Broadband / high gain / high isolation / low cross polarization dual-polarized antenna for millimeter wave communication

Abstract

The invention discloses a broadband / high gain / high isolation / low cross polarization dual polarized antenna for millimeter wave communication. The antenna is formed by combining and fastening three layers of dielectric plates through screws, and double surfaces of each layer of dielectric plate are coated with copper. From top to bottom, the first dielectric plate is provided with a square substrate integrated cavity (SIC) enclosed by metal through holes, a first metal layer is etched along the range of the SIC to form an open aperture for antenna radiation, and meanwhile, a windmill type metal patch is loaded at the central position of the aperture surface to maintain an internal electric field of the SIC to be in a TM mode in a working frequency band; the symmetrical structure provides a dual-polarization radiation condition. And meanwhile, the SIW feed transmission lines are orthogonally arranged, so that the requirement of high isolation between the two input ports can be met.

Description

Technical Field

[0001] This invention relates to a wideband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication, belonging to the field of wireless communication technology. Background Technology

[0002] Currently, due to the rapid development of fifth-generation / sixth-generation wireless communication technologies, the spectrum below Sub-6 GHz has become severely redundant, making it even more difficult to meet the demands for high data rates. Meanwhile, dual-polarized antennas, because they can radiate in two azimuth planes, can effectively improve the channel capacity of communication systems and, to some extent, reduce signal attenuation caused by multipath effects. In this context, dual-polarized antennas operating in the millimeter-wave (MMW) band are particularly important due to their wide bandwidth, strong anti-interference capabilities, and ability to improve channel capacity.

[0003] In dual-polarized antenna design, patch antennas [1], [2], waveguide antennas [3], and magnetoelectric dipole antennas (MEdipole) [4], [5] are often more popular due to their simple structure, ease of fabrication, and low cost. Reference [1] reports a compact dual-polarized tandem array, which benefits from the low profile and simple structure of the patch antenna. Similarly, due to the good symmetry of the ME dipole antenna structure, the dual-polarized antennas proposed in [4] and [5] have similar radiation characteristics under both polarizations, with a working bandwidth greater than 40%. However, there are still some shortcomings of current dual-polarized antennas in the millimeter-wave band. First, the operating frequency bands of the dual-polarized antennas mentioned above are mostly in the Ka band and below, with few reports on broadband dual-polarized antennas for the Q band, V band, or even higher frequencies. Second, it is well known that high gain and wide bandwidth are difficult to achieve simultaneously, especially for dual-polarized antennas sharing a common radiating aperture. Furthermore, dual-polarized antennas have two ports, and achieving high isolation between these ports is particularly important for multi-port devices. Moreover, for dual-polarized antennas, the cross-polarization level is a key indicator of performance; a lower cross-polarization level means better polarization purity and less susceptibility to channel interference. In the reported literature, the cross-polarization level currently achieved at the antenna element level is mostly only around -20dB or even worse. Against this backdrop, proposing a dual-polarized antenna that can be extended to high-frequency millimeter waves and possesses broadband, high gain, high isolation, and low cross-polarization is of significant value.

[0004] [1]G.F.Hamberger,S.Trummer,U.Siart,and T.F.Eibert,“Aplanar dual-polarized microstrip 1-D-beamforming antenna array for the 24-GHz band,”inIEEE Transactions on Antennas and Propagation,vol.65,no.1,pp.142-149,Jan.2017.

[0005] [2]Y.Fan and Y.Dong,“Awideband and high gain dual-polarized basestation antenna with parasitic patch,”2023IEEE International Symposium onAntennas and Propagation and USNC-URSI Radio Science Meeting,Portland,OR,USA,2023,pp.1739-1740.

[0006] [3]M.Ferrando-Rocher,J.I.Herranz-Herruzo,A.Valero-Nogueira,B.Bernardo-Clemente,A.U.Zaman,and J.Yang,“8×8Ka-band dual-polarized arrayantenna based on gap waveguide technology,”in IEEE Transactions on Antennasand Propagation,vol.67,no.7,pp.4579-4588,July2019.

[0007] [4]Y.Li,C.Wang,and Y.X.Guo,“A Ka-band wideband dual-polarizedmagnetoelectric dipole antenna array on LTCC,”in IEEE Transactions onAntennas and Propagation,vol.68,no.6,pp.4985-4990,June 2020.

[0008] [5] Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a broadband, high-gain, high-isolation, low-cross-polarization dual-polarized antenna for millimeter-wave communication. It includes an open-aperture cavity-backed radiator with a symmetrical structure, a vertically polarized SIW transmission line along the x-axis, and a horizontally polarized SIW transmission line along the y-axis. The radiator and transmission lines are respectively located on a three-layer dielectric substrate and fixed together with M1 screws to form the dual-polarized antenna.

[0010] The three-layer dielectric substrate is arranged from top to bottom as dielectric substrate 1, dielectric substrate 2, and dielectric substrate 3. Each dielectric substrate has double-sided metallization, and the six metal layers are arranged from top to bottom as metal layer 1, metal layer 2, metal layer 3, metal layer 4, metal layer 5, and metal layer 6.

[0011] Within the cavity formed by the metal vias on metal layer 1, a square area is etched away to create an open aperture. A windmill-shaped patch is loaded at the center of the open aperture.

[0012] On dielectric substrate 1, there is a square substrate integration cavity surrounded by metal through holes;

[0013] At the center of metal layer 2 and metal layer 3, cross-shaped slits of the same size are etched.

[0014] On dielectric substrate 2, there is a SIW power supply structure surrounded by metal through holes, which corresponds to port 1;

[0015] At the center of metal layer 4 and metal layer 5, gaps of the same size are etched.

[0016] On dielectric substrate 3, there is a SIW power supply structure surrounded by metal through holes, which corresponds to port 2;

[0017] The center position of the open aperture and the windmill-shaped patch coincides with the center position of the xoy coordinate axis, and is axially symmetrical with respect to both the x-axis and y-axis, to ensure that the radiation characteristics of different polarizations are as similar as possible.

[0018] To prevent electromagnetic wave leakage, the metal vias on the dielectric layer 1 have a diameter of 0.5 mm and a geometric center spacing of less than 0.125λ between adjacent vias, where λ is the free space wavelength at the center frequency.

[0019] The center position of each cross slit coincides with the center position of the xoy coordinate axis;

[0020] Each of the cross-shaped gaps is composed of two orthogonal rectangular gaps;

[0021] The center position of each gap coincides with the center position of the xoy coordinate axis;

[0022] Each of the aforementioned gaps is a rectangular structure;

[0023] In order to prevent electromagnetic wave leakage, the SIW feeding structure on the dielectric substrate 2 has a via diameter of 0.05λ and a geometric center spacing of 0.075λ-0.125λ between adjacent vias, where λ is the free space wavelength at the center frequency.

[0024] In order to prevent electromagnetic wave leakage, the SIW feeding structure on the dielectric substrate 3 has a via diameter of 0.05λ and a geometric center spacing of 0.075λ-0.125λ between adjacent vias, where λ is the free space wavelength at the center frequency.

[0025] The polarization forms of the dual-polarized antenna include: vertical linear polarization and horizontal linear polarization;

[0026] The feed port 1 is connected to the WR22 wave converter and is used as a vertically polarized radiation feed port;

[0027] The feed port 2 is connected to the WR22 wave converter and is used as a horizontally polarized radiation feed port;

[0028] The electromagnetic wave within the SIW transmission line of the dual-polarized antenna substrate is TE. 10 model;

[0029] The dual-polarized antenna operates in TM mode inside the substrate integrated cavity when vertically polarized. 211 The operating mode inside the substrate integrated cavity during horizontal polarization is TM. 121 model;

[0030] The dual-polarized antenna of the present invention can be extended to any millimeter-wave frequency band as needed and can be installed in various locations of a millimeter-wave communication system.

[0031] The present invention has the following outstanding advantages:

[0032] (1) This invention discloses a broadband high-gain substrate integrated cavity antenna fed by slot coupling. The antenna adopts a full SIW structure and can be extended to other millimeter wave frequency bands as needed.

[0033] (2) By loading a windmill-shaped metal sheet at the center of the open aperture, TM is achieved inside the cavity. 211 / TM 121 The high-order mode achieves a high gain of 11.8 dBi while maintaining an overlap impedance bandwidth of more than 27.5%, solving the problem of simultaneously achieving high gain and wide bandwidth in high-frequency millimeter-wave dual-polarized antennas.

[0034] (3) By placing SIW feeding structures with different polarizations on different layers of dielectric substrates, the electromagnetic wave transmission directions in the feeding structures under the two polarizations are orthogonal to each other, which greatly improves the isolation between the two ports and achieves an isolation of more than 44dB.

[0035] (4) By utilizing the higher-order modes of the substrate integrated cavity, not only are the broadband high-gain characteristics of the dual-polarized antenna realized, but it also has a cross-polarization level of less than -25dB in the operating frequency band, thus achieving low cross-polarization.

[0036] (5) It is fabricated on a dielectric substrate, has a simple structure, is easy to process, and can be mass-produced at low cost through PCB technology. It is a planar side-firing antenna with a low profile and small size, and can be integrated into various terminal communication systems. Attached Figure Description

[0037] Figure 1 This is a three-dimensional structural diagram of the side-firing millimeter-wave dual-polarized planar antenna of the present invention;

[0038] In the figure, (1) is a windmill patch, (2) is a metal through hole, (3) is a substrate integrated cavity, (4) and (10) are cross-shaped slots, (5) is port 1, (6) and (14) are slots, (7) is metal layer 1, (8) is dielectric substrate 1, (9) is metal layer 2, (11) is metal layer 3, (12) is dielectric substrate 2, (13) is metal layer 4, (15) is metal layer 5, (16) is dielectric substrate 3, (17) is metal layer 6, and (18) is port 2.

[0039] Figure 2 This is a schematic diagram of the internal electric field modes of the radiator under different polarization conditions according to the present invention;

[0040] Figure 3 This is a top view of the structure of the dielectric plate 1 in this invention;

[0041] Figure 4 This is a top view of the structure of the dielectric plate 2 in this invention;

[0042] Figure 5 This is a top view of the structure of the dielectric plate 3 in this invention;

[0043] Figure 6 These are the simulation results of the S-parameters and gain curve of the side-fire dual-polarized antenna of this invention;

[0044] Figure 7 These are simulation results of the E-plane and H-plane radiation patterns of the side-fired dual-polarized antenna of this invention at 32GHz, 36GHz, and 40GHz. Detailed Implementation

[0045] To make the features, technical solutions, objectives, and advantages of the embodiments of the present invention clearer, the technical solutions and implementation methods of the embodiments of the present invention will be clearly, completely, and meticulously described below with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] The present invention will be further illustrated below through specific embodiments and in conjunction with the accompanying drawings.

[0047] like Figure 1 As shown, this invention is a side-fire planar on-board dual-polarized antenna for the millimeter-wave band. It includes a back-cavity antenna element based on a substrate integrated cavity and two layered orthogonally placed substrate integrated waveguide feed structures. The dual-polarized antenna is assembled from three layers of dielectric substrates with double-sided metal coatings using M1 screws. The back-cavity antenna based on the substrate integrated cavity is integrated on dielectric substrate 1, the substrate integrated waveguide feed structure that excites vertical linear polarization is integrated on dielectric substrate 2, and the substrate integrated waveguide feed structure that excites horizontal linear polarization is integrated on dielectric substrate 3.

[0048] Figure 2 This is a top view of dielectric substrate 1 where the antenna radiator is located. The centers of the windmill-shaped patch, the square substrate integrated cavity, the square open aperture, and the cross-shaped slot all coincide with the center of the dielectric substrate. The windmill-shaped patch, located at the center of the open aperture, acts as an electric wall, suppressing the electric field at the center of the cavity, resulting in the dominant electric field mode within the cavity being TM. 211 Model or TM 121The parameters of dielectric substrate 1 are as follows: L = 10 mm, cl = 6.8 mm, pl = 1.85 mm, sl = 0.675 mm, sw = 0.2 mm. There are no strict requirements on the number of metal pillars on each side and the geometric center spacing of the pillars forming the substrate integration cavity, as long as the condition of no electromagnetic wave leakage is met. Here, the number of metal vias on each side is 10, and the geometric center spacing between adjacent vias is 0.756 mm. The material of dielectric substrate 1 is Rogers 5880, and the thickness is 1.575 mm.

[0049] Figure 3 This describes the operating mode inside the integrated cavity of the antenna radiator substrate. It can be seen that under the influence of the windmill patch, when excited at port 1, TM... 211 The mode dominates; when TM is stimulated at port 2, 121 Patterns dominate.

[0050] Figure 4 This is a top view of dielectric substrate 2, where the vertically polarized SIW feed structure of the antenna is located. The geometric centers of the cross-shaped slot and the rectangular feed cavity coincide with the center of the dielectric substrate. The parameters of dielectric substrate 2 are as follows: L = 10 mm, f1 = 6.8 mm, f2 = 3.1 mm, l1 = 3.2 mm, w1 = 0.6 mm, l2 = 3 mm, w2 = 0.6 mm, ws = 4 mm. The material of dielectric substrate 2 is Rogers 5880, and the thickness is 1.575 mm.

[0051] Figure 5 This is a top view of dielectric substrate 3, where the horizontally polarized SIW feed structure of the antenna is located. The geometric centers of the slots and the rectangular feed cavity coincide with the center of the dielectric substrate. The parameters of dielectric substrate 3 are: L = 10 mm, f3 = 3 mm, f4 = 6 mm, l3 = 2.7 mm, w3 = 0.4 mm, ws = 4 mm. The dielectric substrate 3 is made of Rogers 5880 material and has a thickness of 1.575 mm.

[0052] There are no strict requirements on the number of metal vias and the geometric center spacing between adjacent vias in the SIW feed structure, as long as the condition of no electromagnetic wave leakage is met. In this embodiment, the diameter of the metal vias on dielectric substrates 2 and 3 is 0.4 mm, and the geometric spacing ranges from 0.075λ to 0.125λ, where λ is the free space wavelength at the center frequency.

[0053] The feed port width ws on dielectric substrates 2 and 3 is 4mm, ensuring that TE is within the operating frequency band of this embodiment. 10 The model is the primary model.

[0054] The antenna is assembled using a multilayer dielectric substrate. Therefore, the geometric dimensions, etching gap dimensions, and positions of the metal layer 2 on the lower surface of dielectric substrate 1 and the metal layer 3 on the upper surface of dielectric substrate 2, as well as the metal layer 4 on the lower surface of dielectric substrate 2 and the metal layer 5 on the upper surface of dielectric substrate 3, are completely identical.

[0055] All dielectric substrates are coated with metal layers on both sides, and the thickness of each metal layer is 0.036 mm.

[0056] To achieve both vertical and horizontal polarization, the dual-polarized antenna is fed through port 1 and port 2 respectively.

[0057] Figure 6 The simulated S-parameters and gain curves for this embodiment are shown. The simulation results show that port 1 has an impedance bandwidth of 31.4% (31.78-43.62GHz) and a maximum gain of 11.85dBi; port 2 has an impedance bandwidth of 27.5% (31.78-41.93GHz) and a maximum gain of 11.27dBi; the antenna impedance overlap bandwidth is 27.5% (31.78-41.93GHz); and the isolation of the two ports is greater than 44dB throughout the entire operating frequency band.

[0058] Figure 7 The simulated radiation patterns of the E-plane and H-plane of this embodiment at 32 GHz, 36 GHz, and 40 GHz, respectively. The simulation results show that the antenna exhibits good directivity along the z-axis under both polarizations, and the cross-polarization reaches below -25 dB. Because the radiating elements have high symmetry, the radiation patterns of the two polarizations are essentially identical, ensuring the similarity of the dual-polarization radiation characteristics.

Claims

1. A broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication, characterized in that, It includes a three-layer dielectric substrate, each of which is double-sided copper-clad as a metal layer. From the top to the bottom, the three-layer dielectric substrate is defined as dielectric substrate 1, dielectric substrate 2, and dielectric substrate 3; the six metal layers are defined as metal layer 1, metal layer 2, metal layer 3, metal layer 4, metal layer 5, and metal layer 6. The resonant mode of the dual-polarized antenna unit is formed inside the rectangular substrate integrated cavity (3) surrounded by metal through-holes (2) and fed through orthogonally placed SIW transmission lines; The energy of the dual-polarized antenna element is radiated into free space through an open aperture inside a rectangular outline etched in a metal through-hole (2); A windmill-shaped rectangular patch (1) is loaded in the center of the radiation aperture of the dual-polarized antenna unit. The structure of the rectangular patch is symmetrical with respect to the x-axis and y-axis, which ensures that the dual-polarized radiation characteristics are similar. The two polarization modes of the dual-polarized antenna element are excited respectively via transmission lines located on dielectric substrate 2 (12) and dielectric substrate 3 (16); The vertical linear polarization (V-pol) of the dual-polarized antenna unit is excited by the SIW transmission line on the dielectric substrate 2 (12). The SIW structure is a closed structure consisting of metal vias on the dielectric substrate and metal layers 3 (11) and 4 (13). The energy fed in by port 1 (5) is transmitted through the SIW transmission line and then coupled to the interior of the substrate integrated cavity (3) on the dielectric substrate 1 (8) through the cross-shaped slots (4) etched on metal layer 3 (11) and the cross-shaped slots (10) etched on metal layer 2 (9). Port 1 (5) is connected to the WR22 millimeter-wave adapter. The horizontal polarization (H-pol) of the dual-polarized antenna unit is excited by the SIW transmission line on the dielectric substrate 3 (16). The SIW structure is a closed structure consisting of metal vias on the dielectric substrate and metal layers 5 (15) and 6 (17). The energy fed in by port 2 (18) is transmitted through the SIW transmission line and then coupled to the substrate integrated cavity (3) located on the dielectric substrate 1 (8) via the etched slots (6) on metal layer 5 (15), the etched slots (14) on metal layer 4 (13), the etched cross slots (4) on metal layer 3 (11) and the etched cross slots (10) on metal layer 2 (9). Port 2 (18) is connected to the WR22 millimeter-wave adapter.

2. The broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication according to claim 1, characterized in that: The windmill patch (1) and the substrate integrated cavity (3) both have symmetrical structures relative to the x-axis and y-axis.

3. A broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication according to claim 1, characterized in that: The etched gaps on adjacent dielectric sheets, such as cross gaps (10) and cross gaps (4), gaps (14) and gaps (6), all have the same size.

4. A broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication according to claim 1, characterized in that: The SIW transmission lines located on media board 2 (12) and media board 3 (16) are placed orthogonally to ensure high isolation between ports.

5. A broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication according to claim 1, characterized in that: It features wide bandwidth, high gain, high isolation, and low cross-polarization radiation characteristics, and can be integrated into millimeter-wave communication systems.

6. A broadband / high-gain / high-isolation / low-cross-polarization dual-polarized antenna for millimeter-wave communication according to claim 1, characterized in that: The dual-polarized antenna operates in TM modes when fed from different ports. 211 Model and TM 121 mold.

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