Antenna assembly

Abstract

The present invention relates to an antenna assembly, comprising an upper dielectric slab and a lower dielectric slab stacked one above another and spaced apart, a ground plane being disposed on the lower dielectric slab. The antenna assembly comprises a band control unit, the band control unit comprises a first feeder line and a second feeder line that are disposed on the lower dielectric slab and a radiation loop disposed on the upper dielectric slab and having a geometrical shape in rotational symmetry. The first feeder line and the second feeder line are connected to a first feed-in point and a second feed-in point of the radiation loop via a first feed structure and a second feed structure, respectively, to feed the radiation loop. A connecting line between the first feed-in point and a center of the radiation loop is perpendicular to a connecting line between the second feed-in point and the center of the radiation loop. The band control unit further comprises multiple sets of parasitic branches, each set of parasitic branches is short-circuited to the ground plane, and the multiple sets of parasitic branches are arranged to form a closely coupled electric field in combination with the radiation loop.

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 GNSS (Global Navigation Satellite System) satellite positioning are dual-band ceramic patch antennas. Such antennas are composed of two thick ceramic blocks stacked one above another, and there is a height difference between the equivalent phase centers of two frequency points in a vertical direction, which is not conducive to meeting the requirement for the dual-band phase center consistency of a high-precision satellite positioning system. Surfaces of the upper and lower ceramic blocks are plated with multiple layers of metal coatings, and the metal coatings are coupled with each other, resulting in interference between two operating frequency points and difficulty in independent debugging.

[0008] In addition, in the design process of existing vehicle-mounted antennas (such as dual-band dual-feed circularly polarized satellite antennas), there are also such technical problems: dual-band phase centers of the satellite positioning system are not consistent in the height direction; an antenna radiation field is easy to be interfered with by the external environment, resulting in degradation of the antenna transmission performance; for a dual-band antenna, radiation structures of two bands will produce unnecessary coupling, which leads to interference between radiation fields of the two bands and makes it difficult to carry out independent design for the radiation structure of each band; the antenna profile is high and unfavorable for assembly; the multi-band antenna integration has insufficient isolation and strong signal crosstalk; and costs for antenna research and development and manufacturing are high, and the like.

[0009] The present invention is intended to solve one or more problems of the existing antennas.

[0010] Summary of the Invention

[0011] With an antenna assembly according to the present invention, it is possible to provide a high-precision GNSS satellite positioning vehicle-mounted circularly polarized antenna. The performance and the structure of the high-precision vehicle-mounted satellite positioning antenna is optimized, and it is possible to provide an antenna with a single band or dual bands (e.g., dual bands of GNSS L1 (1 .559-1 .606 GHz), GNSS L5 (1 .166-1 .192 GHz)) or more bands and having low profile, high compactness and superior positioning performance.

[0012] In view of this, according to an aspect of the present invention, provided is an antenna assembly, which is characterized by comprising an upper dielectric slab and a lower dielectric slab stacked one above another and spaced apart, a ground plane being disposed on the lower dielectric slab, wherein the antenna assembly comprises a band control unit, the band control unit comprises a first feeder line and a second feeder line that are disposed on the lower dielectric slab and a radiation loop disposed on the upper dielectric slab and having a geometrical shape in rotational symmetry, the first feeder line and the second feeder line are connected to a first feed-in point and a second feed-in point of the radiation loop via a first feed structure and a second feed structure, respectively, to feed the radiation loop, a connecting line between the first feed-in point and a center of the radiation loop is perpendicular to a connecting line between the second feed-in point and the center of the radiation loop, and the band control unit further comprises multiple sets of parasitic branches disposed on the upper dielectric slab, each set of parasitic branches is short-circuited to the ground plane, the multiple sets of parasitic branches are distributed at intervals on a hypothetical parasitic ring that encircles a vertical axis passing through the center of the radiation loop and extends along and adjacent to the radiation loop, so that the radiation loop is combined with the parasitic branches to form a closely coupled electric field.

[0013] The antenna assembly according to the present invention has a planar-loop antenna structure and adopts a GNSS single-band dual-feed circularly polarized antenna architecture. The radiation loop adopts independent feed ports coupled in an orthogonal direction, and the unique electric field zero-pole distribution characteristic improves isolation between two orthogonal feed ports in the same band. In addition, by the closely coupled electric field formed between the radiation loop and the parasitic branches, the antenna assembly may form an inwardly coupled binding field, which reduces interference from the external environment. In addition, based on this antenna architecture, high-precision dual-band / multi-band antenna assembles may be extended according to requirements of different satellite positioning bands.

[0014] Preferably, the radiation loop is square and the first feed-in point and the second feed-in point of the radiation loop are provided at center points of two adjacent sides of the radiation loop, respectively.

[0015] Preferably, the multiple sets of parasitic branches include four sets of parasitic branches, the four sets of parasitic branches are respectively disposed at positions, adjacent to four comers of the radiation loop, on the parasitic ring, and each set of parasitic branches includes branch legs extending parallel to two adjacent sides of the radiation loop.

[0016] Preferably, the multiple sets of parasitic branches and the radiation loop are located in the same plane.

[0017] Preferably, the parasitic ring is disposed on the inner side of the radiation loop.

[0018] Preferably, the band control unit further comprises an adjusting branch disposed on the upper dielectric slab and used for adjusting the antenna performance, the adjusting branch extending from the radiation loop to the center of the radiation loop.

[0019] Preferably, the antenna assembly comprises two band control units, wherein a radiation loop of a first band control unit and a radiation loop of a second band control unit are concentrically and coplanarly disposed on the upper dielectric slab, the radiation loop of the first band control unit and the radiation loop of the second band control unit are similar in shape, coincide in the axis of symmetry and are separated by a predetermined distance.

[0020] Preferably, the applicable frequency of the first band control unit is higher than the applicable frequency of the second band control unit, a hypothetical parasitic ring of the first band control unit is provided in the same plane as the radiation loop of the first band control unit and is located on the inner side of the radiation loop of the first band control unit, and a hypothetical parasitic ring of the second band control unit is provided in the same plane as the radiation loop of the second band control unit and is located on the outer side of the radiation loop of the second band control unit.

[0021] Preferably, the radiation loop of the first band control unit and the radiation loop of the second band control unit are square, the two radiation loops have two common diagonals, a first feed-in point and a second feed-in point of the radiation loop of the first band control unit are symmetrically provided, about a first diagonal of the two common diagonals, at center points of two adjacent sides of the radiation loop of the first band control unit, respectively, a first feed-in point and a 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 radiation loop of the second band control unit, respectively, and 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 located at different sides of a second diagonal of the two common diagonals.

[0022] Preferably, parasitic branches of the first band control unit include four sets of first parasitic branches respectively disposed at positions, adjacent to four comers of the radiation loop of the first band control unit, on the parasitic ring on the inner side of the radiation loop of the first band control unit, and each set of first parasitic branches includes branch legs extending parallel to two adjacent sides of the radiation loop.

[0023] Preferably, parasitic branches of the second band control unit include four sets of second parasitic branches respectively disposed at positions, adjacent to four comers of the radiation loop of the second band control unit, on the parasitic ring on the outer side of the radiation loop of the second band control unit, and each set of second parasitic branches includes branch legs extending parallel to two adjacent sides of the radiation loop.

[0024] Preferably, the first band control unit comprises at least a pair of first adjusting branches symmetrically disposed on the diagonal, extending from the radiation loop of the first band control unit towards the center of the radiation loop of the first band control unit, and arranged on the upper dielectric slab, and / or the second band control unit comprises at least a pair of second adjusting branches symmetrically disposed on the diagonal, extending from the radiation loop of the second band control unit towards the center of the radiation loop of the second band control unit, and arranged on the upper dielectric slab.

[0025] Compared with the existing dual-band antenna assembly, 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), and may be flexibly integrated into the car body plane design to constitute the vehicle-mounted hidden satellite positioning antenna system. 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. Signals of different bands will have different phase delays in the propagation process, and accordingly, 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. According to the design structure of the dual-band antenna assembly of the present invention, the centers of the two radiation loops corresponding to two different GNSS operating frequency points 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 an inwardly coupled binding field, which reduces the coupling with radiation loops of other frequency points and facilitates the independent design of dual bands.

[0026] Preferably, the antenna assembly comprises three or more said band control units, radiation loops of the band control units are coplanarly and concentrically disposed on the upper dielectric slab, two adjacent radiation loops are separated by a predetermined distance, and the radiation loops of all the band control units are similar in shape and coincide in the axis of symmetry.

[0027] Preferably, the upper dielectric slab is supported on the lower dielectric slab by means of at least one supporting structure.

[0028] Preferably, the at least one supporting structure comprises metal posts for connecting the parasitic branches of the band control unit to the ground plane of the lower dielectric slab.

[0029] Preferably, a hollow structure is formed at the center of the upper dielectric slab.

[0030] Preferably, the upper dielectric slab and the lower dielectric slab are printed circuit boards (PCBs).

[0031] The antenna assembly according to the present invention may be used as a hidden vehicle-mounted 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, and accordingly they can be widely applied to vehicles and other means of transportation. In addition, the circularly polarized antenna assembly according to the present invention integrates single or dual or multiple operating bands for GNSS vehicle-mounted satellite positioning. Moreover, the circularly polarized antenna assembly has the low-profile structural characteristic, may be flexibly integrated into the car body plane design, has a more desirable equivalent phase center consistency, and improves the performance of the high-precision satellite positioning system. Moreover, the manufacturing process based on PCBs is simple, the manufacturing cost is low, and mass production is facilitated.

[0032] Brief Description of the Drawings

[0033] 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.

[0034] FIG. 1 shows a perspective diagram of an antenna assembly according to a first embodiment of the present invention;

[0035] FIG. 2 shows a side sectional view of the antenna assembly according to the first embodiment of the present invention;

[0036] FIG. 3 shows a schematic diagram of an electric field excited by a feed port of the antenna assembly according to the first embodiment of the present invention; FIG. 4 shows a variation of the arrangement of a first feed-in point and a second feed-in point in the antenna assembly according to the first embodiment of the present invention;

[0037] FIG. 5 shows a variation of the feeder line arrangement of the antenna assembly according to the first embodiment of the present invention;

[0038] FIG. 6 shows an S-parameter curve diagram of the antenna assembly according to the first embodiment of the present invention;

[0039] FIG. 7 shows an axial ratio diagram of the antenna assembly according to the first embodiment of the present invention;

[0040] FIG. 8 shows a radiation gain diagram of the antenna assembly according to the first embodiment of the present invention;

[0041] FIG. 9 shows a perspective diagram of an antenna assembly according to a second embodiment of the present invention;

[0042] FIG. 10 shows a schematic plan of the antenna assembly according to the second embodiment of the present invention; and

[0043] FIG. 11 shows an S-parameter curve diagram of the antenna assembly according to the second embodiment of the present invention.

[0044] Detailed Description of the Invention

[0045] 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.

[0046] The antenna assembly according to the present invention has substantially a planar loop antenna structure, is implemented on the basis of dielectric slabs such as PCBs, has a small overall side height, and may be flexibly integrated into the car body plane design to constitute a vehicle-mounted hidden satellite positioning antenna system.

[0047] First embodiment of the antenna

[0048] FIGS. 1 and 2 show an antenna assembly T according to a first embodiment of the present invention. The antenna assembly T comprises an upper dielectric slab 11 and a lower dielectric slab 12 stacked one above another and spaced apart. The upper dielectric slab is, for example, supported on the lower dielectric slab by means of a supporting structure. In the advantageous embodiment shown in FIG. 1 , both the upper dielectric slab 11 and the lower dielectric slab 12 are implemented as PCBs. Preferably, the upper dielectric slab is parallel to the lower dielectric slab.

[0049] The antenna assembly T according to the embodiment comprises a band control unit 10' configured to control the performance of the antenna assembly in a particular band. The band control unit 10’ comprises a first feeder line 10T and a second feeder line 102' that are disposed on the lower dielectric slab 12 and a radiation loop 103' disposed on the upper dielectric slab 11 and having a geometrical shape in rotational symmetry. The radiation loop 103' is etched on a planar side (e.g., bottom plane) of the upper dielectric slab 11 . The first feeder line 10T and the second feeder line 102' are connected to the radiation loop 103' via a first feed structure 101T and a second feed structure 102T respectively to feed the radiation loop. In the illustrated embodiment, the first feed structure 101T and the second feed structure 102T are spaced from the radiation loop 103' by a certain distance to perform coupled feed to the radiation loop 103'. The first feed structure 101T includes a coupling metal post M1 connected to the first feeder line 10T and a patch P1 disposed on the top of the coupling metal post M1 and spaced apart from the radiation loop 103' in a vertical direction. The second feed structure 102T includes a coupling metal post M2 connected to the second feeder line 102' and a patch P2 disposed on the top of the coupling metal post M2 and spaced apart from the radiation loop 103' in the vertical direction. The patches are preferably circular. Projection positions of the patches of the first feed structure and the second feed structure in the vertical direction on the radiation loop may be regarded as a first feed-in point F1 and a second feed-in point F2 of the radiation loop.

[0050] In the embodiment shown in FIG. 1 , a connecting line between the first feed-in point F1 of the radiation loop 103' and a center O of the radiation loop 103' is perpendicular to a connecting line between the second feed-in point F2 and the center O of the radiation loop, 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.

[0051] A metal layer (e.g., copper) covering the entire bottom surface of the lower dielectric slab 12 is implemented as a ground plane 12b, i.e., as the ground for the first feeder line and the second feeder line and for the radiation loop. Although the ground plane 12b is shown to be located at the bottom of the lower dielectric slab, it can be understood that the ground plane may be provided as other layers of the lower dielectric slab. For example, the ground plane 12b may be disposed on the upper layer of the lower dielectric slab, and, accordingly, the first feeder line and the second feeder line may be disposed on the bottom layer of the lower dielectric slab.

[0052] The band control unit 10' further comprises multiple sets of parasitic branches 104'p disposed on the upper dielectric slab. Each set of parasitic branches is short-circuited to the ground plane 12b. The multiple sets of parasitic branches are distributed at intervals on a hypothetical parasitic ring C that encircles a vertical axis passing through the center of the radiation loop and extends along and adjacent to the radiation loop, so that the radiation loop is combined with the parasitic branches to form a closely coupled electric field. In the embodiment shown in FIG. 1 , the multiple sets of parasitic branches 104'p and the radiation loop 103' are disposed in the same plane of the upper dielectric slab. In an advantageous embodiment, the parasitic ring C where the parasitic branches are located is provided on the inner side of the radiation loop 103'.

[0053] Although the figure shows that the multiple sets of parasitic branches are disposed on the top side of the upper dielectric slab where the radiation loop is located, it can be understood that the multiple sets of parasitic branches may be disposed on a different layer of the upper dielectric slab than the top side, for example, disposed on the bottom side of the upper dielectric slab.

[0054] In the illustrated embodiment, the radiation loop 103' is substantially square in shape. The first feed-in point and the second feed-in point of the radiation loop are provided at center points of two adjacent sides of the square radiation loop, respectively. A set of parasitic branches 10-4'p is placed at a position, adjacent to each of four corners of the square radiation loop, on the parasitic ring. Each set of parasitic branches includes branch legs 104'p1 , 1O4'p2 extending parallel to two adjacent sides of the radiation loop. The joint (i.e. , right angle) of the two branch legs is short-circuited to the ground plane 12b of the lower dielectric panel 12 through a parasitic metal post 104'c.

[0055] These short-circuit parasitic branches 104'p arranged on the parasitic ring are typically used for improving the radiation performance of the antenna, for example, adjusting the impedance matching or controlling the polarization direction of radiation of the antenna. In the configuration shown in FIG. 1 , the parasitic branch 104'p and the square radiation loop 103' form the closely coupled electric field such that a fringing field of the square radiation loop is bound inwardly under the influence of the short-circuited grounded parasitic branches, thus reducing the outward diffusion of the fringing field, and reducing the interference from the external environment to this square radiation loop.

[0056] In the embodiment shown in FIG. 1 , a hollow structure 13 is formed at the center of the upper dielectric slab 11 . The hollow structure may be formed, for example, by scooping a portion from the center of the upper dielectric slab.

[0057] Generally, on the upper dielectric slab 11 , the square radiation loop is combined with the parasitic branches at the four corners of the parasitic ring to form a horizontally rotational symmetry structure using the normal direction (perpendicular to the upper dielectric slab) of the center of the upper dielectric slab as an axis, thus ensuring that equal-amplitude orthogonal linearly polarized components are generated at the first feed-in point F1 and the second feed-in point F2 in a direction orthogonal to the first feed-in point by 90° so as to facilitate the forming of a circularly polarized radiation beam in space.

[0058] Specifically, as shown in FIG. 3, the antenna assembly T may generate an electric field zero-pole distribution similar to that in the form of a microstrip patch antenna. Through the cooperation between the first feeder line 10T and the first feed structure 1011', the square radiation loop 103' and the copper-coated surfaces of the coupled short-circuited parasitic branches at the four corners on the parasitic ring C are combined to form an electric field distribution pattern with the strongest electric field on two sides and the weakest electric field at the center. Moreover, in this electric field operating pattern, the weakest point of the electric field strength is just at a feed position of the second feeder line 102' and the second feed structure 102T, while the coupling metal posts perform coupled feed to the radiation loop via the circular patches disposed above, thereby forming a high isolation of dual 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.

[0059] 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 the two adjacent sides of the square radiation loop, respectively, it can be understood that the first feed-in point F1 and the second feed-in point F2 may also be located out of the center positions of the two adjacent sides of the square radiation loop, provided that the connecting line between the first feed-in point F1 and the center of the radiation loop is perpendicular to the connecting line between the second feed-in point F2 and the center of the radiation loop, for example, as shown in FIG. 4.

[0060] The specific circular polarization implementation process may also be shown, for example, in FIG. 5, where a one-into-two circuit of a 90° phase shifter is etched on an upper surface of the lower dielectric slab 12, the first feeder line and the second feeder line are specifically implemented as two transmission lines L1 , L2 that are unequal in length and are connected to the phase shifter, and the transmission lines L1 , L2 feed energy through a single port 105.

[0061] Referring to FIGS. 6-8, it can be seen that the single-band circular polarization performance of the antenna assembly T according to this embodiment is improved. As shown in FIG. 6, the impedance bandwidth of -10 dB enables an operating bandwidth of 50 MHz from 1.56 GHz to 1 .61 GHz. As shown in FIG. 7, the axial ratio bandwidth of 3 dB may meet the operating requirement of the GNSS L1 band. As shown in FIG. 8, the maximum circularly polarized radiation gain reaches 3 dBiC, which may improve the transmission signal quality of the satellite positioning system.

[0062] Referring to FIG. 1 , the band control unit 10' further comprises an adjusting branch 106' disposed on the upper dielectric slab and used for adjusting the antenna performance, the adjusting branch extending from the radiation loop towards the center of the radiation loop. In the embodiment shown in FIG. 1 , the adjusting branch 106' refers to a pair of branches disposed on a diagonal of the square radiation loop. The first feed-in point F1 and the second feed-in point F2 are located at two sides of the diagonal where the adjusting branch 106' is located, respectively. The antenna performance may be fine-tuned or optimized by adjusting the length of the adjusting branch.

[0063] Although it is shown in FIG. 1 that in the antenna assembly T according to the first embodiment of the present invention, the parasitic ring C is located on the inner side of the radiation loop 103', it can be understood that the parasitic ring (i.e. , the parasitic branches) may also be provided on the outer side of the radiation loop.

[0064] Although in the embodiment shown in FIG. 1 , the radiation loop is subjected to coupled feed at the first feed-in point and the second feed-in point, it can be understood that the radiation loop may also be directly fed, for example, upper ends of the coupling metal posts may be electrically connected to the radiation loop by welding.

[0065] Second embodiment of the antenna assembly

[0066] 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.

[0067] Referring to FIGS. 9 and 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 10' in the first embodiment of the present invention.

[0068] That is, the first band control unit 10"-1 has a radiation loop 103"-1 , a first feeder line 101"-1 and a second feeder line 102"-1 used for performing coupled feed to the corresponding radiation loop, and parasitic branches 104"p-1 configured to form a closely coupled electric field with the corresponding radiation loop. The first feeder line 101"-1 of the first band control unit 10"-1 performs coupled feed to the radiation loop 103"-1 via a coupling metal post M1 -1 at a first feed-in point F1 -1. The second feeder line 102"-1 of the first band control unit 10"-1 performs coupled feed to the radiation loop 103"-1 via a coupling metal post M2-1 at a second feedin point F2-1. The second band control unit 10"-2 has a radiation loop 103"-2, a first feeder line 101 "-2 and a second feeder line 102"-2 used for performing coupled feed to the corresponding radiation loop, and parasitic branches 104"p-2 configured to form a closely coupled electric field with the corresponding radiation loop. The first feeder line 101 "-2 of the second band control unit 10"-2 performs coupled feed to the radiation loop 103"-2 via a coupling metal post M1-2 at a first feed point F1-2. The second feeder line 102"-2 of the second band control unit 10"-2 performs coupled feed to the radiation loop 103"-2 via a coupling metal post M2-2 at a second feed point F2-2.

[0069] The radiation loop 103"-1 of the first band control unit 10"-1 and the radiation loop 103"-2 of the second band control unit 10"-2 are concentrically and coplanarly disposed on the upper dielectric slab 11 , the radiation loop of the first band control unit and the radiation loop of the second band control unit are similar in shape, coincide in the axis of symmetry and are separated by a predetermined distance.

[0070] In the embodiment of the dual-band loop antenna shown in FIGS. 9 and 10, the first band control unit 10"-1 having the radiation loop 103"-1 on the inner side is a high-band control unit. The second band control unit 10"-2 having the radiation loop 103"-2 on 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. The radiation loop 103"-1 of the high-band control unit and the radiation loop 103"-2 of the low-band control unit are square. A hypothetical parasitic ring C-1 where the parasitic branches of the high-band control unit are located and a hypothetical parasitic ring C-2 where the parasitic branches of the low-band control unit are located are correspondingly designed into a square shape. In the embodiment shown in FIGS. 9 and 10, the hypothetical parasitic ring C-1 (or corresponding parasitic branches) of the high-band control unit and the radiation loop 103"-1 of the high-band control unit are provided in the same plane. The hypothetical parasitic ring C-2 (or corresponding parasitic branches) of the low- band control unit and the radiation loop 103"-2 of the low-band control unit are provided in the same plane. The parasitic ring C-1 of the high-band control unit is provided on the inner side of the radiation loop 103"-1 of the high-band control unit. The parasitic ring C-2 of the low-band control unit is provided on the outer side of the radiation loop 103"-2 of the low-band control unit. The square radiation loops 103"-1 , 103"-2 are combined with multiple sets of parasitic branches 104"p- 1 , 104"p-2 of the corresponding bands that are placed at four right angles on adjacent square parasitic rings to form corresponding band control parts. Each set of parasitic branches 104"p-1 of the high-band control unit includes branch legs 104"p1-1 , 104"p2-1 extending parallel to two adjacent sides of the corresponding radiation loop 103"-1. Each set of parasitic branches 104"p-2 of the low-band control unit includes branch legs 104"p1-2, 104"p2-2 extending parallel to two adjacent sides of the radiation loop 103"-2.

[0071] The two radiation loops 103"-1 , 103"-2 have two common diagonals k1 , k2, a first feed-in point F1-1 and a second feed-in point F2-1 of the radiation loop of the high- band control unit are symmetrically provided, about a first diagonal k1 of the two common diagonals, at center points of two adjacent sides of the radiation loop 103"-1 of the high-band control unit respectively, a first feed-in point F1-2 and a second feed-in point F2-2 of the radiation loop of the low-band control unit are symmetrically provided, about the first diagonal k1 , at center points of two adjacent sides of the radiation loop 103"-2 of the low-band control unit respectively, and the first feed-in point F1-1 and the second feed-in point F2-1 of the radiation loop 103"-1 of the high-band control unit and the first feed-in point F1-2 and the second feed-in point F2-2 of the radiation loop 103"-2 of the low-band control unit are located at different sides of a second diagonal k2 of the two common diagonals.

[0072] In the low-band control unit, each set of low-band parasitic branch 104"p-2 is short-circuited to the ground plane 12b of the lower dielectric slab 12, at the joint (right angle at a turn) of the branch legs 104"p1-2, 104"p2-2, via a parasitic metal post 104"c-2, and the square radiation loop 103"-2 on the periphery is combined with multiple sets of low-band parasitic branches 104"p-2 placed at four right angles on the adjacent square parasitic ring to form a closely coupled electric field, which confines the fringing field of the square radiation loop on the periphery.

[0073] In the high-band control unit, each set of high-band parasitic branch 104"p-1 is short-circuited to the ground plane 12b of the lower dielectric slab 12, at the joint (right angle at a turn) of the branch legs 104"p1 -1 , 104"p2-1 , via a parasitic metal post 104"c-1 , and the square radiation loop 103"-1 on the inner side is combined with multiple sets of high-band parasitic branches 104"p-1 placed at four right angles on the adjacent square parasitic ring to form a closely coupled electric field, which confines the fringing field of the square radiation loop on the inner side.

[0074] That is, without affecting the design of the square radiation loop 103"-1 of the high- band control unit (e.g., the satellite positioning band of GNSS L1 (1.559-1.606 GHz)), the square radiation loop 103"-2 with a large size that is disposed on the periphery of the square radiation loop 103"-1 on the upper dielectric slab 11 as well as the corresponding matching short-circuited parasitic branches 104"p-2 facilitates the addition of the low-band control unit (e.g., the satellite positioning band of GNSS L5 (1 .166-1 .192 GHz)) on the same pair of dielectric slabs. The radiation loops of the two band control units have no distance difference in the height direction, thus ensuring the phase center consistency for high-precision satellite positioning.

[0075] In addition, the closely coupled short-circuited parasitic branches 104"p-1 , 104"p-2 disposed adjacent to the radiation loops 103"-1 , 103"-2 of the two band control units ensure that the fringing fields of the radiation loops of the two band control units are bound inwardly, which not only reduces the coupling between the radiation loops of the two band control units and facilitates the independent design of dual bands, but also confines the outward coupling, and reduces the influence from the external environment. Moreover, the radiation loops of the two bands control unit adopt the electric field operating pattern at their operating frequency points as shown in FIG. 3, and a similar zero-pole electric field distribution pattern may be formed in both bands, thereby naturally isolating the dual feed points in dual bands and reducing the dual-band dual-feed coupling. The overall dual-loop structure presents a symmetrical characteristic, ensuring that two equal-amplitude orthogonal polarization components are generated via the orthogonal ports in two bands, and facilitating the generation of a dual-band circularly polarized beam.

[0076] In the embodiment shown in FIG. 9, the high-band control unit comprises a pair of first adjusting branches 106"-1 disposed on the upper dielectric slab 11 , the first adjusting branches extending from the radiation loop of the high-band control unit towards the center of the radiation loop 103"-1 of the high-band control unit. The first adjusting branches are symmetrically provided on the first diagonal k1 . The low-band control unit comprises a pair of second adjusting branches 106"-2 provided on the upper dielectric slab 11 , the second adjusting branches extending from the radiation loop of the low-band control unit towards the center of the radiation loop 103"-2 of the low-band control unit. The second adjusting branches are symmetrically provided on the first diagonal k1 . The first adjusting branches and the second adjusting branches are configured to fine-tune and optimize the antenna performance.

[0077] Although in the embodiment shown in FIG. 9, the high-band control unit of the antenna assembly according to the second embodiment of the present invention comprises only one pair of the first adjusting branches and the low-band control unit comprises only one pair of the second adjusting branches, it can be understood that the high-band control unit may comprise two pairs of the first adjusting branches disposed on the first and the second diagonals respectively and having unequal length, and the low-band control unit may comprise two pairs of the first adjusting branches disposed on the first and the second diagonals respectively and having unequal length. The adjusting branches are arranged in this way such that a perturbation effect can be produced, which achieves the purpose of adjusting and optimizing the frequency.

[0078] The operating performance of the dual-band dual-loop antenna is shown in FIG. 11 . By fine-tuning the adjusting branches extending from the two radiation loops, the resonant band can be improved and the requirements for the impedance bandwidth of the dual-band GNSS can be satisfied.

[0079] In the antenna assembly 1" according to the second embodiment of the present invention, the loop planar antenna architecture is beneficial to the independent development of dual-band dual-feed circularly polarized GNSS satellite positioning antenna. The integrated dual-band planar design is conducive to meeting the requirement for high-precision satellite positioning with consistent phase centers. 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 fringing fields of two operating bands both have the inward binding characteristic, which not only reduces the coupling between the radiation loops of the two bands, facilitates the characteristic of independent work of the two bands, but also confines the outward coupling and reduces the influence from the external environment.

[0080] Multi-band antenna assembly according to the present invention

[0081] 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, radiation loops of the band control units are coplanarly and concentrically disposed on the upper dielectric slab, two adjacent radiation loops are separated by a predetermined distance, and the radiation loops of all the band control units are similar in shape and coincide in the axis of symmetry.

[0082] Although the parasitic branches and the radiation loops are disposed in the same plane in the embodiment of the present invention shown in FIGS. 1 and 9, it can be understood that the radiation loop and the corresponding parasitic branches in the same band control unit may be disposed in different layers of the upper dielectric slab. For example, the radiation loop in the high-band control unit is disposed on the upper layer of the upper dielectric slab, while the corresponding parasitic branch or parasitic branch ring is provided on the lower layer of the upper dielectric slab. Alternatively, the radiation loop in the high-band control unit is disposed on the lower layer of the upper dielectric slab, and the corresponding parasitic branch or parasitic branch ring is located on the upper layer of the upper dielectric slab. Similarly, the radiation loop in the low-band control unit and the corresponding parasitic branches may be disposed on different layers of the upper dielectric slab. Preferably, the radiation loop in the high-band control unit and the radiation loop in the low-band control unit are disposed in the same plane on the upper dielectric slab to ensure that the phase center consistency for high-precision satellite positioning is always obtained.

[0083] The multi-band antenna assembly according to the present invention has the ultralow profile characteristic and small-sized loop planar antenna structure, may be flexibly integrated into the car body plane design, and is adaptable to the vehiclemounted 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 short- circuited parasitic branches so as to obtain a multi-band multi-feed antenna structure, thereby expanding the band applicable range of the antenna assembly, and making it possible to integrate the control parts of multiple bands on the same pair of dielectric slabs, which further improves the compactness and integration of the antenna assembly. In addition, the radiation loops of all the band control units are 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, the radiation loops of different bands and the corresponding short-circuited parasitic branches form the unique design of an inward binding field, which is conducive to reducing the influences from the band control parts and the external environment to the antenna system.

[0084] 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. Accordingly, the parasitic branches on the parasitic ring adjacent to the radiation loop and belonging to the same band control unit are closely coupled to the radiation loop, which may also bind the ring fringing field inwardly to reduce the coupling with the external environment. 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. In combination with the coupled feed, this zero-pole electric field distribution pattern greatly reduces the coupling between the feed ports. The symmetrical characteristic of the overall ring-shaped radiation structure guarantees two orthogonal polarized components of equal amplitude, which facilitates the generation of a circularly polarized beam (e.g. circularly polarized satellite positioning beam).

[0085] The antenna assemblies T, 1" according to the present invention are preferably implemented on the basis of the processing of PCBs. The upper PCB is supported on the lower PCB by means of a supporting structure. The supporting structure may comprise parasitic metal posts 104'c, 104"c-1 , 104"c-2 for connecting the parasitic branches 104'p, 104"p-1 , 104"p-2 of the band control units 10', 10"-1 , 10"-2 to the ground plane 12b of the lower PCB. This makes the manufacturing process of the antenna assembly according to the present invention simple and the manufacturing cost further reduced.

[0086] In summary, the antenna assembly according to the present invention is capable of achieving at least one of the following advantages:

[0087] Structural characteristics: It has a hidden low-profile antenna architecture, and the planar integrated single-band / dual-band / multi-band structure is small in size and is compact.

[0088] Electrical characteristics: 3dBiC circularly polarized radiation gain improves the quality of the satellite positioning system; the unique electric field zero-polar distribution and unique coupled feeding form high isolation of dual feed ports; flexible multi-port multi-band independent design and development and the expansion of communication band are achieved; in addition, for the dual-band or multi-band antenna architecture, it is ensured that the high phase center consistency meets the requirement of high-precision GNSS satellite positioning.

[0089] Engineering characteristics: The manufacturing cost is low, the manufacturing process is simple, the coupled internal field is not easy to be affected by the external assembly environment, and mass production is facilitated.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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 an upper dielectric slab (11 ) and a lower dielectric slab (12) stacked one above another and spaced apart, a ground plane (12b) being disposed on the lower dielectric slab (12), wherein the antenna assembly (1 ') comprises a band control unit (10'), the band control unit comprises a first feeder line (101 ') and a second feeder line (102') that are disposed on the lower dielectric slab (12) and a radiation loop (103') disposed on the upper dielectric slab (11 ) and having a geometrical shape in rotational symmetry, the first feeder line (101 ') and the second feeder line (102') are connected to a first feed-in point (F1 ) and a second feed-in point (F2) of the radiation loop (103') via a first feed structure (1011 ') and a second feed structure (1021 '), respectively, to feed the radiation loop (103'), and a connecting line between the first feed-in point and a center of the radiation loop is perpendicular to a connecting line between the second feed-in point and the center of the radiation loop, and the band control unit (10') further comprises multiple sets of parasitic branches (10-4'p) disposed on the upper dielectric slab (11 ), each set of parasitic branches is short-circuited to the ground plane (12b), the multiple sets of parasitic branches (10-4'p) are distributed at intervals on a hypothetical parasitic ring (C) that encircles a vertical axis passing through the center of the radiation loop (103') and extends along and adjacent to the radiation loop, so that the radiation loop is combined with the parasitic branches to form a closely coupled electric field.

2. The antenna assembly as claimed in claim 1 , wherein the radiation loop (103') is square and the first feed-in point and the second feed-in point of the radiation loop are provided at center points of two adjacent sides of the radiation loop, respectively.

3. The antenna assembly as claimed in claim 2, wherein the multiple sets of parasitic branches (10-4'p) comprise four sets of parasitic branches, the four sets of parasitic branches are disposed at positions, adjacent to four comers of the radiation loop, on the parasitic ring, respectively, and each set of parasitic branches comprises branch legs (104'p1 , 104'p2) extending parallel to two adjacent sides of the radiation loop.

4. The antenna assembly as claimed in claim 3, wherein the multiple sets of parasitic branches and the radiation loop (103') are located in the same plane.

5. The antenna assembly as claimed in claim 4, wherein the parasitic ring is disposed on the inner side of the radiation loop (103').

6. The antenna assembly as claimed in claim 1 , wherein the band control unit (10') further comprises an adjusting branch (106') disposed on the upper dielectric slab (11 ) and used for adjusting the antenna performance, the adjusting branch extending from the radiation loop (103') towardsthe center of the radiation loop.

7. The antenna assembly as claimed in claim 1 , wherein the antenna assembly (1") comprises two band control units, wherein a radiation loop (103"-1 ) of a first band control unit (10"-1 ) and a radiation loop (103"-2) of a second band control unit (10"-2) are concentrically and coplanarly disposed on the upper dielectric slab (11 ), the radiation loop of the first band control unit and the radiation loop of the second band control unit are similar in shape, coincide in the axis of symmetry and are separated by a predetermined distance.

8. The antenna assembly as claimed in claim 7, wherein the applicable frequencyof the first band control unit is higher than the applicable frequency of the second band control unit, a hypothetical parasitic ring (C-1 ) of the first band control unit is provided in the same plane as the radiation loop (103"-1 ) of the first band control unit and is located on the inner side of the radiation loop (103"-1 ) of the first band control unit, and a hypothetical parasitic ring (C-2) of the second band control unit is provided in the same plane as the radiation loop (103"-2) of the second band control unit and is located on the outer side of the radiation loop (103"-2) of the second band control unit.

9. The antenna assembly as claimed in claim 8, wherein the radiation loop of the first band control unit and the radiation loop of the second band control unit are square, the two radiation loops have two common diagonals (k1 , k2), a first feed-in point (F1 -1 ) and a second feed-in point (F2-1 ) of the radiation loop (103"-1 ) of the first band control unit are symmetrically provided, about a first diagonal (k1 ) of the two common diagonals, at center points of two adjacent sides of the radiation loop of the first band control unit, respectively, a first feed-in point (F1 -2) and a second feed-in point (F2-2) of the radiation loop (103"-2) of the second band control unit are symmetrically provided, about the first diagonal (k1 ), at center points of two adjacent sides of the radiation loop of the second band control unit, respectively, and the first feed-in point (F1 -1 ) and the second feed-in point (F2-1 ) of the radiation loop (103"-1 ) of the first band control unit and the first feed-in point (F1 -2) and the second feed-in point (F2-2) of the radiation loop (103"-2) of the second band control unit are located at different sides of a second diagonal (k2) of the two common diagonals.

10. The antenna assembly as claimed in claim 9, wherein parasitic branches(104"p-1 ) of the first band control unit comprise four sets of first parasitic branches respectively disposed at positions, adjacent to four corners of the radiation loop ofthe first band control unit, on the parasitic ring on the inner side of the radiation loop of the first band control unit, and each set of first parasitic branches comprises branch legs (104"p1-1 , 104"p2-1 ) extending parallel to two adjacent sides of the radiation loop.11 . The antenna assembly as claimed in claim 9, wherein parasitic branches (104"p-2) of the second band control unit comprise four sets of second parasitic branches respectively disposed at positions, adjacent to four corners of the radiation loop of the second band control unit, on the parasitic ring on the outer side of the radiation loop of the second band control unit, and each set of second parasitic branches comprises branch legs (104"p1-2, 104"p2-2) extending parallel to two adjacent sides of the radiation loop.

12. The antenna assembly as claimed in claim 9, wherein the first band control unit comprises at least a pair of first adjusting branches (106"-1 ) symmetrically disposed on the diagonal, extending from the radiation loop (103"-1 ) of the first band control unit towards the center of the radiation loop of the first band control unit, and arranged on the upper dielectric slab (11 ), and / or the second band control unit comprises at least a pair of second adjusting branches (106"-2) symmetrically disposed on the diagonal, extending from the radiation loop (103"-2) of the second band control unit towards the center of the radiation loop of the second band control unit, and arranged on the upper dielectric slab (11 ).

13. The antenna assembly as claimed in claim 1 , wherein the antenna assembly comprises three or more of band control units, radiation loops of the band control units are coplanarly and concentrically disposed on the upper dielectric slab, two adjacent radiation loops are separated by a predetermined distance, and the radiation loops of all the band control units are similar in shape and coincide in theaxis of symmetry.

14. The antenna assembly as claimed in any one of claims 1-13, wherein the upper dielectric slab (11 ) is supported on the lower dielectric slab (12) by means of at least one supporting structure.

15. The antenna assembly as claimed in claim 14, wherein the at least one supporting structure comprises metal posts (104'c, 104"c-1 , 104"c-2) for connecting the parasitic branches (104'p, 104"p-1 , 104"p-2) of the band control unit to the ground plane (12b) of the lower dielectric slab.

16. The antenna assembly as claimed in any one of claims 1-13, wherein a hollow structure (13) is formed at the center of the upper dielectric slab (11).

17. The antenna assembly as claimed in any one of claims 1 -13, wherein the upper dielectric slab (11 ) and the lower dielectric slab (12) are printed circuit boards (PCBs).

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