 printed on the lower portion; the second dielectric substrate 10 has a second coupling patch 11 printed on the upper outer portion, and a second balun radiation floor 12 printed on the lower portion; the first dielectric substrate 3 and the second dielectric substrate 10 have radiation patches 5 printed symmetrically on the inner middle portions, the first dielectric substrate 3 has a stripline balun 4 printed on the inner lower portion, the second dielectric substrate 10 has a frequency selective surface patch 8 printed on the inner upper portion, and a director radiation patch 9 is provided above the frequency selective surface patch 8.

[0007] The inter-PP sheet 6, the first dielectric substrate 3 and the second dielectric substrate 10 are provided with a plurality of metal vias 7, and the metal vias 7 are connected to the first balun radiation floor 2 and the second balun radiation floor 12 respectively through the stripline balun 4 for feeding.

[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 selective surface 16 is in a long rectangular shape, with two inner and outer layers distributed in an "eight" shape on the upper surface of the third dielectric plate 18. The first resistive frequency selective surface 17 is located between the inner layers of the second resistive frequency selective surface 16 and is equidistantly distributed at 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 material of the intermediate PP sheet 6 and the PP sheet 14 is FR-28-0040-50.

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

[0014] The tightly coupled ultra-wideband phased array antenna unit used in the present invention adopts a patch-type frequency selective surface instead of selecting a dielectric layer to increase the thickness, so it has a lower cross-sectional height, and the unit size of the present design is 9 mm, which is 0.54 times the wavelength of the working bandwidth high frequency 18 GHz. The larger unit size can significantly reduce the cost of radar and communication systems.

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

[0016] The present invention adopts a double-layer coupling patch to increase the overlapping area between the coupling patch and the conical dipole, thereby providing stronger capacitive coupling to broaden the working bandwidth of the antenna.

[0017] The present invention utilizes a vertical rectangular frequency selective surface patch to achieve a lightweight design, enhances beam scanning capability, has the ability to scan ±45° on the E-plane and H-plane, and simultaneously improves the resistive frequency selective surface to broaden the working bandwidth.

[0018] In summary, the antenna design of the present invention adopts a double-layer coupled patch structure. The single-polarized antenna unit is composed of two layers of dielectric plates and bonded by a pp layer in the middle. The two polarized antenna units are completely consistent and placed crosswise in the metal structure at the bottom. The metal structure serves as the floor of the entire antenna unit. The upper layer is covered with a resistive frequency selective surface, which can effectively expand the antenna bandwidth. Finally, the simulation results of the antenna unit in the infinite period boundary show that it can achieve 9 times frequency ±45° scanning, with the advantages of low cost, high radiation efficiency, and large working bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0022] Figure 4 It is a schematic structural diagram of the radiation patch 5 and the rectangular director radiation patch 9 of the present invention.

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

[0024] Figure 6 is the standing wave ratio diagram of the antenna unit of the present invention under the periodic boundary, wherein, Figure 6 (a) is the active standing wave ratio of one port, Figure 6 (b) is the active standing wave ratio of the two ports.

[0025] Figure 7 It is a radiation efficiency diagram of the antenna unit of the present invention under the periodic boundary.

[0026] Figure 8 It is a cross-polarization diagram of the antenna unit of the present invention under the periodic boundary. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with 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-polarization antenna unit. Two single-polarization antenna units are placed crosswise to form a dual-polarization tightly coupled phased array antenna unit. The dual-polarization tightly coupled phased array antenna unit is placed on an X-shaped groove set in the middle of a metal structure 19. The metal structure 19 serves as the floor of the dual-polarization tightly coupled phased array antenna unit. The metal structure 19 is covered with a matching third dielectric plate 18. The surface of the third dielectric plate 18 is embedded with a first resistive frequency selective surface 17 and a second resistive frequency selective surface 16. The second resistive frequency selective surface 16 is covered with a copper layer 15. Finally, a PP sheet 14 bonds the third dielectric substrate 18 to the 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 a PP sheet 6. The first dielectric substrate 3 has a first coupling patch 1 printed on the upper outer portion, and a first balun radiation floor 2 printed on the lower portion; the second dielectric substrate 10 has a second coupling patch 11 printed on the upper outer portion, and a second balun radiation floor 12 printed on the lower portion; the first dielectric substrate 3 and the second dielectric substrate 10 have radiation patches 5 printed symmetrically on the inner middle portions, the first dielectric substrate 3 has a stripline balun 4 printed on the inner lower portion, the second dielectric substrate 10 has a frequency selective surface patch 8 printed on the inner upper portion, and a director radiation patch 9 is provided above the frequency selective surface patch 8.

[0030] The inter-PP sheet 6, the first dielectric substrate 3 and the second dielectric substrate 10 are provided with a plurality of metal vias 7, and the metal vias 7 are connected to the first balun radiation floor 2 and the second balun radiation floor 12 respectively through the stripline balun 4 for feeding.

[0031] See also Figure 4 , the radiation patch 5 is a conical dipole patch.

[0032] A rectangular director radiation patch 9 is printed between the symmetrically printed radiation patches 5. The director structure can increase the forward radiation of the antenna, thereby improving the radiation efficiency of the antenna.

[0033] See also Figure 5 The second resistive frequency selective surface 16 is in the shape of a long rectangle, and the inner and outer layers are distributed in an eight-shaped pattern on the upper surface of the third dielectric plate 18. The first resistive frequency selective surface 17 is located between the inner layers of the second resistive frequency selective surface 16 and is equidistantly distributed at the four corners, thereby eliminating common mode resonance in the frequency band and broadening 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 material of the intermediate PP sheet 6 and the PP sheet 14 is FR-28-0040-50.

[0036] The size of the single-polarized antenna unit of the present invention is 9mm×0.608mm×21.25mm. The substrate material of the dipole part is Taconic TLY, with a dielectric constant of 2.2 and a substrate thickness of 0.601mm. Part of it is embedded in the floor. The purpose is to fix the dual-polarized antenna substrate to the metal floor to make its structure more stable. The radiation patch 5 selects the conical dipole form, which has a strong forward radiation capability. The conical dipole is 7.25mm high. The coupling patch is 5.5mm long and 4.75mm wide. The vertical frequency selective surface patch is composed of four rectangular patches, each with a size of 1.775mm×1.8mm. The director is composed of two rectangular patches, which are 2mm×0.5mm and 1mm×0.5mm respectively, which can improve the radiation efficiency of the antenna. The feed balun is composed of the first balun radiation floor 2, the second balun radiation floor 12 and the stripline balun 4 to achieve broadband impedance transformation.

[0037] like Figure 3As shown, the dual-polarized antenna is composed of two crossed single-polarized antennas, so the size of a single antenna unit is 9mm×9mm×21.25mm. The two polarized coupling patches need to be electrically connected by soldering. The size of the metal structure is 9mm×9mm×4mm and a hollow design is made in the middle to facilitate the insertion of the dual-polarized antenna and welding with the SSMP connector. The size of the third dielectric plate 18 and the fourth dielectric plate 13 is 7.2mm×7.2mm, the resistive frequency selective surface 16 is composed of four rectangular resistor films, each with a size of 4.2mm×0.8mm, and the resistive frequency selective surface 17 is composed of four square resistor films, each with a size of 0.9mm×0.9mm. The resistive FSS substrate material is Taconic TLE (cloth-coated planar resistor film and planar laminate material), with a dielectric constant of 2.95. The specification of the resistive frequency selective surface is 50Ω / sq.

[0038] In order to make the dual-polarized tightly coupled antenna strip line work properly, Figure 1 As shown in the figure, make as many metalized vias as possible near the stripline balun to connect the upper and lower metal floors of the stripline dielectric layer. The radius of the metalized via is 0.125mm. Similarly, the double-layer conical dipole radiation patch and the double-layer coupling patch also need to be connected through metalized vias.

[0039] Working principle of the present invention:

[0040] The 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 overlapping effect between the conical dipole and the coupling patch. This coupling enhances the capacitive coupling effect between the elements, so that each antenna unit not only has electromagnetic interaction with the surrounding units, but also its radiation characteristics and performance will be affected by the adjacent units, thereby improving the performance characteristics of beam forming, bandwidth, gain and interference suppression. Its working principle is to introduce coupling capacitance through the overlapping effect between the conical dipole and the coupling patch. The double-layer coupling patch can increase the capacitance, offset the inductance component of port one and port two, and reduce the resonant frequency of the dipole. The capacitance component between adjacent array elements of the tightly coupled array antenna can also offset the strong inductance effect brought by the floor, and the array impedance changes smoothly at this time. Therefore, the tightly coupled array can expand the impedance bandwidth on the basis of being conducive to impedance matching, thereby achieving impedance matching with the ultra-wideband tightly coupled antenna.

[0041] For the radiation patch, a conical dipole is selected to increase the forward radiation capability. Since the speed at which the radiation impedance of the antenna changes with angle on the E plane is not as fast as that of the H plane phase scan, that is, the impedance change of the array will be more drastic when the array is phase scanned on the H plane, which will have a greater impact on the array impedance bandwidth performance. Therefore, after the array is loaded with a wide-angle matching layer, the change speed of the array impedance during phase scanning will be slower than the change speed directly in the air. Therefore, a vertical frequency selective surface patch is loaded in the antenna unit to act as a wide-angle matching layer to achieve a lightweight design while realizing wide-angle scanning. In addition, two rectangular patches are designed as directors to improve the radiation efficiency of the antenna. A resistive frequency selective surface is loaded near the ground in the antenna unit to eliminate the short-circuit resonance point of the antenna, and a more ideal impedance matching is achieved through the resistive frequency selective surface, which improves the radiation efficiency of the tightly coupled antenna. The antenna has an average radiation efficiency of more than 90% when scanning at various angles.

[0042] The following simulation experiments are used to illustrate the technical effects of the present invention:

[0043] 1. Simulation conditions and contents:

[0044] The full-wave simulation of the present invention is performed using Ansys Electronics Desktop 2022R1 simulation software. Figure 3 In the model, the feeding ports of the dual-polarized antenna are port 1 and port 2 respectively.

[0045] 2. Analysis of simulation results:

[0046] like Figure 6 As shown, the horizontal axis is frequency and the vertical axis is standing wave ratio. The results show that the final phased array antenna unit is simulated under periodic boundary conditions. When the active standing wave is less than 3, the antenna can achieve an operating bandwidth of 1.86-18.64 GHz when scanning 0°. When scanning to 45°, the operating bandwidth of one port on the E plane and H plane are 1.88-18.7 GHz and 1.87-18.43 GHz respectively. The standing wave performance of the other dual-polarized port is 1.84-18.5 GHz and 1.83-18.7 GH. Therefore, this design can achieve a 9-fold operating bandwidth.

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

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

Claims

1. An ultra-wideband phased array antenna unit, characterized in that: The invention comprises 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 arranged 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 unit, a third dielectric plate (18) matching with the metal structure (19) is covered above, a first resistive frequency selective surface (17) and a second resistive frequency selective surface (16) are embedded on the surface of the third dielectric plate (18), a copper layer (15) is covered on the second resistive frequency selective surface (16), and finally a PP sheet (14) is used to bond the third dielectric substrate (18) to the fourth dielectric substrate (13).

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

3. The ultra-wideband phased array antenna unit according to claim 2, characterized in that: A plurality of metal vias (7) are provided on the inter-layer PP sheet (6), the first dielectric substrate (3) and the second dielectric substrate (10), and the metal vias (7) are respectively connected to the first balun radiation floor (2) and the second balun radiation floor (12) through the stripline balun (4) for power feeding.

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

5. The ultra-wideband phased array antenna unit according to claim 1, characterized in that: A rectangular director radiation patch (9) is printed between the symmetrically printed radiation patches (5).

6. The ultra-wideband phased array antenna unit according to claim 1, characterized in that: The second resistive frequency selective surface (16) is in the form of a long rectangular strip, and the inner and outer layers are distributed in an "eight" shape on the upper surface of the third dielectric plate (18); the first resistive frequency selective surface (17) is located between the inner layers of the second resistive frequency selective surface (16) and is distributed equidistantly at the four corners.

7. The ultra-wideband phased array antenna unit 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.

8. The ultra-wideband phased array antenna unit according to claim 2, characterized in that: The intermediate PP sheet (6) and the PP sheet (14) are made of FR-28-0040-50.

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