A pseudo virtual element method for small scale tightly coupled electrically scanned arrays

Abstract

The application discloses a pseudo-virtual element method for a small-scale tightly-coupled electric scanning array, which comprises the following steps: S1, performing period boundary debugging and determining basic unit parameters; S2, establishing a complete array comprising effective units (1) and pseudo-virtual elements (2), and performing small signal feeding on the pseudo-virtual elements (2) to determine the size of the pseudo-virtual elements (2) and small signal power; S3, setting the input impedance of the pseudo-virtual elements (2) as Z1, setting the input impedance of the effective units (1) as Z2, simultaneously connecting the virtual elements without adjacent effective units (1) to a preset load as real virtual elements (3), simulating the complete array, and fine-tuning structure parameters and the size of a power divider (4) to complete the design. The application can significantly suppress the performance deterioration caused by the edge effect, improve low-frequency standing wave and radiation performance, maintain array phase consistency and scanning performance, and is suitable for super wideband small-scale tightly-coupled electric scanning arrays and has strong engineering implementation.

Description

Technical Field

[0001] This invention relates to the field of array antenna technology, and in particular to a pseudo-virtual element method applicable to small-scale tightly coupled electronically scanned arrays. Background Technology

[0002] Ultra-wideband tightly coupled array antennas are widely used in broadband communication, broadband radar, and electronic countermeasures systems. To avoid grating lobes in the high-frequency electronically scanned radiation pattern, the element spacing is usually determined by the highest operating frequency. In the low-frequency band, a small element spacing causes the array's physical aperture to be much smaller than the operating wavelength, resulting in severe array edge effects, impedance mismatch, VSWR degradation, and decreased radiation efficiency, seriously limiting the array's low-frequency performance. This phenomenon is particularly pronounced in small-scale arrays.

[0003] Traditional array antenna design involves optimizing individual elements using periodic boundaries and then directly applying the results to finite array simulations. However, due to the significant environmental differences between edge and center elements, the superior performance at the element level cannot be maintained across the entire array. Conventional virtual elements serve only as boundary fillers and do not participate in feeding or energy distribution, offering limited improvement to the edge field. Increasing the number of effective elements increases the array aperture, cost, and system complexity, making it difficult to meet miniaturization and lightweight design requirements.

[0004] Therefore, there is an urgent need for a pseudo-virtual element method that can significantly suppress edge effects and extend low-frequency operating bandwidth of small-scale tightly coupled electro-scan arrays without increasing the number of effective ports or changing the effective cell spacing and arrangement. Summary of the Invention

[0005] This invention provides a pseudo-virtual element method for small-scale tightly coupled electro-scan arrays to solve the technical problems of significant low-frequency edge effects and poor matching performance in existing small-scale tightly coupled electro-scan arrays.

[0006] This invention is achieved using the following technical solution: a pseudo-virtual element method applicable to small-scale tightly coupled electronically scanned arrays, comprising the following steps: S1: Debugging and determining basic element parameters based on periodic boundaries; S2: Establish a complete array containing effective cells and pseudo-virtual elements, and perform small-signal feeding on the pseudo-virtual elements to determine the pseudo-virtual element size and small-signal power; S3: Set the pseudo-virtual element input impedance to Z1 and the corresponding effective element input impedance to Z2. At the same time, connect the virtual element without adjacent effective elements to the preset load as the true virtual element. Simulate the complete array and fine-tune the structural parameters and power divider size to complete the design.

[0007] Furthermore, the basic unit parameters include one or more of the following: operating frequency band, element spacing, array size, polarization mode, scanning range, and unit type.

[0008] Furthermore, the parameters of the effective units remain consistent, with the same parameters used for virtual elements in the x-direction and the same parameters used for virtual elements in the y-direction.

[0009] Furthermore, the pseudo-virtual elements in the x and y directions need to be configured with power dividers to obtain power supply, and the port impedance of the power divider must satisfy: Z2 / Z1 = P1 / P2; Where Z1 is the impedance of the virtual element port, Z2 is the impedance of the effective element port, P1 is the virtual element power, and P2 is the effective element power.

[0010] Furthermore, the power divider consists of a folded copper rod, copper sheet, Teflon dielectric, housing, and a first RF connector; the copper rod and copper sheet are respectively connected to the active unit and the pseudo-virtual element through pins.

[0011] Furthermore, the effective unit feed is equipped with a phase balance segment to ensure that the edge effective units and the center effective units remain in phase.

[0012] Furthermore, the phase balance segment is composed of a coaxial straight segment, which consists of a straight copper rod, a hollow Teflon dielectric cylinder, a straight outer shell, and a second RF connector.

[0013] Furthermore, one end of the phase balance line segment is connected to the outside via a second RF connector, and the other end is directly inserted into the antenna via a pin to achieve matching. The pin is connected to a straight copper rod.

[0014] Furthermore, both the effective units and the pseudo-virtual units require different parameter optimizations.

[0015] Furthermore, the virtual element not connected to the power divider is a true virtual element, and the true virtual element needs to be connected to a 50Ω matched load.

[0016] The beneficial effects of this invention are as follows: This invention addresses the significant low-frequency edge effects and matching degradation issues in ultra-wideband small-scale arrays. Without increasing the number of effective elements and ports, it optimizes the pseudo-virtual element size and utilizes a miniaturized T-junction power divider to couple and distribute the energy of the effective elements to the virtual elements, while adjusting the port impedance to achieve good matching across the entire array.

[0017] This invention can significantly suppress edge effects, improve low-frequency standing wave and radiation performance, maintain array phase consistency and scanning performance, and is suitable for ultra-wideband small-scale tightly coupled electronically scanned arrays. It is highly feasible in engineering implementation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 Side view of the present invention Figure 1 ; Figure 3 Side view of the present invention Figure 2 ; Figure 4 A diagram showing the power distribution of the array cells; Figure 5 This is a schematic diagram of the impedance distribution at the array ports. Figure 6 This is a diagram showing the connection structure between the pseudo-virtual element and the power divider. Figure 7 Internal structure diagram of a power divider; Figure 8 This is a diagram of the internal structure of the phase-matching straight line segment; In the diagram, 1-effective unit; 2-pseudo-virtual element; 3-true virtual element; 4-power divider; 4_1-copper sheet; 4_2-copper rod; 4_3-Teflon dielectric; 4_4-shell; 4_5-first RF connector; 5-phase balance line segment; 5_1-straight copper rod; 5_2-Teflon dielectric cylinder; 5_3-straight shell; 5_4-second RF connector; 6-load. Detailed Implementation

[0020] 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 with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0023] See Figures 1 to 81. A pseudo-virtual element method applied to small-scale tightly coupled electronically scanned arrays, comprising the following steps: S1: Debugging and determining basic element parameters based on periodic boundaries; S2: Establish a complete array containing effective element 1 and pseudo-virtual element 2. The parameters of effective element 1 are kept consistent. The virtual elements in the x direction use the same parameters, and the virtual elements in the y direction use the same parameters. The pseudo-virtual element 2 is fed with a small signal. The entire array is optimized to determine the virtual element size and small signal power. S3: Set the input impedance of pseudo-virtual element 2 to Z1, and the input impedance of the corresponding effective element 1 to Z2. At the same time, connect the virtual element without adjacent effective element 1 to a 50Ω impedance as the true virtual element 3. Fine-tune the entire array simulation to complete the design.

[0024] For details, please refer to Figures 1 to 3 , Figure 1 The diagram shows the overall appearance structure of this embodiment from a frontal oblique top view. In the diagram, the x-direction is the polarization direction and the z-normal direction is the beam pointing direction, i.e., the normal direction. Figure 2 This illustrates the structural differences between the effective polarization direction elements and pseudo-virtual elements in this embodiment, specifically in the x-direction; Figure 3 The structural differences between the effective unit and the pseudo-virtual element in the non-polarized direction of this embodiment are shown, namely in the y-direction.

[0025] In this embodiment, the array operates in an ultra-wideband frequency band, and the array size consists of 1 effective element plus one pseudo-circle of virtual elements (i.e., true virtual elements 3), supporting electronic scanning requirements.

[0026] In this embodiment, the effective unit 1 and the pseudo virtual element 2 need to be optimized with different parameters.

[0027] In this embodiment, pseudo-virtual elements 2 in the x and y directions need to be configured with power dividers 4 to obtain power supply. The port impedance of power divider 4 satisfies: Z2 / Z1=P1 / P2, where Z1 is the port impedance connected to the virtual element, Z2 is the port impedance connected to the effective unit, P1 is the virtual element power, and P2 is the effective unit power.

[0028] In this embodiment, a phase balancing segment 5 is added to the power supply of the central effective unit 1 to keep the edge effective units in phase with the central effective unit. The phase balancing segment 5 consists of a coaxial straight segment, which is composed of a straight copper rod 5_1, a hollow Teflon dielectric cylinder 5_2, a straight outer shell 5_3, and a second RF connector 5_4. Other conceivable solutions for achieving phase balance, such as microstrip lines, are also possible. See [link to documentation]. Figure 8 One end of the phase balance line segment 5 is connected to the outside via the second RF connector 5_4, and the other end is a pin that can be directly inserted into the antenna to achieve matching.

[0029] In this embodiment, the output port of power divider 4 is not converted to 50Ω, reducing the additional size caused by impedance conversion. See also Figure 7 The power divider 4 consists of a folded copper rod 4_2, a copper sheet 4_1, a Teflon dielectric 4_3, a housing 4_4, and a first RF connector 4_5. Other conceivable power distribution solutions, such as microstrip line power dividers, stripline power dividers, and waveguide power dividers, can also be used. One end of the power divider 4 is connected to the outside via the first RF connector 4_5, and the other end has two pins that are inserted into the active element 1 and the pseudo-virtual element 2 respectively for matching. The virtual element not connected to the power divider 4 is the true virtual element 3, connected to a 50Ω matching load 6.

[0030] The present invention will be further described below with reference to a specific embodiment.

[0031] The parameters include: operating frequency band: 0.2–2 GHz; element spacing: 75 mm × 75 mm; array size: 8 × 8 + one ring of virtual elements; polarization: single-line polarization; scanning range: ±25°; element type: metal Vivaldi antenna.

[0032] A periodic boundary element model was established in the full-wave simulation software. Parameters such as Vivaldi groove line, gradient width, and floor height were optimized to ensure that the active standing wave ratio of the element is better than 2.0 in the 0.2–2 GHz range, the electronically scanned active standing wave ratio is less than 3.0, and the radiation pattern meets the requirements.

[0033] A finite array model with 8×8 effective elements and an outer ring of virtual elements is established. Virtual elements in the x and y directions have the same size. A small-signal feed is applied to the virtual elements. The width, length, and coupling power of the virtual elements are optimized with the goal of improving full-band standing wave ratio, gain, and scanning performance.

[0034] The virtual element port impedance is set to Z1, and the corresponding effective element port impedance is set to Z2. At the same time, the virtual element without adjacent effective elements is connected to a 50Ω impedance as a true virtual element. The entire array is simulated and the structural parameters and power divider size are finely adjusted to achieve the required VSWR, gain, and scanning performance of the entire array.

[0035] Design a miniaturized 1-to-2 T-junction power divider. The power distribution ratio is determined through simulation, and the port impedance is determined based on the impedance relationship Z2 / Z1=P1 / P2, without performing a 50Ω impedance conversion. The power divider consists of a folded copper rod, copper sheets, Teflon dielectric, a housing, and an RF connector. One end of the power divider has an RF connector for external connection, and the other end has two pins that are inserted into the active cell and pseudo-virtual cell respectively for matching.

[0036] To compensate for the phase difference introduced by the power divider, a coaxial straight segment is added to the feed section of the center effective element to ensure phase consistency across the entire array. The coaxial straight segment consists of a copper rod, a hollow Teflon-coated cylinder, a housing, and an RF connector. The end of the copper rod facing the antenna is optimized and inserted inside the antenna to achieve impedance matching.

[0037] Simulation results show that after adopting this pseudo-virtual element technology, the VSWR of the array in the 0.2GHz low-frequency band is significantly improved, the radiation efficiency is enhanced, and there is no obvious distortion in the ±25° scanning pattern, which meets the requirements for use in ultra-wideband small-scale arrays.

[0038] For details, please refer to Figures 4 to 6 ,in, Figure 4 The power distribution diagrams of effective unit 1, pseudo virtual element 2, and true virtual element 3 in this embodiment are shown. Figure 5 The port impedance distribution diagrams of effective unit 1, pseudo-virtual element 2, and true virtual element 3 in this embodiment are shown. Figure 6 The diagram shows the overall appearance and structure of this embodiment from the bottom view, clearly illustrating the connection method between the power divider, the straight segment, and the 50Ω load and the unit.

[0039] Based on the above embodiments, the present invention has at least the following technical effects: 1. Without increasing the number of effective elements or changing the element spacing and feed port position, it significantly suppresses edge effects in small-scale arrays and improves low-frequency matching and radiation performance; 2. It adopts a miniaturized T-junction power divider to achieve directional energy coupling distribution, which is compact and easy to integrate; 3. It ensures the amplitude and phase consistency of the entire array through phase balance design, and the electronically scanned radiation pattern has no obvious distortion; 4. It is suitable for ultra-wideband small-scale tightly coupled arrays such as Vivaldi, and can be directly compatible with existing array design processes, making it highly feasible in engineering.

[0040] For the foregoing embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to this application.

[0041] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Modifications and variations made by those skilled in the art without departing from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. A pseudo-virtual element method applicable to small-scale tightly coupled electro-scan arrays, characterized in that, Includes the following steps: S1: Debugging and determining basic element parameters based on periodic boundaries; S2: Establish a complete array containing effective elements (1) and pseudo-virtual elements (2), and perform small-signal feeding on pseudo-virtual elements (2) to determine the size and small-signal power of pseudo-virtual elements (2); S3: Set the input impedance of the pseudo-virtual element (2) to Z1 and the input impedance of the corresponding effective element (1) to Z2. At the same time, connect the virtual element without adjacent effective element (1) to the preset load as the true virtual element (3). Simulate the complete array and fine-tune the structural parameters and the size of the power divider (4) to complete the design.

2. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 1, characterized in that, The basic unit parameters include one or more of the following: operating frequency band, element spacing, array size, polarization mode, scanning range, and unit type.

3. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 1, characterized in that, The parameters of the effective unit (1) remain consistent, with the same parameters used for the virtual elements in the x direction and the same parameters used for the virtual elements in the y direction.

4. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 3, characterized in that, The pseudo-virtual element (2) in the x and y directions needs to be configured with a power divider (4) to obtain power supply. The port impedance of the power divider (4) satisfies: Z2 / Z1 = P1 / P2; Where Z1 is the impedance of the virtual element port, Z2 is the impedance of the effective element port, P1 is the virtual element power, and P2 is the effective element power.

5. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 4, characterized in that, The power divider (4) consists of a folded copper rod (4_2), a copper sheet (4_1), a Teflon dielectric (4_3), a housing (4_4), and a first radio frequency connector (4_5); the copper rod (4_2) and the copper sheet (4_1) are respectively connected to the effective unit (1) and the pseudo virtual element (2) through pins.

6. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 1, characterized in that, The effective unit (1) is fed with an additional phase balance line segment (5) so that the edge effective unit and the center effective unit remain in phase.

7. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 6, characterized in that, The phase balance line segment (5) is composed of a coaxial straight line segment, which consists of a straight copper rod (5_1), a hollow Teflon dielectric cylinder (5_2), a straight shell (5_3), and a second radio frequency connector (5_4).

8. The pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in claim 7, characterized in that, One end of the phase balance line segment (5) is connected to the outside through the second radio frequency connector (5_4), and the other end is directly inserted into the antenna through a pin to achieve matching. The pin is connected to the straight copper rod (5_1).

9. A pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in any one of claims 1 to 8, characterized in that, Both the effective unit (1) and the pseudo virtual unit (2) require different parameter optimizations.

10. A pseudo-virtual element method for small-scale tightly coupled electro-scan arrays as described in any one of claims 1 to 8, characterized in that, The virtual element that is not connected to the power divider (4) is a true virtual element (3), and the true virtual element (3) needs to be connected to a 50Ω matching load (6).

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