A wide-beam circularly polarized antenna based on crossed dipoles

Abstract

The application discloses a wide-beam circularly polarized antenna based on a cross dipole, wherein the end of an electric dipole is designed into a T-shaped structure to reduce the size of the antenna; a parasitic patch is introduced to widen the impedance bandwidth and the beam width of the antenna; and the beam is widened and the circular polarization angle range is increased through the method that the vertical monopole pattern is complementary to the cross dipole.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave antennas, and particularly relates to a wide-beam circularly polarized antenna based on crossed dipoles. BACKGROUND

[0002] There are three basic forms to realize the circular polarization (CP) operation of a microstrip antenna: (1) single-feed method; (2) multi-feed method; and (3) multi-element method. The multi-element method uses multiple linearly polarized radiating elements or circularly polarized (CP) radiating elements, and realizes the circular polarization operation of the antenna through a phase sequential spiral array, with each feeding point feeding each radiating element respectively. Bolster first proved the method of obtaining circularly polarized waves using single-feed crossed dipoles in the literature “A new type of circular polarizer using crossed dipoles,” IRE Trans. Microw. Theory Techn., vol. 9, no. 5, pp. 385-388, 1961. It is proved that the CP wave generated by the antenna has the minimum axial ratio point in the AR profile under the condition of correct selection of the length of the dipole. The compact crossed dipole (including a cavity back reflector) is introduced as a simple 3-dB AR beam width widening technology. These antennas are suitable for single-band or multi-band applications with a bandwidth of less than 10%.

[0003] In the literature “X. -y. Pu, Z. -w. Gui and Z. -h. Liu, "Crossed Dipole Antenna with Reflector for Wide-beam and Wideband Circularly Polarized Radiation," in 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2019, pp. 1-3, doi: 10.1109 / ICMMT45702.2019.8992064.”, a crossed dipole antenna with a reflector for wide-beam and wideband circularly polarized radiation is proposed on a RO4003 dielectric substrate, with a radiation patch and a reflector, and CP radiation is excited by loading a phase delay line (phase shift line) at the corner of the sequentially rotated element. The feeding is from the center by a 50-ohm coaxial line, and impedance matching is realized by adjusting the width of the phase shift line. An impedance bandwidth of 1.35-2.15 GHz and a 3dB AR beam width of 165° (-81°~84°) at 1.47 GHz are obtained at the center frequency of 1.472 GHz, and the maximum circularly polarized gain is 5.28dBic.

[0004] The document "H. -J. Zhang and F. -S. Zhang, "Circularly Polarized Crossed Dipole With Magnetoelectric Dipole for Wideband and Broadbeam Applications," in 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC), 2018, pp. 1-3, doi: 10.1109 / CSQRWC.2018.8455610." proposes a single-feed circularly polarized crossed-dipole loaded with a magnetoelectric dipole to improve the beamwidth. The size is 0.58 *0.58 *0. The final implementation effect is that the impedance bandwidth is 72.1% (1.25 GHz~2.66 GHz), the 3dB ARBW bandwidth is 45.3% (1.45 GHz~2.30 GHz). The average gain of the antenna in the CP operating frequency band is 8.1 dBic. The 3dB AR beamwidth is greater than 162° in the range of 1.85-2.25GHz.

[0005] The document "W. J. Yang, Y. M. Pan and S. Y. Zheng, "A Low-Profile Wideband Circularly Polarized Crossed-Dipole Antenna With Wide Axial-Ratio and Gain Beamwidths," IEEE Transactions on Antennas and Propagation, vol. 66, no. 7, pp. 3346-3353, July 2018, doi: 10.1109 / TAP.2018.2829810." proposes a crossed-dipole antenna composed of four trapezoidal patches, and the required phase difference for circular polarization is achieved by connecting the two pairs of crossed dipoles through a quarter-wave phase shift line (3 / 4 circular ring). The low profile of this model is 0.1 The impedance bandwidth and 3-dB AR bandwidth are 78.3% and 63.4%, respectively. Over 120° 3dB ARBW and over 110° HPBW are simultaneously achieved in a wide passband of 50.7%.

[0006] A low-profile wideband circularly polarized crossed-dipole antenna with wide axial-ratio and gain beamwidths, W. J. Yang, Y. M. Pan and S. Y. Zheng, "A Low-Profile Wideband Circularly Polarized Crossed-Dipole Antenna With Wide Axial-Ratio and Gain Beamwidths," in IEEE Transactions on Antennas and Propagation, vol. 66, no. 7, pp. 3346-3353, July 2018, doi: 10.1109 / TAP.2018.2829810.” presents a crossed-dipole antenna loaded with magnetic dipoles, which has a quarter-wavelength phase shift line (1 / 4) circular ring connected and fed, a 2x2 rectangular radiation patch array cut at the diagonal and a metal reflection cavity. The dipole can produce wide-band and wide-beam circularly polarized radiation characteristics, achieve an impedance bandwidth of 1.274-2.360GHz, a 3dB AR bandwidth of 1.39-1.82GHz, and a right-handed circular polarization with a very wide 3dB ARBW ( ) and high radiation efficiency ( ) in the operating frequency band. SUMMARY

[0007] In view of the problems existing in the background art, the purpose of the present application is to overcome the defects of the prior art, and to provide a wide-beam circularly polarized antenna based on a crossed-dipole.

[0008] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0009] A wide-beam circularly polarized antenna based on a crossed-dipole, comprising: a crossed-dipole, four parasitic patches, a rectangular slot, four metal monopoles, a dielectric substrate, a coaxial feed line, and a quarter-wavelength phase shift line.

[0010] The four electric dipole antenna radiation arms are arranged in a "cross" shape, and the ends are in a "T" shape, wherein two adjacent electric dipole antenna radiation arms are arranged on the upper surface of the dielectric substrate, and the other two electric dipole antenna radiation arms are arranged on the lower surface of the dielectric substrate, and the two electric dipole antenna radiation arms on the same surface are connected by a quarter-wavelength phase shift line; the four parasitic patches are arranged on the upper surface of the dielectric substrate, and the distance between the side edge of the parasitic patch and the side edge of the adjacent electric dipole antenna radiation arm is smaller than the distance between the other side edge of the parasitic patch and the side edge of the adjacent electric dipole antenna radiation arm, and the four parasitic patches and the rectangular slots thereon are arranged in a circumferential array between the four electric dipole antenna radiation arms, and the metal monopole is arranged vertically below the parasitic patch and is fixedly connected with the four parasitic patches, and the coaxial feed line is arranged at the center of the antenna for feeding.

[0011] The wide-beam circularly polarized antenna is a left-handed circularly polarized antenna, and on the basis of a right-handed circularly polarized structure, the rectangular slot on the parasitic patch is changed to the other side, so that the distance between the side of the parasitic patch with the rectangular slot and the electric dipole radiation arm is smaller than the distance between the other side, and the two pairs of electric dipoles and the quarter-wavelength phase shift lines connected therewith are mirror-imaged about the xoz plane.

[0012] Further, the electric dipole antenna radiation arm ends in a "T" shape, which prolongs the current path and reduces the transverse size of the antenna.

[0013] Further, the distance between the parasitic patch and the two adjacent electric dipole antenna radiation arms is different, and the distance between the parasitic patch and the electric dipole antenna radiation arm (1) is smaller than the distance between the parasitic patch (5) and the electric dipole antenna radiation arm (2).

[0014] Further, the rectangular slot (9) on the parasitic patch (5) extends inward from the side of the parasitic patch (5) close to the electric dipole antenna radiation arm (1), and the rectangular slot changes the current distribution on the parasitic patch and affects the resonant frequency of the parasitic patch.

[0015] Further, the metal monopole is connected with the parasitic patch and is located on the midline between the two adjacent electric dipole radiation arms, and the metal monopole is fed by electric dipole coupling.

[0016] The mechanism of the application is as follows:

[0017] The application feeds the cross-dipole by coaxial line and quarter wavelength phase shift line, the phase difference of the inner and outer conductors of the coaxial line is 180°; a pair of electric dipole antenna radiation arms on the upper and lower surfaces of the dielectric substrate form an electric dipole antenna, the two groups of electric dipole antennas are perpendicular to each other; the quarter wavelength phase shift line generates a 90° phase difference; therefore, theoretically, the current amplitudes on the four electric dipole antenna radiation arms are equal, and the phases are sequentially different by 90°, so that a circular polarization pattern is generated at a high elevation angle; by changing the end of the electric dipole antenna radiation arm into a T shape, the transverse size of the antenna is reduced.

[0018] By adding a parasitic patch, a new resonance point is formed, the impedance bandwidth of the antenna is widened, and the low-elevation gain of the antenna is increased, and the rectangular slot on the parasitic patch can adjust the resonant frequency; the distance between the parasitic patch (5) and the electric dipole antenna radiation arm (1) is less than the distance between the parasitic patch (5) and the electric dipole antenna radiation arm (2), and the right-handed circular polarization effect is improved;

[0019] The metal monopole is located on the midline of the adjacent electric dipole antenna radiation arm, and is coupled and fed by the electric dipole antenna radiation arm and the parasitic patch, and the phases of the four vertical monopoles are also sequentially different by 90°; by adjusting the position of the metal monopole, the monopole antenna pattern and the electric dipole antenna pattern are complementary to each other at a low elevation angle, forming a circular polarization pattern, and the beam is widened.

[0020] The application has the advantages that:

[0021] The application provides a wide-beam circularly polarized antenna based on a cross-dipole. The application reduces the size of the antenna by designing the end of the electric dipole into a T shape; introduces a parasitic patch to widen the impedance bandwidth of the antenna; and widens the beam by the complementary method of the vertical monopole pattern and the cross-dipole, and increases the angle range of the circularly polarized radiation. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a top view of the antenna structure of the application.

[0023] Figure 2 is a schematic diagram of the overall structure of the antenna of the application.

[0024] Figure 3 is a side view of the antenna structure of the application

[0025] Figure 4 is an antenna reflection coefficient S11 graph in the embodiment of the application.

[0026] Figure 5 is a normalized two-dimensional pattern at the center frequency point of the antenna in the embodiment of the application.

[0027] Figure 6is the axial ratio graph at the center frequency point of the antenna in the embodiment of the application. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments and drawings.

[0029] A wide-beam circularly polarized antenna based on crossed dipoles, a structural schematic diagram of which is shown in Figures 1-3 Specifically, the wide-beam circularly polarized antenna comprises electric dipole antenna radiation arms 1, 2, 3, 4, parasitic patches 5, 6, 7, 8, rectangular slots 9, 10, 11, 12, metal monopoles 14, 15, 16, 17, a dielectric substrate 18, a coaxial feed line 19, and a quarter-wavelength phase shift line 13.

[0030] Figure 1 is a top view of the antenna structure of the present application, Figure 2 is a schematic diagram of the overall structure of the antenna of the present application, Figure 3 is a side view of the antenna structure of the present application. As can be seen from the figure, the coaxial feed line 19 is arranged at the center of the antenna for feeding, and the phase difference between the inner and outer conductors is 180°. The four electric dipole antenna radiation arms 1, 2, 3, 4 are arranged in a "cross" shape, and the ends thereof are in a "T" shape. Two of the electric dipole antenna radiation arms 2, 3 are arranged on the upper surface of the dielectric substrate, and the other two electric dipole antenna radiation arms 1, 4 are arranged on the lower surface of the dielectric substrate 18. The electric dipole antenna radiation arms on the same surface are connected by a quarter-wavelength phase shift line 13 to produce a 90° phase difference. A pair of electric dipole antenna radiation arms on the upper and lower surfaces of the dielectric substrate 18 opposite to each other constitute an electric dipole antenna. The current amplitudes on the four electric dipole antenna radiation arms are equal, and the phases thereof are sequentially different by 90°, so that a circularly polarized pattern is generated at a high elevation angle.

[0031] The four parasitic patches 5, 6, 7, 8 are arranged on the upper surface of the dielectric substrate 18 and located between adjacent electric dipole antenna radiation arms. The parasitic patches 5, 6, 7, 8 can increase the low-elevation-angle gain of the antenna and form new resonant points to increase the impedance bandwidth of the antenna. Rectangular slots 9, 10, 11, 12 are arranged on the parasitic patches 5, 6, 7, 8 to adjust the resonant frequency of the parasitic patches 5, 6, 7, 8. The distance between the parasitic patch 5 and the electric dipole antenna radiation arm 1 is less than the distance between the parasitic patch 5 and the electric dipole antenna radiation arm 2.

[0032] The metal monopole 14 is located on the midline of the adjacent electric dipole antenna radiation arms 1, 2, and is fixedly connected with the parasitic patch 5. The rest of the metal monopoles 15, 16, 17 are the same as the metal monopole 14 through the coupling feed of the electric dipole antenna radiation arm 1 and the parasitic patch 5. The phases of the four metal monopoles 14, 15, 16, 17 are sequentially different by 90°; by adjusting the positions of the metal monopoles 14, 15, 16, 17, the monopole antenna pattern and the electric dipole antenna pattern are complementary to each other at low elevation angles, forming a circularly polarized pattern, and the widening of the beam is realized.

[0033] The wide-beam circularly polarized antenna is a left-handed circularly polarized antenna, and on the basis of a right-handed circularly polarized structure, the rectangular slot on the parasitic patch is changed to the other side, so that the distance from the side of the parasitic patch with the rectangular slot to the dipole radiation arm is less than the distance from the other side, and the two pairs of dipoles and the quarter-wavelength phase shift lines connected thereto are mirror processed about the xoz plane.

[0034] Embodiment one

[0035] In the embodiment, in the wide-beam circularly polarized antenna based on the cross dipole, the total size is 76mm*76mm, the total height is-30mm, the dielectric substrate thickness is 0.508mm, the dielectric substrate uses Rogers RO4003, the relative dielectric constant is 3.55, and the loss angle is cut to 0.0027. The size of the parasitic patch is 13.3mm*13.6mm, the size of the rectangular slot is 8mm*1mm, the inner diameter and the outer diameter of the quarter-wavelength phase shift line are 3.9mm and 4.5mm respectively. The radius of the vertical metal monopole is 1mm, and the length is 30mm. The length of the single dipole antenna radiation arm is 23mm.

[0036] Simulation tests are performed, and the results show that the impedance bandwidth of the antenna with a return loss less than-10dB is 2.43GHz-2.83GHz (as shown in Figure 4 The 3dB_ARBW is 32.5° and the HPBW is 224° when phi=0°, and the 3dB_ARBW is 190° and the HPBW is 232° when phi=90° at the center frequency f0=2.58GHz, as shown in Figure 5 , Figure 6 The axial ratio is 2.47dB when Theta=0° at the center frequency f0=2.58GHz, as shown in Figure 6 ,

[0037] The above only describes the preferred embodiments of the present application, and all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

Claims

1. A wide-beam circularly polarized antenna based on a cross dipole, characterized in that: It includes a dielectric substrate, four electric dipole antenna radiating arms, four parasitic patches, four metal monopoles, a self-phase-shifting feed network, and a coaxial feed line; The wide-beam circularly polarized antenna is a right-hand circularly polarized antenna. The four electric dipole antenna radiating arms of the right-hand circularly polarized antenna are arranged in a cross shape at their beginnings and a T shape at their ends. Two adjacent electric dipole antenna radiating arms are disposed on the upper surface of the dielectric substrate, and the other two electric dipole antenna radiating arms are disposed on the lower surface of the dielectric substrate. Two electric dipole antenna radiating arms located on the same surface are connected by a quarter-wavelength phase-shifting line. The parasitic patch is disposed on the upper surface of the dielectric substrate and located between adjacent electric dipole antenna radiating arms. A rectangular slot is formed on the side of the parasitic patch adjacent to the electric dipole antenna radiating arm, and this side is connected to the adjacent electric dipole antenna... The spacing between the sides of the radiating arms is smaller than the spacing between the other side and the side of the adjacent electric dipole antenna radiating arm. Four parasitic patches and their rectangular slots are arranged in a circular array between the four electric dipole antenna radiating arms. The metal monopoles are vertically arranged below the parasitic patches, and each metal monopole is fixedly connected to a corresponding parasitic patch. One of the metal monopoles is located on the centerline of the adjacent electric dipole antenna radiating arm and is fixedly connected to the parasitic patch. It is fed through the coupling between the electric dipole antenna radiating arm and the parasitic patch. The other metal monopoles are the same. The four metal monopoles are sequentially 90° out of phase. The coaxial feed line is set at the center of the wide-beam circularly polarized antenna for feeding. When the wide-beam circularly polarized antenna is a left-hand circularly polarized antenna, based on the right-hand circularly polarized structure, the rectangular slot on the parasitic patch is moved to the other side, so that the distance between the side of the parasitic patch with the rectangular slot and the dipole radiating arm is smaller than that of the other side. The two pairs of dipoles and the quarter-wavelength phase-shifting line connected to them are mirrored about the xoz plane.

2. A wide-beam circularly polarized antenna based on a cross dipole according to claim 1, characterized in that: The rectangular slot on the parasitic patch extends inward from the side of the parasitic patch closest to the radiating arm of the electric dipole antenna. The rectangular slot changes the current distribution on the parasitic patch and affects the resonant frequency of the parasitic patch.

3. A wide-beam circularly polarized antenna based on a cross dipole according to claim 1, characterized in that: The metal monopole is connected to the parasitic patch and is located on the midline of the radiating arms of two adjacent dipoles. The metal monopole is fed through electric dipole coupling.

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