The invention relates to a protective antenna cover (ESD cover), for example in shell form, that is formed as a loop radiator and is in particular composed of dielectric plastic, for the reception of circularly polarized satellite radio signals.
Such a reception takes place in the example of SDARS satellite radio at a frequency of approximately 2.33 GHz having the free space wavelength A=12.8 cm in two adjacent frequency bands each having a bandwidth of 4 MHz at a spacing of the center frequencies of 8 MHz. The signals are irradiated from different satellites with an electromagnetic wave circularly polarized in one direction. Similar satellite radio systems are currently in planning. Circularly polarized antennas in the corresponding rotational direction are accordingly used for the reception. The satellites of the global positioning system (GPS) likewise radiate waves circularly polarized in one direction at the frequency of approximately 1575 MHz so that said antenna shapes can generally inter alia also be designed for this service.
Such antennas are preferably used on a vehicle roof for the mobile reception of circularly polarized satellite signals of the satellite radio services SDARS or XM or e.g. the GPS navigation system in vehicles. The metal vehicle roof here frequently serves as an expanded electrically conductive base surface for such antennas. Provision is likewise made to accommodate an antenna for the reception of circularly polarized satellite radio signals beneath a shell-shaped protective antenna cover composed of dielectric plastic. The opening side of the shell is here covered by an electrically conductive base plate that is mechanically connected to the protective antenna cover and that can be positioned with a substantially horizontal orientation on the outer skin of a motor vehicle.
Such a loop radiator is known from DE 10 2009 040 910 and is shown as prior art in
The known satellite antenna shown in
What is decisive for the acceptance of the technology of antenna for vehicles is, in addition to the functionality of the antenna, above all the economic effort that is associated both with the manufacture of the antenna and also with its implementation on the vehicle.
Due to the very tight tolerances in directional radiation patterns of satellite antennas, the tolerances for the manufacture of such antennas are extremely small. The observation of not only the mechanical dimensions, but also of the dielectric properties of the antenna body is equally a problem with circularly polarized antennas that work in accordance with a different principle of action such as patch antennas. In particular the observation of the mechanical dimensions is of special importance in the present loop radiator.
The storage of the loop radiator cut from sheet metal and subsequently bent as a mass produced product in mass production is also problematic. A storage of the sheet metal structure maintaining its shape is extremely complex and/or expensive and a harmful deformation of the structure by handing can only be avoided with great difficulty due to the tight tolerances.
These demands on the accuracy naturally result in increased manufacturing costs for the antennas.
The object is therefore associated with the present invention of designing an antenna for the reception of circularly polarized satellite radio signals that enables a simpler implementation on the vehicle with a high functional reliability and with a small economic effort.
This object is satisfied by the features of claim 1.
Advantageous embodiments of the invention are described in the dependent claims and in the description.
The protective antenna cover can be positioned above an electrically conductive base plate that is mechanically connected to it, that covers the opening of the protective antenna cover and that is to be positioned on an outer skin of a motor vehicle in a substantially horizontal orientation. The opening of the protective antenna cover can also be closed by a film or plate, that is in particular dielectric and that is in particular positioned in the reference plane.
The protective antenna cover can be provided with at least one loop radiator that is formed by a closed loop arranged extending at a spacing h in parallel with the conductive base plate and that has linear, substantially vertical, radiators connected distributed at the periphery of the loop and extending toward the conductive base plate. In this respect, a linear radiator or a vertical radiator is understood in accordance with the invention as a linear radiator that is connected to the loop and that does not necessarily extend away from the plane of the loop at an angle of 90°. The vertical radiators in accordance with the invention can rather also extend in the direction of the electrically conductive base plate or in the direction of the reference plane formed by the opening of the protective antenna cover at an angle differing from 90°. A linear radiator in accordance with the invention also does not necessarily have to have the shape of a straight line. The term linear radiator is rather seen in accordance with the invention as a delineation from the loop radiator that forms a closed (round or angled) loop shape. In contrast, the linear radiators in accordance with the invention extend away from the loop in the direction of the opening of the protective antenna cover. It is therefore understood that the linear radiators can also be formed as curved if the protective antenna cover, for example, has a dome-shaped design.
The protective antenna cover can generally be configured as desired, for example in a shell shape, a dome shape or a pyramid shape, or also as a combination of these shapes. The protective antenna cover, however, preferably has part surfaces at its inner side which are electrically conductively coated and whose shape is adapted to the function of the components of the loop radiator.
At least one of the linear radiators can be capacitively connected at its lower end via a capacitor to the electrically conductive base plate and another linear radiator can be capacitively connected via a capacitor to an antenna connector.
Individual features of the invention can be:
A particular advantage of the invention is given in that the dimensional stability can easily be observed due to the shape of the protective antenna cover 1a pressed into plastic. The properties of modern plastics in particular also have long term stability under extreme weather conditions. The conductive surfaces applied using modern laser technologies or printing techniques to the inner surfaces of the correspondingly preshaped shell-shaped protective antenna cover 1a thus have electrical properties that are constant in the long term. Laser techniques or printing techniques have already provided suitable for mass production. The printing of the electrically conductive layer can be implemented, for example, by a pressure pin for a direct application of the conductive layer or, for example, by a laser beam. The tip of the pressure pin or the diameter of the laser beam respectively determines the grain fineness of the print and thus the fineness of the structures to be designed.
On a use of a laser, the inner surface of the protective antenna cover can e.g. be covered over a larger area by an electrically conductive layer and above it by a laser-sensitive layer that hardens on exposure to laser light in a manner such that the electrically conductive layer below it and the non-exposed points of the conductive layer are removed in a subsequent etching process.
Finally, it is also possible on the presence of an electrically conductive layer applied over a large area to treat it with a high energy laser beam in a manner such that the non-conductive surface parts of the layer are “lasered free”.
The required solid shape match between the protective antenna cover 1a and the conductive surface 6 can always be established. The complexity in the manufacture of known loop radiators 1 cut from sheet material, subsequently bent, stored in a manner suitable for its shape, and mounted on the conductive base plate 6 in a manner suitable for its shape is extremely reduced with a loop radiator in accordance with the invention.
The capacitors 5a, 5b, 5c, 5d can each be formed in pairs disposed opposite one another by a flat electrode 5a, 5b, 5c, 5d and a flat counter-electrode respectively in parallel therewith. A respective flat electrode 5d that is connected to the lower end of the respective substantially vertical radiator 4d is here applied in a coated manner as an electrically conductive areal structure to a formation of the inner surface of the protective antenna cover 1a formed extending at a spacing 11 from and in parallel with the conductive base plate 6. The capacitance value of the capacitors is determined by the spacing 11.
With a loop radiator 1 in accordance with the prior art in
For the capacitive connection of the at least one of the substantially vertical radiators 4, 4a-d at its lower end to the antenna connector 5 in the plane of the base plate 6, a flat counter-electrode 5e electrically insulated therefrom is formed that is connected to the antenna connector 5.
The marginal line of the opening of the shell-shaped protective antenna cover 1a and the conductive base surface 6 extend in a plane that is defined for the following description in a horizontal location as the reference plane 16 (
To ensure an error-free mold removal on the pressing of the shell-shaped cover, all the flat parts disposed in the interior of the shell-shaped protective antenna cover 1a and all the flat parts disposed on the outer surface of the shell-shaped protective antenna cover 1a can adopt an angle toward the horizontal reference plane 16 of no more than 89.5% as the mold removal slope.
In a manufacturing method, the coating of all the surfaces to be electrically conductively coated can take place with the aid of a needle-shaped jet producing the coating from only one direction (=processing direction 17) that extends substantially perpendicular to the reference plane 16. All the surfaces disposed in the interior of the shell-shaped protective antenna cover and to be coated can adopt a so-called coating angle 19 with respect to this processing direction 17 of at least 5° to ensure a coating that can have sharp contours.
Furthermore, in a manufacturing method, the surfaces of horizontal parts of the loop radiator to be electrically conductively coated and optionally also the capacitance electrodes can each be disposed in parallel with the reference plane 16 and substantially perpendicular to the processing direction 17. The surfaces to be electrically conductively coated of the substantially vertical radiators can adopt a coating angle 19 with respect to the processing direction 17 of at least 5°, in particular of more than 45°, to ensure a coating having sharp contours.
The shell-shaped protective antenna cover 1a can furthermore have the shape of a stepped pyramid hollowed out from below whose lower side walls lie on the electrically conductive base surface, with the cover having two substantially horizontal part surfaces that are in parallel with this base surface and located above it, that are substantially horizontal, and that are in the form of a first peripheral step, and with the cover having a substantially planar top surface thereabove.
In accordance with the invention, four capacitance electrodes can be located in four respective corners on the lower side of a horizontal part surface of a peripheral step.
The loop 3 can—in an advantageous embodiment of the invention—be located at the lower side of an upper top surface, in particular in the extent of the contour of this top surface.
The four capacitance electrodes 5a, 5b, 5c, 5d can each be connected to a corner of the loop 3 above it via a respective substantially vertical radiator 4, 4a-d.
The protective antenna cover 1a, in particular of shell shape, can be structured in an advantageous embodiment of the invention in the form of a truncated pyramid that is hollowed out from below and that comprises four side walls and a top surface, with these side walls lying on the electrically conductive base surface and with the loop 3 being located at the lower side of the top surface in the extent following the contour of this top surface.
In an advantageous embodiment of the invention, the loop 3 can be respectively connected at each of its four corners to a substantially vertical radiator 4, 4a-d that respectively leads, starting from the respective corner, along the inner edge between side walls contacting the corner until it ends at a spacing 11 from the base surface 6.
The vertical radiators 4, 4a-d, can be respectively connected at a spacing 11 from the base surface to a capacitance electrode 5a, 5b, 5c, 5d that is designed by formation at the respective corner in the form of a horizontal surface that extends at a spacing 11 in parallel with the base surface 6 and that is produced by a gradation of the inner side of the side walls.
The surfaces to be electrically conductively coated can be structured in the form of electrically conductive lattice structures whose mesh is in particular substantially smaller than ⅛ of the wavelength.
The invention will be explained in more detail in the following with reference to embodiments. The associated Figures show in detail:
b) a loop radiator as an electrically conductive coating on the inner surface of a shell-shaped protective antenna cover 1a as in a), but with a view of the inner space from below. The chain dotted line Q describes the view of the cross-section Q. of the arrangement shown in
c) the cross-sectional drawing shows the spacing 11 between the capacitance electrodes 5a, 5b, 5c, 5d and the electrically conductive base surface 6 or the counter-electrode for forming the antenna connector 5e. The observation of the required capacitance values with the aid of the consistency of this spacing 11 is given by the dimensionally stable shape of the protective antenna cover 1a and by its temporal durability. The angle of inclination a of the substantially vertical inner surfaces of the protective antenna cover 1 with respect to the line perpendicular to the conductive base surface 6 can amount to at least 5° and should not fall below the coating angle 19 with a processing direction 17 in parallel with the latter (
b) the representation of the cross-section in accordance with the line Q1 shows the steep side walls of the pyramid that extend, for example, at an angle of less than 90° and greater than 75° to the reference plane 16. In this position, the capacitance electrodes 5b (bottom left) and 5c (bottom right) and the counter-electrodes are shown that are formed by the electrically conductive base surface 6, on the one hand, and by the antenna connector 5e, on the other hand;
c) a representation of the cross-section in accordance with the line Q2 analog to b). The capacitance electrodes are not affected here;
d) a representation of the cross-section in accordance with the line Q3. The vertical radiators 4, 4a-d are inclined at an angle α toward the reference line perpendicular to the base surface 6 that can amount to between 0° and 70°;
e) a representation of the cross-section in accordance with the line Q4; and
f) a representation of the cross-section in accordance with the line Q5;
a) the advantageous combination capability of the terrestrial antennas with a common terrestrial antenna connector 13 at the center of the loop radiator can be seen from the view of the protective antenna cover 1a in
b) shows this arrangement with a view from below from which the combination of the terrestrial reception antenna 14—at whose upper end an end capacitor 16 is formed—with the broadband communication antenna 15 can be seen;
a) a representation of the exemplary design of the cross-section of a protective antenna cover 1a in accordance with the invention (transversely to the direction of travel) with the surfaces electrically conductively coated with strip shaped conductor tracks 12 for the loop radiator and the terrestrial broadband communication antenna 15. These conductor tracks are in particular angled in a V shape in the plane transversely to the direction of travel. It is advantageous for a high quality coating of the protective antenna cover 1a from below from the direction of the perpendicular dashed line not to fall below the coating angle 19 of α=5° between this line and the surface to be coated at any point; and
b) the strip shaped conductor tracks 12 of the terrestrial reception antenna 14 that is higher in comparison with the broadband communication antenna 15 is shown in the representation of a section of the protective antenna cover 1a in accordance with the invention along the direction of travel. These conductor tracks 12 are, in contrast to those of the broadband communication antenna 15, angled in V shape in the plane along the direction of travel. Both antennas meet in the common terrestrial antenna connector point 13.
Advantageous embodiments of the invention are shown again in the following:
Number | Date | Country | Kind |
---|---|---|---|
102016005517.0 | May 2016 | DE | national |
102016010200.4 | Aug 2016 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/060477 | 5/3/2017 | WO | 00 |