A wide-beam dipole antenna array with low mutual coupling

Abstract

The present invention discloses a wide-beam dipole antenna array with low mutual coupling, comprising: a metal ground, a half-wave symmetric oscillator array arranged in a linear interval parallel to the metal ground, and in the array additional structure, a long stub is respectively arranged at the middle of two adjacent half-wave symmetric oscillators and at both ends of the array, and the long stub is vertically connected to the metal ground; a group of short stubs is correspondingly arranged below each half-wave symmetric oscillator, and each group of short stubs has four and is vertically connected to the metal ground, and the four short stubs are distributed in pairs at both ends of the half-wave symmetric oscillator and are located on the upper and lower sides of the linear arrangement direction. The present invention utilizes the even-mode impedance adjustment effect of the middle stub of the dipole and the beam broadening effect of the overall additional structure on the E plane H plane to synchronously achieve low mutual coupling between units and beam broadening of the units, and can take into account the adaptability of the decoupling level, decoupling bandwidth and matching bandwidth, profile height, structural complexity, low cost and stability of the in-band beam width.

Description

Technical Field

[0001] The present invention relates to a microwave communication device, and particularly to a wide-beam dipole antenna array. Background Art

[0002] Dipole antennas are widely used in radio communication, broadcasting, television, satellite communication and other fields because of their simplicity, economy and ease of fabrication. When multiple dipoles form an antenna array, if there is strong mutual coupling between each antenna element, problems such as deterioration of active matching, distortion of the radiation pattern, and decrease in radiation efficiency will occur. A dipole antenna with low mutual coupling can effectively solve the problems caused by strong mutual coupling, thereby optimizing the overall performance. At the same time, in phased array applications, the half-power beam width is also an important index that has been widely concerned. A wide-beam dipole antenna with low mutual coupling can increase the scanning range and is suitable for related applications that require wide-angle scanning. At the same time, the low mutual coupling between units can ensure good performance. Therefore, a wide-beam dipole antenna with low mutual coupling has good engineering application value.

[0003] Existing dipole antennas cannot simultaneously meet the requirements of low mutual coupling between units and wide-beam radiation of the units, and can only achieve decoupling or wide-beam radiation between dipole antennas separately. Among them, there are mainly three methods for decoupling dipole antennas: the first is to load open-loop resonators vertically placed on the four sides of the dipole element to suppress the space wave between the units and achieve decoupling. However, the mutual coupling zero point is located outside the band, resulting in limited reduction of in-band mutual coupling; the second is to add two layers of planar decoupling structures above the dipole to introduce reflected waves to form in-phase cancellation with the original coupling signal. However, the profile increases greatly, and the decoupling bandwidth cannot cover the working bandwidth; the third is to combine multiple parasitic resonance structures with the dipole to generate multiple coupling zero points to achieve broadband decoupling. However, there are problems such as complex structure and high cost. The main methods for realizing wide-beam radiation of dipoles are mainly two: the first is to vertically extend the metal downward at both ends of the dipole to introduce a vertical current component to broaden the beam width, but this will cause a large fluctuation of the in-band beam width; the second is to place a row of parallel metal columns directly below both ends of the dipole, and introduce a vertical current component through the strong coupling with the dipole to broaden the beam. This method can effectively achieve beam broadening within the frequency band. The above-mentioned decoupling methods or beam broadening methods of dipoles can only achieve a single target and cannot simultaneously meet the requirements of low mutual coupling and wide-beam performance. Summary of the Invention

[0004] Object of the Invention: Aiming at the above-mentioned existing technologies, a wide-beam dipole antenna array with low mutual coupling is proposed, which simultaneously meets the requirements of low mutual coupling and wide beam.

[0005] Technical solution: A wide-beam dipole antenna array with low mutual coupling, comprising: a metal ground, a half-wave symmetric dipole array arranged linearly and spaced parallel to the metal ground, and an array additional structure; the array additional structure includes long stubs and short stubs; a long stub is arranged at the middle of two adjacent half-wave symmetric dipoles and at both ends of the half-wave symmetric dipole array, and the long stub is vertically connected to the metal ground; a group of short stubs is correspondingly arranged below each half-wave symmetric dipole, each group of short stubs has four, all of which are vertically connected to the metal ground, and the four short stubs are distributed in pairs at both ends of the half-wave symmetric dipole and are located on the upper and lower sides in the linear arrangement direction.

[0006] Further, the height of the long stub is between 0.16λ0 - 0.20λ0, and the spacing between adjacent long stubs is between 0.46λ0 - 0.50λ0.

[0007] Further, the heights of the short stubs are the same, all between 0.12λ0 - 0.16λ0; in each group of short stubs, the distance between the two short stubs in the polarization direction is between 0.40λ0 - 0.44λ0, and the distance between the two short stubs perpendicular to the polarization direction is between 0.08λ0 - 0.12λ0.

[0008] Further, the two arms of the half-wave symmetric dipole are arranged in a straight line, the planar shape of a single arm is trapezoidal, and the shorter bottom sides of the two trapezoids are located at the center feed point of the half-wave symmetric dipole.

[0009] Further, the height of the half-wave symmetric dipole is set between 0.24λ0 and 0.25λ0, and the spacing between two adjacent half-wave symmetric dipoles is set between 0.5λ0 and 0.6λ0.

[0010] Beneficial effects: Existing dipole antennas cannot simultaneously meet the requirements of low mutual coupling between elements and wide-beam radiation, and there are also problems such as low decoupling level, decoupling bandwidth unable to cover the working bandwidth, high profile, complex structure and high cost, or large fluctuations in the in-band beam width. Taking a 1×2 dipole antenna array as an example, the present invention uses three long stubs and two groups of short stubs as the additional structure of the dipole array, utilizes the even-mode impedance adjustment effect of the middle stub between two dipoles, and the beam broadening effect of the out-of-phase and in-phase currents of the overall additional structure on the E plane H plane to simultaneously achieve low mutual coupling between elements and beam broadening of the elements, and can also take into account the adaptability of the decoupling level, decoupling bandwidth and matching bandwidth, profile height, structural complexity, low cost, and stability of the in-band beam width.

[0011] Specifically, three long branches are perpendicularly connected to the metal ground and are respectively located in the middle and at both ends of the two half-wave dipoles. The middle long branch can adjust the even-mode impedance of the antenna array to approach the differential-mode impedance, thereby significantly reducing the mutual coupling between elements within a certain frequency band. At the same time, the long branches at both ends of each dipole can generate out-of-phase vertical currents, greatly increasing the beam width of the element E plane.

[0012] There are four short branches in each of the two groups of short branches. They are all perpendicularly connected to the metal ground and are symmetrically distributed in pairs at both ends below the dipole. By coupling each group of short branches with their respective dipoles, on the one hand, out-of-phase currents are generated in the polarization direction and in-phase currents are generated in the vertical polarization direction, thereby broadening E plane, H plane beam width. On the other hand, the short branches in the middle of the two dipoles can also change the even-mode impedance to a certain extent, thus promoting the decoupling between dipole elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a three-dimensional structural schematic diagram of the low-mutual-coupling wide-beam dipole antenna of the present invention;

[0014] Figure 2 is a comparison of the parameter simulation results before and after adding an additional structure in the embodiment of the present invention S ;

[0015] Figure 3 is a comparison of the half-power beam width simulation results before and after adding an additional structure in the embodiment of the present invention;

[0016] Figure 4 is the simulated radiation pattern of the embodiment of the present invention at 3.8 GHz. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention will be further explained below with reference to the accompanying drawings.

[0018] As Figure 1 shown, a low-mutual-coupling wide-beam dipole antenna array is composed of a half-wave symmetrical dipole 1, a long branch 2, a short branch 3, and a metal ground 4. Among them, the two arms of the half-wave symmetrical dipole are arranged in a straight line, the planar shape of a single arm is trapezoidal, and the shorter bottom sides of the two trapezoids are located at the center feeding point of the half-wave symmetrical dipole. Each half-wave symmetrical dipole 1 is arranged parallel to the metal ground 4 and is arranged in a linear interval.

[0019] Take as Figure 1Taking the 1×2 array shown as an example for illustration, the array structure is symmetric about the central symmetry plane on the left and right. The heights of the two half-wave symmetric oscillators 1 are set between 0.24λ0 and 0.25λ0, arranged in a linear interval, and the spacing is set between 0.5λ0 and 0.6λ0, where λ0 is the free space wavelength corresponding to the central frequency. When considering the terminal effect of the antenna, the actual length of the half-wave symmetric oscillator is less than the theoretical length.

[0020] Three long stubs 2 are vertically connected to the metal ground 4, located in the middle and at both ends of the two half-wave symmetric oscillators respectively, and are on the same vertical plane as the half-wave symmetric oscillator 1. The height of the long stub 2 is between 0.16λ0 - 0.20λ0, and the spacing between adjacent long stubs 2 is between 0.46λ0 - 0.50λ0.

[0021] Each half-wave symmetric oscillator 1 is correspondingly provided with a set of short stubs 3. The number of short stubs 3 in each set is four, all vertically connected to the metal ground 4, and the heights of the short stubs 3 are the same, all between 0.12λ0 - 0.16λ0. In each set, the four short stubs 3 are symmetrically distributed in pairs at both ends of the half-wave symmetric oscillator 1, and are symmetrically located on the upper and lower sides of the linear arrangement direction in pairs. The distance between the two short stubs 3 in the polarization direction is between 0.40λ0 - 0.44λ0, and the distance between the two short stubs 3 perpendicular to the polarization direction is between 0.08λ0 - 0.12λ0.

[0022] In the above 1×2 array structure, the three long stubs 2 and the two sets of short stubs 3 form an additional structure of the 1×2 dipole array. The signal is excited from the central feeding point of each half-wave symmetric oscillator 1. Under the overall action of the half-wave symmetric oscillator array and the additional structure, wide-beam radiation of the unit and low mutual coupling between units are realized.

[0023] In this process, since the long stub 2 in the middle of the array structure is located on the central symmetry plane of the two half-wave symmetric oscillators 1, when the symmetry plane is equivalent to an electric wall, this long stub is equivalent to not existing. When the symmetry plane is equivalent to a magnetic wall, this long stub generates an effect, making the even-mode impedance of the antenna array approach the differential-mode impedance, and can significantly reduce the mutual coupling between the half-wave symmetric oscillators 1 within a certain frequency band. At the same time, each half-wave symmetric oscillator 1 is coupled with the long stubs 2 at both ends of it, generating out-of-phase currents on the two side long stubs 2, which can increase the E beam width of the unit surface to a large extent.

[0024] On this basis, each set of short stubs 3 can couple signals from their corresponding half-wave symmetric oscillators 1 to generate four vertical currents. Two currents are out-of-phase in the polarization direction, and two currents are in-phase in the perpendicular polarization direction. Therefore, it can further improve the E beam width of the unit surface, and can broaden the HThe beamwidth in the [plane]. At the same time, the four short stubs 3 located in the middle of the two array structures also play a role in changing the even-mode impedance of the antenna array, so they can further promote the decoupling between the two dipoles. Finally, the dipole array can simultaneously obtain E in the [plane] and H beamwidth broadening in the [plane], as well as lower mutual coupling.

[0025] The above 1×2 array can be extended to a 1×n dipole antenna array. The structure of the present invention can simultaneously meet the requirements of low mutual coupling between units and wide-beam radiation of units, and can also take into account the adaptability of the decoupling level, decoupling bandwidth and matching bandwidth, profile height, structural complexity, low cost, and stability of the in-band beamwidth. The antenna size in this embodiment is 0.96λ0× 0.13λ0× 0.23λ0, Figure 2 The simulation results of the parameters of this embodiment are compared with those of the S without additional structure. From Figure 2 it can be seen that the coupling degree between units within the overall working frequency band of the antenna array before decoupling exceeds -12 dB, and it can be lower than -25 dB after decoupling. At the same time, the matching is significantly improved after decoupling. The simulated half-power beamwidths in the [plane] and E in the [plane] before and after adding the additional structure are as shown in H Figure 3 . After decoupling, the beamwidth in the [plane] within the working frequency band can reach 104°~115°, E and the beamwidth in the [plane] can reach 102°~103°. Compared with before decoupling, the beamwidth in the [plane] H increases by more than 50°, and the beamwidth in the [plane] E increases by more than 10°. H The simulated radiation pattern at 3.8 GHz when the antenna is working is shown in Figure 4 . The half-power beamwidth in the [plane] is 110°, and the half-power beamwidth in the [plane] E is 105°. The cross-polarization levels are both good. H

[0026] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.​​

Claims

1. A wide-beam dipole antenna array with low mutual coupling, characterized in that Comprising: A metal ground (4), an array of half-wave symmetric dipoles (1) arranged in a linear and spaced manner parallel to the metal ground (4), and an array additional structure; the array additional structure includes long stubs (2) and short stubs (3); a long stub (2) is provided at the middle of two adjacent half-wave symmetric dipoles (1) and at both ends of the half-wave symmetric dipole array respectively, and the long stub (2) is perpendicularly connected to the metal ground (4); a group of short stubs (3) is correspondingly provided below each half-wave symmetric dipole (1), each group of short stubs (3) has four, all perpendicularly connected to the metal ground (4), and the four short stubs (3) are distributed in pairs at both ends of the half-wave symmetric dipole (1) and are located on the upper and lower sides in the linear arrangement direction. The height of the long stub (2) is between 0.16λ0 - 0.20λ0, and the spacing between adjacent long stubs (2) is between 0.46λ0 - 0.50λ0; the heights of the short stubs (3) are the same, all between 0.12λ0 - 0.16λ0; in each group of short stubs (3), the distance between the two short stubs (3) in the polarization direction is between 0.40λ0 - 0.44λ0, and the distance between the two short stubs (3) perpendicular to the polarization direction is between 0.08λ0 - 0.12λ0; the height of the half-wave symmetric dipole (1) is set between 0.24λ0~0.25λ0, and the spacing between two adjacent half-wave symmetric dipoles (1) is set between 0.5λ0~0.6λ0, where λ0 is the free space wavelength corresponding to the center frequency.

2. The low mutual coupling wide beam dipole antenna array according to claim 1, characterized in that, The two arms of the half-wave symmetric dipole (1) are arranged in a straight line, the planar shape of a single arm is trapezoidal, and the shorter bases of the two trapezoids are located at the center feed of the half-wave symmetric dipole.

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