WO2009074537A1

WO2009074537A1 - Antenna

Info

Publication number: WO2009074537A1
Application number: PCT/EP2008/067023
Authority: WO
Inventors: Peter Paulus
Original assignee: Pilkington Automotive Deutschland Gmbh
Priority date: 2007-12-11
Filing date: 2008-12-08
Publication date: 2009-06-18
Also published as: EP2223383A1; JP2011507373A; GB0724157D0

Abstract

An antenna assembly (3) for a vehicle is disclosed. The antenna assembly- comprises a vehicle roof glazing (5) comprising a sheet of glazing material. There is an electroconductive element (9) facing the vehicle roof glazing. An antenna connection point (11) is arranged to be in electrical communication with the electroconductive element. The electroconductive element is arranged to be in electrical communication with a radio receiver via the antenna connection point. The electroconductive element is configured to function as an antenna for the reception of radio signals without an intervening amplifier in electrical connection between the antenna connection point and the radio receiver.

Description

ANTENNA

The present invention relates to an antenna assembly for a vehicle, particularly to an antenna assembly for incorporating into an aperture in the roof of a vehicle.

It is common practice in the motor industry to use a vehicle windscreen or backlight as a carrier for an antenna. When the backlight is used, compromises must be made in order to provide the heater/demister function in addition to the antenna function. Performance of windscreen antennae is better but suffers from the problem of electronic noise generated in the dashboard and engine compartment. Windscreen and backlight antennae normally have an amplifier to compensate for weak signal reception and/or cable losses. The need for an amplifier increases complexity and costs.

Use of a vehicle roof glazing, such as an optically transparent rooflight, as a carrier for the antenna has difficulties. Normally the rooflight comprises a moveable glazing, as in a sunroof, and as such the antenna may be hidden underneath the metal roof portion of the vehicle bodywork when the sunroof is slid into an open position. This is not practical because signal reception would be compromised when the sunroof is open.

There are however certain situations where a moveable vehicle rooflight, such as a sunroof, is not required and a fixed vehicle rooflight is desirable. A fixed vehicle rooflight does not have the same complexity as a moveable vehicle rooflight because there are no moving parts associated therewith. A fixed vehicle rooflight may be fixed into an appropriately sized aperture in the vehicle bodywork and can provide an occupant of the vehicle with improved interior lighting and a panoramic view. In contrast to a moveable rooflight, a fixed rooflight may contribute to the structural rigidity of the vehicle bodywork.

DE102005035427A1 describes a roof module for a vehicle and in particular the integration of an antenna in the roof module. The problem with this type of roof antenna is that an amplifier is needed for the antenna to function adequately for the reception of radio signals, thereby increasing costs and complexity.

DE 19637794 describes a vehicle roofiight having an integrated antenna. The roofiight is moveable between an open and a closed position. In order to maintain the effectiveness of the antenna, the antenna is placed near the front of the moveable glazing. The problem with this type of roofiight is that because the roofiight is moveable, the antenna must be positioned such that signal reception is not compromised when the roofiight is open. This places restrictions on the size of the antenna that can be incorporated in the roofiight and therefore compromises signal reception performance.

The present invention aims at least partially to overcome the problems of known antenna assemblies for incorporating into an aperture in the roof of a vehicle, and aims to provide an improved antenna assembly for incorporating into an aperture in the roof of a vehicle.

Accordingly the present invention provides an antenna assembly for a vehicle comprising a vehicle roof glazing comprising a sheet of glazing material, an electroconductive element facing the vehicle roof glazing, and an antenna connection point arranged to be in electrical communication with the electroconductive element, the electroconductive element arranged to be in electrical communication with a radio receiver via the antenna connection point, wherein the electroconductive element is configured to function as an antenna for the reception of radio signals without an intervening amplifier in electrical connection between the antenna connection point and the radio receiver. Such an antenna assembly has the advantage of being simpler to assemble, requiring less components and is easier and less expensive to manufacture.

Preferably the vehicle roof glazing further comprises a layer of laminate material disposed on one side of the sheet of glazing material. A suitable laminate material is polyvinyl butyral (PVB). Incorporating a layer of laminate material has the advantage that the vehicle roof glazing has an improved intruder resistance. Also, by selecting a tinted laminate material the transmitted and/or reflected colour of the rooflight portion may be chosen by a choosing a suitably tinted interlayer. Suitably the electroconductive element is disposed between the layer of laminate material and the sheet of glazing material. This has the benefit that the electroconductive element is protected from being touched, so is less likely to be damaged. Preferably the electroconductive element is supported by the layer of laminate material. This has the advantage that the vehicle rooflight may be retrofit with the layer of laminate material, thereby providing an improved antenna assembly according to the present invention. The vehicle roof glazing may be a laminated glazing, comprising two sheets of glazing material and a layer of laminate material disposed therebetween.

Preferably the electroconductive element is bonded to the sheet of glazing material. By "bonded" it is meant any technique for attaching the electroconductive element to the sheet of glazing material such that the electroconductive element may not be easily removed therefrom. The electroconductive element may be directly bonded to the sheet of glazing material, or may be indirectly bonded to the sheet of glazing material. For example, if the electroconductive element is a copper wire clad inside a plastic sheath, the electroconductive element may be bonded to the sheet of glazing material by using an adhesive to glue the sheath thereto. A benefit of bonding the electroconductive element to the sheet of glazing material is that the antenna assembly may be provided with an optimised performance prior to installation in a vehicle roof, and since the antenna is not able to be removed from the first sheet because it is bonded thereto, antenna performance is not able to be compromised by tampering with the electroconductive element.

Preferably the electroconductive element comprises a metallic coating. Suitably the metallic coating is optically transparent, which has the advantage that an antenna can be constructed that is not visible to an occupant of the vehicle and thereby does not interfere with the occupants view. Preferably, the electroconductive element comprises an electrically conductive ink. The ink may be deposited using conventional techniques such as screen printing or ink jet printing.

Preferably the electroconductive element comprises a metallic member such as a bar or a wire. A metallic bar has the advantage that it may be used to attach other vehicle accessories thereto, for example a blind assembly for a sunshade for the aperture. A wire has the benefit that it can be easily assembled into a suitable shape for the antenna, for example by bending. The wire may be embedded in a layer of laminate material.

To improve signal reception, preferably the antenna assembly has an electroconductive element that extends between opposite edges of the vehicle roof glazing. Preferably the electroconductive element is configured to extend along a centre axis of the vehicle rooflight glazing. A vehicle roofiight glazing normally has a substantially rectangular shape in outline and the centre axis may be the longitudinal or transverse axis thereof. By having the electroconductive element extending along a centre axis of the vehicle roof glazing, the distance of the electroconductive element to the vehicle bodywork may be maximised, thereby improving antenna performance. This is because unwanted capacitance to the vehicle body is reduced, since there is no sheet metal near to the electroconductive element.

A preferred arrangement for the electroconductive element is that it is configured to function as a slot antenna when the antenna assembly is installed in a vehicle roof. When installed in this way, the combination of vehicle body and electroconductive element is able to function as a slot antenna.

If the vehicle roof glazing has a major surface that is a sufficiently large area, the electroconductive element may be configured as a quarter wave element for the reception of FM signals. The length of the electroconductive element may be adjusted to optimise signal reception. The length of the electroconductive element is defined as the greatest distance from the antenna connection point to the end of electroconductive element. Preferably the length of the electroconductive element is between 50cm and 100cm.

Preferably the antenna is configured to receive radio waves in at least one of the AM (153 to 1610 kHz), FM (87.5 to 108.0 MHz), SW (2.3 to 26.1MHz) or LW (153kHz to 279 kHz) frequency ranges.

Preferably the antenna connection point is located in the vicinity of the periphery of the vehicle roof glazing.

Preferably the antenna connection point is attached to the vehicle roof glazing.

Suitably the sheet of glazing material comprises a sheet of plastic material or a sheet of vitreous material. Preferably the sheet of glazing material is a sheet of glass. Preferably the sheet of glass has been produced by a float process. Preferably the sheet of glass has been toughened by a thermal or chemical process.

The vehicle roof glazing may be optically opaque, but the vehicle roof glazing must not prevent the electroconductive element from functioning as an antenna.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure l is a perspective representation of a motor vehicle incorporating an antenna assembly according to the present invention;

Figure 2 is a plan view of an embodiment of the present invention;

Figure 3a is a plan view of an embodiment of the present invention; Figure 3b is a cross sectional view of the embodiment shown in figure 3a; Figures 4a and 4b are embodiments of the present invention wherein the electroconductive element is configured to function as a slot antenna when the roofiight is installed in a vehicle roof; Figures 5 to 10 are plan views of different embodiments of the present invention;

Figures 11 to 15 are cross sectional views of different embodiments of the present invention.

Throughout the following description, the terms "inner" and "outer" will be used. When referring to the inner surface of a vehicle roofiight, it is meant the surface of the roofiight that faces the interior of the vehicle when the roofiight is installed in a vehicle. The outer surface is the surface of the roofiight that is on the exterior of the vehicle when the roofiight is installed in the vehicle.

The embodiments of the present invention herein described provide an antenna assembly for a vehicle roof comprising an electroconductive element configured to function as an antenna without needing an amplifier. When the antenna assembly is coupled to a suitable receiving device, signal reception is sufficiently strong such that the receiving device is able to adequately process information transmitted by the signal, without the need for signal amplification, for subsequent presentation of the information to an occupant of the vehicle. For example, when the receiving device is a radio receiver, signal reception is strong enough that an occupant of the vehicle is able to listen to a radio broadcast.

Figure 1 shows a perspective view of a car 1 incorporating an antenna assembly 3 according to the present invention. The antenna assembly comprises a fixed vehicle roofiight glazing 5 that has a sheet of glazing material 7 that is a single sheet of toughened float glass. An electroconductive element in the form of a silver ink line 9 is bonded to the inner surface of the glass sheet 7. The silver ink line 9 has been conventionally printed on the surface of the glass sheet, for example by screen printing or ink jet printing, and subsequently heat or UV cured. The silver ink line is in electrical communication with antenna connection point 11 that is located near the front edge of the roofiight. The front edge of the roofiight is the edge nearest to the vehicle windscreen. It is preferable to locate the antenna connection point near the front edge of the vehicle rooflight glazing because this minimises the length of cable required to bring the antenna into electrical communication with a receiving device. Suitable receiving devices are normally located in the dashboard area of the vehicle. The centre conductor of a conventional coaxial cable is used to electrically connect the antenna connection point to the receiving device. The outer conductor of the coaxial cable should be grounded, normally to the car body. By having the antenna connection point near the front edge of the rooflight glazing, a short length of cable can be used. This increases performance and reduces costs.

The silver ink line 9 extends along the longitudinal centre axis of the rooflight glazing 5. The sheet of glass 7 may be replaced by a sheet of plastic. The rooflight glazing 5 may be tinted or may be optically opaque. The fixed vehicle rooflight glazing 5 is fixed to the car body 13 and is not moveable with respect thereto. The fixed vehicle rooflight glazing contributes to the rigidity of the car body.

The AM (and also LW/SW) signal reception of this antenna assembly is acceptable because the silver ink line 9 is about 100cm in length. The silver ink line has low capacitance to the car body, when compared with conventional windscreen and backlight antennae. When compared with a conventional rod antenna, the unwanted capacitance of the silver ink line to the vehicle bodywork is reduced because there is no metal sheet near to the silver ink line. When compared to an antenna in a conventional integrated windscreen/backlight antenna, the capacitance of the antenna in the above antenna assembly is lower because there is no need for the antenna to be located near an edge of the glazing (and therefore near to the metal vehicle bodywork) so as not to obstruct the view of the driver.

For the reception of FM signals, the antenna assembly benefits from the electroconductive element being horizontally disposed when installed in a vehicle. This is advantageous because in many parts of the world, for example Europe and Japan, most FM transmitters for radio broadcasts transmit a horizontally polarised signal. It is well known that the length of an antenna may be varied to improve signal reception of AM and FM radio signals. To improve AM reception, the electrically conductive portion should be made as long as is practical. To improve FM reception, the length / of the antenna for the optimum reception of a signal of a particular wavelength λ is given by the following expression: λxSF_

^~ 4^~ where SF is a shortening factor that takes into account the dielectric medium immediately surrounding the antenna. For air, SF=I, whereas for a single sheet of toughened glass, SF is between 0.7 and 0.85.

Figure 2 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 20 comprising a sheet of glazing material 7 that is a single sheet of toughened float glass. An electrically conductive wire 24 of length between about 0.6 and Im is fixed to a major face of the glass sheet. The wire may be enclosed in a plastic sheath. When fitted in a vehicle, it is preferred to have the wire on the inner surface, but the wire may be on the outer surface. It is preferable to have the wire on the inner surface to avoid potential corrosion of the wire, if located on the outer surface. In addition, the connection to the cable to the radio receiver can be arranged more easily and effectively. The wire 24 extends along the longitudinal centre axis of the glass sheet. An antenna connection point 11 is located near the front edge of the rooflight and is in electrical communication with the wire. When the wire is coupled to a suitable receiving device via the antenna connection point, the wire can function as an antenna without needing an intervening amplifier. The vehicle rooflight glazing 20 may have a peripheral seal (not shown) around the edges thereof to ensure a water tight seal when installed and fixed in the roof of a vehicle. Using a wire has the advantage that it can be easily configured into a suitable shape for an antenna.

Figure 3a shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 30 having a sheet of glazing material 7 that is a single sheet of toughened float glass. Bonded to the inner surface of the roofiight is an electroconductive element 34 that is a conventional electrically conductive silver ink that has been screen printed and suitably heat cured. The electroconductive element functions as an antenna with needing an intervening amplifier. The silver ink is in electrical communication with antenna connection point 11 and the silver ink line functions as an antenna without the need for an intervening amplifier in between the antenna connection point and a radio receiver. Use of an electrically conductive ink has the advantage that the ink can be deposited on the surface of the glass sheet using conventional deposition techniques, such as screen printing or ink jet printing. Figure 3b is a cross section through the line A-A' of the antenna assembly shown in figure 3a.

Figure 4a shows a plan view of an antenna assembly comprising a vehicle roofiight glazing 40 having a sheet of glazing material 7 that is a sheet of toughened float glass. An electrically conductive coating 44 is bonded to the inner surface of the glass sheet. The coating is configured to form a slot antenna when the roofiight glazing is installed in a vehicle roof, the slot being between the coating and the vehicle bodywork. The coating may be deposited when the glass is produced using an online atmospheric chemical vapour deposition technique or the coating may be deposited by a subsequent offline process. The coating may be optically transparent. The region 46 void of coating may be produced by removing the coating by any suitable technique such as acid etching or laser ablation. The region 46 may also be masked during the coating process. The region 46 void of coating may be all around the edge of the glazing as shown in figure 4b. The antenna assembly shown in figure 4b comprises a vehicle roofiight glazing 41 having a sheet of glazing material 7 that is a sheet of toughened float glass. An electrically conductive coating 45 is bonded to the inner surface of the glass sheet. The embodiment shown in figure 4b provides better LW, AM and SW reception than the embodiment shown in figure 4a. If only FM is required, the length of the region 46 may be configured to have a length of a halve wavelength of the radio wave to be received (corrected by the shortening factor). There is an antenna connection point 11 to couple the antenna to a suitable receiving device. When this antenna assembly is installed in a vehicle, the antenna connection point 11 normally will be connected to the inner conductor of a coaxial cable, and the outer conductor of the coaxial cable will be in electrical communication with the surrounding metal bodywork. When coupled in this way, the metal coating functions as a slot antenna without the need for an intervening amplifier in between the antenna connection point and receiver. An advantage of using a metallic coating is that a large area of surface of the glass sheet can be made to function as an antenna, thereby improving signal reception.

Figure 5 shows a plan view of an antenna assembly comprising a vehicle rooflight 50 having a sheet of glazing material 7 that is a single sheet of toughened float glass. Bonded to the inner surface is an electrically conductive coating 54 extending along the transverse centre axis of the glass sheet. The coating 54 is in electrical communication with antenna connection point 11. The antenna connection point may be located in the centre of the rooflight glazing, although this position is not preferred.

Figure 6 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 60 having a sheet of glazing material 7 and a printed silver ink line 64 bonded to the inner surface of the sheet of glazing material. The sheet of glazing material is a sheet of toughened float glass. The silver ink line is in electrical communication with antenna connection point 11. By using a configuration for the electroconductive element that does not extend along the longitudinal or transverse axis of the sheet allows the provision of a longer antenna with an improvement in signal reception. This configuration may also avoid nulls in the polar pattern which can occur if an antenna is exactly on an axis of symmetry of a vehicle when the rooflight glazing is installed in the roof of the vehicle.

Figure 7 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 70 having a sheet of glazing material 7 that is a sheet of toughened float glass and an electrically conductive coating 74 bonded to the inner surface thereof. The coating 74 is in the shape of a letter 'H'. The coating may be in the form of other indicia, for example a logo or trade mark. The coating is visible from the outside of the vehicle. The coating is in electrical communication with antenna connection point 11. The antenna connection point may be located near the end of any of the arms of the letter 'H'. Figure 8 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 80 having a sheet of glazing material 7 that is a sheet of toughened float glass and an electroconductive element 84 in the form of four substantially parallel wires 84a, 84b, 84c and 84d extending along the longitudinal axis of the sheet. The wires 84a, 84b, 84c, 84d may be on the inner or outer surface of the glass sheet. The wires may be screen printed electrically conductive ink, such as a silver containing ink. An antenna connection point 11 is in electrical communication with the four wires 84a, 84b, 84c and 84d. The wires may be configured to perform another function other than that of an antenna, such as providing the vehicle rooflight glazing with a heated area.

Figure 9 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 90 having a sheet of glazing material 7 that is a sheet of toughened float glass and an electroconductive element 94 in electrical communication with antenna connection point 11. The electroconductive element has two straight wires 94a and 94b in the shape of a 'V diverging away from the antenna connection point. The wires are bonded to the glass sheet. The wires 94a, 94b may be on the inner or outer surface of the glass sheet. The wires may be screen printed silver ink.

Figure 10 shows a plan view of an antenna assembly comprising a vehicle rooflight glazing 100 having a sheet of glazing material 7 that is a sheet of toughened float glass and an electroconductive element 104 in electrical communication with antenna connection point 11. The electroconductive element is a printed mesh in the centre of the glass sheet on the inner surface thereof. The width of the mesh is about a quarter of the width of the glass sheet. This may provide a higher bandwidth for FM radio reception. The mesh may be screen printed silver ink.

Figure 11 is a cross sectional view of an antenna assembly comprising a vehicle rooflight glazing 110. The rooflight comprises an inner sheet of float glass 112a and an outer sheet of float glass 112b. The glass sheets 112a, 112b may have a similar composition. One or both may be tinted. Bonded to one face of glass sheet 112a is a layer of laminate material 114a. Bonded to one face of the glass sheet 112b is another layer of laminate material 114b. The two layers of laminate material are joined together. A wire 116, for example a copper wire, is disposed in between the two laminate layers. Suitable laminate material is polyvinyl butyral (PVB). There may be one layer of laminate material that has the wire embedded therein. The wire may be embedded in the surface of the layer such that part of the wire is partially exposed or the wire may be embedded substantially within the body of the laminate material.

It also is possible to have only one sheet of laminate material 114a. In this case, after the lamination process, the wire may be embedded in the lamination material so that the wire is facing the surface of glass sheet 112a or 112b.

If the two glass sheets 112a, 112b are clear glass, having about 0.1% by weight ferric oxide, one or both of the laminate layers 114a, 114b may be tinted, such that the overall transmission of the vehicle roofiight when viewed from the inner to outer surface, is less than 70% and has a neutral colour (when measured using a double beam spectrophotometer and Illuminant D65 2° observer angle). The laminate structure may be made using conventional lamination techniques. The advantage of using this type of laminated structure is that the electroconductive element is protected from damage. Such a laminated construction also offers improved intruder resistance.

Figure 12 shows a cross sectional view of an antenna assembly having a vehicle roofiight glazing 120. The roofiight glazing comprises an inner sheet of float glass 122a and an outer sheet of float glass 122b. The glass sheets 122a, 122b may have the same composition. One or both may be tinted. Bonded to one face of glass sheet 122a is a layer of laminate material 124a. Bonded to one face of the glass sheet 122b is another layer of laminate material 124b. The two layers of laminate material are joined together via a layer of an interlayer material 126. The interlay er material 126 has an electroconductive element 128 within the body thereof. The electroconductive element 128 may be on one or both of the major surfaces of the interlayer material 126. A suitable interlayer material is disclosed in US 5,016,934. A similar construction may be made without the two laminate layers 124a, 124b. In such a construction, the interlayer material 126 is bonded directly to the glass sheets 122a, 122b.

Figure 13 shows a cross sectional view of an antenna assembly having a vehicle rooflight glazing 130. The rooflight glazing is a single sheet of plastic 132. Bonded to one face of the plastic sheet 132 is a layer of laminate material 134. In between the bonded faces is a wire 136. Although the wire 136 is shown embedded in the layer of laminate material, the wire may be embedded in the sheet of plastic 132. The advantage of this construction is that the sheet of plastic weighs less than a sheet of float glass of equivalent dimensions, thereby offering a weight saving benefit.

Figure 14 is a cross sectional view of an antenna assembly having a vehicle rooflight glazing 140. The rooflight glazing comprises a sheet of toughened float glass 142. Bonded to one face of glass sheet 142 is a layer of laminate material 144 such as PVB. On the exposed surface of the laminate material is an electroconductive element in the form of a metallic wire 146. The wire may be embedded in the layer of laminate material. The wire 146 may be enclosed in a plastic sheath. In another alternative, the wire may be releasably attached to the surface of the laminate material 144.

Figure 15 is a cross sectional view showing an antenna assembly according to the present invention installed in a vehicle roof. The antenna assembly has a vehicle rooflight 150 and comprises a sheet of tinted float glass 152. The rooflight 150 is fixed into an aperture in the vehicle roof 154 by a suitable adhesive. A sealant 156 extends around the periphery of the sheet of float glass 152 and helps prevent ingress of water (i.e. rain) into the interior of the vehicle. An electrically conductive metal bar 158 is located beneath the roof so that the bar extends along the longitudinal axis of the aperture in the roof. The bar 158 faces the vehicle rooflight glazing 150. The bar is fixed to the vehicle bodywork by electrically insulating plastic holders (not shown). Connected to the bar 158 is a sun visor blind assembly 159. The bar is approximately 100cm long and has low capacitance to the vehicle body. Both these features are desirable for providing good AM reception when the bar is coupled via an antenna connection point (not shown) to a radio receiver without an intervening amplifier. Compared to a conventional rod antenna, unwanted capacitance to the vehicle body is minimal because there is no sheet metal near to the antenna. This antenna provides good FM reception because the bar is horizontally disposed in the vehicle and in Europe and Japan most FM transmitters are horizontally polarized. Shadowing and other negative effects from the metal of the vehicle roof do not seem to occur because the distance from the metal of the roof to the bar is sufficiently large. The bar may be a structural reinforcement member for the vehicle roof. In a different embodiment the bar 158 is directly fixed to the glass sheet.

In the embodiments described herein, the or each sheet of glazing material may be optically transparent or optically opaque. The or each sheet of glazing material may be body tinted. The or each sheet of glazing material may have a coating on a surface thereof to modify the transmission of light through the thickness of the or each sheet. The coating may be a paint.

The embodiments of the present invention provide the technical advantage that an antenna assembly can be produced comprising a vehicle rooflight glazing and an electroconductive element that is configured to function without an intervening amplifier. Compared with windscreen and backlight integrated antenna systems, the present invention provides a much simpler antenna construction. When installed in a vehicle, an antenna assembly according to the present invention produces no additional wind resistance or additional wind noise when travelling in the vehicle. Embodiments of the present invention provide a vehicle antenna that is vandalism proof (compared to a conventional rod antenna) and can be produced at low cost.

Furthermore, electromagnetic interference is less than with similar antennae that are incorporated into a vehicle windscreen or backlight. This is because by incorporating the antenna into a vehicle rooflight, there is sufficient separation between the antenna and cables/other electronic devices (which tend to be located in the front of the vehicle) so that electromagnetic interference is reduced.

Claims

1. An antenna assembly for a vehicle comprising

a vehicle roof glazing comprising a sheet of glazing material,

an electroconductive element facing the vehicle roof glazing, and

an antenna connection point arranged to be in electrical communication with the electroconductive element, the electroconductive element arranged to be in electrical communication with a radio receiver via the antenna connection point,

wherein the electroconductive element is configured to function as an antenna for the reception of radio signals without an intervening amplifier in electrical connection between the antenna connection point and the radio receiver.

2. An antenna assembly according to claim 1, wherein the vehicle roof glazing further comprises a layer of laminate material disposed on one side of the sheet of glazing material.

3. An antenna assembly according to claim 2, wherein the electroconductive element is disposed between the layer of laminate material and the sheet of glazing material.

4. An antenna assembly according to claim 2, wherein the electroconductive element is supported by the layer of laminate material.

5. An antenna assembly according to any of the preceding claims, wherein the electroconductive element is bonded to the sheet of glazing material.

6. An antenna assembly according to any of the preceding claims, wherein the electroconductive element comprises a metallic coating.

7. An antenna assembly according to claim 6, wherein the metallic coating is optically transparent.

8. An antenna assembly according to any of the preceding claims, wherein the electroconductive element comprises an electrically conductive ink.

9. An antenna assembly according to any of the preceding claims, wherein the electroconductive element comprises an elongate bar or a wire.

10. An antenna assembly according to claim 9 when appendant upon claim 4, wherein the wire is embedded in the layer of laminate material.

11. An antenna assembly according to any of the preceding claims, wherein the electroconductive element is configured to extend between opposite edges of the vehicle roof glazing.

12. An antenna assembly according to claim 11 , wherein the electroconductive element is configured to extend along a centre axis of the vehicle roof glazing.

13. An antenna assembly according to any of the preceding claims, wherein the electroconductive element is configured to function as a slot antenna.

14. An antenna assembly according to any of the preceding claims, wherein the length of the electroconductive element is between 50cm and 100cm.

15. An antenna assembly according to any of the preceding claims, wherein the electroconductive element is configured to receive radio waves in at least one of the AM, FM, SW or LW frequency ranges.

16. An antenna assembly according to any of the preceding claims, wherein the antenna connection point is located in the vicinity of the periphery of the vehicle roof glazing.

17. An antenna assembly according to any of the preceding claims, wherein the antenna connection point is attached to the vehicle roof glazing.

18. An antenna assembly according to any of the preceding claims, wherein the sheet of glazing material comprises a sheet of glass that has been produced by a float process.

19. An antenna assembly according to claim 18, wherein the sheet of glass is a toughened sheet of glass.

20. An antenna assembly according to any of the preceding claims, wherein the sheet of glazing material comprises a sheet of plastic material.

21. An antenna assembly according to any of the preceding claims, where the sheet of glazing material is body tinted.

22. An antenna assembly according to any of the preceding claims, wherein the sheet of glazing material has a coating on a surface thereof, to modify the transmission of light through the thickness of the sheet of glazing material.

23. An antenna assembly according to claim 22, wherein the coating comprises a paint.

24. An antenna assembly according to any of the preceding claims, wherein the vehicle roof glazing is optically opaque.

25. A motor vehicle comprising an antenna assembly according to any of the preceding claims.

26. An antenna assembly as hereinbefore described with reference to the accompanying figures.