A tightly coupled phased array based on planar folded broadband high performance electromagnetic structure

Abstract

The present application belongs to the technical field of microwave antenna, and specifically provides a tight coupling phased array based on a planar folded broadband high-performance electromagnetic structure. The main structure of the present application comprises: a radiation structure (I), i.e. a rectangular metasurface structure loaded on the broadband high-performance electromagnetic structure, a metal support arm of a front metal dipole, and a metal support of a gradually changing structure of a rear metal dipole; a feed structure (II), i.e. a gradually changing microstrip feed line, a balun structure and a coaxial line. The present application designs a one-dimensional linear array by replacing the dipole of the edge unit in the traditional tight coupling array with the broadband high-performance electromagnetic structure. Loading the broadband high-performance electromagnetic structure on the edge unit of the tight coupling array can suppress the edge truncation effect. By using a meandered and folded microstrip line to connect the broadband high-performance electromagnetic structure, the surface current is increased, thereby introducing additional capacitance to improve the matching effect of the edge unit of the array, so as to achieve the purpose of suppressing the edge truncation effect of the array.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically providing a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure. Background Technology

[0002] To meet the demands of modern radar and communication systems, broadband phased arrays with wide-angle scanning capabilities have become a research hotspot. The unique advantages of these phased arrays in rapid electronic scanning and dynamic beamforming make them promising for applications in electronic warfare, radar detection, and high-speed communication. With the continuous development of phased array technology, achieving low-profile antenna structures and ultra-wideband operating frequencies has become a core challenge. Traditional broadband phased array antennas, such as the gradient slot arrays widely used in ultra-wideband systems, while offering wide bandwidths, have large profile heights, making them difficult to meet current application requirements.

[0003] Achieving ultra-wideband characteristics in array antennas with weak inter-element coupling presents several limitations. The highest operating frequency of the array antenna is constrained by the conditions for grating lobe formation; that is, the element spacing typically cannot exceed half the wavelength of the highest operating frequency. Furthermore, the lowest operating frequency is limited by the electrical dimensions of the elements; if the element size is too small, the low-frequency radiation efficiency will significantly decrease. However, by effectively utilizing the strong electromagnetic coupling between elements, the equivalent electrical dimensions of the array can be extended, allowing it to maintain good impedance matching and radiation characteristics in the low-frequency band, thereby significantly widening the operating bandwidth.

[0004] The theoretical framework for planar phased arrays was initially proposed by Wheeler, whose infinite current sheet model provided a crucial foundation for subsequent research. Traditional array designs typically select independent broadband antennas as radiating elements and suppress mutual coupling through optimized layout to maintain the stability of the element pattern and impedance. However, this method has limitations in extending bandwidth. Munk took a different approach, proposing a design strategy to extend bandwidth by introducing inter-element coupling. For example, introducing capacitive connection structures at the ends of dipole arms enhances the coupling between collinearly arranged elements. Combined with the inductive characteristics of the dipole itself, this effectively compensates for impedance mismatch caused by the ground plane, thereby achieving ultra-wideband and wide-angle scanning while maintaining a low-profile structure. Furthermore, loading a dielectric layer onto the antenna radiating aperture can further improve impedance bandwidth and beam scanning range. Summary of the Invention

[0005] The goal of this invention is to fill the gap in the field of tightly coupled phased array antenna technology and provide a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure.

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

[0007] The structure of this invention mainly consists of two parts: a radiating structure and a feeding structure. The radiating part mainly comprises a broadband high-performance electromagnetic structure and a wide-angle matching layer. The broadband high-performance electromagnetic structure is based on a tightly coupled array design, utilizing the strong electromagnetic coupling effect between elements to extend the antenna's operating bandwidth. The wide-angle matching layer is located on the upper surface of the dielectric substrate, and the broadband high-performance electromagnetic structure is arranged on the lower surface of the dielectric substrate. The two are isolated by the dielectric substrate and maintain a certain distance. The introduction of this wide-angle matching layer effectively enhances the impedance matching performance during large-angle scanning.

[0008] The power supply 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 power supply port to the radiating element, helping to overcome mismatch issues in broadband matching. A metal ground plane is positioned below the tapered microstrip line, providing electromagnetic shielding and back-radiation suppression, while also effectively absorbing reflected energy, improving inter-element isolation, and enhancing overall radiation performance.

[0009] The innovation of this invention lies in:

[0010] I. Replacing the traditional dipole units of the array edge units with broadband high-performance electromagnetic structures can improve the impedance mismatch problem caused by the edge truncation effect in tightly coupled arrays, optimize impedance matching, and broaden the impedance bandwidth of the array.

[0011] Second, using microstrip lines to connect the edges of broadband high-performance electromagnetic structures can enhance the surface current of the broadband high-performance electromagnetic structures, introduce additional capacitance in the array, and further optimize the impedance matching effect of the array. Attached Figure Description

[0012] Figure 1 is an overall view of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0013] Figure 2 This is a partial structural schematic diagram of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0014] Figure 3 This is a schematic diagram of a unit wide-angle matching layer of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0015] Figure 4 This is a schematic diagram of the edge unit broadband high-performance electromagnetic structure of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure, as disclosed in an embodiment of the present invention.

[0016] Figure 5 This is a schematic diagram of the central unit dipole structure of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention.

[0017] Figure 6 This is a schematic diagram of a unit feed structure for a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure, as disclosed in an embodiment of the present invention.

[0018] Figure 7 is a schematic diagram of the back metal layer of the feeding structure of a conventional tightly coupled phased array disclosed in an embodiment of the present invention.

[0019] Figure 8 This is a front view of an array cell structure of a tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure disclosed in an embodiment of the present invention;

[0020] Figure 9 This is a diagram of a tightly coupled array model where the end units are conventional dipoles, as disclosed in an embodiment of the present invention.

[0021] Figure 10 The active standing wave curve of a tightly coupled array when the end unit is a conventional dipole, as disclosed in the embodiments of the present invention;

[0022] Figure 11 The active standing wave curve of the tightly coupled 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] (1) is a wide-angle matching layer, which consists of periodically arranged rectangular patches with length and width W1=3.73mm and L1=3.73mm respectively. The spacing between different rectangles is W2=2.4mm and L2=2.4mm respectively; (2) is a broadband high-performance electromagnetic structure with two open structures loaded on it. The loaded broadband high-performance electromagnetic structure (2) is designed in two trapezoids. The long side W3=36.8mm, the short side W8=3.2mm, and the height is 17mm for trapezoid 1. The short side W6=2mm, the long side W7=10mm, and the height is 8mm for trapezoid 2. The size of the introduced capacitor can be controlled by controlling the spacing between the two inverted trapezoids and the size of the inverted trapezoids. The parameters of the microstrip lines loaded on the broadband high-performance electromagnetic structure are W4=5.37mm, W5=3.34mm, L3=2.5mm, L4=7.5mm, and L5=12mm, respectively; (3) is a dielectric substrate connecting the wide-angle matching layer (1) and the broadband high-performance electromagnetic structure (2). The dielectric substrate (3) has a relative permittivity of 2.2, a relative permeability of 1, and a loss tangent of 0.0009. Its length, width, and height are 36.8mm, 36.8mm, and 2mm, respectively. The dielectric substrate (3) fixes the feed structure by embedding; the dielectric substrate (4) is located below the broadband high-performance electromagnetic structure. Its relative permittivity is 4.4, its relative permeability is 1, and its loss tangent is 0.02. Its length, width, and height are 36.8mm, 36.8mm, and 1mm, respectively; the metal patch (5) is used to enhance the coupling between units. The length and width of the metal patch at the edge of the array are 6mm and 1.5mm, respectively. The metal patch of the array's center unit has a length of 8.8 mm and a width of 1.8 mm. Changing the length of the metal patches in the array's edge units can also optimize the array's impedance matching. The structural parameters of the center unit dipole are L7 = 4 mm, W9 = 8.8 mm, W... 10 =1.8mm; (6) is the microstrip matching circuit and balun. By adjusting the length and width of the microstrip line, the impedance matching characteristics of the array can be optimized. Its structural parameters are L8=2.6mm, L9=2mm, L 10 =9mm, L 11 =9mm, L 12 =1.5mm, L 13 =2mm, W 11 =0.44mm, W 12 =0.73mm, W 13 =1.15mm, W 14 =1.6mm, W 15=2mm; (7) is the dielectric substrate supporting the microstrip matching circuit and the balun (6). The dielectric substrate (7) has a relative permittivity of 3.66, a relative permeability of 1, and a loss tangent of 0.004. Its length, width, and height are 36.8mm, 25mm, and 0.762mm, respectively; (8) is the metal layer on the back of the microstrip matching circuit and the balun (6), which can suppress the radiation of the feed network to other directions. Its structural parameters are W 16 =2mm, W 17 =2.8mm, W 18 =2mm, L 14 =4.54mm, L 15 =20.27mm; (9) is the antenna feed port, used to feed energy into the phased array. (10) is the metal ground plane, which suppresses the array from radiating to the back, thereby improving the antenna gain. Figure 8 The image shows a front view of a tightly coupled array unit. The relevant structural parameters are W3=36.8mm, H1=2mm, H2=1mm, and H3=25mm.

[0025] Figure 9 This is a diagram of a tightly coupled array model where the end units are traditional dipoles. Figure 10 and Figure 11 The figures show the active standing wave (VSWR) curves of the tightly coupled array with and without a broadband high-performance electromagnetic structure at the end. When the active VSWR is less than 3, a frequency octave bandwidth of 4.96 (0.78-3.87 GHz) is achieved, and the array's profile height is only 0.0681 low-frequency wavelengths. Compared with the active VSWR curves of traditional tightly coupled phased arrays, it can be seen that the tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure proposed in this invention can significantly broaden the impedance bandwidth of the tightly coupled phased array, improve the active VSWR of the edge elements of the tightly coupled array, and effectively suppress the edge truncation effect.

[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 phased array based on a planar folded broadband high-performance electromagnetic structure, comprising a radiating structure and a feeding structure, characterized in that: The radiating portion includes: a wide-angle matching layer (1) disposed on the top layer for extending the antenna scanning range; a broadband high-performance electromagnetic structure (2); a dielectric substrate (3) supporting the wide-angle matching layer (1); a dielectric substrate (4) supporting the broadband high-performance electromagnetic structure (2); and a rectangular patch (5) for enhancing the coupling between dipoles. The power supply section includes: a microstrip matching circuit and a balun (6) for impedance transformation; a dielectric substrate (7) supporting the power supply network; a metal layer (8) for suppressing back radiation of the power supply network; a power supply port (9); and a metal ground plane (10) for suppressing back radiation.

2. The tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The broadband high-performance electromagnetic structure (2) is connected through a dielectric substrate (3). Two trapezoidal opening structures are formed on the structure (2) by etching. The wide-angle matching layer (1) is disposed on the upper surface of the dielectric substrate (3). The broadband high-performance electromagnetic structure (2) is disposed on the upper surface of the dielectric substrate (4). The wide-angle matching layer (1) and the broadband high-performance electromagnetic structure (2) are isolated from each other through the dielectric substrate (3) and maintain a predetermined distance, thereby improving the matching effect of the phased array. The rectangular patch (5) is placed below the adjacent dipoles to strengthen the coupling between the dipoles.

3. The tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The microstrip matching circuit and balun (6) adopt a trace structure with gradually changing linewidth, which can realize continuous impedance transformation and thus achieve broadband matching; the metal layer (8) supporting the feed network is arranged behind the dielectric substrate (7) to absorb reflected energy and improve port isolation; the feed port (9) is connected to the microstrip matching circuit and balun (6) to realize signal feeding; the metal ground plane (10) is located below the microstrip line, which plays the role of electromagnetic shielding and suppressing back radiation, and helps to improve antenna gain.

4. The tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1, characterized in that: The phased array antenna element has a lateral dimension of 36.8mm × 36.8mm and a cross-sectional height of 26mm.

5. A tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1 or 2, characterized in that: The dielectric substrate (3) connecting the broadband high-performance electromagnetic structure (2) and the wide-angle matching layer (1) has a relative permittivity of 2.2, a relative permeability of 1, a loss tangent of 0.0009, a lateral dimension of 36.8mm × 36.8mm, and a height of 1mm.

6. A tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1 or 2, characterized in that: The broadband high-performance electromagnetic structure (2) is composed of two trapezoids. The height of trapezoid 1 is 17mm, the short side is 3.2mm, and the long side is 36.8mm. The height of trapezoid 2 is 10mm, the short side is 2mm, and the long side is 6mm. The structural parameter error of the broadband high-performance electromagnetic structure (2) can be matched within 1mm. However, such parameter settings make the matching effect of the phased array the best. The edges of the trapezoidal structure are connected by microstrip lines, which can enhance the surface current of the broadband high-performance electromagnetic structure.

7. A tightly coupled phased array based on a planar folded broadband high-performance electromagnetic structure according to claim 1 or 3, characterized in that: The width-gradient microstrip matching circuit and balun (6) have microstrip line widths of 1.6mm, 1.15mm and 0.73mm from bottom to top, and microstrip line lengths of 1.5mm, 9mm and 9mm from bottom to top. The width of the metal on its back is 2mm.

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