A broadband millimeter wave circularly polarized antenna element, single-mode array and dual-mode array

Abstract

This invention discloses a broadband millimeter-wave circularly polarized antenna element, a single-mode array, and a dual-mode array, relating to the field of circularly polarized antenna technology. The antenna element has a microstrip feed line on the lower surface of its second dielectric substrate; coupling gaps are etched on the metal ground layer; two metallized vias are formed on the first dielectric substrate; a metal strip is laid flat on the upper surface of the first dielectric substrate; two L-shaped parasitic patches are also laid flat on the first dielectric substrate; the two L-shaped parasitic patches are located on both sides of the metal strip, and are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate. This invention utilizes the L-shaped parasitic patches to improve the 3-dB axial ratio bandwidth of the antenna element.

Description

Technical Field

[0001] This invention relates to the field of circularly polarized antenna technology, and in particular to a broadband millimeter-wave circularly polarized antenna element, a single-mode array, and a dual-mode array. Background Technology

[0002] With the rapid development of fifth-generation (5G) mobile communication, millimeter-wave bands have been widely adopted to provide high data transmission rates and wide spectrum resources. Compared to linearly polarized antennas, which can only receive waves of the same linear polarization, circularly polarized (CP) antennas can receive waves of any linear polarization, including circularly polarized waves, thus avoiding polarization loss caused by polarization mismatch between the transmitting and receiving antennas. CP antennas have attracted significant attention due to their superior performance in resolving polarization mismatch, suppressing rain and fog interference, and eliminating the Faraday effect.

[0003] Antenna arrays are necessary to improve the transmission distance of millimeter-wave antennas. Sequentially rotated feed networks are widely used because they can further increase the axial ratio bandwidth of circularly polarized antenna arrays. Although sequentially rotated feed networks can further increase the axial ratio bandwidth of the array, the 3-dB axial ratio bandwidth enhancement is often less than 20%. This is mainly because the 3-dB axial ratio bandwidth of antenna arrays based on sequentially rotated feed networks does not always increase with the array size. That is, when the antenna elements are expanded to a 2×2 antenna subarray, the 3-dB axial ratio bandwidth can be significantly improved. However, when the 2×2 antenna subarray is expanded to a 4×4 or 8×8 antenna array, the 3-dB axial ratio bandwidth hardly increases anymore. Therefore, this results in the fact that the 3-dB axial ratio bandwidth of most millimeter-wave circularly polarized antenna arrays based on sequentially rotated feed networks remains relatively narrow. Summary of the Invention

[0004] The purpose of this invention is to provide a broadband millimeter-wave circularly polarized antenna element, a single-mode array, and a dual-mode array, which can significantly improve the axial ratio bandwidth by 3-dB.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] In a first aspect, the present invention provides a broadband millimeter-wave circularly polarized antenna element, comprising: a first dielectric substrate, a second dielectric substrate, and a metal ground layer located between the first dielectric substrate and the second dielectric substrate;

[0007] A microstrip feed line is disposed on the lower surface of the second dielectric substrate; a coupling gap is etched on the metal ground layer; two metallized vias are formed on the first dielectric substrate; a metal strip is laid flat on the upper surface of the first dielectric substrate; wherein, the two metallized vias are located at the outer edges of the coupling gaps on both sides and are in contact with the coupling gaps; one end of the metal strip is in contact with one of the metallized vias, and the other end of the metal strip is in contact with the other metallized via, so that the coupling gap is equivalent to a magnetic dipole, and the two metallized vias and the metal strip as a whole are equivalent to another magnetic dipole;

[0008] Two L-shaped parasitic patches are also laid flat on the first dielectric substrate; the two L-shaped parasitic patches are located on both sides of the metal strip, and the two L-shaped parasitic patches are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate.

[0009] Secondly, the present invention provides a single-mode array that is a 2×2 antenna subarray; the 2×2 antenna subarray includes a first sequentially rotating open ring structure, a first main feed line, and four antenna elements arranged in a sequentially rotating manner; the antenna elements are the broadband millimeter-wave circularly polarized antenna elements described in the first aspect;

[0010] The rotation direction of the four antenna elements is the same as the rotation direction of the single-mode sequential rotating feed network; the single-mode sequential rotating feed network is a feed network composed of the microstrip feed lines of the four antenna elements, the first sequential rotating open ring structure, and the first main feed line; wherein, the first sequential rotating open ring structure is connected to one end of the microstrip feed line of the four antenna elements and one end of the first main feed line, respectively.

[0011] Thirdly, the dual-mode array provided by the present invention is a 4×4 antenna array; the 4×4 antenna array includes a second sequentially rotated open ring structure, a second main feed line, and four single-mode arrays as described in the second aspect, arranged in a sequentially rotated manner.

[0012] The rotation direction of the four single-mode arrays is the same as the rotation direction of the dual-mode sequential rotating feed network; the dual-mode sequential rotating feed network is a feed network composed of four single-mode sequential rotating feed networks, a second sequential rotating open ring structure, and a second main feed line; wherein, the second sequential rotating open ring structure is connected to one end of the second main feed line and the other end of the first main feed line in the four single-mode sequential rotating feed networks respectively;

[0013] The diameter of the first sequential rotating open annular structure in the single-mode array is different from the diameter of the second sequential rotating open annular structure.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] This invention utilizes an L-shaped parasitic patch to improve the 3-dB axial ratio bandwidth of the antenna element. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the broadband millimeter-wave circularly polarized antenna unit provided by the present invention;

[0018] Figure 2 A structural parameter diagram of the first dielectric substrate and various devices on its upper surface provided by the present invention;

[0019] Figure 3 Structural parameter diagrams of the coupling slot and microstrip feeder provided by this invention;

[0020] Figure 4 The simulation results of the antenna element provided by this invention are shown in Figure S11.

[0021] Figure 5 A comparison of simulation results of axial ratio and gain of the antenna element provided by the present invention with and without L-shaped parasitic patches and with hexagonal parasitic patches;

[0022] Figure 6 The normalized radiation pattern of the antenna element provided by the present invention at a frequency of 30 GHz;

[0023] Figure 7 The normalized radiation pattern of the antenna element provided by this invention at the 35GHz frequency point;

[0024] Figure 8 This is a schematic diagram of the structure of the 2×2 antenna subarray provided by the present invention;

[0025] Figure 9 This is a diagram of the single-mode sequential rotating power supply network structure provided by the present invention;

[0026] Figure 10 Simulation results of S11, axial ratio, and gain for the 2×2 antenna subarray provided by this invention;

[0027] Figure 11 The normalized radiation pattern of the 2×2 antenna subarray at 24GHz provided by this invention;

[0028] Figure 12 The normalized radiation pattern of the 2×2 antenna subarray at 35GHz frequency provided by the present invention;

[0029] Figure 13 This is a structural diagram of the dual-mode sequential rotating power supply network provided by the present invention;

[0030] Figure 14 This is a schematic diagram of the structure of the 4×4 antenna array provided by the present invention;

[0031] Figure 15 The structural parameter diagram of the radiating structure of the 4×4 antenna array provided by the present invention;

[0032] Figure 16 A planar structural diagram of the sixth dielectric substrate of the 4×4 antenna array provided by the present invention;

[0033] Figure 17 A planar structural diagram of the eighth dielectric substrate of the 4×4 antenna array provided by the present invention;

[0034] Figure 18 The diagram shows the EBG parameters and simulated reflection phase results in the 4×4 antenna array provided by this invention.

[0035] Figure 19 The normalized radiation pattern of the xoz plane at a frequency of 29 GHz with and without EBG for the 4×4 antenna array provided by this invention.

[0036] Figure 20 The normalized radiation pattern of the yoz plane at a frequency of 29 GHz with and without EBG for the 4×4 antenna array provided by this invention.

[0037] Figure 21 The simulation S11 result diagram of the 4×4 antenna array provided by the present invention;

[0038] Figure 22 The simulation axial ratio and gain results of the 4×4 antenna array provided by this invention are shown in the figure.

[0039] Figure 23 The normalized radiation pattern of the 4×4 antenna array at 23GHz frequency provided by the present invention;

[0040] Figure 24 The normalized radiation pattern of the 4×4 antenna array at 28GHz frequency provided by the present invention;

[0041] Figure 25 The normalized radiation pattern of the 4×4 antenna array provided by this invention at the 33GHz frequency point. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] This embodiment provides a broadband millimeter-wave circularly polarized antenna element (hereinafter referred to as the antenna element), such as Figure 1 As shown, the location of each structure in the antenna element and the relationship between them can be observed.

[0046] The antenna unit includes a first dielectric substrate 1, a second dielectric substrate 2, and a metal ground layer 3 located between the first dielectric substrate 1 and the second dielectric substrate 2. A microstrip feed line 5 is disposed on the lower surface of the second dielectric substrate 2, wherein one end of the microstrip feed line 5 is a microstrip feed port 4, and the other end of the microstrip feed line 5 extends to the lower surface of the second dielectric substrate 2. Coupling gaps 6 are etched on the metal ground layer 3. Two metallized vias 8 are formed on the first dielectric substrate 1, and a metal strip 7 is laid flat on the upper surface of the first dielectric substrate 1. The two metallized vias 8 are located at the outer edges of the coupling gaps 6 and are in contact with the coupling gaps 6. One end of the metal strip 7 is in contact with one metallized via, and the other end of the metal strip 7 is in contact with the other metallized via, so that the coupling gap is equivalent to a magnetic dipole, and the two metallized vias and the metal strip 7 as a whole are equivalent to another magnetic dipole.

[0047] Two L-shaped parasitic patches 9 are also laid flat on the first dielectric substrate 1; the two L-shaped parasitic patches 9 are located on both sides of the metal strip 7, and the two L-shaped parasitic patches 9 are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate 1. The coupling of the two L-shaped parasitic patches 9 with the metal strip 7 generates another new CP resonant point, which improves the 3-dB axial ratio bandwidth.

[0048] Preferably, in this embodiment, four hexagonal parasitic patches 10 are also laid flat on the first dielectric substrate 1; the four hexagonal parasitic patches 10 are located on both sides of the metal strip 7, and the four hexagonal parasitic patches 10 are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate 1. This arrangement can further improve the 3-dB axial ratio bandwidth and radiation gain.

[0049] Furthermore, a first hexagonal parasitic patch, a first L-shaped parasitic patch, and a second hexagonal parasitic patch are sequentially laid on one outer side of the metal strip 7; a third hexagonal parasitic patch, a second L-shaped parasitic patch, and a fourth hexagonal parasitic patch are sequentially laid on the other outer side of the metal strip 7. The metal substrate 3, the metal strip 7, the L-shaped parasitic patch, and the hexagonal parasitic patch 10 are all made of copper.

[0050] Preferably, the metal strip 7 described in this embodiment is the main radiating structure of the antenna element; the coupling gap 6 is processed by etching in the middle region of the metal ground layer 3, so that the coupling gap 6 is located in the middle of the metal ground layer 3, which is equivalent to a gap cut in the middle of the metal ground layer 3. Its functions are: first, to excite the radiating structure of the antenna element to generate radiation through the coupling gap 6; and second, to act as a magnetic dipole M1.

[0051] Furthermore, in this embodiment, the metallized via 8 is located within the first dielectric substrate 1, with a height of 1.575 mm and a radius of 0.2 mm. The metallized via 8 is in contact with the surfaces of the metal strip 7 and the metal ground layer 3. Simultaneously, the two metallized vias are respectively in contact with the two sides of the narrow side of the coupling gap 6. That is, one metallized via is located at the outer edge of one long side of the coupling gap and in contact with one long side of the coupling gap, and one metallized via is close to one wide side of the coupling gap; the other metallized via is located at the outer edge of the other long side of the coupling gap and in contact with the other long side of the coupling gap, and the other metallized via is close to the other wide side of the coupling gap. The two metallized vias 8 adjacent to the coupling gap 6 and the metal strip 7 located on the upper surface of the first dielectric substrate 1 can be equivalent to a classic loop, which is equivalent to another magnetic dipole M2, forming a pair of magnetic dipoles with the coupling gap 6.

[0052] like Figure 2 As shown, the first dielectric substrate is a Rogers 5880 dielectric substrate with a thickness of 1.575 mm, a width W of 10 mm, a length L of 10 mm, and a dielectric constant of 2.2; the loss angle of the first dielectric substrate is tanδ=0.0009.

[0053] The length of the metal strip in the x-axis direction is L1 = 5.2 mm, and the width of the metal strip is wf = 0.4 mm; the distance between the metal strip and the L-shaped parasitic patch in the y-axis direction is g3 = 0.05 mm; the structural parameters of the L-shaped parasitic patch are l2 = 0.8 mm, l3 = 0.7 mm, w2 = 1.2 mm, and w3 = 0.2 mm; the structural parameters of the hexagonal parasitic patch are w1 = 0.6 mm, wp = 0.5 mm, and p = 1.5 mm; on one side of the same metal strip, the distance between the L-shaped parasitic patch and a hexagonal parasitic patch is g1 = 0.05 mm, and the distance between the L-shaped parasitic patch and another hexagonal parasitic patch is g2 = 0.05 mm.

[0054] like Figure 3 As shown, the length of the microstrip feed line is w4 = 6.1 mm, the width is ls = 0.55 mm, the distance between the microstrip feed line and the second dielectric substrate is l5 = 4.725 mm; the width of the coupling gap is w5 = 0.6 mm, the length is l4 = 7.0 mm; and the diameter of the metallized via is R = 0.4 mm.

[0055] The second dielectric substrate 2 uses Rogers 5880 dielectric substrate with a thickness of 0.254 mm, a width of 10 mm, a length of 10 mm, and a dielectric constant of 2.2; the loss angle of the second dielectric substrate 2 is tanδ=0.0009.

[0056] Figure 4 The simulation results of the antenna element for S11 are shown in the figure; for example... Figure 4 As shown, the simulation results show that the -10dBS11 bandwidth of the antenna element is 25.4GHz-40.2GHz (relative bandwidth of 45.1%).

[0057] Figure 5 The image shows a comparison of simulation results for the axial ratio and gain of the antenna element with and without L-shaped parasitic patches and with hexagonal parasitic patches; for example... Figure 5 As shown, the results indicate that the antenna element exhibits the widest axial ratio bandwidth and highest gain when both L-shaped and hexagonal parasitic patches are present. Specifically, with both L-shaped and hexagonal parasitic patches, the antenna element's 3-dB axial ratio bandwidth can cover the 29.3GHz-37.0GHz frequency band (relative bandwidth of 23.2%). Axial ratio is an indicator of whether an antenna can radiate circularly polarized waves; generally, an antenna with an axial ratio below 3-dB at a certain frequency is considered to radiate circularly polarized waves. Its 1-dB right-hand circular CP gain bandwidth is approximately 29.1GHz-34.9GHz (relative bandwidth of 18.1%), and the peak right-hand circular CP gain is approximately 8.6dBic.

[0058] Figure 6 The normalized radiation pattern of the antenna element at 30 GHz is given by... Figure 6It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0059] Figure 7 The normalized radiation pattern of the antenna element at 35 GHz is given by... Figure 7 It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0060] The antenna unit provided in this embodiment has the following advantages:

[0061] 1) Circularly polarized radiation

[0062] To generate CP radiation, two orthogonal electric field components with the same amplitude and a 90° phase difference are required. For example... Figure 1 As shown, the metal strip 7 is located on the upper surface of the first dielectric substrate 1 and serves as the radiating structure of the antenna, excited by the coupling slot 6 etched on the metal ground layer 3. The coupling slot 6 can be equivalent to a magnetic dipole (M1), which generates a horizontal electric field component. The combination of the two metallized vias 8 and the metal strip 7 can be equivalent to a classical loop, which is equivalent to another magnetic dipole (M2), generating a vertical electric field component. M1 and M2 are orthogonal to each other, forming a pair of orthogonal magnetic dipoles (OMDs), which can generate orthogonal electric fields. Since the thickness of the first dielectric substrate is 1.575 mm, which is approximately 1 / 4 λg of the center frequency (λg is the wavelength in the dielectric), a 90° phase difference is provided, thus enabling CP radiation.

[0063] 2) Increased shaft ratio bandwidth

[0064] First, rotationally symmetrical L-shaped parasitic patches 9 are added to both sides of the metal strip 7; due to the coupling effect between the L-shaped parasitic patches 9 and the metal strip 7, a new CP resonant point can be generated. For example... Figure 5 As shown, the 3-dB axial ratio bandwidth of the antenna element can be widened. To further obtain a wider 3-dB axial ratio bandwidth while achieving higher gain, four hexagonal parasitic patches 10 are placed around the metal strip 7, altering the surface current distribution. Due to the parasitic effect, the 3-dB axial ratio bandwidth of the antenna element is widened. Figure 5As shown, without either the L-shaped or hexagonal parasitic patch, the 3-dB axial ratio bandwidth is 11.2% (29.5-33.0 GHz), and the peak right-hand CP gain is 6.4 dBic. After the axial ratio bandwidth is improved, i.e., with both L-shaped and hexagonal parasitic patches, the 3-dB axial ratio bandwidth of the antenna element can reach 23.2% (29.3-37.0 GHz), and the peak right-hand CP gain is approximately 8.6 dBic. Compared to the original state of the antenna element (without either the L-shaped or hexagonal parasitic patch), the 3-dB axial ratio bandwidth of the antenna element provided in this embodiment is improved by 12.0%, and the peak right-hand CP gain is improved by approximately 2.2 dBic.

[0065] Example 2

[0066] like Figure 8 As shown, the single-mode array provided in this embodiment is a 2×2 antenna subarray. The 2×2 antenna subarray mainly includes four antenna elements 13. The location of each structure in the 2×2 antenna subarray and the relationship between them can be observed.

[0067] The 2×2 antenna subarray includes a first sequentially rotating open ring structure, a first main feed line, and four antenna elements 13 arranged in a sequentially rotating manner. The antenna elements 13 are the broadband millimeter-wave circularly polarized antenna elements described in Embodiment 1. The rotation direction of the four antenna elements 13 is the same as the rotation direction of the single-mode sequentially rotating feed network 14. The single-mode sequentially rotating feed network 14 is a feed network composed of the microstrip feed lines of the four antenna elements 13, the first sequentially rotating open ring structure, and the first main feed line. The first sequentially rotating open ring structure is connected to one end of the microstrip feed line of the four antenna elements 13 and one end of the first main feed line, respectively.

[0068] In this embodiment, the four antenna elements 13 share the same dielectric substrate. Specifically, the first dielectric substrate of the four antenna elements 13 is the third dielectric substrate 11, and the second dielectric substrate of the four antenna elements 13 is the fourth dielectric substrate 12. The other end of the microstrip feed line extends to the lower surface of the second dielectric substrate of the antenna element. The other end of the first main feed line is the microstrip feed port.

[0069] In this embodiment, the third dielectric substrate 11 and the fourth dielectric substrate 12 are adjacent to each other. The third dielectric substrate 11 is a Rogers 5880 dielectric substrate with a thickness of 1.575 mm, a width Wb of 15 mm, a length Lb of 15 mm, and a dielectric constant of 2.2. The loss angle of the third dielectric substrate 11 is tanδ = 0.0009. The fourth dielectric substrate 12 is a Rogers 5880 dielectric substrate with a thickness of 0.254 mm, a width of 15 mm, a length of 15 mm, and a dielectric constant of 2.2. The loss angle of the fourth dielectric substrate 12 is tanδ = 0.0009. In two adjacent antenna elements 13, the distance D1 between the center point of the metal strip in one antenna element and the center point of the metal strip in the other antenna element is 7.5 mm.

[0070] A single-mode sequential rotating feed network rotates clockwise, generating phases of 0°, 90°, 180°, and 270° at the four output ports, respectively. The phase difference between adjacent output ports is 90°, and the electric fields are orthogonal, thus producing circularly polarized radiation and enhancing the circular polarization bandwidth of the subarray. For example... Figure 9 As shown, the diameter R1 of the first sequential rotating open annular structure is 1.6 mm; the first sequential rotating open annular structure is divided into a first arc segment, a second arc segment, a third arc segment, and a fourth arc segment in a clockwise direction; the distance between the inner and outer rings of the first arc segment is f1 = 0.63 mm, the distance between the inner and outer rings of the second arc segment is f2 = 0.52 mm, the distance between the inner and outer rings of the third arc segment is f3 = 0.4 mm, and the distance between the inner and outer rings of the fourth arc segment is f4 = 0.2 mm. The microstrip feed line includes a straight microstrip feed line and a broken-line microstrip feed line. The width of the straight microstrip feed line is Wk = 0.46 mm; the broken-line microstrip feed line includes a first broken-line microstrip feed line and a second microstrip feed line connected to the first microstrip feed line. The width of the first microstrip feed line is f5 = 0.46 mm, and the width of the second microstrip feed line is f6 = 0.55 mm.

[0071] Figure 10 The simulation results for S11, axial ratio, and gain of a 2×2 antenna subarray are shown in the figure; Figure 10 It can be seen that the -10dB S11 bandwidth of the 2×2 antenna subarray is 60.3%.

[0072] (20.6GHz-38.4GHz), with a 3dB-axis ratio bandwidth of 48.3% (22.8GHz-37.3GHz) and a peak right-hand gain of 12.0dBic. Compared to the antenna element, the 3dB-axis ratio bandwidth has increased by 25.1%.

[0073] Figure 11 The normalized radiation pattern of the 2×2 antenna subarray at 24 GHz; Figure 11It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0074] Figure 12 The normalized radiation pattern of the 2×2 antenna subarray at 35 GHz is given by... Figure 12 It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0075] The 2×2 antenna subarray provided in this embodiment of the invention has the following advantages:

[0076] Based on the antenna element described in Embodiment 1, a 2×2 antenna subarray was designed using a traditional 1-to-4 single-mode sequential rotating feed network, as shown in the structure below. Figure 8 and Figure 9 As shown, the 2×2 antenna subarray is designed on a double-layer Rogers 5880 dielectric substrate, with a single-mode sequential rotating feed network located on the lower surface of the fourth dielectric substrate. Energy is coupled to each antenna element through four coupling slots. By optimizing the distance between adjacent antenna elements and the structural parameters of the sequential rotating feed network using HFSS electromagnetic simulation software, approximately equal power and a 90° phase difference can be obtained, thereby further improving the axial ratio (AR) bandwidth of the 2×2 antenna subarray.

[0077] Example 3

[0078] This embodiment provides a dual-mode array. The dual-mode array is a 4×4 antenna array. The 4×4 antenna array includes a second sequentially rotating open ring structure, a second main feed line, and four single-mode arrays arranged in a sequentially rotating manner as described in Embodiment 2; the rotation direction of the four single-mode arrays is the same as the rotation of the dual-mode sequentially rotating feed network.

[0079] The third dielectric substrate of the four single-mode arrays is the same dielectric substrate, and the fourth dielectric substrate of the four single-mode arrays is the same dielectric substrate.

[0080] In traditional antenna array designs based on sequential rotating feed networks, the axial bandwidth ratio is significantly enhanced when the antenna elements are expanded into a 2×2 antenna subarray. However, when the 2×2 antenna subarray is expanded into a 4×4 antenna array, the axial bandwidth ratio of the 4×4 antenna array hardly increases further. This is mainly because current designs for circularly polarized antenna arrays based on sequential rotating feed networks focus primarily on the structure and shape of the sequential rotating open ring of the feed network. Furthermore, the structure and diameter of the first sequential rotating open ring in the 2×2 antenna subarray are identical to those of the second sequential rotating open ring in the 4×4 antenna array. This only generates one CP resonant point, resulting in a limited increase in axial bandwidth ratio. Currently, to the best of our knowledge, no researchers have designed sequential rotating open ring structures with different structures and diameters and applied them to 4×4 or larger-scale antenna arrays. In this embodiment, firstly, when the antenna elements form a 2×2 antenna subarray, the diameter of the first sequential rotating open ring structure used to connect the four antenna elements is R1. At this time, the 2×2 antenna subarray can generate one CP resonant point. Since this sequential rotating feed network only has one first sequential rotating open ring structure with a diameter of R1, it is called a single-mode sequential rotating feed network. Then, when the 2×2 antenna subarray is further expanded into a 4×4 antenna array, the diameter of the second sequential rotating open ring structure used to connect the four 2×2 antenna subarrays is R2. At this time, the 2×2 antenna subarray can be equivalent to one antenna element. Since the diameters R1 and R2 are different, the generated CP resonant points are different. Therefore, theoretically, the 4×4 antenna array can obtain another new CP resonant point. By optimizing the size of the diameter R2 and the structural parameters of the second sequential rotating open ring structure, the two CP resonant points (generated by sequential rotating open ring structures with diameters of R1 and R2 respectively) can be combined together, further expanding the axial ratio bandwidth of the antenna array. Since the proposed sequential rotating feed network for the 4×4 antenna array has two sequential rotating open ring structures (with diameters R1 and R2 respectively), it is called a dual-mode sequential rotating feed network.

[0081] like Figure 13As shown, the dual-mode sequential rotating feed network is a feed network composed of four single-mode sequential rotating feed networks, a second sequential rotating open-ring structure, and a second main feeder. The second sequential rotating open-ring structure is connected to one end of the second main feeder and the other end of the first main feeder in the four single-mode sequential rotating feed networks. The other end of the second main feeder is a microstrip feed port. The diameter of the first sequential rotating open-ring structure in the single-mode array is different from the diameter of the second sequential rotating open-ring structure. The sizes of the first, second, third, and fourth arc segments of the first sequential rotating open-ring structure in the single-mode array are different from the sizes of the first, second, third, and fourth arc segments of the second sequential rotating open-ring structure.

[0082] The first main feeder is divided into three segments in sequence. The width of the first segment is K1 = 0.2 mm, the width of the second segment is K2 = 0.5 mm, and the width of the third segment is K3 = 0.55 mm. Its length is K4 = 5.09 mm. The length of the second main feeder is K = 26.91 mm, and its width is Kf = 0.6 mm. Its diameter is R1 = 1.6 mm and its diameter is R2 = 2.34 mm. The second sequential rotating open ring structure is divided into four arc segments in sequence. The distances between the inner and outer rings of each arc segment are S1 = 0.75 mm, S2 = 0.66 mm, S3 = 0.46 mm, and S4 = 0.15 mm, respectively. The width of the connection end with the second sequential rotating open ring structure is S5 = 0.24 mm.

[0083] Figure 14 This is a schematic diagram of a 4×4 antenna array; Figure 14 It can be observed that the locations of each structure in the 4×4 antenna array and their relationships are as follows:

[0084] The 4×4 antenna array includes, from top to bottom, a fifth dielectric substrate 15, a sixth dielectric substrate 16, a seventh dielectric substrate 17, an eighth dielectric substrate 18, and a ninth dielectric substrate 19; the third dielectric substrate of the four single-mode arrays is the same dielectric substrate, which is the fifth dielectric substrate 15; the fourth dielectric substrate of the four single-mode arrays is the same dielectric substrate, which is the ninth dielectric substrate 19.

[0085] The fifth dielectric substrate 15 uses Rogers 5880 dielectric substrate, with a thickness of 1.575 mm, a width of 32.5 mm, a length of 32.5 mm, a dielectric constant of 2.2, and a loss angle of tanδ = 0.0009.

[0086] The sixth dielectric substrate 16 uses a Rogers 5880 dielectric substrate with a thickness of 0.127 mm, a width of 32.5 mm, a length of 32.5 mm, a dielectric constant of 2.2, and a loss angle tanδ = 0.0009. To reduce dielectric loss, the sixth dielectric substrate 16 has a hollowed-out design in the middle, i.e., a hollowed-out design is made in the middle of the planar dielectric substrate. The front end of the sixth dielectric substrate 16 has a protruding "T"-shaped structure designed for mounting RF adapters, which has almost no impact on overall performance or innovation.

[0087] The seventh dielectric substrate 17 uses a Rogers 5880 dielectric substrate with a thickness of 0.127 mm, a width of 32.5 mm, a length of 32.5 mm, a dielectric constant of 2.2, and a loss angle tanδ = 0.0009. The front end of the seventh dielectric substrate 17 has a protruding "T"-shaped structure designed for mounting RF adapters, which has almost no impact on overall performance or innovation.

[0088] The eighth dielectric substrate 18 uses a Rogers 5880 dielectric substrate with a thickness of 0.381 mm, a width of 32.5 mm, a length of 32.5 mm, a dielectric constant of 2.2, and a loss angle tanδ = 0.0009. To reduce dielectric loss, the eighth dielectric substrate 18 has a hollowed-out design in the middle, i.e., a hollowed-out design is made in the middle of the planar dielectric substrate.

[0089] The ninth dielectric substrate 9 uses Rogers 5880 dielectric substrate, with a thickness of 1.575 mm, a width of 32.5 mm, a length of 32.5 mm, a dielectric constant of 2.2, and a loss angle of tanδ = 0.0009.

[0090] The fifth dielectric substrate 15, the sixth dielectric substrate 16, the seventh dielectric substrate 17, the eighth dielectric substrate 18, and the ninth dielectric substrate 19 are adjacent to each other.

[0091] Antenna element 20 is the antenna element structure described in Embodiment 1, totaling 16 (4×4), all located in the fifth dielectric substrate 15. The first metal ground layer 21 is located on the lower surface of the fifth dielectric substrate 15, made of copper, and has 16 (4×4) coupling slots cut out. The second metal ground layer 22 is located on the front upper surface of the sixth dielectric substrate 16, sharing a common ground with the first metal ground layer 21 (the first metal ground layer 21 and the second metal ground layer 22 are in close contact), realizing the grounding of the RF adapter. The cut-out air layer 23 is the hollow structure between the sixth dielectric substrate 16 and the sixth dielectric substrate 18. The dual-mode sequential rotating feed network 24 is as follows... Figure 13As shown, an electromagnetic bandgap structure (EBG) 25 is disposed on the ninth dielectric substrate 19. This EBG structure is used to reduce the back radiation of the 4×4 antenna array.

[0092] Figure 15 Here is a diagram showing the structural parameters of the radiating structure of a 4×4 antenna array; for example... Figure 15 As shown, the sixth dielectric substrate has a width Wm = 32.5 mm and a length Lm = 32.5 mm; in two adjacent antenna elements, the distance D2 between the center point of the metal strip in one antenna element and the center point of the metal strip in the other antenna element is 7.7 mm; the protruding portion has a width Wb = 6.0 mm and a length Lb = 5.0 mm. The radiating structure of this 4×4 antenna array is located on the upper surface of the fifth dielectric substrate.

[0093] Figure 16 This is a planar structural diagram of the sixth dielectric substrate for a 4×4 antenna array, as shown below. Figure 16 As shown, the area cut out in the middle of the sixth dielectric substrate is an air layer with a side length of Wp = 23.0 mm.

[0094] Figure 17 The planar structure diagram of the eighth dielectric substrate for the 4×4 antenna array is shown below. Figure 17 As shown, the area cut out in the middle of the eighth dielectric substrate is an air layer with a side length of Wg = 28.0 mm.

[0095] Figure 18 The diagram shows the EBG parameters and simulated reflection phase results for a 4×4 antenna array, as follows. Figure 18 As shown, the outer edge Wt = 1.0 mm and the inner edge Le = 0.6 mm of EBG. The simulated -90° to 90° reflection phase bandwidth is approximately 18.4 GHz to 40.0 GHz, and in-phase reflection can be achieved within this bandwidth range.

[0096] Figure 19 The normalized radiation pattern of the xoz plane at 29 GHz is a simulation of a 4×4 antenna array with and without EBG. Figure 19 It can be seen that, compared with the antenna radiation pattern without EBG, the antenna radiation pattern with EBG has a significantly smaller back lobe and a higher front-to-back ratio.

[0097] Figure 20 The normalized radiation pattern of the yoz plane at 29 GHz is a simulation of a 4×4 antenna array with and without EBG. Figure 20 It can be seen that, compared with the antenna radiation pattern without EBG, the antenna radiation pattern with EBG has a significantly smaller back lobe and a higher front-to-back ratio.

[0098] Figure 21 The simulation results of S11 for a 4×4 antenna array are shown in the figure. Figure 21 It can be observed that the -10dB S11 bandwidth of the 4×4 antenna array is 81.2% (18.8GHz–44.5GHz).

[0099] Figure 22 The simulation results of the axial ratio and gain of the 4×4 antenna array are shown in the figure. Figure 22 It can be observed that the 3dB-axis ratio bandwidth of the 4×4 antenna array is 62.9% (19.6–37.6 GHz), with a peak right-hand gain of 16.9 dBic. Compared to the 2×2 antenna subarray, the 3dB-axis ratio bandwidth further increases by 14.6% (the axial ratio bandwidth of traditional single-mode sequential rotating feed antenna arrays hardly increases when the 2×2 antenna subarray is extended to a 4×4 antenna array). Compared to antenna elements, the 3dB-axis ratio bandwidth of the 4×4 antenna array increases by 39.7%.

[0100] Figure 23 The normalized radiation pattern of a 4×4 antenna array at 23 GHz is given by... Figure 23 It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0101] Figure 24 The normalized radiation pattern of a 4×4 antenna array at 28 GHz is given by... Figure 24 It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0102] Figure 25 The normalized radiation pattern of a 4×4 antenna array at 33 GHz is given by... Figure 25 It can be seen that the antenna radiates right-hand circularly polarized waves in the +z direction and exhibits obvious unidirectional radiation characteristics. The left-hand circularly polarized waves are much smaller than the right-hand circularly polarized waves.

[0103] This invention provides a broadband millimeter-wave circularly polarized antenna element (i.e., a broadband orthogonal magnetic dipole circularly polarized antenna element), a single-mode array (i.e., a 2×2 orthogonal magnetic dipole circularly polarized antenna subarray), and a dual-mode array (i.e., a 4×4 orthogonal magnetic dipole circularly polarized antenna array). The broadband orthogonal magnetic dipole antenna element includes a pair of orthogonal equivalent magnetic dipoles (forming circularly polarized radiation), an L-shaped parasitic patch and a hexagonal parasitic patch (enhancing the 3-dB axial ratio bandwidth (i.e., the circularly polarized bandwidth)), a first dielectric substrate, and a second dielectric substrate. The 2×2 orthogonal magnetic dipole circularly polarized antenna subarray includes: a single-mode sequential rotating feed network, 4 antenna elements, a third dielectric substrate, and a fourth dielectric substrate. The 4×4 orthogonal magnetic dipole circularly polarized antenna subarray includes: a dual-mode sequential rotating feed network, 16 antenna elements, an electromagnetic bandgap (EBG) structure, a fifth dielectric substrate, a sixth dielectric substrate, a seventh dielectric substrate, an eighth dielectric substrate, and a ninth dielectric substrate. This invention utilizes L-shaped and hexagonal parasitic patches to enhance the 3-dB axial ratio bandwidth of the orthogonal magnetic dipole antenna element. Furthermore, it employs a dual-mode sequential rotating feed network to significantly improve the 3-dB axial ratio bandwidth of the 4×4 antenna array (the bandwidth improvement is almost twice that of the traditional sequential rotating feed network). In addition, this planar array also has advantages such as simple structure, ease of processing, manufacturing and integration. The specific advantages are as follows.

[0104] 1) The AR bandwidth of the antenna element was further enhanced by using L-shaped parasitic patches and hexagonal parasitic patches.

[0105] 2) A novel dual-mode sequential rotating feed network is proposed for the first time, and a 4×4 antenna array is designed based on this network. This solves the problem that the 3-dB axial ratio bandwidth of current antenna array designs based on sequential rotating feed networks hardly increases further when transitioning from a 2×2 antenna subarray to a 4×4 antenna array. Simulation results show that the dual-mode sequential rotating feed network can significantly improve the 3-dB axial ratio bandwidth of both the 2×2 and 4×4 antenna subarrays, achieving a wider 3-dB axial ratio bandwidth. When the element is expanded to a 2×2 antenna subarray, the 3-dB axial ratio bandwidth can increase by 25.1%. When the 2×2 antenna subarray is expanded to a 4×4 antenna array, the 3-dB axial ratio bandwidth can increase again by 14.6%. Final simulation results show that the impedance and 3-dB axial ratio bandwidth of the 4×4 antenna array reach 81.2% (18.8–44.5 GHz) and 62.9% (19.6–37.6 GHz), respectively. Compared to antenna elements, the 3dB-axis ratio bandwidth of the 4×4 antenna array is increased by 39.7% (almost twice the 3-dB-axis ratio bandwidth of a conventional single-mode sequential rotating feed network).

[0106] 3) An EBG structure was introduced into the 4×4 antenna array, which reduced the array's back radiation and improved the front-to-back ratio (FBR) and gain. To reduce dielectric loss, the middle portion of the sixth and eighth dielectric substrates was hollowed out.

[0107] 4) Currently, the design and implementation of ultra-wideband circularly polarized millimeter-wave antenna arrays face certain challenges. Using the proposed dual-mode sequential rotating feed network to design a circularly polarized millimeter-wave antenna array can more easily achieve ultra-wideband radiation and, like other traditional sequential rotating feed networks, is compatible with various types of antenna elements. This provides a simple method for realizing ultra-wideband circularly polarized antenna arrays. Furthermore, the dual-mode sequential rotating feed network can be extended to a multi-mode sequential rotating feed network, potentially achieving a higher 3-dB axial ratio bandwidth enhancement. Further design improvements are also possible, such as employing substrate-integrated waveguide structures and reducing the use of dielectric substrates, to further improve gain.

[0108] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0109] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A broadband millimeter-wave circularly polarized antenna element, characterized in that, include: A first dielectric substrate, a second dielectric substrate, and a metal ground layer located between the first dielectric substrate and the second dielectric substrate; A microstrip feed line is disposed on the lower surface of the second dielectric substrate; coupling gaps are etched on the metal ground layer; two metallized vias are formed on the first dielectric substrate; a metal strip is laid flat on the upper surface of the first dielectric substrate; wherein, two of the metallized vias are located at the outer edges of the coupling gaps on both sides and in contact with the coupling gaps; one of the metallized vias is located at the outer edge of one long side of the coupling gap and in contact with one long side of the coupling gap, and one of the metallized vias is close to one wide side of the coupling gap; the other of the metallized vias is located at the outer edge of the other long side of the coupling gap and in contact with the other long side of the coupling gap, and the other of the metallized vias is close to the other wide side of the coupling gap; one end of the metal strip is in contact with one of the metallized vias, and the other end of the metal strip is in contact with the other metallized via, so that the coupling gap is equivalent to a magnetic dipole, and the two metallized vias and the metal strip as a whole are equivalent to another magnetic dipole; Two L-shaped parasitic patches are also laid flat on the first dielectric substrate; the two L-shaped parasitic patches are located on both sides of the metal strip, and the two L-shaped parasitic patches are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate.

2. The broadband millimeter-wave circularly polarized antenna element according to claim 1, characterized in that, Four hexagonal parasitic patches are also laid flat on the first dielectric substrate; the four hexagonal parasitic patches are located on both sides of the metal strip, and the four hexagonal parasitic patches are rotationally symmetrical about the center point of the upper surface of the first dielectric substrate.

3. A broadband millimeter-wave circularly polarized antenna element according to claim 2, characterized in that, On one outer side of the metal strip, a first hexagonal parasitic patch, a first L-shaped parasitic patch, and a second hexagonal parasitic patch are laid in sequence; on the other outer side of the metal strip, a third hexagonal parasitic patch, a second L-shaped parasitic patch, and a fourth hexagonal parasitic patch are laid in sequence.

4. A single-mode array, characterized in that, The single-mode array is a 2×2 antenna subarray; the 2×2 antenna subarray includes a first sequentially rotating open ring structure, a first main feed line, and four antenna elements arranged in a sequentially rotating manner; the antenna element is the broadband millimeter-wave circularly polarized antenna element as described in claim 2; The rotation direction of the four antenna elements is the same as the rotation direction of the single-mode sequential rotating feed network; the single-mode sequential rotating feed network is a feed network composed of the microstrip feed lines of the four antenna elements, the first sequential rotating open ring structure, and the first main feed line; wherein, the first sequential rotating open ring structure is connected to one end of the microstrip feed line of the four antenna elements and one end of the first main feed line, respectively.

5. A single-mode array according to claim 4, characterized in that, The first dielectric substrate of the four antenna elements is the same dielectric substrate, and the second dielectric substrate of the four antenna elements is the same dielectric substrate; The other end of the microstrip feed line extends to the lower surface of the second dielectric substrate of the antenna unit; the other end of the first main feed line is a microstrip feed port.

6. A dual-mode array, characterized in that, The dual-mode array is a 4×4 antenna array; the 4×4 antenna array includes a second sequentially rotating open ring structure, a second main feed line, and four single-mode arrays as described in claim 5 arranged in a sequentially rotating manner; The rotation direction of the four single-mode arrays is the same as the rotation direction of the dual-mode sequential rotating feed network; the dual-mode sequential rotating feed network is a feed network composed of four single-mode sequential rotating feed networks, a second sequential rotating open ring structure, and a second main feed line; wherein, the second sequential rotating open ring structure is connected to one end of the second main feed line and the other end of the first main feed line in the four single-mode sequential rotating feed networks respectively; The diameter of the first sequential rotating open annular structure in the single-mode array is different from the diameter of the second sequential rotating open annular structure.

7. A dual-mode array according to claim 6, characterized in that, The dual-mode array comprises, from top to bottom, a fifth dielectric substrate, a sixth dielectric substrate, a seventh dielectric substrate, an eighth dielectric substrate, and a ninth dielectric substrate; The third dielectric substrate of the four single-mode arrays is the same dielectric substrate, and is the fifth dielectric substrate; The fourth dielectric substrate of the four single-mode arrays is the same dielectric substrate, and is the ninth dielectric substrate.

8. A dual-mode array according to claim 7, characterized in that, The front ends of both the sixth dielectric substrate and the seventh dielectric substrate are protruding T-shaped structures; the T-shaped structures are used to mount radio frequency adapters.

9. A dual-mode array according to claim 7, characterized in that, The sixth dielectric substrate and the eighth dielectric substrate are both dielectric substrates that have been hollowed out in the middle of a planar dielectric substrate; the ninth dielectric substrate is also provided with an electromagnetic bandgap structure.

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