Patent Description:
Field: The present disclosure relates to an antenna.

Background: With the growth of wireless communications and the proliferation of wireless communication devices and systems, antennas have found broad implementation as a result of their favorable properties and relatively simple design and fabrication. One form of antenna known as a slot antenna comprises a thin flat metal layer with one or more holes or slots removed. A feed line can be connected to the thin flat metal layer and either driven by connected transmitter circuitry at a required frequency or frequencies; or the feed line can be connected to a receiver tuned to pick up a signal at a required frequency or frequencies from the layer; or the feed line can be connected to both receiver and transmitter circuitry; or the feed line can be connected to transceiver circuitry. Typically, a coaxial feed line is attached to the surface of the antenna via manual solder-bonding. Even relatively slim coaxial feed lines can vary in diameter from about <NUM> to <NUM> and so comprise the major portion of the thickness of the antenna, the remainder comprising the thickness of the layer itself.

One potential application for antenna devices is within a window panel such as a windshield of an automotive vehicle, although it will be appreciated that there may be many other applications where only limited clearance is available for incorporating an antenna. Typically, such windshields are fabricated by laminating at least <NUM> layers of glass with a layer of plastic material in between the two glass layers. Such windshields may provide a gap of about <NUM> between the layers of glass and this gap can be utilized for integrating a windshield heating element, amplitude modulation (AM), frequency modulation (FM) antenna elements or both AM and FM antenna elements. The fabrication process of an automotive vehicle windshield exposes the layers of glass to high pressures and high temperatures, and such fabrication conditions need to be taken into account when designing an in-glass high performance antenna for integration between the layers of glass of the windshield.

In order to feed such antennas with a transmission line, such as a coaxial feed line, a feed line would need a diameter significantly less than <NUM>. However, it will be appreciated that as the diameter of a coaxial feed line reduces, performance issues and increases in losses within the cable occur, thereby affecting the transmission of signals propagating through the coaxial feed line. Additionally, the high pressure and high temperatures that a windshield is exposed to during the manufacturing process can damage and impact the integrity of a larger coaxial cable in particular.

Thus, there is a need for a low profile, high performance antenna capable of being incorporated, for example, within an automotive vehicle window panel, and with an associated feed line that can withstand the windshield fabrication environment without negatively affecting the performance of the antenna after installation. <CIT> describes various aspect and embodiments of a modular wideband antenna element, wherein the antenna element includes a support structure comprising a feed network and first and second arbitrarily- shaped radiator elements extending along a main axis of the antenna elements. <CIT> describes an antenna device which includes a substrate, a through hole, first and second grounded conductors, a radiating element and a feeder line. <CIT> describes an antenna module which includes a resin multilayer substrate including a plurality of base materials that are flexible. <CIT> describes a Vivaldi-Monopole antenna which is a small form ultra-wideband antenna configured for low frequency operation in modern wireless devices. <CIT> describes a flat-conductor connection element for an antenna structure. <CIT> describes a slot for a decade band tapered slot antenna, and a method of making and configuring same, wherein an antenna apparatus includes an antenna element that has conductive material with a recess therein. <CIT> describes an antenna assembly including a first antenna element and a second antenna element, wherein at least one of the antenna elements includes a transparent layer. <CIT> describes a flat cable, a flat cable sheet, and a flat cable sheet producing method.

The invention is set out in the independent claim. An aspect of the disclosure is directed to a window panel having high performance antennas incorporated in glass, between glass layers. Suitable antennas comprise: a radiating element; a ground plane element; and a transmission line extending across at least a portion of the radiating element and the ground plane element, the transmission line comprising: a dielectric layer, the dielectric layer having a portion of a first surface adjacent to the ground plane element and a second major surface opposite and separated from the first surface; a shield formed on the second major surface; a via extending through the dielectric layer to connect the shield to the ground plane element; a feed line extending longitudinally through the dielectric layer from a feed point at a proximal end of the transmission line towards a distal end of the transmission line, the feed line being shielded along a portion of the feed line length that extends across the ground plane element by the shield with the distal end of the transmission line being conductively connected with the radiating element and coupling the feed line to the radiating element. The radiating element and the ground plane element define a slot therebetween. Additionally, the radiating element and the ground plane element are further configurable to define an aperture and a tapered channel connected by the slot therebetween. Further, an outer shape of the antenna radiating element and the ground plane can comprise, for example, a rectangle. Additionally, the transmission line can be configured to straddle the slot. In some configurations, the feed line straddles the slot. The dielectric layer can further be configurable to comprise at least one of a flexible material and a rigid material. Suitable antennas can be selected from the group comprising: a Global Navigation Satellite System (GNSS) antenna, an LTE antenna, a <NUM> antenna, a DSRC antenna, a Bluetooth antenna and a Wi-Fi antenna. The distal end of the feed line is configured to connect to the radiating element through a via. In at least some configurations, the feed line comprises any one or more of a stripline, a microstrip, a co-planar waveguide and a co-planer waveguide with ground. The distal end of the transmission is supported by at least a portion of the dielectric layer. The antenna radiating element and co-planar ground plane element can also be formed of a metallic material comprising copper, aluminum, gold, or silver. A pair of vias can be provided straddling the feed line. In some configurations, a plurality of pairs of vias can be provided which are distributed along a length of the feed line.

The same aspect of the disclosure is directed to window panels having one or more antennas. Suitable configurations comprise: a first glass layer and a second glass layer; wherein the one or more antennas are incorporated between the first glass layer and the second glass layer with a respective one or more transmission lines extending from between the first glass layer and the second glass layer for connecting the one or more antennas to a communications module. The first glass layer and the second glass layer can also be laminated together with a plastic layer therebetween. Additionally, the radiating element and the ground plane element for the one or more antennas can be formed directly on a glass layer or a laminated substrate of the window panel. The one or more antennas can also be pre-fabricated before incorporating between the first glass layer and the second glass layer. When the antennas are pre-fabricated, the antennas can be pre-fabricated on a common substrate. The window panel can be, but is not limited to, a vehicle windshield.

<CIT> for Disconnectable microstrip to stripline transition;.

<CIT> for Dual band slot antenna with single feed line;.

<CIT> for Method, system and apparatus for an antenna;.

<CIT> for RFID patch antenna with coplanar reference ground and floating grounds;.

<CIT> for Planar array antenna having antenna elements arranged in a plurality of planes;.

<CIT>, for Method for creating a slot-line on a multilayer substrate and multilayer printed circuit comprising at least one slot-line realized according to the method and using an isolating slot antenna;.

<CIT> for Antenna assembly for electronic device;.

<CIT> for Stripline coupled antenna with periodic slots for wireless electronic devices;.

Referring now to <FIG>, some steps of an exemplary method for fabricating an antenna <NUM> of <FIG> according to the disclosure are illustrated. In <FIG>, there is shown a first substrate 104A wherein a first side of the first substrate 104A is coated with a conductive material <NUM>. The first substrate <NUM> A is illustrated with a rectangular shape having a first side <NUM>, a second side <NUM>, a third side <NUM>, and a fourth side <NUM>. Examples of conductive material <NUM> suitable for coating the first substrate 104A include, but are not limited to, a glass-reinforced epoxy laminate such as fiberglass resin (FR4) and Kapton® polyimide film available from Dupont, while suitable conductive materials include copper, aluminum, gold or silver.

During the fabrication process, the conductive material <NUM> is masked to define an antenna configuration/shape and then etched to remove portions of the conductive material <NUM> that does not form part of the antenna. As shown in <FIG>, where the first substrate 104A is a flipped view of <FIG>, the antenna configuration/shape comprises a radiating element <NUM> generally separated from a ground plane <NUM> by a tapered channel <NUM>, slot <NUM> and an aperture <NUM> with a strip comprising a transmission line base layer <NUM> for a transmission line extending from a side <NUM>' of the ground plane <NUM> of the antenna. As shown in <FIG>, the first side <NUM> of the first substrate 104A is not coextensive with the first side <NUM>' of the ground plane <NUM>. As will be appreciated by those skilled in the art, any variety of antenna shapes can be defined at this stage of the process, but it is desirable in each case to provide for a transmission line <NUM> extending from a side of the antenna to facilitate connection of the antenna to receiver/transmitter/transceiver circuitry.

In the next step, shown in <FIG>, the first substrate 104A is patterned to remove all but a layer of dielectric material to leave a first substrate remainder 104B portion extending along the length of the transmission line base layer <NUM>, across the ground plane <NUM> and, in the present example, traversing the slot <NUM> and extending partly over the radiating element <NUM>. It will be appreciated that at this stage, the conductive material <NUM> may be a patterned layer that is quite fragile and so a temporary carrier (not shown) can be provided to support the ground plane <NUM> of the radiating element <NUM> from its surface opposite the first substrate remainder 104B portion during subsequent processing.

Referring now to <FIG>, in order to complete the assembly of the antenna <NUM>, a second substrate <NUM>, such as a dielectric substrate layer, having a first side coated with a conductive material which is a shield <NUM> is provided. The second substrate <NUM> corresponds in shape with the first substrate remainder 104B shown in <FIG> except that it is marginally shorter as illustrated in <FIG>.

Before the second substrate <NUM> is combined with the first substrate remainder 104B, a feed line <NUM> is located between the substrates, the feed line <NUM> running longitudinally along the first substrate remainder 104B from a first substrate remainder distal end remote from the ground plane <NUM> to a proximal point where the first substrate remainder 104B overlies the radiating element <NUM>. The three components can now be bonded using any of: adhesive, pressure, or adhesive and pressure possibly in combination with another other technique to provide a nascent shielded transmission line <NUM>.

In <FIG>, two pairs of vias <NUM> are shown with each pair straddling the feed line <NUM>. However, it will be appreciated that in variants of the embodiment, any number of vias, pairs of vias or arrangements of vias can be formed along the length of the transmission line <NUM>, as required. It will also be appreciated that these vias once complete can maintain the first 104B and second <NUM> substrates together and so the original bonding of the substrates may only need to be suitable for temporary bonding.

An end via <NUM> can be formed towards the end of the first substrate remainder 104B to electrically connect the feed line <NUM> to the radiating element <NUM>. Nonetheless, it will be appreciated that in variants of the embodiment, no via may be required and in this case, the end of the feed line would only be coupled to the radiating element. In either case, the first substrate remainder 104B need not extend across either the slot <NUM> or the radiating element <NUM> i.e. the slot <NUM> could be co-terminus with the second substrate <NUM>.

Referring back to <FIG>, as described, the antenna <NUM> comprises a radiating element <NUM>, a ground plane <NUM> (which can be a co-planar ground plane element), and a transmission line <NUM>. A feed line <NUM> is also provided which spans a centerline CL of the slot <NUM> at a right angle, the feed line <NUM> extends across at least a portion of the ground plane <NUM> and the radiating element <NUM> by a distance d1. As illustrated, the outer shape of the antenna <NUM> is rectangular having a first side <NUM>, a second side <NUM>, a third side <NUM>, and a fourth side <NUM>, numbered clockwise as viewed in the illustration. The slot <NUM> is arranged so that the longitudinal centerline CL of the slot extends parallel to the first side <NUM> and the third side <NUM>. Note that the centerline CL may be positioned off center along the length of the first side <NUM> and the third side <NUM>. An aperture <NUM>, depicted as a circular aperture, is provided at one end of the slot <NUM> within the body of the antenna <NUM> with the aperture <NUM> of the slot <NUM> straddling the centerline CL. A tapered channel <NUM> extends from the slot all the way to the third side <NUM>. When the aperture <NUM> is a circular aperture, the aperture <NUM> can have a diameter up to approximately half the length of either the first side <NUM> or the third side <NUM>. The tapered channel <NUM> is narrowest where the tapered channel <NUM> meets the slot <NUM> and gradually widens as the tapered channel <NUM> approaches the third side <NUM>. Note that the slot <NUM> does not need to have parallel sides and in one embodiment the width of the slot <NUM> at its narrowest point adjacent the aperture <NUM> is approximately <NUM>% the diameter of the aperture <NUM>, while, at its widest point before the slot <NUM> expands into the tapered channel <NUM>, the width of the slot <NUM> is approximately <NUM>% the diameter of the aperture <NUM>. Thus, the configuration of the slot <NUM> is typical for a slot antenna. The transmission line <NUM> straddles the slot <NUM> near the point on the antenna <NUM> where the slot <NUM> meets the aperture <NUM>. In the embodiment, the transmission line crosses the center line of the slot <NUM> at a right angle.

The transmission line <NUM> comprises the second substrate <NUM>, a feed line <NUM> which extends longitudinally through the dielectric substrate layer from a feed point at a distal end of the transmission line towards the end overlying the radiating element <NUM>. In one embodiment, the feed line <NUM> arrangement comprises a conductive metal stripline. The feed line <NUM> may be provided resting atop the transmission line of the second substrate <NUM> thus forming, for example, a microstrip. The microstrip may have additional conductive metal strips running alongside and adjacent to the feed line <NUM> microstrip thus forming a co-planar waveguide or a co-planar waveguide with ground. In the embodiment depicted, the feed line <NUM> runs along the entire length and has a thickness approximately one eighth that of the second substrate <NUM>. Visible in <FIG>, are the top surfaces of a plurality of transmission line vias <NUM>. The transmission line vias <NUM> are composed of a suitable electrically conductive material. The transmission line vias <NUM> extend through the second substrate <NUM> to connect the shield <NUM> to the ground plane <NUM> so as to provide an electrically conductive connection on one side of the tapered channel <NUM> between the shield <NUM> and the ground plane <NUM>. Although not shown, the plurality of transmission line vias <NUM> will extend from the vias as shown in <FIG> along the length of the transmission line towards a proximal end of the transmission line.

The transmission line <NUM> may be in the form of a microstrip that runs within the second substrate <NUM> along the entire length of the transmission line <NUM>. Like the feed line <NUM>, the microstrip is composed of a conductive metal material. The transmission line <NUM> is approximately one quarter as wide as the second substrate <NUM> and has a thickness approximately one eighth that of the second substrate <NUM>. The transmission line <NUM> is centered within the width of the second substrate <NUM> of the transmission line and is approximately centered within the thickness of the second substrate <NUM>.

<FIG> depicts a cross-section illustrating a portion of the internal details of the connection of the transmission line <NUM> to the radiating element <NUM> and ground plane <NUM>. The feed line <NUM> is depicted as extending across at least a portion of the radiating element <NUM> and the ground plane <NUM> straddling the slot <NUM> near the point (not shown) on the radiating element <NUM> where the slot <NUM> meets the aperture <NUM> shown in <FIG>. Also visible in <FIG>, are two of the transmission line vias <NUM> extending through the second substrate <NUM> to connect the shield <NUM> to the ground plane <NUM>. Once assembled, a number of vias <NUM> can be formed along the length of the transmission line to electrically connect the shield <NUM> to the transmission line base layer <NUM> and thus the ground plane <NUM>.

Also, a portion d of transmission line <NUM> comprises only the first substrate remainder 104B portion and with an exposed section of feed line 142A extending across at least a portion of the ground plane <NUM> and radiating element <NUM> terminating at slot <NUM>. The first substrate remainder 104B in the portion d of the transmission line is optional and provides support for the feed line 142A that extends across at least the portion d1 of the radiating element <NUM> and at least the portion d2 of the ground plane <NUM>.

A microstrip via <NUM> is formed adjacent microstrip near an end of the feed line <NUM> and completes the conductive connection from the feed line <NUM> to the surface of the radiating element <NUM>. The microstrip via <NUM> connects to the surface of the radiating element <NUM> on the side of the tapered channel <NUM> opposite that which the vias <NUM> connect. Although <FIG> illustrates the via <NUM> extending from the microstrip <NUM> to the radiating element <NUM>, the transmission line <NUM> can also be configured such that a distal end of transmission line <NUM> lies space apart from and in register with the radiating element <NUM> electromagnetically coupling the feed line <NUM> to the radiating element <NUM>.

In operation, connecting the transmission line <NUM> to a voltage source induces a voltage across the tapered channel <NUM>, slot <NUM> and the aperture <NUM> which, in turn, creates an electric field distribution around the slot (not shown).

As can be seen in <FIG> and <FIG>, once completed, the transmission line <NUM> can be bent at a point along its length away from the ground plane. In <FIG>, the bend is shown at the edge of the ground plane <NUM>, but as will be appreciated by those skilled in the art, a bend at the edge of the ground plane <NUM> is not the only suitable location for a bend. Bending the transmission line in this manner enables the body of the antenna to be located within for example the laminated layers of a window panel (as explained below) while connecting to electronics components which may lie out of the plane of the window panel.

Turning now to <FIG>, a simulated return loss <NUM> of the antenna <NUM> shown in <FIG> is illustrated, the return loss is plotted across the frequency domain from <NUM> gigahertz (GHz) to <NUM>. The plot is typical of a slotted antenna of the configuration described in the embodiment presented in <FIG>. The simulated return loss <NUM> consists of a series of continuous concave-down quasi-parabolic shapes spanning the range from <NUM> to <NUM>. The maxima range from <NUM> decibel (dB) at <NUM> to approximately -<NUM> dB at approximately <NUM>. The minima range from approximately -<NUM> dB at approximately <NUM> to approximately -<NUM> dB at approximately <NUM>.

<FIG> is a plot of the simulated total efficiency <NUM> of the antenna <NUM> illustrated in <FIG> across the frequency domain from <NUM> to <NUM>. The plot is typical of a slotted antenna of the configuration described in the embodiment presented in <FIG>. The simulated total efficiency <NUM> exhibits a local maxima of approximately <NUM>% at <NUM> and <NUM>% at <NUM>.

The embodiment depicted in <FIG> illustrates a specific configuration of a slot antenna. Thus, the antenna <NUM> produced according to the above example is a Vivaldi slot antenna. In some examples not forming part of claimed invention, the disclosure is applicable to any antenna design which can be implemented with a planar conductor including for example a monopole antenna, dipole antenna. According to some embodiments, the antenna may be a Dedicated Short-Range Communications (DSRC), Global Navigation Satellite System (GNSS) antenna or Wi-Fi antenna.

<FIG> illustrate the placement for a variety of antenna configurations including antenna <NUM> in <FIG>, antenna <NUM>' in <FIG>, and antenna <NUM>" in <FIG> according to various embodiments of the present disclosure in a windshield <NUM> of an automobile. <FIG> shows a location for the antenna of <FIG> within the windshield <NUM>, with <FIG> showing an alternative location for the antenna <NUM>' which is a variant of the antenna <NUM> illustrated in <FIG> within the windshield <NUM> and <FIG> showing a further alternative location for another antenna <NUM>" which is a variant of the antenna <NUM> shown in <FIG> within the windshield <NUM>. Multiple antennas can be located in the windshield <NUM>. The antennas can be a combination of different types of antennas. The placement of the antennas are provided for illustrative purposes and provided by way of example only and are not limiting. <FIG> illustrates antenna <NUM>" shown in <FIG> in more detail. The antenna <NUM>" has a radiating element <NUM>", a ground plane <NUM>", and a transmission line <NUM>.

<FIG> shows a cross-section view of the antenna of <FIG> in-situ within a windshield <NUM>. The windshield <NUM> comprises at least two glass layers, first glass layer 200A and second glass layer 200B, with an antenna located between the first glass layer 200A and second glass layer 200B. Located on a first surface of one of the first glass layer 200A is a plastic layer <NUM> and located on a surface of the plastic layer, the surface being that surface which is opposite surface that is adjacent to the first glass layer 200A, is the antenna of <FIG> or a variant of the antenna shown in <FIG> or <FIG>. A ground plane <NUM>, is adjacent the plastic layer <NUM> on one side and the first substrate 104A. The remainder of the first substrate 104A is adjacent the feed line <NUM>. The feed line <NUM> is adjacent the second substrate <NUM>, and the shield <NUM> is positioned between the second glass layer 200B and the second substrate <NUM>.

<FIG> shows an antenna <NUM> located between the first glass layer 200A and the second glass layer 200B of a windshield <NUM> and connected to a communications module including driver circuitry <NUM>. The antenna <NUM> is connected to the driver circuitry <NUM> by the transmission line <NUM>, the distal end 140A of the transmission line being connected to the antenna and extending from between the first glass layer 200A and second glass layer 200B of the windshield <NUM> for connecting to the driver circuitry <NUM> external to the windshield.

As will be appreciated by those skilled in the art, while the antennas <NUM>, <NUM>' and <NUM>" have been described as being provided as a pre-fabricated sub-assembly module fitted on a glass or laminated substrate of a window panel, such as a windshield, for subsequent incorporation within the window panel, it is also possible, to produce antenna traces for more than one antenna on a given substrate and for these to be connected to separate feed lines.

Also, it is possible to print the traces for one or more antennas directly on a glass or laminated substrate of the window panel before fixing the transmission line to the traces and subsequent incorporation within the window panel. Referring to <FIG>, a windshield <NUM> is illustrated incorporating a dipole LTE antenna 900A, a GNSS antenna 900B, a Wi-Fi antenna 900C and a DSRC antenna 900D, each with one or more respective feed lines 142A. '142B converging on a connector <NUM>. In the case of the GNSS antenna 900B and DSRC antenna 900D, a pair of feed lines are connected directly to the cross-dipole antenna traces and these are connected to the connector <NUM> via respective couplers 930B, 930D. Note that the feed lines are shown schematically, in practice, are likely to converge close to a common point on the edge of the windshield where they are fed to the connector <NUM>.

Referring now to <FIG>, in one such arrangement a set of <NUM> antennas including a DSRC patch antenna 900E (instead of the cross-dipole of <FIG>), a Wi-Fi antenna 900C, a GNSS antenna 900B' and a dipole LTE antenna 900A are constructed on a common substrate <NUM> which is located along an edge <NUM> of a window panel within a blacked out region towards the edge of the window panel. In this case, both feed lines of the GNSS antenna 900B' are connected directly to a connector <NUM>' (without a discrete coupler <NUM> as in <FIG>).

In order to provide an idea of the scale of these devices, in the direction W shown, the dipole LTE antenna 900A is approximately <NUM> wide, the GNSS antenna 900B' is approximately <NUM> wide, the Wi-Fi antenna 900C is approximately <NUM> wide and the DSRC patch antenna 900E is approximately <NUM> wide.

Claim 1:
A window panel having an antenna (<NUM>), wherein the antenna (<NUM>) comprises:
a radiating element (<NUM>);
a ground plane element (<NUM>); and
a transmission line (<NUM>) extending across at least a portion of the radiating element and the ground plane element, the transmission line comprising:
a dielectric layer (104B, <NUM>), the dielectric layer having a portion of a first surface adjacent to the ground plane element and a second major surface opposite and separated from the first surface;
a shield (<NUM>) formed on the second major surface;
a via (<NUM>) extending through the dielectric layer to connect the shield to the ground plane element;
a feed line (<NUM>) extending longitudinally through the dielectric layer from a feed point at a proximal end of the transmission line towards a distal end of the transmission line, the feed line being shielded along a portion of a length of the feed line that extends across the ground plane element by the shield with the distal end of the transmission line being conductively connected with the radiating element through a microstrip via (<NUM>) and coupling the feed line to the radiating element;
wherein the radiating element and the ground plane element define a slot (<NUM>) therebetween; and
wherein the radiating element and the ground plane element further define an aperture (<NUM>) and a tapered channel (<NUM>) connected by the slot therebetween, wherein an outer shape of the radiating element and the ground plane element preferably comprises a rectangle;
wherein the window panel comprises:
a first glass layer (200A) and a second glass layer (200B);
wherein the antenna is incorporated between the first glass layer and the second glass layer with the transmission line extending from between the first glass layer and the second glass layer for connecting the antenna to a communications module.