Compact dual-polarization millimeter wave multi-beam antenna array

Abstract

The invention relates to the field of millimeter wave dual-polarized multi-beam antenna arrays, and particularly discloses a compact dual-polarized millimeter wave multi-beam antenna array, which comprises a transition structure, a dual-mode Butler matrix and a dual-polarized antenna, the input end of the transition structure is connected with the radio frequency interface, and the output end is connected with the input end of the dual-mode Butler matrix; the output end of the dual-mode Butler matrix is connected with the input end of the dual-polarized antenna; compared with the traditional discrete design, the high integration level and miniaturization significantly reduce the physical size of the antenna array, the coverage range of the antenna array is expanded, a single array can replace multiple sets of narrow beam antennas, and the number of devices is reduced; spatial multiplexing gain is achieved, multi-user parallel communication or multi-path transmission is supported, and the system capacity and the spectrum efficiency are improved; the dual polarization performance is improved, the polarization multiplexing gain is increased, independent data streams are transmitted through two orthogonal polarization channels under the same time-frequency resource, and the spectrum efficiency can be theoretically improved by two times.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave dual-polarized multibeam antenna arrays, and more specifically to a compact dual-polarized millimeter-wave multibeam antenna array. Background Technology

[0002] The evolution of mobile communication technology towards 5G and future 6G is driving a rapid increase in wireless data transmission rates and system capacity. Millimeter wave bands, with their abundant available spectrum resources, have become a key technology choice for achieving ultra-high-speed communication. However, millimeter wave signals suffer from significant path loss, penetration loss, and susceptibility to obstruction during propagation. To effectively overcome these physical limitations and establish reliable communication links, employing high-gain directional beams has become a necessary means for millimeter wave systems.

[0003] While a single high-gain beam can improve link quality, it is insufficient to meet the comprehensive requirements of modern wireless communication systems for wide-area coverage, multi-user concurrent access, high-speed mobility support, and anti-interference capabilities. In densely populated user scenarios (such as large stadiums and transportation hubs) or scenarios requiring simultaneous service to multiple mobile terminals, the system needs the ability to generate and manage multiple independent and controllable spatial beams. Multi-beam antenna arrays have thus evolved, capable of generating multiple beams pointing in different spatial directions simultaneously within the same frequency band, achieving spatial multiplexing. This technology significantly improves the system's user capacity and spectral efficiency, effectively supports high-speed mobile users through rapid beam switching and tracking (beam management), and utilizes spatial degrees of freedom for interference suppression or coordination.

[0004] To further enhance system performance within limited physical space and spectrum resources, dual-polarization technology has been integrated into the design of millimeter-wave multi-beam antenna arrays. Dual-polarized antenna arrays can radiate or receive electromagnetic waves with two orthogonal polarizations (such as vertical / horizontal polarization or ±45° slant polarization) on the same physical aperture. Utilizing the low correlation between the two orthogonal polarized channels improves the system's robustness in multipath fading environments (polarization diversity gain). More importantly, this technology allows for the independent transmission of two data streams on the same time-frequency resources (polarization multiplexing), theoretically doubling spectral efficiency and forming a key foundation for multiple-input multiple-output (MIMO) technology. Summary of the Invention

[0005] The purpose of this invention is to provide a compact dual-polarized millimeter-wave multi-beam antenna array to solve the problems mentioned in the background art, and to solve the problem that traditional dual-polarized multi-beam antenna arrays are difficult to achieve high-density integration in the millimeter-wave band due to their large physical size and complex feeding network. It also addresses the technical challenge of how to generate multiple (4) independent and controllable beams simultaneously on a millimeter-wave miniaturized platform, solves the problem of limited coverage of a single beam, and improves channel capacity by utilizing dual polarization.

[0006] To achieve the above objectives, the present invention provides a compact dual-polarized millimeter-wave multi-beam antenna array comprising:

[0007] It includes a transition structure, a dual-mode Butler matrix, and a dual-polarized antenna; the input end of the transition structure is connected to an RF interface, and the output end is connected to the input end of the dual-mode Butler matrix; the output end of the dual-mode Butler matrix is ​​connected to the input end of the dual-polarized antenna.

[0008] The transition structure is used to connect to the radio frequency port. The dual-mode Butler matrix can simultaneously generate two orthogonal mode excitations, namely TEM mode and TE mode. 10 Mode. Dual-polarized antenna, with two modes to excite different types of antennas, implemented through X-polarized and Y-polarized radiation structures.

[0009] A Butler matrix is ​​an integrated radio frequency network used for beamforming and beam control, widely used in antenna array systems, especially in phased array antennas. A Butler matrix is ​​a multi-port network, typically composed of a set of fixed phase shifters and power dividers. Its basic function is to output signals with appropriate phase and amplitude according to the different directions of the input signal, thereby forming beams in different directions.

[0010] The dual-mode Butler matrix includes four input ports and four output ports. Between the first input port, the second input port, and the first and second output ports, a dual-mode directional coupler, a dual-mode phase shifter a, a dual-mode directional coupler, and a dual-mode phase shifter b are sequentially arranged. The structure between the third and fourth input ports and the third and fourth output ports is consistent with the structure between the first and second input ports and the first and second output ports. The outputs of the two dual-mode phase shifters b constitute the first and fourth output ports of the dual-mode Butler matrix. A dual-mode cross-coupler is provided between the two dual-mode phase shifters a and the two dual-mode phase shifters b. The output of the dual-mode cross-coupler between the two dual-mode phase shifters b constitutes the second and third output ports of the dual-mode Butler matrix. The four input ports and four output ports can switch between TEM mode and TE mode. 10 The dual-mode Butler matrix enables independent beam control for two polarization signals. Its dimensions are 2.6λ × 7.7λ × 0.0525λ. Compared to a traditional 4×4 Butler matrix, the dual-mode Butler has a similar cross-sectional size.

[0011] A directional coupler is a four-port network that enables controlled distribution of radio frequency signals. Through a coupling mechanism, it distributes input power to the through port and the coupled port in a predetermined ratio, while ensuring high directivity and low insertion loss. The directional coupler is one of the key components of a BM (Microcontroller Unit), enabling uniform power output and a 90° phase difference output.

[0012] The dual-mode directional coupler is a fusion of a traditional SIW-based directional coupler and a branch-line directional coupler. The traditional SIW-based directional coupler is constructed by placing two rows of SIWs side-by-side and then removing a portion of the common first metal via, creating a structure capable of simultaneously transmitting TE signals. 10 and TE 20 The coupling region of the mode is the substrate integrated waveguide coupling region. The branch line consists of a main line, a secondary line, and two coupled branch striplines (branch line a and branch line b), and its transmission mode is a single TEM mode, i.e., the branch line coupling region.

[0013] The dual-mode directional coupler is formed by coupling two dual-mode substrate integrated coaxial transmission lines, and a coupling region is provided in the coupling area of ​​the two dual-mode substrate integrated coaxial transmission lines.

[0014] The coupling region includes a substrate integrated waveguide coupling region; the substrate integrated waveguide coupling region includes two second metal vias and a first rectangular coupling slot disposed between the second metal vias; a branch line coupling region is provided on the first rectangular coupling slot; the branch line coupling region includes two branch lines a and b; the branch lines a and b form a "well" shaped structure; a second rectangular coupling slot is provided at the center of the "well" shaped structure; the branch line b is disposed on the metal strips of two dual-mode substrate integrated coaxial transmission lines; the two ends of the branch line a form second rectangular protrusions on the branch line b; a first rectangular protrusion is provided between the two second rectangular protrusions; and three third rectangular protrusions are equidistantly distributed in the middle of the branch line a.

[0015] Preferably, the admittance of branch line a is 50Ω and the admittance of branch line b is 70.71Ω.

[0016] Preferably, the dual-mode substrate integrated coaxial transmission line (SICL) comprises, from bottom to top, a first metal layer, a first dielectric substrate, an adhesive sheet, a second dielectric substrate, and a second metal layer; a metal strip is disposed between the second dielectric substrate and the adhesive sheet; first metal vias are provided on both sides of the metal strip at equal intervals; the metal vias penetrate the first dielectric substrate, the adhesive sheet, and the second dielectric substrate. The first and second metal layers, as the dual-mode substrate integrated coaxial transmission line (SICL), have the function of confining electromagnetic waves, and the metal strip has the function of guiding TEM mode transmission.

[0017] The dual-mode substrate-integrated coaxial transmission line (SICL) combines the advantages of coaxial lines and planar transmission lines, with TEM mode as its primary mode. Electromagnetic waves in TEM mode exhibit no frequency dispersion and have no cutoff frequency; the bandwidth of TEM mode depends on the cutoff frequency of the first higher-order mode, TE10. Here, the bandwidth of the SICL is widened to construct a dual-mode SICL capable of simultaneously transmitting both TEM and TE10 modes. The cutoff frequency of TE10 mode is approximately 25 GHz, therefore the operating bandwidth of the dual-mode SICL is greater than 25 GHz.

[0018] Preferably, the dual-polarized antenna includes four identical and parallelly arranged dual-polarized antenna elements; each dual-polarized antenna element includes an X-polarized radiation structure and a Y-polarized radiation structure; the X-polarized radiation structure includes a dual-mode substrate-integrated coaxial transmission line and a rectangular slot; the rectangular slot is etched on the second metal layer of the dual-mode substrate-integrated coaxial transmission line; the rectangular slots are staggered on both sides of the metal strip, with a half-wavelength distance between two rectangular slots. The Y-polarized radiation structure includes a lateral coupling slot and a 5×5 metasurface array; the lateral coupling slot is located on the second metal layer, and the metal strip passes through the lateral coupling slot; the 5×5 metasurface array is composed of metasurface units; each metasurface unit includes a rectangular metal patch (25) and an X-shaped slot on the rectangular metal patch; the 5×5 metasurface array has a first metal via around its perimeter. The rectangular slot can cut the current in the X direction, generating X-polarized electromagnetic wave radiation. The Y-polarized radiation structure is generated by TEM waves exciting a transverse slit, which is then coupled to a 5×5 metasurface array via a dielectric to produce Y-polarized electromagnetic wave radiation.

[0019] Preferably, the dual-mode cross-coupler is composed of two dual-mode directional couplers cascaded together.

[0020] Preferably, the dual-mode phase shifter a and dual-mode phase shifter b have the same structure, both including a dual-mode substrate integrated coaxial transmission line and an extension structure disposed on the dual-mode substrate integrated coaxial transmission line; the extension structure includes a bent metal strip and a rectangular hole located inside the bent metal strip; the rectangular hole is disposed on a first metal via on one side of the dual-mode substrate integrated coaxial transmission line; the bends of the bent metal strip are staggered with obtuse angles; the bent metal strip and the rectangular hole are respectively provided with first metal vias on both sides.

[0021] Preferably, the rectangular hole is composed of a first metal via, and both the dual-mode phase shifter a and the dual-mode phase shifter b are coupled to a dual-mode cross-coupler; the length of the rectangular hole can be adjusted by adjusting the distance between the two coupling zones of the dual-mode cross-coupler; the phase shift of the dual-mode phase shifter a and the dual-mode phase shifter b can be changed by adjusting the length of the extension structure; the dual-mode phase shifter a is a 135° / 45° phase shifter, and the dual-mode phase shifter b is a 0° phase shifter.

[0022] Preferably, the branch line b has a length of 6.06 mm and a width of 0.56 mm; the branch line a has a width of 0.47 mm and a length of 6.06 mm; the first rectangular protrusion has a length of 0.55 mm and a width of 0.47 mm; the distance between the first rectangular protrusion and the second rectangular protrusion is 0.42 mm; the third rectangular protrusion has a width of 0.33 mm and a length of 0.84 mm; the distance between two adjacent third rectangular protrusions is 0.68 mm; the first dielectric substrate and the second dielectric substrate are made of the same material, both of which are Rogers 5880, with a thickness of 0.254 mm and a dielectric constant of 2.2; the first metal layer and the second metal layer are made of the same material, both with a thickness of 17.5 μm; the adhesive layer has a thickness of 0.055 mm and a dielectric constant of 2.43.

[0023] Preferably, the transition structure includes ports #1, #2, #3, #4, #5, #6, #7, and #8, all of which are used to connect to external RF ports. Ports #2, #4, #6, and #8 have identical structures, each containing an L-shaped metal strip. One end of the L-shaped metal strip of ports #4, #2, #6, and #8 is sequentially connected to the metal strips of the first, second, third, and fourth input ports of the dual-mode Butler matrix, respectively. 1. Ports #3, #5, and #7 have the same structure, each including an L-shaped first metal via; a first metal via is provided at the bend of the L-shaped metal via; one end of the L-shaped first metal via of ports #3, #1, #5, and #7 is connected sequentially to the first metal via of the first input port, second input port, third input port, and fourth input port of the dual-mode Butler matrix; a third metal via is provided on both sides of ports #1, #2, #3, #4, #5, #6, #7, and #8.

[0024] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0025] Highly integrated and miniaturized, the antenna array employs a dual-mode substrate-integrated coaxial structure, achieving deep integration of dual-polarized radiating elements, multi-beam feed networks, and control circuitry in the millimeter-wave band (26–30 GHz). Compared to traditional discrete designs, this significantly reduces the physical size of the antenna array, solving the assembly precision and space limitations inherent in millimeter-wave systems due to their high frequency and small size. It features multi-beam spatial multiplexing capabilities, simultaneously generating four independent, controllable beams to cover a wide angular area of ​​±60°. Its coverage is expanded: a single array can replace multiple narrow-beam antennas, reducing the number of devices; spatial multiplexing gain supports multi-user parallel communication or multi-path transmission, improving system capacity and spectral efficiency; and dynamic beam management, through rapid beam switching and tracking, enhances adaptability to high-speed mobile users. Dual-polarization performance is improved, and polarization multiplexing gain is increased. Under the same time-frequency resources, independent data streams can be transmitted through two orthogonally polarized channels, theoretically improving spectral efficiency by up to 2 times (basic for MIMO applications). Polarization diversity anti-interference: Utilizing the low correlation between orthogonal polarizations, multipath fading and channel interference are suppressed, significantly improving link stability and robustness. Wideband millimeter-wave operation, with a working bandwidth covering 26–30 GHz (approximately 15.4% of the relative bandwidth), is compatible with 5G NR n258 / n257 bands and future 6G extended bands, meeting the wideband requirements of millimeter-wave communication systems. Simplified structure and enhanced reliability: Integrated power supply network, achieving low-loss, high-isolation power supply through substrate-integrated coaxial cable, avoiding impedance mismatch and phase errors introduced by traditional cable assembly; Optimized thermal stability: The integrated dielectric substrate structure reduces the impact of temperature drift, ensuring consistent electrical performance in the millimeter-wave band. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the dual-mode directional coupler of the present invention, wherein (a) is the substrate integrated waveguide coupling region, and (b) is the branch line coupling region;

[0028] Figure 3 This is a schematic diagram of the dual-mode substrate integrated coaxial transmission line structure of the present invention;

[0029] Figure 4 This is a schematic diagram of the dual-polarized antenna unit structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the dual-mode phase shifter structure of the present invention, wherein (a) is dual-mode phase shifter a and (b) is dual-mode phase shifter b;

[0031] Figure 6 The S-parameters of the dual-mode substrate integrated coaxial line of the present invention;

[0032] Figure 7 This is a schematic diagram of the topological structure of the dual-mode Butler matrix of the present invention;

[0033] Figure 8 This is a diagram showing the electric field distribution in the coupling region of the substrate-integrated waveguide of the present invention.

[0034] Figure 9 This is a diagram showing the electric field distribution in the branch line coupling region of the present invention.

[0035] Figure 10 This is a schematic diagram of the simulation results of the dual-mode directional coupler of the present invention;

[0036] Figure 11 The simulation results of the dual-mode Butler matrix of the present invention are shown, where (a) is the phase difference and phase difference curve of TEM mode excitation, and (b) is the TE... 10 Phase difference and phase curve of mode excitation;

[0037] Figure 12 This is a schematic diagram of the radiation beam of the dual-polarized multi-beam antenna array at 28 GHz of the present invention, where (a) is the X-polarized beam and (b) is the Y-polarized beam.

[0038] As shown in the figure:

[0039] 1 – Transition structure, 2 – Dual-mode Butler matrix, 201 – Dual-mode directional coupler, 202 – Dual-mode phase shifter a, 203 – Dual-mode phase shifter b, 204 – Dual-mode cross coupler, 3 – Dual-polarized antenna, 4 – Branch line coupling region, 5 – Branch line coupling region, 6 – Second metal via, 7 – Metal strip, 8 – First metal via, 9 – First metal layer, 10 – First dielectric substrate, 11 – Adhesive sheet, 12 – Second dielectric substrate, 13 – Second metal layer, 14 – Third metal via, 15 – First rectangular coupling slot, 16 – Branch line b, 17 – Branch line a, 18 – First rectangular protrusion, 19 – 20 - Second rectangular protrusion, 21 - Third rectangular protrusion, 22 - Y-polarized radiation structure, 23 - 5×5 metasurface array, 24 - Metasurface unit, 25 - X-shaped slit, 26 - Rectangular metal patch, 27 - X-polarized radiation structure, 28 - Rectangular groove, 29 - Extended structure, 30 - Bending metal strip, 31 - Rectangular hole, 32 - Lateral coupling slit, 33 - 3dB / 90° directional coupler, 34 - 135° phase shifter, 35 - 0° phase shifter a, 36 - Cross coupler a, 37 - 45° directional coupler, 38 - 0° phase shifter b, 39 - Cross coupler b. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0041] Reference Figure 1-12 As shown, the present invention provides a compact dual-polarized millimeter-wave multi-beam antenna array:

[0042] It includes a transition structure 1, a dual-mode Butler matrix 2, and a dual-polarized antenna 3; the input end of the transition structure 1 is connected to an RF interface, and the output end is connected to the input end of the dual-mode Butler matrix 2; the output end of the dual-mode Butler matrix 2 is connected to the input end of the dual-polarized antenna 3.

[0043] The design process for the dual-mode Butler matrix is ​​as follows:

[0044] S1. The dual-mode directional coupler can be considered as a superposition of two different modes of 4×4 Butler matrices, namely the SIW-based Butler matrix and the branch-line Butler matrix, containing four dual-mode directional couplers, two dual-mode cross-couplers, and four dual-mode phase shifters. The eight output ports correspond to four x-polarized output ports and four y-polarized output ports. Assuming the phase shift of the phase shifters in the 4×4 Butler matrix is ​​φ, let the constant phase differences of the output ports when the excitation input ports #1 to #4 are α1, –α2, α2, and –α1, respectively. Based on the path of the signal in the 4×4 Butler matrix, when the excitation port is #1, the relationship between the phase difference α1 between output ports #5 and #8 and the inherent phase shift of each component is as follows:

[0045]

[0046] In the formula, β is the phase shift difference at the output port of the 3d directional coupler. Let α be the phase difference of the Butler matrix, and α1 be the phase difference between output ports #5 and #8 when the excitation port is #1.

[0047] S2. When the phase shift difference β at the output port of the directional coupler is 90°, two sets of equations can be obtained according to the equations in step S1, namely...

[0048] or

[0049] When the phase shift difference β at the output of the directional coupler is -90°, the solutions to the other two sets of equations can be obtained according to the equations in step S1, namely:

[0050] or

[0051] S3. Similarly, when the excitation port is #2, the relationship between the phase difference α2 between the output ports #5 and #8 and the inherent phase shift of each component is as follows:

[0052]

[0053] S4. When the phase shift difference β at the output port of the directional coupler is 90°, two sets of equations can be obtained according to the equations in step S3, namely...

[0054] or

[0055] When the phase shift difference β at the output of the directional coupler is -90°, the solutions to the other two sets of equations can be obtained according to the equations in step S3, namely:

[0056] or

[0057] Considering the symmetry of the Butler matrix structure, phase analysis for separately exciting ports #3 and #4 is omitted. Common 3dB directional couplers have two output port phase differences: 90° or -90°. Therefore, combining the above steps, there are four possible combinations for constructing a dual-mode Butler matrix. Here, we choose one of the equation solutions to design the dual-mode Butler matrix structure, namely, the phase difference selection for the SIW Butler matrix. Phase difference selection of the branch line Butler matrix

[0058] according to Figure 2 As shown, the dual-mode Butler matrix 2 includes four input ports and four output ports. Between the first input port, the second input port, and the first and second output ports, a dual-mode directional coupler 201, a dual-mode phase shifter a202, a dual-mode directional coupler b203, and a dual-mode phase shifter b203 are sequentially arranged. The structure between the third and fourth input ports and the third and fourth output ports is consistent with the structure between the first and second input ports and the first and second output ports. The outputs of the two dual-mode phase shifters b203 constitute the first and fourth output ports of the dual-mode Butler matrix. A dual-mode cross-coupler 204 is provided between the two dual-mode phase shifters a202 and the two dual-mode phase shifters b203. The output of the dual-mode cross-coupler 204 between the two dual-mode phase shifters b203 constitutes the second and third output ports of the dual-mode Butler matrix 2. The four input ports and four output ports can switch between TEM mode and TE mode.10 The dual-mode Butler matrix enables independent beam control for two polarization signals. The dimensions of the dual-mode Butler matrix are 2.6λ × 7.7λ × 0.0525λ.

[0059] The design flow for the dual-mode directional coupler is as follows:

[0060] The design equations for the S1 and SIW-based directional couplers can be obtained by performing parity-mode analysis. When port #1 is excited, the modes within the coupling cavity can be equivalently represented by the odd-mode TE. 10 Coupled Mode TE 20 Formed by superposition. Due to its symmetry, only the S-parameter matrix when port #1 is excited is given here:

[0061]

[0062] In the formula, S 11 For reflection of port #1, S 21 This indicates a transfer from port #1 to port #2, S 31 This indicates a transfer from port #1 to port #3, S 41 This indicates a transfer from port #1 to port #4, β 10 For TE 10 The phase constant of the mode, β 20 For TE 20 The phase constant of the mode, where K is the wave number and l is the length of the coupling region.

[0063] For SIW-based directional couplers, in order to ensure equal power output and a 90° phase difference output, the transmission field in the coupling region must satisfy equation (1), i.e., (β 10 -β 20 (l / 2) = π / 2, then S exists. 31 =S 41 =0.707. Therefore, a 3dB / 90° directional coupler can be obtained by adjusting the length and width of the coupling region.

[0064] S2. Similarly, the design equations for the branch-line directional coupler can also be obtained through odd-even mode analysis. When port #1 is excited, the modes on the branch lines can be equivalently represented by the superposition of odd and even modes. Due to its symmetry, only the impedance relationships of each branch line when port #1 is excited are given here:

[0065]

[0066] In the formula, G a G is the admittance of branch line a. b Let C be the admittance of branch line b, C be the coupling degree, and the electrical lengths of branch lines a and b be π / 2.

[0067] When there is no reflection at ports #1 and #2, the branch line impedance satisfies the equation For a 3dB / 90° branch-line directional coupler, C = -3dB, then G a / G b =0.707. When the input port Z0 = 50Ω, the admittances of branches a and b are G and G, respectively. a =50Ω, G b = 70.71Ω. Therefore, a 3dB / 90° directional coupler can be obtained by adjusting the impedance of the branch line coupler.

[0068] S3. Combining steps S1 and S2, design a dual-mode directional coupler.

[0069] according to Figure 3 As shown, the dual-mode directional coupler 201 is formed by coupling two dual-mode substrate integrated coaxial transmission lines, and a coupling region is provided in the coupling area of ​​the two dual-mode substrate integrated coaxial transmission lines.

[0070] The coupling region includes a substrate integrated waveguide coupling region 4; the substrate integrated waveguide coupling region 4 includes two second metal vias 6 and a first rectangular coupling slot 15 disposed between the second metal vias 6; a branch line coupling region 5 is provided on the first rectangular coupling slot 15; the branch line coupling region 5 includes two branch lines a17 and b16; the branch lines a17 and b16 form a "well" shaped structure; a second rectangular coupling slot 503 is provided at the center of the "well" shaped structure; the branch line b16 is disposed on the metal strips 7 of two dual-mode substrate integrated coaxial transmission lines; the two ends of the branch line a17 form second rectangular protrusions 19 on the branch line b16; a first rectangular protrusion 18 is provided between the two second rectangular protrusions 19; three third rectangular protrusions 20 are equidistantly distributed in the middle of the branch line a17.

[0071] Specifically, the admittance of branch line a17 is 50Ω, and the admittance of branch line b16 is 70.71Ω.

[0072] according to Figure 4 As shown, the dual-mode substrate integrated coaxial transmission line includes, from bottom to top, a first metal layer 9, a first dielectric substrate 10, an adhesive sheet 1, a second dielectric substrate 12, and a second metal layer 13; the metal strip 7 is disposed between the second dielectric substrate 12 and the adhesive sheet 11; the metal strip 7 has first metal vias 8 evenly distributed on both sides; the metal vias 8 penetrate the first dielectric substrate 10, the adhesive sheet 11, and the second dielectric substrate 12.

[0073] according to Figure 5As shown, the dual-polarized antenna 3 includes four identical and parallelly arranged dual-polarized antenna elements; each dual-polarized antenna element includes an X-polarized radiating structure 26 and a Y-polarized radiating structure 21; the X-polarized radiating structure 26 includes a dual-mode substrate integrated coaxial transmission line and a rectangular slot 27; the rectangular slot 27 is etched on the second metal layer 13 of the dual-mode substrate integrated coaxial transmission line; the rectangular slots 27 are staggered on both sides of the metal strip 7, with a half-wavelength distance between two rectangular slots 27. The Y-polarized radiating structure 21 includes a lateral coupling slot 31 and a 5×5 metasurface array 22; the lateral coupling slot 31 is disposed on the second metal layer 13, and the metal strip 7 passes through the lateral coupling slot 31; the 5×5 metasurface array 22 is composed of metasurface units 23; the metasurface unit 23 includes a rectangular metal patch 25 and an X-shaped slot 24 disposed on the rectangular metal patch 25; the 5×5 metasurface array 22 is provided with a first metal via 8 around its perimeter.

[0074] Specifically, the dual-mode cross-coupler 204 is formed by cascading two dual-mode directional couplers 201.

[0075] Specifically, the dual-mode phase shifter a202 and the dual-mode phase shifter b203 have the same structure, both including a dual-mode substrate integrated coaxial transmission line and an extension structure 28 disposed on the dual-mode substrate integrated coaxial transmission line; the extension structure 28 includes a bent metal strip 29 and a rectangular hole 30 located inside the bent metal strip; the rectangular hole 30 is disposed on a first metal via 8 on one side of the dual-mode substrate integrated coaxial transmission line; the bend of the bent metal strip 29 is chamfered; and first metal vias 8 are respectively provided on both sides of the bent metal strip 29 and the rectangular hole 30.

[0076] Specifically, the rectangular hole 30 is composed of a first metal via 8, and both the dual-mode phase shifter a202 and the dual-mode phase shifter b203 are coupled to the dual-mode cross-coupler 204. The length of the rectangular hole 30 can be adjusted by adjusting the distance between the two coupling zones of the dual-mode cross-coupler 204. The phase shift of the dual-mode phase shifter a202 and the dual-mode phase shifter b203 can be changed by adjusting the length of the extension structure 28. The dual-mode phase shifter a202 is a 135° / 45° phase shifter, and the dual-mode phase shifter b203 is a 0° phase shifter.

[0077] Specifically, the branch line b16 has a length of 6.06 mm and a width of 0.56 mm; the branch line a17 has a width of 0.47 mm and a length of 6.06 mm; the first rectangular protrusion 18 has a length of 0.55 mm and a width of 0.47 mm; the distance between the first rectangular protrusion 18 and the second rectangular protrusion 19 is 0.42 mm; the third rectangular protrusion 20 has a width of 0.33 mm and a length of 0.84 mm; the distance between two adjacent third rectangular protrusions 20 is 0.68 mm; the first dielectric substrate 10 and the second dielectric substrate 12 are made of the same material, both of which are Rogers 5880, with a thickness of 0.254 mm and a dielectric constant of 2.2; the first metal layer 9 and the second metal layer 13 are made of the same material, both with a thickness of 17.5 μm; the adhesive layer 11 has a thickness of 0.055 mm and a dielectric constant of 2.43.

[0078] Specifically, the transition structure 1 includes ports #1, #2, #3, #4, #5, #6, #7, and #8, all of which are used to connect to external RF ports. Ports #2, #4, #6, and #8 have identical structures, each containing an L-shaped metal strip. One end of the L-shaped metal strip of ports #4, #2, #6, and #8 is sequentially connected to the metal strips 7 of the first, second, third, and fourth input ports of the dual-mode Butler matrix 2. 1. Ports #3, #5, and #7 have the same structure, each including an L-shaped first metal via; a first metal via 8 is provided at the bend of the L-shaped metal via; one end of the L-shaped first metal via of ports #3, #1, #5, and #7 is connected sequentially to the first metal via 8 of the first input port, second input port, third input port, and fourth input port of the dual-mode Butler matrix; a third metal via 14 is provided on both sides of ports #1, #2, #3, #4, #5, #6, #7, and #8.

[0079] Dual-mode substrate integrated coaxial (SICL) transmission lines are used to widen the transmission bandwidth, creating a transmission line capable of simultaneously transmitting TEM and TE modes. 10 Dual-mode SICL of the mode Figure 6 Simulation S-parameters for both modes are presented. The cutoff frequency of the TE10 mode is approximately 25 GHz, therefore the operating bandwidth of the dual-mode SICL is greater than 25 GHz.

[0080] Figure 7A block diagram of a dual-mode 4×4 Butler matrix structure is presented, which can be viewed as the superposition of two different modes of 4×4 Butler matrices: the SIW base Butler matrix and the branch-line Butler matrix. Common 3dB directional couplers have two output port phase differences: 90° or -90°. Therefore, there are four possible phase combinations for constructing the dual-mode Butler matrix. Here, one solution to the equation is chosen to design the dual-mode Butler matrix structure, namely, the phase difference selection for the SIW Butler matrix. Phase difference selection of the branch line Butler matrix Table 1 lists the phase differences between different input and output ports.

[0081] Table 1. Phase difference table of output ports

[0082]

[0083] Figure 8 The electric field distribution of the substrate integrated waveguide, specifically the coupling region 5, is shown. When port #1 is excited, the modes within the coupling cavity can be equivalently represented as odd modes TE. 10 Coupled Mode TE 20 Formed by superposition. Figure 9 When port #1 is excited, the electric field distribution of the branch line, i.e. the branch line coupling region 5, can be equivalent to the superposition of odd and even modes.

[0084] Figure 10 Simulation results for the dual-mode directional coupler show that at 28 GHz, the coupler can achieve coupling levels of -3.1 dB and -3.2 dB, respectively. Between 26 GHz and 30 GHz, the peak-to-peak errors of the maximum amplitude are 1.2 dB and 1.7 dB, respectively, and the reflection coefficient and isolation coefficient are below -19.5 dB and -9.5 dB, respectively. The phase differences between the through port #3 and the coupled port #4 are 90° ± 1° and -90° ± 11°, respectively, across the entire frequency band.

[0085] Figure 11 The simulation results are for the dual-mode Butler matrix, where (a) is the simulation result for the TEM mode, and (b) is the simulation result for the TE mode. 10 The simulation results of the mode include the S-parameters and phase difference curves of the excitation at port 1. Figure 12 The radiation beams of the dual-polarized multi-beam antenna array at 28 GHz are shown in (a) and (b) respectively. The array can achieve a wide spatial range of ±60°. The maximum gain of the x-polarization is 12.2 dBi and the maximum gain of the Y-polarization is 10.5 dBi.

[0086] In summary, this invention proposes a millimeter-wave antenna array integration method based on dual-mode substrate integrated coaxial line (Dual-Mode SICL), which utilizes TE in a single dielectric substrate. 10 The / TEM dual-mode transmission characteristic enables the first integrated design of dual-polarized radiating units and dual-mode beamforming networks. It achieves independent dual-polarized beam generation and ±60° wide-angle coverage in the 26-30GHz band within a compact size of λ0 level, solving the key technical contradiction of high integration, polarization multiplexing and low insertion loss in millimeter-wave multi-beam systems.

[0087] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A compact dual-polarized millimeter-wave multi-beam antenna array, characterized in that, It includes a dual-mode Butler matrix (2), the input end of which is provided with a transition structure (1), and the output end is provided with a dual-polarized antenna (3). The input end of the transition structure (1) is connected to a radio frequency interface. The dual-mode Butler matrix (2) includes two identical transmission structures: a first transmission structure and a second transmission structure. Both the first and second transmission structures include, sequentially arranged, a dual-mode directional coupler (201), a dual-mode phase shifter a (202), a dual-mode directional coupler a (201), and a dual-mode phase shifter b (203). A dual-mode cross-coupler (204) is provided between each of the two dual-mode phase shifters a (202) and the two dual-mode phase shifters b (203). The dual-mode Butler matrix (2) can switch between TEM mode and TE mode. 10 This mode enables independent beam control for two polarization signals. The dual-mode directional coupler (201) is formed by coupling two dual-mode substrate integrated coaxial transmission lines, and a coupling region is provided in the coupling area of ​​the two dual-mode substrate integrated coaxial transmission lines; The coupling region includes a substrate integrated waveguide coupling region (4); the substrate integrated waveguide coupling region (4) includes two second metal vias (6) and a first rectangular coupling slot (15) disposed between the second metal vias (6); a branch line coupling region (5) is provided on the first rectangular coupling slot (15); the branch line coupling region (5) includes two branch lines a (17) and branch lines b (16); the branch lines a (17) and b (16) form a "well" shaped structure; a second rectangular coupling slot (503) is provided at the center of the "well" shaped structure, and the branch line b (16) is disposed on the metal strip (7) of two dual-mode substrate integrated coaxial transmission lines; the two ends of the branch line a (17) form second rectangular protrusions (19) on the branch line b (16); a first rectangular protrusion (18) is provided between the two second rectangular protrusions (19); and three third rectangular protrusions (20) are provided on the branch line a (17) at equal intervals.

2. The compact dual-polarized millimeter-wave multibeam antenna array according to claim 1, characterized in that, The dual-mode substrate integrated coaxial transmission line includes, from bottom to top, a first metal layer (9), a first dielectric substrate (10), an adhesive sheet (11), a second dielectric substrate (12), and a second metal layer (13); the metal strip (7) is disposed between the second dielectric substrate (12) and the adhesive sheet (11); the metal strip (7) has first metal vias (8) evenly distributed on both sides; the metal vias (8) penetrate the first dielectric substrate (10), the adhesive sheet (11), and the second dielectric substrate (12).

3. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 1, characterized in that, The dual-polarized antenna (3) includes four dual-polarized antenna elements with the same structure and arranged in parallel; the dual-polarized antenna element includes a dual-mode substrate integrated coaxial transmission line; the dual-mode substrate integrated coaxial transmission line is provided with an X-polarized radiation structure (26) and a Y-polarized radiation structure (21) in sequence.

4. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 3, characterized in that, The X-polarized radiation structure (26) includes a dual-mode substrate integrated coaxial transmission line and a rectangular slot (27); the rectangular slot (27) is etched on the second metal layer (13) of the dual-mode substrate integrated coaxial transmission line; the rectangular slots (27) are spaced apart on both sides of the metal strip (7), and the horizontal distance between two rectangular slots (27) is half a wavelength.

5. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 3, characterized in that, The Y-polarized radiation structure (21) includes a transverse coupling slot (31) and a 5×5 metasurface array (22); the transverse coupling slot (31) is disposed on the second metal layer (13), and the metal strip (7) passes through the transverse coupling slot (31); the 5×5 metasurface array (22) is composed of an array of metasurface units (23); the 5×5 metasurface array (22) is provided with a first metal via (8) around its perimeter.

6. A compact dual-polarized millimeter-wave multi-beam antenna array according to claim 5, characterized in that, The metasurface unit (23) includes a rectangular metal patch (25) and an X-shaped slit (24) disposed on the rectangular metal patch (25); 7. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 1, characterized in that, The dual-mode cross-coupler (204) is composed of two dual-mode directional couplers (201) cascaded together.

8. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 1, characterized in that, The dual-mode phase shifter a (202) and dual-mode phase shifter b (203) have the same structure, both including a dual-mode substrate integrated coaxial transmission line and an extension structure (28) disposed on the dual-mode substrate integrated coaxial transmission line; the extension structure (28) includes a bent metal strip (29) and a rectangular hole (30) located inside the bent metal strip; the rectangular hole (30) is disposed on a first metal via (8) on one side of the dual-mode substrate integrated coaxial transmission line; the bend of the bent metal strip (29) is chamfered; the bent metal strip (29) and the rectangular hole (30) are respectively provided with first metal vias (8) on both sides.

9. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 7, characterized in that, The rectangular hole (30) is composed of a first metal via (8). Both the dual-mode phase shifter a (202) and the dual-mode phase shifter b (203) are coupled to the dual-mode cross coupler (204). The length of the rectangular hole (30) can be adjusted by adjusting the distance between the two coupling zones of the dual-mode cross coupler (204). The phase shift of the dual-mode phase shifter a (202) and the dual-mode phase shifter b (203) can be changed by adjusting the length of the extension structure (28). The dual-mode phase shifter a (202) is a 135° / 45° phase shifter, and the dual-mode phase shifter b (203) is a 0° phase shifter.

10. A compact dual-polarized millimeter-wave multibeam antenna array according to claim 1, characterized in that, The transition structure (1) includes eight ports, the inputs of which are connected to external RF ports, and the outputs of which are connected to the dual-mode Butler matrix (2). The eight ports include port #1, port #2, port #3, port #4, port #5, port #6, port #7, and port #8. Ports #2, #4, #6, and #8 can transmit TEM mode, while ports #1, #3, #5, and #7 can transmit TE mode. 10 model.

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