A four-beam frequency scanning leaky-wave antenna

Abstract

The present invention discloses a four-beam frequency scanning leaky wave antenna, which works in the millimeter wave band and is composed of upper and lower metal panels, a dielectric layer and a metal tube. Combining the periodic sinusoidal impedance modulation theory with the artificial surface plasmon technology, by periodically slotting the surface of the dielectric integrated waveguide, the higher harmonics of the transmitted electromagnetic waves are excited, and directional radiation is generated outward to achieve target detection. For four-cycle sinusoidal impedance modulation, within a certain operating frequency, electromagnetic waves can be scanned simultaneously in four directions. In addition, slots are also opened on the back of the dielectric integrated waveguide so that the radiation of the upper and lower parts in the direction of the feed source cancels each other, reducing the energy leakage in the direction of the feed source, effectively suppressing the bandgap effect, and finally achieving side emission. Compared with traditional frequency scanning antennas, the antenna of the present invention has the characteristics of easy processing, multi-beam, high frequency band utilization and side emission.

Description

Technical Field

[0001] The invention relates to the technical fields of microwave, wireless communication and test simulation, in particular to a four-beam frequency scanning leaky wave antenna based on periodic sinusoidal impedance modulation. Background Art

[0002] Frequency scanning antenna, an antenna that achieves beam scanning by controlling the feeding frequency. Compared with traditional mechanical scanning antennas, it has the advantages of easy processing and low cost. Artificial surface plasmon is a phenomenon caused by the interaction between electromagnetic waves and metal surfaces. In this case, the electromagnetic waves will be tightly bound to the metal surface and propagate along the metal surface.

[0003] The leaky wave antenna based on artificial surface plasmon is a type of frequency scanning antenna. According to the sinusoidal impedance modulation theory, by periodically slotting the surface of the dielectric integrated waveguide, directional radiation of the beam can be achieved; as the frequency changes, the beam can be continuously scanned in space.

[0004] Since the above antennas often do not have the ability to detect multiple targets, in order to improve the channel capacity of the antenna and realize the function of multi-target detection, a better scanning leaky-wave antenna is urgently needed. Summary of the invention

[0005] The purpose of the present invention is to propose a four-beam frequency scanning leaky wave antenna. According to the periodic sinusoidal impedance modulation theory, periodic slots are made on the dielectric integrated waveguide to achieve simultaneous scanning of four beams and effectively reduce the working bandwidth of the antenna. It has the characteristics of easy processing, multi-beam, high frequency band utilization, and side-fire. It improves the channel capacity of the antenna and the ability to achieve multi-target detection.

[0006] The specific technical solution for achieving the purpose of the present invention is:

[0007] A four-beam frequency scanning leaky wave antenna, characterized in that: it comprises a top metal panel, a dielectric substrate, a bottom metal panel and a metal tube, wherein the top metal panel, the dielectric substrate, the bottom metal panel and the metal tube are all arranged in the same rectangular coordinate system; wherein:

[0008] The top metal panel is a rectangle, with the center of the short side of the rectangle as the origin, the long side direction as the X axis, the short side direction as the Y axis, and the Z axis perpendicular to the rectangle as the Z axis to establish a rectangular coordinate system; the top metal panel is divided into the first quadrant and the fourth quadrant by the rectangular coordinate system; the top metal panel is provided with a middle straight line formed by a plurality of through holes as edges and a symmetrical area formed by Y-shaped connections at both ends, and a narrow array composed of a plurality of unequal lengths of gaps is provided in the middle of the symmetrical area; and a gradient slit is opened inwardly at the upper part of the Y-shaped at both ends of the symmetrical area;

[0009] The dielectric substrate is rectangular and has the same length and width as the top metal panel; a symmetrical area is provided on the dielectric substrate, which has the same size and shape as the top metal panel and is formed by a straight line in the middle formed by a plurality of through holes as edges and two ends connected in a Y shape;

[0010] The bottom metal panel is rectangular and has the same length and width as the dielectric substrate; the bottom metal panel is provided with a symmetrical area formed by a straight line in the middle formed by a plurality of through holes and connected in a Y shape at both ends, which is the same size and shape as the top metal panel; a narrow array composed of a plurality of slits of different lengths and the same size and shape as the top metal panel is provided in the middle of the symmetrical area; an isosceles triangular slot is provided on the Y shape at both ends of the symmetrical area;

[0011] There are several metal tubes, which penetrate through the through holes forming the symmetrical area edges on the dielectric substrate, and are respectively inserted into the through holes forming the symmetrical area edges on the top metal panel and the bottom metal panel, so as to bond the top metal panel, the dielectric substrate and the bottom metal panel into one body;

[0012] The top metal panel, the dielectric substrate and the bottom metal panel are symmetrically provided with test fixing holes at both ends.

[0013] The slot array is an impedance modulation area; the lower part of the Y-shape at both ends is a feeding coplanar waveguide, and the upper part of the Y-shape between the impedance modulation area and the feeding coplanar waveguide is a transition structure.

[0014] The dielectric substrate is made of Rojers Ro4003C high-frequency material plate, and the top metal panel and the bottom metal panel are made of metal copper plates.

[0015] Beneficial effects of the present invention

[0016] Compared with the traditional frequency scanning antenna, the antenna of the present invention has the characteristics of easy processing, multi-beam, high frequency band utilization, side-fire, etc. Therefore, it can be promoted and applied to future 5G and 6G communication systems to expand the utilization of spectrum, increase the capacity of communication channels, and improve data transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the top metal panel of the present invention;

[0019] Figure 3 It is a structural schematic diagram of the dielectric substrate of the present invention;

[0020] Figure 4 It is a schematic diagram of the structure of the bottom metal panel of the present invention;

[0021] Figure 5 It is a schematic diagram of the directions of four beams radiated by the antenna in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0023] See also Figure 1-4 The four-beam frequency scanning leaky wave antenna of the present invention comprises a top metal panel 1, a dielectric substrate 2, a bottom metal panel 3 and a metal tube 4, wherein the top metal panel 1, the dielectric substrate 2, the bottom metal panel 3 and the metal tube 4 are all arranged in the same rectangular coordinate system; wherein:

[0024] The top metal panel 1 is a rectangle, with the center of the short side of the rectangle as the origin, the long side direction as the X axis, the short side direction as the Y axis, and the Z axis perpendicular to the rectangle as the Z axis to establish a rectangular coordinate system; the top metal panel 1 is divided into the first quadrant and the fourth quadrant by the rectangular coordinate system; the top metal panel 1 is provided with a middle straight line formed by a plurality of through holes as edges and a symmetrical area 11 formed by Y-shaped connection at both ends, and a narrow array 12 composed of a plurality of gaps of different lengths is provided in the middle of the symmetrical area 11; and a gradient slit 14 is opened inwardly at the upper part of the Y-shaped at both ends of the symmetrical area 11;

[0025] The dielectric substrate 2 is rectangular and has the same length and width as the top metal panel 1. A symmetrical area 21 is provided on the dielectric substrate 2, which has the same size and shape as the top metal panel 1 and is formed by a straight line in the middle formed by a plurality of through holes and two ends connected in a Y shape.

[0026] The bottom metal panel 3 is rectangular and has the same length and width as the dielectric substrate 2; the bottom metal panel 3 is provided with a symmetrical area 31 having a straight line in the middle formed by a plurality of through holes and connected in a Y shape at both ends, which is the same size and shape as the top metal panel 1; a narrow array 32 having the same size and shape as the top metal panel 1 and composed of a plurality of slits of different lengths is provided in the middle of the symmetrical area 31; an isosceles triangular slot 33 is provided on the Y-shape at both ends of the symmetrical area 32;

[0027] There are several metal tubes 4, which penetrate through the through holes forming the symmetrical area edges on the dielectric substrate 2, and are respectively inserted into the through holes forming the symmetrical area edges on the top metal panel 1 and the bottom metal panel 3, so as to bond the top metal panel 1, the dielectric substrate 2 and the bottom metal panel 3 together;

[0028] The top metal panel 1 has two symmetrical ends with test fixing holes 13 ; the dielectric substrate 2 has two symmetrical ends with test fixing holes 22 ; the bottom metal panel 3 has two symmetrical ends with test fixing holes 34 .

[0029] The narrow array is an impedance modulation area; the lower part of the Y-shape at both ends is a feeding coplanar waveguide, and the upper part of the Y-shape between the anti-modulation area and the feeding coplanar waveguide is a transition structure.

[0030] Example

[0031] The antenna of this embodiment includes a top metal panel 1, a dielectric substrate 2, a bottom metal panel 3 and a metal tube 4. The antenna can be divided into two parts: one is the antenna feeding part composed of a coplanar waveguide and a transition structure, i.e., a Y-shaped structure at both ends of the antenna; the other is the impedance modulation area on the surface of the dielectric integrated waveguide.

[0032] The antenna feed part adopts a coplanar waveguide-transition structure. At the connection between the coplanar waveguide and the dielectric integrated waveguide, a trapezoidal transition structure is adopted to reduce the reflection of electromagnetic waves during the waveguide transition. The height of the trapezoidal transition structure is c = 10.00mm, and the bottom of the trapezoid, i.e., the upper opening of the Y-shape, is Scy = 6.50mm; in order to improve the mode matching degree of the electromagnetic wave in the waveguide, an isosceles triangle slot 33 is provided at the transition structure;

[0033] There are four gradient slots at both ends of the long and narrow array 12, with heights of h1 = 1.0 mm, h2 = 1.5 mm, h3 = 2.0 mm, and h4 = 2.5 mm. The setting of gradient slots is conducive to the matching of coplanar waveguides and dielectric integrated waveguides, and can effectively reduce the side lobes of antenna radiation. The middle part is 265 four-period sinusoidal impedance modulated slots, which can excite high-order harmonics of electromagnetic waves transmitted thereon and realize the outward radiation of four beams.

[0034] The impedance value distribution in the impedance modulation area can be calculated using the following formula.

[0035] The formula for sinusoidal impedance modulation is:

[0036]

[0037] Formula (1) is the theoretical single-beam sinusoidal impedance modulation formula. i is the modulation coefficient corresponding to the sine modulation function, which is used to adjust the energy ratio of each beam. s is the average surface impedance, M is the modulation factor, d i is the modulation period.

[0038] Then, the parameter values ​​in (1) are calculated by formula (2) and the beam radiation direction is determined.

[0039]

[0040] In formula (2), θ is the radiation angle of the beam, d is the modulation period, k0 is the wave vector of the electromagnetic wave in free space, and β0 is the intermediate parameter used to solve X s Here we take θ = -30°, k0 = 628 (30 GHz), and d = 3.2 mm, from which we can find that β0 = 1649.5.

[0041] According to formula (3), the impedance of a single gap is calculated as

[0042]

[0043] Let k x =β0, find X s =2.43.

[0044] The modulation factor M=0.4 is taken, thus determining the sinusoidal impedance modulation function of the single beam.

[0045] According to the multi-beam sinusoidal impedance modulation theory, by adding the single-beam sinusoidal modulation functions in four different directions, a four-beam sinusoidal modulation function is obtained:

[0046]

[0047] Here, in order to realize radiation in four different directions, d1=3.2mm, d2=3.01mm, d3=3.47mm, d4=3.81mm, and a1=a2=a3=a4=0.25 are taken respectively.

[0048] Finally, through electromagnetic simulation analysis of the dispersion diagram of the unit slot structure, the unit slot length and the impedance value represented by it are obtained. Referring to the four-beam sinusoidal impedance theoretical formula (4), periodic slots are opened on the dielectric integrated waveguide to realize four-period sinusoidal impedance modulation on the substrate integrated waveguide.

[0049] Through the above implementation process, a four-beam leaky-wave antenna with a total length of L=148.20 mm, a width of W=25.00 mm, and a thickness of T=1.5 mm is finally obtained.

[0050] After testing, the results are as follows: Figure 5 When the frequency changes from 27.9GHz to 29.1GHz, there are four beams for electromagnetic wave scanning in space, where the scanning angles of each beam are: the first beam can achieve beam scanning from -63° to -30°, the second beam can achieve beam scanning from -39° to -16°, the third beam can achieve beam scanning from -20° to -2°, and the fourth beam can achieve beam scanning from -3° to 17°. After superposition, a total scanning range of 80° can be achieved. The gain of each beam is above 5dB, and it has the ability of side-shooting.

Claims

1. A four-beam frequency scanning leaky wave antenna, characterized in that: It comprises a top metal panel (1), a dielectric substrate (2), a bottom metal panel (3) and a metal tube (4), wherein the top metal panel (1), the dielectric substrate (2), the bottom metal panel (3) and the metal tube (4) are all arranged in the same rectangular coordinate system; wherein: The top metal panel (1) is a rectangle, with the center of the short side of the rectangle as the origin, the long side direction as the X axis, the short side direction as the Y axis, and the Z axis perpendicular to the rectangle as the Z axis to establish a rectangular coordinate system; the top metal panel (1) is divided into a first quadrant and a fourth quadrant by the rectangular coordinate system; a symmetrical area (11) is provided on the top metal panel (1) with a middle straight line formed by a plurality of through holes as edges and two ends connected in a Y shape, and a top narrow array (12) composed of a plurality of gaps of different lengths is provided in the middle of the symmetrical area (11); and a gradient slit (14) is opened inwardly at the upper part of the Y shape at both ends of the symmetrical area (11); The dielectric substrate (2) is rectangular and has the same length and width as the top metal panel (1); a symmetrical area (21) having a straight line in the middle formed by a plurality of through holes and two ends connected in a Y shape and having the same size and shape as the top metal panel (1) is provided on the dielectric substrate (2); The bottom metal panel (3) is rectangular and has the same length and width as the dielectric substrate (2); the bottom metal panel (3) is provided with a symmetrical region (31) having a straight line in the middle formed by a plurality of through holes and connected in a Y-shape at both ends, which is the same size and shape as the top metal panel (1); a bottom narrow array (32) having the same size and shape as the top metal panel (1) and consisting of a plurality of slits of different lengths is provided in the middle of the symmetrical region (31); and an isosceles triangle slot (33) is provided on the Y-shape at both ends of the symmetrical region (31); The metal tubes (4) are in multiple numbers and penetrate through the through holes on the dielectric substrate (2) forming the edges of the symmetrical region (21), and are respectively inserted into the through holes on the top metal panel (1) and the bottom metal panel (3) forming the edges of the symmetrical region, so as to bond the top metal panel (1), the dielectric substrate (2) and the bottom metal panel (3) together; The top metal panel (1) is symmetrically provided with top test fixing holes (13) at both ends; the dielectric substrate (2) is symmetrically provided with substrate test fixing holes (22) at both ends; and the bottom metal panel (3) is symmetrically provided with bottom test fixing holes (34) at both ends. The narrow array is an impedance modulation area; the lower part of the Y-shape at both ends is a feeding coplanar waveguide, and the upper part of the Y-shape between the anti-modulation area and the feeding coplanar waveguide is a transition structure.

2. The four-beam frequency scanning leaky wave antenna according to claim 1, characterized in that: The dielectric substrate is made of Rojers Ro4003C high-frequency material plate, and the top metal panel and the bottom metal panel are made of metal copper plates.

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