Circularly polarized antenna for satellite communication

Abstract

The invention discloses a circularly polarized leaky-wave antenna for satellite communication, and belongs to the technical field of microwave antenna engineering. The leaky-wave antenna solves the problem of wave beam squint existing in an existing leaky-wave antenna. An interdigital capacitor is introduced through an interdigital structure, a corresponding microstrip line below the interdigital structure is designed into a bent line structure, a distributed inductor is introduced, and the interdigital capacitor, the bent line inductor and an equivalent radiation resistor of the antenna jointly form a circuit with a negative group delay characteristic. Furthermore, circularly polarized radiation is realized through orthogonal synthesis of a horizontal polarized radiation component provided by the bent microstrip line and a vertical polarized radiation component provided by the metal rectangular patch containing the interdigital structure. According to the invention, the negative group time delay circuit and the circularly polarized radiation structure unit are ingeniously combined, so that the leaky-wave antenna formed by the structure unit can keep a fixed wave beam direction in a broadband and realize broadband circularly polarized wave beam fixation at a non-dome angle in a Ku frequency band, and the problem of wave beam squint of the circularly polarized leaky-wave antenna is effectively solved.

Description

Technical Field

[0001] The invention relates to a circular polarization leaky wave antenna for satellite communication, belonging to the technical field of microwave antenna engineering. Background Art

[0002] Antennas are key components in wireless communication systems, which can realize the conversion between high-frequency currents in transceivers and electromagnetic waves in free space. Faced with increasingly lightweight wireless communication application scenarios such as satellite communications and 5G / 6G mobile communications, antennas need to meet higher performance requirements, such as simpler feeding networks, smaller antenna size, higher radiation efficiency, and specific polarization modes. As a traveling wave array antenna, leaky wave antennas have the characteristics of simple feeding structure, small size, and high radiation efficiency, and are particularly suitable for satellite communications and 5G / 6G mobile communications.

[0003] The leaky wave antenna itself has the phenomenon that the beam pointing shifts with frequency (beam squint), which makes it difficult for the leaky wave antenna to achieve point-to-point high-speed communication. In order to overcome this problem and make the leaky wave antenna fully applied in wireless point-to-point communication and broadband high-capacity communication systems, people usually use phase compensation methods such as loaded dispersion prisms, Huygens metasurfaces or delay lines to achieve the fixed beam pointing of the leaky wave antenna. However, the existing methods are only applicable to linearly polarized leaky wave antennas, and do not involve the beam fixation of circularly polarized leaky wave antennas, and there are problems such as complex antenna structure, large size, and high cost. Compared with linearly polarized leaky wave antennas, circularly polarized leaky wave antennas can effectively reduce the transmission efficiency loss caused by polarization mismatch during communication and suppress multipath interference, thereby improving the stability and reliability of the channel link. Therefore, there is an urgent need for a satellite communication array antenna with circular polarization characteristics and a simple feeding structure. Summary of the invention

[0004] Aiming at the beam squint problem existing in the existing circularly polarized leaky-wave antenna, the present invention provides a circularly polarized fixed-beam leaky-wave antenna for satellite communication with a simple feeding structure.

[0005] The technical solution of the present invention:

[0006] One of the purposes of the present invention is to provide a circularly polarized fixed beam leaky wave antenna for satellite communication with a simple feeding structure, which is specifically composed of an upper metal layer, an intermediate dielectric plate and a lower metal layer stacked together;

[0007] The upper metal layer is etched from a metal rectangular patch and consists of n radiation units periodically arranged along the length direction;

[0008] The radiation unit is an inverted T-shaped structure, consisting of an upper rectangle including a finger structure and a lower rectangle including a bending line structure; the upper rectangle is located above the middle of the lower rectangle.

[0009] It is further defined that the length of the upper rectangle is Wstub and the width is Lstub.

[0010] It is further defined that the interdigitated finger structure is located in the upper middle position of the upper rectangle, the finger width is s1, the finger gap is g1, and the finger length is l1; below the interdigitated finger structure is a hollow rectangular structure with a length of Ws.

[0011] It is further defined that the length of the lower rectangle is P and the width is Wm.

[0012] It is further defined that the line width of the bending line structure is s2, the bending angle is 90°, the bending width is g2, and the bending height is l2.

[0013] It is further defined that the upper metal layer and the lower metal layer are made of copper.

[0014] Further limiting, 0.04λ g ≤h≤0.15λ g , 0.5λ g ≤Wstub≤1.0λ g , 0.1λ g ≤Lstub≤0.5λ g , 1mm≤Wm≤0.3λ g , 0.5λ g ≤p≤1.5λ g , 0.1λ g ≤Ws≤0.5λ g , 0.1mm≤l1≤0.2λ g , 0.1mm≤l2≤0.2λ g , 0.1mm≤g1≤0.05λ g , 0.1mm≤g2≤0.05λ g , 0.1mm≤s1≤0.05λ g , 0.1mm≤s2≤0.05λ g ,λ g is the waveguide wavelength corresponding to the transmission line.

[0015] Further definition, Wstub is 10mm, Lstub is 4.0mm, Wm is 2.3mm, p is 14mm, Ws is 6.0mm, l1 is 1.8mm, l2 is 2.1mm, g1 is 0.34mm, g2 is 0.57mm, s1 is 0.38mm, and s2 is 0.61mm.

[0016] It is further defined that the length of the upper metal layer, the middle dielectric plate and the lower metal layer is L and the width is W.

[0017] Further defined, L is 112 mm and W is 26 mm.

[0018] It is further defined that the intermediate dielectric plate is made of Rogers RO5880, with a relative dielectric constant of 2.2, a loss tangent of 0.0008, and a thickness of 1.5 mm.

[0019] Beneficial effects:

[0020] The present invention introduces interdigital capacitance by etching staggered slots on a metal rectangular patch to form an interdigital structure, and at the same time designs the corresponding microstrip line below the metal rectangular patch as a meander line structure, thereby introducing distributed inductance, and utilizing the interdigital capacitance, meander line inductance and the equivalent radiation resistance of the antenna to form a parallel RLC resonant circuit, which has a negative group delay characteristic. Further, circular polarization radiation is achieved by orthogonal synthesis of the horizontal polarization radiation component provided by the meandering microstrip line and the vertical polarization radiation component provided by the metal rectangular patch containing the interdigital structure. The present invention cleverly combines the negative group delay circuit with the circular polarization radiation unit, and by selecting appropriate structural parameters, the structure can achieve a phase response characteristic opposite to that of the microstrip transmission line in a wide frequency band, thereby enabling the leaky wave antenna composed of the structural unit to maintain a fixed beam pointing in a wide frequency band, thereby realizing a fixed beam leaky wave antenna with circular polarization characteristics. Working in the Ku band, broadband circularly polarized beam fixing at a non-dome angle can be achieved, effectively solving the beam squint problem of the circularly polarized leaky wave antenna. In addition, the antenna provided by the present invention has a simple structure and has the characteristics of low profile, high efficiency and good left-hand circularly polarized radiation. It is easy to integrate in practical applications, has low production cost, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A top view of the circularly polarized fixed-beam leaky-wave antenna provided in Example 1;

[0022] Figure 2 is a schematic diagram of the structure of the radiation unit;

[0023] Figure 3 Simulation results of reflection coefficient and transmission coefficient of the circularly polarized fixed-beam leaky-wave antenna provided in Example 1;

[0024] Figure 4 The normalized radiation pattern simulation results of the circularly polarized fixed-beam leaky-wave antenna provided in Example 1 at different frequencies in the xoz plane;

[0025] Figure 5 The simulation results of the main beam pointing angle and the axial ratio of the circularly polarized fixed-beam leaky-wave antenna provided in Example 1 within the working frequency band. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0028] Embodiment 1:

[0029] This embodiment provides a circularly polarized fixed-beam leaky-wave antenna operating in the Ku band.

[0030] The antenna unit is made on a Rogers RO5880 dielectric substrate with a relative dielectric constant of 2.2, a loss tangent of 0.0008, and a thickness of 1.5mm. The bottom of the dielectric substrate is a 35um thick copper layer as a reference ground, and the top of the dielectric substrate is a 35um thick copper metal radiation layer with a specific pattern for radiation and electromagnetic control. Figure 1 and Figure 2 As shown, the metal layer on the top of the dielectric substrate is etched with a metal rectangular patch and consists of 8 radiation units arranged periodically along the length direction; the radiation unit is an inverted T-shaped structure, consisting of an upper rectangle containing a forked finger structure and a lower rectangle containing a bending line structure. The upper rectangle is located above the middle of the lower rectangle, and the length Wstub of the upper rectangle is 10mm and the width Lstub is 4.0mm. The forked finger structure is located in the upper middle position of the upper rectangle, the finger width s1 is 0.38mm, the finger gap g1 is 0.34mm, and the finger length l1 is 1.8mm; the number of fingers is 5. Below the forked finger structure is a hollow rectangular structure with a length Ws of 6.0mm. In this way, the interdigital capacitance is introduced by utilizing the staggered slots of the forked finger structure.

[0031] The length P of the lower rectangle is 14mm, and the width Wm is 2.3mm. The line width s2 of the meander line structure is 0.61mm, the bending angle is 90°, the bending width g2 is 0.57mm, the bending height l2 is 2.1mm, and Ls is 3mm. In this way, the lower rectangle is used as a microstrip transmission line, and the microstrip transmission line at the corresponding position of the upper rectangle is replaced by a meander line structure, thereby introducing a distributed inductor, and the cross-toe capacitance, the meander line inductance and the equivalent radiation resistance of the antenna together form a parallel RLC resonant circuit with a negative group delay characteristic.

[0032] In the actual operation of the antenna, the left port 1 is used as the feed excitation port, and the right port 2 is connected to the matching load. The established antenna model is subjected to full-wave electromagnetic simulation analysis, and the simulation results of the reflection coefficient and transmission coefficient are shown in Figure 3 As shown by Figure 3 It can be seen that the reflection coefficient in the wide frequency band of 14GHz to 16GHz is less than -10dB, and the transmission coefficient is less than -30dB. The simulation results of the normalized radiation pattern of the xoz plane at different frequencies are as follows: Figure 4 As shown by Figure 4 It can be seen that within the range of 14.0 GHz to 15.2 GHz, the main beam pointing angle of the antenna is fixed between 10° and 12°, and the angle fluctuation range is only 2°. The simulation results of the main beam pointing angle and the axial ratio within the working frequency band are shown in Figure 2. Figure 5 As shown by Figure 5 It can be seen that the simulated axial ratio of the antenna in the range of 14.0GHz to 14.9GHz is less than 3dB, and it has good circular polarization radiation characteristics. The above results prove that the provided antenna works in the Ku band and can achieve broadband circular polarization beam fixation at non-dome angles, effectively solving the problem of leaky wave antenna beam squint.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circularly polarized leaky wave antenna for satellite communication, characterized in that: It is composed of an upper metal layer, an intermediate dielectric plate and a lower metal layer; The upper metal layer is etched from a metal rectangular patch and consists of n radiation units periodically arranged along the length direction; The radiation unit is an inverted T-shaped structure, consisting of an upper rectangle including a finger structure and a lower rectangle including a bending line structure; the upper rectangle is located above the middle of the lower rectangle.

2. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The length of the upper rectangle is Wstub and the width is Lstub.

3. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The interdigitated finger structure is located in the upper middle position of the upper rectangle, with a finger width of s1, a finger gap of g1, and a finger length of l1; below the interdigitated finger structure is a hollow rectangular structure with a length of Ws.

4. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The length of the lower rectangle is P and the width is Wm.

5. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The line width of the bending line structure is s2, the bending angle is 90°, the bending width is g2, and the bending height is l2.

6. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The upper metal layer and the lower metal layer are made of copper.

7. The circularly polarized leaky-wave antenna for satellite communication according to any one of claims 1 to 6, characterized in that: 0.04λ g 0.15λ ≥ h ≥ 0.04λ g ,0.5λ g 1.0λ ≥ Wstub ≥ 0.5λ g ,0.1λ g 0.5λ ≥ Lstub ≥ 0.1λ g ,0.3λ ≥ Wm ≥ 1 mm g ,0.5λ g 1.5λ ≥ p ≥ 0.5λ g ,0.1λ g 0.5λ ≥ Ws ≥ 0.1 mm g， 0.2λ ≥ l1 ≥ 0.1 mm g ,0.2λ ≥ l2 ≥ 0.1 mm g ,0.05λ ≥ g1 ≥ 0.1 mm g ,0.05λ ≥ g2 ≥ 0.1 mm g ,0.05λ ≥ s1 ≥ 0.1 mm g ,0.05λ ≥ s2 ≥ 0.1 mm g ,λ g is the waveguide wavelength corresponding to the transmission line.

8. The circularly polarized leaky wave antenna for satellite communication according to claim 1, characterized in that: The length of the upper metal layer, the middle dielectric plate and the lower metal layer is L, and the width is W.

9. The circularly polarized leaky-wave antenna for satellite communication according to claim 8, characterized in that: L is 112mm and W is 26mm.

10. The circularly polarized leaky wave antenna for satellite communication according to claim 8, characterized in that: The intermediate dielectric board uses Rogers RO5880, with a relative dielectric constant of 2.2, a loss tangent of 0.0008, and a thickness of 1.5 mm.

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