A broadband low-profile dual-polarized Vivaldi antenna unit with a novel feeding structure

Abstract

The application discloses a broadband low-profile dual-polarized Vivaldi antenna unit with a novel feeding structure, comprising a metal floor, a dielectric feeding layer, a metal antenna unit and two radio frequency connectors, the metal antenna unit comprises two mutually perpendicular single-polarized units, and the two single-polarized units are connected to each other, and the connection part shares a metal column, the two single-polarized units are of the same structure, the dielectric feeding layer is arranged between the metal floor and the metal antenna unit, the two radio frequency connectors are arranged in the metal floor, and the probes of the two radio frequency connectors feed the two single-polarized units after penetrating through the dielectric feeding layer. The feeding structure in the application is easy to weld, can guarantee the stable connection between the radio frequency connector and the antenna structure, and has the advantages of simple structure, easy processing and universality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wideband array antennas, and particularly relates to a wideband low-profile dual-polarized Vivaldi antenna unit with a novel feeding structure. BACKGROUND

[0002] With the continuous development of radar detection, electronic countermeasures and wireless communication technologies, there are higher and higher requirements for the performance of antennas. On modern moving platforms such as airplanes and warships, dozens or even hundreds of antennas are often installed to meet the needs of radar, communication, electronic support and electronic jamming. It is very difficult to ensure that the installation positions of the antennas can fully exert the performance indicators of the antennas and also take into account the electromagnetic compatibility among the antennas. At the same time, dozens of different types of antennas distributed in various parts of the airplane have a great influence on the aerodynamic performance and stealth performance of the airplane. Due to the limited space of the airborne platform, when designing the airborne antenna, the size of the antenna should be reduced as much as possible, and it is hoped that one antenna can realize multiple functions such as radar, communication and electronic countermeasures, which requires the antenna to have the characteristics of low profile, ultra-wideband, miniaturization and the like. In particular, with the development of integrated communication and radar, the communication antenna and the radar antenna are combined and designed, and the integrated electronic information system is integrated, which not only can improve the data transmission capacity, but also can greatly reduce the space occupied by the radio frequency link on the airplane, and has great practical significance. The Vivaldi antenna is a planar end-fire tapered slot antenna, which is widely used in the ultra-wideband field due to its wide operating frequency band, good directivity, high gain and the like, and simple structure and easy integration.

[0003] The Vivaldi antenna has attracted great attention and development since it was proposed due to its ultra-wideband performance. At present, there are mainly dielectric substrate type and all-metal type. The dielectric substrate type can be made by printed circuit technology, which is simple to process, but the mechanical strength is not enough. The all-metal Vivaldi antenna can achieve high mechanical strength as a whole, and is more suitable for harsh working environments, but due to its structural characteristics, it is difficult to weld the radio frequency connector probe with the antenna structure, and it is difficult to guarantee the stability of the feeding only by the contact of the probe vertex with the antenna.

[0004] For example, in 2020, Li Zhe et al. published a patent entitled "An Ultra-Wideband Wide-Angle Scanning All-Metal Vivaldi Array Antenna" (Application No: CN 202010836729.8), which designed a single-polarized antenna working in the 0.8-6 GHz frequency band by using a radio frequency connector direct insertion feeding method. Although this feeding structure is simple, considering various errors caused by mechanical processing and radio frequency connector production, it is difficult to ensure the stable connection of the radio frequency connector with the antenna.

[0005] For example, in 2019, Wang Yaju et al. designed a double-polarized antenna structure that can be welded in a patent entitled "Double-polarized metal tapered slot antenna, array antenna and method of L-shaped connector" (application number: CN 201910326274.2). The antenna structure is cut open and placed into a radio frequency connector before welding. However, the processing method of cutting and reassembling the antenna structure is complex and prone to more processing errors. SUMMARY

[0006] The purpose of the present application is to provide a broadband low-profile dual-polarized Vivaldi antenna unit with a new type of feed structure. The optimized feed structure is easy to weld and simple in structure. The antenna profile is low and has good broadband performance.

[0007] The technical solution to achieve the purpose of the present application is: a broadband low-profile dual-polarized Vivaldi antenna unit with a new type of feed structure, comprising a metal ground plate, a dielectric feed layer, a metal antenna unit, and two radio frequency connectors; the metal antenna unit includes two mutually perpendicular single-polarized units, the unit structures are the same, and the two single-polarized units are connected to each other and share a metal column, the single-polarized unit includes a tapered slot, a uniform straight slot, a matching cavity, and a wedge-shaped tip; the dielectric feed layer is arranged between the metal ground plate and the metal antenna unit, and the two radio frequency connectors pass through the metal ground plate; the dielectric feed layer includes a Teflon dielectric layer and a rectangular metal patch, the rectangular metal patch is located at the junction of the Teflon dielectric layer and the upper surface of the uniform straight slot, the probes of the radio frequency connectors are connected to the Teflon dielectric layer and the rectangular metal patch, and the rectangular metal patch is connected to the uniform straight slot of the metal antenna unit for feeding; the probes of the two radio frequency connectors pass through the dielectric feed layer to feed the two single-polarized units one by one.

[0008] Preferably, the tapered slot is on both sides of the longitudinal central axis of the single-polarized unit, the starting end of the slot line is the junction of the single-polarized unit and the upper surface of the dielectric feed layer, and the slot line opening gradually increases in the direction opposite to the starting segment; a uniform straight slot parallel to the metal ground plate is formed by slotting from the starting end of the tapered slot towards the shared metal column; the matching cavity is arranged on the side of the tapered slot close to the shared metal column and communicates with the uniform straight slot.

[0009] Preferably, the matching cavity is trapezoidal and connected to the uniform straight slot and the tapered slot.

[0010] Preferably, the tapered slot has three straight lines with different slopes, and the opening rate gradually increases from one end to the other end.

[0011] Preferably, the Teflon dielectric layer is located between the metal antenna unit and the metal ground plate, only the part of the dielectric located in the uniform straight slot is reserved, and the rest is excavated, so that the metal antenna unit is connected with the metal ground plate.

[0012] Compared with the prior art, the present application has the following advantages:

[0013] The feeding structure in the present application is easy to weld, can ensure stable connection of the radio frequency connector and the antenna structure, and has simple structure and universality.

[0014] The wedge-shaped structure at the top end of the antenna structure in the present application can effectively adjust the high-frequency part impedance matching of the antenna, and improves the flexibility of Vivaldi antenna impedance adjustment.

[0015] The antenna structure in the present application is all-metal, can be fixed on the metal ground plate through screws, and has high structural strength. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a full view of a wideband dual-polarized Vivaldi antenna unit.

[0017] Figure 2 is a front view of a wideband dual-polarized Vivaldi antenna unit.

[0018] Figure 3 is a full view of a feeding structure of a wideband dual-polarized Vivaldi antenna unit.

[0019] Figure 4 is a change trend of the standing wave ratio of an infinite large periodic model of a wideband dual-polarized Vivaldi antenna under a normal angle with the slot line opening Ws.

[0020] Figure 5 is a change trend of the standing wave ratio of an infinite large periodic model of a wideband dual-polarized Vivaldi antenna under a 45° scanning angle in the H plane with the edge length W of the wedge-shaped tip.

[0021] Figure 6 is a change trend of the standing wave ratio of an infinite large periodic model of a wideband dual-polarized Vivaldi antenna under a normal angle with the slot line width Hs of the uniform straight slot.

[0022] Figure 7 is the standing wave ratio of an infinite large periodic model of a wideband dual-polarized Vivaldi antenna under a normal angle, a 30° scanning angle and a 45° scanning angle in the E plane.

[0023] Figure 8 is the standing wave ratio of an infinite large periodic model of a wideband dual-polarized Vivaldi antenna under a normal angle, a 30° scanning angle and a 45° scanning angle in the H plane.

[0024] Figure 9 is the port isolation of the wideband dual-polarized Vivaldi antenna infinite periodic model at the normal angle and 45° scanning angle.

[0025] Figure 10 is the main polarization gain and cross-polarization gain of the wideband dual-polarized Vivaldi antenna infinite periodic model. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further described in detail below in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation manners and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0027] The concept of the present application is a wideband low-profile dual-polarized Vivaldi antenna unit with a novel feeding structure, which comprises a metal floor 3, a dielectric feeding layer 2, a metal antenna unit 1, and two radio frequency connectors 4. The metal antenna unit 1 comprises two mutually perpendicular single-polarized units, which have the same unit structure and are connected to each other and share a metal column. The single-polarized unit comprises a tapered slot 12, a uniform straight slot 13, a matching cavity 14, and a wedge-shaped tip 11. The dielectric feeding layer 2 is arranged between the metal floor 3 and the metal antenna unit 1, and the two radio frequency connectors 4 pass through the metal floor 3. The dielectric feeding layer comprises a Teflon dielectric layer 22 and a rectangular metal patch 21. The rectangular metal patch 21 is located at the junction of the Teflon dielectric layer 22 and the upper surface of the uniform straight slot 13. The probes of the radio frequency connectors 4 are connected to the Teflon dielectric layer 22 and the rectangular metal patch 21, and the rectangular metal patch 21 is connected to the uniform straight slot of the metal antenna unit 1 for feeding. The probes of the two radio frequency connectors 4 pass through the dielectric feeding layer 2 to feed the two single-polarized units one by one.

[0028] In a further embodiment, the tapered slot (12) is on both sides of the longitudinal axis of the single-polarized unit, the starting end of the slot line is the joint of the single-polarized unit and the upper surface of the dielectric feed layer (2), and the slot line opening gradually increases in the direction opposite to the starting segment; the uniform straight slot (13) parallel to the metal floor is formed by slotting from the starting end of the tapered slot (12) to the direction of the common metal column; the matching cavity (14) is arranged on the side of the tapered slot (12) close to the common metal column and communicates with the uniform straight slot (13); when the antenna is working, energy is fed into the uniform straight slot (13) structure through the coaxial feed, and induced current is generated on the metal walls on both sides of the slot line and flows to both sides along the slot line; the connection structure of the matching cavity (14) and the uniform straight slot (13) is an open circuit structure, and the current transmitted to this side is reflected by the matching cavity (14) to the other side of the slot line, so that most of the energy is transmitted to the tapered slot (12) part through the uniform straight slot (13) and continues to propagate upwards, and finally forms radiation.

[0029] In a further embodiment, the matching cavity (14) is trapezoidal, connected with the uniform straight slot (13) and the tapered slot (12), and limited by the inclined tapered slot (12), in order to design a matching cavity (14) with sufficient size in a limited area, the traditional rectangular cavity is designed as a trapezoidal cavity.

[0030] In a further embodiment, the tapered slot (12) has three straight lines with different slopes, and the opening rate gradually increases from one end to the other end, and as the slot line gradually opens, the binding force of the slot line to the electromagnetic wave gradually decreases, so as to realize the radiation of the electromagnetic wave to the air.

[0031] In a further embodiment, the Teflon dielectric layer (22) is located between the metal antenna unit (1) and the metal floor (3), only the part of the dielectric located in the uniform straight slot (13) is reserved, and the remaining part is excavated, so that the metal antenna unit (1) is connected with the metal floor (3), thereby ensuring good electrical contact between the radio frequency connector and the metal antenna unit.

[0032] In the application, the edge length of the wedge-shaped pointed top 11 is W, and by adjusting the edge length, the impedance matching performance of the high-frequency part during scanning can be effectively adjusted.

[0033] In the present application, the point contact feeding of the probe inconvenient for welding in the previous structure is optimized to the weldable surface pressure feeding with medium as transition. In the traditional all-metal Vivaldi antenna structure, the probe is often contacted to the upper surface of the uniform straight slot to realize the connection of the radio frequency connector and the antenna. Considering the machining error and other factors, the contact point with a diameter less than 1mm is not stable, and the slot line is generally thin, so the welding gun is difficult to extend into, and the probe and the antenna cannot be ensured to be in good contact through welding. In the present application, a medium layer is introduced between the antenna and the metal floor, and a metal patch is printed on the part where the upper surface of the medium layer and the upper surface of the uniform straight slot meet, so that the probe passes through the medium layer and is connected with the metal patch. The probe and the metal patch are welded together during processing, and finally the antenna is pressed on the medium, so that the uniform straight slot and the metal patch are tightly pressed together, thereby ensuring the stability of the feeding. Through the optimization of the size of the tapered slot, the width of the uniform straight slot and the top structure of the antenna, the antenna can be well applied to the frequency band of 3-18.5GHz. The present application has the advantages of wide frequency band, large angle scanning, easy welding, simple processing, stable structure and high engineering application value.

[0034] Embodiment

[0035] As shown in Figures 1-3 A broadband low-profile dual-polarized Vivaldi antenna unit with a novel feeding structure, comprising a metal floor (3), a medium feeding layer (2), a metal antenna unit (1) and two radio frequency connectors (4); the metal antenna unit (1) comprises two mutually perpendicular single-polarized units, the unit structures are the same, and the two single-polarized units are connected with each other and share a metal column, the single-polarized unit comprises a tapered slot (12), a uniform straight slot (13), a matching cavity (14) and a wedge-shaped tip (11); the medium feeding layer (2) is arranged between the metal floor (3) and the metal antenna unit (1), and the two radio frequency connectors (4) pass through the metal floor (3); the medium feeding layer comprises a Teflon medium layer (22) and a rectangular metal patch (21), the rectangular metal patch (21) is located at the joint of the Teflon medium layer (22) and the upper surface of the uniform straight slot (13), the probe of the radio frequency connector (4) is connected with the rectangular metal patch (21) through the Teflon medium layer (22), and the rectangular metal patch (21) is connected with the uniform straight slot of the metal antenna unit (1) for feeding, the probes of the two radio frequency connectors (4) pass through the medium feeding layer (2) to correspondingly feed the two single-polarized units.

[0036] The gradient groove (12) is located on both sides of the longitudinal central axis of the single polarization unit. The starting end of the groove line is the junction of the single polarization unit and the upper surface of the dielectric feed layer (2). The opening of the groove line gradually increases in the opposite direction to its starting section. A uniform straight groove (13) parallel to the metal floor is formed by slotting from the starting end of the gradient groove (12) towards the common metal column. The matching cavity (14) is located on the side of the gradient groove (12) close to the common metal column and is connected to the uniform straight groove (13).

[0037] In practice, a gradient groove (12), a uniform straight groove (13), a matching cavity (14), and a wedge-shaped tip (11) are cut out on the aluminum plate.

[0038] The gradient groove (12) consists of three straight gradient groove lines with different slopes, whose opening ratio gradually increases to form a gradually widening radial groove. The size of the opening Ws in the middle of the groove line simultaneously affects the slope of the first and second groove lines. For example... Figure 4 As shown, when Ws is too small, the low-frequency matching is poor, indicating that at this time, the small aperture and small slope are insufficient to support the normal operation of the low frequency; when Ws is too large, it affects the impedance matching of the high frequency.

[0039] The wedge-shaped tip (11) has a side length of W. Adjusting its side length can effectively regulate the impedance matching performance of the high-frequency portion during scanning. Given a fixed unit size and aluminum plate thickness, adjusting the side length W of the wedge-shaped tip (11) is equivalent to adjusting the size Wa of the opening at the top of the antenna. Figure 5 As shown, at a 45° scanning angle in the H plane, if the top of the antenna is not wedge-shaped, i.e., the side length W is equal to the thickness of the aluminum plate (4 mm), the opening size Wa is small, resulting in poor impedance matching in the high-frequency section. However, as W decreases (i.e., the antenna opening size Wa increases), the impedance matching in the high-frequency section is optimized.

[0040] The matching cavity (14) is trapezoidal and is connected to the gradient groove (12) through a uniform straight groove (13).

[0041] The Teflon dielectric layer (22) is partially removed to allow the metal antenna element (1) to connect to the metal ground plane (3), i.e., to fix the metal antenna element (1) to the metal ground plane (3) with screws. The thickness of the Teflon dielectric layer (22) is equal to the width of the uniform straight groove (13), both being Hs. Figure 6 As shown, simulations revealed that the width of the uniform straight groove (13) has a significant impact on impedance matching across the entire frequency band.

[0042] The probe of the radio frequency connector (4) is connected with the rectangular metal patch (21) through a Teflon medium layer (22), and soldering is used to ensure stable connection of the probe and the rectangular metal patch (21) during processing, the rectangular metal patch (21) is connected with the upper surface of the uniform linear groove (13), thereby ensuring good electrical contact between the radio frequency connector and the metal antenna unit.

[0043] Further, the metal antenna unit (1) has a height H of 28.3 mm (0.283 ).

[0044] As shown in Figure 7 and Figure 8 , after parameter optimization, the wideband dual-polarized Vivaldi antenna infinite periodic model has a normal angle VSWR less than 2, an E-plane and H-plane VSWR less than 3 at a 45° scanning angle, and good full-band and wide-angle matching.

[0045] As shown in Figure 9 , after parameter optimization, the wideband dual-polarized Vivaldi antenna infinite periodic model has a port isolation greater than 20 dB at a normal angle and a 45° scanning angle, and good port isolation.

[0046] As shown in Figure 10 , after parameter optimization, the wideband dual-polarized Vivaldi antenna infinite periodic model has a polarization isolation (difference between main polarization gain and cross-polarization gain) greater than 25 dB at a normal angle, and good polarization isolation.

Claims

1. A broadband low-profile dual-polarized Vivaldi antenna element with a novel feeding structure, characterized in that, The antenna includes a metal ground plane (3), a dielectric feed layer (2), a metal antenna element (1), and two radio frequency connectors (4). The metal antenna element (1) includes two mutually perpendicular single-polarization units with identical unit structures. The two single-polarization units are interconnected and share a common metal pillar. The single-polarization unit includes a gradient slot (12), a uniform straight slot (13), a matching cavity (14), and a wedge-shaped tip (11). The dielectric feed layer (2) is disposed between the metal ground plane (3) and the metal antenna element (1). The two radio frequency connectors (4) pass through the metal ground plane (3). The dielectric feed layer includes a Teflon dielectric layer (22) and a rectangular metal patch (21). The metal patch (21) is located at the junction of the Teflon dielectric layer (22) and the upper surface of the uniform straight groove (13). The probe of the RF connector (4) passes through the Teflon dielectric layer (22) and is connected to the rectangular metal patch (21). The rectangular metal patch (21) is connected to the uniform straight groove of the metal antenna unit (1) for power feeding. The probes of the two RF connectors (4) pass through the dielectric feeding layer (2) to feed the two single polarization units one-to-one. The matching cavity (14) is trapezoidal and is connected to the gradient groove (12) through the uniform straight groove (13). The gradient groove (12) has three straight gradient lines with different slopes, and the aperture ratio gradually increases from one end to the other end.

2. The broadband low-profile dual-polarized Vivaldi antenna element with a novel feeding structure according to claim 1, characterized in that, The gradient groove (12) is located on both sides of the longitudinal central axis of the single polarization unit. The starting end of the groove line is the junction of the single polarization unit and the upper surface of the dielectric feed layer (2). The opening of the groove line gradually increases in the opposite direction to its starting section. A uniform straight groove (13) parallel to the metal floor is formed by slotting from the starting end of the gradient groove (12) towards the common metal column. The matching cavity (14) is located on the side of the gradient groove (12) close to the common metal column and is connected to the uniform straight groove (13).

3. The broadband low-profile dual-polarized Vivaldi antenna element with a novel feeding structure according to claim 1, characterized in that, The portion of the Teflon dielectric layer (22) located between the metal antenna unit (1) and the metal ground plane (3) retains only the portion of the dielectric located in the uniform straight groove (13), while the rest is removed, so that the metal antenna unit (1) is connected to the metal ground plane (3).

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