Dual-circularly polarized reflectarray antenna and radiation beam independent control method therefor

Abstract

Disclosed in the present invention are a dual-circularly polarized reflectarray antenna and a radiation beam independent control method therefor. The antenna comprises a circularly polarized antenna feed source and a double "S"-printed metal strip reflectarray; the circularly polarized antenna feed source faces the double "S"-printed metal strip reflectarray; the circularly polarized antenna feed source is located at a phase shift focus of the double "S"-printed metal strip reflectarray; the circularly polarized antenna feed source emits spherical electromagnetic waves, and the double "S"-printed metal strip reflectarray receives the spherical electromagnetic waves and reflects same as plane waves. The dual-circularly polarized reflectarray antenna provided by the present invention can simultaneously reflect left-handed circularly polarized waves and right-handed circularly polarized waves, and implements, while ensuring high-gain radiation, the characteristic that left-handed circularly polarized wave beams and right-handed circularly polarized wave radiation beams are independently controllable.

Description

Dual circularly polarized reflectarray antenna and independent radiation beam control method thereof Technical Field

[0001] The present invention belongs to the field of radar communication technology, and in particular relates to a dual circularly polarized reflectarray antenna and a method for independently controlling radiation beams thereof. Background Art

[0002] With the rapid development of modern satellite communication technology, high-throughput satellites with multi-beam payloads have been widely developed. One of the key challenges in designing, developing, and launching such satellites is the large number of antennas required to handle the mission. These satellites typically use a four-color frequency / polarization multiplexing scheme. Therefore, designing dual circularly polarized reflectarray antennas operating at the same frequency can effectively reduce the number of antennas required by the satellite.

[0003] Antennas are crucial components of modern weaponry and radar detection systems, often requiring high gain. Reflectarray antennas, consisting of a horn feed and a reflectarray, offer the advantages of high gain and the absence of complex feed networks, making them of great research value. Their operating mechanism is as follows: a reflectarray with a phase-shifting function converts spherical waves from the feed into plane waves, which are then radiated outward, achieving high-gain radiation performance.

[0004] Existing dual-circular polarization reflectarray antennas are often implemented by combining a linear-circular polarization converter and a linear polarization reflectarray antenna, such as M.-A. Joyal, R. El Hani, M. Riel, Y. Demers and J.-J. Laurin, "A Reflectarray-Based Dual-Surface Reflector Working in Circular Polarization," in IEEE Transactions on Antennas and Propagation, vol. 63, no. 4, pp. 1306-1313, April 2013. In 2015, the input circularly polarized wave was converted into horizontal linear polarized wave and vertical linear polarized wave. The horizontal linear polarized wave and vertical linear polarized wave were reflected respectively by a reflective array that reflects horizontal linear polarized wave and transmits vertical linear polarized wave, and a parabolic reflector. The two reflected linear polarized waves were then converted into circularly polarized wave output by a linear-circular polarization converter. However, in order to achieve the output of left-handed circularly polarized wave and right-handed circularly polarized wave at different angles, the various components needed to be built at different angles, which made the processing very difficult. A Chinese patent application titled "A dual-frequency dual-circularly polarized folded reflectarray antenna" (application number: CN 202111341584.5, publication number: CN 114069256A) proposes a dual-frequency dual-circularly polarized folded reflectarray antenna, comprising a primary reflector, a secondary transmission mirror, a support structure, and a feed source. The primary reflector comprises a first dielectric substrate with a hollow center, the upper surface of which is printed with periodically arranged square ring metal patches, and the lower surface is printed with a metal floor; the secondary transmission mirror comprises a second dielectric substrate and a third dielectric substrate stacked up and down, the lower surface of the second dielectric substrate is printed with a metal floor with a leaky wave slot, and the upper surface of the second dielectric substrate and the lower surface of the third dielectric substrate are both printed with two circular metal patches of different specifications, which are connected by metallized vias passing through the leaky wave slots. The disadvantage of this method is that it requires a multi-layer structure, a complex structure, and cannot simultaneously reflect left-handed circularly polarized waves and right-handed circularly polarized waves at the same frequency.

[0005] Furthermore, S. Mener, R. Gillard, R. Sauleau, A. Bellion, and P. Potier, "Dual Circularly Polarized Reflectarray With Independent Control of Polarizations," in IEEE Transactions on Antennas and Propagation., employ a circularly polarized selective surface and a half-wave plate reflector unit. The circular polarization selection of the first functional layer allows for separation and independent control of the two circular polarizations. However, this method's units are difficult to miniaturize and exhibit poor oblique-incidence performance. Furthermore, the method also consists of a multi-layer planar structure with a high unit profile and complex structure, placing high demands on fabrication. Therefore, a dual circularly polarized reflectarray antenna with independently controllable radiation beams is needed.

[0006] Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a dual circularly polarized reflectarray antenna with independently controllable radiation beams. The dual circularly polarized reflectarray antenna is formed by forming a reflection unit with two dielectric substrates and two groups of "S"-shaped printed metal strips, and then forming a reflectarray. The dual circularly polarized reflectarray antenna has a simple structure and can simultaneously reflect left-handed circularly polarized waves and right-handed circularly polarized waves while ensuring good radiation performance of the antenna. The radiation beams can be independently controlled.

[0008] The present invention adopts the following technical solutions to solve the above technical problems:

[0009] A dual circularly polarized reflectarray antenna includes a circularly polarized antenna feed for transmitting spherical electromagnetic waves and a dual "S"-shaped printed metal strip reflectarray for receiving the spherical electromagnetic waves and reflecting them into plane waves; the dual "S"-shaped printed metal strip reflectarray is composed of an array of multiple dual "S"-shaped printed metal strip reflective units.

[0010] The circularly polarized antenna feed is directed toward the double “S” shaped printed metal strip reflective array along the -z direction and is located at the phase shift focus of the double “S” shaped printed metal strip reflective array.

[0011] Furthermore, the double "S"-shaped printed metal strip reflective unit includes two vertically orthogonal dielectric substrates, each of which is provided with two symmetrical semi-S-shaped printed metal strips; the two dielectric substrates are assembled by plugging to form two groups of cascaded "S"-shaped printed metal strips.

[0012] Furthermore, in the double "S"-shaped printed metal strip reflection unit, the first group of "S"-shaped printed metal strips and the second group of "S"-shaped printed metal strips have the same size, which is the working center frequency wavelength.

[0013] The first group of "S"-shaped printed metal strips reflects left-handed circularly polarized waves and is located near one end of the circularly polarized antenna feed source, and the second group of "S"-shaped printed metal strips reflects right-handed circularly polarized waves and is located far away from the circularly polarized antenna feed source.

[0014] Furthermore, the two sets of "S"-shaped printed metal strips in each double "S"-shaped printed metal strip reflector are located at different positions on the dielectric substrate to meet the different compensation phases required for left-handed circularly polarized waves and right-handed circularly polarized waves. The specific position calculation content is:

[0015] Step 1: Calculate the reflection phase. The specific formula is:

[0016] in, is the reflection phase of the i-th double “S” type printed metal strip reflection unit, i ranges from 1 to M×N; k is the propagation constant in free space; R i is the distance from the circularly polarized antenna feed source 1 to the i-th double “S”-shaped printed metal strip reflector unit; is the position vector of the i-th double “S”-shaped printed metal strip reflector unit; is the direction in which the antenna radiates the main beam; is a phase constant that represents the required phase shift value for the double “S” type printed metal strip reflective array.

[0017] Step 2: The relationship between the position of the “S”-shaped printed metal strip on the dielectric substrate and the reflection phase is:

[0018] Wherein, dz and dz1 represent the relative positions of two groups of “S”-shaped printed metal strips on the dielectric substrate.

[0019] Furthermore, the double "S"-shaped printed metal strip reflective units are arranged in an array, and the specific arrangement method includes: arranging a number of double "S"-shaped printed metal strip reflective units in parallel in sequence along the x direction, and stacking a number of double "S"-shaped printed metal strip reflective units in sequence along the y direction.

[0020] Furthermore, the distance between the “S”-shaped printed metal strips and the adjacent double “S”-shaped printed metal strip reflective units arranged in parallel in the x-direction is recorded as the first distance.

[0021] The distance between the "S"-shaped printed metal strips and the adjacent double "S"-shaped printed metal strip reflective units stacked in the y direction is recorded as the second distance.

[0022] The first distance is equal to the second distance.

[0023] Furthermore, the present invention also proposes a method for independently controlling the radiation beam of a dual circularly polarized reflectarray antenna. For the first group of "S"-shaped printed metal strips, when the incident electromagnetic wave is a left-handed circularly polarized wave, the electric field vector Counterclockwise rotation; when the direction of the electric field vector is in the +x direction, a current i1 is generated on the "S"-shaped printed metal strip; when the direction of the electric field vector is in the +y direction, a current i2 is generated on the "S"-shaped printed metal strip in the opposite direction to the current i1; i2 has a 90° phase delay compared to i1. Since the total electrical length of the printed metal strip at the connection between the dielectric substrate in the x direction and the dielectric substrate in the y direction is λ / 4, i1 has a 90° phase delay compared to i2. Therefore, the phase delays of the two cancel each other out, and equal-amplitude and opposite-direction currents are excited on the "S"-shaped printed metal strip, which exhibits a wavelength resonance as a whole, and the left-handed circularly polarized wave is reflected; where λ is the wavelength of the operating center frequency.

[0024] When the incident electromagnetic wave is a right-hand circularly polarized wave, the electric field vector Clockwise rotation; when the direction of the electric field vector is in the +y direction, a current i1 is generated on the "S"-shaped printed metal strip; when the direction of the electric field vector is in the +x direction, a current i2 is generated on the "S"-shaped printed metal strip in the opposite direction to the current i1, and i2 has a 90° phase delay compared to i1. Since the total electrical length of the printed metal strip at the connection between the dielectric substrate in the x direction and the dielectric substrate in the y direction is λ / 4, i2 has a 90° phase delay compared to i1, so i2 has a total phase delay of 180° compared to i1. i2 and i1 have the same direction, and the currents of the two cancel each other out, and the entire structure exhibits a non-resonant transmission state.

[0025] Furthermore, for the second group of "S"-shaped printed metal strips, when the incident electromagnetic wave is a left-hand circularly polarized wave or a right-hand circularly polarized wave, the current situation generated on the first group of "S"-shaped printed metal strips is opposite to that; among them, when the incident electromagnetic wave is a left-hand circularly polarized wave, the currents on the second group of "S"-shaped printed metal strips are canceled out, and the entire structure exhibits a non-resonant transmission state; when the incident electromagnetic wave is a right-hand circularly polarized wave, equal-amplitude and opposite currents will be excited on the second group of "S"-shaped printed metal strips, and the whole exhibits a wavelength resonance, and the right-hand circularly polarized wave is reflected.

[0026] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0027] The dual circularly polarized reflectarray antenna proposed in this invention, based on dual "S"-shaped printed metal strips, can simultaneously reflect left-handed and right-handed circularly polarized waves, achieving independent and controllable radiation beams for both left-handed and right-handed circularly polarized waves while ensuring high-gain radiation. Furthermore, the reflective unit of the dual "S"-shaped printed metal strips proposed in this invention has a simple structure and excellent performance, making it easy to manufacture and implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic diagram of the three-dimensional structure of the dual circularly polarized reflectarray antenna of the present invention.

[0029] FIG2 is a schematic diagram of the three-dimensional structure of the double “S”-shaped printed metal strip reflective unit of the present invention.

[0030] FIG3 is a schematic diagram of the planar structure of the dielectric substrate and the “S”-shaped printed metal strip of the double “S”-shaped printed metal strip reflective unit of the present invention.

[0031] FIG4 is a graph showing a variation trend of the aperture efficiency of the reflectarray antenna with F / D in an embodiment of the present invention.

[0032] FIG5 is a graph showing the gain and axial ratio of the reflectarray antenna at the radiation center frequency of 10 GHz as a function of F / D for left-hand circularly polarized waves and right-hand circularly polarized waves according to an embodiment of the present invention.

[0033] Figure 6 shows the reflection phase required in an embodiment of the present invention, where (a) of Figure 6 shows the reflection phase required by each double "S"-shaped printed metal strip reflection unit of the reflectarray antenna when a left-handed circularly polarized wave is incident, and (b) of Figure 6 shows the reflection phase required by each double "S"-shaped printed metal strip reflection unit of the reflectarray antenna when a right-handed circularly polarized wave is incident.

[0034] 7 is a diagram showing the relationship between the relative position of the first group of “S”-shaped printed metal strips on the dielectric substrate and their reflection phase and reflection amplitude at the antenna radiation center frequency of 10 GHz in the double “S”-shaped printed metal strip reflection unit in an embodiment of the present invention.

[0035] 8 is a diagram showing the relationship between the relative position of the second group of “S”-shaped printed metal strips on the dielectric substrate and their reflection phase and reflection amplitude at the antenna radiation center frequency of 10 GHz in the double “S”-shaped printed metal strip reflection unit in an embodiment of the present invention.

[0036] FIG9 is a graph showing how the gain and axial ratio of the reflectarray antenna vary with frequency for left-hand circularly polarized waves and right-hand circularly polarized waves in the frequency band from 9 GHz to 11 GHz according to an embodiment of the present invention.

[0037] FIG10 is a far-field pattern of left-handed circularly polarized waves and right-handed circularly polarized waves of the reflectarray antenna at a radiation center frequency of 10 GHz in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below based on the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0039] The present invention will be further described in detail below with reference to the accompanying drawings.

[0040] The present invention proposes a dual circularly polarized reflectarray antenna with independently controllable radiation beams. The three-dimensional structure is shown in Figure 1 and includes a circularly polarized antenna feed 1 and a dual "S"-shaped printed metal strip reflectarray 2. The circularly polarized antenna feed 1 is oriented along the -z direction toward the dual "S"-shaped printed metal strip reflectarray 2 and is located directly in front of the dual "S"-shaped printed metal strip reflectarray 2, at the phase shift focus of the dual "S"-shaped printed metal strip reflectarray 2. This allows the spherical electromagnetic waves radiated by the circularly polarized antenna feed 1 to be transformed into uniform plane waves after reflection. The distance between the phase center of the circularly polarized antenna feed 1 and the reflective array surface of the dual "S"-shaped printed metal strip reflectarray 2 is 217 mm.

[0041] The double “S” shaped printed metal strip reflective array 2 is composed of 31×31 double “S” shaped printed metal strip reflective units 3 with the same structure and different relative positions of the two groups of “S” shaped printed metal strips on the dielectric substrate. The double “S” shaped printed metal strip reflective units 3 are periodically extended along the y-axis and then periodically stacked at a certain interval along the x-axis, where p x is the period of the double “S” shaped printed metal strip reflective units 3 arranged in parallel along the x direction, p y is the periodic size of the stacked double "S"-shaped printed metal strip reflector units 3 along the y-direction. The three-dimensional structure of the double "S"-shaped printed metal strip reflector unit 3 is shown in Figure 2, and comprises two perpendicularly intersecting dielectric substrates and two "symmetrical" printed metal strips disposed on the dielectric substrates. The RO4003C dielectric substrate was selected, with a thickness of 0.406 mm, a relative dielectric constant of 3.55, and a loss tangent of 0.0027. The printed metal strips were made of copper with a thickness of 0.017 mm. The two dielectric substrates of the double "S"-shaped printed metal strip reflector unit 3 are assembled by plugging together, forming two sets of cascaded "S"-shaped printed metal strips. The two parts of the "S"-shaped printed metal strips are connected by welding.

[0042] The unit period size of the double "S"-shaped printed metal strip reflective unit 3 is related to oblique incidence performance: smaller unit periods improve oblique incidence performance. This example simulates different unit period sizes. When the unit period is larger than 7mm, the oblique incidence reflection performance deteriorates significantly. When the unit period is smaller than 7mm, since the unit period is already relatively small, further reduction does not significantly improve the reflection performance. However, for the same aperture size, the number of units will increase. Therefore, 7mm was selected as the unit period size for this example.

[0043] The planar structure of the double “S” shaped printed metal strip reflector unit 3 is shown in FIG3 . The first group of “S” shaped printed metal strips 4 and the second group of “S” shaped printed metal strips 5 in each double “S” shaped printed metal strip reflector unit 3 have the same size, both being l 1+ l 2+ l 3+ The total length of l4 is 1 wavelength of the working center frequency. z is the length of the double “S” shaped printed metal strip reflecting unit 3 in the z direction, l1, l2, l3, l4 are the lengths of the “S” shaped printed metal strips, r is the curvature of the “S” shaped printed metal strips, w is the width of the “S” shaped printed metal strips, dz and dz1 are the relative positions of the two groups of “S” shaped printed metal strips on the dielectric substrate.

[0044] The physical parameters in this example are: x =7mm, p y =7mm, p z =50mm, l1=2.625mm, l2=3.41mm, l3=4.5mm, l4=1.9mm, r=1mm, w=0.15mm.

[0045] The first group of "S"-shaped printed metal strips 4 reflects left-handed circularly polarized waves and is located near one end of the circularly polarized antenna feed 1, that is, at coordinate dz. The second group of "S"-shaped printed metal strips 5 reflects right-handed circularly polarized waves and is located far from the circularly polarized antenna feed 1, that is, at coordinate dz1. The double "S"-shaped printed metal strip reflective array 2 adjusts the reflection phases of left-handed circularly polarized waves and right-handed circularly polarized waves by respectively changing the positions of the first group of "S"-shaped printed metal strips 4 and the second group of "S"-shaped printed metal strips 5 on the dielectric substrate. In order to ensure that the energy secondary radiated / scattered by the double "S"-shaped printed metal strip reflective array 2 after being irradiated by the circularly polarized antenna feed 1 has high gain characteristics, the positions of the two groups of "S"-shaped printed metal strips on the dielectric substrate in each double "S"-shaped printed metal strip reflective unit 3 are different.

[0046] The working principle is:

[0047] Step 1: Determine the size D and appropriate focal diameter ratio F / D of the double "S" shaped printed metal strip reflect array 2, where F is the distance between the circularly polarized antenna feed 1 and the double "S" shaped printed metal strip reflect array 2. The determination of the F / D value depends on the aperture efficiency, and the main factors affecting the aperture efficiency are the taper efficiency and the overflow efficiency. The specific calculation formula is:

[0048] Among them, η taper is the taper efficiency; η spillover is the overflow efficiency; A is the aperture area; P is the Poynting vector of the electromagnetic wave radiated by the circularly polarized antenna feed source, which can be approximately calculated by the cosine function model; I represents the excitation received by each array element.

[0049] Based on the above formula, we can derive a trend chart of the reflectarray antenna's aperture efficiency as a function of F / D. As shown in Figure 4, as the focal ratio increases, the circularly polarized antenna feed gradually moves away from the reflector array, causing more radiated energy to overflow the array and making the energy irradiated more evenly across the array. The overflow efficiency decreases with increasing focal ratio, while the tapering efficiency increases. Theoretically, the optimal aperture efficiency corresponds to an F / D of approximately 0.9. However, the performance of the reflectarray antenna under different F / D conditions is verified using the simulation diagram shown in Figure 5. The horizontal axis of the figure represents frequency in GHz, while the vertical axis represents gain and axial ratio in dB. The relationship between the gain and axial ratio of left-hand circularly polarized waves and right-hand circularly polarized waves at the radiation center frequency of 10 GHz is shown respectively. It can be found that the performance is optimal when F / D = 1. This is because when F / D = 0.9, the incident angle of the circularly polarized antenna feed to the edge of the array becomes larger, and the large-angle oblique incidence will affect the response of the double "S"-shaped printed metal strip reflector unit 3, which is ultimately reflected in the performance of the reflectarray antenna as a decrease in gain and a worsening of the axial ratio.

[0050] Therefore, in this embodiment, the value of F / D is selected as 1.

[0051] Step 2: Based on the F / D value in step 1 and the reflection angles of -15° and +15° required for left-handed and right-handed circularly polarized waves, respectively, determine the reflection phase required by the double "S"-shaped printed metal strip reflection unit 3 when the left-handed circularly polarized wave and the right-handed circularly polarized wave are incident. The specific content is:

[0052] (1) Calculate the reflection phase. The specific formula is:

[0053] in, is the reflection phase of the i-th double “S” type printed metal strip reflection unit 3, where i ranges from 1 to 961 (i.e., 31×31); k is the propagation constant in free space; R iis the distance from the circularly polarized antenna feed source 1 to the i-th double “S”-shaped printed metal strip reflector unit 3; is the position vector of the i-th double “S”-shaped printed metal strip reflective unit 3; is the direction in which the antenna radiates the main beam; is a phase constant, indicating that the phase shift value required by the double “S” type printed metal strip reflective array 2 is a relative phase value rather than an absolute phase value.

[0054] (2) The relationship between the position of the “S”-shaped printed metal strip on the dielectric substrate and the reflection phase is:

[0055] Wherein, dz and dz1 represent the relative positions of two groups of “S”-shaped printed metal strips on the dielectric substrate.

[0056] Since the length p of the dielectric substrate in the z direction z The reflection phase of left-hand circularly polarized wave and right-hand circularly polarized wave that can be achieved by each unit is determined based on the above formula. The range will be exceeded The value is folded and the 360° phase value is subtracted. As shown in Figure 6, the horizontal and vertical axes in the figure represent the number of units in the x-direction and y-direction, with a total of 31×31 grids. The depth of each grid color represents the different reflection phase values ​​required by the double "S" type printed metal strip reflector unit 3 at that position. Figure 6 (a) represents the reflection phase required by each double "S" type printed metal strip reflector unit 3 when a left-handed circularly polarized wave is incident, and Figure 6 (b) represents the reflection phase required by each double "S" type printed metal strip reflector unit 3 when a right-handed circularly polarized wave is incident.

[0057] Step 3. According to the reflection phase required by the double "S"-shaped printed metal strip reflection unit 3 and the relationship between the position of the two groups of "S"-shaped printed metal strips on the dielectric substrate and the reflection phase of the left-handed circularly polarized wave and the right-handed circularly polarized wave, the position of the two groups of "S"-shaped printed metal strips in each unit on the dielectric substrate is determined, thereby determining the final structure of the entire double "S"-shaped printed metal strip reflection array 2.

[0058] Step 4: Place the circularly polarized antenna feed 1 and the dual "S"-shaped printed metal strip reflectarray 2 according to the positional relationship shown in Figure 1. The distance between the circularly polarized antenna feed 1 and the dual "S"-shaped printed metal strip reflectarray 2 is determined by F determined in Step 1. At this point, the entire dual circularly polarized reflectarray antenna is constructed.

[0059] Step 5: Taking one of the double “S” shaped printed metal strip reflective units 3 as an example, for the first group of “S” shaped printed metal strips 4, when the incident electromagnetic wave is a left-handed circularly polarized wave, the electric field vector Rotating counterclockwise. When the electric field vector is oriented in the +x direction, a current i1 is generated in the S-shaped printed metal strip. When the electric field vector is oriented in the +y direction, a current i2 is generated in the S-shaped printed metal strip in the opposite direction to current i1. Although i2 has a 90° phase delay compared to i1, the total electrical length of the printed metal strip connecting the dielectric substrate in the x-direction and the dielectric substrate in the y-direction is λ / 4, resulting in a 90° phase delay between i1 and i2. Therefore, the two phase delays cancel each other out. Equal-amplitude and opposite-direction currents are excited in the S-shaped printed metal strip, resulting in a single wavelength resonance, and a left-handed circularly polarized wave is reflected.

[0060] When the incident electromagnetic wave is a right-hand circularly polarized wave, the electric field vector Clockwise rotation. When the electric field vector is in the +y direction, a current i1 is generated on the "S"-shaped printed metal strip. When the electric field vector is in the +x direction, a current i2 is generated on the "S"-shaped printed metal strip in the opposite direction to the current i1. i2 has a 90° phase delay compared to i1. Since the total electrical length of the printed metal strip connecting the dielectric substrate in the x-direction and the dielectric substrate in the y-direction is λ / 4, i2 has a 90° phase delay compared to i1. Therefore, i2 has a total phase delay of 180° compared to i1. Since i2 and i1 have the same direction, the currents cancel each other out, and the entire structure exhibits a non-resonant transmission state.

[0061] Similarly, for the second group of “S”-shaped printed metal strips 5, when the incident electromagnetic wave is a left-handed circularly polarized wave, the electric field vector Rotates counterclockwise. When the electric field vector is in the +x direction, a current i1 is generated on the "S"-shaped printed metal strip. When the electric field vector is in the +y direction, a current i2 is generated on the "S"-shaped printed metal strip in the opposite direction of current i1, with a 90° phase delay compared to i1. At the same time, since the total electrical length of the printed metal strip connecting the dielectric substrate in the x-direction and the dielectric substrate in the y-direction is λ / 4, i2 will also have a 90° phase delay compared to i1. Therefore, i2 will have a total phase delay of 180° compared to i1. Since i1 and i2 have the same direction, the currents cancel each other out, and the entire structure exhibits a non-resonant transmission state.

[0062] When the incident electromagnetic wave is a right-hand circularly polarized wave, the electric field vector Clockwise rotation. When the electric field vector is in the +y direction, a current i1 is generated on the "S"-shaped printed metal strip. When the electric field vector is in the +x direction, a current i2 is generated on the "S"-shaped printed metal strip in the opposite direction to current i1. i2 has a 90° phase delay compared to i1. Since the total electrical length of the printed metal strip connecting the dielectric substrate in the x-direction and the dielectric substrate in the y-direction is λ / 4, i1 also has a 90° phase delay compared to i2. Therefore, the relative phase delays of the two cancel each other out, exciting equal-amplitude and opposite-direction currents on the "S"-shaped printed metal strip, which exhibits a wavelength resonance as a whole, and a right-handed circularly polarized wave is reflected.

[0063] Figure 7 shows the relationship between the position of the first group of "S"-shaped printed metal strips 4 in the double "S"-shaped printed metal strip reflector unit 3 on the dielectric substrate and the reflection phase of the left-handed circularly polarized wave and the right-handed circularly polarized wave at the antenna radiation center frequency of 10 GHz. The horizontal axis in the figure is the position of the double "S"-shaped printed metal strips on the dielectric substrate, with the unit being millimeters (mm), and the vertical axis in the figure is the phase and reflection amplitude, with the units being degrees (deg) and dB, respectively. As can be seen from the figure, changing dz will change the reflection phase of the left-handed circularly polarized wave, but has little effect on the reflection phase of the right-handed circularly polarized wave, and the reflection amplitude of the left-handed circularly polarized wave and the right-handed circularly polarized wave. Therefore, by changing dz, the requirements for the reflection phase of the left-handed circularly polarized wave for each double "S"-shaped printed metal strip reflector unit 3 can be met.

[0064] Figure 8 shows the relationship between the position of the second set of "S"-shaped printed metal strips 5 in the dual "S"-shaped printed metal strip reflector unit 3 on the dielectric substrate and the reflection phase of left-handed and right-handed circularly polarized waves at the antenna radiation center frequency of 10 GHz. As can be seen from the figure, changing dz1 changes the reflection phase of right-handed circularly polarized waves, but has little effect on the reflection phase of left-handed circularly polarized waves or the reflection amplitudes of left-handed and right-handed circularly polarized waves. Therefore, by changing dz1, the required reflection phase of right-handed circularly polarized waves for each dual "S"-shaped printed metal strip reflector unit 3 can be met.

[0065] The two groups of "S"-shaped printed metal strips in the double "S"-shaped printed metal strip reflection unit 3 move forward and backward without interfering with each other. The reflection phase of the double "S"-shaped printed metal strip reflection unit 3 can be uniquely determined by the positions of the two groups of "S"-shaped printed metal strips on the dielectric substrate.

[0066] Figure 9 shows the frequency-dependent gain and axial ratio curves of the reflectarray antenna for left-hand circularly polarized waves and right-hand circularly polarized waves. The horizontal axis represents frequency in GHz, while the vertical axis represents gain and axial ratio in dB. At the antenna's radiation center frequency of 10 GHz, the reflectarray antenna achieves high gain characteristics of 24.2 dB for left-hand circularly polarized waves and 23.5 dB for right-hand circularly polarized waves. The 1 dB gain reduction ranges are 9.49 GHz to 10.15 GHz and 9.53 GHz to 10.17 GHz, respectively. The absolute bandwidths are 0.66 GHz and 0.64 GHz, respectively, and the relative bandwidths are approximately 6.7% and 6.5%, respectively. The 3 dB axial ratio ranges are 8.02 to 10.57 GHz and 9.06 to 10.86 GHz, respectively, with absolute bandwidths of 2.55 GHz and 1.8 GHz, respectively, and relative bandwidths of approximately 27.6% and 18.1%, respectively.

[0067] Figure 10 shows the normalized far-field patterns of the reflectarray antenna for left-hand circularly polarized waves and right-hand circularly polarized waves at the radiation center frequency. The horizontal axis represents the angle in degrees, and the vertical axis represents the gain in dB. As can be seen from the figure, this high-gain reflectarray antenna achieves a narrow beam and relatively low sidelobe levels at all angles. The maximum sidelobe level for left-hand circularly polarized waves is only approximately -16 dB, and for right-hand circularly polarized waves, the maximum sidelobe level is only approximately -13.6 dB. Furthermore, this high-gain reflectarray antenna exhibits excellent cross-polarization isolation, with cross-polarization levels below -20 dB for both left-hand and right-hand circularly polarized waves.

[0068] The experimental results above demonstrate that the proposed antenna achieves excellent high-gain radiation, reflecting both left-handed and right-handed circularly polarized waves simultaneously. While maintaining high-gain radiation, it also achieves independent controllability of both left-handed and right-handed circularly polarized beams. Furthermore, this dual-circularly polarized reflectarray antenna based on dual "S"-shaped printed metal strips is simple to fabricate and offers excellent performance, demonstrating promising application prospects in radar communications.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual circularly polarized reflectarray antenna, comprising a circularly polarized antenna feed (1) for transmitting spherical electromagnetic waves, and a dual "S"-shaped printed metal strip reflectarray (2) for receiving the spherical electromagnetic waves and reflecting them into plane waves; It is characterized in that The double "S"-shaped printed metal strip reflection array (2) is composed of a plurality of double "S"-shaped printed metal strip reflection units (3) arranged in an array; The circularly polarized antenna feed source (1) faces the double "S"-shaped printed metal strip reflective array (2) along the -z direction and is located at the phase shift focus of the double "S"-shaped printed metal strip reflective array (2).

2. The dual circularly polarized reflectarray antenna according to claim 1, It is characterized in that The double "S"-shaped printed metal strip reflective unit (3) comprises two perpendicular and orthogonal dielectric substrates, each of which is provided with two symmetrical semi-S-shaped printed metal strips; the two dielectric substrates are assembled in a plug-in manner to form two groups of cascaded "S"-shaped printed metal strips.

3. The dual circularly polarized reflectarray antenna according to claim 1, It is characterized in that In the double "S"-shaped printed metal strip reflection unit (3), the first group of "S"-shaped printed metal strips (4) and the second group of "S"-shaped printed metal strips (5) have the same size, which is the working center frequency wavelength; The first group of "S"-shaped printed metal strips (4) reflects left-handed circularly polarized waves and is located near one end of the circularly polarized antenna feed source, and the second group of "S"-shaped printed metal strips (5) reflects right-handed circularly polarized waves and is located far from one end of the circularly polarized antenna feed source.

4. The dual circularly polarized reflectarray antenna according to claim 3, It is characterized in that The positions of the two groups of "S"-shaped printed metal strips in each double "S"-shaped printed metal strip reflection unit (3) on the dielectric substrate are different. The specific position calculation steps are as follows: Step S1, calculate the reflection phase, the specific formula is: in, is the reflection phase of the i-th double "S" type printed metal strip reflection unit (3), i ranges from 1 to M×N; k is the propagation constant in free space; R i is the distance from the circular polarization antenna feed source 1 to the i-th double "S" type printed metal strip reflector unit (3); is the position vector of the i-th double "S"-shaped printed metal strip reflection unit (3); is the direction in which the antenna radiates the main beam; is a phase constant, representing the required phase shift value of the double "S" type printed metal strip reflective array (2); Step S2: The relationship between the position of the "S"-shaped printed metal strip on the dielectric substrate and the reflection phase is: Among them, dz and dz 1 Indicates the relative positions of two groups of "S"-shaped printed metal strips on the dielectric substrate.

5. The dual circularly polarized reflectarray antenna according to claim 1, It is characterized in that The double "S"-shaped printed metal strip reflection units (3) are arranged in an array, and the specific arrangement method includes: arranging a plurality of double "S"-shaped printed metal strip reflection units (3) in parallel in sequence along the x direction, and stacking a plurality of double "S"-shaped printed metal strip reflection units (3) in sequence along the y direction.

6. The dual circularly polarized reflectarray antenna according to claim 5, It is characterized in that The distance between the "S"-shaped printed metal strips between adjacent double "S"-shaped printed metal strip reflection units (3) in which the "S"-shaped printed metal strips are arranged in parallel in the x direction is recorded as a first distance; The distance between the "S"-shaped printed metal strips between the adjacent double "S"-shaped printed metal strip reflecting units (3) stacked in the y direction of the "S"-shaped printed metal strips is recorded as the second distance; The first distance is equal to the second distance.

7. Independent control method of radiation beam of dual circularly polarized reflectarray antenna, It is characterized in that For the first group of "S"-shaped printed metal strips (4), when the incident electromagnetic wave is a left-handed circularly polarized wave, the electric field vector When the electric field vector is in the +x direction, a current i is generated on the "S"-shaped printed metal strip. 1 When the electric field vector is in the +y direction, an electric field in the same direction as the current i is generated on the "S"-shaped printed metal strip. 1 The opposite current i 2 , the phase delays of the two cancel each other out, exciting equal-amplitude and opposite-direction currents on the "S"-shaped printed metal strip, which exhibits a wavelength resonance as a whole, and the left-hand circularly polarized wave is reflected; where λ is the wavelength of the working center frequency; When the incident electromagnetic wave is a right-hand circularly polarized wave, the electric field vector When the electric field vector is in the +y direction, a current i is generated on the "S"-shaped printed metal strip. 1 When the electric field vector is in the +x direction, an electric field in the same direction as the current i is generated on the "S"-shaped printed metal strip. 1 The opposite current i 2 , the two currents cancel each other out, and the entire structure exhibits a non-resonant transmission state.

8. The method for independently controlling the radiation beam of a dual circularly polarized reflectarray antenna according to claim 7, It is characterized in that For the second group of "S"-shaped printed metal strips (5), when the incident electromagnetic wave is a left-hand circularly polarized wave or a right-hand circularly polarized wave, the current generated on the first group of "S"-shaped printed metal strips (4) is opposite to that on the first group; in When the incident electromagnetic wave is a left-hand circularly polarized wave, the currents on the second group of "S"-shaped printed metal strips (5) are offset from each other, and the entire structure exhibits a non-resonant transmission state; When the incident electromagnetic wave is a right-hand circularly polarized wave, equal-amplitude and opposite-direction currents will be excited on the second group of "S"-shaped printed metal strips (5), and the whole will exhibit a wavelength resonance, and the right-hand circularly polarized wave will be reflected.

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