Patent Application
20110134007
The present invention relates to a flat antenna. More particularly this invention concerns such an antenna as used for example on a motor vehicle.
A flat or surface antenna for use in or on a mobile object, such as for example a truck, car, crane, container, or the like, has a flat base carrying at least one antenna radiator. The base in turn is mounted on or in a plastic housing.
Surface antennas, also referred to as patch antennas or flat panel antennas, are basically known. An antenna is known under the product name “Orbmaster” from the company Multiband Technologies that operates in the frequency ranges for Orbcomm, mobile radio telephone service and satellite navigation. This antenna comprises a flat base on which two antenna radiators for the frequency ranges are mounted, the base itself being mounted in a plastic housing. The disadvantages in the operation of this antenna are to be seen in that the material of the flat base is not durable and does not meet automotive vibration requirements, and the antenna, in particular in the frequency range for Orbcomm, has a gain of only −9 dBi.
It is therefore an object of the present invention to provide an improved flat antenna for mobile use.
Another object is the provision of such an improved flat antenna for mobile use that overcomes the above-given disadvantages, in particular that is improved over the prior art and in particular has improved durability as well as higher gain and thus better performance.
A surface antenna for mobile use according to the invention has a flat fiberglass base having a thickness of between 7.62 mm (0.300 in) and 12.70 mm (0.50 in), and at least one radiator on the base.
The use of fiberglass, that is glass-fiber reinforced plastic, as a flat base has the advantage that better gain and thus better performance can be achieved. To this end, the base is designed to be larger in length as well as in width than the surface antenna from the prior art. This results in a gain of at least −4 dBi, a clear improvement over the gain of the surface antenna from the prior art. The thickness used in the range between 7.62 mm and 12.70 mm (0.3 inches to 0.5 in) has the advantage that this thickness, which is preferably 9.5 mm (0.375 in), is a very good compromise on the one hand with respect to the bandwidth of the surface antenna to be achieved and on the other hand to the its stability, since it is used in objects such as, for example, vehicles with high shock loads and vibration loads and the weight of the antenna. A thinner material with thicknesses less than 7.62 mm has the disadvantage that the antenna would be too narrow-band and the Orbcomm frequencies would not be covered. A thicker material with a thickness of greater than 12.70 mm has the disadvantage that the entire surface antenna would reach a material volume that is too high and, associated therewith, a weight that is too high.
In a further development of the invention, the base is coated with a metal on its face lying the face carrying the antenna radiator. This coating forms a ground plane for the surface antenna, so that it can easily be used at the installation site in or on the mobile object. This has then in particular the advantage that the installation site of the object, that is, the component thereof, can be made of plastic as well as of metal.
The antenna radiators are formed in a particularly advantageous manner by a coating of the base of fiberglass with a metallic material, the material being preferably copper. This material has the electrical properties necessary here, so that the desired gain and the bandwidth to be achieved of the surface antenna can be thus achieved particularly well. Coating of the regions that form the antenna radiators on the base can either be printed (for example with an electrically conductive paste, preferably a copper paste) or are produced by etching, where initially the one surface of the base on which the antenna radiators are to be mounted are coated completely with a metallic material and subsequently those regions that do not form the antenna radiators are etched away. It is also possible to make the antenna radiators, that is the electrically conductive regions, by applying preshaped metallic flat antenna elements to an electrically nonconductive support such as a plastic board.
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
As shown in
As mentioned above, so that the surface antenna 1 is flat, the thickness of the base 2 is no more than 12.70 mm. Furthermore to get the desired improved gain, this base 2 has a length L of at least 488 mm (19.2 in) and no more than 732 mm (28.8 in) as well as a width B of at least 365 mm (9 in) and no more than 548 mm (21.6 in). The very particularly preferred dimensions of the base 2 are 457 mm in width (18 in), 610 mm in length (24 in) and 9.5 mm in thickness (0.375 in).
In a further embodiment of the invention, the antenna radiator 32 is rectangular, in particular square, and shaped for transmitting and/or receiving mobile radio telephone service signals. Also, to increase gain and bandwidth of this antenna radiator 32, it has at least one slot 36, preferably four slots 36, which, as shown in
In a third embodiment of the invention, the antenna radiator 33 is rectangular, in particular square and for transmitting and/or receiving WLAN signals.
For feeding signals that are to be emitted via at least one of the antenna radiators 31, 32, or 33, or signals that are to be received by these antenna radiators 31 through 33, terminal 37 are provided whose positions on the flat base 2 are shown in the drawing.
At the top on the right in
At the top on the right in
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 102008063802.1 | Dec 2009 | DE | national |
