Window-Integrated Antenna In Vehicles

Abstract

In a window-integrated antenna in vehicles, the heating conductor field is used for FM reception as well as for LMS reception. At least one decoupling element is provided for LMS reception which has a high-frequency, but non-galvanic connection to the heating conductor field. The decoupling element is situated in the heating conductor field, in particular between two adjacent heating conductors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an integrated antenna system for LMS, FM, and possibly TV reception according to the present invention.

FIG. 2 shows another exemplary embodiment including another FM/TV antenna signal decoupling.

FIG. 3 shows a comparison of the reception level in the LMS frequency range.

DETAILED DESCRIPTION

FIG. 1 shows a window-integrated antenna made up of heating conductors 3, running parallel to one another, which each meet a busbar 4 at their left and right ends. The heating conductor field formed in this way is supplied with heating current via an FM/TV choke 5 in the supply leads (Ub heating). Depending on the acceptance of the basic noise, an AM blocking circuit 13 having more or less expensive filters is or is not provided. Antenna connection point 1 for FM/TV and LMS signals is galvanically linked with a decoupling element 5 in the heating conductor field but not with the heating conductor field. Decoupling element 6 may be designed as a straight-line conductor, as an open conductor loop as shown in FIG. 1, or as a closed conductor loop, or a combination of the latter elements. A structure as long as possible is advantageous. Decoupling element 6 is situated in particular between two adjacent heating conductors 3 and runs parallel (legs of the open conductor loop) to the entire length of both heating conductors 3. The distance of decoupling element 6 or its conductor segments parallel to heating conductors 3 should be as small as possible, in order to ensure a capacitive coupling for FM/TV frequencies. Grounding point 9 for the connection of active antenna module 7 is advantageously located in the direct proximity of antenna connection point 1 in the right upper corner of the heating conductor field on metallic frame 8 surrounding the window (shown in a dashed line).

The heating conductor structure of the window is designed in such a way that a resonant structure for FM frequencies is created at antenna connection point 1, e.g., via additional vertical crossing lines 10 which are galvanically connected to the parallel heating conductors at each crossing point and are situated on the equi-potential points formed by the voltage distribution.

The decoupled antenna signals are separately amplified (AM, FM, TV1) in electronics module 7 and, if needed, filtered and supplied to TV tuner 11 or radio 12.

FIG. 2 shows another exemplary embodiment in which another FM/TV antenna signal decoupling is formed from antenna connection point 2, galvanically linked to the heating field on the opposite side, and a close-by ground terminal, thereby forming a dual-antenna system. Additional antennas may be formed from the heating field at another location, e.g., two additional antennas to generate a quadruple-antenna system. This makes it possible to scan a further FM or TV range, to operate a second FM receiver, or a diversity effect due to different reception signals at the two antenna connection points 1 and 2 may be utilized, such as the one which may occur under unfavorable reception conditions during mobile use.

A further advantage of the present invention becomes apparent at this point:

The capacitance of the antenna conductor vis-á-vis the chassis ground is a deciding factor in LMS reception. In the system according to the related art, the overall capacitance of the system with regard to antenna connection 1 is increased in a dual-antenna system by connecting a second electronic module having a certain input capacitance. In other words, part of the received LMS signal is diverted toward ground via the second module, thereby impairing the overall reception. This circumstance is prevented in the antenna system according to the present invention.

Measurements show that the reception of LMS signals using the system according to the present invention shown in FIG. 1 is comparable to a system in which the antenna connection point is galvanically linked with the heating field at the upper outer corner. It becomes apparent here that an open conductor loop, as shown in FIG. 1, yields the best results. The reception level is marginally lower, but a lower basic noise is generated by the heating current in exchange.

The reception performance for FM/TV reception is comparable to known systems.

Claims

1-9. (canceled)

10. A window-integrated antenna in a vehicle, comprising: a heating conductor field provided for at least one of FM reception, TV reception, and LMS reception; andat least one decoupling element for at least the LMS reception, the at least one decoupling element including a high-frequency and non-galvanic connection to the heating conductor field, wherein the at least one decoupling element is situated in the heating conductor field between two adjacent heating conductors.

11. The window-integrated antenna as recited in claim 10, wherein the at least one decoupling element is for the FM reception and the TV reception.

12. The window-integrated antenna as recited in claim 11, further comprising: an FM/TV choke provided in a heating circuit.

13. The window-integrated antenna as recited in claim 10, further comprising: antenna conductors situated in the heating conductor field substantially perpendicularly to the heating conductors and galvanically linked to the heating conductors.

14. The window-integrated antenna as recited in claim 13, wherein: the antenna conductors are designed, with regard to at least one of a length and a position thereof, in such a way that a resonance-like behavior of the antenna occurs at a connection end of the at least one decoupling element in an FM range.

15. The window-integrated antenna as recited in claim 10, wherein the at least one decoupling element includes at least one of a straight-line conductor, an open conductor loop, and a closed conductor loop.

16. The window-integrated antenna as recited in claim 10, wherein a grounding point for decoupling at least one of an LMS antenna signal, an FM antenna signal, and a TV antenna signal is located in a proximity of a connection end of the at least one decoupling element.

17. The window-integrated antenna as recited in claim 10, wherein at least one further FM/TV antenna signal decoupling is provided that is galvanically linked to the heating conductor field, and to a busbar situated at a distance from a connection end of the at least one decoupling element.

18. The window-integrated antenna as recited in claim 10, wherein a distance of the at least one decoupling element to one of the heating conductors is selected to be so close that a capacitive coupling with the heating conductor is ensured for FM/TV frequencies.

19. The window-integrated antenna as recited in claim 18, wherein the at least one decoupling element includes one of a straight-line conductor and a conductor loop.