A VICTS antenna based on linear gradient tangential lobes

Abstract

The embodiment of the present disclosure relates to a VICTS antenna based on linear gradient tangent knot. The antenna comprises a radiation layer comprising a plurality of uniformly arranged tangent knot units and a fixed ring; the tangent knot unit comprises a first metal plate and a second metal plate, both of which are pentagonal in cross section; a feed layer comprising a parallel plate waveguide and a line source generator; the bottom of the parallel plate waveguide is provided with a plurality of rectangular metal long teeth which are the same in size, equidistant and parallel; the line source generator comprises a metal reflecting plate, a transition metal plate and an arc parabolic box antenna. The embodiment of the present disclosure adopts the rectangular grating slow wave structure of the tangent knot unit and the parallel plate waveguide to increase the bandwidth and the gain; by selecting tangent knot units with different lengths to form a circular array, adopting the arc parabolic box antenna as the line source generator, and using the double-layer transition waveguide structure formed by the parallel plate waveguide, the metal reflecting plate, the transition plate and the arc parabolic box antenna to realize the transmission of the plane wave, the beam scanning with a large angle in the elevation plane is realized.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the technical field of array antenna, and particularly relate to a VICTS antenna based on linear gradient transverse stub. BACKGROUND

[0002] A variable inclination continuous transverse stub (VICTS) array antenna is developed on the basis of a series-fed CTS (continuous transverse stub) antenna, and has the characteristics of high gain, low profile, wide bandwidth and beam scanning, and can be conformally installed on a mobile carrier such as a vehicle, a high-speed train or an airplane; the VICTS antenna realizes beam scanning in the elevation plane through relative rotation between a radiation plate and a feed plate, realizes beam scanning in the azimuth plane through common rotation of the two plates, and realizes accurate satellite pointing of a satellite through combination of the beam scanning characteristic and a servo control system. In related technologies, the antenna uses a leaky-wave antenna theory, has the advantages of compact structure, high gain and easy integration, and realizes two-dimensional beam scanning by changing the frequency of a waveguide or the dielectric constant of a material, but the beam scanning angle is severely limited.

[0003] Therefore, it is necessary to improve one or more problems in the related technical solutions.

[0004] It should be noted that this section aims to provide background or context to the technical solutions of the present disclosure stated in the claims. The description herein is not admitted to be prior art merely because it is included in this section. SUMMARY

[0005] Embodiments of the present disclosure aim to provide a VICTS antenna based on linear gradient transverse stub, and at least to some extent, overcome one or more problems caused by limitations and defects of related technologies.

[0006] According to embodiments of the present disclosure, a VICTS antenna based on linear gradient transverse stub is provided, which comprises:

[0007] a radiation layer comprising a plurality of uniformly arranged transverse stub units and a fixed ring;

[0008] Both ends of the transverse stub unit are fixed on the fixed ring to form a circular array, the transverse stub unit comprises a first metal plate and a second metal plate each having a pentagonal cross section, the first metal plate and the second metal plate are symmetrically arranged and form a first gap and a second gap, the bottom of the first metal plate is provided with a first long straight groove, and the bottom of the second metal plate is provided with a second long straight groove;

[0009] A feed layer, including a parallel-plate waveguide and a line source generator;

[0010] The parallel-plate waveguide is provided with a plurality of rectangular metal long teeth of the same size, equidistant and parallel arrangement, the parallel-plate waveguide is arranged at the bottom of the radiation layer, the line source generator includes a metal reflecting plate, a transition metal plate and an arc-shaped parabolic box antenna, the metal reflecting plate is connected with the arc-shaped parabolic box antenna through the transition metal plate, the parallel-plate waveguide is arranged on the transition plate and the arc-shaped parabolic box, and the parallel-plate waveguide, the metal reflecting plate, the transition plate and the arc-shaped parabolic box antenna jointly form a sector-shaped cavity, so that the plane wave can be radiated from the tangent joint unit to the free space in the transmission process.

[0011] In an embodiment of the present disclosure, the first metal plate is a pentagon formed in sequence according to a first side, an upper base, an oblique side, a second side and a lower base;

[0012] The upper base and the lower base are parallel, the length of the upper base is less than the length of the lower base, the first side and the second side are parallel and respectively perpendicular to the lower base, and the length of the first side is greater than the length of the second side.

[0013] In an embodiment of the present disclosure, the length of the first side is 9-11 mm, the length of the second side is 5-7 mm, the length of the cross section of each tangent joint unit is 15-20 mm, and the height of the parallel-plate waveguide is 8-12 mm.

[0014] In an embodiment of the present disclosure, the first gap is the distance between the maximum distance of the oblique side of the first metal plate and the oblique side of the second metal plate, and the width of the first gap is 9-11 mm;

[0015] The second gap is the distance between the minimum distance of the oblique side of the first metal plate and the oblique side of the second metal plate, and the width of the second gap is 0.3-0.7 mm.

[0016] In an embodiment of the present disclosure, the first long straight groove includes:

[0017] A circular straight groove and a first rectangular straight groove;

[0018] The circular straight groove is arranged at the top of the rectangular straight groove, and the two are connected to form the first long straight groove;

[0019] The radius of the circular straight groove is a first preset value, and the length and width of the first rectangular straight groove are a second preset value and a third preset value respectively.

[0020] In an embodiment of the present disclosure, the second long straight slot is a second rectangular slot, and a length and a width of the second rectangular slot are respectively a fourth preset value and a fifth preset value.

[0021] The first long straight slot and the second long straight slot are located at preset positions.

[0022] In an embodiment of the present disclosure, the linear source generator further comprises:

[0023] The coaxial probe and the reflector;

[0024] The coaxial probe is arranged at a focal point of the arc-shaped parabolic box antenna, and the reflector is arranged at a position close to one side of the transition metal plate and 1 / 4 wavelength away from the coaxial probe.

[0025] In an embodiment of the present disclosure, the metal reflector plate comprises:

[0026] The upper metal reflector plate, the lower metal reflector plate and the connecting plate;

[0027] The upper metal reflector plate and the lower metal reflector plate are fixed at 45° with the connecting plate and are arranged in a horn shape and gradually opened, and the lower metal reflector plate is connected with the transition metal plate.

[0028] In an embodiment of the present disclosure, the horizontal length of the transition metal plate is 5-6 mm, and the length of the upper metal reflector plate and the lower metal reflector plate in the horizontal direction is 4.5-5.5 mm.

[0029] In an embodiment of the present disclosure, the height of the inner cavity of the arc-shaped parabolic box antenna is 4.5-5.5 mm, and the thickness of the side wall of the arc-shaped parabolic box antenna is 0.5-1.5 mm.

[0030] The technical scheme provided by the embodiment of the present disclosure can have the following beneficial effects:

[0031] In the embodiment of the present disclosure, by using the VICTS antenna based on the linear gradient tangential joint, on the one hand, the rectangular grating slow wave structure of the tangential joint unit and the parallel plate waveguide is adopted to increase the bandwidth and the gain; on the other hand, by selecting the tangential joint units with different lengths to form a circular array, using the arc-shaped parabolic box antenna as a linear source generator, and using the parallel plate waveguide, the metal reflector plate, the transition plate and the arc-shaped parabolic box antenna to form a double-layer transition waveguide structure to realize the transmission of the plane wave, the large-angle beam scanning in the elevation plane is realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, further serve to explain the principles of the present disclosure. It is to be understood that the drawings are only schematic, and that they do not purport to be to scale with respect to one another. The embodiments will be described with reference to the drawings in conjunction with the detailed description, which illustrates and sets forth various embodiments of the disclosure.

[0033] Figure 1 A structural schematic diagram of a VICTS antenna based on a linear gradient tangent knot in an exemplary embodiment of the present disclosure is shown.

[0034] Figure 2 A structural schematic diagram of a tangent knot unit in an exemplary embodiment of the present disclosure is shown. Figure 1

[0035] FIG. 3(a) shows a mechanical scanning principle diagram of a VICTS antenna in an exemplary embodiment of the present disclosure.

[0036] FIG. 3(b) shows a principle diagram of horizontal incidence of an incident wave in a VICTS antenna in an exemplary embodiment of the present disclosure.

[0037] FIG. 4(a) shows a principle diagram when a radiation layer and a feed layer do not produce relative rotation in an exemplary embodiment of the present disclosure.

[0038] FIG. 4(b) shows a principle diagram when a radiation layer and a feed layer produce relative rotation in an exemplary embodiment of the present disclosure.

[0039] FIG. 5(a) shows a comparison diagram of electromagnetic field distribution before and after a matching structure is added to a VICTS antenna unit in an exemplary embodiment of the present disclosure.

[0040] FIG. 5(b) shows a comparison diagram of electromagnetic field distribution before and after a matching structure is added to a VICTS antenna unit in an exemplary embodiment of the present disclosure.

[0041] FIG. 6(a) shows a top view of an antenna array in a VICTS antenna unit in an exemplary embodiment of the present disclosure.

[0042] FIG. 6(b) shows a front view of an antenna array in a VICTS antenna unit in an exemplary embodiment of the present disclosure.

[0043] Figure 7 An H-plane pattern of a line source generator in an exemplary embodiment of the present disclosure is shown.

[0044] Figure 8 A structural schematic diagram of a double-layer transition waveguide in an exemplary embodiment of the present disclosure is shown.

[0045] FIG. 9(a) shows a S11 curve diagram of a VICTS antenna unit in an exemplary embodiment of the present disclosure.

[0046] ​Fig. 9(b) shows the S11 curve comparison of VICTS antenna element antenna array in the exemplary embodiments of the present disclosure;

[0047] Figure 10 Fig. 10 shows the 3D far field radiation pattern of VICTS antenna element at different frequency distribution in the exemplary embodiments of the present disclosure;

[0048] Fig. 11(a) shows the elevation and azimuth plane radiation pattern of VICTS antenna element in the exemplary embodiments of the present disclosure;

[0049] Fig. 11(b) shows the elevation and azimuth plane radiation pattern of VICTS antenna array in the exemplary embodiments of the present disclosure.

[0050] In the figure: 110, tangential joint unit; 111, first metal plate; 112, second metal plate; 120, fixing ring; 210, parallel plate waveguide; 220, line source generator. DETAILED DESCRIPTION

[0051] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations can be implemented in any

[0052] In addition, the drawings are merely schematic and are not drawn to scale. Identical reference numerals in the figures designate the same or similar parts throughout the figures and the detailed description. Some of the blocks in the drawings are functional blocks that do not necessarily have to be implemented in the form of physical or logical entities.

[0053] In the present example implementation, a VICTS antenna based on linear gradient tangential joint is first provided. Referring to Fig. 1, the VICTS antenna includes a fixing ring 120, a parallel plate waveguide 210, a line source generator 220, a first metal plate 111, and a second metal plate 112. Figure 1As shown in the figure, the VICTS antenna based on linear gradient tchebicon can include a radiation layer and a feed layer. The radiation layer includes a plurality of uniformly arranged tchebicon units 110 and a fixed ring 120. Both ends of the tchebicon unit 110 are fixed on the fixed ring 120 to form a circular array. The tchebicon unit 110 includes a first metal plate 111 and a second metal plate 112, both of which are pentagons in cross section. The first metal plate 111 and the second metal plate 112 are symmetrically arranged and form a first gap and a second gap. The bottom of the first metal plate 111 is provided with a first long straight groove, and the bottom of the second metal plate 112 is provided with a second long straight groove. The feed layer includes a parallel plate waveguide 210 and a linear source generator 220. The parallel plate waveguide 210 is composed of a plurality of rectangular metal long teeth with the same size, equal spacing and parallel arrangement. The parallel plate waveguide 210 is arranged at the bottom of the radiation layer. The linear source generator 220 includes a metal reflecting plate, a transition metal plate and an arc-shaped parabolic box antenna. The metal reflecting plate and the arc-shaped parabolic box antenna are connected through the transition metal plate. The parallel plate waveguide 210 is arranged on the transition plate and the arc-shaped parabolic box. The parallel plate waveguide 210, the metal reflecting plate, the transition plate and the arc-shaped parabolic box antenna together form a sector-shaped cavity, so that the plane wave can be radiated from the tchebicon unit to the free space in the transmission process.

[0054] Through the above-mentioned VICTS antenna based on linear gradient tchebicon, on the one hand, the rectangular grating slow wave structure of the tchebicon unit 110 and the parallel plate waveguide 210 is adopted to increase the bandwidth and gain. On the other hand, by selecting tchebicon units 110 with different lengths to form a circular array, and by adopting an arc-shaped parabolic box antenna as a linear source generator 220, the transmission of plane waves is realized by using the double-layer transition waveguide structure formed by the parallel plate waveguide 210, the metal reflecting plate, the transition plate and the arc-shaped parabolic box antenna, and the large-angle beam scanning in the pitch plane is realized.

[0055] In the following, the various parts of the above-mentioned VICTS antenna based on linear gradient tchebicon in the present example embodiment will be described in more detail. Figures 1 to 11(b)

[0056] In one embodiment, as shown in the figure, the first metal plate 111 is a pentagon formed in the order of a first side, an upper base, an oblique side, a second side and a lower base. The upper base and the lower base are parallel, the length of the upper base is less than the length of the lower base, the first side and the second side are parallel and perpendicular to the lower base respectively, and the length of the first side is greater than the length of the second side. Figure 2 Specifically, as shown in the figure, the second metal plate 112 is a pentagon formed in the order of a first side, an upper base, an oblique side, a second side and a lower base. The upper base and the lower base are parallel, the length of the upper base is less than the length of the lower base, the first side and the second side are parallel and perpendicular to the lower base respectively, and the length of the first side is greater than the length of the second side.

[0057] Figure 2 ​​As shown, the second metal plate 112 is symmetrically arranged with the first metal plate 111, and one first metal plate 111 and one second metal plate 112 constitute a tangential joint unit 110, and further constitute an antenna unit with the parallel plate waveguide 210 at the bottom thereof.

[0058] In one embodiment, the length of the first side is 9-11 mm, the length of the second side is 5-7 mm, and the length of the cross section of each tangential joint unit 110 is 15-20 mm, and the height of the parallel plate waveguide 210 is 8-12 mm.

[0059] Specifically, by calculating and adjusting the PPW height, the gap width, the unit spacing, the radiation branch height, etc., a VICTS antenna unit model with a linearly tapered gap branch is constructed, and some parameters of the VICTS antenna are obtained. The length of the first side h stub is 9-11 mm, the length of the second side h l is 5-7 mm, and the length of the cross section of each tangential joint unit 110 is 15-20 mm, and the height of the parallel plate waveguide 210 is 8-12 mm.

[0060] In one embodiment, the first gap is the distance between the hypotenuse of the first metal plate 111 and the hypotenuse of the second metal plate 112 at the maximum distance, and the width of the first gap is 9-11 mm; the second gap is the distance between the hypotenuse of the first metal plate 111 and the hypotenuse of the second metal plate 112 at the minimum distance, and the width of the second gap is 0.3-0.7 mm.

[0061] Specifically, in the obtained VICTS antenna unit model, the width W h of the first gap is 9-11 mm, and the width W l of the second gap is 0.3-0.7 mm.

[0062] In one embodiment, the first long straight slot includes a circular straight slot and a first rectangular straight slot; the circular straight slot is arranged at the top of the rectangular straight slot, and the two are connected to form the first long straight slot; wherein the radius of the circular straight slot is a first preset value, and the length and width of the first rectangular straight slot are a second preset value and a third preset value, respectively.

[0063] Specifically, the position of the first long straight slot on the first metal plate 111 is obtained by optimization, and the size of the first long straight slot is also obtained by optimization.

[0064] In one embodiment, the second long straight slot is a second rectangular slot, and the length and width of the second rectangular slot are a fourth preset value and a fifth preset value, respectively; wherein the positions of the first long straight slot and the second long straight slot are both preset positions.

[0065] Specifically, the position of the second long straight groove on the second metal plate 112 is obtained by optimization, and the size of the second long straight groove is also obtained by optimization.

[0066] In one embodiment, the linear source generator 220 further comprises: a coaxial probe and a reflector; the coaxial probe is arranged at the focal point of the arc-shaped parabolic box antenna, and the reflector is arranged at a position close to one side of the transition metal plate and 1 / 4 wavelength away from the coaxial probe.

[0067] Specifically, the main body of the antenna is composed of a parabolic box, the entire body is built using pec material with a dielectric constant of 1, the coaxial probe is placed at the focal point position of the parabolic box, and the reflector is placed at a position 1 / 4 wavelength away from the coaxial probe, so as to ensure that the feed source radiates in the direction of the parabolic surface, and the coaxial probe and the reflector use copper material. Due to the geometric characteristics of the parabolic surface, the TEM mode or quasi-TEM mode electromagnetic wave emitted from the focal point forms mutually parallel plane waves after being reflected by the parabolic surface.

[0068] In one embodiment, the metal reflector plate comprises: an upper metal reflector plate, a lower metal reflector plate and a connecting plate; the upper metal reflector plate and the lower metal reflector plate are both fixed at 45° with the connecting plate and are arranged in a horn shape and gradually opened, and the lower metal reflector plate is connected with the transition metal plate.

[0069] Specifically, the double-layer transition waveguide of the antenna is mainly composed of the PPW structure of the array antenna and the PPW structure of the parabolic box antenna, and the purpose is to transition the plane wave beam formed after the parabolic box antenna is reflected to the VICTS array antenna PPW input port, which is realized by using two metal reflector plates placed at 45°. Except that a long groove with a preset height is left at one end of the connection between the upper and lower metal plates, the rest of the structure is encapsulated with metal to avoid the loss of radiant energy.

[0070] The theoretical analysis of the VICTS antenna design is as follows:

[0071] As Figure 1As shown, the VICTS antenna is mainly composed of a radiation layer and a feed layer; the radiation layer is located on the upper part of the parallel plate waveguide 210 and is composed of a group of uniformly arranged tangential stubs 110; each tangential stub 110 is composed of a metal plate with a long straight slot and a matching structure; the feed layer is composed of a parallel plate waveguide (PPW) 210, a linear source generator 220 (LSG) and a linear slow wave structure; the application adopts an arc-shaped parabolic box antenna as the linear source generator 220 and uses a double-layer transition waveguide structure to realize the transmission of a plane wave. The antenna radiation principle is as follows: a TEM (Transverse Electromagnetic Wave) wave or a quasi-TEM wave is reflected by the LSG to form a plane wave; the formed plane wave is reflected by the double-layer transition waveguide structure and fed into the input end of the PPW along the axial direction and propagates forward; since the upper plate of the PPW has a number of long straight slots, the upper surface current is cut transversely, so that the electromagnetic wave is excited to radiate to the free space through the gap structure of the tangential stub.

[0072] As shown in FIGS. 3(a) and 3(b), the VICTS antenna realizes two-dimensional beam scanning through the relative rotation between the radiation layer and the feed layer; the beam scanning in the elevation plane can be realized by rotating the radiation layer, and the beam scanning in the azimuth plane can be realized by the common rotation of the radiation layer and the feed layer. Assuming that the incident wave fed into the parallel plate waveguide 210 is horizontally incident, and the rotation angle of the radiation layer is α, the length of the radiation stub is L, the bottom phase is The phase constant is β, and the upper end phase distribution of the radiation stub is seen in formula (1):

[0073]

[0074] Wherein, 0≤l≤L.

[0075] The radiation stub is processed by using the differential idea and is subdivided into radiation microelements arranged closely with each other; assuming that the distance between the microelements is dl, the phase difference between adjacent microelements is βdlsinα; according to the radiation theory of a phased array antenna, after the antenna radiation stub is rotated by an angle α, the maximum radiation direction must satisfy formula (2):

[0076]

[0077] It can be seen from formula (2) that the maximum radiation direction of the antenna deviates, which proves that the antenna can change the phase difference between adjacent array elements by rotating the radiation layer, so as to control the radiation direction of the antenna array and realize two-dimensional beam scanning.

[0078] The VICTS antenna is a linearly polarized antenna, the E-plane, the H-plane and the radiating branch are always perpendicular to each other, the antenna units are arranged in parallel along the positive direction of the Y-axis, and a right-handed coordinate system is defined according to the right-hand rule; as shown in FIG. 4(a), when the radiating layer and the feeding layer do not produce relative rotation, the antenna phase plane is parallel to the H-plane, and the main beam is directed to the E-plane; as shown in FIG. 4(b), when the radiating layer and the feeding layer produce relative rotation, the position of the antenna phase plane changes continuously, which drives the H-plane to change continuously, causing the beam to tilt; when the rotation angle θ continuously increases or decreases from 0°, the main beam can be continuously scanned in the E-plane; when the rotation angle θ is ±45°, the maximum tilt angle of the main beam is theoretically reached, but due to the interference of the rotating groove on the distribution of electromagnetic waves in the parallel plate, the main beam in the E-plane will still be slightly offset with the change of the rotation angle.

[0079] When the rotation angle is constant, the phase difference of the H-plane is determined by the PPW wavelength, and when the relative permittivity of the PPW is equal to 1, the PPW wavelength is equal to the free space wavelength; in order to increase the maximum tilt angle of the main beam, the wavelength of the PPW should be shortened as much as possible, and a common method is to fill or partially fill other materials between the PPWs to shorten the waveguide wavelength by increasing the permittivity, but this method will increase the weight and transmission loss of the antenna, and reduce the gain of the antenna; the application adopts the same height periodic slow wave structure at the bottom of the PPW to increase the equivalent permittivity of the PPW and shorten the PPW wavelength, and this method not only has small transmission loss, but also can avoid the end-fire phenomenon; the equivalent permittivity of the antenna unit after using this structure is ε e which can be calculated by formula (3), wherein β -1 is the propagation constant of the first harmonic, β0 is the free space propagation constant, and d is the center distance between adjacent antenna units in the array:

[0080]

[0081] In the related art, the closed expression of the VICTS antenna has been derived, but this formula is too complex to be applied to engineering practice; therefore, in the design of the antenna unit, the application ignores the secondary factors such as transmission loss, and approximates the radiating branch as a T-shaped interface, and the VICTS antenna unit design principle is obtained according to the proportional relationship (see formula 4).

[0082]

[0083] As can be seen from formula (4), the ratio of the slot width w to the PPW height h is proportional to the radiation coupling coefficient |K 2 |; in order to further simplify the actual operation, the PPW height h is generally fixed in engineering practice, and the radiation energy is controlled by changing the slot width w.

[0084] With the gradual increase of the radiant energy, the slot width w becomes larger and larger, thus causing the reflection coefficient to gradually deteriorate, so that the overall performance of the array behind the unit group is reduced; in order to alleviate the performance reduction speed of the array, the matching structure is introduced into both sides of the slot, which effectively reduces the reflection coefficient of the antenna. The simulation results of the unit before and after adding the matching structure are shown in Fig. 5(a) and Fig. 5(b), it can be found that with the addition of the matching structure, the electric field and magnetic field intensity on both sides of the slot are enhanced, the distribution is more concentrated, and the directivity is stronger; however, the matching unit will affect the port phase, which still needs to be considered comprehensively in the array design.

[0085] When the center distance d of adjacent elements is equal to the wavelength of the plane wave, the superposition of the reflection waves generated by each unit will deteriorate the port characteristics of the array antenna, and the grating lobe phenomenon will occur, which will increase the radiation loss, disperse the radiation energy, and reduce the effective radiation. In the array design, in order to suppress the grating lobe, the maximum value range of d is usually determined by formula (5).

[0086]

[0087] wherein λ is the wavelength of the electromagnetic wave in free space, θ is the maximum tilt angle of the main beam, and d is the center distance of the adjacent elements. In order to facilitate modeling and engineering application, the center distance d of the elements is usually slightly smaller than the wavelength of the plane wave, but this will cause a slight deviation of the main beam in the elevation plane. m

[0088] According to the above theory and principle, the antenna unit and array model working at 12-16GHz are designed, by calculating and adjusting the height of the PPW, the width of the slot, the distance between the units, the height of the radiation branch, etc., the VICTS antenna unit model with linearly tapered slot branch is constructed, the main model parameters of the optimized antenna are shown in Table 1. The antenna units are placed in parallel, and by adjusting the length of the units, a circular array with a radius of 300mm is formed, the top view and front view of the array model are shown in Fig. 6(a) and Fig. 6(b).

[0089] Table 1: Main parameters of VICTS antenna unit (unit: mm)

[0090]

[0091] Compared with the traditional VICTS antenna unit, the introduction of the linearly tapered structure and the matching structure realizes wider impedance matching characteristics, increases the bandwidth of the antenna, shortens the PPW wavelength, reduces the transmission loss, and improves the antenna gain; in order to improve the directivity of the beam transmission energy and reduce the energy leakage and dispersion, the metal plate is used to encapsulate on both sides of the feed port of the array model, and the encapsulation is shown in Fig. 7(a) and Fig. 7(b). Figure 1 ​The PPW, metal plate, feed port and antenna outer wall together form a fan-shaped cavity. This cavity, together with the radiating layer and feed layer, forms a quasi-parallel plate transmission line structure, which allows plane waves to radiate from the tangential joint into free space during transmission.

[0092] The VICTS antenna transmission structure is a PPW (Polypropylene Waveguide), whose structural characteristics require linear feed. Common linear feeds include discrete line sources such as slot arrays of rectangular waveguides, and continuous line sources such as H-plane horn antennas and parabolic antennas. Discrete line sources are difficult to fabricate, and the angular displacement of the H-plane horn antenna feed affects the aperture phase. Excessive phase difference will cause pattern distortion, leading to a significant drop in gain. Linear array antennas often use parallel or series feeding. VICTS array antennas require rotation to achieve beam scanning, and parallel feeding makes rotation inconvenient. Considering all these factors, this application selects an arc-shaped metal parabolic box antenna as the line source generator 220, and uses a double-layer transition waveguide structure to achieve plane wave transmission. Together, they form the antenna feed structure.

[0093] The main body of the arc-shaped metal parabolic antenna model consists of a parabolic box, constructed entirely of PEC material with a dielectric constant of 1. A coaxial probe is placed at the focal point of the parabolic box; a reflector is placed at a position 1 / 4 wavelength behind the coaxial probe to ensure that the feed radiates towards the parabolic surface. The coaxial probe and reflector are made of copper. Due to the geometric characteristics of the parabolic surface, TEM mode or quasi-TEM mode electromagnetic waves emitted from the focal point are reflected by the parabolic surface to form mutually parallel plane waves. The feed was modeled and simulated using ANSYS software. The simulation results of the H-plane radiation pattern of this line source generator 220 are shown in […]. Figure 7 As can be seen from the figure, the bow-shaped metal parabolic antenna feed has good directivity.

[0094] like Figure 8 As shown, the double-layer transition waveguide is mainly composed of the PPW structure of the array antenna and the PPW structure of the parabolic box antenna. The purpose is to transition the plane wave beam formed after reflection by the parabolic box antenna to the PPW input port of the VICTS array antenna. This is achieved by using two metal reflectors placed at 45°. Except for a 5.1mm long slot at the end connecting the upper and lower metal plates, the rest of the structure is encapsulated in metal to avoid the loss of radiated energy.

[0095] The following simulation examples further illustrate this embodiment.

[0096] To verify the feasibility of the design, according to the parameters in Table 1, the VICTS antenna unit and array proposed above were modeled and full-wave simulated by ANSYS HFSS software; at the same time, the antenna was manufactured according to the optimized size by numerical control machining process, and the physical antenna was measured in the microwave anechoic chamber. The results show that in the working frequency range of 12-16 GHz, the reflection coefficient of the array antenna measured by Agilent N5230A and the S11 parameter of the array model calculated by the simulation software are both less than -10 dB (see Figure 9), both of which can meet the engineering needs. The error between them may be caused by the antenna processing precision and the loose packaging.

[0097] Figure 10 The 3D far-field radiation pattern of the antenna unit at different frequencies is reflected. As can be seen from the figure, the unit radiation pattern has little to do with the frequency point selection, and the radiation energy is mainly distributed in a ring or plane shape, with a small part of end-fire and leakage energy on both sides and the bottom of the slot; when the frequency point tends to be high, the energy distribution shape is slightly deformed, but it has little effect on the radiation direction, which proves that the antenna unit has good directivity in the frequency range of 12-16 GHz.

[0098] Figure 11(a) shows the radiation pattern of the antenna unit in the elevation plane and the azimuth plane at 14.5 GHz, from which it can be seen that the maximum gain of the antenna unit in the elevation plane and the azimuth plane is 22.6 dB, and the sidelobe level is low; Figure 11(b) shows the radiation pattern of the physical antenna measured by the planar near-field measurement method and the radiation pattern of the antenna array simulated by ANSYS in the elevation plane and the azimuth plane at 14.5 GHz, from which it can be seen that the measured pattern and the simulation pattern have high consistency, the main lobe beam width of both is narrow, the energy is concentrated, and they have good directivity, but due to the mutual coupling and influence between each unit, the sidelobe level increases significantly. The maximum gain of the simulation pattern in the elevation plane is 34.3 dB, and the measured pattern is about 1 dB lower than the simulation pattern, which may be due to the machining precision and the loose packaging, but it does not have a great impact on the beam scanning performance of the antenna, as can be seen from the figure, the beam pointing of both is nearly consistent. Figure 1

[0099] ​When the radiation layer and the feed layer do not produce relative rotation, it can be known that the beam pointing of the measured result and the simulation result of the antenna are approximately consistent, and the antenna has obvious frequency scanning characteristics, that is, the beam scanning in the elevation plane can be realized by changing the center frequency of the antenna; in the frequency range of 12-16 GHz, the beam scanning range of the array antenna in the elevation plane is-21°-7°, and the antenna gain decreases by not more than 7 dB; it can be known from the above that even if the radiation layer and the feed layer do not rotate, the main beam will still produce a shift in the vertical direction, and the shift angle is basically consistent with the elevation angle calculated by the uniform linear array theory, which is due to the fact that the VICTS antenna is a traveling wave antenna.

[0100] At 14.5 GHz, the 3D far-field radiation data corresponding to the rotation angles of 0°, 20°, 40° and 50°; it can be known from the above that the beam pointing of the measured structure and the simulation result is basically consistent at a lower rotation angle, and when the rotation angle gradually increases, there will be a slight shift; when the rotation angle is between 0-20°, the antenna gain decreases by less than 2 dB, when the rotation angle is between 20-40°, the antenna gain decreases obviously, and the side lobe level increases significantly, but the main lobe and side lobe levels can still be distinguished at this time; when the rotation angle is between 40-50°, especially greater than 45°, the main lobe and side lobe levels are difficult to distinguish, at this time, it is obviously not feasible to determine the elevation angle of the main beam only by the size of the received level, but in this rotation range, the spatial distinction of the main lobe and side lobe is still relatively obvious, and there is still a unique maximum level in the estimated angle range; in this case, in order to determine the elevation angle of the main beam, the servo control system should be combined to determine the elevation angle of the main beam by comparing and judging the maximum receiving level in the estimated region. When the rotation angle is greater than 60°, the radiation energy of the array antenna is extremely dispersed, there is no obvious spatial distinction between the main lobe and side lobe levels, and there are many main lobe and side lobe levels with similar sizes and different directions in the entire radiation region, at this time, it is difficult to realize beam scanning even by combining the servo control system.

[0101] It can be known from the above that the beam scanning angle increases with the increase of the rotation angle, and the 3dB beam width also increases but is still relatively narrow overall, and there is a nonlinear corresponding relationship between the two. When the rotation angle is 0-40°, the corresponding scanning angle is 6-54°, and the 3dB beam width basically remains within 7°, in combination with the servo control system, the rotation angle can be increased to 50°, the corresponding scanning angle can be increased to 79°, and the 3dB beam width is also not more than 10°; when the radiation layer and the feed layer rotate clockwise, due to the symmetry of the circular antenna, it can be known that the elevation angle scanning range is still 6-79°.

[0102] In recent years, the academia has carried out extensive exploration and research on the application of VICTS antennas, and designed various types of VICTS antennas. The scanning characteristics of the antenna designed in the present application compared with the CTS antennas and VICTS antennas published are shown in Table 2. From the data comparison, it can be seen that the scanning range of the new antenna is slightly improved.

[0103] Table 2: Comparison of beam scanning characteristics of beam scanning antennas in different literatures

[0104]

[0105] In summary, the VICTS unit with linearly tapered branch and array model are proposed in the present application, and modeling and full-wave simulation are carried out. The parabolic arch-shaped metal box structure and double-layer waveguide structure are used as the antenna feed source, and the antenna is also manufactured and tested. The full-wave simulation results and the test results prove that the antenna unit and array designed in the present application have the characteristics of high gain, narrow beam and low profile, and can realize the beam scanning in the range of 6-79° and -6--79° in the elevation plane. Compared with the traditional VICTS antenna, the beam scanning performance is slightly improved. With the increase of the rotation angle of the radiation layer and the feed layer, the main lobe gain of the array antenna decreases rapidly, and the side lobe level increases obviously.

[0106] It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like in the above description indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0107] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0108] In the embodiments of the present disclosure, unless specifically defined and limited otherwise, the terms "mount", "connect", "connection", "fixed", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0109] In the embodiments of the present disclosure, unless specifically defined and limited otherwise, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0110] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the specification.

[0111] Other embodiments of the present disclosure will be apparent to those skilled in the art upon consideration of the specification and practice of the applications disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles thereof and include the general principles thereof and include those known or customary practice in the art to which the present disclosure pertains. The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A VICTS antenna based on linear gradient tangential sections, characterized in that, The antenna comprises: a radiation layer comprising a fixed ring and a plurality of uniformly arranged tangent knot units; two ends of the tangent knot units are fixed on the fixed ring to form a circular array, the tangent knot units comprise a first metal plate and a second metal plate each in a pentagonal cross section, the first metal plate and the second metal plate are symmetrically arranged and form a first gap and a second gap, a first long straight groove is arranged at the bottom of the first metal plate, and a second long straight groove is arranged at the bottom of the second metal plate, and the tangent knot units are arranged to form a circular array; the first gap is a spacing at a maximum distance between the oblique edge of the first metal plate and the oblique edge of the second metal plate; the second gap is a spacing at a minimum distance between the oblique edge of the first metal plate and the oblique edge of the second metal plate; the first long straight groove comprises: a circular straight groove and a first rectangular straight groove; the circular straight groove is arranged at the top of the rectangular straight groove, and the two are connected to form the first long straight groove; wherein the radius of the circular straight groove is a first preset value, and the length and width of the first rectangular straight groove are a second preset value and a third preset value respectively; the second long straight groove is a second rectangular groove, and the length and width of the second rectangular groove are a fourth preset value and a fifth preset value respectively; wherein the positions of the first long straight groove and the second long straight groove are preset positions; a feeding layer comprising a parallel plate waveguide and a linear source generator; the bottom of the parallel plate waveguide is provided with a plurality of rectangular metal long teeth which are the same in size, equally spaced and arranged in parallel, the parallel plate waveguide is arranged at the bottom of the radiation layer, the linear source generator comprises a metal reflecting plate, a transition metal plate and an arc-shaped parabolic box antenna, the metal reflecting plate and the arc-shaped parabolic box antenna are connected through the transition metal plate, the parallel plate waveguide is arranged on the transition metal plate and the arc-shaped parabolic box, and the parallel plate waveguide, the metal reflecting plate, the transition metal plate and the arc-shaped parabolic box antenna jointly form a sector-shaped cavity, so that a plane wave can be radiated from the tangent knot units to free space in the transmission process.

2. The VICTS antenna based on linear gradient tangential sections according to claim 1, characterized in that, The first metal plate is a pentagon formed by sequentially arranging a first side, an upper base, an oblique edge, a second side and a lower base; wherein the upper base and the lower base are parallel, the length of the upper base is smaller than the length of the lower base, the first side and the second side are parallel and perpendicular to the lower base respectively, and the length of the first side is greater than the length of the second side.

3. The VICTS antenna based on linear gradient tangential sections according to claim 2, characterized in that, The length of the first side is 9-11 mm, the length of the second side is 5-7 mm, and the length of the cross section of each tangent knot unit is 15-20 mm, and the height of the parallel plate waveguide is 8-12 mm.

4. The VICTS antenna based on linear gradient tangential sections according to claim 1, characterized in that, The width of the first gap is 9-11 mm, and the width of the second gap is 0.3-0.7 mm.

5. The VICTS antenna based on linear gradient tangential sections according to claim 1, characterized in that, The linear source generator further comprises: a coaxial probe and a reflector; the coaxial probe is arranged at the focal point of the arc-shaped parabolic box antenna, and the reflector is arranged at a position close to the transition metal plate and 1 / 4 wavelength away from the coaxial probe.

6. The VICTS antenna based on linear gradient tangential sections according to claim 1, characterized in that, The metal reflecting plate comprises: an upper metal reflecting plate, a lower metal reflecting plate and a connecting plate; The upper metal reflecting plate and the lower metal reflecting plate are fixed at 45 degrees with the connecting plate and gradually open like a horn, and the lower metal reflecting plate is connected with the transition metal plate.

7. The VICTS antenna based on linear gradient tangential sections according to claim 6, characterized in that, The horizontal length of the transition metal plate is 5-6 mm, and the length of the upper metal reflecting plate and the lower metal reflecting plate in the horizontal direction is 4.5-5.5 mm.

8. The VICTS antenna based on linear gradient tangential sections according to claim 1, characterized in that, The height of the inner cavity of the arc-shaped parabolic box antenna is 4.5-5.5 mm, and the thickness of the sidewall of the arc-shaped parabolic box antenna is 0.5-1.5 mm.

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