Directional diagram reconfigurable circularly polarized array antenna

Abstract

The invention discloses a directional diagram reconfigurable circular polarization array antenna, which comprises a plurality of antenna units distributed according to a matrix rule, and is characterized in that each antenna unit comprises a radiation patch, a first metal floor, a first direct current bias circuit, a second direct current bias circuit, a second metal floor and a 90-degree phase shifter which are sequentially arranged from top to bottom, wherein the radiation patch and the first metal floor are respectively etched on the upper surface and the lower surface of the first dielectric substrate, the first direct current bias circuit and the second direct current bias circuit are respectively etched on the upper surface and the lower surface of the second dielectric substrate, and the second metal floor and the 90-degree phase shifter are respectively etched on the upper surface and the lower surface of the third dielectric substrate. Pressing the three layers of dielectric substrates together by using two prepregs; the antenna has the advantages that antenna side lobes are reduced, and antenna efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of array antenna technology, and more specifically to a pattern-reconfigurable circularly polarized array antenna. Background Technology

[0002] In array antenna design, sequential rotating feed is commonly used to achieve broadband circularly polarized radiation, such as the low-profile dual-circularly polarized Ka-band phased array antenna disclosed in Chinese Patent Publication No. CN119627418A. The advantage of this method is that it can use elliptical polarized antenna elements with poor axial ratio performance, or even linearly polarized antenna elements, to design a circularly polarized array antenna. However, its disadvantages are also obvious. To achieve circularly polarized radiation, the output phases of the feed ports of each 2×2 subarray must differ by -90° or 90° sequentially, requiring a large wiring space and increasing the design difficulty of the feed network. Furthermore, when the array antenna performs spatial beam scanning, the scanning phase distribution of the array surface is usually periodic or quasi-periodic. This phase arrangement has a certain spatial symmetry, which generates grating lobes in the far-field radiation pattern, deteriorating the main lobe scanning characteristics of the antenna, increasing main lobe energy leakage, and reducing antenna efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is that the existing array antenna has the problems of deteriorating the main lobe scanning characteristics, increasing the main lobe energy leakage, and reducing the antenna efficiency.

[0004] This invention solves the above-mentioned technical problems through the following technical means: a pattern-reconfigurable circularly polarized array antenna, comprising multiple antenna elements distributed in a matrix pattern, each antenna element comprising, from top to bottom, a radiating patch, a first metal ground plane, a first DC bias circuit, a second DC bias circuit, a second metal ground plane, and a 90-degree phase shifter, wherein the radiating patch and the first metal ground plane are respectively etched on the upper and lower surfaces of a first dielectric substrate, the first DC bias circuit and the second DC bias circuit are respectively etched on the upper and lower surfaces of a second dielectric substrate, and the second metal ground plane and the 90-degree phase shifter are respectively etched on the upper and lower surfaces of a third dielectric substrate, and the three dielectric substrates are laminated together using two prepregs. Each antenna element has a first diode and a second diode integrated on its radiating patch. The cathode of the first diode and the anode of the second diode are connected to the second DC bias circuit and the 90-degree phase shifter through a first metallized via. The anode of the first diode and the cathode of the second diode are connected to the first metal ground plane through a microstrip line and the second metallized via. Each element's 90-degree phase shifter has a third diode and a fourth diode integrated on its radiating patch. The cathodes of the third diode and the fourth diode are connected to the second metal ground plane through a microstrip line and the fourth metallized via. The anodes of the third diode and the fourth diode are connected to the first DC bias circuit through another microstrip line and the third metallized via.

[0005] This invention achieves reconfigurable radiation patterns for the entire antenna array by independently controlling the phase state of each diode on the antenna element. By introducing a geometric pre-phase on the first-layer antenna radiating patch, combined with the reconfigurable phase introduced by the diodes, a 3dB axial ratio bandwidth can be enhanced, while simultaneously reducing antenna sidelobes and improving antenna efficiency. The first and second DC bias circuits are used to control the voltage states of the radiating patch and the diodes.

[0006] Furthermore, the structure of the 90-degree phase shifter is as follows: a grid-like metal region is etched on the lower surface of the third dielectric substrate. This metal region includes a main line and a secondary line. The main line is the connection line between the negative terminals of the third diode and the fourth diode. The two ends of the main line are respectively provided with a first port and a second port, serving as a feed port and a receive port. The secondary line is a line parallel to the main line, with both ends set in a stepped shape. The negative terminal of the third diode is perpendicularly connected to the main line through a branch line, and the negative terminal of the fourth diode is perpendicularly connected to the main line through another branch line. The positive terminal of the third diode is connected to the secondary line, and the positive terminal of the fourth diode is connected to the secondary line. A microstrip line is connected to both the main line and the secondary line.

[0007] Furthermore, the main line is divided into three parts: a middle section, a first section and a second section connected to the middle section, and a 100 pF lumped capacitor is connected between the first section and the middle section, as well as between the second section and the middle section. The first section and the second section have the same width but are narrower than the middle section. The ends of the first section and the second section are respectively provided with a first port and a second port, which serve as a power supply port and a receiving port.

[0008] Furthermore, the optimization method for the 90-degree phase shifter is as follows:

[0009] The center operating frequency of the 90-degree phase shifter was set to 10 GHz. With the optimization goal of minimizing insertion loss and maximizing phase shifting performance, the linewidths of the first and second segments of the main line were adjusted. w 1. Line width in the middle section w 3. Branch line width w 2 and length l 2. Line width in the middle area of ​​the sub-line w 4. Width of the stepped structure at both ends of the sub-line w 5 and length l 1. The final determined structural parameters of the phase shifter are as follows: l 1 = 2.6 l 2 = 3.1, l 3 = 3.5 w 1 = 1.08 w 2 = 0.6, w 3 = 1.5w 4 = 0.8 w 5 = 3.25, unit: mm.

[0010] Furthermore, the structure of the radiating patch of the antenna unit is as follows: a rectangular metal region is etched on the upper surface of the first dielectric substrate, one side of the rectangular metal region is connected to a microstrip line, the two diagonals of the rectangular metal region are cut off, an H-shaped insulating region is etched in the middle of the rectangular metal region, the center of the H-shaped insulating region is a rectangular metal sheet, the gap between the rectangular metal sheet and the upper part of the H-shaped insulating region is connected to the positive and negative terminals of the first diode, and the gap between the rectangular metal sheet and the lower part of the H-shaped insulating region is connected to the positive and negative terminals of the second diode.

[0011] Furthermore, the optimization method for the antenna element is as follows: The center operating frequency of the antenna element was set to 10 GHz, the operating polarization was determined to be left-hand circular polarization, and the thickness of the first dielectric substrate was adjusted to optimize the antenna element by minimizing insertion loss and maximizing phase shift performance. h 1. Thickness of the second dielectric substrate h 2. Thickness of the third dielectric substrate h 3. Width of the entire array antenna p The width of the rectangular metal area of ​​the radiating patch pp The length of the hypotenuse after cutting off the diagonal of the rectangular metal region of the radiating patch. s The height of the H-shaped insulation zone ps The outer diameter of the first metallized via d v1 Outer diameter of the first metal ground plane anti-solder pad d k1 The outer diameter of the third metallized via connecting the phase shifter and the first DC bias circuit. d v2 And the outer diameter of the anti-pad associated with the first DC bias circuit on the second metal floor. d k2 Through simulation and optimization, the structural parameters of the antenna element were finally determined as follows: h 1 = 2, h 2 = 0.25 h 3 = 0.5 s = 2.74, ps = 3.9, pp = 6.64, d v1 = 0.6, d k1 = 2.4, d v2 = 0.4, d k2 = 2,p = 14.5, unit mm.

[0012] Furthermore, the radiating patch structure of the array antenna has an initial geometric pre-phase, setting the initial phase of the left-hand circular polarization of the antenna element to the illumination phase of the spherical wave feed at a focal length F = 55 mm. Radiation patches based on phase Determine their respective rotation angles, where the discrete phase required to be provided by the radiating patch in the m-th row and n-th column of the array antenna. Calculated by the following formula:

[0013] In the formula, For the gradient phase required for beam scanning, This indicates that the function value is rounded. Indicates taking the remainder. Indicating the initial geometric prephase, the far-field electric field of the antenna... ( , The calculation is as follows:

[0014]

[0015] in, The pitch angle representing beam deflection. Indicates the azimuth angle of beam deflection. This is the beamwidth factor of the antenna. This indicates the row number of antenna elements in the array antenna. This indicates the number of columns of antenna elements in the array antenna. Represents the imaginary unit. This represents the wave number of electromagnetic waves in free space. This represents the ( ) determined by the array geometry and the direction of arrival. m , n The normalized path difference of each array element relative to the array phase center. Indicates unit along x Dimensions in the axial direction Indicates unit along y Dimensions in the axial direction.

[0016] Furthermore, when each antenna unit is in operation, both the first and second metal ground planes are connected to DC ground. The cutoff and conduction of the first and second diodes are controlled by signals on the first DC bias circuit, and the cutoff and conduction of the third and fourth diodes are controlled by signals on the second DC bias circuit.

[0017] Furthermore, the first dielectric substrate is an F4B with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 2 mm; the second dielectric substrate is an F4B with a relative permittivity of 2.2, a loss tangent of 0.001, and a thickness of 0.25 mm; and the third dielectric substrate is an F4B with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 0.5 mm.

[0018] Furthermore, all four diodes are PIN diodes, and all are model MADP-000907-14020.

[0019] The advantages of this invention are: (1) By adjusting the state of each diode on the antenna element, the phase state of each element on the array can be independently controlled, thereby achieving reconfigurable radiation pattern of the entire array. By introducing a geometric pre-phase on the first layer of antenna radiating patch, and cooperating with the reconfigurable phase introduced by the diode, the axial ratio bandwidth can be enhanced by 3dB, while reducing antenna sidelobes and improving antenna efficiency. The first DC bias circuit and the second DC bias circuit are used to control the voltage state of the radiating patch and the diode.

[0020] (2) The array antenna of the present invention is controlled by the initial geometric pre-phase and the 2-bit transmission phase. By reasonably configuring the initial phase of the main polarization and the cross polarization, good circular polarization radiation and two-dimensional beam scanning performance are achieved, so that the reconfigurable circular polarization array antenna has broadband axial ratio performance and low sidelobe characteristics.

[0021] (3) The diode of the present invention acts as a "radio frequency switch," directly resetting the radiation phase state of the unit by changing the unit current path or boundary conditions. The array pattern is the result of the coherent superposition of the electric fields of each unit. By independently setting the phase of each unit, the interference pattern of the array is set. By programming to change the phase distribution of all units, the entire radiation pattern is reconstructed.

[0022] (4) Traditional circular polarization technology is usually achieved through sequential rotation. In the traditional sequential rotation method, the phase sequence difference at the feed port of the 2×2 subarray is 90° or -90°, which usually requires a large wiring space and increases the design difficulty of the feed network. In this invention, there is no need for complex feed network design; the effect superior to the traditional method can be achieved simply by reasonably configuring the geometric pre-phase of the array surface. This greatly reduces the complexity of the feed network design. At the same time, it does not require a large wiring space, reducing the size of the antenna. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the actual structure of the pattern-reconfigurable circularly polarized array antenna provided in an embodiment of the present invention; Figure 2 A schematic diagram of the unit structure of a pattern-reconfigurable circularly polarized array antenna provided in an embodiment of the present invention; Figure 2 The left side shows a cross-sectional view of the unit structure of the array antenna. Figure 2 The right side shows an exploded view of the unit structure of the array antenna; Figure 3 (a) is a schematic diagram of the radiating structure on the first dielectric substrate and the first metal ground plane in the antenna unit provided in an embodiment of the present invention; Figure 3 (b) is a schematic diagram of the structure of the second metal ground plane and the 90° phase shifter on the third dielectric substrate in the antenna unit provided in the embodiment of the present invention; Figure 3 (c) is a schematic diagram of the structure of the first DC bias circuit and the second DC bias circuit on the second dielectric substrate in the antenna unit provided in the embodiment of the present invention; Figure 4 (a) is a schematic diagram of the 90° phase shifter structure provided in an embodiment of the present invention; Figure 4 (b) A schematic diagram of the insertion loss of the 90° phase shifter provided in an embodiment of the present invention; Figure 4 (c) is a schematic diagram of the phase shifting performance of the 90° phase shifter provided in an embodiment of the present invention; Figure 5 (a) is a schematic diagram of the impedance matching characteristics of the antenna element provided in an embodiment of the present invention; Figure 5 (b) is a schematic diagram of the transmission amplitude characteristics of the left-hand circularly polarized (LHCP) wave of the antenna element provided in the embodiment of the present invention; Figure 5 (c) is a schematic diagram of the right-hand circularly polarized (RHCP) wave transmission amplitude characteristics of the antenna element provided in the embodiment of the present invention; Figure 5 (d) is a schematic diagram of the left-hand circularly polarized (LHCP) wave transmission phase characteristics of the antenna element provided in the embodiment of the present invention; Figure 6 The transmission amplitude and phase of the left-hand circularly polarized wave provided by the antenna element in the embodiments of the present invention as a function of rotation angle in states 1 to 4. The curves showing the changes; where State1 to State4 correspond to the four different working states listed in Table 1. Figure 7 (a) The initial geometric prephase of the array antenna provided in the embodiment of the present invention is configured for left-hand circularly polarized waves; Figure 7 (b) The initial geometric prephase of the array antenna provided in the embodiment of the present invention is configured for right-hand circularly polarized waves; Figure 8 (a) is a schematic diagram of the radiating patch and feed network structure of the array antenna provided in an embodiment of the present invention; Figure 8 (b) Normalization of the left-hand circularly polarized 0° beam and the right-hand circularly polarized beam of the array antenna provided in the embodiments of the present invention. UV Planar orientation diagram; Figure 8 (c) The normalized two-dimensional radiation pattern and axial ratio performance of the array antenna with left-hand circular polarization 0° beam and right-hand circular polarization provided in the embodiments of the present invention; Figure 9 (a) is a schematic diagram of the radiating patch structure of a conventional circularly polarized beam scanning array antenna provided in an embodiment of the present invention; Figure 9 (b) Normalization of the left-hand circularly polarized 0° beam and the right-hand circularly polarized beam of the conventional circularly polarized beam scanning array antenna provided in the embodiments of the present invention. UV Planar orientation diagram; Figure 9 (c) The normalized two-dimensional radiation pattern of the left-hand circularly polarized 0° beam and the right-hand circularly polarized beam of the conventional circularly polarized beam scanning array antenna provided in the embodiment of the present invention; Figure 9 (d) The axial ratio characteristics of the left-hand circularly polarized 0° beam and the right-hand circularly polarized beam of the conventional circularly polarized beam scanning array antenna provided in the embodiment of the present invention; Figure 10 At 10 GHz, two contrast array antennas provided in embodiments of the present invention xoz The normalized radiation patterns of each scanning beam are shown. The upper left portion (marked by the black dashed box) of each sub-figure is the two-dimensional radiation pattern, the upper right portion is the 2-bit phase distribution of the two comparison antennas (marked by the red dashed box), and the lower half is the radiation pattern of the two comparison antennas. UV Planar radiation pattern (the area marked by the blue dashed box; numbers 1 and 2 represent the left and right circular polarization of Antenna 1, respectively; numbers 3 and 4 represent the left and right circular polarization of Antenna 2, respectively). Figure 11 This invention provides normalized radiation patterns of the scanning beams of two contrast array antennas at 10 GHz in the yoz plane. The upper left portion (marked by the black dashed box) of each sub-figure is a two-dimensional radiation pattern, the upper right portion is the 2-bit phase distribution of the two contrast antennas (marked by the red dashed box), and the lower half is the radiation pattern of the two contrast antennas. UV Planar radiation pattern (the area marked by the blue dashed box; numbers 1 and 2 represent the left and right circular polarization of Antenna 1, respectively; numbers 3 and 4 represent the left and right circular polarization of Antenna 2, respectively). Figure 12 The axial ratio performance of each scanning beam at 10 GHz for two contrast array antennas provided in the embodiments of the present invention (red and green lines correspond to Antenna 1 and Antenna 2, respectively). Figure 13 Beam scanning of two contrast array antennas provided in embodiments of the present invention S The left figure shows the parametric simulation results. xoz The result is shown in the right figure. yoz Surface results. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0025] This invention provides a pattern-reconfigurable circularly polarized array antenna for enhancing 3 dB axial ratio bandwidth while reducing sidelobes. This design combines wide axial ratio characteristics, low sidelobes, and pattern reconfigurability. In highly integrated and complex electromagnetic applications, it enables high-performance dynamic control of the spatially circularly polarized beam.

[0026] This invention provides a pattern-reconfigurable circularly polarized array antenna, such as... Figure 1 The diagram shown is a schematic of the structure of the circularly polarized array antenna. The array antenna has a 6-layer PCB structure, including: the first layer antenna radiation structure (i.e., radiation patch 1), the second layer radiation structure metal ground (referred to as the first metal ground 2), the third layer radiation patch 1 DC bias network (referred to as the first DC bias circuit 3), the fourth layer phase-shifting structure DC bias network (referred to as the second DC bias circuit 4), the fifth layer phase-shifting structure metal ground (referred to as the second metal ground 5), and the sixth layer phase-shifting structure and equal amplitude and in-phase T-type power divider feed network. In this embodiment, the phase-shifting structure is a 90-degree phase shifter 6.

[0027] like Figure 2The diagram shows a schematic of the unit structure of the circularly polarized array antenna. The unit is composed of six layers of metal structure, three layers of dielectric substrate, and two layers of prepreg 10 stacked together. The six layers of metal structure, from top to bottom, are: a radiating patch 1, a first metal ground plane 2, a first DC bias circuit 3, a second DC bias circuit 4, a second metal ground plane 5, and a 90-degree phase shifter 6. The radiating patch 1 and the first metal ground plane 2 are respectively etched onto the upper and lower surfaces of the first dielectric substrate 7 (F4B with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 2 mm). The first DC bias circuit 3 and the second DC bias circuit 4 are respectively etched onto the upper and lower surfaces of the second dielectric substrate 8 (F4B with a relative permittivity of 2.2, a loss tangent of 0.001, and a thickness of 0.25 mm). The second metal ground plane 5 and the 90-degree phase shifter 6 are respectively etched onto the third dielectric substrate 9 (F4B with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 0.5 mm). Two 0.1mm thick prepregs 10 are placed between the first metal ground plane 2 and the first DC bias circuit 3, and between the second DC bias circuit 4 and the second metal ground plane 5, respectively, on the top and bottom surfaces of the F4B (mm thick). This bonding of the three dielectric substrates together is achieved by bonding the prepregs 10 together. The prepregs 10 also serve to isolate the metal ground plane and the DC bias circuits. Both DC bias circuits employ a λ / 4 high-resistivity line + fan-shaped stub structure, where λ is the wavelength. The edges of the fan-shaped stubs are open-circuited, and after λ / 4 transformation, they are equivalent to a short circuit at the center. The center is then connected to the high-resistivity line to form an open circuit in the main path, preventing RF signals from entering the DC channel. See details... Figure 3 (c) An antenna element is designed using a cascaded phase-shifting method to achieve 2-bit phase reconfigurability. Specifically, 1-bit phase modulation is achieved using the radiating patch 1, and an additional 90-degree phase shifter 6 is cascaded to achieve 2-bit phase modulation. As shown in Figure 3(a), each element's radiating patch 1 integrates two PIN diodes placed in the same direction. The cathode of the first diode and the anode of the second diode are connected to the first metallized via. Figure 3 (c) The center of the second DC bias circuit 4 is connected to the 90-degree phase shifter 6 located at the bottom of the unit (a diameter is provided on both the first metal ground plate 2 and the second metal ground plate 5). d k1The first circular groove is used for the first metallized via to pass through without contacting it. The positive terminal of the first diode and the negative terminal of the second diode are connected to the first metal ground plane 2 through a high-impedance microstrip line and the second metallized via. As shown in Figure 3(b), the designed 90-degree phase shifter 6 is a typical load-line phase shifter. Each unit of the 90-degree phase shifter 6 integrates a third diode and a fourth diode. The negative terminals of the third diode and the fourth diode are connected to the second metal ground plane 5 through a high-impedance microstrip line and the fourth metallized via. The positive terminals of the third diode and the fourth diode are connected to the second metal ground plane 5 through another high-impedance microstrip line and the third metallized via. Figure 3 (c) The center of the first DC bias circuit 3 (a diameter is opened on the second metal ground plate 5) d k2 The second circular slot is for the third metallized via to pass through without contacting it. All four PIN diodes are MADP-000907-14020. To isolate DC signals from the first DC bias circuit 3 and adjacent units, two 100 pF lumped capacitors are connected across the main line of the 90-degree phase shifter 6. Figure 3 (b) Purple elements 5 and 6), the main line is the connection line between the negative terminals of the third diode and the fourth diode. The two ends of the main line are the first port and the second port, which serve as the feed port and the receiving port, respectively. Specifically, the structure of the 90-degree phase shifter 6 is that a grid-shaped metal area is etched on the lower surface of the third dielectric substrate 9. The metal area includes a main line and a sub-line. The main line is the connection line between the negative terminals of the third diode and the fourth diode. The two ends of the main line are respectively provided with the first port and the second port, which serve as the feed port and the receiving port. The sub-line is a line that is relatively parallel to the main line. The two ends of the sub-line are set as a stepped shape. The negative terminal of the third diode is perpendicularly connected to the main line through a branch line. The negative terminal of the fourth diode is perpendicularly connected to the main line through another branch line. The positive terminal of the third diode is connected to the sub-line. The positive terminal of the fourth diode is connected to the sub-line. A microstrip line is connected to both the main line and the sub-line. The main line consists of three parts: a middle section, a first section connected to the middle section, and a second section. A 100 pF lumped capacitor is connected between the first section and the middle section, and between the second section and the middle section. The first and second sections have the same width but are narrower than the middle section. The ends of the first and second sections are respectively provided with a first port and a second port, serving as a power supply port and a receiving port. During unit operation, both the first metal ground plate 2 and the second metal ground plate 5 are connected to DC ground. Therefore, the cutoff and conduction of the first and second diodes are independently controlled by signals on the first DC bias circuit 3, and the cutoff and conduction of the third and fourth diodes are independently controlled by signals on the second DC bias circuit 4.

[0028] The simulation setup of the 90-degree phase shifter 6 is shown in Figure 4(a). The first and second ports of the 90-degree phase shifter 6 are the feed port and the receive port, respectively. To fully consider the periodic effect after the antenna element array is assembled, the following settings are used: x direction and y The boundary conditions for the direction are set to unit cell. z The directional boundary conditions are set to open (add space). The center operating frequency of the phase shifter is set to 10 GHz, and simulations and optimizations are performed to minimize insertion loss and maximize phase shift performance. The linewidths of the first and second segments of the main line are adjusted. w 1. Line width in the middle section w 3. Branch line width w 2 and length l 2. Line width in the middle area of ​​the sub-line w 4. Width of the stepped structure at both ends of the sub-line w 5 and length l 1. The final determined structural parameters of the phase shifter are (unit: mm): l 1 = 2.6 l 2 = 3.1, l 3 = 3.5 w 1 = 1.08 w 2 = 0.6, w 3 = 1.5 w 4 = 0.8 w 5 = 3.25. Figure 4 (b) and (c) show the insertion loss and phase shift performance curves of the phase shifter. It can be seen that at the center operating frequency of 10 GHz, when the diode is on and off, the insertion loss is -0.4 dB and -0.9 dB, respectively, and the phase difference between the two states is 86°, which can basically meet the 90° phase shift requirement.

[0029] Continue reading Figure 2 as well as Figure 3(a) The structure of the radiating patch 1 of the antenna unit is as follows: a rectangular metal region is etched on the upper surface of the first dielectric substrate 7. One side of the rectangular metal region is connected to a microstrip line. The two diagonals of the rectangular metal region are cut off. An H-shaped insulating region is etched in the middle of the rectangular metal region. A rectangular metal sheet is located at the center of the H-shaped insulating region. The gap between the rectangular metal sheet and the upper part of the H-shaped insulating region connects the positive and negative terminals of the first diode. The gap between the rectangular metal sheet and the lower part of the H-shaped insulating region connects the positive and negative terminals of the second diode. The center operating frequency of the antenna unit is set to 10 GHz, the operating polarization is determined to be left-hand circular polarization, and the antenna unit is optimized to minimize insertion loss and maximize phase shift performance. The thickness of the first dielectric substrate 7 is adjusted accordingly. h 1. Thickness of the second dielectric substrate 8 h 2. Thickness of the third dielectric substrate 9 h 3. Width of the entire array antenna p The width of the rectangular metal area of ​​the radiating patch 1 pp The length of the hypotenuse after cutting off the diagonal of the rectangular metal region of the radiating patch 1 s The height of the H-shaped insulation zone ps The outer diameter of the first metallized via d v1 The outer diameter of the first metal ground plate 2 anti-soldering pad d k1 The outer diameter of the third metallized via connecting the phase shifter and the first DC bias circuit 3 d v2 and the outer diameter of the anti-soldering pad on the second metal ground plate 5 associated with the first DC bias circuit 3 d k2 Simulation and optimization were performed to ultimately determine... Figure 3 The structural parameters of the middle unit are (unit: mm): h 1 = 2, h 2 = 0.25 h 3 = 0.5 s =2.74, ps = 3.9, pp = 6.64, d v1 = 0.6, d k1 = 2.4, d v2 = 0.4, d k2 = 2, p = 14.5. The signal radiation process of the antenna is as follows: the radio frequency signal from... Figure 3(b) The signal energy is input at the left port of the 90° phase shifter. After phase shifting by the phase shifter, the signal energy is transmitted to the radiating patch 1 through the metal through hole at the right corner port. The radiating patch 1 then radiates electromagnetic waves into space.

[0030] Table 1 summarizes the diode states, relative phases, and DC voltage signals corresponding to different operating states of the antenna element. The diode states "0" and "1" represent the diode being cut off and turned on, respectively. The relative phase is referenced to the phase value of State 1 (i.e., its phase is recorded as 0°). The DC voltage control signals "0" and "1" represent -2.5 V and +2.5 V DC voltages, respectively.

[0031] Table 1. Diode state, relative phase, and DC voltage signal corresponding to different operating states of the unit.

[0032] The amplitude of the port reflection coefficient obtained from the simulation is as follows Figure 5 As shown in (a), the results show the | S 11 The impedance bandwidth of |<-10 dB is relatively narrow, with State 3's |S11|<-10 dB impedance bandwidth covering only 9.15-10.2 GHz (red shaded area in the figure). Figure 5 (b) The transmission coefficient amplitude for left-hand circular polarization is given, and the cell transmission coefficient amplitude is above -2 dB in all operating modes within the range of 9.6–10.3 GHz as shown in blue shading. Figure 5 (c) gives the transmission coefficient amplitude for right-hand circular polarization, as shown in purple shading, within the range of 9.61–10.48 GHz, where the cell transmission coefficient amplitude is below -10 dB in all operating modes. Figure 5 (d) shows the transmission coefficient phase of the left-hand circularly polarized wave, demonstrating that the unit achieves essentially 2-bit phase modulation within the 9-11 GHz range. Furthermore, the phase shift generated by the unit's 90-degree phase shifter 6 is the transmission phase shift. The radiating patch 1 in Figure 3(a) is wound around... z Rotation angle of axis counterclockwise Its transmission coefficient 21 The amplitude and phase of (LHCP) change with rotation angle The curve showing the change in rotation angle is shown in Figure 6. A - was introduced into the phase of the transmission coefficient of the left-hand circularly polarized wave. The geometric phase shift is reduced, while the amplitude of the transmission coefficient remains almost unchanged.

[0033] According to conventional methods, when the main polarized beam of a circularly polarized array antenna scans in space, its cross-polarized beams will scan in space at an angle opposite to that of the main polarized beam. To eliminate the quasi-periodic arrangement of the antenna array phase, reduce antenna sidelobes, and minimize the accompanying scanning of the cross-circular polarization components, such as... Figure 7 As shown, the initial geometric prephase of the principal polarization (left-hand circular polarization) is set to the focal length. F = 55 mm (focal diameter ratio) F / D The spherical wave feed illumination phase (= 55 / 116 = 0.47 mm) The result is as follows Figure 7 As shown in (a). At this time, the initial phase shown in Figure 7(b) will be superimposed on the right-hand circular polarization. To achieve a pointing angle of ( , Beam scanning of ) on the array, with the index () m , n The discrete phase required by the unit. It can be calculated using the following formula:

[0034] In the formula For the gradient phase required for beam scanning, This indicates that the function value is rounded. Indicates taking the remainder. This represents the initial geometric prephase. Then the far-field electric field of the antenna... ( , It can be calculated as:

[0035]

[0036] in, The pitch angle representing beam deflection. Indicates the azimuth angle of beam deflection. This is the beamwidth factor of the antenna. The value of determines the antenna's beamwidth. This indicates the row number of antenna elements in the array antenna. This indicates the number of columns of antenna elements in the array antenna. Represents the imaginary unit. This represents the wave number of electromagnetic waves in free space. This represents the ( ) determined by the array geometry and the direction of arrival. m , n The normalized path difference of each array element relative to the array phase center. Indicates unit along x Dimensions in the axial direction Indicates unit along y Dimensions in the axial direction.

[0037] according to Figure 7 The parameters determined in the model are used to model the array antenna. The rotated element radiating patch 1 and the designed feed network are as follows: Figure 8 As shown in (a), a simulation of a 0° beam array antenna was performed, and some results are shown below. Figure 8 As shown in (b) and (c), where Figure 8 (b) Normalization at the center frequency of 10 GHz UV Planar orientation diagram Figure 8 (c) shows the normalized two-dimensional radiation pattern and axial ratio performance curve at 10 GHz. It can be seen that near the main polarization radiation direction, the cross-polarization level is low, and the cross-polarization energy is relatively uniformly distributed throughout the radiation space. Finally, the 3 dB axial ratio bandwidth of the array antenna is broadened to 9.4-10.6 GHz, with a relative bandwidth of 12.0%.

[0038] To further illustrate the advantages of the proposed reconfigurable circularly polarized array antenna compared to the conventional circularly polarized beam scanning array antenna, a simulation analysis of the conventional circularly polarized beam scanning array antenna will be performed next.

[0039] A conventional circularly polarized beam scanning array antenna refers to one whose radiating patch 1 is not rotated and is fed by an equal-amplitude, in-phase feeding network. As discussed earlier, when this antenna performs beam scanning, the cross-polarized beams will follow the main polarized beam in space. Figure 9 (a) is the structure of the radiating patch 1 of a conventional circularly polarized beam scanning array antenna, which still adopts Figure 8 The feeding network shown in (a) feeds the antenna. Similarly, a full-wave simulation of the 0° beam array antenna is performed, and some results are shown below. Figure 9 As shown in (b)-(d), where Figure 9 (b) Normalization at the center frequency of 10 GHz UV Planar orientation diagram Figure 9 (c) is the normalized two-dimensional radiation pattern at 10 GHz. Figure 9 (d) shows the shaft ratio performance curve over a wide bandwidth. (From...) Figure 9 (b) It can be seen that the main lobes of both cross-polarization and main polarization point towards the 0° direction. Figure 9The two-dimensional radiation pattern in (c) also confirms this. This results in the axial ratio bandwidth of this array antenna only covering 9.85-10.15 GHz, corresponding to a relative bandwidth of only 3.0%, such as... Figure 9 As shown in (d).

[0040] The beam scanning performance of the proposed reconfigurable circularly polarized array antenna and the conventional circularly polarized beam scanning array antenna are compared and analyzed below. For ease of description, the reconfigurable circularly polarized array antenna and the conventional circularly polarized beam scanning array antenna are referred to as Antenna 1 and Antenna 2, respectively. Figure 10 and Figure 11 The simulated Antenna 1 and Antenna 2 at 10 GHz are given respectively. xoz Face to face yoz Normalized far-field radiation patterns of the surface scanned from -45° to 45° at 15° intervals. UV The numbers 1-4 in the upper right corner of the planar radiation pattern represent the left-hand circular polarization of Antenna 1, the right-hand circular polarization of Antenna 1, the left-hand circular polarization of Antenna 2, and the right-hand circular polarization of Antenna 2, respectively. In general, the main polarization sidelobes of Antenna 1 are spatially more uniformly distributed, while the main polarization sidelobes of Antenna 2 are mainly distributed in... = sin 0cos cross-section and = 0 cross section ( 0 and (0 represents the elevation and azimuth angles of the scanning beam, respectively), and the area marked by the black elliptical dashed box in the figure has a higher sidelobe level. Antenna 2 has a higher sidelobe level than Antenna 1 in almost all scanning directions. For xoz The Antenna 2's cross-polarization main lobe scans in space along the main polarization main lobe in the -30°, 30°, -45°, and 45° planes, as well as the 30° and 45° beams in the yoz plane (marked by the red elliptical dashed boxes). This significantly degrades the Antenna 2's axial ratio performance. In contrast, the Antenna 1, due to its wavefront modulation of cross-polarization, achieves cross-polarization levels below -15 dB in all scanning directions. Furthermore, the figure shows that the half-power beamwidths of the Antenna 1 and Antenna 2 are comparable.

[0041] Figure 12The axial ratio curves for each scan beam of Antenna 1 and Antenna 2 at 10 GHz are presented. The red and green solid lines in the figure correspond to Antenna 1 and Antenna 2, respectively. It can be seen that the overall axial ratio performance of Antenna 1 is better than that of Antenna 2, especially for… xoz -45°, -30° and 45° beams and yoz With 45° and 30° beamwidths, the axial ratio performance of Antenna 2 deteriorates significantly, while the axial ratio of Antenna 1 remains almost entirely below 3 dB.

[0042] Figure 13 The scanning beams of Antenna 1 and Antenna 2 are given. S The parameter simulation results show that the matching performance of the two antennas is similar.

[0043] In summary, the radiating patch 1 of the present invention radiates circularly polarized waves by rotating the radiating patch 1 by an angle. α This can introduce - for left-handed and right-handed circular polarization of radiation respectively. α and α The geometric phase. Furthermore, for circularly polarized antennas, under reasonable structural and dimensional conditions, by rotating the radiating structure of the element, geometric phase shifts of the same magnitude but opposite signs can be introduced into the radiated left-hand and right-hand circularly polarized components. For antenna elements fed using a back-feed structure (the bottom layer is a microstrip line, phase shifter, etc., and the top layer is a radiating structure, connected to the bottom layer by metallized vias), the transmission phase of the element can be controlled by changing the length of the feed microstrip line or adjusting the state of the phase shifter. This phase is simultaneously superimposed on each polarization component of the radiated electromagnetic wave, ultimately resulting in the left-hand and right-hand circularly polarized phases. (LHCP) and (RHCP) can be represented as (LHCP) = + α (RHCP) = – α In the formula, α represents the geometric phase of left-handed circular polarization. The transmission phase is introduced to change the length of the feed microstrip line or adjust the state of the phase shifter. Therefore, the initial phase configuration of the main polarization wave and the cross-polarization wave can be achieved by comprehensively utilizing the geometric phase and the transmission phase. This antenna, which superimposes the initial geometric pre-phase, rationally sets the phase distribution of the main polarization and cross-polarization using the geometric phase and the transmission phase, reduces the cross-polarization level in the main polarization radiation direction, and makes it more uniformly distributed in the radiation space outside the main polarization beam direction, which can effectively improve the axial ratio performance of the circularly polarized antenna. In addition, this phase configuration breaks the quasi-symmetry of the phase distribution on the array surface, which can effectively reduce sidelobes. Traditional circularly polarized phased array antennas can only be controlled by the transmission phase or the geometric phase, with low degrees of freedom of control and usually narrow circular polarization axial ratio bandwidth. During large-angle scanning, the sidelobe level rises. Therefore, compared with conventional circularly polarized beam scanning array antennas, the proposed reconfigurable circularly polarized array antenna has significant advantages. Specifically, the proposed reconfigurable circularly polarized array antenna has lower sidelobe level and better axial ratio performance.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pattern-reconfigurable circularly polarized array antenna, characterized in that, The device comprises multiple antenna elements arranged in a matrix pattern. Each antenna element includes, from top to bottom, a radiating patch, a first metal ground plane, a first DC bias circuit, a second DC bias circuit, a second metal ground plane, and a 90-degree phase shifter. The radiating patch and the first metal ground plane are etched onto the upper and lower surfaces of a first dielectric substrate, respectively. The first and second DC bias circuits are etched onto the upper and lower surfaces of a second dielectric substrate, respectively. The second metal ground plane and the 90-degree phase shifter are etched onto the upper and lower surfaces of a third dielectric substrate, respectively. The three dielectric substrates are bonded together using two prepregs. The radiating patch of each antenna element integrates the first... The first diode and the second diode are connected, with the cathode of the first diode and the anode of the second diode connected to the second DC bias circuit and the 90-degree phase shifter through the first metallized via. The anode of the first diode and the cathode of the second diode are connected to the first metal ground plane through a microstrip line and the second metallized via. The 90-degree phase shifter of each unit integrates a third diode and a fourth diode. The cathodes of the third diode and the fourth diode are connected to the second metal ground plane through a microstrip line and the fourth metallized via. The anodes of the third diode and the fourth diode are connected to the first DC bias circuit through another microstrip line and the third metallized via.

2. The pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, The 90-degree phase shifter has a structure in which a grid-like metal region is etched on the lower surface of the third dielectric substrate. This metal region includes a main line and a secondary line. The main line is the connection line between the negative terminals of the third diode and the fourth diode. The two ends of the main line are respectively provided with a first port and a second port, serving as a feed port and a receive port. The secondary line is a line parallel to the main line, with both ends set in a stepped shape. The negative terminal of the third diode is perpendicularly connected to the main line through a branch line, and the negative terminal of the fourth diode is perpendicularly connected to the main line through another branch line. The positive terminal of the third diode is connected to the secondary line, and the positive terminal of the fourth diode is connected to the secondary line. A microstrip line is connected to both the main line and the secondary line.

3. A pattern-reconfigurable circularly polarized array antenna according to claim 2, characterized in that, The main line consists of three parts: a middle section, a first section and a second section connected to the middle section. A 100 pF lumped capacitor is connected between the first section and the middle section, and between the second section and the middle section. The first section and the second section have the same width but are narrower than the middle section. The ends of the first section and the second section are respectively provided with a first port and a second port, which serve as a power supply port and a receiving port.

4. A pattern-reconfigurable circularly polarized array antenna according to claim 3, characterized in that, The optimization method for the 90-degree phase shifter is as follows: The center operating frequency of the 90-degree phase shifter was set to 10 GHz. With the optimization goal of minimizing insertion loss and maximizing phase shifting performance, the linewidths of the first and second segments of the main line were adjusted. w 1. Line width in the middle section w 3. Branch line width w 2 and length l 2. Line width in the middle area of ​​the sub-line w 4. Width of the stepped structure at both ends of the sub-line w 5 and length l 1. The final determined structural parameters of the phase shifter are as follows: l 1 = 2.6 l 2 = 3.1, l 3 = 3.5 w 1 = 1.08 w 2 = 0.6, w 3 = 1.5 w 4 = 0.8 w 5 = 3.25, unit mm.

5. A pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, The structure of the radiating patch of the antenna unit is as follows: a rectangular metal region is etched on the upper surface of the first dielectric substrate. One side of the rectangular metal region is connected to a microstrip line. The two diagonals of the rectangular metal region are cut off. An H-shaped insulating region is etched in the middle of the rectangular metal region. A rectangular metal sheet is located at the center of the H-shaped insulating region. The positive and negative terminals of the first diode are connected by a gap between the rectangular metal sheet and the upper part of the H-shaped insulating region. The positive and negative terminals of the second diode are connected by a gap between the rectangular metal sheet and the lower part of the H-shaped insulating region.

6. A pattern-reconfigurable circularly polarized array antenna according to claim 5, characterized in that, The optimization method for the antenna element is as follows: The center operating frequency of the antenna element was set to 10 GHz, the operating polarization was determined to be left-hand circular polarization, and the thickness of the first dielectric substrate was adjusted to optimize the antenna element by minimizing insertion loss and maximizing phase shift performance. h 1. Thickness of the second dielectric substrate h 2. Thickness of the third dielectric substrate h 3. Width of the entire array antenna p The width of the rectangular metal area of ​​the radiating patch pp The length of the hypotenuse after cutting off the diagonal of the rectangular metal region of the radiating patch. s The height of the H-shaped insulation zone ps The outer diameter of the first metallized via d v1 Outer diameter of the first metal ground plane anti-solder pad d k1 The outer diameter of the third metallized via connecting the phase shifter and the first DC bias circuit. d v2 And the outer diameter of the anti-pad associated with the first DC bias circuit on the second metal floor. d k2 Through simulation and optimization, the structural parameters of the antenna element were finally determined as follows: h 1 = 2, h 2 = 0.25 h 3 = 0.5 s = 2.74, ps =3.9, pp = 6.64, d v1 = 0.6, d k1 = 2.4, d v2 = 0.4, d k2 = 2, p = 14.5, unit mm.

7. A pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, The radiating patch configuration of the array antenna has an initial geometric pre-phase, setting the initial phase of the left-hand circular polarization of the antenna element to the illumination phase of the spherical wave feed with a focal length F = 55 mm. Radiation patches based on phase Determine their respective rotation angles, where the discrete phase required to be provided by the radiating patch in the m-th row and n-th column of the array antenna. Calculated by the following formula: In the formula, For the gradient phase required for beam scanning, This indicates that the function value is rounded. Indicates taking the remainder. Indicating the initial geometric prephase, the far-field electric field of the antenna... ( , The calculation is as follows: in, The pitch angle representing beam deflection. Indicates the azimuth angle of beam deflection. This is the beamwidth factor of the antenna. This indicates the row number of antenna elements in the array antenna. This indicates the number of columns of antenna elements in the array antenna. Represents the imaginary unit. This represents the wave number of electromagnetic waves in free space. This represents the ( ) determined by the array geometry and the direction of arrival. m , n The normalized path difference of each array element relative to the array phase center. Indicates unit along x Dimensions in the axial direction Indicates unit along y Dimensions in the axial direction.

8. A pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, When each antenna element is in operation, both the first and second metal ground planes are connected to DC ground. The cutoff and conduction of the first and second diodes are controlled by signals on the first DC bias circuit, and the cutoff and conduction of the third and fourth diodes are controlled by signals on the second DC bias circuit.

9. A pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, The first dielectric substrate is an F4B substrate with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 2 mm; the second dielectric substrate is an F4B substrate with a relative permittivity of 2.2, a loss tangent of 0.001, and a thickness of 0.25 mm; and the third dielectric substrate is an F4B substrate with a relative permittivity of 3.5, a loss tangent of 0.001, and a thickness of 0.5 mm.

10. A pattern-reconfigurable circularly polarized array antenna according to claim 1, characterized in that, All four diodes are PIN diodes, and their model number is MADP-000907-14020.

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