Tight coupling array integrated with wave-absorbing feed network and manufactured by single-layer PCB (Printed Circuit Board)

Abstract

The invention belongs to the technical field of microwave antennas, and particularly provides a tightly-coupled array antenna which is integrated with a wave-absorbing feed network and is manufactured by a single-layer PCB (Printed Circuit Board), so as to solve the challenges of the existing antenna in the aspects of structural complexity, profile height and broadband matching. The antenna comprises a radiation unit, a wide-angle matching layer, a feed network integrated with a wave-absorbing resistor disc, a metal floor and a coaxial feed port. The core innovation of the antenna structure is that the wave-absorbing resistor disc is directly integrated in the feed network without adding an additional structural layer, and an additional resistor ring or resistive film is not needed. The structure has the advantages of high integration level, low profile, wide frequency band and the like, and meets the application requirements of modern communication and radar systems on high-performance phased-array antennas.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, and specifically relates to a tightly coupled array antenna manufactured on a single-layer PCB board with an integrated absorbing feed network. Specifically, it is an antenna design that absorbs electromagnetic waves of a specific frequency through a simple feed network structure. Background Technology

[0002] With the ever-increasing demands on antenna performance in modern communication and radar systems, compact, highly integrated, and high-efficiency antenna design has become a research hotspot. However, most existing antenna structures face some common problems: on the one hand, traditional array antennas typically employ multi-layer PCB designs, resulting in complex structures and cumbersome manufacturing processes, leading to increased costs and bulky size; on the other hand, effectively achieving impedance matching at different frequencies, especially at large angles of incidence, remains a technical challenge in wide-bandwidth, high-performance antenna design.

[0003] To improve antenna bandwidth, existing technologies often employ methods such as resistive loops and resistive films to absorb a portion of the waves radiated from the dipole towards the ground, preventing these waves from reflecting off the ground and superimposing on the main radiation to form a radiation null, thus limiting bandwidth. However, these solutions often require additional structural layers, increasing design complexity and manufacturing costs. Furthermore, traditional feed network designs are relatively complex and struggle to meet the demands of modern communication systems for high antenna integration, low profile, and simplified design.

[0004] Therefore, there is an urgent need for a new antenna design that can achieve better impedance matching and wider bandwidth on a single-layer PCB board, avoiding the complex structural design of traditional structures. Furthermore, the antenna design should also meet the demands of modern communication and radar systems for high integration, low profile, and low-cost manufacturing. Summary of the Invention

[0005] This invention aims to solve the impedance matching problem of tightly coupled array antennas in ultra-wideband and large scanning angle applications. It realizes a tightly coupled array antenna manufactured on a single-layer PCB board with integrated absorbing feed grid, which has the characteristics of high integration, low profile and wide bandwidth.

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

[0007] The antenna of the present invention consists of a frequency selective surface wide-angle matching layer, a radiating element layer, a feed network layer, and a metal ground plane.

[0008] The main body of the radiating element layer adopts a folded dipole antenna 3, which is placed parallel to the grounding metal plate 5. In order to effectively improve the impedance matching characteristics, snap-fit ​​coupling metal plates 4 are set on both sides above the dipole. By adjusting the geometric dimensions of the snap-fit ​​coupling metal plates 4, the coupling reactance value can be adjusted, thereby optimizing the high-frequency matching performance of the array and effectively improving the impedance mismatch phenomenon in the low-frequency band.

[0009] The power supply network is fed through a coaxial feed port 10 beneath the metal floor 9, and includes a dual Y-balun 6, a third-order Chebyshev impedance transformer 7, and absorbing resistors 8. The dual Y-balun converts the unbalanced input signal into a balanced signal. The third-order Chebyshev impedance transformer 7 ensures good impedance matching across the entire operating frequency band, optimizing wideband performance. The ends of the dual Y-balun 6 are connected to the dipole 3 via a tapered structure. To further improve bandwidth matching, two absorbing resistors 8 are introduced into the power supply network, which can effectively absorb electromagnetic waves of specific frequencies, reduce the influence of radiation nulls, extend the array bandwidth, and improve radiation efficiency.

[0010] The wide-angle matching layer of this invention is based on a frequency-selective surface wide-angle matching layer, implemented by printing composite patterned frequency-selective surface units on the upper and lower surfaces of a dielectric substrate 2. Each unit consists of six symmetrically arranged circular metal patches and two symmetrically arranged rectangular metal patches. By adjusting the geometric arrangement and size of the metal patches, the matching layer can achieve wide-band impedance matching, thereby effectively extending the antenna's operating bandwidth. This design not only improves the antenna's bandwidth performance but also ensures its stability and high performance during wide-angle scanning.

[0011] The innovation of this invention lies in:

[0012] I. This paper introduces two absorbing resistors at specific locations in the feed network, thereby enabling the feed network to absorb electromagnetic waves of specific frequencies. This effectively improves the impedance matching near the radiation null point and effectively extends the antenna's operating bandwidth.

[0013] Second, the use of a snap-fit ​​metal sheet structure enhances the coupling between adjacent units, which is beneficial to improving low-frequency matching. Ultimately, it can achieve a 13.7 octave bandwidth of 0.46-6.32 GHz and scanning of 60 degrees in the E plane and 45 degrees in the H plane when the active VSWR is less than 3.7, with a profile of only 0.086 times the wavelength. Attached Figure Description

[0014] Figure 1 This is an overall view of a tightly coupled array antenna manufactured on a single-layer PCB board with an integrated absorbing feed grid, as described in this invention.

[0015] Figure 2This is a front view of a tightly coupled array antenna manufactured on a single-layer PCB board with an integrated absorbing feed grid, as described in this invention.

[0016] Figure 3 This is a side view of a tightly coupled array antenna manufactured on a single-layer PCB board with an integrated absorbing feed grid, as described in this invention.

[0017] Figure 4 This invention describes the active standing wave (VSW) of a tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed mesh, under side-emitting, 60-degree E-plane scanning, and 45-degree H-plane scanning conditions.

[0018] Figure 5 This is the scanning pattern of the tightly coupled array on the E plane of a single-layer PCB board with an integrated absorbing feed grid as described in this invention.

[0019] Figure 6 This is the scanning pattern of a tightly coupled array in the H-plane of a single-layer PCB board with an integrated absorbing feed grid as described in this invention. Detailed Implementation

[0020] 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.

[0021] Figure 1 This is the overall structure of the invention. Figure 2 and Figure 3 These are the front and side views of the antenna of the present invention. The dielectric layer 2 is made of Rogers RO4350 material with a dielectric constant of 3.48 and a thickness of t1 = 0.762 mm. The length of the dielectric substrate is dE = 27.8 mm, and the height is H1 = 55.95 mm. It is set perpendicular to the metal ground plane 9. The frequency selective surface wide-angle matching layer 1 is composed of frequency selective surface units printed on the dielectric substrate 2 and its upper and lower surfaces, respectively. Each unit contains six symmetrically arranged circular metal pieces and two symmetrically arranged rectangular metal pieces. The diameter of the circular pieces is D1 = 3.9 mm, and the dimensions of the rectangular metal pieces are length L1 = 3.9 mm and width W1 = 3 mm, respectively.

[0022] The radiating unit layer includes a folded dipole 3 printed on the lower surface of the dielectric layer 2, with a width of W2 = 7 mm. On the upper surface of the dielectric layer 2, snap-fit ​​coupling metal sheets 4 are respectively disposed on both sides above the dipole. The snap-fit ​​coupling metal sheets 4 are composed of rectangular metal sheets with a length L2 = 9 mm and a width W3 = 4.6 mm. A row of metal through holes with a diameter D2 = 0.6 mm is disposed below the upper and lower edges of the rectangular metal sheets. Two grounding metal sheets 5 are disposed on both sides of the snap-fit ​​coupling metal sheets 4, with a width of W5 = 0.3 mm extending to the metal ground plane 9.

[0023] The feed network layer includes a dual Y-balun 6, a third-order Chebyshev impedance converter 7, an absorbing resistor 8, and a coaxial feed port 10. The microstrip line widths of the third-order Chebyshev impedance converter 7 are W6=1.34 mm, W7=1.1 mm, and W8=0.57 mm, respectively. The coaxial feed port 10 penetrates the metal ground plane 9, and the width of the 50-ohm input terminal, W9, is 1.6 mm, and it is electrically connected to the third-order Chebyshev impedance converter 7. The dual Y-balun 6 is printed on the front and back surfaces of the dielectric layer 2. The key parameters of the dual Y-balun 6 include the output terminal width W9=1.1 mm, the diameter of the metal via D3=0.6 mm, and the other two key parameters W9 and W10 are 2.6 mm and 3.2 mm, respectively.

[0024] The absorbing resistor 8 contains two surface-mount resistors connected in series with the double Y balun 6. Each resistor has a resistance of R = 100 Ω ± 5% and is used to absorb electromagnetic waves of a specific frequency.

[0025] The metal floor 9 is located at the bottom of the array and is electrically connected to the coaxial feed port 10. Through the coaxial feed port 10, the input signal is fed to the third-order Chebyshev impedance transformer 7. The third-order Chebyshev impedance transformer 7 matches the input 50-ohm impedance to the output 150-ohm impedance. The dual Y balun 6 converts the unbalanced signal into a balanced signal and then provides differential feeding to the folded dipole 3. The dipole 3 realizes the radiation of electromagnetic waves.

[0026] Figure 4 The active standing wave ratio (VSWR) of the tightly coupled phased array antenna described in this invention is demonstrated under the condition of infinite boundary, under side firing, 60-degree scanning in the E-plane, and 45-degree scanning in the H-plane. It can be seen that within the frequency band of 0.46-6.32 GHz, the active VSWR of this invention is less than 3.7, which meets the engineering requirements for the active VSWR of tightly coupled phased array antennas.

[0027] Figure 5 and Figure 6 The E-plane and H-plane scanning patterns of a tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid, as described in this invention, are shown. It can be seen that this invention achieves beam scanning of ±60° in the E-plane and ±45° in the H-plane with relatively low gain loss.

[0028] 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 manufactured on a single-layer PCB board with an integrated absorbing feed network, comprising a frequency-selective surface wide-angle matching layer (1), a dielectric substrate containing a printed antenna structure (2), a bowtie dipole (3), a snap-fit ​​coupling metal sheet (4), a grounding metal sheet (5), a double Y balun (6), a third-order Chebyshev impedance transformer (7), an absorbing resistor sheet (8), a metal ground plane (9), and a coaxial feed port (10), characterized in that, include: The frequency selection surface wide-angle matching layer (1), the radiating unit layer, the feed network layer and the metal floor (9) are stacked sequentially from top to bottom; The frequency selective surface wide-angle matching layer (1) is composed of a dielectric substrate (2) and frequency selective surface units with composite patterns printed on its front and back surfaces respectively. Each unit includes 6 symmetrical circular metal patches and two symmetrical rectangular metal patches. The dielectric substrate (2) is made of Rogers RO4350 material with a dielectric constant of 3.48 and a thickness of 0.762 mm, and is set perpendicular to the metal floor (9). The radiation unit layer is disposed below the frequency-selective surface impedance matching layer (1), specifically including a folded dipole (3) printed on the back of the dielectric layer (2), and snap-fit ​​coupling metal sheets (4) are provided on both sides in front of the folded dipole (3). The snap-fit ​​coupling metal sheet (4) is composed of a rectangular metal sheet and a row of metal through holes located behind its upper and lower edges to form a snap-fit ​​structure. Two grounding metal sheets (5) are respectively provided on both sides of the rectangular metal sheet. The grounding metal sheets (5) are electrically connected to the rectangular metal sheet and extend to the metal grounding plate (9). The feed network layer includes a dual Y-balun (6), a third-order Chebyshev impedance transformer (7), an absorbing resistor (8) integrated in the dual Y-balun (6), and a coaxial feed port (10). The absorbing resistor (8) consists of two surface-mount resistors with optimized resistance values, used to absorb electromagnetic waves in a specific frequency range, improve impedance matching and broadband characteristics at high frequencies, thereby improving the overall performance of the system. The absorbing resistor is directly connected in series in the dual Y-balun (6) to form the absorbing feed network section. The metal floor (9) is located at the bottom of the array, and the coaxial feed port (10) passes through the metal floor (9) and is electrically connected to the third-order Chebyshev impedance transformer (7).

2. The tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid according to claim 1, characterized in that: (1) Each unit contains 6 symmetrically arranged metal discs and two symmetrically arranged rectangular metal discs; the diameter of the unit discs is 3.65 mm, the length of the rectangular metal discs is 3.9 mm, and the width is 3 mm; the dielectric plate (2) has a relative permittivity of 3.48, a loss tangent of 0.004, and a thickness of 0.762 mm.

3. The tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid according to claim 1, characterized in that: The folded dipole (3) is printed on the back of the medium plate (2). The width of the dipole is 7 mm. On both sides directly above the folded dipole (3), there are snap-fit ​​coupling metal sheets (4). The snap-fit ​​coupling metal sheets (4) are made of rectangular metal sheets with a length of 9 mm and a width of 4.6 mm. Below the upper and lower edges of the rectangular metal sheets, there is a row of metal through holes with a diameter of 0.6 mm for each metal through hole. In addition, there are two grounding metal sheets on both sides of the rectangular metal sheets. The width of the metal sheets is 0.3 mm and they extend to the metal floor (9).

4. The tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid according to claim 1, characterized in that: The folded dipole (3) is connected to the double Y balun (6), and the double Y balun (6) is connected to the third-order Chebyshev impedance transformer (7); the microstrip line widths of the third-order Chebyshev impedance transformer (7) are 1.34 mm, 1.1 mm, and 0.57 mm respectively, and the coaxial feed port (10) is connected to the third-order Chebyshev impedance transformer (7); a metallized via is opened at the double Y balun (6), and the diameter of the metal via is 0.6 mm.

5. The tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid according to claim 1, characterized in that: The absorbing resistor (8) includes two chip resistors; the absorbing resistors are connected in series in the feed arm of the double Y balun (6), and their resistance is 100Ω±5% respectively. They are used to absorb electromagnetic waves of a certain frequency to improve impedance matching and broadband characteristics at high frequencies.

6. The tightly coupled array manufactured on a single-layer PCB board with an integrated absorbing feed grid according to claim 1, characterized in that: The tightly coupled array antenna unit manufactured on a single-layer PCB board with an integrated absorbing feed has a lateral dimension of 17mm × 0.762mm and a cross-sectional height of 55.95mm, which is only 0.097 times the low-frequency wavelength.

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