Quad-polarization and beam composite reconfigurable antenna array based on 1-bit control

Abstract

The application provides a four-polarization and beam composite reconfigurable antenna array based on 1bit control, and belongs to the technical field of antennas, and comprises M*N rectangular arranged microstrip patch antenna units and a feed network; the microstrip patch antenna units independently control the on-off of diodes through two bias lines, so as to realize 1bit phase regulation of X polarization and Y polarization; the feed network comprises a power divider and a delay line; the delay line is connected with the output end of the power divider and the input end of the microstrip feed line layer of the microstrip patch antenna unit respectively; each microstrip patch antenna unit has different initial phases by using delay lines with different lengths. The application low-costly eliminates the periodic phase error caused by 1bit control, constructs a four-polarization reconfigurable antenna array, and realizes the quick switching of polarization diversity and beam state.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, specifically to a four-polarization and beam-combined reconfigurable antenna array based on 1-bit control and its design method. Background Technology

[0002] A reconfigurable antenna is an antenna that can achieve different operating modes by changing its own operating state. Through proper design, the polarization, frequency, and radiation pattern of a reconfigurable antenna can be reconfigured. Currently, reconfiguration methods include electronic reconfiguration, mechanical reconfiguration, and modification of material properties. Compared to traditional phased arrays, reconfigurable antennas are characterized by lower cost, compact structure, and ease of diversity implementation, thus offering greater adaptability to various complex application scenarios.

[0003] In recent years, global communication technology has developed rapidly, accompanied by the deployment of various Internet of Things (IoT) devices (such as communication terminals, vehicle-mounted devices, sensor devices, smart homes, etc.). These devices have made people's lifestyles more convenient, but have also consumed a large amount of spectrum resources. Currently, polarization diversity, as a widely used diversity technology, can not only improve channel capacity and alleviate spectrum pressure, but also switch between online circular polarization working states according to different application scenarios to achieve the best working state, and therefore has received increasing attention. For example, the Chinese invention patent application No. 202010663171.8, "A Design Method for a Four-Polarization Reconfigurable Metasurface Antenna," obtains the corresponding holographic phase distribution map by controlling the on / off state of each slot element of the antenna array, realizing the radiation of beams with four polarizations. However, it does not consider how to eliminate the periodic phase error caused by 1-bit phase compensation. At the same time, traditional phased arrays can accurately control the array beam response through high-precision phase shifters. For dual-linear polarized phased arrays, left-hand or right-hand rotating beams can be synthesized by controlling the two orthogonal linear polarizations to generate a 90° phase difference. However, configuring a high-precision phase shifter for each antenna element would undoubtedly increase the system cost significantly. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to eliminate the periodic phase error caused by 1-bit control at low cost and construct a four-polarized reconfigurable antenna array.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] This invention provides a four-polarization and beam composite reconfigurable antenna array based on 1-bit control, including M×N rectangularly arranged microstrip patch antenna elements and a feeding network; the microstrip patch antenna elements achieve 1-bit phase modulation of X-polarization and Y-polarization by independently controlling the switching of diodes through two bias lines.

[0007] The power supply network includes a power divider and delay lines; the delay lines are respectively connected to the output terminal of the power divider and the input terminal of the microstrip feed layer of the microstrip patch antenna element; by using delay lines of unequal length, each microstrip patch antenna element has a different initial phase.

[0008] Furthermore, the microstrip patch antenna unit comprises, from bottom to top, a microstrip feed layer, a first dielectric layer, a metal ground layer, a second dielectric layer, a driving patch, a third dielectric layer, and a parasitic patch; the microstrip feed line runs along the bottom of the first dielectric layer and is fed to the antenna through a slot in the metal ground layer; the driving patch and the parasitic patch are printed on the second and third dielectric layers, respectively.

[0009] Furthermore, an air layer separates the second and third dielectric layers, and the height of the air layer is adjusted to achieve the best matching performance for the microstrip patch antenna element.

[0010] Preferably, the first layer medium is Rogers 5880 with a thickness of 0.254 mm.

[0011] Preferably, the second and third dielectric layers are made of 1mm Rogers 4003.

[0012] Furthermore, the length of each extension line is determined by the initial phase of the microstrip patch antenna element optimized by the particle swarm optimization algorithm.

[0013] Furthermore, the initial phase determination of the microstrip patch antenna element includes the following steps:

[0014] S1. The compensated phase of the m-th microstrip patch antenna element located at coordinates [x,y] is expressed as follows:

[0015] φ x =(-xsinθ0cosφ0-ysinθ0sinφ0)-φ m (1)

[0016] φ y =(-xsinθ0cosφ0-ysinθ0sinφ0)-φ m +φ dif (2)

[0017] Where φ x and φ y These are the compensation phases required for X-polarization and Y-polarization, φ m Let θ0 and φ0 be the initial phase of the element, respectively, and let φ0 be the azimuth and elevation angles of the desired beam. dif This represents the phase difference between X-polarization and Y-polarization;

[0018] S2. Determine the size of the antenna array, the position of the antenna elements, the required polarization of the antenna array, and the wave sweep angle, and design the fitness function according to the required performance indicators.

[0019] S3. Generate n sets of initial phases and n sets of initial velocities; where n is the population size of the particle swarm algorithm; set gen = 1;

[0020] S4. Calculate the required polarization and the compensation phase corresponding to the wave sweep angle using equations (1) and (2), and quantize the compensation phase; calculate the corresponding radiation pattern according to the array factor formula, and calculate the fitness according to the fitness function;

[0021] S5. Update the optimal fitness calculated for each individual to its own optimal fitness, and update the optimal fitness of all individuals to the optimal fitness of the population.

[0022] S6. Determine if gen is equal to the preset number of iterations. If it is, stop the optimization and continue to step S7; otherwise, update the individual velocity and the individual initial phase, and set gen = gen + 1, then return to step S4.

[0023] S7. Based on the above steps, obtain the optimized initial phase and calculate the delay line length of the m-th microstrip patch antenna element.

[0024] Furthermore, the fitness function is as follows:

[0025] fit=PSLL+C1*XPL (3)

[0026] Where PSLL is the sidelobe peak value, XPL is the cross-polarization level, and C1 is the proportional coefficient that adjusts the quantitative relationship between the two.

[0027] Furthermore, the matrix factor formula is as follows:

[0028]

[0029] Where Im is the excitation amplitude of the m-th element, n is the total number of elements, j is the imaginary unit, and φ m_x_bit and φ m_y_bit These are the compensation phases for the quantized X-polarization and Y-polarization, respectively, AF x (θ,φ) and AF y (θ,φ) are the radiation patterns of X-polarization and Y-polarization, respectively.

[0030] Furthermore, the delay line length of the m-th microstrip patch antenna element is calculated as follows:

[0031] l m =abs(mod(φ) m,360)-360)*2*π / (β*360) (6)

[0032] Where mod is the modulo operator, abs is the absolute value operator, and l m It is the delay line length corresponding to the m-th unit, φ m Let β be the initial phase of the m-th element, and β be the propagation constant of the microstrip line.

[0033] The advantages of this invention are:

[0034] The 1-bit reconfigurable dual-linear polarization unit designed in this invention eliminates the need for high-precision phase shifters, significantly reducing system cost. To address the issue of periodic phase errors caused by 1-bit phase compensation degrading beam performance, an extension line is introduced into the feed network to provide each unit with a different initial phase, breaking the periodicity of the phase error and improving beam scanning performance. To optimize array performance, a particle swarm optimization algorithm is used to refine the initial phase. Compared to traditional phased arrays, this scheme exhibits some degradation in gain and sidelobe performance, but significantly reduces cost. Furthermore, by omitting the phase shifter, the array size and weight are also smaller, making it a low-cost alternative to phased arrays. Attached Figure Description

[0035] Figure 1 A schematic diagram illustrating the working concept of a four-polarized reconfigurable antenna array according to an embodiment of the present invention;

[0036] Figure 2 This is an exploded view of a microstrip patch antenna element according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the layered cross-section of a microstrip patch antenna element according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the metal grounding layer structure of the microstrip patch antenna unit according to an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the bottom microstrip feed layer structure of the microstrip patch antenna unit according to an embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of a 2×8 quad-polarized reconfigurable array feed network according to an embodiment of the present invention;

[0041] Figure 7 This is a schematic diagram of the 3.95GHz circular polarization state radiation pattern and the change of the main polarization axial ratio gain with frequency in an embodiment of the present invention.

[0042] Figure 8 This is a schematic diagram of the 3.95GHz linear polarization state radiation pattern and the change of the main polarization gain with frequency, according to an embodiment of the present invention. Detailed Implementation

[0043] 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.

[0044] Four-polarized reconfigurable arrays hold great potential as a technology for improving channel capacity and communication quality. Controlling polarization and phase states using RF components such as PIN diodes can reduce system costs and make the entire system more compact. Furthermore, optimizing array parameters can enable the array to meet the requirements of polarization switching and beam deflection. This embodiment proposes a four-polarized and beam-combined reconfigurable antenna array based on 1-bit control, the working concept of which is as follows: Figure 1 As shown, each antenna controls the X-polarization and Y-polarization with a 1-bit phase shift using only diodes in the feed circuit, significantly reducing the cost of the antenna system. However, the periodic phase error caused by the 1-bit phase compensation leads to high sidelobes, and inaccurate phase compensation during circular polarization synthesis causes the orthogonal linear polarization phase difference to deviate from 90°, increasing the cross-polarization component. To address these issues, unequal-length delay lines are added to the power divider to give each element a different initial phase. This method breaks the periodicity of the phase error and improves the array's scanning performance. To assign the optimal initial phase to each antenna element, a particle swarm optimization algorithm is used to optimize the initial phase of each element. The final designed array can achieve four-polarization switching, with each polarization having a scanning range of -45 to +45 degrees, adapting to the communication needs of various complex scenarios.

[0045] This embodiment uses an array composed of 2×8 rectangularly arranged microstrip patch antenna elements as an example. Figure 6 As shown, it includes 2×8 rectangularly arranged microstrip patch antenna elements and a feeding network; the microstrip patch antenna elements independently control the on / off state of diodes through two bias lines to achieve 1-bit phase modulation of X polarization and Y polarization;

[0046] The power supply network includes a power divider and delay lines; the delay lines are respectively connected to the output terminal of the power divider and the input terminal of the microstrip feed layer of the microstrip patch antenna element; by using delay lines of unequal length, each microstrip patch antenna element has a different initial phase.

[0047] like Figures 2-6As shown, the microstrip patch antenna unit comprises, from bottom to top, a microstrip feed layer, a first dielectric layer, a metal ground layer, a second dielectric layer, a driver patch, a third dielectric layer, and a parasitic patch. The microstrip feed line runs along the bottom of the first dielectric layer, and the antenna is fed through a slot in the metal ground layer. The driver patch and parasitic patch are printed on the second and third dielectric layers, respectively. A diode is soldered onto the bottom microstrip line. An external DC control signal controls the switching of the diodes via a bias line, changing the current path to achieve 1-bit phase modulation of X and Y polarization.

[0048] The power supply network employs a Wilkinson power divider. The initial phase optimized by the particle swarm optimization algorithm can be mapped onto the delay line of the power divider to provide a different initial phase for each unit. The required compensation phase for each unit is calculated based on the optimized initial phase and quantized using 1 bit. The required compensation phase is achieved by switching an external DC control diode on and off.

[0049] In this embodiment, the first layer medium is Rogers 5880 with a thickness of 0.254 mm.

[0050] In this embodiment, the second and third dielectric layers are made of 1mm Rogers 4003.

[0051] The second and third dielectric layers are separated by an air layer. By adjusting the height of the air layer, the microstrip patch antenna element can achieve the best matching performance.

[0052] The length of each extension line is determined by the initial phase of the microstrip patch antenna element optimized using the particle swarm optimization algorithm. This includes the following steps:

[0053] S1. To achieve scanning beams with different polarizations, the compensation phase of the m-th microstrip patch antenna element located at coordinates [x,y] is expressed as follows:

[0054] φ x =(-xsinθ0cosφ0-ysinθ0sinφ0)-φ m (1)

[0055] φ y =(-xsinθ0cosφ0-ysinθ0sinφ0)-φ m +φ dif (2)

[0056] Where φ x and φ y These are the compensation phases required for X-polarization and Y-polarization, φ m Let θ0 and φ0 be the initial phase of the element, respectively, and let φ0 be the azimuth and elevation angles of the desired beam. difThis represents the phase difference between X and Y polarizations. When it is 0°, 180°, 90°, and -90°, it can synthesize +45° polarization, -45° polarization, left-hand circular polarization, and right-hand circular polarization, respectively. Since the designed antenna element can only perform 1-bit compensation for X and Y polarizations, the calculated compensation phase needs to be quantized 1 bit. When the required compensation phase is between 0 and 180°, the compensation phase is set to 0; when the required compensation phase is between 180° and 360°, the compensation phase is set to 180°.

[0057] Since 1-bit compensation has a large phase error, which will lead to a deterioration in beam performance, it is necessary to optimize the initial phase φ of each antenna element. m To ensure that the required beam configuration meets the design requirements.

[0058] S2. Determine the size of the antenna array, the position of the antenna elements, the required polarization of the antenna array, and the wave sweep angle. Design the fitness function based on the required performance indicators. The fitness function considering sidelobes and cross-polarization performance is as follows:

[0059] fit=PSLL+C1*XPL (3)

[0060] Where PSLL is the sidelobe peak value, XPL is the cross-polarization level, and C1 is the proportional coefficient that adjusts the quantitative relationship between the two.

[0061] S3. Generate n sets of initial phases and n sets of initial velocities; where n is the population size of the particle swarm algorithm; set gen = 1;

[0062] S4. Calculate the required polarization and the compensation phase corresponding to the wave sweep angle using equations (1) and (2), and quantize the compensation phase; calculate the corresponding radiation pattern according to the array factor formula, and calculate the fitness according to the fitness function; the array factor formula is as follows:

[0063]

[0064] Where Im is the excitation amplitude of the m-th element, n is the total number of elements, j is the imaginary unit, and φ m_x_bit and φ m_y_bit These are the compensation phases for the quantized X-polarization and Y-polarization, respectively, AF x (θ,φ) and AF y (θ,φ) are the radiation patterns of X-polarization and Y-polarization, respectively.

[0065] S5. Update the optimal fitness calculated for each individual to its own optimal fitness, and update the optimal fitness of all individuals to the optimal fitness of the population.

[0066] S6. Determine if gen is equal to the preset number of iterations. If it is, stop the optimization and continue to step S7; otherwise, update the individual velocity and the individual initial phase, and set gen = gen + 1, then return to step S4.

[0067] S7. After obtaining the optimized initial phase using the particle swarm optimization algorithm, the corresponding extension line length can be calculated based on the obtained initial phase, and the array can be simulated and verified using the full-wave simulation software High Frequency Structure Simulator (HFSS). If the simulation results meet the design requirements, the design is complete; otherwise, the particle swarm optimization algorithm is repeated for a new round of optimization. Finally, based on the optimized initial phase obtained from the above steps, the delay line length of the m-th microstrip patch antenna element is calculated as follows:

[0068] l m =abs(mod(φ) m ,360)-360)*2*π / (β*360) (6)

[0069] Where mod is the modulo operator, abs is the absolute value operator, and l m It is the delay line length corresponding to the m-th unit, φ m Let β be the initial phase of the m-th element, and β be the propagation constant of the microstrip line.

[0070] This embodiment achieves polarization switching and beam scanning functions by independently adjusting the phases of X and Y polarizations. As shown in formulas (1) and (2), through φ dif Beam switching is achieved by adjusting the phase difference between X and Y polarizations. To achieve good beam scanning performance even with 1-bit phase compensation, a delay line is added to the feed network to provide a different initial phase for each antenna element. This method breaks the periodicity of phase error caused by 1-bit phase compensation, thereby optimizing scanning performance. To further obtain the optimal initial phase distribution, a particle swarm optimization algorithm is used to optimize the initial phase so that the scanning beam performance meets the design requirements.

[0071] This embodiment presents a simulation test of the designed four-polarization and beam reconfigurable antenna array based on 1-bit control. The results are as follows: Figure 7 and Figure 8As shown, for a beam configuration of 0-45 degrees, the 3dB axial ratio bandwidth of both left-hand and right-hand circularly polarized beams can cover 3.7GHz-4.2GHz. This demonstrates that despite the relatively low phase resolution of the designed reconfigurable antenna, good circularly polarized beams can still be synthesized through dual-line polarization by optimizing the initial phase. Compared to continuously phase-tuned phased arrays, the sidelobes of the synthesized beam produced by this method are slightly increased, but remain below -7dB, offering a significant advantage over other low-phase-resolution scanning arrays.

[0072] 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 four-polarization and beam-combined reconfigurable antenna array based on 1-bit control, characterized in that: It includes M×N rectangularly arranged microstrip patch antenna elements and a feeding network; the microstrip patch antenna elements independently control the on / off state of diodes through two bias lines to achieve 1-bit phase modulation of X polarization and Y polarization; The feed network includes a power divider and delay lines; the delay lines are respectively connected to the output terminal of the power divider and the input terminal of the microstrip feed layer of the microstrip patch antenna element; by using delay lines of unequal length, each microstrip patch antenna element has a different initial phase. The initial phase determination of a microstrip patch antenna element includes the following steps: S1. The compensated phase of the m-th microstrip patch antenna element located at coordinates [x,y] is expressed as follows: in and These are the compensation phases required for X-polarization and Y-polarization, respectively. This is the initial phase of the unit. and These are the azimuth and elevation angles of the desired beam, respectively. This represents the phase difference between X-polarization and Y-polarization; S2. Determine the size of the antenna array, the position of the antenna elements, the required polarization of the antenna array, and the wave sweep angle, and design the fitness function according to the required performance indicators. S3. Generate n sets of initial phases and n sets of initial velocities; where n is the population size of the particle swarm algorithm; set gen=1; S4. Calculate the required polarization and the compensation phase corresponding to the wave sweep angle using equations (1) and (2), and quantize the compensation phase; calculate the corresponding radiation pattern according to the array factor formula, and calculate the fitness according to the fitness function; S5. Update the optimal fitness calculated for each individual to its own optimal fitness, and update the optimal fitness of all individuals to the optimal fitness of the population. S6. Determine if gen is equal to the preset number of iterations. If it is, stop the optimization and continue to step S7; otherwise, update the individual velocity and the individual initial phase, and set gen=gen+1, then return to step S4. S7. Based on the above steps, obtain the optimized initial phase and calculate the delay line length of the m-th microstrip patch antenna element.

2. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 1, characterized in that: The microstrip patch antenna unit comprises, from bottom to top, a microstrip feed layer, a first dielectric layer, a metal ground layer, a second dielectric layer, a driving patch, a third dielectric layer, and a parasitic patch; The first layer of dielectric material has a microstrip feed line running at the bottom, and the antenna is fed through a gap in the metal grounding layer; The driving patch and the parasitic patch are printed on the second and third media, respectively.

3. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 2, characterized in that: The second and third media layers are separated by an air layer, the height of which is adjustable.

4. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 2, characterized in that: The first layer of medium used was Rogers 5880 with a thickness of 0.254 mm.

5. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 2, characterized in that: The second and third dielectric layers use 1mm Rogers 4003.

6. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 1, characterized in that: The length of each extension line is determined by the initial phase of the microstrip patch antenna element optimized by the particle swarm optimization algorithm.

7. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 1, characterized in that: The fitness function is as follows: Where PSLL is the sidelobe peak value, XPL is the cross-polarization level, and C1 is the proportional coefficient that adjusts the quantitative relationship between the two.

8. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 1, characterized in that: The formula for the array factor is as follows: Among them I m Let n be the excitation amplitude of the m-th unit, n be the total number of units, and j be the imaginary unit. and These are the compensation phases for the quantized X-polarization and Y-polarization, respectively. and These are the radiation patterns for X-polarization and Y-polarization, respectively; x m Let x be the x-coordinate of the m-th unit, and y be the x-coordinate of the m-th unit. m Let y be the y-coordinate of the m-th unit.

9. The four-polarization and beam-combined reconfigurable antenna array based on 1-bit control according to claim 1, characterized in that: The delay line length of the m-th microstrip patch antenna element is calculated as follows: Where mod is the modulo operator and abs is the absolute value operator. It is the length of the delay line corresponding to the m-th unit. Let m be the initial phase of the m-th unit. It is the propagation constant of the microstrip line.

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