Low-profile ultra-wideband metallic tightly coupled phased array antenna

Abstract

The present invention belongs to the technical field of microwave antennas, and specifically provides a low-profile ultra-wideband metal tightly coupled phased array antenna to achieve the ultra-wideband working bandwidth and the high power resistance characteristics of tightly coupled phased array antennas. The present invention includes: a radiation structure, namely two mutually crossed metal dipoles, an open structure loaded on the metal dipole, a dielectric pillar connecting the two dipoles, and a metal support with a gradient structure below the metal dipole; a feeding structure, namely a gradient metal feeding strip, a metal block with an open slot, a floor, and a coaxial line. The present invention suppresses out-of-band interference by realizing a filter structure by slotting in the metal, realizes the feeding of the dipole by a gradient metal feeding structure, and reduces the input impedance by introducing two parallel capacitors by etching slots on the metal dipole, thereby achieving better impedance matching and expanding the working bandwidth of the antenna. The invention can be used in electronic countermeasure systems and high-speed aircraft.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and specifically provides a low-profile ultra-wideband metal tightly coupled phased array antenna. Background Art

[0002] In wireless communication and radar systems, in order to improve the information transmission rate, extend the communication distance and increase the airspace coverage, phased array technology with ultra-wide bandwidth angle scanning is usually used. The traditional ultra-wideband phased array design usually designs units with broadband performance first, and then forms an array. However, this method will increase the coupling between units due to the increase in the number of antenna units, which will have a negative impact on the broadband performance of the antenna unit. In order to suppress the mutual coupling effect between units, it is possible to increase the unit spacing, but this will cause grating lobes to appear in the radiation pattern and increase the array volume. Although loading special structures between array elements can suppress mutual coupling, this will complicate the phased array structure.

[0003] In order to solve the above problems, scholars have extensively studied the tightly coupled phased array antenna technology based on the Wheeler infinite current sheet. The tightly coupled phased array antenna adopts an array-based design method, which uses a limited number of array elements to approximate the radiation efficiency of the infinite current sheet, and breaks through the limitation of the array element spacing by enhancing the mutual coupling effect between units, thereby achieving wide scanning angle, broadband and low profile performance at the same time.

[0004] At present, the radiating metal sheets of tightly coupled phased array antennas are usually printed on dielectric substrates, but there is a lack of research on low-profile metal tightly coupled phased array antennas. Compared with dielectric printed antennas, metal antennas have the advantages of high power resistance and stronger mechanical stability, which makes them have greater application advantages in certain special fields, such as electronic countermeasure systems and high-speed aircraft. Therefore, it is of great significance to study low-profile ultra-wideband metal tightly coupled phased array antennas. Summary of the invention

[0005] The objective of the present invention is to make up for the lack of low-profile ultra-wideband metal tightly coupled phased array antenna technology and to realize a metal tightly coupled phased array antenna that can achieve broadband, wide scanning angle and low profile.

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

[0007] The present invention is mainly composed of a radiation structure and a feeding structure. The radiation structure is in the form of two mutually crossed metal dipole antennas, and an opening structure is loaded on the dipole. The opening structure can introduce two parallel capacitors for the antenna, thereby improving the impedance matching of the antenna within the working frequency band. The two crossed dipoles are connected by a dielectric column, and the introduction of the dielectric column can broaden the working bandwidth of the antenna. The metal support with a gradient structure connected below the dipole can improve the stability of the overall antenna while minimizing the impact on the antenna radiation performance.

[0008] Since the radiation impedance of the dipole antenna is relatively high, it is extremely challenging to achieve broadband impedance transformation in a metal structure, which is a major difficulty of the present invention. In order to solve this problem, the present invention uses a gradient metal feed strip to meet the impedance change. This structure gradually narrows from the bottom to the top, and can meet the impedance transformation of about 50 ohms to 150 ohms; the metal feed strip is connected to the coaxial line through a metal block with an open slot, and the metal block with an open slot forms a filter structure by designing the shape of the open slot on it, which can effectively suppress clutter coupling and resonant interference, expand the antenna bandwidth and eliminate in-band resonance; the outer conductor of the coaxial line is connected to the floor, and the inner conductor passes through the floor and is directly connected to the metal block with an open slot.

[0009] The innovation of the present invention lies in:

[0010] First, two parallel capacitors are introduced by loading an opening structure on two intersecting dipoles, thereby balancing the real and imaginary impedance parts of the dipole antenna, reducing the imaginary impedance part of the dipole antenna, and realizing the characteristics of ultra-wideband and wide scanning angle of the antenna.

[0011] Second, by adding a gradient metal feed strip and a metal block with an open slot, the metal dipole is fed with filtering performance, which not only solves the difficulty of impedance matching of the dipole antenna in the design of the metal tightly coupled phased array antenna, but also suppresses the out-of-band gain and eliminates the out-of-band clutter signal, achieving better impedance conversion and effectively reducing the cross-sectional height of the antenna. Specific implementation plan

[0012] In order to make the objectives, technical solutions and innovative points of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0013] Figure 1 This is the overall structure of the present invention, which includes a radiation structure I and a feeding structure II from top to bottom.

[0014] Figure 2 The feeding structure and the radiation structure of the present invention are shown. Figure 3 is its front view, Figure 4 is its side view, Figure 5This is its top view. Figure 6 This is its bottom view. 1 is two metal dipoles that cross each other, and the length of the metal dipole is L 7 =56.6mm, height h 1 =35mm, W 3 = 2mm; 2 is the opening structure loaded on the two intersecting metal dipoles 1, the loaded opening structure 2 is designed as two inverted trapezoids, and the distance between the two inverted trapezoids is h 6 =7mm, a through hole length L is left between the two inverted trapezoids 1 =2mm, the short side L of the downward inverted trapezoid 5 =7.4mm, long side L 4 =13mm, height h 9 =7mm, the short side L of the upper inverted trapezoid 3 =18.6mm, long side L 2 =24.2mm, height h 5 =7mm, the size of the introduced capacitance can be controlled by controlling the distance between the two inverted trapezoids and the size of the inverted trapezoids; 3 is a dielectric support connecting the two dipoles, the dielectric support 3 is cylindrical, the relative dielectric constant of the dielectric support 3 is 2.2, the relative magnetic permeability is 1, the loss tangent is 0.0009, the diameter R1=8mm, the height h 2 =75mm, the dielectric support 3 is fixed and connected by embedding the two intersecting metal dipoles 1; 4 is the metal support of the gradient structure below the metal dipole, and the thickness of the metal support 4 of the gradient structure is W 1 =2mm, maximum length L 6 =31mm; 5 is a gradient metal feeder belt, the length of the gradient metal feeder belt 5 is L 8 =2mm, lower length L 9 =5mm, height h 4 =20mm, thickness W 2 =2mm, the length of the feeding strip decreases from bottom to top, so that there is less reflected energy during the transmission process. At the same time, the upper and lower lengths of the slot can be adjusted to change the impedance change; 6 is a metal block with an open slot, and the length of the entire metal block is L 5 =16.7mm, height h 3 =18.6mm, thickness W 2 =2mm, the internal opening groove structure can be realized by milling, the opening groove in the metal block 6 with the opening groove is a middle symmetrical structure, and the length of the long side of the opening groove is h 8 =12mm, width W 4 =1.65mm, length of the short side of the opening slot L 10 =4.58mm, short side width W 5=0.8mm, the opening thickness of all opening slots is W 2 =2mm, adjusting the parameters of the long side and short side of the opening slot can change the filtering performance of the metal block 6 with the opening slot. 7 is the floor of the antenna, the length and width of the floor are L 7 =56.6mm, the function of the floor 7 is to suppress the back radiation and improve the antenna gain. 8 is the coaxial port of the antenna, which is used to feed energy to the antenna.

[0015] Figure 7 The active standing waves of the low-profile ultra-wideband metal tightly coupled phased array antenna in side-firing, E-plane 45-degree scanning and H-plane 45-degree scanning under infinite boundary conditions are demonstrated. It can be seen that in the frequency band of 0.4GHz-2GHz, the active standing waves of the present invention are less than 3 when side-firing and H-plane scanning are 45 degrees, achieving a 5:1 octave bandwidth; in the frequency band of 0.4GHz-2.1GHz, the active standing waves of the present invention are less than 3 when E-plane scanning is 45 degrees, achieving a 5.25:1 octave bandwidth, which also meets the requirements for active standing waves of tightly coupled phased array antennas in engineering.

[0016] Figure 8 The present invention shows a 10×10 array, at a frequency of 1.5 GHz, the E-plane beam scanning pattern within the range of ±45 degrees, Fig. 9 The scanning pattern of the H-plane beam within the range of ±45 degrees at the same frequency is shown. It can be seen that after the present invention forms a 10×10 array, it can achieve ±45-degree beam scanning on the E-plane and H-plane, while only introducing low gain loss. The profile height of the present invention is 0.1 times the low-frequency wavelength, which achieves an extremely low profile level compared to the traditional all-metal Vivaldi antenna.

[0017] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A low-profile ultra-wideband metal tightly coupled phased array antenna, comprising a radiation structure and a feeding structure, characterized in that: The radiation structure comprises two mutually intersecting metal dipoles (1) located at the top of the overall structure for radiation and reception, an opening structure (2) loaded on the metal dipoles, a dielectric support (3) connecting the two dipoles, and a metal support (4) of a gradient structure below the metal dipoles; the feeding structure comprises a gradient metal feeding strip (5) connecting the two metal dipoles for feeding, a metal block (6) with an opening slot connected upwardly to the metal feeding strip to achieve a certain filtering function, a floor (7) located below the overall structure for suppressing back radiation, and a coaxial line (8) passing through the floor and connected to the metal block for feeding; The two mutually crossed metal dipoles (1) are connected via a dielectric support (3), and an opening structure (2) is loaded on the two metal dipoles by etching. The opening structure (2) is designed in an inverted trapezoidal shape, which is equivalent to introducing two parallel capacitors in the radiation structure to achieve better impedance matching. The metal support (4) of the gradient structure is connected to the dipole at the upper end and to the ground at the lower end, thereby ensuring the stability of the overall structure.

2. The low-profile ultra-wideband metal tightly coupled phased array antenna according to claim 1, characterized in that: The width of the gradient metal feeding strip (5) decreases from the end of the metal block (6) with the open slot to the dipole end, which can achieve a certain impedance transformation and thus impedance matching. The internal open slot structure of the metal block (6) with the open slot can be equivalent to a filter, thereby suppressing out-of-band interference. The coaxial line (8) is connected to the metal block (6) with the open slot to achieve energy feeding. The floor (7) is used to suppress back radiation and improve gain.

3. The low-profile ultra-wideband metal tightly coupled phased array antenna according to claim 1, characterized in that: The low-profile ultra-wideband metal tightly coupled phased array antenna has a lateral dimension of 56.6 mm×56.6 mm and a profile height of 75 mm.

4. The low-profile ultra-wideband metal tightly coupled phased array antenna according to claim 1, characterized in that: The dielectric pillar (3) connecting the two dipoles is in a cylindrical shape, with a relative dielectric constant of 2.2, a relative magnetic permeability of 1, a loss tangent of 0.0009, a radius of 4 mm, and a height of 75 mm.

5. The low-profile ultra-wideband metal tightly coupled phased array antenna according to claim 1, characterized in that: The opening structure (2) loaded on the metal dipole is designed in an inverted trapezoidal shape, wherein the height of the lower trapezoid is 7 mm, the short side is 7.4 mm, and the long side is 13 mm, and the height of the upper trapezoid is 7 mm, the short side is 18.6 mm, and the long side is 24.2 mm.

6. The low-profile ultra-wideband metal tightly coupled phased array antenna according to claim 1 or 2, characterized in that: The metal block (6) with the open groove is of symmetrical structure, and the width of the groove from bottom to top is 0.8mm, 0.4mm, and 0.8mm, respectively, and the length of the groove from bottom to top is 4.6mm, 7.1mm, and 4.6mm.

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