An active phased array antenna and a method for enhancing gain in a specific scanning angle domain.

Abstract

This invention belongs to the field of communication antenna technology and discloses an active phased array antenna and a method for improving gain in a specific scanning angle domain. The antenna includes an active phased array and a passive phased array. The active phased array is composed of 10×10 broadband circularly polarized phased array elements, and the passive phased array is composed of 14×14 broadband circularly polarized phased array elements. Each broadband circularly polarized phased array element consists of a feed layer, an inner patch layer, an outer radiating layer, and a metal isolation pillar. The gain improvement method includes controlling the feed phase difference of the passive array to synthesize an equiphase surface between the two arrays when scanning 25° and when scanning 0°, respectively. This invention designs a broadband circularly polarized antenna element operating in the C-band (5.6GHz~6.4GHz) that maintains excellent impedance matching characteristics (VSWR < 1.5) throughout the entire operating frequency band (5.6GHz~6.4GHz).

Description

Technical Field

[0001] This invention belongs to the field of communication antenna technology, specifically relating to an active phased array antenna and a method for improving gain in a specific scanning angle domain. Background Technology

[0002] In modern telemetry and communication systems, especially for monitoring and acquiring data from long-distance, highly dynamic targets (such as telemetry aircraft), extremely high demands are placed on the reliability and stability of the communication link. As a key node for information reception, the performance of the antenna system of the telemetry ground station directly determines the quality of telemetry data and its effective range. With the development of phased array antenna technology, due to its significant advantages such as rapid beam agility, multi-target tracking, high reliability, and the elimination of mechanical rotation, it has been widely applied in various advanced telemetry ground stations.

[0003] In practical telemetry missions, telemetry aircraft often need to operate in airspace far from ground stations. For example, when the straight-line distance between the aircraft and the ground telemetry station reaches approximately 300 kilometers, the aircraft's elevation angle relative to the ground station is usually extremely low, roughly only 1 degree. This "long-distance, low-elevation angle" communication scenario is one of the typical challenges faced by telemetry systems. At this time, the electromagnetic wave propagation path is long, facing not only significant free-space path loss but also severe effects from ground reflection, atmospheric attenuation, multipath effects, and background noise. This leads to a sharp drop in the signal-to-noise ratio (SNR) of the received signal, deterioration of the communication link quality, and even potential data interruption. Therefore, under these extreme conditions, extremely high requirements are placed on the gain of the telemetry ground station's receiving antenna to compensate for path loss as much as possible and ensure accurate and real-time reception of telemetry data.

[0004] However, many telemetry ground stations currently use planar phased array antennas that may not have fully considered the extreme requirements of operating at extremely low elevation angles during design or installation. For example, the planar phased array antenna used by a certain ground station has its array normal (or the designed direction of maximum beamwidth) tilted downwards at 25 degrees relative to the vertical direction. This means that the antenna's highest gain beam points to the airspace at a 25-degree tilt angle to the ground. When tracking a target 300 kilometers away with an elevation angle of only 1 degree, the phased array antenna needs to scan its beam from the 25-degree tilt direction to the horizontal direction (where the ground tilt angle decreases) by nearly 24 degrees (a larger angle scan relative to the array normal).

[0005] An inherent characteristic of planar phased array antennas is that when the antenna beam deviates from its array plane normal (i.e., during large-angle scanning), the antenna gain inevitably decreases significantly, potentially accompanied by beam broadening, increased sidelobe levels, and aperture effects. This gain loss is particularly severe at large scan angles. Furthermore, the phased array used in this telemetry station is an active phased array, and to minimize the number of channels and reduce costs, there are strict regulations regarding the number of array elements; increasing the number of elements cannot improve the array gain.

[0006] Therefore, in the above scenarios, when the active phased array antenna is forced to operate in a fixed scanning angle domain with an inclination angle of only 1 degree to the ground, its actual usable gain often cannot meet the link budget requirements of long-distance communication, becoming a key bottleneck restricting the improvement of telemetry distance and data rate.

[0007] In summary, addressing the issue of insufficient gain in existing planar active phased array antennas for long-distance, low-elevation-angle (e.g., 300km distance corresponds to 1 degree elevation angle) scenarios for telemetry ground stations, due to the need for large-angle scanning with the beam deviating from the optimal design direction, this study proposes a method to effectively improve the gain of active phased array antennas in the fixed scanning angle domain (especially in the 1-degree ground tilt direction). This method has significant theoretical and engineering application value for improving the reliability of telemetry communication links, expanding telemetry range, and ensuring the successful acquisition of critical telemetry data. Summary of the Invention

[0008] This invention aims to address the shortcomings of existing technologies and provides the following solutions:

[0009] An active phased array antenna includes: an active phased array and a passive phased array;

[0010] The active phased array is composed of 10×10 broadband circularly polarized phased array elements, and the passive phased array is composed of 14×14 broadband circularly polarized phased array elements.

[0011] The broadband circularly polarized phased array unit consists of a feed layer, an inner patch layer, an outer radiating layer, and metal isolation pillars.

[0012] Preferably, the power supply layer includes: a first dielectric substrate, a first adhesive layer, a second dielectric substrate, a second adhesive layer, a third dielectric substrate, a third adhesive layer, and a fourth dielectric substrate bonded together in sequence, as well as a first power supply port, a second power supply port, and metal power supply vias that connect metallized feed lines upward from each port.

[0013] Preferably, the inner patch layer consists of a lower metal patch and a fourth adhesive layer.

[0014] Preferably, the outer radiating layer is composed of an upper metal patch and a fifth dielectric substrate.

[0015] This invention also provides a method for improving the gain in a specific scanning angle domain of an active phased array antenna. The method, used to improve the scanning angle domain gain of the aforementioned active phased array antenna, includes the following steps:

[0016] For the active phased array antenna, by controlling the feed phase difference of the passive array, the active phased array and the passive array are combined into an equiphase surface when scanning 25° and scanning 0° respectively.

[0017] Preferably, the method for controlling the feed phase difference of the passive array includes:

[0018] Calculate the path difference between the rightmost broadband circularly polarized phased array element of the active phased array and the leftmost broadband circularly polarized phased array element of the passive phased array:

[0019] ,

[0020] Where d represents the path difference, h represents the phased array height, w represents half the length of the broadband circularly polarized phased array element, ∠b represents the angle between the line connecting the midpoint of the top surface of the rightmost broadband circularly polarized phased array element of the active phased array and the midpoint of the top surface of the leftmost broadband circularly polarized phased array element of the passive phased array, and the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array; ∠d represents the angle between the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array and the extension of the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array, and the angle bisector of the extension of the line connecting the top surface of the leftmost broadband circularly polarized phased array element of the passive phased array.

[0021] The feed phase difference is calculated based on the path difference:

[0022] ,

[0023] in, λ represents the feed phase difference, λ represents the wavelength corresponding to the unit's operating center frequency, f represents the operating center frequency, and c represents the speed of light.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention designs a broadband circularly polarized antenna unit operating in the C-band (5.6GHz~6.4GHz), maintaining excellent impedance matching characteristics (VSWR<1.5) throughout the entire operating frequency band (5.6GHz~6.4GHz). The choice of the C-band is beneficial for balancing propagation loss, equipment cost, and technological maturity, and it is also the mainstream frequency band currently used in telemetry. The broadband characteristics ensure that the system can support higher data transmission rates or adapt to various telemetry signal formats, enhancing the system's flexibility and compatibility. The circular polarization characteristics effectively suppress multipath effects and polarization mismatch losses common in long-distance, low-elevation propagation paths, significantly improving the signal-to-noise ratio (SNR) and link reliability of the received signal, ensuring accurate reception of telemetry data. This innovative structural design not only significantly improves the reliability of the ground telemetry system, but also enhances the system's adaptability to different communication protocols through broadband characteristics, providing a reliable technical solution for the next generation of aviation communication systems.

[0026] (2) This invention creatively combines active phased arrays with passive phased arrays. The active phased array provides basic beam control and signal amplification, while also handling full-angle scanning. The passive phased array acts as a gain enhancer, requiring no additional T / R components or complex feeding networks, and only operates when the active array scans at an elevation angle of -2° to 5° to the ground. This hybrid architecture can effectively focus and enhance the gain of electromagnetic waves from a specific direction through a passive array, while significantly reducing the number of active channels and greatly reducing the overall system cost and complexity (especially the T / R components). This successfully solves the problem of severe gain degradation of traditional single active phased arrays during large-angle scanning, ensuring the detection and tracking performance of distant targets.

[0027] (3) To ensure that the active and passive phased arrays can be superimposed in phase in the target direction to form a high-gain beam, this invention further proposes a phase compensation algorithm. This algorithm can accurately calculate and compensate for the phase deviation introduced by the path difference between the active and passive arrays, the array surface difference, and the propagation and reflection of electromagnetic waves in the passive array. By finely adjusting the excitation phase of the active array and the unit phase of the passive array, the electromagnetic waves radiated by both arrays can achieve phase matching in the target area with a ground tilt angle of -2° to 5°, thereby effectively synthesizing a high-gain beam. This algorithm not only ensures the accuracy and efficiency of beam synthesis but also helps to suppress the sidelobe level of the synthesized beam, further optimizing the overall radiation performance of the antenna. Attached Figure Description

[0028] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are 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 these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of an active phased array antenna according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the broadband circularly polarized phased array unit structure according to an embodiment of the present invention, wherein, Figure 2 (a) is a schematic diagram of the overall structure. Figure 2 (b) is the main view. Figure 2 (c) is the top view;

[0031] Figure 3 This is an embodiment of the present invention. Figure 2 Enlarged schematic diagram of the intermediate feed layer structure;

[0032] Figure 4 This is a schematic diagram of an active phased array according to an embodiment of the present invention, wherein, Figure 4 (a) is a schematic diagram of the whole. Figure 4 (b) is a top view;

[0033] Figure 5 This is a schematic diagram of a passive phased array according to an embodiment of the present invention, wherein, Figure 5 (a) is a schematic diagram of the whole. Figure 5 (b) is a top view;

[0034] Figure 6 This is a schematic diagram of an active phased array antenna structure according to an embodiment of the present invention, wherein, Figure 6 (a) is a schematic diagram of the whole. Figure 6 (b) is the front view;

[0035] Figure 7 This is a front view of the actual spatial orientation of the active phased array antenna according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the phase compensation algorithm calculation for an active phased array antenna according to an embodiment of the present invention;

[0037] Figure 9 This is an embodiment of the present invention. Figure 7 Enlarged view of a portion of the geometric relationship diagram of the middle unit;

[0038] Figure 10 This is a comparison diagram of the beam scanning results of the active phased array antenna and the active array only in this invention;

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Metal feed via; 2. Upper metal patch; 3. Lower metal patch; 4. Metallized via; 5. First dielectric substrate; 6. First adhesive layer; 7. Second dielectric substrate; 8. Second adhesive layer; 9. Third dielectric substrate; 10. Third adhesive layer; 11. Fourth dielectric substrate; 12. Fourth adhesive layer; 13. Fifth dielectric substrate; 14. Metallized feed line; 15. First feed port; 16. Second feed port; 17. Active phased array; 18. Passive phased array; 19. Hybrid array scanning direction; 20. An equiphase surface of the hybrid array when scanning 25°; 21. A cell in the active phased array adjacent to the passive phased array; 22. A cell in the passive phased array adjacent to the active phased array. Detailed Implementation

[0041] 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. 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.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1:

[0044] In this embodiment, as Figure 1 , Figure 2 , Figure 3 As shown, an active phased array antenna includes: an active phased array 17 and a passive phased array 18;

[0045] The active phased array 17 consists of 10×10 broadband circularly polarized phased array elements, while the passive phased array 18 consists of 14×14 broadband circularly polarized phased array elements. Each broadband circularly polarized phased array element comprises a feed layer, an inner patch layer, an outer radiating layer, and metal isolation pillars. The entire element has a height of 7.023 mm and a length and width of 26.3 mm.

[0046] The power supply layer includes: a first dielectric substrate 5, a first adhesive layer 6, a second dielectric substrate 7, a second adhesive layer 8, a third dielectric substrate 9, a third adhesive layer 10, and a fourth dielectric substrate 11 bonded together in sequence; a first power supply port 15; a second power supply port 16; and metal power supply vias 1 connecting metallized feed lines 14 upwards from each port. The inner patch layer is composed of a lower metal patch 3 and a fourth adhesive layer 12. The outer radiating layer is composed of an upper metal patch 2 and a fifth dielectric substrate 13. The metal isolation pillars are formed by metallized vias 4 surrounding the cell.

[0047] In this embodiment, the power supply layer includes a first power supply port 15, a second power supply port 16, and metal power supply vias 14 connecting metallized feed lines 14 upwards from each port. The metal power supply vias 15 have a radius of 0.5 mm, and the metallized feed lines 14 have a length of 1.7 mm. The power supply layer uses a first dielectric substrate 5, a second dielectric substrate 7, a third dielectric substrate 9, a fourth dielectric substrate 11, and a first adhesive layer 6, a second adhesive layer 8, and a third adhesive layer 10. The height of the first dielectric substrate 5, the second dielectric substrate 7, and the third dielectric substrate 9 is 1.524 mm, the height of the fourth dielectric substrate 11 is 0.127 mm, and the height of the first adhesive layer 6 ... the third dielectric substrate 9, the fourth dielectric substrate 11 is 0.127 mm, and the height of the fourth dielectric substrate 11 is 0.127 mm. The heights of the second adhesive layer 8 and the third adhesive layer 10 are 0.2 mm. When the antenna element is working, both ports are simultaneously fed with equal radiation. The initial phase of the first feed port 15 is set to 90°, and the initial phase of the second feed port 16 is set to 0°. The inner patch layer includes a lower metal patch 3 and a fourth adhesive layer 12. The lower metal patch 3 is square, with a length and width of 11 mm, and the fourth adhesive layer 12 has a height of 0.2 mm. The outer radiating layer includes an upper metal patch 2 and a fifth dielectric substrate 13. The upper metal patch 2 is square, with a length and width of 10.4 mm, and the fifth dielectric substrate 13 has a height of 1.524 mm. The dielectric constant of the dielectric substrate used in the antenna element is 2.2, and the dielectric constant of the adhesive layer used is 3.5.

[0048] The following is combined with Figure 4 The active phased array 17 according to an embodiment of this application is composed of 10×10 broadband circularly polarized phased array elements, with a length and width of 250mm and a height of 7.023mm. The phase of the feed port of each element is arbitrarily adjustable. By changing the feed phase of each element, beam scanning of 0° to ±65° can be achieved (the angle when the array is scanning vertically upward is defined as 0°).

[0049] The following is combined with Figure 5 The passive phased array 18 according to an embodiment of this application is composed of 14×14 broadband circularly polarized phased array elements, with a length and width of 300mm and a height of 7.023mm. The feed port of each element is a fixed value, which can only achieve beam pointing of 0° (i.e., the vertical upward angle of the array scan).

[0050] The following is combined with Figure 6 This application describes a hybrid active and passive phased array 18 according to an embodiment of the present application. The entire array consists of the aforementioned active phased array 17 and passive phased array 18. The active array is positioned along a horizontal line, and the passive array is located to the right of the active array, with a tilt angle of ∠a = 25° relative to the horizontal plane. This is to allow the passive array to specifically enhance the gain of the active array when scanning 25°. The passive array only operates when the active array scans 25°. In actual ground telemetry antenna design, it is necessary to follow... Figure 7 As shown, rotating the entire hybrid array 65° clockwise can meet the high-gain requirement of ground telemetry antennas scanning at low elevation angles (i.e., -2° to 5°). For the simulation of this hybrid array, the relative positions of the active and passive arrays remain unchanged regardless of the spatial orientation of the entire hybrid array. Therefore, it is only necessary to simulate the case where the active array is placed along a horizontal line.

[0051] Example 2:

[0052] In this embodiment, to ensure that the active phased array 17 and the passive phased array 18 can be superimposed in phase in the target direction to form a high-gain beam, the present invention further provides a method for improving the gain of an active phased array antenna in a specific scanning angle domain, including the following steps:

[0053] For active phased array antennas, by controlling the feed phase difference of the passive array, the active phased array 17 can be combined into an equiphase surface when scanning 25° and the passive array is scanning 0°. Figure 8 The diagram shows the beam direction of each element when the hybrid array is scanned along the hybrid array scanning direction 19 (25°) from a frontal view perspective. The top center of the element in the active phased array 17 and the passive phased array 18 is used as the reference point. The dashed line is an equiphase surface 20 of the hybrid array when scanning 25°. In the figure, d is the path difference between an element 21 in the active phased array that is adjacent to the passive phased array and an element 22 in the passive phased array that is adjacent to the active phased array.

[0054] like Figure 9 As shown, the method for controlling the feed phase difference of the passive array includes: calculating the path difference between the rightmost broadband circularly polarized phased array element of the active phased array 17 (an element 21 in the active phased array adjacent to the passive phased array) and the leftmost broadband circularly polarized phased array element of the passive phased array 18 (an element 22 in the passive phased array adjacent to the active phased array).

[0055] ,

[0056] Where d represents the path difference, h represents the phased array height, w represents half the length of the broadband circularly polarized phased array element, ∠b represents the angle between the line connecting the midpoint of the top surface of the rightmost broadband circularly polarized phased array element in the active phased array and the midpoint of the top surface of the leftmost broadband circularly polarized phased array element in the passive phased array, and the line connecting the top surface of the rightmost broadband circularly polarized phased array element in the active phased array; ∠d represents the angle between the line connecting the top surface of the rightmost broadband circularly polarized phased array element in the active phased array and the angle bisector of the extension of the line connecting the top surface of the rightmost broadband circularly polarized phased array element in the active phased array and the extension of the line connecting the top surface of the leftmost broadband circularly polarized phased array element in the passive phased array; ∠c represents the angle between the extension of the line connecting the top surface of the rightmost broadband circularly polarized phased array element in the active phased array and the extension of the line connecting the top surface of the leftmost broadband circularly polarized phased array element in the passive phased array; The feed phase difference is calculated based on the path difference:

[0057] ,

[0058] in, λ represents the feed phase difference, λ represents the wavelength corresponding to the unit's operating center frequency of 5.6 GHz, f represents the operating center frequency of 5.6 GHz, and c represents the speed of light.

[0059] If the feed phase of a cell 21 adjacent to a passive phased array in the active phased array 17 is ∅1 when the active phased array 17 scans 25°, then when the passive phased array 18 specifically improves the gain of the active phased array 17 when scanning 25°, it needs to satisfy the feed phase of a cell 22 adjacent to the active phased array in the passive phased array ∅2=∅1+∆∅. At this time, beamforming of the passive phased array 18 and the active phased array 17 can be achieved, realizing the highest gain. At this time, for the passive phased array 18, the scanning direction is perpendicular to the array surface direction of the passive phased array 18, that is, the passive phased array 18 is scanning 0°. Therefore, the required feed phase of all cells in the array needs to be consistent with the feed phase of a cell 22 adjacent to the active phased array in the passive phased array.

[0060] Figure 10 This is a comparison diagram of the beam directions of the active phased array 17 and the hybrid array at a frequency of 6 GHz in this embodiment. Figure 10 It can be seen that the gain of the active phased array 17 alone is 24.32 dBic when scanning at a 25° angle; however, when the active phased array 17 and the passive phased array 18 are combined into a hybrid array, the maximum gain of the array increases from 24.32 dBic to 29.17 dBic, an increase of 4.85 dBic. This performance fully meets the requirements of ground telemetry systems for high gain at low elevation angles, and ensures the stability of the communication link without significantly increasing the number of digital channels.

[0061] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An active phased array antenna, characterized in that, include: Active phased arrays and passive phased arrays; The active phased array is composed of 10×10 broadband circularly polarized phased array elements, and the passive phased array is composed of 14×14 broadband circularly polarized phased array elements. The broadband circularly polarized phased array unit consists of a feed layer, an inner patch layer, an outer radiating layer, and metal isolation pillars. The method for enhancing the gain in a specific scanning angle domain for the active phased array antenna includes the following steps: For the active phased array antenna, by controlling the feed phase difference of the passive phased array, the two arrays are combined into an equiphase surface when the active phased array scans 25° and when the passive phased array scans 0°. The method for controlling the feed phase difference of a passive phased array includes: Calculate the path difference between the rightmost broadband circularly polarized phased array element of the active phased array and the leftmost broadband circularly polarized phased array element of the passive phased array: ， Where d represents the path difference, h represents the phased array height, w represents half the length of the broadband circularly polarized phased array element, ∠b represents the angle between the line connecting the midpoint of the top surface of the rightmost broadband circularly polarized phased array element of the active phased array and the midpoint of the top surface of the leftmost broadband circularly polarized phased array element of the passive phased array, and the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array; ∠d represents the angle between the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array and the extension of the line connecting the top surface of the rightmost broadband circularly polarized phased array element of the active phased array, and the angle bisector of the extension of the line connecting the top surface of the leftmost broadband circularly polarized phased array element of the passive phased array. The feed phase difference is calculated based on the path difference: ， in, λ represents the feed phase difference, λ represents the wavelength corresponding to the unit's operating center frequency, f represents the operating center frequency, and c represents the speed of light.

2. The active phased array antenna according to claim 1, characterized in that, The power supply layer includes: a first dielectric substrate, a first adhesive layer, a second dielectric substrate, a second adhesive layer, a third dielectric substrate, a third adhesive layer, and a fourth dielectric substrate bonded together in sequence, as well as a first power supply port, a second power supply port, and metal power supply vias that connect metallized feed lines upward from each port.

3. The active phased array antenna according to claim 1, characterized in that, The inner patch layer consists of a lower metal patch and a fourth adhesive layer.

4. The active phased array antenna according to claim 1, characterized in that, The outer radiating layer consists of an upper metal patch and a fifth dielectric substrate.

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