A high-gain dual-circularly polarized end-fire antenna array based on a full-metal parallel plate structure

Abstract

The application relates to a high-gain dual-circularly-polarized end-fire antenna array based on a full-metal parallel plate structure, which adopts a full-metal parallel plate waveguide as a main transmission line and is composed of upper and lower metal copper plates with air filling therebetween. Horizontal radiation units are a periodic loading horizontal dipole array, and vertical radiation units are a vertical dipole array and are arranged orthogonally. By periodically introducing the dipole units, series feed excitation is realized to form end-fire radiation. Based on the symmetric structure design, when one end of the two ports of the transmission line is excited and the other end is connected with a matching load, the leaky-wave radiation of the traveling wave type can be realized. By introducing orthogonal resonant units, 90-degree phase difference is generated to realize dual-circularly-polarized end-fire radiation. The antenna array has the advantages of high gain, low cost, simple structure, easy processing and batch production and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wireless and communication technology, and particularly relates to a high-gain dual-circularly-polarized end-fire antenna array of parallel-plate transmission line series-fed periodic loaded resonant units composed of a full-metal structure. BACKGROUND

[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 the radar blind area problem, and improve the detection performance. At the same time, end-fire high-gain antennas are essential equipment in satellite communication systems, which can receive and send satellite signals and provide global communication services, whether it is mobile communication, Internet access, or satellite television, remote monitoring, end-fire high-gain antennas play a key role.

[0003] Traditional end-fire antennas include Yagi antennas, logarithmic-periodic antennas, etc. When electromagnetic waves propagate along the traveling wave structure, continuous radiation can be generated, and the radiated wave is called a leak wave. This structure that generates a leak wave is called a leaky-wave antenna. Leaky-wave antennas inherit the wideband characteristics of traveling wave antennas and have the characteristic of main lobe beam scanning with frequency. Further, when the phase shift constant is controlled, the radiation direction can be controlled to form a leaky-wave end-fire radiation, which has strong directivity and high gain characteristics, improving the signal transmission efficiency and anti-interference ability. In recent years, end-fire leaky-wave technology based on periodic loading perturbation resonant units of transmission waveguide structure has developed rapidly. However, the reports on end-fire circularly-polarized antennas have significantly decreased, especially the design of antennas with dual-circularly-polarized end-fire radiation performance is slightly scarce. In addition, the existing reported end-fire antenna structures are generally complex and have high processing costs, which is not conducive to mass production. SUMMARY

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

[0005] The specific technical solutions of the present application are as follows:

[0006] A high-gain dual-circularly polarized end-fire antenna array based on a full-metal parallel plate structure adopts a full-metal parallel plate waveguide as a main transmission line, and is composed of the following structures: a parallel plate waveguide composed of upper and lower metal copper plates, with air filled therebetween, horizontal radiation elements being a horizontal dipole array periodically loaded on both sides of the parallel plate waveguide, with a quarter-wavelength spacing between the elements, vertical radiation elements being a shared vertical dipole array, which is orthogonally arranged with the horizontal elements, with an eighth-wavelength spacing between the elements, the upper and lower metal copper plates being mechanically fixed by a medium fixing piece which has no influence on electromagnetic properties, and the two ports being symmetrically distributed and connected with an SMA coaxial feeding interface and a 50Ω matching load respectively.

[0007] All the horizontal dipole elements are of the same size, and all the vertical dipole elements are of the same size.

[0008] The horizontal dipole array is on one side of a single-layer metal copper plate, and the upper and lower metal copper plates are on different sides.

[0009] The vertical radiation elements are in a tilted parallel array of the parallel plate waveguide.

[0010] The thickness of the metal copper plate is 0.5 mm.

[0011] The medium fixing piece is a screw and a nut made of polytetrafluoroethylene.

[0012] The technical scheme of the present application has the following beneficial effects:

[0013] The present application selects a parallel plate transmission line as a main structure, periodically introduces dipole elements, enables serial feed excitation from parallel line coupling energy, adjusts the element size and spacing, and forms end-fire radiation. Based on the symmetric structure design, any one end of the transmission line is excited, and the other end is connected with a matching load, so that the traveling wave type leaky wave radiation can be realized. Therefore, by introducing an orthogonal resonant element, the element structure makes the lead and lag generated from the two-port feeding energy with a 90° phase difference, so that the dual-circularly polarized end-fire radiation of the shared orthogonal resonant element structure is generated, that is, the dual-circularly polarized wave can be realized. The dual-circularly polarized antenna can realize the free switching of left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) by adjusting the excitation and matching of the two ports.

[0014] The present application couples and serially feeds the resonant elements periodically loaded based on the full-metal parallel plate structure, realizes a high-gain tightly coupled shared element dual-circularly polarized end-fire antenna array. The orthogonal radiation of the horizontal dipole and the shared tightly coupled vertical dipole forms the end-fire circular polarization; the excitation and matching load of the two ports realize the free switching of the left and right rotation directions of the end-fire circularly polarized antenna. Based on the fact that the phase constant of the air-filled parallel plate end-fire antenna is approximately equal to the propagation constant, the end-fire high-gain radiation is stable, the structure is simple, the cost is low, and the processing and batch production are convenient. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the high-gain dual circularly polarized end-fire antenna array based on a full-metal parallel plate structure according to the present application.

[0016] Figure 2 is a top view of the high-gain dual circularly polarized end-fire antenna array based on a full-metal parallel plate structure according to the present application.

[0017] Figure 3 is a left view of the high-gain dual circularly polarized end-fire antenna array based on a full-metal parallel plate structure according to the present application.

[0018] Figure 4 is a right view of the high-gain dual circularly polarized end-fire antenna array based on a full-metal parallel plate structure according to the present application.

[0019] Figure 5 is the simulation and measurement S parameter curves of the high-gain dual circularly polarized end-fire antenna array under the condition of exciting two ports respectively.

[0020] Figure 6 is the measured and simulated axial ratio and gain curves of the high-gain dual circularly polarized end-fire antenna array under the condition of exciting two ports respectively.

[0021] Figure 7 is the simulation and measurement far-field patterns of the high-gain dual circularly polarized end-fire antenna array under the condition of feeding from port one and applying a load to port two; 4.6 GHz, 4.8 GHz, and 5 GHz respectively.

[0022] Figure 8 is the simulation and measurement far-field patterns of the high-gain dual circularly polarized end-fire antenna array under the condition of feeding from port two and applying a load to port one; 4.6 GHz, 4.8 GHz, and 5 GHz respectively.

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

[0024] The present application will be described in detail below in conjunction with the drawings and specific embodiments.

[0025] In order to illustrate the advantages of the present application, the present application will be described in detail in conjunction with specific embodiments. Note that the embodiments are only used to illustrate the implementation and do not limit the scope of the present application.

[0026] The principle of the inventive antenna will be explained in detail below in conjunction with the drawings.

[0027] The application discloses a high-gain dual-circularly-polarized end-fire antenna array generated by a full-metal parallel transmission structure series-fed orthogonal resonant dipole unit.

[0028] As shown in Figure 1 , Figure 2 , the application provides a full-metal dual-circularly-polarized end-fire antenna, which is a parallel double-conductor series-fed periodic resonant unit structure and has two ports, one of which is connected with an SMA coaxial excitation and the other of which is connected with a 50Ω matching load.

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

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

[0031] The horizontal dipole units have the same spacing, which is one-quarter wavelength, and the vertical dipole units have the same spacing, which is one-eighth wavelength.

[0032] The antenna is composed of pure metal copper plates, and the two ends are connected with SMA interfaces and radio frequency coaxial lines.

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

[0034] The full-metal antenna has a bidirectional port, and the antenna is divided into two layers, each of which is composed of a periodic horizontal perturbation array structure and a vertical shared tightly coupled array, and the two array structures are orthogonal in space, and the orthogonal phase difference and amplitude difference are controlled by the left-right stagger of the horizontal perturbation structure and the rotation of the tightly coupled shared array by a certain angle, so that the end-fire circularly-polarized radiation is formed in the far field. The far-field electric field can be qualitatively represented as

[0035] (1)

[0036] wherein, 、 are the amplitude ratio and phase difference of the two orthogonal polarization components respectively, and the axial ratio can be defined as:

[0037] (2)

[0038] Therefore, by reasonably controlling the structure state of the two orthogonal dipole resonant units, the axial ratio performance can be adjusted to be the lowest, and circularly polarized radiation waves are generated.

[0039] The air-filled parallel plate sandwich is used as a waveguide transmission line, one end of which is connected with a coaxial SMA to transmit energy to the resonant units on both sides and above and below, and the other end is connected with a 50Ω matching load. The left and right rotation directions can be freely switched by interchanging the positions of the SMA and the matching load. Along the direction of the transmission line, a pair of array units are loaded periodically, the unit spacing is adjusted, different modes of spatial harmonics are excited, and the radiation direction can be calculated using the following formula:

[0040] (3)

[0041] (4)

[0042] The control unit spacing is such that the excited spatial harmonic works in the fundamental mode ( n =0), so the pure metal structure is easy to realize the propagation constant close to the phase shift constant, and then form an end-fire radiation.

[0043] The two dielectric screws and nuts are made of polytetrafluoroethylene composite material, as shown in Figure 1 The relative dielectric constant is 2.1, which is used to fix the upper and lower antenna structures and has the effect of supporting connection, and the effect is similar to that of an air-filled parallel plate waveguide structure. Figure 3 、 Figure 4 The left view and the right view of the antenna are shown in Figures 1 and 2, respectively. Due to the consistency and central symmetry of the upper and lower parts of the antenna, when excitation and matching loads are applied at port one and port two, respectively, left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) can be obtained.

[0044] The design of the high-gain dual-circularly-polarized end-fire antenna array based on the air-filled parallel plate structure includes the following steps:

[0045] (1) Determine the center frequency;

[0046] (2) Select a parallel plate waveguide structure as the main transmission series feed source;

[0047] (3) Introduce a periodic orthogonal perturbation structure to couple the waveguide edge field energy for excitation;

[0048] (4) According to the spatial harmonic theory, reasonably design the resonant unit spacing and excite the fundamental mode harmonic field of the periodic resonant unit;

[0049] (5) Reasonably arrange and adjust the structure state of the orthogonal perturbation resonant unit, so that the two wave field components in the far field are equal in amplitude and differ by 90°, forming an end-fire circularly polarized radiation wave;

[0050] (6) Based on the symmetry of parallel plate structure, the vertical dipole array unit is introduced as a shared orthogonal resonant structure of two-port horizontal dipoles to realize double circular polarization;

[0051] (7) Processing and experimental testing: according to the simulation design based on antenna theory support, and compared with the experimental results - S parameter, pattern, gain and other far field results.

[0052] Figure 5 The S parameter results of the antenna of the application under the excitation of two ports respectively are given, and it can be seen that the simulation S parameters of two ports are basically consistent, which is due to the central symmetric structure of the antenna of the application, so that the wave field path can be realized between the ports of the parallel transmission line structure. The results show that the S 11 and S 12 of the two ports are below -10dB, indicating good radiation, and the measurement and simulation results are basically consistent, and the slight difference is mainly due to the processing error and interface welding process.

[0053] Figure 6 The measured and simulated axial ratio and gain curves of the antenna of the application under the excitation of two ports respectively are given. 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 achieved at 4.8GHz in the frequency band. Figure 7 and Figure 8 are the far field patterns of left and right circularly polarized wave field under the excitation of two ports respectively. It can be seen that stable end-fire effect can be achieved in the frequency band under two circular polarization modes, and the cross polarization level at the center frequency is as high as 30dB or more, which has good circular polarization performance.

[0054] The double circularly polarized end-fire antenna of the application has high gain and low cost, and can be mass-produced; the superior circular polarization performance has strong anti-interference ability, and the polarization utilization rate is high, the left and right rotation can be freely switched, and it is very suitable for long distance wireless communication system 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: The main transmission line is a parallel plate waveguide made of all metal plates. The structure is as follows: a parallel plate waveguide (4) is made of two layers of metal copper plates with air filling between them. The 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. The vertical radiation unit is a vertical dipole (1) array orthogonal 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 piece (6) that has no effect on the electromagnetic performance. Port 1 (2) and Port 2 (5) are symmetrically distributed and connected to the SMA coaxial feed interface and the 50Ω matching load, respectively. The horizontal dipole (3) array is on one side of a single-layer copper plate, and the upper and lower copper plates are on different sides. The vertical radiation unit is arranged in a tilted parallel array on the parallel plate waveguide (4); The vertical dipole (1) is in a single row.

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 thickness of the copper plate is 0.5 mm.

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

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