EP4588129A1

EP4588129A1 - An antenna system comprising a flat connector with impedance matching

Info

Publication number: EP4588129A1
Application number: EP23798973.6A
Authority: EP
Inventors: Kazuhiro Nakano; Arthur ROMEIJER
Original assignee: AGC Glass Europe SA
Current assignee: AGC Glass Europe SA
Priority date: 2022-12-02
Filing date: 2023-11-06
Publication date: 2025-07-23
Also published as: WO2024115047A1

Abstract

The present invention relates to an antenna system in a glazing comprising an antenna structure provided on at least a portion of the glazing, a connector having a main branch extends from the glazing, carries RF signals between the said antenna structure and an electronic device, the main branch is to be connected to the antenna structure from an antenna side and to the electronic device from an amplifier side.

Description

AN ANTENNA SYSTEM COMPRISING A FLAT CONNECTOR WITH IMPEDANCE MATCHING

FIELD OF THE INVENTION

[0001] The present invention relates to antenna system in a glazing comprising an antenna structure and a flat connector. More specifically the present invention relates to a wideband antenna laminated inside the glazing. Furthermore, specifically the present invention relates to an antenna operating in three different frequency ranges. Additionally, more specifically the present invention relates to a flat connector which is flexible that is able to adapt to the curvatures of a glazing, including a plastic or alike substrate. Even more specifically the present invention relates to a flat connector for carrying a RF signal to an antenna laminated in the glazing. The subject-matter of the invention relates to an antenna system comprising the connector, even more specifically a wide/multi band antenna laminated inside a glazing pane of a vehicle and even more specifically a wideband antenna made of thin metallic wires and operating in broadcasting bands (band II, III, IV and V). In addition, the present invention generally relates to connectors for vehicle antennas, even more specifically to flat connectors for use in connection with laminated glass antennas such as a wirelike antenna that is embedded inside a laminated window glazing.

BACKGROUND OF THE INVENTION

[0002] Nowadays there is a request from vehicle manufacturers to mount an increasing number of antennas in vehicles. Such antennas aim to render possible connected services (3G/4G/5G telecom, GNSS, RKE, V2X, Bluetooth, Wi-Fi) or to allow broadcasting services (AM, FM, DAB, TV). The trend is to deploy those antennas on window glasses of the vehicle. Furthermore, manufacturers require basic antenna designs that not disturbing the view of the driver and the aesthetics of the vehicle. It means the optimization of antenna design and placement in a vehicle is difficult even for one antenna. Especially designing a wide band antenna in an uncomplicated way is nearly impractical due to impedance matching concerns between the antenna structure and the electronic devices in the vehicle for wide operating frequency bands.

[0003] For efficient performance as an antenna system, the impedance of an antenna must be matched to the impedance of the transmission line that carries signals to and from the antenna. Any mismatch in impedance between antenna and the transmission line will increase the reflection of RF signal at the connection point between antenna and transmission line. Such impedance matching must occur physically at the point of interconnection between the antenna and the connector, and between the connector and the electronic device input. Preferably, the impedance should match in all operating frequency bands, and the impedance is often to be 50Q. That is one of the most important constraints for the antenna design, especially antennas on vehicle glazing, therefore a compromise of antenna performance is required. In addition to the antenna design, the connection to the electronic device, i.e. , the connector design has a significant role to realize a good impedance matching and to realize good performance as an antenna system.

[0004] With rapid growth in the demand for vehicle electronics, more and more antennas are being integrated to vehicles. Even though traditional mast or whip antennas have provided satisfactory performance in the past, often they are no longer preferred because they are considered to detract from vehicle aesthetics. Therefore, greater number of antennas or wideband antennas being integrated into window glazing, and there was a need in the prior art for an antenna connector to provide impedance matching to the laminated glass antenna. Such an antenna and the connector would be advantageous in comparison to a standard antenna connector.

[0005] International patent application WO2012136411 discloses a flat antenna connector with a conductive shield on top of the antenna trace to increase capacitive coupling to the ground to improve signal transmission and reduce interference. The coupling capacitance acts as a high pass filter that improves the TV antenna performance at the UHF band (470 MHz-860 MHz). However, that design tends to degrade antenna performance at the lower frequency band such as the TV VHF band from 47 to 240 MHz.

[0006] For example, United Stated patent application US2013069835 uses a balun coupled to a printed circuit board for providing impedance matching and utilizes two inductor and a capacitor to match impedance with more than one frequency band. However, such balun part increases the cost and manufacturing steps.

[0007] For example, United Stated patent application US20150222242 discloses a connector for a windshield antenna, comprising a base layer and an electrically conductive transmission line located on the base layer. The transmission line comprises four portions: a terminal portion, for connection to an electronic unit; a wide trace portion, a thin trace portion (having a width that is less than the wide trace portion) and a solder patch, for connection to an antenna in the windshield. The thin trace portion has a self-inductance which partly offsets a capacitive reactance of the antenna impedance in the UHF band. The wide trace portion is connected by capacitive coupling to ground, i.e. , vehicle body. The wide trace portion forms a shunt capacitor to ground, which contributes to matching the antenna impedance across VHF and UHF bands. However, such solution requires very thin width of metal tracing in a connector, and it tends to lead mechanical breakage of such metal tracing when manufacturing and delivering such cable and/or when installing such cables in a vehicle.

[0008] For example, European Patent No. EP3097603 discloses a feeding element coupled to an antenna element disposed on a substrate of a window, wherein the feeding element is disposed on an outer surface of a substrate. The feeding element may be spaced from and capacitively coupled to the antenna element. In a single port configuration, a single feeding element is coupled to a single antenna element. In a multi-port configuration, a single feeding element may be coupled to a plurality of antenna elements. The single feeding element may include separate conductors, each coupled to each separate antenna element. A feeding element may effectively operate as two separate feeding elements consolidated into a single feeding unit.

[0009] Although the problem of impedance matching between the antenna element and the transmission line seems to be solved in cited prior art, the optimization of the widths/lengths/thicknesses of the connector element requires precise craftmanship or machinery work. Generally, the manufacturing tolerances are off the chart from what is described in the prior art. Moreover, the connector solutions in the prior art relates to impedance matching for a specific frequency band. There is still a need for a connector itself with impedance matching for a wide band of frequencies with more freedom for tunability and for simple antenna designs.

SUMMARY OF THE INVENTION

[0010] The present invention provides an antenna system, especially a wide band antenna structure in a glazing including a flat connector and a vehicle including the glazing. The present invention also provides a flat connector for an antenna on a glazing or inside a glazing. The glazing includes a substrate formed from glass. The present invention also relates, in another aspect, to utilization of a such glazing in automotive or architecture industry for broadcasting purposes. The flat connector is operatively connected to and in electrical communication with the antenna for transferring/receiving radio signal to/from an electronic device.

[0011] The present invention also relates, in another aspect, a wide band antenna used with the flat connector, more specifically a wide band antenna operating in three different frequency bands, namely low frequency band, mid frequency band and high frequency band. Furthermore, the present invention provides the combination a flat connector and an antenna structure which realizes a good, realized antenna gain for the radio waves from VHF (band II and III) to UHF (band IV and V). Moreover, the present invention provides more freedom in design to tune the impedance matching and ease of manufacturability and installation.

[0012] The antenna of the present invention is preferably made of thin metallic wires, the antenna has at least two branches, one short and one long. The longer branch of the antenna is tuned for the low frequency band, and the shorter branch of the antenna is tuned for the mid frequency band. Two branches of the antenna overlap for at least an extent. By tuning the overlapping length and/or the distance between the two branches, additional resonances are created. Therefore, the overlapped region can be tuned for the high frequency band. The antenna of the present invention provides a good performance for the said three frequency bands with a clean and straightforward design.

[0013] The present invention also relates to the physical design of a flat connector, more specifically of a flat connector with impedance matching to an antenna structure, and even more specifically flat connectors utilized with wide band antennas. The present invention provides a flat connector which can help matching the impedance between the antenna structure and electronic devices in a vehicle, like an amplifier which results a considerable improvement of the overall realized antenna performance.

[0014] The flat connector of the present invention is suitable for a glazing comprising a substrate formed from glass and an antenna structure provided on at least a portion of the substrate, which is generally close to the edges of the substrate and the flat connector is to be attached or connected to the antenna structure to be in electrical communication, and the flat connector comprises a side branch of which one end is open, branching off between the two ends of the flat connector. In addition to all above, the present invention provides a flat connector with said properties in a cost-efficient manner.

[0015] The side branch of the flat connector is specifically designed to match the impedance between the antenna structure and the electronic device such as an amplifier. The flat connector utilizes the electrical connection between the electronic device and the antenna structure by a main branch (also called a signal line). The side branch is extended from the main branch and the other end of the side branch is open, i.e., not connected. The length of the side branch is tuned to improve impedance matching between the antenna structure and the electronic device.

[0016] The present invention further concerns a vehicle comprising such an assembly comprising the glazing, the antenna structure, the flat connector. Thanks to the solution proposed by the present invention, an antenna system operating in different wide frequency bands with a glazing can be realized with an uncomplicated design of an antenna in glazing and a flat connector to connect the antenna structure to an electronic device in a vehicle, provided good impedance matching between the antenna and the flat connector and between the flat connector and the electronic device in the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will now be described further, byway of examples, with reference to the accompanying drawings, wherein like reference numerals refer to like elements in the various figures. These examples are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples.

[0018] Fig.1 illustrates the top view of an antenna system, and Fig.2 illustrates the side view of a glazing.

Fig.3 illustrates a different embodiment of the antenna system in a glazing.

Fig.4 and Fig.5 illustrates the concept of the flat connector, while Fig.6 illustrates exploded cross section of the connector.

Fig.7 illustrates an embodiment of the antenna system in a glazing.

[0019] The elements illustrated in the figures are numbered as follows:

1 . Connector

11 . Base dielectric layer

12. Top dielectric tape

13. Dielectric layers

14. Conductor metal strip

15. Main branch

16. Antenna side

17. Amplifier side

18. Side branch

2. Glazing

21 . Inner glass

22. Outer glass

23. Interlayer

4. Antenna structure

41 . Feeding point

42. First branch

421 . First element

422. Second element

423. Third element

424. Fourth element

425. Fifth element

43. Second branch

431 . Sixth element

432. Seventh element

433. Eighth element

44. Overlapping region

V. Vehicle

E. Electronic device

A. Adhesive

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0020] The present invention will be described with respect to embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims.

[0021] While some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0022] As used herein, spatial or directional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.

[0023] Moreover, all ranges disclosed herein are to be understood to be inclusive of the beginning and ending range values and to encompass all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g., 1 to 6.1 , and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further, as used herein, the terms "deposited over" or "provided over" mean deposited or provided on but not necessarily in surface contact with. For example, a coating "deposited over" a substrate does not preclude the presence of one or more other coating films of the same or different composition located between the deposited coating and the substrate.

[0024] Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g., "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated. In this document, "configured to (or set to)" may be interchangeably used in hardware and software with, for example, "appropriate to", "having a capability to", "changed to", "made to", "capable of", or "designed to" according to a situation. In any situation, an expression "device configured to do" may mean that the device "can do" together with another device or component.

[0025] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), the constituent element may be directly connected to another constituent element or may be connected to another constituent element through another constituent element (e.g., a third constituent element).

[0026] In the following description, unless otherwise specified, expression “substantially” or “around” or “proximity” or “close to” preferably mean to within 10%, preferably to within 5% i.e. , in this context the terms should be understood as in the range of ± 10%, even more ± 5%. Tolerance may be selected depending on the nature of the intended applications.

[0027] “Connector” and “flat connector” and “electrical flat connector” are used interchangeably throughout the text, “pane” and “window pane” and “glass pane” and “glazing” and “laminated glazing” are used interchangeably throughout the text, “exterior vehicle electronics” and “exterior electronics” and “vehicle electronics” and “electrical device” and “electronic device” and “amplifier” are used interchangeably throughout the text, “overlapping region” and “overlapped region” are used interchangeably throughout the text, “antenna” and “antenna structure” are used interchangeably throughout the text.

[0028] Referring the figures, wherein like numerals indicate like or corresponding parts throughout the several views, a glazing (2) is generally shown per se, and it can be utilized on a vehicle (V) or on a building or alike. More preferably, the glass is further defined as an automotive glass but not limited to. In a preferred embodiment, the automotive glass is further defined as soda lime silica glass, which is well known for use in window glazing (2) of vehicles (V). However, it is to be appreciated that the glass may be any type of glass composition that is known in the art like the borosilicate, quartz, flat or float or etc.

[0029] The present invention proposes a wired connection to a glazing (2) preferably formed from glass for to be utilized in a vehicle (V), preferably on the laminated glazing (2) but not limited to. A vehicle (V) should be understood as any conveyor that transfers anything from point a to point b which includes any land, air or sea vehicles like car, van, lorry, motorbike, bus, tram, train, drone, airplane, helicopter and the like. An electronic device (E) should be understood as any electronic device (E) used in vehicles (V) which requires an antenna such as radio unit, amplifier etc. The term “electrical communication” should be understood that the elements mentioned are connected in such a way that electric current or RF signal can flow through.

[0030] A laminated glazing (2) refers to at least two sheets of glass, namely an inner glass (21 ) and an outer glass (22) being laminated with an interlayer (23). The sheets of glass (21 , 22) can be made of (mineral) glass, more specifically a silica-based glass, such as soda-lime-silica, alumino-silicate or boro-silicate type glass. The interlayer (23) is usually made of polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) but not limited to. The glazing (2) is placed onto the vehicle (V) with the help of an adhesive (A).

[0031] When the RF signals travel in a different medium like the glass panes (2), the wavelength in/inside the glazing (2) changes due to properties of the medium, especially the wavelength shortens because the speed of signals is slower in a medium having higher permittivity different than air/vacuum. The wavelength inside the medium and the wavelength in air can be compared by the wave shortening ratio. Wave shortening ratio (a) for the vehicle glass depends on the configuration of the glazing (2), and it is usually around in the range of 0.5 to 0.7. Thanks to the higher permittivity of glass, smaller/shorter antenna designs are possible.

[0032] An antenna system for a glazing (2) comprising an antenna structure (4) provided on at least a portion of the glazing (2), a connector (1 ) having a main branch (15) with two opposite ends (16, 17), that extends from the glazing (2), carries RF signals between the said antenna structure (4) and an electronic device (E), the main branch (15) is to be connected to the antenna structure (4) from an antenna side (16) and to the electronic device (E) from an amplifier side (17). The antenna system should be understood as the combination of the antenna structure (4) and the connector (1 ), which is suitable for to be used in/on a glazing (2).

[0033] An antenna structure (4) is applied across a region of the glazing (2) such that the antenna structure (4) is on at least a portion of the glazing (2), generally close to the edges of the glazing (2). The antenna structure (4) also comprises a feed point (41 ). Preferably, the antenna structure (4) is laminated inside the glazing (2) but not limited to. Preferably, the antenna (4) includes silver or copper, however, it is to be appreciated that other conductive metals may also be suitable for the antenna (4). The antenna (4) may be visible on the window pane (2) and typically comprises lines that extend horizontally across the window pane (2) but also it can be a transparent antenna (4) which can be made of typical transparent conductive coating for the automotive glazing. The antenna (4) can operate in a broad range of frequencies like 300kHz to 30 GHz or any other broad/narrow range in between thereof. The antenna (4) can serve to the electronic device (E) in the vehicle (V) like a radio tuner, TV tuner, amplifier or combination thereof. However, the antenna (4) may serve any function known in the art for such antennas (4).

[0034] Electronic device (E) such as the amplifier is grounded to the vehicle (V) body frame, meaning the vehicle (V) body frame act as a ground plane for the antenna structure (4) in the glazing (2). However, ground plane is not limited to the vehicle (V) body. In different embodiments, ground plane can be any suitable metallic layer in the vehicle (V) or in the glazing (2).

[0035] The present invention proposes a wire-like antenna (4), meaning an antenna (4) in the form of a wire, as commonly used in the automotive field. The wire-like antenna (4) is intended to be deposited near an edge of a glazing (2) and preferably laminated inside the glazing (2), i.e. , embedded on the interlayer (23). However, the present invention is not limited to wire-like antennas (4).

[0036] The antenna (4) of the present invention comprises at least two branches (42, 43) with open ends, the branches (42, 43) comprised of conductive wires, the first branch (42) is longer than the second branch (43) in length wherein the two branches (42, 43) overlap for at least an extent, namely for a minimum predefined length (L3) and having an overlapping region (44) to create additional resonance, i.e., at least two branches (42, 43), one first branch (42) and one second branch (43), made of electrically conductive wires, wherein other ends of the branches (42, 43) are open, i.e., not connected to. The branches (42, 43) extend preferably oppositely to each other from the feed point (41 ).

[0037] In different embodiments of the present invention, the first and second branches (42, 43) of the antenna (4) comprise at least one horizontal and one vertical part according to alignment on the glazing (2). In different embodiments, the first and second branches (42, 43) may have further horizontal and/or vertical parts as will be explained in a further embodiment down below, the number, the length and path of those branches define the frequency range in which the antenna (4) is functional. Therefore, the length and paths of those branches depend on the intended frequency range. Preferably, the first branch (42) is tuned for a low frequency band, and the second branch (43) is tuned for a mid-frequency band. In some embodiments, when a horizontal part of the branches (42, 43) meets with a vertical part of the respecting branch (42, 43), the connection may have a curvature. Both branches (42, 43) extend from the feeding point (41 ) and have specific design shapes depending on the frequency ranges to be tuned. The open end of the first branch (42) and the open end of the second branch (43) have the same orientation, i.e. , they are either horizontal or vertical or in any angle, together in the overlapping region (44). The free/open ends approach each other oppositely, i.e., from opposite directions and overlap at an extent. The open ends overlap, i.e., run along for at least a minimum predefined length (L3) to create additional resonances for the third frequency band, namely the high frequency band.

[0038] The lengths (Li, L2) of the branches (42, 43) and the length (L3) of the overlapping region (44) are tuned for three different frequency bands, namely low frequency band, mid frequency band and high frequency band. Longer branch (42) is tuned for low frequency band, shorter branch (43) is tuned for mid frequency band, and the overlapping distance (L3) of branches (42, 43) is tuned for high frequency band since overlapping region (44) is creating additional resonances in the high frequency band. Therefore, a wide band antenna (4) can be achieved. In different versions of this embodiment, the low frequency band is FM band (76-108 MHz), the mid frequency band is DAB band (170-240 MHz), and high frequency band is TV band (470-710 MHz).

[0039] Preferably, the length (Li , L2) of the branches (42, 43) is tuned to be resonated in at least one of the wavelength in the frequency bands. More preferably, the length (Li, L2) of the branches (42, 43) are equal to odd multiples of wave shortening ratio (a) times quarter of one of the wavelength in the frequency band, and more preferably the central or the average wavelength of the said frequency band, which can be formulated as follows; L = a * (2N - 1) * J where the A is one of the wavelength inside the desired frequency band, a is the wave shortening ratio ranging from 0.5 to 0.7, N is an integer larger than zero.

[0040] Preferably, the length (Li) of the first branch (42) is tuned to be resonated in at least one of the wavelength in the low frequency band. More preferably, the length (Li) of the branch (42) is equals to odd multiples of wave shortening ratio (a) times quarter of one of the wavelength in the low frequency band, preferably the central or the average wavelength of the said low frequency band, which can be formulated as follows;

L-L = a * (_2N₁ - 1) * — where Ai is one of the wavelength inside the low 4 frequency band, and Ni is an integer larger than zero. As described above in one specific embodiment, the first branch (42) is tuned for resonating in the FM band (76 - 108 MHz), where Ai is the one of the wavelength inside the FM band. The length (Li) can also be tuned for a different frequency band.

[0041] Preferably, the length (L2) of the second branch (43) is tuned to be resonated in at least one of the wavelength in the mid frequency band. More preferably, the length (L2) of the branch (43) is equals to odd multiples of wave shortening ratio (a) times quarter of one of the wavelength in the mid frequency band, preferably the central or the average wavelength of the said mid frequency band, which can be formulated as follows;

L₂ = a * (2/V₂ - 1) * — where A2 is one of the wavelength inside the mid 4 frequency band, and N2 is an integer larger than zero. As described above in one specific embodiment, the second branch (43) is tuned for resonating in the DAB band (170 - 240 MHz), where A2 is the one of the wavelength inside the DAB frequency band. The length (L2) can also be tuned for a different frequency band.

[0042] In a different embodiment, the distance (ds) between the two branches (42, 43) in the overlapping region (44) is less than or equal to 20mm. In another embodiment, in the overlapping region (44), the overlapping distance (L3) of antenna branches (42, 43) is more than 20mm, preferably more than 60mm, indubitably more than a minimum predefined length (L3), i.e., the two branches (42, 43) run along through the said distance which is greater than zero. The distance (ds) between the two branches (42, 43) and the distance (L3) of overlapping region (44) as mentioned are tuned to create additional resonances in the high frequency band. In a preferred embodiment, the length (L3) that the branches (42,43) run along together is more than the quarter of one of the wavelength in the intended frequency band, namely the minimum predefined length (L3) in this particular embodiment, i.e., the length (L3) can be formulated as follows;

L₃ > a * — where A3 is the one of the wavelength inside the desired frequency 4 band, namely the high frequency band, a is the wave shortening ratio ranging from 0.5 to 0.7.

[0043] In a different embodiment of the present invention, the length (Li) of the first branch (42) is tuned for FM band, specifically for 76 MHz - 108 MHz, and the length (L2) of the second branch (43) is tuned for DAB band, specifically for 170 MHz - 240 MHz. Two branches (42, 43) overlaps for at least an extent, i.e., the branches (42, 43) run along for at least a distance/length (L3) but not necessarily parallel, to create an overlapping region (44). By tuning the overlapping length (L3) or distance (ds) between the two branches (42, 43), the overlapped region (44) can create additional resonances for Band IV and band V, specifically for 470 MHz - 710 MHz. The design of the first branch (42) and the second branch (43) may be achieved in any combination that the branches (42, 43) tuned for the said frequency bands, a specific design for the branches (42, 43) is given in a specific embodiment below.

[0044] In different embodiments of the present invention, a wire-like antenna (4) can be formed by printing and baking paste containing conductive metal particles such as a silver paste, on an inner surface of a pane (2) of glass. However, the invention is not limited to this forming method as mentioned above, the antenna structure (4) can also be laminated inside the glazing (2). A linear element or a foil element made of a conductive material such as copper may be formed on an inner or outer surface of a pane (2) of glass or may be affixed to a pane of glass with an adhesive or may be provided between two or more panes of glass (laminated glazing). Additionally, a wirelike antenna (4) may be formed by forming a conductor layer given synthetic resin film in which a conductor layer of an antenna conductor is provided, of a synthetic resin film. Further, a wire-like antenna (4) may be formed by forming a flexible circuit board on which an antenna conductor is formed. [0045] In a different embodiment, the antenna (4) is formed on a surface of the glass sheet by sintering a silver paste containing a silver powder and a glass frit and which can also be deposited or painted or printed on the pane (2) surface or by any method as long as providing an antenna (4) on the surface of the glazing (2).

[0046] In another embodiment of the present invention, the antenna (4) may be screen printed or deposited by physical or chemical vapor deposition techniques or simply painted on the surface(s) of the glazing (2). The antenna (4) may comprise one or more of the following materials such as but not limited to C, Graphene, Ag, Au, Cu, Ni, Al, Ti, Cr, Fe, V or W.

[0047] In a specific embodiment of the present invention, the wire-like antenna (4) comprises at least a first branch (42), which acts as a radiator element. This first branch (42) is able to radiate and/or receive a radio signal at radio frequency in a first frequency band. The first branch (42) comprises a first element (421 ) extending from the feeding point (41 ) substantially parallel to the edge of the pane (2) where feeding point (41 ) located, a second element (422) following the first element (421 ) is at least partially substantially orthogonal to the first element (421 ), a third element (423) following the second element (422) is at least partially substantially orthogonal to the second element (422), optionally a fourth element (424) following the third element (423) is at least partially substantially orthogonal to the third element (423), and optionally a fifth element (425) following the fourth element (424) is at least partially substantially orthogonal to the fourth element(424). The elements (421 , 422, 423, 424, 425) may have a curvature while merging with each other. In one another specific embodiment, the fifth element (425) is substantially orthogonal to the first element (421 ). The first element (421 ), in some embodiments, almost extends to the corner of the edge of the pane (2). The third element (423), in some embodiments, extends across the pane (2) from one edge to other. In some embodiments, the first branch (42) looks almost like a loop or a O-shape or a rectangle-shape, i.e. , the open end of the fifth element (425) is provided close to the feeding point (41 ). It is to be understood that the first branch (42) comprises the first, second and third element (421 , 422, 423) and in a different embodiment comprises further the fourth element (424), and in another embodiment comprises further the fourth and fifth element (424, 425).

[0048] In a specific embodiment of the present invention, the wire-like antenna (4) further comprises at least a second branch (43), which acts as a radiator element. This second branch (43) is able to radiate and/or receive a radio signal at radio frequency in a second frequency band. The second branch (43) comprises a sixth element (431 ) extending from the feeding point (41 ) substantially parallel to the edge of the pane (2) where feeding point (41 ) located, optionally a seventh element (432) following the sixth element (431 ) is at least partially substantially orthogonal to the sixth element (431 ), optionally an eighth element (433) following the seventh element (432) is at least partially substantially orthogonal to the seventh element (432). The elements (431 , 432, 433) may have a curvature while merging with each other. In one another specific embodiment, the eighth element (433) is substantially parallel to the sixth element (431 ). The sixth element (431 ), in some embodiments, almost extends to the corner of the pane (2). The eighth element (433), in some embodiments, extends across the pane (2) from one edge to other. In some embodiments, the second branch (43) looks almost like a U-shape or a J-shape, i.e. , the open end of the eighth element (433) is almost in line with the feeding point (41 ) by the line crossing the feeding point (41 ) and perpendicular to the edge of the pane (2) where feeding point (41 ) provided. It is to be understood that the second branch (43) comprises the sixth element (431 ) and in a different embodiment comprises further the seventh element (432), and in another embodiment comprises further the seventh and eighth element (432, 433).

[0049] As described above, the first element (421 ) and the sixth element (431 ) of the antenna (4) extends from the feeding point (41 ) to opposite directions each other. In one embodiment, the feeding point (41 ) is in the middle of the edge of the pane (2) and the length of the first and sixth elements (421 , 431 ) are almost identical to each other.

[0050] The overlapping region (44) is to be understood that the elements (421 , 422, 423, 424, 425, 431 , 432, 433) of two branches (42, 43) overlap at an extent, i.e., there may be many combinations to achieve such an overlapping region (44). Namely, in one embodiment, the first branch (42) comprises the first, second and third elements (421 , 422, 423) and the second branch (43) comprises the sixth, seventh, eighth elements (431 , 432, 433). In another embodiment, the first branch (42) comprises first, second, third and fourth elements (421 , 422, 423, 424) and the second branch (43) comprises the sixth and seventh elements (431 , 432) or sixth, seventh and eighth elements (431 , 432, 433). In another embodiment, the first branch (42) comprises the first, second, third, fourth and fifth elements (421 , 422, 423, 424, 425) and the second branch (43) comprises the sixth element (431 ) or sixth and seventh elements (431 , 432) or sixth, seventh and eighth elements (431 , 432, 433). The number of elements each branch (42, 43) has depends on the frequency bands desired to be tuned in.

[0051] Preferably, the first branch (42) and the second branch (43) overlaps with each other at the region where sixth element (431 ) meets with fifth element (425) and even more seventh element (432) meets with fourth element (424), further even more eight element (433) meets with third element (423), thereby creating an overlapping region (44). It should be understood that overlapping region (44) can be designed in various arrangements as mentioned above that allows tunability for the desired frequency bands. In one specific embodiment, ends of both branches (42, 43), i.e. , the elements (423, 424, 425, 431 , 432, 433) mentioned above, overlap each other by extending parallelly close to each other.

[0052] In the overlapping region (44), the overlapping distance of antenna branches (42, 43) is more than the predefined minimum length (L3) as described above and more than 20mm, preferably more than 60mm, i.e. the total length of fifth, fourth and third elements (423, 424, 425) in the overlapping region (44) is more than 20mm, preferably more than 60mm or in other words, the total length of sixth, seventh, eighth elements (431 , 432, 433) in the overlapping region (44) is more than 20mm, preferably more than 60mm. In a preferred embodiment, those elements (423, 424, 425, 431 , 432, 433) extend parallelly close to each other in the overlapping region (44) for the aforementioned length (L3).

[0053] The distance (ds) between the two branches (42, 43) in the overlapping region (44) is less than or equal to 20mm. By tuning the length of the elements (423, 424, 425, 431 , 432, 433) in the overlapping region (44) and the distance (ds) between two branches (42, 43) in the overlapping region (44), additional multiple resonances are created. The overlapping region (44) can be tuned for resonating in a third frequency band, namely the high frequency band.

[0054] A flat connector (1 ) proposed by the present invention is used for providing the electrical connection between the antenna (4) and the electronic device (E), more specifically flat connector (1 ) transmits RF signals in between the antenna (4) and the electronic device (E). In general, flat connector (1 ) has a socket at one of its ends (17), which is connected to the electronic device (E). The other end (16) of the flat connector (1 ) is soldered to the antenna (4), however this is not a requirement and the electrical communication can be achieved in any other methods.

[0055] Referring to figures, a flat connector (1 ) is operatively connected to and in electrical communication with the antenna (4). The radio signal is transferred/carried over a main branch (15) of the flat connector (1 ) which acts as a transmission line. One end of the main branch (15), so called the amplifier side (17) is connected to the electronic device (E) like the amplifier, the other end of the main branch (15), so called the antenna side (16) is connected to the antenna (4). The connection to the antenna (4) can be realized by a solid connection like the soldering or gluing conductively or by a capacitive coupling or by any other method to realize the electrical communication between the main branch (15) and the antenna (4). The flat connector (1 ) is aimed to transfer/receive radio signal between the electronic device (E) and the antenna (4) provided on the glazing (2).

[0056] The flat connector (1 ) of the present invention further comprises a side branch (18) extending between the two ends of the main branch (15) and having an open end, length of which (d1 ) is tuned to improve impedance matching between the antenna structure (4) and the electronic device (E), i.e., wherein the flat connector (1 ) has a side branch (18) with an open end for impedance matching, the side branch (18) extending between the two ends of the flat connector (1 ), i.e., between the amplifier side (17) and the antenna side (16).

[0057] It has been found that impedance matching occurs when the length (di) of the side branch (18) is in the range from one sixth to one third of one of the wavelength in the frequency band (A3/6 < d1 < As/3), and more specifically around the quarter of one of the wavelength in the frequency band to be received by the antenna (4) which needs the impedance matching. In the preferred embodiment of the present invention, the A3 is one of the wavelength in the high frequency band and might be the same or different than the wavelength used in calculation of the overlapping distance (L3). For example, tuning the length (di) of the side branch (18) around 135 mm allows impedance matching occurs in the 470 MHz - 710 MHz band range. Adapting the length (di) of the side branch (18) allows tunability freedom for the impedance matching and also eliminates the requirement for modifying the length or thickness of the main branch (15) itself which may cause installation problems and even manufacturing problems. Furthermore with such accommodation, total length (de) of the flat connector (1 ) can be kept in the range of 50 mm to 250 mm, even less than 200 mm.

[0058] In another embodiment of the present invention, the width (d2) of the side branch (18) is in the range of 1 mm to 20 mm, preferably 1 mm to 10 mm, more preferably 1 mm to 5 mm, even more preferably 1 mm to 3 mm. It has been found that the tolerance of the width (d2) of the side branch (18) is not influential as the tolerance of the length (di) of the side branch (18) for impedance matching tuning. Aforementioned allows flexibility for the manufacturing of the flat connector (1 ) and stability against manufacturing tolerances and presents a variety of preferences for the intended application.

[0059] In another embodiment of the present invention, the side branch (18) extends from the proximity of the amplifier side (17). The proximity of the amplifier side (17) should be understood as branching off location of the side branch (18) is closer to the amplifier side (17) than the antenna side (16). In a version of this embodiment, the distance (ds) between the amplifier side (17) and the side branch (18) is less than 30 mm, preferably less than 20 mm, more preferably less than 10 mm, even more preferably less than 5 mm, i.e. , the distance (ds) between the amplifier side (17) and the connected end of the side branch (18) is less than 30 mm, preferably less than 20 mm, more preferably less than 10 mm, even more preferably less than 5 mm. Therefore, the side branch (18) may branch off from the main branch (15) at the amplifier side (17), allowing an uncomplicated assembling/fabrication.

[0060] In another embodiment of the present invention, the side branch (18) runs along with the main branch (15), in other words, the side branch (18) extends along with the main branch (15). In a version of this embodiment, the side branch (18) goes parallel with the main branch (15) and the open end of the side branch (18) remains outside the glazing (2). Depending on the requirement for the impedance matching frequency range, the length (di) of the side branch (18) changes and the open end of the side branch (18) may remain inside the laminated glazing (2).

[0061] In another embodiment of the present invention, the distance (d4) between the main branch (15) and the side branch (18) is in the range of 0.1 mm to 10 mm, preferably 0.1 mm to 5 mm, more preferably 0.1 mm to 3 mm. It has been found out that the tolerance of the distance (d4) between the main branch (15) and the side branch (18) is not much influential to the impedance matching as the tolerance of the length (di) of the side branch (18). Yet another flexibility for the ease and simple manufacturing of the flat connector (1 ).

[0062] In various embodiments of the present invention, the flat connector (1 ) comprises a base dielectric layer (11 ) and a top dielectric tape (12) and a conductor metal strip (14) in between and optional dielectric layers (13) in between. The conductor metal strip (14) that is printed on a dielectric layer (11 , 13) and covered with a dielectric layer/tape (12, 13), and represents the main branch (15) and the side branch (18) for the transmission of the signal, i.e., forming a main branch (15) for transmitting a signal and a side branch (18) to improve the efficiency of such signal transmission. One end of the flat connector (1 ) is soldered/glued/coupled capacitively to an antenna (4) and remains in the glazing structure (2) when the window is laminated glazing, this end of the flat connector (1 ) will be referred to “antenna side” (16). The other end of the connector (1 ) wraps over the outside edge of the glazing (2) to connect to the electronic device (E) in a vehicle (V), this end of the flat connector (1 ) will be referred to “amplifier side” (17). The side branch (18) also comprises a conductor metal strip (14) inside along its length. However, the flat connector (1 ) can be achieved in any manner satisfying the features described above.

[0063] In another embodiment of the invention, the base dielectric layer (11 ), the top dielectric tape (12) and/or the optional dielectric layers (13) contains a plastic, preferably polyimide (PI), polyamide (PA), polyethylene (PE), polypropene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutadiene, polyvinyl chloride (PVC) or polytetrafluoroethene (PTFE), and mixtures and/or copolymers thereof, but not limited to. The base dielectric layer (11 ), the top dielectric tape (12) and/or the optional dielectric layers (13) can also be a lacquer layer, preferably alkyd resin, acrylic resin, epoxy resin or polyurethane, or an adhesive, preferably acrylate adhesive, methyl methacrylate adhesive, Polyuerthane, polyolefins, Cyanoacrylate adhesive, polyepoxides, silicone adhesive and I or silane-crosslinking polymer adhesive, RTV silicone rubber, HTV silicone rubber, peroxide-crosslinked silicone rubber and/or addition-crosslinked silicone rubber, and mixtures and/or copolymers thereof, but not limited to.

[0064] The present wire-like antenna (4) comprises the feeding point (41 ). The feeding point (41 ) allows for electricity/signal furnishing of the antenna (4). The flat connector (1 ) is designed to be connected to the feeding point (41 ). The feeding point (41 ) is preferably located in the close proximity of one of the edges of the pane (2). The first and second branch (42, 43) extend oppositely from the feed point (41 ).

[0065] In one embodiment, the flat connector (1 ) acts as a simple electrical connection in the lower frequencies like the FM or DAB band range, and acts as a RF transmission line in the higher frequencies like the TV bands, causing impedance mismatches in higher frequencies. Consequently, the side branch (18) allows better impedance matching between the antenna (4) and the electronic device (E) in higher frequency ranges, i.e., the side branch (18) improves the matching between higher impedance antenna (4) and lower impedance electronic device (E) like amplifier which is often 50Q. On the other hand, such side branch (18) doesn’t affect to the impedance matching in lower frequency bands like FM or DAB since the length of the side branch (18) and the main branch (15) are both much shorter than the wavelength of lower frequency bands. Therefore, the aforementioned grants possibility of designing wideband antennas (4). The inventors found that, such benefit of this invention is maximized in case the length (de) of the main branch (15) is in the range < d₆ <

8

— , where A2 is one of the wavelength inside the mid frequency band and A2 can be 8 same or different than the wavelength used in calculation of length (L2) of second branch (43), A3 is one of the wavelength inside the high frequency band and same or different than the A3 used in any other calculations.

[0066] The said antenna (4) structure is designed in a simple way to receive wideband radio waves from FM band to TV band by just one antenna (4). The impedance of the antenna (4) is around 50Q in the lower frequency band and is much higher than 50Q in the higher frequency band. The antenna (4) as it is, has already higher gain in the lower frequency bands, and thanks to the flat connector (1 ) described above, the antenna (4) has higher gain in the higher frequencies when connected by the flat connector (1 ) thanks to better impedance matching characteristics for the higher frequency band, i.e., the side branch (18) in the flat connector (1 ) decreases the mismatch losses in the higher frequency band.

[0067] Impedance matching effect in the higher frequency band is realized by tuning the length (di) of the side branch (18) of the flat connector (1 ), mainly providing it to be preferably around quarter of the central wavelength of the desired frequency range as described above.

[0068] The present invention also proposes an antenna system in a glazing (2) comprising a substrate formed from glass and an antenna (4) described above in detail provided on at least a portion of the glazing (2) and a flat connector (1 ) described above in detail is attached to the antenna (4) so as to be in electrical communication with the antenna (4). The antenna (4) is equipped with at least two conductive wires, namely the first and second branch (42, 43). The conductive wires are placed vertically, but they can also be placed horizontally or along any other orientation over the glazing (2).

[0069] The present invention also proposes the usage of such an antenna system in a glazing (2) described above in detail for automotive or architecture or telecommunication applications. Applications of such an antenna system in a glazing (2) is not limited to just automotive industry, the antenna system in a glazing (2) can be used for internal and external windows of buildings. For example, the antenna (4) can be a 5G or a Wi-Fi antenna on the windows of a building and the flat connector (1 ) is used for both signal transmission and helping impedance matching.

[0070] In different versions of this embodiment, the glazing (2) is a vehicle glazing used in vehicle’s windshield, sidelites, backlite, or roof. In another embodiment, the glazing (2) is a glazing used in facades of a building facilitating a wide band antenna (4) for the building thanks to the flat connector (1 ).

[0071] The present invention also proposes a vehicle (V) comprising at least one glazing (2) as described previously. In a preferred embodiment, the glazing (2) is a windshield or a sidelite or a backlite or a roof or a rearlite of a vehicle or any surface where glass is utilized. The present invention also proposes a vehicle comprising at least one assembly as described previously.

[0072] The present invention also proposes the usage of a flat connector (1 ) as described above in detail as a signal carrier to an antenna (4) provided on glass substrate for panes (2). As described above in detail that usage of a such flat connector (1 ) on glass surfaces provides better realized antenna performance by improving impedance matching between an antenna (4) and an electronic device (E). The flat connector (1 ) of the present invention can be tuned by adjusting the length (di) of the side branch (18) for impedance matching to any antenna design. Therefore the connector (1 ) is not limited for to be used with the antenna (4) described above.

[0073] With the connector (1 ) of the present invention, antennas (4) working in a wide range of frequency bands with a simple design is achievable with a simple physical design, and without concerning the impedance matching issue. The flat connector (1 ) of the present invention provides better antenna performance in a wide range of frequency bands, that makes compatibility for a wide range of applications on glass surfaces with lower cost and less difficulty of installation.

[0074] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments.

Claims

1 . An antenna system for a glazing (2) comprising

- an antenna structure (4) provided on at least a portion of the glazing (2),

- a connector (1 ) having a main branch (15) with two opposite ends (16, 17), that extends from the glazing (2), and carries RF signals between the said antenna structure (4) and an electronic device (E), the main branch (15) is to be connected to the antenna structure (4) from an antenna side (16) and to the electronic device (E) from an amplifier side (17) characterized in that the connector (1 ) further comprises a side branch (18) extending between the two ends of the main branch (15) and having an open end, length of which (di) is tuned to improve impedance matching between the antenna structure (4) and the electronic device (E).

2. An antenna system according to claim 1 , wherein the length (di) of the side branch (18) satisfies A3/6 < di < A3/3, more specifically satisfies di ~ A3/4, wherein A3 is the one of the wavelength in a high frequency band of which impedance matching occurs.

3. An antenna system according to claims 1 or 2, wherein the length (di) of the side branch (18) satisfies 50 mm < di < 200 mm.

4. An antenna system according to according to any of the previous claims, wherein the width (d2) of the side branch (18) satisfies 1 mm < di < 20 mm.

5. An antenna system according to any of the previous claims, wherein the side branch (18) extends from the proximity of the amplifier side (17) of the main branch (15), closer than the antenna side (16).

6. An antenna system according to any of the previous claims, wherein the side branch (18) extends along the main branch (15).

7. An antenna system according to any of the previous claims, wherein the distance (d4) between the side branch (18) and the main branch (15) satisfies 0.1 mm < d4 < 10 mm. An antenna system according to any of the previous claims, wherein the length (de) of the main branch (15) satisfies A3/8 < de < A2/8, wherein A3 is the one of the wavelength in a high frequency band of which impedance matching occurs and A2 is the one of the wavelength in a mid-frequency band. An antenna system according to any of the previous claims, wherein the antenna structure (4) having at least two branches (42, 43) with open ends, a first branch (42) is longer than a second branch (43) in length wherein the two branches (42, 43) overlaps for at least an extent and having an overlapping region (44) to create additional resonance. An antenna system according to claim 9, wherein the length (Li, L2) of the branches (42, 43) and the length (L3) of the overlapping region (44) are tuned for three different frequency bands, namely low frequency band, mid frequency band and high frequency band. An antenna system according to claims 9 or 10, wherein the length (Li , L2) of the branches (42,43) of the antenna (4) is formulated as wherein the A is the one of the wavelength inside the intended frequency band respectively, a is the wave shortening ratio ranging from 0.5 to 0.7, N is an integer larger than zero. An antenna system according to claims 9 to 11 , wherein the length (L3) of the overlapping region (44) is formulated as wherein A3 is the one of the wavelength inside the high frequency band, a is the wave shortening ratio ranging from 0.5 to 0.7. An antenna system according to claims 9 to 12, wherein the length (L3) of the overlapping region (44) is more than 20mm, preferably more than 60mm. An antenna system according to claims 9 to 13, wherein the distance (ds) between the antenna branches (42, 43) in the overlapping region (44) is less than or equal to 20mm. A vehicle comprising at least one glazing (2) having an antenna system according to claims 1 to 14, wherein the connector (1 ) is a flat connector and laminated inside the glazing (2) and wherein, the said antenna structure (4) is composed of thin metallic wires.