Layout for automotive window antenna

#The present invention relates generally to a layout for an antenna. More particularly, the present invention relates primarily to a layout for a radio frequency (RF) antenna. An example of a RF antenna is a window antenna for a vehicle or other automotive means.

#Modern automotive means may need an antenna to support RF communication. A number of devices may function using RF communication. For instance, AM radios, FM radios, AM/FM radios, CB radios, cellular phones, and global positioning systems are dependent on RF communication.

#A modern automobile may have a glass window that serves as a dielectric support for a wire pattern layout of a RF antenna. Typically, a rear window is used for such purposes. A pattern of wires printed or imbedded in the glass (i.e., printed lines) may permit RF current flow to and from the desired RF device.

#FIG. 1 is a schematic diagram showing the typical direction of RF current flow throughout a vehicle body.

#FIG. 2 is a schematic diagram of one exemplary embodiment of a wire pattern layout of the present invention.

#FIG. 3 is a schematic diagram of one exemplary embodiment of a wire pattern layout of the present invention.

#The present invention is directed to a layout for an antenna. The present invention will be described primarily herein with regard to a RF antenna embodiment for an automotive window. However, the present invention is not limited to that particular embodiment. The present invention may be useful for frequencies outside (i.e., above or below) of the RF range. Accordingly, the present invention is not limited to use with RF devices such AM and FM devices. Also, the wire pattern layout of the present invention may be supported or otherwise suspended in any suitable dielectric material including, but not limited to, windows and other glass objects, plastics, air, or any other similar, suitable, or conventional dielectric material. Examples of glass include, but are not limited to, safety glass and fiberglass. Examples of plastics include, but are not limited to, polycarbonate and plexiglass. Furthermore, the present invention is not limited to a layout of an antenna for a vehicle or other automotive means. The present invention may be useful for any type of antenna application. As used herein, the term wire shall be understood to include printed lines of conductive material, rigid filaments or rods of conductive material, flexible filaments or rods of conductive material, and other types of electrical conductors that are encompassed within the conventional meaning of the term wire.

#FIG. 1 is a schematic view which shows that a vehicle body may have an impact on the design of the wire pattern layout of an antenna. FIG. 1 shows a roof panel 10 that is situated adjacent to a window 12. A metal panel 14 is secured to the window 12. The metal panel 14 is in electrical communication with an antenna feed 16. Theoretical equipotential lines 18 are shown for illustration purposes. In such an embodiment, RF current in the AM and FM frequency bands flows radially from the feed 16 as indicated by arrows 20. As a result, the entire body of the vehicle essentially becomes a part of the antenna as the RF current flows throughout the metal panels of the vehicle body. Accordingly, the present invention takes this phenomenon into account in the design of the wire pattern layout of antenna. Consequently, exemplary embodiments of the present invention exhibit improved pattern control and impedance matching over the desired frequency band as compared to traditional wire pattern layouts.

#FIG. 2 shows one embodiment of a wire pattern layout of the present invention. In FIG. 2, a roof panel 22 is situated adjacent to a window 24. A grid of approximately horizontal power wires 26 extend across the window. For example, the power wires 26 may function as heating elements by conducting DC current, thereby defogging or defrosting the window 24. An antenna feed 28 is in electrical communication with at least one antenna wire 30. In this example, a plurality of antenna wires 30 traverse the power wires 26. The antenna wires 30 of this embodiment include a plurality of oblique lines and one line that is approximately perpendicular to the power wires 26. Accordingly, this embodiment of the wire pattern layout is an efficient and improved antenna design because it accommodates the natural direction of RF current flow.