+ / -45-degree dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain

Abstract

The invention provides a + / -45-degree dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain, relates to the technical field of microwave communication, and solves the problems that in the prior art, a single-beam leaky-wave antenna is limited in coverage range; the technical problems that the beams of various multi-beam leaky-wave antennas are not on the same surface, the beam gain is influenced by a substrate, the beam direction deviates from the antenna axis, the size is large due to cascade connection, and the gain fluctuation between the harmonics of the double-harmonic leaky-wave antenna is large are solved. According to the technical scheme, a metal elliptical waveguide is adopted as a basic structure of the waveguide leaky-wave antenna, so that the loss is reduced, the power capacity is improved, and meanwhile, the problem of internal field rotation is avoided due to the asymmetric circumferential structure of the ellipse; + / -45-degree polarized dual beams improve the radiation range and the signal strength of the antenna, and expand the original polarization diversity while reducing the signal loss as much as possible, thereby expanding the space channel capacity; according to the invention, two harmonics can be generated, and the gain and stability of the harmonics can be improved.

Description

Technical Field

[0001] The present invention relates to the field of microwave communication technology, and particularly to a ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain. Background Art

[0002] In recent years, information technology has developed rapidly, and intelligent devices have played an increasingly important role in people's lives. As an important bridge for realizing communication between different devices, antennas play a crucial role. Leaky-wave antennas have been favored because of their simple structure, convenient manufacturing, and the absence of a complex feeding network, and thus have been widely used in many fields such as mobile communication, radar technology, and satellite communication. Especially in enclosed spaces, leaky-wave antennas can provide uniform and stable signal coverage, making them very suitable for applications in environments such as railway tunnels and mines.

[0003] Currently, various types of leaky-wave antennas have been proposed, including substrate integrated waveguide, microstrip line, leaky coaxial cable, and metal waveguide, etc. Leaky-wave antennas based on substrate integrated waveguide and microstrip line are widely used because of their lightweight design and easy integration with planar circuits, but their power capacity is limited and the loss is high, so they are not suitable for long-distance wireless communication. Leaky coaxial cable is a traditional leaky-wave antenna, commonly used in tunnel communication, but with the advent of 5G communication and the increase in frequency, its attenuation problem has become more significant. Leaky-wave antennas based on metal waveguide have the characteristics of high power capacity and low loss. Waveguides are mainly divided into three categories: rectangular waveguide, circular waveguide, and elliptical waveguide. Compared with rectangular waveguide, elliptical waveguide is easier to transport and install, and has lower attenuation. In addition, the asymmetric structure of the elliptical waveguide avoids the field rotation problem existing in the circular waveguide, thus improving the radiation performance.

[0004] Multi-beam leaky-wave antennas provide the ability to communicate simultaneously in multiple directions, thereby enhancing communication coverage and realizing the ability to detect multiple targets. Various methods have been developed to achieve the multi-beam function. Substrate integrated waveguide leaky-wave antennas with a double-sided leaky structure usually generate dual beams on the front and back sides of the antenna rather than on one side. Artificial surface plasmon polariton leaky-wave antennas arrange different-sized unit structures on both sides of the substrate, but due to the presence of the substrate between the two unit structures, there is a significant gain difference between the upper and lower beams. Microstrip leaky-wave antennas using higher-order modes generate dual beams that deviate from the antenna axis and face two side surfaces rather than the front of the antenna. Cascade antennas connecting single-beam leaky structures through a feeding network significantly increase the size. In contrast, using two different high-order harmonic leaky-wave antennas provides a more compact solution, which uses the same cells to achieve dual-beam radiation. However, dual-harmonic beam leaky-wave antennas often face challenges in maintaining the gain stability between the two harmonics, resulting in a reduction in the operating bandwidth and signal coverage range.

[0005] With the increasing demand for higher data rates and the widespread application of multiple-input multiple-output systems, multi-polarized antennas have received extensive attention because they can provide higher channel capacity, enhanced robustness, and reduced signal loss. The ±45° polarized leaky-wave antenna can achieve dual polarization through symmetry, ensuring almost the same operating bandwidth, signal coverage, and realized gain between two orthogonal polarized antennas. There has been no research report on the elliptical waveguide leaky-wave antenna with ±45° dual polarization and dual beams. Summary of the Invention

[0006] Therefore, the present invention solves the technical problems existing in the prior art that most of the leaky-wave antennas containing dielectrics have increased losses at high frequencies and insufficient power capacity; the traditional rectangular waveguide leaky-wave antenna is not convenient for transportation and installation due to its size, and the circular waveguide leaky-wave antenna has field rotation, affecting the radiation effect; in addition, most of the existing single-beam leaky-wave antennas have limited coverage; the dual beams generated by the double-sided leaky-wave structure are on the front and back sides rather than on the same surface; the dual beams generated by the leaky-wave antenna with an artificial surface plasmon dual-element structure have an obvious gain difference; the dual beams of the high-order mode leaky-wave antenna are not on the antenna axis but inclined to both sides; the feeding cascaded leaky-wave antenna significantly increases the size of the antenna; moreover, the gain fluctuation amplitude between the two harmonic beams of the existing broadband dual-beam elliptical waveguide leaky-wave antenna is large, and there is no ±45° polarized dual-beam elliptical waveguide leaky-wave antenna. The present invention provides a ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain. The antenna consists of an aluminum elliptical waveguide with slots of a specific shape inclined at ±45° on the surface for radiating ±45° polarized waves. The metal elliptical waveguide is used as the basic structure of the waveguide leaky-wave antenna to reduce losses and improve power capacity. At the same time, the circumferential asymmetric structure of the ellipse avoids the problem of internal field rotation. The ±45° polarized dual beams improve the radiation range and signal strength of the antenna, and expand the original polarization diversity while minimizing signal loss, thereby expanding the spatial channel capacity. A novel slot structure is designed to suppress the stopband to expand the bandwidth, and the gain of the two harmonic beams is improved through further slot design, making the gain of the beams stable throughout the bandwidth. The design is fed coaxially, completely eliminating the need for complex feeding and power splitting networks, and can achieve wide-angle signal coverage without fusing with other antennas, providing an effective wide-angle signal coverage method that includes both forward and backward radiation.

[0007] A ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain provided by the present invention includes: an aluminum metal elliptical waveguide tube, metal structures are arranged at both ends of the aluminum metal elliptical waveguide tube, and an antenna fixing bracket is arranged on the metal structures; through holes are arranged inside the metal structures, and both ends of the aluminum metal elliptical waveguide tube are located inside the through holes.

[0008] Further, there are two sets of the aluminum metal elliptical waveguides, one above the other. A 45° polarization leakage slot is formed on the upper aluminum metal elliptical waveguide, and a mirror-symmetrical -45° polarization leakage slot is formed on the lower aluminum metal elliptical waveguide.

[0009] Further, the aluminum metal elliptical waveguide includes a metal outer wall, a waveguide feed port, and a copper cylindrical transition structure connecting to the SMA coaxial line.

[0010] Further, the 45° polarization leakage slot includes a left folding slot, a middle straight slot, a right folding slot, and a short straight slot.

[0011] Further, the -45° polarization leakage slot and the 45° polarization leakage slot are mirror-symmetrical along the center horizontal line of the two sets of aluminum metal elliptical waveguides.

[0012] Further, there are seven sets of both the -45° polarization leakage slots and the 45° polarization leakage slots.

[0013] Further, the spacing between each set of -45° polarization leakage slots and the spacing between each set of 45° polarization leakage slots are equal.

[0014] The present invention has the following advantages compared with the prior art:

[0015] 1. The ±45° dual-polarization dual-beam elliptical waveguide leaky wave antenna with stable gain provided by the present invention combines a metal elliptical waveguide, an elliptical waveguide feed transition port, and a leaky waveguide unit structure formed by four different lengths and sizes of slots, achieving an operating bandwidth of 4.15 - 6 GHz. The radiation ability of two harmonic beams of a single antenna is formed through the periodic leakage slot units, and the 0th and -1st harmonic beams radiate forward and backward respectively, expanding the signal coverage range while having the beam scanning ability with frequency. The leaky waveguide unit structure proposed by the present invention has the ability to generate two harmonics and respectively improve the magnitude and stability of their respective gains.

[0016] 2. The ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain provided by the present invention, the dimensions of the metal elliptical waveguide and the elliptical waveguide feeding transition port determine the operating bandwidth and the overall frame structure of the leaky-wave antenna. Seven identical slot unit structures are periodically opened on the surface of the metal elliptical waveguide to generate dual-harmonic beams with the same polarization direction and frequency scanning ability. The slot unit structure consists of 4 inclined slots with different lengths, shapes, and the same inclination angle. Among them, the left-folded slot and the right-folded slot are combined to generate dual harmonics, and provide a radiation pattern of the 0th harmonic with stable gain, and form an open stopband suppression structure to broaden the antenna operating bandwidth; the short straight slot and the medium straight slot are added to the structure to improve the gain fluctuation of the -1st harmonic and form a stable radiation pattern. The dual-harmonic beam elliptical waveguide leaky-wave antenna in the other polarization direction is formed by mirror symmetry. The two leaky-wave antennas are placed in parallel and fed separately to form a ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain.

[0017] 3. The ±45° dual-polarized dual-beam elliptical waveguide leaky-wave antenna with stable gain provided by the present invention can simultaneously cover communication frequency bands such as 5G n79, WLAN / WiFi (IEEE 802.11a, b, g, n, ac, ax), but is not limited to these frequency bands. This design technology can also be applied to other frequency bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the aluminum metal elliptical waveguide structure of the present invention;

[0021] Figure 3 It is the antenna transmission response diagram of the present invention;

[0022] Figure 4 It is the antenna radiation response diagram of the present invention with the leakage slot hole as structure 4;

[0023] Figure 5 It is the normalized radiation pattern of the antenna of the present invention;

[0024] Figure 6 It is the change situation of the transmission response of the antenna of the present invention under four leakage slot hole structures;

[0025] Figure 7 These are the diagrams showing the changes of the leakage slot hole structure 1 to 4 of the present invention;

[0026] Figure 8 This is the antenna radiation response diagram of the leakage slot hole with structure 1 of the present invention;

[0027] Figure 9 This is the antenna radiation response diagram of the leakage slot hole with structure 2 of the present invention;

[0028] Figure 10 This is the antenna radiation response diagram of the leakage slot hole with structure 3 of the present invention;

[0029] Explanation of reference numerals:

[0030] 1. Antenna fixing bracket; 2. Metal structure; 3. Through hole; 4. Aluminum metal elliptical waveguide; 5. 45° polarization leakage slot hole; 6. -45° polarization leakage slot hole; 4-1. Outer wall of the elliptical waveguide metal; 4-2. Waveguide feeding port; 4-3. Copper cylindrical transition structure; 5-1. Left folding slot; 5-2. Middle straight slot; 5-3. Right folding slot; 5-4. Short straight slot. Detailed implementation manners

[0031] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] Embodiment 1

[0034] Figure 1 This is the overall structural schematic diagram of the ±45° dual-polarization dual-beam elliptical waveguide leaky wave antenna with stable gain provided in this embodiment, and its structure is as Figures 1 to 2 shown: Low dielectric constant (relative dielectric constant ε rThe antenna fixing bracket of the photosensitive resin 3D printing material 9400-A (n = 3.4), the metal structure 2 for installing and fixing the aluminum metal elliptical waveguide, the through hole 3 for SMA coaxial feeding opened in the metal structure, two aluminum metal elliptical waveguides 4 of the same size, the fixing period 5 opened on the upper waveguide, a total of 7 groups of 45° polarization leaky slot holes, and the mirror-symmetrical -45° polarization leaky slot holes 6 opened on the lower waveguide. The aluminum metal elliptical waveguide 4 has a specially designed structure, including the elliptical waveguide metal outer wall 4-1 with specific structural dimensions, the waveguide feeding port 4-2, and the copper cylindrical transition structure 4-3 connecting the SMA coaxial line. Figure 1 In it, the resin material is represented by light yellow, the aluminum metal material is represented by silver, the air is represented by blue, the copper is represented by orange-red, and the nylon material inside the SMA coaxial line is represented by dark yellow. As Figure 2 shown, the waveguide feeding port 4-2 is arranged inside the aluminum metal elliptical waveguide 4 and is represented by a perspective view in the figure. The actual rectangular slotting structure does not exist. The 45° polarization leaky slot hole 5 has a specially designed structure, including the left folding slot 5-1, the middle straight slot 5-2, the right folding slot 5-3, and the short straight slot 5-4. The -45° polarization leaky slot hole 6 has a mirror-symmetrical design with the same size as the 45° polarization leaky slot hole 5. When the present invention realizes the operation in part of the 5G communication frequency band (5G n79) and part of the WLAN / WiFi (IEEE 802.11a, b, g, n, ac, ax) frequency band, it provides excellent characteristics of dual polarization with a stable gain coverage of four beams and beam scanning, which has great practical value.

[0035] Between the metal structures 2 is the overall structure of the elliptical waveguide leaky wave antenna proposed by the present invention. First, the radio frequency excitation signal is sent out by the SMA coaxial line and fed into the elliptical waveguide 4 through the copper cylindrical transition structure 4-3, forming a transmission mode inside the waveguide and outputting an external load through the copper cylindrical transition structure 4-3 at the other end. Taking 45° polarization as an example, the slot units periodically opened on the surface of the elliptical waveguide 4 cut the surface current of the waveguide outer wall, forming a leakage wave at the slots and radiating outward. The overall 45° inclined slots generate a 45° linearly polarized radiation wave. After passing through a total of 7 groups of leakage slot unit structures fixed and periodically arranged along the elliptical waveguide surface, a dual-beam radiation field with two fast-wave harmonics of the 0th and -1st orders is formed within the working frequency band. In the slot unit, the left folded slot 5-1 and the right folded slot 5-3 are placed at a distance of half a period length to suppress the generated open stopband problem and form a stable radiation of the 0th harmonic beam. The short straight slot 5-4 and the middle straight slot 5-2 are added in sequence to improve and stabilize the gain of the -1st harmonic beam. Thus, a dual-beam elliptical waveguide leaky wave antenna with a 45° polarization direction is formed. The -45° polarization slot unit is mirror-symmetric from the 45° polarization slot unit structure. Two elliptical waveguide leaky wave antennas are placed in parallel, fed separately, and jointly form an elliptical waveguide leaky wave antenna with a total of four beams in the ±45° polarization directions. The present invention can achieve dual-polarization multi-beam radiation in the communication frequency bands (5G n79, WLAN / WiFi (IEEE 802.11a, b, g, n, ac, ax)), and the beam gain fluctuation is small, having the effect of stable radiation.

[0036] Embodiment 2

[0037] In this embodiment, the HFSS simulation software is used for simulation;

[0038] The specific antenna structure dimensions are shown in the following table:

[0039] Table 1: Parameter table of the antenna structure

[0040] Name <![CDATA[l long > <![CDATA[l1]]> <![CDATA[l2]]> <![CDATA[l3]]> <![CDATA[w1]]> <![CDATA[w2]]> <![CDATA[w3]]> <![CDATA[d1]]> <![CDATA[d2]]> <![CDATA[d3]]> <![CDATA[d4]]> P Dimensions (mm) 472 55 20 40 2 4.5 2 15 12.25 2.5 10 51 Name <![CDATA[h1]]> <![CDATA[h2]]> <![CDATA[h3]]> <![CDATA[l d > r <![CDATA[w wall > a b <![CDATA[d dual > Dimensions (mm) 9.46 5 3.93 11.88 3.44 3 51.4 22.1 24.3

[0041] Its antenna structure is as Figures 1 to 2 shown. The transmission response of the antenna is as Figure 3 shown, and the radiation response is as Figure 4 shown, with |S 11With the criteria of |≤ -10 dB and gain fluctuation ≤ 3 dB, it has achieved above 4.15 - 6 GHz (relative bandwidth > 36.45%), which well covers communication frequency bands such as 5G n79, WLAN / WiFi (IEEE 802.11a, b, g, n, ac, ax), etc. Within the bandwidth coverage range, the maximum gain generated after the excitation of this antenna is above 12.6 dBi, and the gain fluctuation ranges of the dual - harmonic beams are ≤ 3 dB and ≤ 1.7 dB respectively. Within the working frequency band, the scanning range of the 0 - th harmonic is +99° to +147° (48°), and the scanning range of the -1 - st harmonic is +37° to +59° (22°), as Figure 5 shown. The leaky slots have four structural shapes from Structure 1 to Structure 4 as Figure 7 shown. In the four cases of having a left - folding slot 5 - 1; having a left - folding slot 5 - 1 and a right - folding slot 5 - 3; having a left - folding slot 5 - 1, a right - folding slot 5 - 3 and a short straight slot 5 - 4; having a left - folding slot 5 - 1, a right - folding slot 5 - 3, a short straight slot 5 - 4 and a middle straight slot 5 - 2, the transmission responses of the antenna are as Figure 6 shown, where Figure 7 Structure 4 in Figures 8 - 10 is the final design. The radiation responses are as Figure 7 shown. The changes in the structure diagrams are as Figure 8 shown. Figure 9 shown. Figure 10 shown. Figure 4 respectively represent the curves of the beam peak gain varying with frequency generated by using Structure 1, 2, 3, 4 in the leaky - wave antenna as Figure 7 shown. Among them, the red curves representing the 0 - th harmonic gain in the 4 figures have higher gains, and the gain fluctuation within the frequency band is ≤ 3 dB. The blue curves represent the gain of the -1 - st harmonic, and the improvement of the gain fluctuation is obvious. Among them, Figure 8 the Structure 1 represented has large gain fluctuations and does not have the ability to suppress OSB; Figure 9 the Structure 2 represented has the ability to suppress OSB, but the gain fluctuation of the -1 - st harmonic is large; Figure 10 the Structure 3 represented has improved the gain of the -1 - st harmonic in the high - frequency part on the basis of Structure 2, and the lowest point has increased by 3 dB; Figure 4 the Structure 4 represented is the final design, with the gain of the -1 - st harmonic improved and stabilized, and the fluctuation within the full frequency band is ≤ 1.7 dB.

[0042] Figure 6 are the transmission response curves of applying Structure 1 - 4 in the leaky - wave antenna respectively. Among them, the curve of Structure 1 is greater than -10 dB in the range of 4.4 - 4.7 GHz, indicating that it does not have the ability to suppress OSB; the curves of Structure 2, 3, 4 are all < -10 dB, indicating that they have the ability to suppress OSB, ensuring the integrity of the bandwidth and not being affected negatively by the stop - band.

[0043] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A ±45° dual-polarized dual-beam elliptical waveguide leaky wave antenna with stable gain, characterized in that, Comprising: An aluminum metal elliptical waveguide (4), with metal structures (2) provided at both ends of the aluminum metal elliptical waveguide (4), and an antenna fixing bracket (1) provided on the metal structure (2); a through hole (3) is provided inside the metal structure (2), and both ends of the aluminum metal elliptical waveguide (4) are located inside the through hole (3).

2. The ±45° dual-polarization dual-beam elliptical waveguide leaky wave antenna with stable gain according to claim 1, characterized in that, There are a total of two sets of the aluminum metal elliptical waveguides (4) arranged vertically. A 45° polarization leakage slot hole (5) is provided on the upper aluminum metal elliptical waveguide (4), and a mirror-symmetrical -45° polarization leakage slot hole (6) is provided on the lower aluminum metal elliptical waveguide (4).

3. The gain-stable ±45° dual-polarization dual-beam elliptical waveguide leaky-wave antenna according to claim 2, characterized in that, The aluminum metal elliptical waveguide (4) includes a metal outer wall (4-1), a waveguide feeding port (4-2), and a copper cylindrical transition structure (4-3) for connecting the SMA coaxial cable.

4. The gain-stable ±45° dual-polarization dual-beam elliptical waveguide leaky-wave antenna according to claim 3, characterized in that, The 45° polarization leakage slot hole (5) includes a left folding slot (5-1), a middle straight slot (5-2), a right folding slot (5-3), and a short straight slot (5-4).

5. The gain-stable ±45° dual-polarization dual-beam elliptical waveguide leaky-wave antenna according to claim 4, characterized in that, The -45° polarization leakage slot hole (6) and the 45° polarization leakage slot hole (5) are mirror-symmetrical along the center horizontal line of the two sets of aluminum metal elliptical waveguides (4).

6. The ±45° dual-polarized dual-beam elliptical waveguide leaky wave antenna with stable gain according to claim 5, characterized in that, Both the -45° polarization leakage slot hole (6) and the 45° polarization leakage slot hole (5) are each provided with seven sets.

7. The gain-stable ±45° dual-polarized dual-beam elliptical waveguide leaky wave antenna according to claim 6, characterized in that, The spacing between each set of -45° polarization leakage slot holes (6) and the spacing between each set of 45° polarization leakage slot holes (5) are equal.

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