Wide-beam Beidou antenna based on metal strip loading

Abstract

The invention belongs to the field of antennas, and discloses a wide-beam Beidou antenna based on metal strip loading, which comprises a first dielectric plate and a second dielectric plate, a first radiation patch is arranged on the upper surface of the first dielectric plate, a second radiation patch is arranged on the upper surface of the second dielectric plate, metal strips are arranged on the opposite side surfaces of the second dielectric plate respectively, an air layer is arranged between the first dielectric plate and the second dielectric plate, and the first radiation patch and the second radiation patch are connected through a plurality of probes. The first radiation patch is provided with a group of gaps. According to the antenna, wide wave beams are achieved through metal strip loading, multi-frequency coverage is achieved through slot loading, and circular polarization and high gain are achieved through four feed points.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of antennas, in particular to a wide-beam Beidou antenna based on metal strip loading. BACKGROUND

[0002] This part provides only background information related to the present disclosure, which does not necessarily have to be prior art.

[0003] Navigation and positioning in complex environments face significant challenges. In urban environments, high-rise buildings are densely arranged, causing satellite signal paths to be severely blocked, reducing the number of visible satellites and significantly attenuating the signal. The surface reflection of a large number of glass curtain walls and buildings further exacerbates the multipath effect, causing superimposed interference in the received signal. In natural environments such as valleys and hilly areas, the shielding effect of the terrain is also significant. The mountain slope and rock wall can shield part of the satellite signal and cause multipath interference through reflection, resulting in uncertainty in the received signal path and strength. Circularly polarized antennas have the advantages of reducing Faraday effects, suppressing multipath interference, and improving system stability, and are widely used in navigation antennas. Therefore, it is of great significance to expand the antenna axial ratio beam width and operating frequency band, and to improve the circular polarization performance and received signal stability of the Beidou antenna.

[0004] Miniaturization and lightness of the antenna can be achieved by reducing the physical size, but it may lead to a decline in antenna performance (such as gain, directivity, bandwidth), which is not suitable for GNSS signal reception in complex environments. Some relatively simple antennas are usually designed for a specific frequency and can achieve high gain and good performance in a specific frequency band, but as a navigation antenna, it needs to receive signals in multiple frequency bands at the same time, so a single frequency band antenna is not suitable for navigation and positioning in complex environments such as severe signal blocking. In order to improve the positioning accuracy, in the process of pursuing high gain of the antenna, the radiation pattern of the antenna may become more sharp, and high directivity antennas often need more precise control of the radiation direction, but this may lead to a narrow axial ratio beam width, unstable circular polarization performance of the antenna, and a decline in the performance of the received signal.

[0005] The deficiencies of the prior art include:

[0006] Existing small antennas may have a decline in performance (such as gain, directivity, bandwidth) due to size reduction, making it difficult to meet the needs of miniaturization and lightness of antennas for low-altitude unmanned aerial vehicles.

[0007] The existing antenna resonance design is mainly for a single frequency band, and the multi-band performance is not optimized, which cannot cover multiple navigation systems or multiple frequency bands at the same time.

[0008] Existing high-gain antennas often have a narrow radiation pattern and axial ratio beam width, unstable circular polarization performance of the antenna, and a decline in the performance of the received signal. SUMMARY

[0009] In view of the deficiencies of the prior art, the present application provides a wide-beam Beidou antenna based on metal strip loading.

[0010] The wide-beam Beidou antenna based on metal strip loading comprises a first dielectric plate and a second dielectric plate; the upper surface of the first dielectric plate is provided with a first radiation patch, and the upper surface of the second dielectric plate is provided with a second radiation patch; one pair of side surfaces of the second dielectric plate are respectively provided with metal strips; the first dielectric plate and the second dielectric plate are separated by an air layer; the first radiation patch and the second radiation patch are connected by a plurality of probes; and a group of slits are arranged on the first radiation patch.

[0011] Further, the group of slits comprises a group of strip-shaped slits and a group of ring-shaped slits; the group of strip-shaped slits comprises a plurality of strip-shaped slits with the same length extending from the center point of the first radiation patch along the radiation direction, and the included angle between adjacent strip-shaped slits is the same; the group of ring-shaped slits comprises a plurality of ring-shaped slits with the same size as the strip-shaped slits, and one ring-shaped slit is arranged in the area between adjacent two strip-shaped slits; the center of the ring-shaped slit is located on the bisector of the included angle between the adjacent two strip-shaped slits, and the distance from the center of the ring-shaped slit to the center point of the first radiation patch is equal.

[0012] Further, the number of probes is the same as the number of ring-shaped slits; the probes pass through the first dielectric plate and are connected with the first radiation patch; the probes are cylindrical, and the axis of the cylinder passes through the center of the ring-shaped slit.

[0013] Preferably, the number of strip-shaped slits is four.

[0014] Further, the included angle between the extension direction of the strip-shaped slit and the edge of the first radiation patch is 45°.

[0015] Further, the distance from the center of the ring-shaped slit to the center point of the first radiation patch is one fourth of the length of the short side of the first radiation patch.

[0016] Further, the slit width of the strip-shaped slit and the ring-shaped slit is the same.

[0017] Further, the feeding system of the antenna is composed of four probes; the method of sequential rotation feeding is adopted to apply phase shifts of 0°, 90°, 180° and 270° respectively by means of a phase shifter; the feeding points are sequentially rotated by 0°, 90°, 180° and 270° along the center of the array element; and the same amplitude but sequentially delayed 90° excitation signals are injected to realize wideband right-handed circular polarization; and the matching effect is achieved by adjusting the position and distance of the feeding points. The material of the probes is copper.

[0018] Further, the length of the metal strip is the same as the length of the second dielectric plate. The height of the metal strip is the sum of the thicknesses of the first dielectric plate, the second dielectric plate and the air layer. The metal strip can be copper.

[0019] The present application aims at the problem that miniaturization leads to the decline of antenna performance (such as gain, directivity, bandwidth), and loads two symmetrical metal strips on the periphery of the antenna radiation unit, and the coupling of the metal strips and the main patch optimizes the antenna input impedance matching, so that the compact antenna can also obtain the radiation efficiency and directivity close to that of the full-size patch antenna.

[0020] For the problem that the design frequency band is single and the bandwidth is narrow and cannot cover multiple frequencies, the present application changes the current distribution on the radiation patch by etching a gap, and realizes wideband matching by adjusting the gap size or position without external matching circuit.

[0021] For the problem that the existing high-gain antenna beam is narrow, leading to unstable circular polarization, the present application adopts symmetrical loading metal strips with four-feed feeding mode, and the four feed points are fed with a phase delay of 90° in turn to form stable right-handed circularly polarized radiation, and the phase delay effect of the metal strips helps to widen the 3dB axial ratio beam width. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and / or other aspects of the present application will become more apparent by describing in detail the preferred embodiments thereof with reference to the attached drawings.

[0023] Figure 1 is a structural diagram of the antenna of the present application.

[0024] Figure 2 is a top view of the antenna of the present application.

[0025] Figure 3 is a side view of the antenna of the present application.

[0026] Figure 4 is the S11 curve of the antenna of the present application.

[0027] Figure 5 is the axial ratio bandwidth curve of the antenna of the present application.

[0028] Figure 6 is the influence of the metal strip of the present application on the axial ratio beam width.

[0029] Figure 7 is the axial ratio beam width curve of the antenna of the present application.

[0030] Figure 8 is the gain directivity diagram of the antenna of the present application. DETAILED DESCRIPTION

[0031] The reference signs in the drawings are as follows: 1-metal strip; 2-first radiation patch; 3-second radiation patch; 4-probe; 5-first dielectric plate; 6-second dielectric plate; 7-strip-shaped slot; 8-ring-shaped slot.

[0032] As shown in the drawings, Figures 1-3 The antenna of the application adopts a three-layer dielectric structure, the upper and lower layers are both microstrip substrates, the air layer sandwiched in the middle has a thickness of 9.5 mm, and the total thickness of the air layer and the upper and lower dielectric plates is 17.5 mm. The first radiation patch 2 and the second radiation patch 3 are upper and lower patches respectively, the first dielectric plate 5 has a side length of 75 mm as the first radiation patch 2, and the first radiation patch 2 is engraved with a slot. The thickness of the first dielectric plate 5 and the second dielectric plate 6 is 4 mm, the dielectric constant is 3.5, and the tangent angle loss is 0.0018. The side length of the second dielectric plate 6 is 160 mm, and the length of the metal strip 1 is the same as the side length of the second dielectric plate 6.

[0033] Four strip-shaped slots 7 and four ring-shaped slots 8 are respectively etched on the first radiation patch 2, the strip-shaped slots 7 extend from the center point of the first radiation patch 2 along the radiation direction, and the size is respectively 22.5 mm in length and 1 mm in width. One ring-shaped slot 8 is respectively arranged in the area between the two adjacent strip-shaped slots 7, the ring-shaped slot is composed of two concentric circles, the large circle has a radius of 7 mm, the small circle has a radius of 6 mm, the ring-shaped slot has a width of 1 mm, and the center distance of the ring-shaped slot from the center of the first radiation patch 2 is 18.75 mm, which is one-fourth of the side length of the patch.

[0034] The first radiation patch (2) and the second radiation patch (3) are connected by a plurality of feeding coaxial probes (4) located at the centers of the four ring-shaped slots 8, the probes are cylindrical, the cross-sectional radius of the cylinder is 0.5 mm, the height is 13.5 mm, and the material of the probe (4) is copper

[0035] The feeding system of the antenna is composed of four metal coaxial probes, which are equidistantly distributed in the four quadrants of the upper radiation patch, and are respectively applied with 0°, 90°, 180° and 270° phase shifts through a phase shifter, that is, a sequential rotation feeding method is adopted, the feed points are sequentially rotated by 0°, 90°, 180° and 270° along the center of the array element, and the same amplitude but sequentially delayed 90° excitation signals are respectively injected to realize wideband right-handed circular polarization, and the matching effect is achieved by adjusting the position and distance of the feed points. Each feeding probe is connected with an external feeding line through an SMA female seat to ensure good radio frequency interface matching. The geometric dimensions of the substrate material, the slot and the metal strip and the layer distance are optimized by HFSS simulation, and finally the wide-beam circularly polarized performance with good gain and axial ratio bandwidth in the Beidou B1, B2 and B3 frequency bands is realized.

[0036] As shown in the drawings, Figure 4The antenna optimization simulation results show that the impedance bandwidth of the antenna covers 1.09GHz to 1.64GHz, with a -10dB impedance bandwidth of 40.2%, the wideband performance of the antenna is good, and the curve corresponding to the minimum S11 at 1.43GHz is -36.5dB, indicating that the impedance matching of the antenna is optimal at the frequency. The S11 is less than -15dB in the frequency range of 1.15-1.58GHz, indicating that the antenna can cover multiple navigation frequency bands such as Beidou B1I band (1561.098MHz), B2a band (1176.45MHz), B3 band (1268.52MHz) and the like.

[0037] As shown in Figure 5 , the axial ratio bandwidth of the antenna covers 0.86GHz to 1.97GHz, and the axial ratio is always less than 3dB in the entire GNSS frequency band, with good circular polarization performance and wideband right-handed circular polarization radiation. The circular polarization of the antenna is mainly realized by setting four equal-amplitude excitation points on the patch, sequentially delaying the phase by 0°, 90°, 180° and 270°, and using the superimposed electric field vectors to form a continuous rotation in the main lobe direction, thereby generating high-quality right-handed circularly polarized waves.

[0038] As shown in Figure 6 , the influence of the metal strip on the axial ratio beam width of the antenna is compared. When the working frequency is 1.561GHz and the azimuth is 0, the beam width of the antenna is as shown in Figure 6 . When the metal strip is not added, the 3dB beam width covers -45°-51°, about 96° of circular polarization radiation range, and when the metal strip is symmetrically loaded on both sides of the lower dielectric plate, the 3dB beam width of the antenna covers -61°-79°, about 140° of circular polarization radiation range, and the axial ratio beam width of the antenna is widened by 45% compared with the case without the metal strip. Therefore, it can be known that the metal strip loading realizes wide beam of the antenna.

[0039] As shown in Figure 7 , the axial ratio beam width curves of the antenna at the center frequencies of B1, B2 and B3 frequency bands are shown. As shown in the figure, when the azimuth is 0, the 3dB axial ratio beam width at the center frequency of 1.176GHz is 157°, the 3dB axial ratio beam width at the center frequency of 1.268GHz is 148°, and the 3dB axial ratio beam width at the center frequency of 1.561GHz is 140°. Therefore, the 3dB axial ratio beam width of the antenna in the working frequency band is better than 140°, and has a wide 3dB axial ratio beam width.

[0040] Figure 8 When the azimuth The gain pattern of the antenna at the center frequency of 1.176 GHz when the angle between the two polarization directions is 0 and 90°. As shown in the figure, the peak gain of the main lobe of the antenna is about 9 dB, the half-power beam width is about 80°, and the side lobe is lower than -10 dB. Because the resonant modes introduced by the ring-shaped and strip-shaped slots on the patch are slightly different in the two planes, the gain curves of the two sections are different but similar, indicating that the antenna has good symmetry and consistent directivity in the orthogonal planes.

[0041] The application provides a wide-beam Beidou antenna based on metal strip loading, and there are many methods and approaches for specifically implementing the technical scheme. The above description is only a preferred embodiment of the application, and it should be pointed out that, for ordinary skilled in the art, some improvements and refinements can be made without departing from the principle of the application, and these improvements and refinements should also be regarded as the protection scope of the application. The components not explicitly described in the embodiment can be implemented by using the prior art.

Claims

1. A wide-beam BeiDou antenna based on metal strip loading, characterized in that, It includes a first dielectric plate (5) and a second dielectric plate (6); the upper surface of the first dielectric plate (5) is provided with a first radiating patch (2), the upper surface of the second dielectric plate (6) is provided with a second radiating patch (3), a pair of side surfaces of the second dielectric plate (6) are respectively provided with metal strips (1), there is an air layer between the first dielectric plate (5) and the second dielectric plate (6), the first radiating patch (2) and the second radiating patch (3) are connected by multiple probes (4), and a set of gaps is provided on the first radiating patch (2).

2. The wide-beam BeiDou antenna based on metal strip loading according to claim 1, characterized in that, A set of gaps includes a strip gap group and an annular gap group; the strip gap group includes multiple strip gaps (7) of the same length extending from the center point of the first radiating patch (2) along the radiating direction, and the included angle between adjacent strip gaps (7) is equal; the annular gap group includes the same number of annular gaps (8) of the same size as the strip gaps (7), and an annular gap (8) is provided in the area between two adjacent strip gaps (7), the center of the annular gap (8) is located on the bisector of the included angle between two adjacent strip gaps (7), and the center of the annular gap (8) is equidistant from the center point of the first radiating patch (2).

3. The wide-beam BeiDou antenna based on metal strip loading according to claim 2, characterized in that, The number of probes (4) is the same as the number of annular slits (8). The probes (4) pass through the first dielectric plate (5) and are connected to the first radiation patch (2). The probes (4) are cylinders, and the axis of the cylinder passes through the center of the annular slits (8).

4. The wide-beam BeiDou antenna based on metal strip loading according to claim 3, characterized in that, The number of strip-shaped gaps (7) is four.

5. The wide-beam BeiDou antenna based on metal strip loading according to claim 4, characterized in that, The angle between the extension direction of the strip-shaped slit (7) and the edge of the first radiating patch (2) is 45°.

6. The wide-beam BeiDou antenna based on metal strip loading according to claim 4 or 5, characterized in that, The distance from the center of the annular gap (8) to the center point of the first radiating patch (2) is one-quarter of the side length of the first radiating patch (2).

7. The wide-beam BeiDou antenna based on metal strip loading according to claim 6, characterized in that, The strip-shaped slit (7) and the annular slit (8) have the same slit width.

8. The wide-beam BeiDou antenna based on metal strip loading according to claim 7, characterized in that, The antenna's feeding system is composed of four probes (4). The sequential rotation feeding method applies phase shifts of 0°, 90°, 180°, and 270° respectively through a phase shifter. The feed point rotates 0°, 90°, 180°, and 270° sequentially along the center of the array element. Excitation signals of the same amplitude but delayed by 90° are injected to achieve broadband right-hand circular polarization. The matching effect is achieved by adjusting the position and distance of the feed point.

9. The wide-beam BeiDou antenna based on metal strip loading according to claim 1, characterized in that, The length of the metal strip (1) is the same as the side length of the second dielectric plate (6), and the height of the metal strip (1) is the sum of the thickness of the first dielectric plate (5), the second dielectric plate (6) and the air layer.

10. The wide-beam BeiDou antenna based on metal strip loading according to claim 1, characterized in that, The probe (4) is made of copper.

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