Tight coupling array with broadband high-performance electromagnetic structure loaded at tail end

Abstract

The invention belongs to the technical field of microwave antennas, and particularly relates to a tight coupling array with a broadband high-performance electromagnetic structure loaded at the tail end, and the related broadband high-performance electromagnetic structure can be used for inhibiting the edge truncation effect of the broadband high-performance electromagnetic structure. The tight coupling array comprises three main parts: a broadband matching structure (I) which is formed by an electromagnetic metasurface loaded on a broadband efficient electromagnetic structure; the radiation structure (II) comprises a metal supporting arm of a front metal dipole and a gradually-changed metal support adopted by a rear metal dipole; and the feed structure (III) comprises a gradient micro-strip feeder line, a grounding plate and a coaxial cable. The antenna is suitable for various application scenes such as an electronic countermeasure system and a high-speed aircraft platform. The antenna shows good impedance matching characteristics and stable radiation performance in a wide frequency band, and effectively improves the performance degradation problem of a traditional tight coupling array at a boundary due to a truncation effect. According to the design, the structural integration level is considered while the radiation efficiency is guaranteed, and the antenna is suitable for occasions where the antenna size and the electrical performance are strictly limited, and has a relatively high engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically providing a tightly coupled array with an end-loaded broadband high-performance electromagnetic structure. Background Technology

[0002] In wireless communication and radar system design, key performance indicators such as information transmission rate, communication range, and airspace coverage are crucial. To optimize antenna performance, phased array technology combining ultra-wideband and wide-angle scanning has been widely researched and applied. Traditional ultra-wideband phased array design methods typically rely on individual antenna elements with broadband characteristics, which are then arrayed together. However, as the array size increases, the reduction in element spacing significantly enhances the mutual coupling effect between elements, leading to a decline in antenna performance, typically manifested as narrowing of the operating bandwidth and deterioration of scanning characteristics.

[0003] To mitigate the negative effects of mutual coupling, common techniques include defective ground structures, planar resonators, coupling field cancellation methods, and polarization deflection isolators. While these methods can alleviate mutual coupling to some extent, they often come at the cost of increased structural complexity, hindering the miniaturization and integration of antenna systems. In contrast, tightly coupled antennas cleverly utilize the strong coupling effect between elements as a mechanism to extend bandwidth, thereby achieving ultra-wideband performance without introducing additional decoupling structures.

[0004] As early as 1965, Wheeler proposed the theory of the "infinite current sheet," the core idea of ​​which is to divide the radiation space in front of the antenna array into parallel waveguides or equivalent transmission channels, and approximate the radiation behavior of the infinite current sheet by connecting dipole arrays of finite size. Based on this theory, tightly coupled phased arrays enhance the electromagnetic coupling between elements by minimizing the element spacing, thereby simultaneously achieving superior characteristics such as wide-angle scanning, ultra-wideband operation, and low-profile structure, becoming one of the important ways to realize modern high-performance antenna systems. Summary of the Invention

[0005] The purpose of this invention is to fill the technological gap in the field of broadband high-efficiency electromagnetic structure tightly coupled phased array antennas. It proposes a tightly coupled array with an end-loaded broadband high-performance electromagnetic structure, which aims to effectively suppress the edge truncation effect that is common in traditional tightly coupled arrays, thereby improving the overall antenna performance.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] This tightly coupled array mainly consists of four parts: a wide-angle matching layer, a broadband high-efficiency electromagnetic structure, a feeding structure, and a metal ground plane. The wide-angle matching layer is located on the upper surface of the dielectric substrate, while the broadband high-efficiency electromagnetic structure is arranged on the lower surface. Based on the tightly coupled array design concept, the broadband high-efficiency electromagnetic structure fully utilizes the strong electromagnetic coupling effect between units to achieve excellent broadband operating characteristics. Loading microstrip lines onto the broadband high-efficiency electromagnetic structure is equivalent to introducing parallel resistive and inductive components, effectively compensating for the excessive capacitive reactance of the array's end units caused by array truncation, thereby significantly improving impedance matching and suppressing edge effects.

[0008] The feed section employs a tapered microstrip line structure, with its linewidth continuously varying along the signal transmission direction. This achieves a smooth impedance transition from the feed port to the radiator, overcoming a key technical challenge in broadband matching. A metal ground plane is positioned beneath the tapered microstrip line, serving to provide electromagnetic shielding and suppress back radiation.

[0009] The innovation of this invention lies in:

[0010] I. By coordinating the design of a wide-angle scanning matching layer and a broadband high-efficiency electromagnetic structure, the antenna maintains good impedance matching characteristics over a wide frequency band, while also improving the problem of array performance degradation caused by edge stage effects.

[0011] Second, this invention replaces the dipoles in the edge units of a traditional finite array with a broadband, high-efficiency electromagnetic structure, and introduces parallel resistance and inductance components into the equivalent circuit model. This effectively compensates for the problem of excessive capacitive reactance of the end units caused by array truncation, thereby significantly improving impedance matching and suppressing edge effects. Attached Figure Description

[0012] Figure 1 This is an overall view of the 8×∞ tightly coupled array with a loaded broadband high-efficiency electromagnetic structure disclosed in an embodiment of the present invention;

[0013] Figure 2 This is a schematic diagram of a 4×∞ tightly coupled array of a loaded broadband high-efficiency electromagnetic structure disclosed in an embodiment of the present invention;

[0014] Figure 3 This is a front view of the unit feed structure of a tightly coupled array with an end-loaded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0015] Figure 4 This is a rear view of the unit feed structure of a tightly coupled array of an end-loaded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0016] Figure 5 This is a top view of the unit radiation structure of a tightly coupled array of an end-loaded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0017] Figure 6 This is a bottom view of the unit radiation structure of a tightly coupled array of an end-loaded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0018] Figure 7 This is a top view of the unit radiation structure of a tightly coupled array of an end-loaded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0019] Figure 8 This is a structural diagram of an array model where the end units are not loaded with a broadband high-performance electromagnetic structure, as disclosed in an embodiment of the present invention.

[0020] Figure 9 This is the active standing wave ratio curve of the array when the end unit is not loaded with a broadband high-performance electromagnetic structure, as disclosed in the embodiments of the present invention;

[0021] Figure 10 This is a model structure diagram of the array when the end unit is loaded with a broadband high-performance electromagnetic structure, as disclosed in an embodiment of the present invention;

[0022] Figure 11 The active standing wave ratio (VSWR) curve of the array when the end unit is loaded with a broadband high-performance electromagnetic structure, as disclosed in the embodiments of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and innovations of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and examples.

[0024] Figure 2 A schematic diagram of the 4×∞ tightly coupled array of the present invention is shown; wherein, (1) represents the wide-angle matching layer, which is a square structure with a side length W. 11 = 3.73 mm, patch spacing L 13 = 2.4 mm, patch distance from edge W 13 = 1.2 mm; (2) refers to a broadband high-efficiency electromagnetic structure, which is loaded with two trapezoidal openings, designed as trapezoid 1 and trapezoid 2 respectively. The long side W1 of trapezoid 1 is 36.8 mm, and the short side L is 1.2 mm. 15 = 1.8 mm, height H5 = 16.8 mm; the short side W of trapezoid 2 16 = 2 mm, longer side W 15 = 6 mm, height H4 = 10 mm. The introduced capacitance can be effectively controlled by adjusting the spacing and dimensions between the two inverted trapezoids. The long side L of the coupling metal patch... 14 = 8.8 mm, short side W 15 = 1.8 mm. Other parameters of the broadband high-efficiency electromagnetic structure include: W 19= 8.8 mm, W 20 = 3.2 mm, H6 = 13 mm, H7 = 4 mm, W 18 = 0.6 mm; (3) is a dielectric substrate connecting the wide-angle matching layer and the broadband high-efficiency electromagnetic structure, which is rectangular in shape, with a relative permittivity of 4.4, a relative permeability of 1, a loss tangent of 0.02, a lateral dimension of 36.8 mm × 36.8 mm, and a height H1 = 2 mm. The dielectric substrate is fixed to the feed structure by an embedded mounting method; (7) represents the dielectric substrate carrying the feed network, with a thickness of 0.762 mm and a height H3 = 25 mm; (6) is a microstrip line and integrated matching balun. Figure 3 Taking the front view as an example, the back of the microstrip line and integrated matching balun (6) is a metal ground plane, with the following dimensions: W5 = 2 mm, L1 = 2.77 mm, L2 = 20.27 mm, L3 = 4.54 mm, L5 = 25.24 mm, L6 = 2 mm, W2 = 0.5 mm, W3 = 2 mm, W4 = 0.6 mm. By adjusting the gradient dimensions of the microstrip line, the impedance matching performance can be further optimized; for details of the tightly coupled array unit feed structure, see Figure 4 Its specific parameters are: the width of the first impedance matching line is W8 = 0.73 mm, and its length is L. 10 = 9 mm; the second impedance matching line has a width W9 = 1.15 mm and a length L 11 = 9 mm; Length L of the third impedance matching line 12 = 1.5 mm, width W 10 = 1.6 mm. The impedance of the feed line increases step by step from top to bottom, which helps to reduce reflection during energy transmission and improve transmission efficiency; (10) is the metal ground plane of the antenna, with a length of W1=36.8mm and a width of W1=36.8mm. The function of the metal ground plane (10) is to suppress back radiation and improve antenna gain; (9) is the coaxial feed port of the antenna, which is used to inject excitation signal into the antenna.

[0025] Figure 9 and Figure 11 The active VSWR curves of the tightly coupled array under the semi-infinite condition are shown for both models. It can be seen that the active VSWR of the end unit of the tightly coupled array is significantly improved after loading with the broadband high-performance electromagnetic structure. When the active VSWR is less than 3, a frequency octave bandwidth of 5.21 (0.70-3.65GHz) is achieved, and the profile height of the array is only 0.061 low-frequency wavelengths, which effectively compensates for the problem of excessive capacitive reactance of the end unit caused by array truncation, thereby significantly improving impedance matching and suppressing edge effects.

[0026] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A tightly coupled array of an end-loaded broadband high-performance electromagnetic structure, comprising a radiating structure and a feeding structure, characterized in that: The radiation structure includes: a wide-angle matching layer (1) disposed on the top of the overall structure for extending the beam scanning range of the antenna; a broadband high-efficiency electromagnetic structure (2) as the core radiation and matching unit; a dielectric substrate (3) for supporting the wide-angle matching layer (1); a dielectric substrate (4) for fixing the broadband high-efficiency electromagnetic structure (2); and a metal short-circuit post (5) for optimizing impedance matching characteristics. The feed structure includes: a microstrip line and an integrated matching balun (6) for impedance transformation; a dielectric substrate (7) for carrying the feed network; a dielectric substrate (8) for fixing the microstrip line; a coaxial feed port (9) for signal input and output; and a metal ground plane (10) for suppressing back radiation and improving the forward gain of the antenna.

2. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The broadband high-efficiency electromagnetic structure (2) achieves mechanical connection and electromagnetic coupling through a dielectric substrate (3), and two trapezoidal openings are formed on the structure through a precision etching process (equivalent to introducing parallel capacitors in the radiator system to achieve better impedance matching). The wide-angle matching layer (1) is arranged on the upper surface of the dielectric substrate (3), while the broadband high-efficiency electromagnetic structure (2) is disposed on the lower surface of the dielectric substrate (3). The two are electromagnetically isolated by means of the dielectric substrate (3) and maintain a set distance, thereby significantly enhancing the radiation performance of the phased array in the wide-angle scanning state of the antenna.

3. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The linewidth of the gradient microstrip line (6) is continuously gradient along the signal transmission direction, thereby achieving smooth impedance transformation and wideband matching. The metal ground plane (10) is located below the gradient microstrip line, which plays the role of electromagnetic shielding and suppressing back radiation, which helps to improve the antenna gain. The coaxial feed port (9) is connected to the microstrip line and the integrated matching balun (6) to achieve efficient power transmission. At the same time, the metal ground plane (10) further optimizes the radiation pattern, suppresses unwanted radiation, and improves the overall antenna performance.

4. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The antenna element has an aperture size of 36.8mm × 36.8mm and an overall profile height controlled at 26mm, featuring low profile and easy integration.

5. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1 or 2, characterized in that: The dielectric substrate (3) used to connect the broadband high-efficiency electromagnetic structure and the wide-angle matching layer has a relative permittivity of 4.4, a relative permeability of 1, a loss tangent of 0.02, a planar external dimension of 36.8mm × 36.8mm, and a thickness of 1mm, and has excellent high-frequency signal transmission characteristics.

6. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1 or 2, characterized in that: The opening structure (2) etched on the butterfly radiator is in the shape of an inverted trapezoid. The first trapezoid has a height of 10 mm, a short side width of 2 mm, and a long side width of 6 mm. The second trapezoid has a height of 16.8 mm, a short side width of 1.8 mm, and a long side width of 36.8 mm. This design helps to optimize the current distribution and expand the impedance bandwidth.

7. The tightly coupled array of the end-loaded broadband high-performance electromagnetic structure according to claim 1 or 3, characterized in that: The gradient microstrip line (6) is a three-segment columnar structure with line widths of 1.6mm, 1.15mm and 0.73mm from top to bottom, and lengths of 1.5mm, 9mm and 9mm respectively. The metal ground line on the back is 2mm wide. This gradient structure effectively achieves continuous impedance transition and broadband matching.

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