Low-profile dual-circularly-polarized Ka-band phased-array antenna

Abstract

The invention discloses a low-profile dual-circularly-polarized Ka-band phased-array antenna which mainly solves the problems that a traditional circularly-polarized phased-array antenna is high in profile, complex in structure and incapable of polarization multiplexing. The antenna feed structure and the metal patch structure are symmetrical, the left-hand and right-hand circular polarization feed ports are directly connected with the radiation patch to excite the patch to generate left-hand circular polarization and right-hand circular polarization respectively, regulation and control from single circular polarization to dual circular polarization are achieved, the left-hand and right-hand circular polarization feed ports are directly connected with the radiation patch, and the radiation patch is directly connected with the left-hand and right-hand circular polarization feed ports. The patches are excited to generate left-hand circular polarization and right-hand circular polarization respectively, other extra structures are not introduced, the antenna design process is simplified, and polarization multiplexing of the circularly polarized antenna is achieved. The antenna is composed of the two layers of dielectric plates, a complex middle feed network is omitted, and the antenna has the advantages of being simple in structure and low in profile.

Description

Technical Field

[0001] The present invention belongs to the field of radar communication technology, and further relates to a low-profile dual circularly polarized Ka-band phased array antenna in the field of antenna technology. The present invention can be used for millimeter wave antenna communication and high-resolution radar imaging. Background Art

[0002] In radio communication systems such as satellite positioning, radar detection, and electronic countermeasures, in order to quickly and accurately obtain weak signals transmitted by satellites, the antenna of the system is generally required to have a wider beam width and be able to achieve wide-angle circular polarization coverage. Therefore, circularly polarized phased array antennas that meet engineering requirements are increasingly widely used. The polarization mode of circularly polarized phased array antennas can suppress multipath attenuation, reduce system complexity, and solve the shortcomings of linear polarization such as channel fading and insufficient channel capacity. The dual circularly polarized array antenna can simultaneously achieve left-handed circular polarization and right-handed circular polarization radiation, which lays the foundation for the multifunctional application of phased arrays. There are many wide-bandwidth and wide-angle circularly polarized phased array forms in the prior art, such as four-arm helical antennas. From the structure of this type of antenna, its radiation pattern can be used to widen the beam width of the antenna. However, the antenna has a high profile and strict requirements for processing and manufacturing. Therefore, it is obviously technically necessary to reduce the profile height of the antenna. Traditional microstrip antennas are widely used in phased arrays due to their small size, easy conformity with the carrier, easy circular polarization, and low profile. However, microstrip antennas are high-Q resonant antennas with narrow bandwidth. Therefore, how to improve the bandwidth and wide-angle scanning capability of circularly polarized patch antennas has become one of the urgent problems to be solved in circularly polarized phased array antenna technology. Most of the current circularly polarized phased arrays are single circularly polarized. The implementation of some dual circularly polarized phased arrays requires the use of linear polarization loaded four-port networks to achieve switching between the two circular polarizations through the characteristics of microstrip bridges, but this increases the complexity and profile height of the antenna structure. Overall, the circularly polarized phased array antennas in the prior art have the following problems: high profile; small working bandwidth; small beam width; most of them are single circularly polarized and cannot be polarization multiplexed.

[0003] Chengdu Weixun Technology Co., Ltd. disclosed a Ka dual circularly polarized antenna unit and a flat array antenna in its patent document "A Ka dual circularly polarized antenna unit and a flat array antenna" (application number 202310399656.4 application publication number CN 116231330A). The antenna is arranged from top to bottom in sequence through a radiation patch layer, a slot coupling layer, a waveguide transmission layer, and a feed network layer; a plurality of microstrip line structures are arranged on the radiation patch layer, and the microstrip line structure includes a first microstrip line and a second microstrip line, and the first microstrip line and the second microstrip line form a 90° phase difference of the orthogonal component of the electric field; the slot coupling layer includes a second substrate, and a source groove corresponding to the microstrip line structure is arranged on the second substrate. The slot coupling layer and the radiation patch layer are relatively displaced under the action of an external force, and the microstrip line structure corresponding to the source groove is switched between a left-handed circularly polarized microstrip line and a right-handed circularly polarized microstrip line through relative displacement. However, the antenna still has two shortcomings: first, it needs to generate relative displacement under the action of external force to adjust circular polarization, which has low flexibility and is easy to cause wear to the antenna. Second, the antenna has a high profile and complex structure. The two-layer microstrip structure increases the height and design complexity of the antenna, and increases the cost and processing difficulty of the antenna.

[0004] Xidian University disclosed a satellite-borne Ka-band circularly polarized unit and its corresponding phased array antenna in the patent document "A satellite-borne Ka-band circularly polarized antenna unit, antenna array and phased array" (application number 202211486446.0, application publication number CN 115810917 A). The phased array in the phased array antenna includes an upper radiation structure, an intermediate parasitic structure and a lower feeding structure. The radiation structure is composed of an upper metal patch, which can realize left-handed circularly polarized beam radiation. The feed is fed by the bottom metal probe and transmitted to the upper metal through coupling to achieve radiation. A circle of metalized vias is added around the radiating antenna to reduce the coupling effect between antennas. The phased array can achieve left-handed circular polarization effect and ±55° wide-angle scanning, but the antenna still has two shortcomings: First, the bottom metal probe feed is transmitted to the upper metal through coupling to achieve left-handed circular polarization radiation. It is a single circularly polarized phased array and cannot achieve dual circular polarization effect. Secondly, the antenna has a four-layer structure with a large number of layers, which increases the complexity of the antenna design and increases the cost and processing difficulty of the antenna. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to propose a low-profile dual circularly polarized Ka-band phased array antenna, aiming to solve the problems of high profile, complex structure and inability to polarization multiplex of traditional circularly polarized phased array antennas.

[0006] The technical idea for achieving the purpose of the present invention is: in view of the above-mentioned problems, the ka-band phased array antenna of the present invention adopts a two-layer dielectric plate structure, an upper parasitic metal patch, a middle metal radiation structure and a lower feeding structure. The feeding is transmitted from the lowest metal probe feeding to the upper metal through coupling to realize radiation, and a left-handed circularly polarized beam radiation is generated under the excitation of the left-handed circularly polarized port, and a right-handed circularly polarized beam radiation is generated under the excitation of the right-handed circularly polarized port. In order to reduce the coupling effect between antennas, a circle of metalized vias is added around the radiating antenna. By symmetrically designing the port position and the patch morphology, the antenna feeding structure and the metal patch structure are symmetrical, and the two ports respectively excite the radiating patch to generate left-handed circularly polarized radiation and right-handed circularly polarized radiation, eliminating the design of a complex feeding network layer, and directly connecting the radiating patch through the left-handed circularly polarized and right-handed circularly polarized feeding ports to realize polarization multiplexing of left-handed circularly polarized and right-handed circularly polarized. The Ka-band phased array achieves dual circular polarization without introducing other additional structures, which simplifies the antenna design process and solves the design problem that most circularly polarized phased array antennas in the prior art can only achieve single circular polarization and cannot reuse polarization. The antenna is composed of two layers of dielectric plates and does not require a microstrip network to achieve circular polarization, which reduces the antenna profile. The polarization switching can be achieved by adjusting the feed mode through the T / R components of the phased array, which solves the problems of high profile, complex structure and high processing cost of the phased array antenna.

[0007] The Ka-band phased array antenna of the present invention comprises N×N antenna arrays tightly arranged in a rectangular form, each antenna array is composed of 4×4 Ka-band dual circularly polarized antenna subarrays, wherein N is an integer greater than or equal to 2; the antenna units in each antenna subarray are composed of two layers of dielectric plates, the feeding structure and the metal patch structure are symmetrical, and the left-right circularly polarized feeding structure is directly connected to the metal patch structure.

[0008] Furthermore, each antenna subarray is composed of four ka-band dual circular polarization antenna units, which are arranged in a 90° rotation sequence with the first antenna unit as the reference point. A feed transmission structure is arranged under each antenna subarray.

[0009] Furthermore, each feeding transmission structure includes four left-hand circular polarization ports and four right-hand circular polarization ports, the left-hand and right-hand circular polarization ports are arranged in a cross form, and each port is connected to a phase shifter.

[0010] Furthermore, the rotation angle of the Ka-band dual circularly polarized antenna unit is equal to the phase of the phase shifter connected to its corresponding port; when working at the left-hand circularly polarized port, the rotation angle and phase of the four Ka-band dual circularly polarized antenna units are 0°, 90°, 180°, and 270°, respectively; when working at the right-hand circularly polarized port, the rotation angle and phase of the four Ka-band dual circularly polarized antenna units are 0°, 270°, 180°, and 90°, respectively.

[0011] Furthermore, the antenna unit in each antenna subarray is composed of two layers of dielectric plates, namely, a lower dielectric substrate, an intermediate semi-cured layer, and an upper dielectric substrate arranged in sequence from bottom to top. The lower dielectric substrate is provided with a left-handed circular polarization feeding structure in a mirror-symmetrical manner at the port position, and a first metallized blind hole and a second metallized blind hole penetrate the lower dielectric substrate; left-handed circular polarization is achieved when feeding through the first metallized blind hole, and right-handed circular polarization is achieved when feeding through the second metallized blind hole; metallized vias are provided in the lower dielectric substrate, the intermediate semi-cured layer, and the upper dielectric substrate, and the metallized vias penetrate the lower dielectric substrate, the intermediate semi-cured layer, and the upper dielectric substrate; the metallized vias are distributed in multiple equal intervals.

[0012] Furthermore, the horizontal cross-sections of the lower dielectric substrate, the middle semi-cured layer, and the upper dielectric substrate are regular quadrilaterals with equal areas.

[0013] Furthermore, the sum of the height of the lower dielectric substrate, the height of the middle semi-cured layer, and the height of the upper dielectric substrate is less than 2 mm.

[0014] Furthermore, a first upper metal ring and a first upper metal patch are printed on the upper surface of the lower dielectric substrate, and the two metal patches are symmetrical in structure. The metal patches are located in the first upper metal ring and are isolated from each other. A second upper metal ring and a second upper metal patch are printed on the upper surface of the upper dielectric substrate, and the two metal patches are symmetrical in structure. The second upper metal patch is located in the second upper metal ring and are isolated from each other. The first upper metal ring and the second upper metal ring are both regular quadrilateral closed frames, connected by metallized vias.

[0015] Furthermore, the first upper metal patch is composed of a first part, a second part, a third part, and a fourth part; the first part and the second part are both arrow-shaped, and the arrow direction is symmetrically arranged in the direction away from the center of the first dielectric substrate, and are connected at the tail, and the width of the connection part is less than the width of the widest part of the arrow. The third part and the fourth part are both composed of a rectangle and a semicircular ring, one side of the rectangle is connected to the arrow side of the first part, and the other side is connected to the semicircular ring. The fourth part is symmetrically arranged with the third part. The second upper metal patch is composed of a first part and a second part. The first part is an octagon with a hollow middle, and the second part is arranged in the hollow middle part of the first part, which is a standard regular quadrilateral.

[0016] Furthermore, the first upper metal patch is fed through the metallized blind hole of the feeding structure, and the second upper metal patch is coupled with the first upper metal patch for feeding and radiation, and left-hand circular polarization is achieved when feeding through the first metallized blind hole, and right-hand circular polarization is achieved when feeding through the second metallized blind hole, thereby realizing polarization multiplexing.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] First, the antenna of the present invention is symmetrically designed for port position and patch morphology, the antenna feeding structure and the metal patch structure are symmetrical, and the left-hand circular polarization feeding port is directly connected to the radiating patch, respectively exciting the patch to produce left-hand circular polarization and right-hand circular polarization, that is, realizing the regulation from single circular polarization to dual circular polarization, overcoming the defect that the prior art can only realize single circular polarization and it is difficult to realize polarization multiplexing, so that the present invention avoids the complex feeding network layer, and realizes the polarization multiplexing of left-hand circular polarization and right-hand circular polarization by directly connecting the radiating patch through the left-hand circular polarization and right-hand circular polarization feeding ports. While realizing dual circular polarization, the Ka-band phased array does not introduce other additional structures, simplifying the antenna design process.

[0019] Secondly, the antenna of the present invention is composed of two layers of dielectric plates, which eliminates the design of a complex feeding network layer, solves the problem of high complexity of the feeding network design and increased antenna profile height, and does not require an intermediate feeding network. The polarization switching can be achieved by directly adjusting the feeding mode through the T / R components of the phased array, which makes the antenna of the present invention have the advantages of simple structure and low profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a Ka-band dual circularly polarized phased array antenna according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of a Ka-band dual circularly polarized antenna subarray according to an embodiment of the present invention; wherein: Figure 2 (a) is the overall structure diagram of the antenna subarray; Figure 2 (b) is a schematic diagram of the left-right rotation port of the antenna subarray;

[0022] Figure 3 Schematic diagram of the Ka-band dual circular polarization antenna unit of the present invention; wherein, Figure 3 (a) is a schematic diagram of the overall structure of the antenna unit; Figure 3 (b) is a schematic side view of the antenna unit; Figure 3 (c) is a horizontal schematic diagram of the upper surface of the first dielectric substrate of the antenna unit; Figure 3 (d) is a horizontal schematic diagram of the upper surface of the second dielectric substrate of the antenna unit;

[0023] Figure 4This is the simulation result diagram of the Ka-band dual circular polarization antenna unit; among them, Figure 4 (a) is the standing wave ratio diagram of the Ka-band dual circularly polarized antenna unit; Figure 4 (b) is the axial ratio diagram of the Ka-band dual circularly polarized antenna unit; Figure 4 (c) is the radiation pattern of the Ka-band dual circularly polarized antenna unit at 29.3 GHz;

[0024] Figure 5 It is the axial ratio diagram of the Ka-band dual circularly polarized antenna subarray;

[0025] Figure 6 This is the simulation result diagram of the Ka-band dual circularly polarized phased array antenna; Figure 6 (a) is the radiation pattern of the antenna array at 29.3GHz 0°; Figure 6 (b) is the axial ratio diagram of the antenna array at 29.3GHz 0°; Figure 6 (c) is the radiation pattern of the antenna array at 29.3GHz 60°; Figure 6 (d) is the axial ratio diagram of the antenna array at 29.3GHz and 60°. DETAILED DESCRIPTION

[0026] The embodiments and effects of the present invention are further described below in conjunction with the accompanying drawings.

[0027] The antenna of the present invention is a dual circularly polarized phased array antenna operating in the millimeter wave band, and the number N of the dual circularly polarized radiating units in the Ka band is determined by the actual use of the antenna. The dual circularly polarized phased array antenna of the embodiment of the present invention adopts 8×8 Ka-band dual circularly polarized antenna radiating units, but those skilled in the art should understand that the dual circularly polarized phased array antenna in the millimeter wave band can also be combined by other numbers of dual circularly polarized antenna units. For example, 2×2, 4×4, 6×6, 8×8... The embodiments of the present invention are not limited to this.

[0028] Reference Figure 1 , the Ka-band dual circularly polarized phased array antenna structure of an embodiment of the present invention is further described.

[0029] The dual circularly polarized phased array antenna of the embodiment of the present invention adopts 64 Ka-band dual circularly polarized antenna radiating units, with 4×4 Ka-band dual circularly polarized antenna subarrays, according to Figure 1 The pattern shown is arranged in a rectangular array, forming a 64-element Ka-band dual circularly polarized phased array. Figure 1 The part indicated by the black arrow box in the middle is a Ka-band dual circularly polarized antenna subarray.

[0030] Reference Figure 2 , a subarray structure of the Ka-band dual circularly polarized antenna according to an embodiment of the present invention is further described.

[0031] Each antenna subarray 1 is composed of four ka-band dual circular polarization antenna units 11, 12, 13 and 14, which are arranged in a 90° rotation sequence with the antenna unit 11 as the reference point. A feed transmission structure 2 is arranged under each antenna subarray, such as Figure 2 (a) shown.

[0032] The feeding transmission structure 2 under each antenna subarray is composed of four left-hand circularly polarized ports 201 and four right-hand circularly polarized ports 202. The left-hand and right-hand circularly polarized ports are arranged in a cross form, and each port is connected to a phase shifter, such as Figure 2 (b) as shown.

[0033] In the described Ka-band dual circular polarization antenna subarray, the rotation angle of the antenna unit is equal to the phase of the phase shifter connected to its corresponding port; when the left-hand circular polarization port 201 is working, the rotation angles and phases of the antenna units 11, 12, 13 and 14 are 0°, 90°, 180° and 270° respectively. When the right-hand circular polarization port 202 is working, the rotation angles and phases of the antenna units 11, 12, 13 and 14 are 0°, 270°, 180° and 90° respectively. This phase setting makes the cross-polarization component generated by the antenna unit 11 and the cross-polarization component coupled by the antenna unit 12 and the antenna unit 14 cancel each other, and the cross-polarization component generated by the antenna unit 12 and the cross-polarization component coupled by the antenna unit 13 cancel each other, and the cross-polarization component generated by the antenna unit 13 and the cross-polarization component coupled by the antenna unit 14 cancel each other. Therefore, the embodiment of the present invention performs 90° sequential rotation array, which can enable the antenna to obtain a better main polarization component when working in a left-hand circular polarization or a right-hand circular polarization state.

[0034] refer to Figure 3 , the structure of the Ka-band dual circularly polarized antenna unit of an embodiment of the present invention is further described.

[0035] The antenna unit in each antenna subarray is composed of two layers of dielectric plates, which are arranged in sequence from bottom to top: a blue lower dielectric substrate 6 with a height h1=0.508 mm, an intermediate semi-cured layer 7 with a height h2=0.1 mm, and a blue upper dielectric substrate 8 with a height h3=1.016 mm. Figure 3 (a) and Figure 3 Indicated by the black arrow in (b).

[0036] Figure 3 The lower dielectric substrate 6 in (a) is mirror-symmetrically provided with a left-handed circular polarization feeding structure at the port position. The metalized blind holes 3 and 4 penetrate the lower dielectric substrate 6. When feeding through the metalized blind hole 3, left-handed circular polarization is realized. When feeding through the metalized blind hole 4, right-handed circular polarization is realized. Figure 3(a) Figure 3 (b) middle red short column, Figure 3 In (c), it is shown as a red dot with radius r1=0.1 mm.

[0037] The lower dielectric substrate 6, the middle semi-cured layer 7, and the upper dielectric substrate 8 are provided with metallized vias 5, which penetrate the upper substrate 8, the middle semi-cured layer 7, and the lower dielectric substrate 6. There are a plurality of metallized vias 5 distributed at equal intervals of l2=0.43mm, which can reduce the coupling between antenna units when arranging the array, such as Figure 3 (a) and Figure 3 (b) middle red long column, Figure 3 (c) and Figure 3 In (d), r0 is shown as a pink dot of 0.1 mm.

[0038] The horizontal cross-sections of the lower dielectric substrate 6, the middle semi-cured layer 7, and the upper dielectric substrate 8 are regular quadrilaterals with a side length of l0=4.85 mm and have equal areas.

[0039] The sum of the height of the lower dielectric substrate 6 , the height of the middle semi-cured layer 7 , and the height of the upper dielectric substrate 8 is less than 2 mm.

[0040] The Ka-band dual circular polarization antenna unit has a first upper metal ring 611 and a first upper metal patch 612 printed on the upper surface of the dielectric substrate 6. The two metal patches have symmetrical structures. The first upper metal patch 612 is located inside the first upper metal ring 611 and is isolated from each other. Figure 3 (c) The pink symmetrical structure and pink box are shown. The second upper metal ring 801 and the second upper metal patch 802 are printed on the upper surface of the upper dielectric substrate 8, and the two metal patches have symmetrical structures. The second upper metal patch 802 is located inside the second upper metal ring 801 and is isolated from each other. Figure 3 (d) shows a pink diamond ring structure and a pink square frame. The first upper metal ring 611 and the second upper metal ring 801 are both regular quadrilateral closed frames with a width of l2 = 0.2 mm, and are connected through a metallized via 5.

[0041] Reference Figure 3 (c) further describes the structure of the first upper metal patch 612 of the Ka-band dual circularly polarized antenna unit according to an embodiment of the present invention.

[0042] The first upper metal patch 612 is composed of a first portion 6121, a second portion 6122 and a third portion 6123, each of which has a length l6 and l7 of 1.71 mm. The first portion 6121 and the second portion 6122 are both arrow-shaped, and the arrows are symmetrically arranged in a direction away from the center of the first dielectric substrate 6, and are connected at the tail 6125. The width of the connection portion 6125 is smaller than the width of the widest part of the arrow, thereby forming two symmetrical concave portions 6126 with a length l8 = 0.45 mm and a width l9 = 0.3 mm at the connection. The third portion 6123 is composed of a length l 10 =0.87mm, width l 11 =0.8mm and a semicircular ring 61232 with radius r2 =0.25mm, one side of the rectangle 61231 is connected to the arrow side of the first part 6121, and the semicircular ring 61232 is connected to the opposite side of the one side of the rectangle 61231. The metallized blind hole 3 is projected at the center of the semicircular ring 61232. The fourth part 6124 is composed of a rectangle 61241 and a semicircular ring 61242, and the structural dimensions are consistent with those of the rectangle 61231 and the semicircular ring 61232 constituting the third part 6123.

[0043] Reference Figure 3 (d) further describes the structure of the second upper metal patch 802 of the Ka-band dual circularly polarized antenna unit according to an embodiment of the present invention.

[0044] The second upper metal patch 802 is a parasitic patch composed of a first part 8021 and a second part 8022. 8021 is an octagon with a hollow middle portion, wherein the side length of the octagon is l5=2.1 mm and the cut corner length is l3=0.5 mm. 8022 is the hollow middle portion of 8021, which is a standard regular quadrilateral with a side length of l4=1 mm.

[0045] The Ka-band dual circularly polarized antenna unit is mainly used as a radiation structure, and the first upper metal patch 612 is coupled and fed through the metallized blind hole 3 or the metallized blind hole 4 to realize circularly polarized beam radiation. The second upper metal patch 802 is coupled and fed with the first upper metal patch 612 for radiation. When feeding through the metallized blind hole 3, left-hand circular polarization is realized, and when feeding through the metallized blind hole 4, right-hand circular polarization is realized, thereby realizing polarization multiplexing.

[0046] The effect of the present invention is further described below in conjunction with simulation experiments:

[0047] 1. Simulation experimental conditions.

[0048] The simulation experiment of the present invention uses the Ansys Electronics Desktop software platform installed on computer hardware to complete the simulation of the Ka-band dual circular polarization phased array antenna.

[0049] 2. Analysis of simulation content and results.

[0050] The simulation experiment of the present invention is to simulate the unit, subarray and 8×8 element phased array of the Ka-band dual circular polarization phased array antenna of the embodiment of the present invention in the range of 23GHz to 35GHz. The simulation results are plotted into curve graphs, such as Figure 4 , Figure 5 , Figure 6 As shown. Among them, Figure 4 The simulation results of the Ka-band dual circularly polarized antenna unit standing wave ratio, axial ratio and radiation pattern at the center frequency of 29.3GHz are shown in the figure. Figure 5 This is the simulation result of the axial ratio effect for the Ka-band dual circularly polarized antenna subarray. Figure 6 The radiation scanning pattern of gain and axial ratio obtained when simulating an 8×8-element Ka-band dual circularly polarized phased array at phi=0° at the center frequency of 29.3GHz.

[0051] The effects of the present invention are further described below in conjunction with simulation diagrams.

[0052] Figure 4 (a) Figure 4 The horizontal axis in (b) represents the operating frequency of the antenna in GHz. Figure 4 The vertical axis in (a) represents the standing wave ratio. Figure 4 In (b), the ordinate represents the axial ratio in GHz. Figure 4 (a) Figure 4 In (b), the curve marked with a black straight line represents the relationship curve between the frequency and the standing wave ratio and the axial ratio when the antenna unit is operating in the right circular polarization state, and the curve marked with a red dotted line represents the relationship curve between the frequency and the standing wave ratio and the axial ratio when the antenna unit is operating in the left circular polarization state.

[0053] from Figure 4 (a) and Figure 4 (b) It can be seen that when the Ka-band dual circularly polarized antenna unit of the phased array works in left-hand circular polarization and right-hand circular polarization states, the impedance bandwidth with a standing wave ratio less than 2 is 24.83-33.75 GHz, and the axial ratio bandwidth with an axial ratio less than 3 dB is 29.21-33.03 GHz, which proves the consistency of the two circular polarization performances of the dual circularly polarized antenna unit of the present invention, and realizes polarization multiplexing through the symmetrical design of the port and patch morphology.

[0054] Figure 4 The horizontal axis in (c) represents the angle of the Theta plane in degrees, and the vertical axis represents the gain in dB. Figure 4The curve marked by the black straight line in (c) represents the curve of the change of the Theta surface gain with the Theta angle at the Phi = 0° surface, and the curve marked by the red dotted line represents the curve of the change of the axis ratio with the Theta angle at the Phi = 90° surface.

[0055] from Figure 4 (c) It can be seen that the 3dB beamwidth of the antenna unit at 29.3GHz in the Phi=0° plane and the Phi=90° plane is 109°, indicating that the antenna unit is suitable for beam scanning in a phased array.

[0056] Figure 5 The horizontal axis represents the operating frequency of the antenna in GHz, and the vertical axis represents the axial ratio in dB. Figure 5 The curve marked with a black straight line represents the relationship between the frequency and the axial ratio when the antenna subarray operates in the right-hand circular polarization state, and the curve marked with a red dotted line represents the relationship between the frequency and the axial ratio when the antenna subarray operates in the left-hand circular polarization state.

[0057] from Figure 5 It can be seen that when the Ka-band dual circularly polarized antenna subarray of the phased array works in left-hand circular polarization and right-hand circular polarization states, the axial ratio within the working frequency band is less than 0.2 dB, which proves that after the dual circularly polarized antenna units of the present invention are rotated 90° sequentially, the antenna obtains a better main polarization component when working in left-hand circular polarization or right-hand circular polarization state.

[0058] Figure 6 (a) Figure 6 (b) Figure 6 (c) Figure 6 The horizontal axis in (d) represents the angle of the Theta plane, with the unit of deg. Figure 6 (a) Figure 6 The vertical axes in (c) represent the gain, Figure 6 (b) Figure 6 The ordinate of (d) represents the axial ratio, and the unit is dB. Figure 6 The curve marked with a red straight line in the figure represents the change curve of the gain or axial ratio with the Theta angle when the beam is pointed at 0°, and the curve marked with a blue dotted line represents the change curve of the gain or axial ratio with the Theta angle when the beam is pointed at 60°.

[0059] from Figure 6 It can be seen that: the phased array of the present invention points to 0° at 29.3GHz, the Ka-band dual circularly polarized phased array antenna has a beam width of 13°, a sidelobe level of 9.3dB, and an axial ratio of less than 3dB. When the phased array of the present invention scans 60° at 29.3GHz, the Ka-band circularly polarized phased array antenna has a beam width of 24° when the beam points to 60°, and an axial ratio of less than 3dB.

[0060] The above simulation experiments show that: the present invention adopts a double-layer dielectric plate and a symmetrical design of the structure, thereby solving the problem that the current circularly polarized phased array antenna has a high cross-section and a complex structure and cannot realize polarization multiplexing; since the design of the feeding network is omitted, the radiating patch is directly connected through the left and right ports to excite left-hand circular polarization and right-hand circular polarization, so the overall cross-section of the antenna is low; due to the design of the antenna shape and the introduction of parasitic patches in addition to the main radiating patch, circular polarization is formed through the joint action of the two patches; the Ka-band dual circularly polarized antenna unit has consistent left and right circular polarization performance and a wider beam width, and can be used for beam scanning of the Ka-band dual circularly polarized phased array.

[0061] The specific embodiments of the present invention do not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A low-profile dual circularly polarized Ka-band phased array antenna, comprising N×N antenna arrays closely arranged in a rectangular form, each antenna array being composed of 4×4 Ka-band dual circularly polarized antenna subarrays, wherein: N is an integer greater than or equal to 2; it is characterized in that the antenna units in each antenna subarray are composed of two layers of dielectric plates, the feeding structure and the metal patch structure are symmetrical, and the left-right circularly polarized feeding structure is directly connected to the metal patch structure.

2. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 1, characterized in that: Each antenna subarray is composed of four ka-band dual circular polarization antenna units (11), (12), (13) and (14), which are arranged in a 90° rotation sequence with the antenna unit (11) as a reference point; and a feeding transmission structure (2) is arranged under each antenna subarray.

3. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 2, characterized in that: The feeding transmission structure (2) comprises four left-hand circular polarization ports and four right-hand circular polarization ports, the left-hand circular polarization ports and the right-hand circular polarization ports are arranged in a cross form, and each port is connected to a phase shifter.

4. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 2, characterized in that: The rotation angle of the Ka-band dual circular polarization antenna unit is equal to the phase of the phase shifter connected to its corresponding port; when the left-hand circular polarization port is working, the rotation angle and phase of the antenna units (11), (12), (13) and (14) are 0°, 90°, 180° and 270° respectively; when the right-hand circular polarization port is working, the rotation angle and phase of the antenna units (11), (12), (13) and (14) are 0°, 270°, 180° and 90° respectively.

5. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 1, characterized in that: The antenna units in each antenna subarray are composed of two layers of dielectric plates, namely, a lower dielectric substrate (6), an intermediate semi-cured layer (7), and an upper dielectric substrate (8) which are arranged in sequence from bottom to top; the lower dielectric substrate (6) is provided with a left-handed circular polarization feeding structure in a mirror-symmetrical manner at the port position, and the metallized blind holes (3) and (4) penetrate the lower dielectric substrate (6), and when feeding through the metallized blind hole (3), left-handed circular polarization is achieved, and when feeding through the metallized blind hole (4), right-handed circular polarization is achieved; and a plurality of metallized vias (5) distributed at equal intervals penetrate the lower dielectric substrate (6), the intermediate semi-cured layer (7), and the upper dielectric substrate (8).

6. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 5, characterized in that: The horizontal cross-sections of the lower dielectric substrate (6), the middle semi-cured layer (7), and the upper dielectric substrate (8) are regular quadrilaterals with equal areas.

7. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 5, characterized in that: The sum of the height of the lower dielectric substrate (6), the height of the intermediate semi-cured layer (7), and the height of the upper dielectric substrate (8) is less than 2 mm.

8. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 5, characterized in that: The upper surface of the lower dielectric substrate (6) is printed with a first upper metal ring (611) and a first upper metal patch (612), and the two metal patches are symmetrical in structure; the metal patch (612) is located inside the first upper metal ring (611) and is isolated from each other; the upper surface of the upper dielectric substrate (8) is printed with a second upper metal ring (801) and a second upper metal patch (802), and the two metal patches are symmetrical in structure; the second upper metal patch (802) is located inside the second upper metal ring (801) and is isolated from each other; the first upper metal ring (611) and the second upper metal ring (801) are both regular quadrilateral closed frames and are connected via the metallized via (5).

9. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 8, characterized in that: The first upper metal patch (612) is composed of a first part (6121), a second part (6122), a third part (6123), and a fourth part (6124); the first part (6121) and the second part (6122) are both arrow-shaped, and the arrow direction is symmetrically arranged in a direction away from the center of the first dielectric substrate (6), and are connected at the tail, and the width of the connection part is smaller than the width of the widest part of the arrow; the third part (6123) and the fourth part (6124) are both composed of a rectangle and a semicircular ring, one side of the rectangle is connected to the arrow side of the first part, and the other side is connected to the semicircular ring; the fourth part (6124) is symmetrically arranged with the third part (6123); the second upper metal patch (802) is composed of a first part (8021) and a second part (8022); the first part (8021) is an octagon with a hollow middle, and the second part (8022) is the hollow middle part of the first part (8022), which is a standard regular quadrilateral.

10. The low-profile dual circularly polarized Ka-band phased array antenna according to claim 9, characterized in that: The first upper metal patch (612) is fed through the metallized blind hole (3) or (4) of the feeding structure, and the second upper metal patch (802) is coupled with the first upper metal patch (612) for feeding and radiation. When feeding through the metallized blind hole (3), left-hand circular polarization is achieved, and when feeding through the metallized blind hole (4), right-hand circular polarization is achieved, thereby achieving polarization multiplexing.

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