High-gain dual-circularly-polarized end-on-fire antenna array based on all-metal parallel plate structure

Abstract

The invention relates to a high-gain dual-circularly-polarized end-on-fire antenna array based on an all-metal parallel plate structure, which adopts an all-metal parallel plate waveguide as a main transmission line and consists of an upper layer of metal copper plate and a lower layer of metal copper plate, and air is filled between the upper layer of metal copper plate and the lower layer of metal copper plate. The horizontal radiation unit is a periodically loaded horizontal dipole array, and the vertical radiation unit is a vertical dipole array and is orthogonally arranged. Through periodically introducing the dipole units, series feed excitation is realized, and end-fire radiation is formed. Based on a symmetrical structure design, any one of two ports of the transmission line is excited, and the other end is connected with a matched load to realize traveling wave leaky wave radiation. And an orthogonal resonance unit is introduced, a 90-degree phase difference is generated, and dual-circular-polarization end-fire radiation is realized. The antenna array has the advantages of high gain, low cost, simple structure, convenience in processing and batch production and the like.

Description

Technical Field

[0001] The invention belongs to the field of wireless and communication technology, and specifically relates to a high-gain dual circularly polarized end-fire antenna array composed of a parallel plate transmission line series-fed periodically loaded resonant unit composed of an all-metal structure. Background Art

[0002] End-fire antennas are widely used in military, aviation, navigation, meteorology and other fields due to their narrow beam width and high gain radiation characteristics. For example, in military applications, end-fire antenna arrays can solve the problem of large antenna array aperture, improve radar blind spots, and improve detection performance. At the same time, end-fire high-gain antennas are indispensable equipment in satellite communication systems. They can receive and send satellite signals and provide communication services worldwide. Whether it is mobile phone communications, Internet access, satellite TV, or remote monitoring, end-fire high-gain antennas play a key role.

[0003] Traditional end-fire antennas include Yagi antennas, log-periodic antennas, etc. When electromagnetic waves propagate along the traveling wave structure, they can continuously generate radiation. The radiated waves are called leaky waves, and the structure that generates leaky waves is called a leaky wave antenna. The leaky wave antenna inherits the broadband characteristics of the traveling wave antenna, and has the characteristic that the main lobe beam scans with frequency. Furthermore, when the phase shift constant is controlled, its radiation direction can be controlled to form leaky wave end-fire radiation, which has the characteristics of strong directivity and high gain, and improves the transmission efficiency and anti-interference ability of the signal. In recent years, the end-fire leaky wave technology formed by the periodic loading perturbation resonant unit of the transmission waveguide structure has developed rapidly. However, the reports on end-fire circularly polarized antennas have been greatly reduced, especially the antenna design with dual circularly polarized end-fire radiation performance is slightly scarce. In addition, the existing reported end-fire antenna structures are generally more complicated, the processing cost is high, and it is not conducive to mass production. Summary of the invention

[0004] The purpose of the present invention is to provide a high-gain dual circular polarization end-fire antenna array based on an all-metal parallel plate structure, which solves the problems of limited gain and low polarization utilization in the prior art.

[0005] The specific technical solutions of the present invention are as follows: A high-gain dual circularly polarized end-fire antenna array based on an all-metal parallel plate structure uses an all-metal parallel plate waveguide as the main transmission line. The structure is as follows: a parallel plate waveguide composed of an upper and lower layer of metal copper plates, with air filling in between. The horizontal radiation unit is a horizontal dipole array periodically loaded on both sides of the parallel plate waveguide, with a unit spacing of one-quarter wavelength. The vertical radiation unit is a shared vertical dipole array, which is arranged orthogonally to the horizontal unit, with a unit spacing of one-eighth wavelength. The upper and lower metal copper plates are mechanically fixed by dielectric fixings that have no effect on electromagnetic performance. The dual ports are symmetrically distributed and are respectively connected to the SMA coaxial feeding interface and the 50Ω matching load.

[0006] All horizontal dipole units are the same size, and all vertical dipole units are the same size.

[0007] The horizontal dipole array is on one side of the single-layer metal copper plate, and the upper and lower layers of the metal copper plate are on different sides.

[0008] The vertical radiation units are arranged in a tilted parallel array on a parallel plate waveguide.

[0009] The thickness of the metal copper plate is 0.5 mm.

[0010] The medium fixing parts are screws and nuts made of polytetrafluoroethylene.

[0011] The beneficial effects of the technical solution of the present invention are as follows: The present invention selects parallel plate transmission lines as the main structure, and periodically introduces dipole units to couple energy from parallel lines to achieve series feed excitation, and adjusts the unit size and spacing to form end-fire radiation. Based on the symmetrical structure design, traveling wave leakage wave radiation can be achieved by exciting any one end of the two ports of the transmission line and connecting the other end to a matching load. Therefore, by introducing an orthogonal resonance unit, the unit structure generates different advance and lag with a phase difference of 90° when feeding energy from the two ports, thereby generating dual circularly polarized end-fire radiation that shares an orthogonal resonance unit structure, and realizing dual circularly polarized waves. The dual circularly polarized antenna can achieve free switching between left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) by adjusting the excitation and matching of the two ports.

[0012] The present invention realizes a high-gain tightly coupled shared unit dual circularly polarized end-fire antenna array by coupling series-feeding excitation of the periodically loaded resonant unit based on the all-metal parallel plate structure. End-fire circular polarization is formed by orthogonal radiation of horizontal dipoles and shared tightly coupled vertical dipoles; free switching of left and right rotation directions of the end-fire circularly polarized antenna is realized by alternating excitation and matching loads of dual ports. Based on the phase constant of the air-filled parallel plate end-fire antenna being approximately equal to the propagation constant, the end-fire high-gain radiation stability is realized, and the structure is simple, the cost is low, and it is easy to process and mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the high-gain dual circularly polarized end-fire antenna array based on the all-metal parallel plate structure described in the present invention.

[0014] Figure 2 It is a top view of the high-gain dual circularly polarized end-fire antenna array based on the all-metal parallel plate structure described in the present invention.

[0015] Figure 3 It is a left view of the high-gain dual circularly polarized end-fire antenna array based on the all-metal parallel plate structure described in the present invention.

[0016] Figure 4 It is a right view of the high-gain dual circularly polarized end-fire antenna array based on the all-metal parallel plate structure described in the present invention.

[0017] Figure 5 It is the simulated and measured S-parameter curve of the high-gain dual circularly polarized end-fire antenna array when the two ports are excited separately.

[0018] Figure 6 These are the measured and simulated axial ratio and gain curves of a high-gain dual circularly polarized end-fire antenna array when both ports are excited separately.

[0019] Figure 7 It is a high gain dual circular polarization end-fire antenna array fed from port one and loaded from port two, with simulated and measured far-field patterns; 4.6GHZ, 4.8GHZ, 5GHZ respectively.

[0020] Figure 8 It is a high gain dual circular polarization end-fire antenna array fed from port two and loaded from port one. The simulation and measurement far-field patterns are 4.6GHZ, 4.8GHZ, and 5GHZ respectively.

[0023] In the figure, 1. vertical dipole; 2. port one; 3. horizontal dipole; 4. parallel plate waveguide; 5. port two; 6. dielectric fixture. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] In order to illustrate the advantages of the present invention, the present invention is described in detail in combination with specific implementation methods. Note that the implementation is only used to illustrate the implementation method and does not limit the scope of the present invention.

[0026] The principle of the inventive antenna will be explained in detail below based on the accompanying drawings.

[0027] The present invention specifically discloses a high-gain dual circular polarization end-fire antenna array based on air-filled all-metal parallel transmission structure series-fed orthogonal resonant dipole units. The air-filled parallel plate is used as the main transmission line structure to series-feed a number of periodically loaded dipole array pairs.

[0028] like Figure 1 , Figure 2 As shown, the present invention provides a dual circular polarization end-fire antenna with a full metal structure, whose main body is a parallel dual-conductor series-fed periodic resonant unit structure, with two ports, one end connected to SMA coaxial excitation, and the other end connected to a 50Ω matching load.

[0029] The main body of the present invention is composed of two layers of metal copper plates, one above the other. Horizontal dipole units spaced one quarter wavelength apart are periodically introduced on one side of each metal copper plate. The horizontal dipole units of the two layers of metal copper plates are on different sides. 23 vertical dipole units are placed vertically on the metal copper plates at intervals of one eighth wavelength. The vertical dipole array forms a shared resonant tightly coupled unit, which forms a certain angle with the metal copper plate.

[0030] All horizontal dipole units are the same size, and all vertical dipole units are the same size.

[0031] The horizontal dipoles are spaced the same distance apart, which is one quarter of a wavelength, and the vertical dipoles are spaced the same distance apart, which is one eighth of a wavelength.

[0032] The antenna is made of pure metal copper plate, and its two ends are connected by SMA interface and RF coaxial line.

[0033] The upper and lower double-conductor metal copper plates are fixed by two dielectric bolts and four dielectric nuts, which is equivalent to an air dielectric filled parallel plate transmission structure.

[0034] The all-metal antenna of the present invention has a bidirectional port. The antenna is divided into two layers, each layer consisting of an introduced periodic horizontal perturbation array structure and a vertical shared tightly coupled array. The two array structures are orthogonal to each other in space. The orthogonal phase difference and amplitude difference are controlled by the left-right misalignment of the horizontal perturbation structure and the rotation of the tightly coupled shared array by a certain angle, so that end-fire circularly polarized radiation is formed in the far field. Its far-field electric field can be qualitatively characterized as (1) in, , are the amplitude ratio and phase difference of two orthogonal polarization components respectively. The axial ratio can be defined as: (2) Therefore, by reasonably controlling the structural states of the two orthogonal dipole resonant units, the axial ratio performance can be adjusted to be the lowest and circularly polarized radiation waves can be generated.

[0035] The air-filled parallel plate sandwich is used as a waveguide transmission line. One end is fed with a coaxial SMA to transfer energy to the array resonant units on both sides and above and below, and the other end is connected to a 50Ω matching load. By swapping the positions of the SMA and the matching load, the left and right rotation directions can be switched freely. By periodically loading the array unit pairs along the transmission line and adjusting the unit spacing, spatial harmonics of different modes can be excited. The radiation direction can be calculated using the following formula: (3) (4) The present invention controls the cell spacing so that the excited spatial harmonics work in the fundamental mode ( n =0), so the pure metal structure can easily achieve a propagation constant close to the phase shift constant, thereby forming end-fire radiation.

[0036] The two medium screws and nuts are made of polytetrafluoroethylene composite materials, such as Figure 1 As shown, the relative dielectric constant is 2.1, and its function is to fix the upper and lower antenna structures and has a supporting and connecting function. Its effect is approximately an air-filled parallel plate waveguide structure. Figure 3 , Figure 4 They are the left and right views of the antenna, respectively. Since the upper and lower parts of the antenna have the same structure and are centrally symmetrical, applying excitation and matching loads at port one and port two can obtain left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP), respectively.

[0037] The high-gain dual circular polarization end-fire antenna array design based on the air-filled parallel plate structure of the present invention comprises the following steps: (1) Determine the center frequency; (2) Selecting a parallel plate waveguide structure as the main transmission string feed source; (3) Introducing a periodic orthogonal perturbation structure to couple the waveguide edge field energy for excitation; (4) According to the spatial time-harmonic theory, the spacing between the resonant units is reasonably designed to excite the fundamental mode time-harmonic field of the periodic resonant element; (5) Reasonably arrange and adjust the structural state of the orthogonal perturbation resonant unit so that the two wave field components in the far zone are equal in amplitude and 90° apart, forming an end-fire circularly polarized radiation wave; (6) Based on the symmetry of the parallel plate structure, the vertical dipole array unit is introduced as a shared orthogonal resonant structure of the dual-port horizontal dipole to achieve dual circular polarization; (7) Processing and experimental testing: Perform simulation design based on antenna theory and compare with experimental results - far-field results such as S parameters, radiation pattern, gain, etc.

[0038] Figure 5The S parameter results of the antenna of the present invention when the two ports are excited are given. It can be seen that the simulated S parameters of the two ports are basically consistent. This is because the antenna of the present invention has a central symmetric structure, so the wave field path can be mutually inverted between the ports of the parallel transmission line structure. The results show that the S parameters of the dual ports within the frequency band are 11 and S 12 Both are below -10dB, indicating good radiation. The measurement and simulation results are generally consistent, and the slight differences are mainly caused by processing errors and interface welding processes.

[0039] Figure 6 The measured and simulated axial ratio and gain curves of the antenna of the present invention when the two ports are excited separately are shown in Figure 1. The measured and simulated results are in good agreement, and the lowest axial ratio performance of 0.52dB and the highest end-fire gain of 12.17dBi are obtained at 4.8GHz in the frequency band. Figure 7 and Figure 8 The far-field patterns of left-hand and right-hand circularly polarized wave fields under the excitation of two ports are shown respectively. It can be seen that the two circularly polarized modes can achieve stable end-fire effects within the frequency band, and the cross-polarization level at the center frequency is as high as 30dB or more, which has good circular polarization performance.

[0040] The dual circularly polarized end-fire antenna of the present invention has high gain, low cost and can be mass-produced; the superior circular polarization performance has strong anti-interference ability, and the polarization utilization rate is high, and the free switching between left and right rotation can be realized, which is very suitable for long-distance wireless communication systems and point-to-point information transmission.

Claims

1. A high-gain dual circularly polarized end-fire antenna array based on an all-metal parallel plate structure, characterized in that: An all-metal parallel plate waveguide is used as the main transmission line, and the structure is as follows: a parallel plate waveguide (4) consisting of two layers of metal copper plates, with air filling in between; a horizontal radiation unit is a horizontal dipole (3) array periodically loaded on both sides of the parallel plate waveguide, with a unit spacing of one quarter wavelength; a vertical radiation unit is a vertical dipole (1) array, arranged orthogonally to the horizontal unit, with a unit spacing of one eighth wavelength; the upper and lower metal copper plates are mechanically fixed by a dielectric fixing member (6) that has no effect on electromagnetic performance; port one (2) and port two (5) are symmetrically distributed, and are respectively connected to an SMA coaxial feeding interface and a 50Ω matching load.

2. The high-gain dual circularly polarized end-fire antenna array according to claim 1, characterized in that: All horizontal dipole (3) units are the same size, and all vertical dipole (1) units are the same size.

3. The high-gain dual circularly polarized end-fire antenna array according to claim 1, characterized in that: The horizontal dipole (3) array is on one side of the single-layer metal copper plate, and the upper and lower layers of the metal copper plate are on different sides.

4. The high-gain dual circularly polarized end-fire antenna array according to claim 1, characterized in that: The vertical radiation units are arranged in a tilted parallel array on the parallel plate waveguide (4).

5. The high-gain dual circularly polarized end-fire antenna array according to claim 1, characterized in that: The thickness of the metal copper plate is 0.5 mm.

6. The high-gain dual circularly polarized end-fire antenna array according to claim 1, characterized in that: The medium fixing member (6) is a screw and a nut made of polytetrafluoroethylene.

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