High-performance tight-coupling phased-array antenna applying frequency-variable impedance matching layer

Abstract

The invention belongs to the technical field of microwave antennas, and particularly provides a tight coupling phased-array antenna based on an application frequency-variable impedance matching layer, so as to solve the challenges of the existing phased-array antenna in the aspects of dynamic adjustability and environmental adaptability. The three-order Chebyshev impedance converter comprises a reconfigurable surface loaded with a diode, a bow-tie type dipole, a double-Y balun, a three-order Chebyshev impedance converter, a coaxial feed port, a metal floor, a dielectric layer, a grounding metal sheet and a metal chip resistor. The three-order Chebyshev impedance transformer, the chip resistor and the double-Y balun are cascaded to carry out broadband balanced feed on the dipole, and the dielectric constant and the magnetic conductivity of the dielectric substrate are changed through the on-off of the diode, so that the impedance matching and radiation characteristics of the phased-array antenna are improved. According to the invention, dynamic requirements of modern communication and radar systems on antenna performance can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and particularly relates to a high-performance tightly coupled array applying a frequency-variable impedance matching layer, and more particularly to a wide-angle impedance matching structure based on the collaborative design of periodic metal units and tunable elements. Background Art

[0002] With the accelerating evolution of wireless communication systems towards high frequency, wide bandwidth and multi-scenario directions, more stringent requirements are imposed on the performance of antenna systems in fields such as modern mobile communication, satellite Internet and radar detection. The working bandwidth requirement for antennas in modern wireless systems has shifted from traditional narrowband and multi-frequency independent coverage to ultra-wideband (UWB) continuous coverage.

[0003] The tightly coupled array (TCA) utilizes the strong mutual coupling effect of elements to break through the aperture limit and can theoretically achieve ultra-wideband operation with a ratio of more than 10:1. However, its wide-angle scanning performance is limited by the static response characteristics of the fixed matching layer, and it is difficult to maintain stable impedance matching characteristics within an ultra-wide frequency band and a large angle of incidence range.

[0004] In recent years, the frequency-variable impedance matching layer has provided a new idea for dynamic impedance matching. By embedding adjustable elements such as PIN diodes or varactor diodes, this technology can adjust the equivalent permittivity and permeability distributions of the wide-angle matching layer in real time, and dynamically compensate for the array impedance mismatch caused by wide-angle scanning. The existing adjustable matching layers have insufficient dynamic impedance compensation accuracy under wide-angle scanning and are difficult to achieve stable regulation of wide-angle beams with low profile and low loss, which has become the core bottleneck restricting the engineering application of high-performance tightly coupled arrays. Therefore, there is an urgent need for a high-performance tightly coupled array applying a frequency-variable impedance matching layer. Summary of the Invention

[0005] The present invention aims to solve the impedance mismatch problem of tightly coupled arrays in ultra-wideband and wide-angle scanning scenarios, and to realize an ultra-wideband and large scanning angle tightly coupled phased array antenna applying a frequency-variable impedance matching layer.

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

[0007] The present invention mainly consists of a frequency-variable impedance matching layer, a radiation element layer, a feeding network layer and a metal floor.

[0008] The main body of the radiation element layer adopts a symmetric trapezoidal structure dipole antenna 4, which is placed parallel to the grounded metal sheet 9. In order to effectively compensate for the inductive impedance generated by the grounded metal sheet 9 in the low-frequency band, two metal sheets 5 are printed on both sides below the dipole. By adjusting the geometric dimensions (length and width) of the metal sheets, the coupling capacitance value can be precisely adjusted, thereby significantly improving the low-frequency response characteristics of the system and realizing the downward expansion of the working bandwidth.

[0009] The feeding network is fed through the coaxial cable 13 under the floor via the floor 12, and includes a dual-Y balun 7, a third-order Chebyshev impedance transformer 8, and a patch resistor 11. The dual-Y balun is used to convert the unbalanced signal into a balanced signal. The impedance transformer adopts a third-order Chebyshev impedance transformer for ultra-wideband impedance transformation. To ensure good bandwidth matching, the patch resistor 11 is introduced. To optimize the intermediate-frequency impedance matching, the end of the dual-Y balun is gradually connected to the dipole.

[0010] To simultaneously improve the profile, bandwidth, and scanning ability of the array, a frequency-variable impedance matching layer is adopted. This wide-angle matching layer is composed of periodically arranged metal sheets and PIN diodes (2). By using the on-off state of the PIN diodes (2), the equivalent permittivity and permeability distribution of the wide-angle matching layer can be adjusted in real time. Specifically, by dynamically controlling the on-off state of the matching layer diodes, the equivalent characteristic impedance of the matching layer can be changed, so as to expand the low-frequency bandwidth without affecting the high-frequency cut-off frequency, and finally realize the simultaneous improvement of the profile, bandwidth, and scanning ability.

[0011] The innovation of the present invention lies in:

[0012] First, this paper uses a frequency-variable impedance matching layer to replace the traditional non-frequency-variable impedance matching layer, so as to realize the simultaneous improvement of the profile, bandwidth, and scanning ability.

[0013] Second, by loading the frequency-variable impedance matching layer and using the on-off state of the PIN diodes, it is equivalent to sampling the characteristic impedance curve of the frequency-variable impedance matching layer twice. Finally, a six-fold frequency bandwidth of 0.77 - 4.6 GHz with an active voltage standing wave ratio less than 3 and a scan of 70 degrees in the E-plane and 60 degrees in the H-plane can be realized, and the profile is only 0.082 times the wavelength. Brief Description of the Drawings

[0014] Figure 1 is the overall view of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention;

[0015] Figure 2 is the top view of the frequency-variable impedance matching layer of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention;

[0016] Figure 3 is the top view of the bow-tie dipole layer of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention;

[0017] Figure 4 is the overall side view of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention;

[0018] Figure 5is the active standing wave of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned on, with side radiation, 70-degree E-plane scanning, and 60-degree H-plane scanning;

[0019] Figure 6 is the active standing wave of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned off, with side radiation, 70-degree E-plane scanning, and 60-degree H-plane scanning;

[0020] Figure 7 is the E-plane scanning pattern of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned on;

[0021] Figure 8 is the H-plane scanning pattern of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned on;

[0022] Figure 9 is the E-plane scanning pattern of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned off;

[0023] Figure 10 is the H-plane scanning pattern of the high-performance tightly coupled array applying the frequency-variable impedance matching layer when the PIN diode is turned off; Specific implementation

[0024] To make the objectives, technical solutions, and innovative points of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0025] Figure 1 is the overall structure of the present invention, Figure 2 and Figure 3 are respectively the top views of the wide-angle matching layer and the dipole layer of the present invention. Among them, the dielectric layer 3 uses F4B material, with a dielectric constant of 2.2, a thickness H4 of 4 mm, and both the length and width being dE = 27.8 mm; periodic metal plates are printed on the uppermost part of the dielectric plate 3 to implement the frequency-variable impedance matching layer 1. The length L1 of the unit metal sheet is 12.9 mm, and the width W1 is 4.7 mm. There is an air layer with a height H3 = 2 mm between the dielectric layer 3 and the dielectric layer 6. Both the dielectric layer 6 and the dielectric layer 10 use Rogers RO4350 material, with a dielectric constant of 3.66. The height H2 of the dielectric layer 6 is 1 mm, and the height H1 of the dielectric layer 10 is 25 mm; bow-tie dipoles 4 are printed above the dielectric plate 6. The length of one side of the dipole is L2 = 13 mm, and the end width W2 is 7.3 mm; a coupling metal sheet structure 5 is printed below the dielectric layer 6. The length and width of the metal sheet 5 are 8 mm and 2.6 mm respectively.

[0026] The feeding network is composed of a double-Y balun 7, a third-order Chebyshev impedance transformer 8, a patch resistor 11, and a coaxial feeding port 13.

[0027] The double-Y balun 7, the third-order Chebyshev impedance transformer 8, and the patch resistor 11 are printed on the dielectric board 10. The width W4 of the output end of the double-Y balun 7 is 1.1 mm, and the other two key parameters W9 and W 10 are 2.6 mm and 3.2 mm respectively; the third-order Chebyshev impedance transformer 8 is divided into three sections. The widths W5, W6, and W7 of the three sections from the signal output end to the signal input end are 0.67 mm, 0.9 mm, and 1.35 mm respectively, and the width W8 of the 50-ohm input end is 1.6 mm; the grounding metal sheets 9 are printed on both sides of the dielectric board 10, and its width W 11 is 0.5 mm. The floor 12 is loaded under the dielectric board 10. The energy of the antenna is fed in through the coaxial port 13 passing through the floor. The third-order Chebyshev impedance transformer 8 matches the input 50-ohm impedance to the output 150-ohm impedance. The patch resistor 11 is printed between the third-order Chebyshev impedance transformers 8 to ensure impedance continuity. Then, the double-Y balun 7 converts the unbalanced signal into a balanced signal and gives differential feeding to the bow-tie dipole 4, and the dipole 4 realizes the radiation of electromagnetic waves.

[0028] Figure 4 Shows the active standing waves of the side radiation, E-plane 70-degree scan, and H-plane 60-degree scan of the tightly coupled phased array antenna under the infinite boundary condition. It can be seen that within the frequency band of 0.5 GHz - 3 GHz, the active standing wave of the present invention is less than 4, meeting the requirements of the project for the active standing wave of the tightly coupled phased array antenna.

[0029] Figure 5 Shows the active standing waves of the side radiation, E-plane 70-degree scan, and H-plane 60-degree scan of the tightly coupled phased array antenna when the PIN diode is turned on under the infinite boundary condition. It can be seen that when the diode is turned on, within the frequency band of 0.77 GHz - 2.65 GHz, the active standing wave of the present invention is less than 3, meeting the requirements of the project for the active standing wave of the tightly coupled phased array antenna; Figure 6 Shows the active standing waves of the side radiation, E-plane 70-degree scan, and H-plane 60-degree scan of the tightly coupled phased array antenna when the PIN diode is turned off under the infinite boundary condition. It can be seen that when the diode is turned off, within the frequency band of 2.53 GHz - 4.6 GHz, the active standing wave of the present invention is less than 3, meeting the requirements of the project for the active standing wave of the tightly coupled phased array antenna.

[0030] Figure 6 Shows the radiation pattern of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention during the E-plane ±70-degree beam scan;

[0031] Figure 7And Figure 8 respectively show the E-plane and H-plane scanning patterns of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention when the PIN diode is turned on;

[0032] Figure 9 And Figure 10 respectively show the E-plane and H-plane scanning patterns of the high-performance tightly coupled array applying the frequency-variable impedance matching layer of the present invention when the PIN diode is turned off. It can be seen that the present invention realizes beam scanning of ±70 degrees in the E-plane and ±60° in the H-plane with a low gain loss.

[0033] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A high-performance tightly coupled array applying a frequency-variable impedance matching layer, comprising a frequency-variable impedance matching layer (1), PIN diodes (2), a dielectric board (3) for printing the frequency-variable impedance matching layer structure, bow-tie dipoles (4), metal sheets (5) introducing capacitive coupling, a dielectric board (6) for printing the antenna radiation structure, a dual-Y balun (7), a third-order Chebyshev impedance transformer (8), a grounding metal sheet (9), a dielectric board (10) for printing the balun and feeding structure, patch resistors (11), a metal floor (12), and a coaxial feeding port (13), characterized in that, Including: A frequency-variable impedance matching layer (1), a radiation element layer, a feeding network layer, and a metal floor (12) stacked layer by layer from top to bottom; The frequency-variable impedance matching layer (1) is composed of a dielectric plate (3) and adjustable units periodically arranged on its upper surface. Each adjustable unit includes six PIN diodes (2) and metal sheets. The PIN diodes (2) are connected between the metal sheets in a symmetric topology, and by controlling the on-off state, the equivalent permittivity and permeability distribution of the matching layer are dynamically adjusted. The dielectric plate (3) is made of F4B modified polytetrafluoroethylene composite material with a permittivity of 2.2; The radiation element layer includes a dielectric layer (6) and a bow-tie dipole (4) etched on its front surface. Metal sheets (5) for introducing coupling are arranged on both sides below the bow-tie dipole (4). The dielectric layer (6) is made of Rogers RO4350 with a thickness of 1 mm; The feeding network layer includes a double-Y balun (7), a third-order Chebyshev impedance transformer (8), a patch resistor (11), and a coaxial feeding port (13). The third-order Chebyshev impedance transformer (8) and the double-Y balun (7) are printed on the front and back surfaces of the dielectric layer (10) respectively. The dielectric layer (10) is made of Rogers RO4350 and is arranged perpendicular to the metal floor (12). The patch resistor (11) is connected in series in the third-order Chebyshev impedance transformer (8). The metal floor (12) is located at the bottom of the array, and a grounding metal sheet (9) is arranged on its surface. The grounding metal sheet (9) is located on both sides of the dielectric layer (10) and extends to the metal floor (12); The coaxial feeding port (13) penetrates the metal floor (12) and is electrically connected to the third-order Chebyshev impedance transformer (8).

2. The high-performance tightly coupled array applying a frequency-variable impedance matching layer according to claim 1, wherein: Each unit of the frequency-variable impedance matching layer (1) contains six PIN diodes (2) and periodically arranged metal sheets. The PIN diodes (2) are connected between the unit metal sheets in a symmetric topology. The unit metal sheet has a length of 12.9 mm and a width of 4.7 mm. The relative permittivity of the dielectric plate (3) is 2.2, the loss tangent is 0.001, the lateral dimension is 27.8 mm×27.8 mm, and the height is 4 mm.

3. The high-performance tightly-coupled array applying a frequency-variable impedance matching layer according to claim 1, wherein: The metal sheets (5) for introducing capacitive coupling are printed on both sides of the bow-tie dipole (4), with a length of 8 mm and a width of 2.6 mm.

4. The high-performance tightly coupled array applying a frequency-variable impedance matching layer according to claim 1, wherein The bow-tie dipole (4) is a symmetric trapezoidal structure and is connected to the double-Y balun (7). The double-Y balun (7) is connected to the third-order Chebyshev impedance transformer (8). The microstrip line widths of the third-order Chebyshev impedance transformer (8) are 1.35 mm, 0.9 mm, and 0.67 mm in sequence. The coaxial feeding port (13) is connected to the third-order Chebyshev impedance transformer. Metal vias are opened at the double-Y balun (7), and the diameter of the metal vias is 0.4 mm.

5. The high-performance tightly coupled array applying a frequency-variable impedance matching layer according to claim 1, wherein: The patch resistor (11) between the feeding lines has a resistance value of 100 Ω±5% and is used to adjust the impedance continuity of the feeding lines.

6. The high-performance tightly-coupled array applying a frequency-variable impedance matching layer according to claim 1, wherein: The high-performance tightly coupled array antenna unit with an application of a frequency-variable impedance matching layer has a lateral size of 27.8 mm × 27.8 mm and a profile height of 32 mm, and its profile height is only 0.082 times the wavelength.

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