Antenna assembly

Abstract

The present invention relates to an antenna assembly, comprising a dielectric slab and a band control unit. The band control unit comprises: a radiation loop disposed above the dielectric slab and substantially parallel to the dielectric slab; and a first feed structure and a second feed structure connected to the radiation loop at a first feed-in point and a second feed-in point, respectively, the first feed structure and the second feed structure being electrically connected to a first feeder line and a second feeder line, respectively. A connecting line between the first feed-in point and the center of the radiation loop is perpendicular to a connecting line between the second feed-in point and the center of the radiation loop, a plurality of bends arched from a body of the radiation loop toward the dielectric slab are formed at predetermined positions along the circumference of the radiation loop, the body of the radiation loop extends along a hypothetical planar base ring, the bends form a part of the layout, bottoms of the bends extend in a plane at a predetermined distance from and substantially parallel to the dielectric slab, the sizes and positions of the bends are designed such that the parallel capacitive loading introduced between the bottoms of the bends and the dielectric slab enables the resonance of a main mode of the radiation loop in a designed band.

Description

[0001] Description

[0002] Title of the Invention

[0003] Antenna assembly

[0004] Technical Field

[0005] The present invention relates to the field of satellite communication equipment, and in particular to an antenna assembly for satellite positioning.

[0006] Background Art

[0007] Current vehicle-mounted circularly polarized antennas involving high-precision Global Navigation Satellite System (GNSS) satellite positioning are mostly ceramic-substrate patch antennas. Although these ceramic antennas are compact in size, the manufacturing cost of the ceramic substrate is relatively high, and the design cost for expansion from single band to dual bands is even greater. Although other antenna forms such as a dipole, a monopole and a loop antenna can also enable the implementation of the GNSS design, the half-wavelength resonance length requirement has to be met, resulting in physically large sizes that cannot be easily integrated into vehicle designs.

[0008] In satellite positioning antenna systems and other high-precision positioning applications, dual-band antennas are often used for receiving and processing signals at different frequencies to achieve higher positioning accuracy. As signals of different bands experience different phase delays during propagation, it is necessary to ensure that an antenna has the same phase center in two bands to enable the signals of the two bands to be correctly combined and processed, thereby improving the positioning accuracy. As for a high-precision dual-band ceramic patch antenna combined by two thick ceramic blocks stacked one above another, the equivalent phase centers of two frequency points have a height difference in a vertical direction, which is not conducive to meeting the demand for consistency of dual-band phase centers in high-precision positioning.

[0009] Therefore, during the design process of the existing vehicle-mounted antennas (e.g., dual-band dual-feed circularly polarized satellite antennas), there are some challenging design issues, including: large antenna size, insufficient multi-antenna integration density, high antenna profile that is unfavorable for assembly, inconsistent dual-band phase center in the height direction of the high-precision satellite positioning system, high costs for antenna research, development and manufacturing, and the like.

[0010] Summary of the Invention

[0011] The present invention is intended to overcome one or more problems in existing antennas and provides a high-precision GNSS satellite positioning vehiclemounted circularly polarized antenna that is optimized in terms of performance and structure, and has the advantages such as low profilability, high compactness, small size, and low manufacturing cost. The antenna may be used for implementing single-band GNSS vehicle-mounted satellite positioning, and may also be integrated to implement dual-band (e.g., GNSS L1 (1.559-1.606 GHz), GNSS L5 (1 .166-1 .186 GHz) dual-band) or more-band GNSS vehicle-mounted satellite positioning, which has a wide range of application scenarios.

[0012] In view of this, according to an aspect of the present invention, provided is an antenna assembly. The antenna assembly is characterized by comprising a dielectric slab and a band control unit, the band control unit comprising: a radiation loop disposed above the dielectric slab and substantially parallel to the dielectric slab and having a geometrical shape in rotational symmetry; and a first feed structure and a second feed structure, the first feed structure and the second feed structure being electrically connected to the radiation loop at a first feed-in point and the second feed-in point of the radiation loop, respectively, to realize the feeding of the radiation loop, and the first feed structure and the second feed structure being respectively electrically connected to a first feeder line and a second feeder line that are disposed on the dielectric slab, wherein a connecting line between the first feed-in point and a rotational symmetry center of the radiation loop is perpendicular to a connecting line between the second feed-in point and the rotational symmetry center of the radiation loop, a plurality of bends arched from a body of the radiation loop toward the dielectric slab are formed at predetermined positions along the circumference of the radiation loop, the body of the radiation loop extends along a hypothetical planar base ring, the plurality of bends form a part of the layout of the radiation loop, bottoms of the plurality of bends extend in a plane at a predetermined distance from and substantially parallel to the dielectric slab, and the sizes and positions of the plurality of bends are designed such that the parallel capacitive loading is introduced between the bottoms of the bends and the dielectric slab and the parallel capacitive loading introduced enables the resonance of a main mode of the radiation loop within a designed band of the band control unit.

[0013] The antenna assembly according to the present invention has a planar-loop antenna structure and adopts a GNSS single-band double-feed circularly polarized antenna architecture. The radiation loop adopts a square-notch zigzag layout design (hereinafter referred to as the "notched radiation loop"), which effectively introduces a ground-parallel capacitance effect, significantly reduces the antenna size, and occupies a small space of the vehicle. In addition, the antenna assembly according to the present invention may be constructed to have a small side height (e.g., 0.05 Ao), and may be flexibly integrated into the car body plane design to constitute a vehicle-mounted hidden high-precision satellite positioning antenna system. In addition, the antenna assembly according to the present invention may be implemented in the form of an antenna iron member, which is low in manufacturing cost and easy to process and implement.

[0014] Preferably, the plurality of bends each have two opposite vertical walls and a horizontal bottom.

[0015] Preferably, the body of the radiation loop extends along a square hypothetical planar base ring, and the first feed-in point and the second feed-in point of the radiation loop are provided on the body of the radiation loop and at center points of two adjacent sides of the base ring, respectively.

[0016] Preferably, the number of the bends having projections on a side of the base ring where the first feed-in point or the second feed-in point is located is an even number, and the bends are arranged to be symmetrical about a vertical symmetrical plane passing through the center point of the corresponding side.

[0017] Preferably, the antenna assembly comprises two band control units adaptable to different bands, wherein a radiation loop of a first band control unit and a radiation loop of a second band control unit are concentrically disposed above the dielectric slab.

[0018] Preferably, the radiation loop of the first band control unit and the radiation loop of the second band control unit are similar in shape and coincide in plane of symmetry, and the radiation loop of the first band control unit is disposed at a predetermined distance to the inner side of the radiation loop of the second band control unit. Preferably, a plane where a body of the radiation loop of the first band control unit is located coincides with a plane where a body of the radiation loop of the second band control unit is located, and a plane where the bottoms of the bends of the radiation loop of the first band control unit are located coincides with a plane where the bottoms of the bends of the radiation loop of the second band control unit are located.

[0019] Preferably, a hypothetical planar base ring of the radiation loop of the first band control unit and a hypothetical planar base ring of the radiation loop of the second band control unit are square, a first feed-in point and a second feed-in point of the radiation loop of the first band control unit are respectively provided on the body of the radiation loop of the first band control unit, a first feed-in point and a second feed-in point of the radiation loop of the second band control unit are respectively provided on the body of the radiation loop of the second band control unit, the hypothetical planar base rings of the two radiation loops have two common diagonals, the first feed-in point and the second feed-in point of the radiation loop of the first band control unit are symmetrically provided, about the first diagonal of the two common diagonals, at center points of two adjacent sides of the hypothetical planar base ring of the radiation loop of the first band control unit respectively, the first feed-in point and the second feed-in point of the radiation loop of the second band control unit are symmetrically provided, about the first diagonal, at center points of two adjacent sides of the hypothetical planar base ring of the radiation loop of the second band control unit respectively, the first feedin point and the second feed-in point of the radiation loop of the first band control unit and the first feed-in point and the second feed-in point of the radiation loop of the second band control unit are provided at different sides of the second diagonal of the two common diagonals. According to the design structure of the dual-band antenna assembly of the present invention, in addition to the advantages of a single-band antenna assembly (e.g., realizing the resonance of the main mode in the desired band while reducing the size), it is also possible to adjust the relative positions of the two nested notched radiation loops to make the centers of the two radiation loops corresponding to two different GNSS operating frequencies coincide, thus achieving more desirable dual-band equivalent phase center consistency, and improving the performance of the high-precision satellite positioning system. In addition, the dual-band antenna assembly according to the present invention has a low-profile structural characteristic (e.g., an overall side height of O.O5Ao) compared with the existing dual-band antenna assembly, and may be flexibly integrated into the car body plane design to constitute the vehicle-mounted hidden satellite positioning antenna system.

[0020] Preferably, the antenna assembly comprises three or more band control units, the radiation loops of the respective band control units are concentrically disposed above the dielectric slab, two adjacent radiation loops are spaced apart by a predetermined distance, the radiation loops of all of the band control units have a similar shape and coincide in the plane of symmetry, planes where the radiation loops of all of the band control units are located coincide, and planes where the bottoms of the bends of the radiation loops of all of the band control units are located coincide.

[0021] Preferably, the first feed structure and the second feed structure implement the feeding of the radiation loop in a coupled feed manner.

[0022] Preferably, the first feed structure and / or the second feed structure have vertical posts and transverse coupling portions, which are substantially formed in a T or L shape.

[0023] Preferably, the transverse coupling portions have coupled feed surfaces facing the lower side of the body of the radiation loop.

[0024] Preferably, the radiation loop is an integrally molded metal ring. Therefore, the respective radiation loops of the antenna assembly according to the present invention may be concretely implemented as loop iron members and accordingly have the advantage of low manufacturing cost.

[0025] Preferably, the dielectric slab is a printed circuit board (PCB).

[0026] The antenna assembly according to the present invention provides an optimized solution for the miniaturization design of a vehicle-mounted satellite positioning antenna, making it possible to achieve the single-band / dual-band high-precision satellite positioning performance in a smaller size. The antenna assembly according to the present invention may be preferably used as a hidden vehiclemounted circularly polarized antenna for high-precision GNSS satellite positioning. The circularly polarized antenna may be used for receiving and transmitting various types of circularly polarized signals, such as GPS signals, mobile communication signals, satellite TV signals, and broadcasting station signals. As compared with linearly polarized signals, such circularly polarized signals have better transmission performance, with signal attenuation and multipath interference effectively reduced. In addition, the circularly polarized antenna assembly according to the present invention can not only realize single-band signal transmission, but also be integrated for dual-band or more-band signal transmission for GNSS vehicle-mounted satellite positioning, has significantly reduced size and low-profile structural characteristic, and accordingly may be flexibly integrated into the car body plane design. The present invention is ready to provide a dual-band or multi-band antenna assembly with desirable equivalent phase center consistency. Moreover, these antenna assemblies have a simple manufacturing process and low manufacturing cost and are easy to mass produce.

[0027] Brief Description of the Drawings

[0028] Through the accompanying drawings herein and the specific embodiments subsequently used in conjunction with the accompanying drawings to show some of the principles of the present invention, other features and advantages of the methods of the present invention will become clear or will be more specifically illustrated.

[0029] FIG. 1 shows a perspective diagram of an antenna assembly according to a first embodiment of the present invention;

[0030] FIG. 2 shows a side view of the antenna assembly according to the first embodiment of the present invention;

[0031] FIG. 3 shows S-parameter curves of the antenna assembly according to the first embodiment of the present invention in response to different depths of bends;

[0032] FIG. 4 shows a first example of a feed structure in the antenna assembly according to the first embodiment of the present invention;

[0033] FIG. 5 shows an S-parameter curve of the antenna assembly shown in FIG. 4;

[0034] FIG. 6 shows a second example of the feed structure in the antenna assembly according to the first embodiment of the present invention;

[0035] FIG. 7 shows an S-parameter curve of the antenna assembly shown in FIG. 6;

[0036] FIG. 8 shows a third example of the feed structure in the antenna assembly according to the first embodiment of the present invention;

[0037] FIG. 9 shows an S-parameter curve of the antenna assembly shown in FIG. 8;

[0038] FIG. 10 shows a perspective diagram of an antenna assembly according to a second embodiment of the present invention; and

[0039] FIG. 11 shows an S-parameter curve of the antenna assembly shown in FIG. 10.

[0040] Detailed Description of the Invention

[0041] An antenna assembly according to the present invention will be described below with reference to the accompanying drawings and by way of embodiments. Many details are given in the following description so that those skilled in the art can understand the invention more comprehensively. However, it will be obvious to those skilled in the art that the invention can be realized without some of these details. On the contrary, one may consider using any combination of the following characteristics and elements to implement the invention, regardless of whether they relate to different embodiments. Therefore, the following various aspects, characteristics, embodiments and advantages are only used to describe the invention, and should not be regarded as elements or definitions of the claims.

[0042] First embodiment of the antenna assembly according to the present invention

[0043] FIGS. 1 and 2 show an antenna assembly T according to a first embodiment of the present invention. The illustrated antenna assembly T has a single-band loop antenna structure. The antenna assembly T comprises a dielectric slab 12 and a band control unit 10' configured to control the performance of the antenna assembly in a particular band. The dielectric slab 12 may be implemented as a PCB. Referring to FIG. 1 , the dielectric slab is placed substantially horizontally. The entire bottom surface of the dielectric slab is covered with a metal layer, such as a copper layer. A first feeder line 10T and a second feeder line 102' are etched on an upper surface of the dielectric slab.

[0044] The band control unit 10' includes a radiation loop 100' and a first feed structure 100T and a second feed structure 1002'. The radiation loop 100' is constructed, for example, in the form of an integrally molded metal ring. The radiation loop is disposed above the dielectric slab 12 and substantially parallel to the dielectric slab, and has a geometrical shape in rotational symmetry. The radiation loop 100' may be positioned relative to the dielectric slab by a support structure (not shown). The first feed structure 100T and the second feed structure 1002' are respectively electrically connected, on the one hand, to the first feeder line 10T and the second feeder line 102' that are disposed on the dielectric slab 12, and on the other hand are connected to the radiation loop 100' at the first feed-in point F1 and the second feed-in point F2 of the radiation loop respectively, thereby realizing the feeding of the radiation loop.

[0045] A connecting line between the first feed-in point F1 and a rotational symmetry center O of the radiation loop 100' is perpendicular to a connecting line between the second feed-in point F2 and a rotational symmetry center O of the radiation loop 100', such that one of the feed-in points will feed a signal at a zero position of an electric field excited by the other feed-in point on the radiation loop. In the embodiment shown in FIG. 1 , the radiation loop adopts coupled feed. A metal layer (e.g., copper) covering the bottom surface of the dielectric slab is used as a ground plane, i.e., as the ground for the first feeder line 101' and the second feeder line 102' and for the radiation loop 100'. Although the ground plane is shown to be located at the bottom of the dielectric slab, it can be understood that the ground plane may also be provided as other layers of the dielectric slab. For example, the ground plane may be disposed on the upper layer of the dielectric slab, and accordingly, the first feeder line 101' and the second feeder line 102' may be disposed on the bottom layer of the dielectric slab.

[0046] In the antenna assembly T according to the present invention, a plurality of bends 100w’ arched from a body of the radiation loop toward the dielectric slab are formed at predetermined positions along the circumference of the radiation loop 100'. Bottoms of the plurality of bends 100w' extend in a plane P1 at a predetermined distance from the dielectric slab 12 and substantially parallel to the dielectric slab. The body 100b' of the radiation loop 100' extends along a hypothetical planar base ring BC. The hypothetical planar base ring is a closed ring obtained by projecting the entire radiation loop 100' on a plane P2 where the body of the radiation loop is located. The plurality of bends 100w' of the radiation loop form a part of the layout of the radiation loop. The part of the layout is essential for the closure of the hypothetical planar base ring.

[0047] That is, the entire radiation loop may be viewed as a closed loop layout, which is formed of a body layout part corresponding to the body of the radiation loop and bend layout parts corresponding to the bends in an end-to-end connected manner. The body layout part is spaced apart along the circumference of the hypothetical planar base ring. The bend layout parts are below a plane where the body of the radiation loop is located, and their projections on the plane where the body of the radiation loop is located fall exactly in gaps among the body layout parts, thereby forming the closed hypothetical planar base ring. With the arrangement of the bends, the closed loop layout corresponding to the entire radiation loop is a three- dimensional zigzag layout. The entire radiation loop may be referred to as a notched radiation loop.

[0048] In the antenna assembly T according to the present invention, the sizes and positions (including the shape, size, configuration, distribution, and positioning) of the plurality of bends 100w' are designed such that the parallel capacitive loading is introduced between the bottoms of the bends and the dielectric slab and the parallel capacitive loading introduced enables the resonance of a main mode of the radiation loop within a designed band of the band control unit 10'.

[0049] In the specific embodiment shown in FIG. 1 , the bends 100w' are each designed in the form of a basic notch, i.e., having two opposing vertical walls 100wT and a horizontal bottom 100w2'. The hypothetical planar base ring corresponding to the body of the radiation loop is shown as square. The first feed-in point F1 and the second feed-in point F2 of the radiation loop 100' are provided on the body 100b' of the radiation loop and at center points of two adjacent sides of the square hypothetical planar base ring BC, respectively.

[0050] With cooperation between the first feeder line 10T and the first feed structure 100T, the radiation loop forms an electric field distribution pattern in which the electric field is strongest at two sides and weakest at the center. Moreover, in this electric field operating pattern, the weakest point of the electric field strength is just at a feeding position of the second feeder line 102' and the second feed structure 1002', while the second feed structure performs coupled feed to the radiation loop, thereby forming a high isolation of double feed ports. With this dual-feed structure, two orthogonal components of linearly polarized radiation may be excited in a far- field space, and then circularly polarized radiation may be formed in conjunction with feed phase shifting. Although the first feed-in point F1 and the second feed-in point F2 shown in FIG. 1 are located at the center points of adjacent sides of the square hypothetical planar base ring of the radiation loop, respectively, it can be understood that the first feed-in point F1 and the second feed-in point F2 may also be out of the center positions of adjacent sides of the square hypothetical planar base ring BC of the radiation loop, provided that the connecting line between the first feed-in point F1 and the rotational symmetry center 0 of the radiation loop 100' is perpendicular to the connecting line between the second feed-in point F2 and the rotational symmetry center 0 of the radiation loop 100'.

[0051] In the embodiment illustrated in FIG. 1 , each side of the radiation loop is provided with bends. The number of bends 100w' on each side of the radiation loop is 2. Two bends on the same side of the radiation loop are symmetrical about a vertical plane of symmetry of the radiation loop that passes through the center point of the corresponding side of the hypothetical planar base ring. The shapes and positions of the bends 100w' on each side of the radiation loop are designed such that the entire radiation loop remains rotationally symmetric, i.e., after the entire radiation loop is rotated horizontally by a specific angle about a vertical axis passing through the rotational symmetry center thereof, it coincides with the original radiation loop. The property of rotational symmetry ensures that the first feed-in point F1 and the second feed-in point F2 in a direction orthogonal to it at 90° produce equal-amplitude orthogonal linearly polarized components, thus facilitating the formation of a circularly polarized radiation beam in space.

[0052] In the embodiment of the antenna assembly according to the present invention shown in FIG. 1 , each side of the notched radiation loop is provided with two bends. In the case of a side kk, for example, the two bends provided thereon are symmetrical about a vertical symmetry plane M (which is perpendicular to the paper surface of FIG. 2) where the first feed structure F1 is located. It is assumed that the length of the outer side of the planar base ring BC is Lo. The length of the vertical wall 100wT of each bend 100w' (i.e., the depth of the bend) is gap_z. A vertical spacing between the plane P2 where the body of the radiation loop is located and the dielectric slab 12 is Ho. A spacing between the horizontal bottom 100w2' of the bend and the dielectric slab 12 is g=Ho-gap_z. The width of the horizontal bottom of the bend 100w' in a layout direction of the radiation loop 100' is L. In a direction perpendicular to the layout, the horizontal bottom of the bend has a bandwidth of W. Capacitive loading C=f(g, L, W) is introduced between the bottom of the bend and the dielectric slab 12. This equation represents the loading capacitance as a function of g, L and W.

[0053] The bends formed on each side of the radiation loop are coupled to the dielectric slab at the bottom, thereby creating a distributed parallel capacitive loading effect. With the arrangement of the bends, it is possible to extend the path length of a current loop while keeping the length Lo of the outer side of the hypothetical planar base ring BC of the radiation loop unchanged. That is, for a specific path length of the current loop, the side length of the hypothetical planar base ring of the radiation loop may be designed smaller, which means that the overall size in a horizontal direction of the radiation loop is reduced.

[0054] Moreover, under the same limitation requirements for the size in the horizontal direction, the longer the path through which the current flows, the lower the resonance point of the notched radiation loop. In the embodiment shown in FIG. 2, for each additional bend, the length of the path through which the current flows is increased by 2gap_z. In other words, the addition of the bend 100w' enables the introduction of a dense local layout below the plane where the body of the radiation loop is located, so that a close coupling effect between the bends and the dielectric slab can be introduced skilfully, the electrical size can be extended while the profile height of the antenna assembly can be reduced.

[0055] In the antenna assembly according to the present invention, the strength of the close coupling between the bends and the dielectric slab as well as the resulting parallel capacitive loading effect is adjusted selectively. Taking the equivalent capacitive loading of capacitors C1 and C2 shown in FIG. 2 as an example, based on the electrical principle, the capacitors C1 and C2 are equivalent distributed capacitors distributed in a close coupling space between the bottoms of the bends and the dielectric slab. In the electrical position, the parallel capacitor introduced in the bend layout part is loaded at an effective node of the current loop combination structure. The capacitance of the capacitor C1 and the capacitor C2 is related to the degree of coupling generated between the bottoms of the bends and the dielectric slab 12. In other words, the smaller distance g between the bottoms of the bends and the dielectric slab leads to the stronger degree of coupling and the higher capacitance value, and conversely, the greater distance g between the bottoms of the bend and the dielectric slab leads to the weaker degree of coupling and the smaller capacitance value. The smaller the distance g is, the stronger the degree of coupling is, the larger the capacitance value is, the closer it converges to the short-circuit point on the left side of the Smith Chart, and the closer the parallel capacitor converges to the short-circuit state. The greater the distance g is, the weaker the degree of coupling is, the smaller the capacitance value is, the weaker the effect of reducing the size played by the parallel capacitors is, and the effect of the loading is not obvious. Therefore, in the antenna assembly T of the present invention, the parallel capacitive loading introduced is selectively controlled in an appropriate range by the specific design of the sizes and positions of the bends 100w', so that the capacitance value is moderate, the parallel capacitance increases the amount of the phase change of the resonant structure, the main mode (i.e. , the fundamental mode) realizes the resonance at lower frequency point, the physical length required is shorter, and the resonance point can be effectively shifted to a lower frequency. For example, as shown in FIG. 3, with the overall profile size of the antenna assembly unchanged, when the profile height of the current loop zigzag layout is lowered vertically, the resonance point changes from 1.3 GHz to 1.15 GHz as the depth gap_z of the bends changes from 6.5 mm to 8.0 mm, resulting in a significant shift in the frequency point.

[0056] Although the antenna assembly of the present invention is illustrated above using the example of the radiation loop in which the hypothetical planar base ring is square, it can be understood that the radiation loop may be implemented to have other rotationally symmetrical shapes. The bends of the radiation loop may also be designed as notches of other configurations, such as a tear-drop shape or a triangle shape in the side view, for example. In the radiation loop in which the hypothetical planar base ring is square, the number of bends provided on each side may also be an even number different from 2.

[0057] Embodiments of coupled feed structure

[0058] In the first embodiment of the antenna assembly of the present invention, the first and second feeder lines perform coupled feed to the radiation loop through the first feed structure and the second feed structure, respectively. The coupled feed may achieve an equivalent distributed series capacitance effect. First example of the coupled feed structure

[0059] As shown in FIG. 4, the first feed structure 1001' and the second feed structure 1002' are shown as including, respectively, metal connecting posts 1001 '-1a, 1002'-1a extending between the radiation loop 100' and the dielectric slab 12 and patches 1001 '-2a, 1002'-2a disposed on the metal connecting posts, passing through upper ends of circular holes etched in the radiation loop and spaced from the radiation loop in a vertical direction. The patches 1001'-2a, 1002'-2a are preferably circular. Projection positions of the patches of the first feed structure 100T and the second feed structure 1002' on the radiation loop are the first feed-in point F1 and the second feed-in point F2 of the radiation loop. Bottom ends of the metal connecting posts 1001'-1a, 1002'-1a are connected to the feeder lines 10T, 102' etched, for example, on an upper surface of the dielectric slab 12.

[0060] In the embodiment shown in FIG. 4, the first feed-in point F1 and the second feedin point F2 are provided on the body 100b' of the radiation loop 100' and at center points of two adjacent sides of the square hypothetical planar base ring BC, respectively. In this case, the first feed structure and the second feed structure perform coupled feed with a naturally high isolation at the zero pole of the electric field, which further reduces the coupling between double feed ports and facilitates the obtaining of a dual-feed antenna design.

[0061] With the first and second feed structures in the first example form employing the coupled feed structure, electrical parameters of the antenna assembly according to the present invention are shown in FIG. 5. With the square hypothetical planar base ring having dimensions of 48mm X 48mm, the S-parameter resonance point of the antenna assembly according to the present invention may satisfy the operational requirements for the GNSS satellite positioning. Second example of the coupled feed structure

[0062] FIG. 6 shows first and second feed structures as coupled feed structures different from the form shown in FIG. 4. The first feed structure 100T and the second feed structure 1002' are implemented as including vertical metal posts 1001'-1 b, 1002'- 1b extending between the radiation loop and the dielectric slab and transverse coupling portions 1001'-2b, 1002'-2b close to the body of the radiation loop. A bottom end of the vertical metal post 1001'-1b is connected to the feeder lines 10T, 102' etched, for example, on the upper surface of the dielectric slab. The vertical metal posts 1001'-1 b, 1002'-1 b are positioned in the inner space surrounded by the radiation loop. For example, the transverse coupling portions 1001'-2b, 1002'-2b integrally provided on the upper side of the vertical metal posts 1001'-1 b, 1002'-1 b, respectively, extend along the inner side of the body 100b' of the radiation loop. The first and second feed structures shown in FIG. 6 may be substantially formed in a T-shape. The transverse coupling portions have coupled feed surfaces 100T-CF, 1OO2'-CF facing the inner side of the body 100b' of the radiation loop. The distance between the coupled feed surface and the body of the radiation loop and the size of the coupled feed surface may be set according to the coupling strength requirement.

[0063] Although the feed structure shown in FIG. 6 is substantially T-shaped, it can be understood that it may also be constructed in an L-shape or other shapes as long as it meets the coupled feed strength requirements for the radiation loop.

[0064] With the first and second feed structures in the second example form employing the coupled feed structure shown in FIG. 6, the antenna assembly T according to the present invention may obtain electrical parameters as illustrated in FIG. 7.

[0065] Third example of the coupled feed structure FIG. 8 shows the first and second feed structures as coupled feed structures similar to the coupled feed structures shown in FIG. 6, which include vertical metal posts 1001 '-1c, 1002'-1c extending between the radiation loop 100' and the dielectric slab 12 and transverse coupling portions 1001 '-2c, 1002'-2c close to the body of the radiation loop. Bottom ends of the vertical metal posts 1001 '-1c, 1002'- 1c are connected to the feeder lines 101', 102' etched, for example, on the upper surface of the dielectric slab. The vertical metal posts 1001'-1c, 1002'-1c are positioned on the lower side of the body 100b' of the radiation loop 100'. For example, the transverse coupling portions 1001'-2c, 1002'-2c integrally provided on the upper side of the vertical metal posts extend along the lower side of the body 100b' of the radiation loop. The first and second feed structures shown in FIG. 8 may be substantially formed in a T-shape. The transverse coupling portions 1001'-2c, 1002'-2c have coupled feed surfaces 100T-CF, 1OO2'-CF facing the lower side of the body 100b' of the radiation loop. The distance between the coupled feed surface and the body of the radiation loop and the size of the coupled feed surface may be set according to the coupling strength requirement.

[0066] Although the coupled feed structure shown in FIG. 7 is substantially T-shaped, it can be understood that it may also be constructed as an L-shape or other shapes as long as it can satisfy the coupled feed strength requirements for the radiation loop.

[0067] With this coupled feed structure, the coupled feed of the radiation loop is configured to be extremely hidden, and will not occupy the installation space of other surrounding parts. In addition, the antenna assembly using this coupled feed structure, according to the present invention, may obtain excellent electrical parameters, as shown in FIG. 9. Although only three different forms of the coupled feed structure are exemplified, it can be understood that the coupled feed structure suitable for the antenna assembly of the present invention is not limited to the above three forms.

[0068] Although in the embodiment shown in FIGS. 1 , 4, 6 and 8, the radiation loop 100' is coupled-fed at the first feed-in point F1 and the second feed-in point F2, the coupled feed structure has the more beneficial effect of optimizing impedance matching and increasing the isolation between ports. However, it can be understood that in the antenna assembly according to the present invention, it is also possible to perform direct feed to the radiation loop, for example by electrically connecting the upper ends of the coupling metal posts to the radiation loop by welding. Herein, "feed-in point" refers to a region where the feeding occurs, such as a projection region of each patch in the vertical direction in FIG. 4 or a projection region of a coupling surface in a coupling direction in FIGS. 6 and 8.

[0069] Whether a direct feed structure or a coupled feed structure is used, the antenna assembly according to the present invention that employs the zigzag layout design may obtain both the beneficial effects of introducing coupling with the dielectric slab and the lengthening of the current path in the vertical direction. The coupling with the dielectric slab is formed by zigzagging the bends in the notched radiation loop to a reduced height, and the coupling creates a distributed parallel capacitive loading effect, which increases the phase variation of the resonant structure, enables the resonance of the main mode at a lower frequency point, and makes the desired physical length shorter. In addition, the zigzag layout prolongs a path in the vertical direction, further increasing the physical length of the current loop. With the combination of these two effects, the notched radiation loop may effectively shift a GNSS operating resonance point towards a lower frequency. In other words, the zigzag layout of the notched radiation loop makes it easy to achieve the resonance operating frequency point of the GNSS antenna under the same dimension limitation.

[0070] The antenna assembly according to the present invention has substantially a planar-loop antenna structure, which is implemented on the basis of a metal ring (e.g., an annular iron member). The compact notched radiation loop design has the advantages of reducing the size, reducing the profile height (overall side height) and achieving a high antenna integration, and may be flexibly integrated into the car body plane design to constitute a vehicle-mounted hidden satellite positioning antenna system. Moreover, the symmetry of the overall structure guarantees two orthogonally polarized components of equal amplitude, which facilitates the generation of the circularly polarized satellite positioning beam. The antenna architecture is also easy to extend to give a dual-band dual-feed antenna structure in which dual radiation loops are in the same plane and centers of the two loops are consistent, thus ensuring the phase center consistency required for high-precision satellite positioning. In addition, the entire radiation loop may be implemented by the processing technology such as integrated molding of iron members, which is simple and low in cost.

[0071] Second embodiment of the antenna assembly according to the present invention Based on the above-described first embodiment having a single-band loop antenna architecture, the second embodiment having a dual-band design may be further extended.

[0072] Referring to FIG. 10, an antenna assembly 1" according to the second embodiment of the present invention comprises two band control units. A first band control unit 10"-1 and a second band control unit 10"-2 have the same configuration as the band control unit in the first embodiment of the present invention.

[0073] That is, the first band control unit 10"-1 has a radiation loop 100"-1 , and a first feed structure 1001"-1 and a second feed structure 1002"-1 for performing coupled feed of the corresponding radiation loop 100"-1. The first feed structure 1001"-1 of the first band control unit 10"-1 performs coupled feed to the radiation loop at a first feed-in point F1 -1 and is connected, at its bottom end, to a first feeder line 101"-1 provided on the dielectric slab 12. The second feed structure 1002"-1 of the first band control unit 10"-1 performs coupled feed to the radiation loop 100"-1 at the second feed-in point F2-1 , and is connected, at its end, to a second feeder line 102"-1 provided on the dielectric slab 12.

[0074] The second band control unit 10"-2 has a radiation loop 100"-2, and a first feed structure 1001 "-2 and a second feed structure 1002"-2 for performing coupled feed of the corresponding radiation loop 100"-2. The first feed structure 1001 "-2 of the second band control unit 10"-2 performs coupled feed to the radiation loop at a first feed-in point F1 -2 and is connected, at its bottom end, to a first feeder line 101 "-2 provided on the dielectric slab 12. The second feed structure 1002"-2 of the second band control unit 10"-2 performs coupled feed to the radiation loop 100"-2 at the second feed-in point F2-2, and is connected, at its bottom end, to a second feeder line 102"-2 provided on the dielectric slab 12.

[0075] The radiation loop 100"-1 of the first band control unit 10"-1 and the radiation loop 100"-2 of the second band control unit 10"-2 are concentrically disposed above the dielectric slab 12. Herein, "concentric" means that center axes of rotation of the two radiation loops substantially coincide, and centers of rotational symmetry of the two radiation loops substantially coincide. In the embodiment shown in FIG. 10, the radiation loop 100"-1 of the first band control unit 10"-1 and the radiation loop 100"-2 of the second band control unit 10"-2 are similar in shape and coincide in the plane of symmetry. The radiation loop 100"-1 of the first band control unit 10"-1 is disposed on the inner side of the radiation loop 100"-2 of the second band control unit 10"-2, and the two are spaced by a predetermined distance.

[0076] In the embodiment of the dual-band loop antenna shown in FIG. 10, the first band control unit 10"-1 of the radiation loop 100"-1 located on the inner side is a high- band control unit. The second band control unit 10"-2 of the radiation loop 100"-2 located at the periphery is a low band control unit. That is, the applicable frequency of the first band control unit is higher than that of the second band control unit.

[0077] In the favorable embodiment shown, a plane where a body 100"-1 of the radiation loop of the first band control unit is located coincides with a plane where a body 100"-2 of the radiation loop of the second band control unit is located, and a plane where the bottoms of the bends 100w"-1 of the radiation loop 100"-1 of the first band control unit are located coincides with a plane where the bottoms of the bends 100w"-2 of the radiation loop 100"-2 of the second band control unit are located. Thus, it is ensured that the two radiation loops are substantially in the same plane.

[0078] In the embodiment shown in FIG. 10, a hypothetical planar base ring BC-1 of the radiation loop 100"-1 of the first band control unit and a hypothetical planar base ring BC-2 of the radiation loop 100"-2 of the second band control unit are square. A first feed-in point F1-1 and a second feed-in point F2-1 of the radiation loop 100"-1 of the first band control unit 10"-1 are provided respectively on the body 100b"-1 of the radiation loop 100"-1 of the first band control unit 10"-1 . A first feed point F1-2 and a second feed point F2-2 of the radiation loop 100"-2 of the second band control unit 10"-2 are provided respectively on the body 100b"-2 of the radiation loop 100"-2 of the second band control unit 10"-2.

[0079] The hypothetical planar base ring BC-1 , BC-2 of the two radiation loops have two common diagonals k1 , k2. The first feed-in point F1-1 and the second feed-in point F2-1 of the radiation loop 100"-1 of the first band control unit 10"-1 are symmetrically provided, about the first diagonal k1 of the two common diagonals, respectively, at the center points of two adjacent sides of the hypothetical planar base ring BC-1 of the radiation loop of the first band control unit. The first feed-in point F1-2 and the second feed-in point F2-2 of the radiation loop 100"-2 of the second band control unit 10"-2 are symmetrically provided, about the first diagonal k1 , respectively, at the center points of two adjacent sides of the hypothetical planar base ring BC-2 of the radiation loop 100"-2 of the second band control unit 10"-2. The first feed-in point F1-1 and the second feed-in point F2-1 of the radiation loop 100"-1 of the first band control unit 10"-1 , and the first feed-in point F1-2 and the second feed-in point F2-2 of the radiation loop 100"-2 of the second band control unit 10" -2 are provided at different sides of the second diagonal k2 of the two common diagonals.

[0080] That is, without affecting the design of the notched radiation loop of the high-band control unit, the addition of the low-band control unit above the same dielectric slab 12 is facilitated by providing the notched radiation loop having a large size and a corresponding matching feed structure at the periphery of the radiation loop above the dielectric slab 12. In other words, a notched radiation loop of a different GNSS operating band may be easily added to form a notched dual-loop antenna without affecting the operation of the single loop. The notched dual-loop antenna is integrated with two operating bands (e.g. satellite positioning bands GNSS L1 (1.559-1.606 GHz) and GNSS L5 (1.166-1.186 GHz)) for GNSS vehicle-mounted satellite positioning.

[0081] In the antenna assembly according to the second embodiment of the present invention, the loop planar antenna architecture is conducive to independently developing a dual-band, dual-feed circularly polarized GNSS satellite positioning antenna. In the integrated dual-band planar design, the centers of the two radiation loops are consistent and there is no distance difference in the height direction which is conducive to meeting the requirement of high-precision satellite positioning with consistent phase center. The ultra-low-profile structure may be flexibly integrated into the car body plane design, which facilitates the development of the vehicle-mounted hidden satellite positioning antenna system.

[0082] The electrical performance of the extended dual-band antenna assembly according to the present invention is shown in FIG. 11 , and the S-parameter resonance point of the antenna assembly may satisfy the operating requirements of GNSS positioning in response to the overall dimensions of 48mmx48mm.

[0083] Overall, the design of the antenna assembly with the notched radiation loop according to the present invention is conducive to reducing the antenna size; the ultra-low profile structure may be flexibly integrated into the car body plane design, which facilitates the development of the vehicle-mounted hidden satellite positioning antenna system. In addition, the extended dual-band antenna assembly adopts an integrated design, which is conducive to achieving the consistency of phase centers and meeting the requirements of the high-precision satellite positioning system. In addition, the notched loop and its corresponding coupled feed structure may use the integrated molding process for iron members, which has low manufacturing cost and is easy to be processed and assembled.

[0084] Multi-band antenna assembly according to the present invention

[0085] Based on the single-band antenna assembly according to the first embodiment of the present invention and / or the dual-band antenna assembly according to the second embodiment of the present invention, a multi-band antenna assembly (not shown) having more (i.e. , three or more) band control units may be extended. In the multi-band antenna assembly, the radiation loops of the respective band control units are concentrically disposed above the dielectric slab, two adjacent radiation loops are spaced apart by a predetermined distance, the radiation loops of all of the band control units have a similar shape and coincide in the plane of symmetry, planes where the radiation loops of all of the band control units are located coincide, and planes where the bottoms of the bends of the radiation loops of all of the band control units are located coincide.

[0086] The multi-band antenna assembly according to the present invention also has an ultra-low profile characteristic and small-sized loop planar antenna structure, may be flexibly integrated into the car body plane design, and is adaptable to the vehicle-mounted hidden antenna of the high-precision GNSS satellite positioning system. In addition, without affecting the operation of the current radiation loop, it is convenient to add radiation loops for different GNSS bands and matching feed structures so as to obtain a multi-band multi-feed antenna structure, thereby expanding the applicable range of bands of the antenna assembly, making it possible to integrate the control portions of multiple bands on the top of the same dielectric slab, which further improves the compactness of the antenna assembly as well as its integration. In addition, the radiation loops of all the band control units are substantially in the same plane, centers of the radiation loops are consistent, and there is no distance difference in the height direction, thus ensuring the phase center consistency for high-precision satellite positioning. Moreover, by flexibly adjusting the parameters of the bends, the radiation loops may be designed to have suitable physical dimensions, making it easy to simultaneously realize the integration of the radiation loops for different bands while ensuring the phase center consistency.

[0087] Although the radiation loops of the single-band antenna assembly, the dual-band antenna assembly, and the multi-band antenna assembly described above are shown as having a square structure, it can be understood that the radiation loops of rotationally symmetrical geometric shapes other than a square may be used for the antenna assembly according to the present invention. The shape includes, for example, a circle, an ellipse, a triangle, a pentagon, and a hexagon. Although the coupled feed structure is illustrated as an example for the single-band antenna assembly, it can be understood that the coupled feed structure may also be used for the dual-band or multi-band antenna assembly. Furthermore, the first feed-in point and the second feed-in point in each band control unit are arranged on the corresponding radiation loop in such a way that a specific zero-pole point electric field distribution pattern is formed. This zero-pole electric field distribution pattern, in combination with the coupled feed, greatly reduces the coupling between the feed ports. The symmetrical characteristic of the overall ring-shaped radiation structure guarantees two orthogonally polarized components of equal amplitude, which facilitates the generation of a circularly polarized beam (e.g. circularly polarized satellite positioning beam).

[0088] In summary, the antenna assembly according to the present invention is capable of achieving at least one of the following advantages: Structural characteristics: It has a planar loop antenna structure. With a compact and size-reduced three-dimensional zigzag layout design, a hidden low-profile antenna architecture as well as a planar integrated single-band / dual-band / multi- band antenna is obtained.

[0089] Electrical characteristics: The high-integration multi-port multi-band expansion is facilitated. In addition, for the dual-band or multi-band antenna architecture, the high phase center consistency ensures meeting of the requirements of high- precision GNSS satellite positioning.

[0090] Engineering characteristics: It is implemented based on a metal ring (e.g. annular iron parts). It has a simple process and low manufacturing cost, is easy to assemble, and it is easy to achieve mass production.

[0091] Herein, the orientation words "upper", "lower", "top" and "bottom" indicate the orientation of the antenna assembly when it is placed in the attitude shown in FIG.

[0092] 1. These orientation words are introduced to facilitate the description of the structure of the antenna assembly and do not constitute any substantial limitation thereof.

[0093] Herein, "high" and "low" in "a high-band control unit" and "a low-band control unit" refer to the comparison of the applicable frequencies to each other. The range in which the specific bands are located corresponds to the sizes of the corresponding radiation loops. Here, it is not intended to limit the applicable frequencies of the high-band control unit and the low-band control unit to a particular range.

[0094] It can be understood by those skilled in the art that the various steps of the method according to the present invention are not limited to being performed in the order enumerated above. In addition, in the present invention, in addition to terms such as “include” and “comprise” meaning the steps that are directly and explicitly expressed in the description and claims, the technical solution of the present application does not exclude the circumstance where there are other steps that are not directly or explicitly expressed.

[0095] Although the present invention has been disclosed as above by way of preferred embodiments, the present invention is not limited thereto. Any change or modification made by those skilled in the art without departing from the spirit and scope of the present invention should be included in the scope of protection thereof. Thus, the scope of protection of the present invention shall be the scope defined by the claims.

Claims

Claims1. An antenna assembly, comprising a dielectric slab (12) and a band control unit (10'), the band control unit comprising: a radiation loop (100') disposed above the dielectric slab and substantially parallel to the dielectric slab and having a geometrical shape in rotational symmetry; and a first feed structure (1001 ') and a second feed structure (1002'), the first feed structure and the second feed structure being electrically connected to the radiation loop at a first feed-in point (F1 ) and the second feed-in point (F2) of the radiation loop, respectively, to realize the feeding of the radiation loop, and the first feed structure and the second feed structure being electrically connected to a first feeder line (101 ') and a second feeder line (102'), respectively, that are disposed on the dielectric slab, wherein a connecting line between the first feed-in point and a rotational symmetry center (O) of the radiation loop is perpendicular to a connecting line between the second feed-in point and the rotational symmetry center of the radiation loop, a plurality of bends (100w') arched from a body of the radiation loop toward the dielectric slab are formed at predetermined positions along the circumference of the radiation loop, the body (100b1) of the radiation loop extends along a hypothetical planar base ring (BC), the plurality of bends form a part of the layout of the radiation loop, bottoms of the plurality of bends extend in a plane at a predetermined distance from and substantially parallel to the dielectric slab, and the sizes and positions of the plurality of bends are designed such that the parallel capacitive loading is introduced between the bottoms of the bends and the dielectric slab and the parallel capacitive loading introduced enables the resonance of a main mode of the radiation loop within a designed band of the band control unit.

2. The antenna assembly according to claim 1 , wherein the plurality of bends each have two opposite vertical walls and a horizontal bottom.

3. The antenna assembly according to claim 1 or 2, wherein the body of the radiation loop extends along a square hypothetical planar base ring, and the first feed-in point and the second feed-in point of the radiation loop are provided on the body of the radiation loop and at center points of two adjacent sides of the base ring, respectively.

4. The antenna assembly according to claim 3, wherein the number of the bends having projections on a side of the base ring where the first feed-in point or the second feed-in point is located is an even number, and the bends are arranged to be symmetrical about a vertical symmetrical plane passing through the center point of the corresponding side.

5. The antenna assembly according to claim 1 or 2, wherein the antenna assembly (1") comprises two band control units adaptable to different bands, wherein a radiation loop (100"-1 ) of a first band control unit (10"-1 ) and a radiation loop (100"-2) of a second band control unit (10"-2) are concentrically disposed above the dielectric slab (12).

6. The antenna assembly according to claim 5, wherein the radiation loop (100"-1 ) of the first band control unit (10"-1 ) and the radiation loop (100"-2) of the second band control unit (10"-2) are similar in shape and coincide in the plane of symmetry, and the radiation loop of the first band control unit is disposed at a predetermined distance to the inner side of the radiation loop of the second band control unit.

7. The antenna assembly according to claim 6, wherein a plane where a body(100b"-1 ) of the radiation loop of the first band control unit is located coincides with a plane where a body (100b"-2) of the radiation loop of the second band control unit is located, and a plane where the bottoms of the bends of the radiation loop of the first band control unit are located coincides with a plane where the bottoms of the bends of the radiation loop of the second band control unit are located.

8. The antenna assembly according to claim 6 or 7, wherein a hypothetical planar base ring of the radiation loop of the first band control unit and a hypothetical planar base ring of the radiation loop of the second band control unit are square, a first feed-in point (F1 -1 ) and a second feed-in point (F2-1 ) of the radiation loop of the first band control unit are respectively provided on the body of the radiation loop of the first band control unit, a first feed-in point (F1-2) and a second feed-in point (F2-2) of the radiation loop of the second band control unit are respectively provided on the body of the radiation loop of the second band control unit, the hypothetical planar base rings of the two radiation loops have two common diagonals (k1 , k2), the first feed-in point and the second feed-in point of the radiation loop of the first band control unit are symmetrically provided, about the first diagonal (k1 ) of the two common diagonals, at center points of two adjacent sides of the hypothetical planar base ring (BC-1 ) of the radiation loop of the first band control unit, respectively, the first feed-in point and the second feed-in point of the radiation loop of the second band control unit are symmetrically provided, about the first diagonal, at center points of two adjacent sides of the hypothetical planar base ring (BC-2) of the radiation loop of the second band control unit respectively, the first feed-in point and the second feed-in point of the radiation loop of the first band control unit and the first feed-in point and the second feed-in point of the radiation loop of the second band control unit are provided at different sides of the second diagonal (k2) of the two common diagonals.

9. The antenna assembly according to claim 1 or 2, wherein the antenna assembly comprises three or more band control units, the radiation loops of the respective band control units are concentrically disposed above the dielectric slab, two adjacent radiation loops are spaced apart by a predetermined distance, the radiation loops of all of the band control units have a similar shape and coincide in the plane of symmetry, planes where the radiation loops of all of the band control units are located coincide, and planes where the bottoms of the bends of the radiation loops of all of the band control units are located coincide.

10. The antenna assembly according to claim 1 or 2, wherein the first feed structure (100T) and the second feed structure (1002') realize the feeding of the radiation loop (100') in a coupled feed manner.

11. The antenna assembly according to claim 10, wherein the first feed structure (100T) and / or the second feed structure (1002') have vertical posts (1001 '-1a, 1002'-1 a; 1001'-1 b, 1002'-1 b; 1001'-1c, 1002'-1 c) and transverse coupling portions (1001 '-2a, 1002'-2a; 1001 '-2b, 1002'-2b; 1001 '-2c, 1002'-2c), which are substantially formed in a T or L shape.

12. The antenna assembly according to claim 11 , wherein the transverse coupling portions have coupled feed surfaces (100T -CF; 1 OO2'-CF) facing the lower side of the body of the radiation loop.

13. The antenna assembly according to claim 1 or 2, wherein the radiation loop is an integrally molded metal ring.

14. The antenna assembly according to claim 1 or 2, wherein the dielectric slab(12) is a printed circuit board (PCB).

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