EP0353378B1 - Vehicle window antenna - Google Patents

Abstract

The object is to improve a known vehicle window antennae, having a dipole and a conductor running parallel thereto, as a counterweight to the dipole, such that the antennae is shorter, the conductor requires no direct connection to the vehicle bodywork and such that the conductor configuration is relatively simple and can easily be implemented. The solution is for each of the dipole halves (13, 14) to consist of a V-shaped conductor and for the dipole halves, having a geometric length l1 = lambda /4, to be connected to one another at their mutually facing ends, via a straight line piece (17). The conductor (18), running parallel to the longitudinal extent of the dipole (12), is straight and is insulated from the dipole and from the vehicle bodywork. The conductor has a length l4 < lambda /2, where lambda corresponds to the mean operating wavelength. A preferred field of application for the vehicle window antennae is a UHF radio antennae for a radio telephone. <IMAGE>

Description

The invention relates to a vehicle window antenna according to the preamble of claim 1.

State of the art

an ihren freien Enden durch einen Masserückführungsleiter verbunden sind. Der als Gegengewicht wirkende Masserückführungsleiter hat eine dreieck-, rechteck- oder wellenförmige Konfiguration mit einer gestreckten Länge λ und hat auf halber Länge einen Masseanschluß, der üblicherweise mittels eines kurzen Drahtes mit einer in der Fahrzeugkarosserie befestigten Schraube leitend verbunden ist. Die bekannte Fahrzeug-Scheibenantenne ist verhältnismäßig lang, hat eine komplizierte Konfiguration und setzt ein Loch für die Schraube in der Fahrzeugkarosserie voraus.A vehicle window antenna for UHF transmit and receive operation is known (P 37 38 226.8), in which two interconnected loop-shaped antenna conductor sections, each with an elongated length of $\frac{\text{λ}}{\text{2nd}}$

are connected at their free ends by a ground return conductor. The ground return conductor acting as a counterweight has a triangular, rectangular or wave-shaped configuration with an elongated length λ and has a ground connection at half the length, which is usually conductively connected to a screw fastened in the vehicle body by means of a short wire. The known vehicle window antenna is relatively long, has a complicated configuration and requires a hole for the screw in the vehicle body.

task

A vehicle window antenna is known (GB-A-2 180 695), in which two dipole halves are connected to one another at their mutually facing ends via a straight line section and a ground conductor is provided which runs parallel to the longitudinal extension of the dipole. The known vehicle window antenna also requires a conductive connection to the vehicle body in the area of the cable connection.

The invention has for its object to develop a generic vehicle window antenna such that no direct ground connection needs to be made from the ground connection of the counterweight to the vehicle body and that the conductor configuration is relatively simple and easy to implement.

Solution and achievable advantages

This object is achieved in a generic vehicle window antenna by the characterizing features of claim 1.

The advantages that can be achieved with the invention are, in particular, that the conductor acting as a counterweight does not have to be connected directly to the vehicle body and that a simple conductor configuration is created which can be easily installed in or on a vehicle window.

A preferred field of application for the vehicle window antenna according to the invention is a UHF radio antenna for a radio telephone housed in a motor vehicle.

Description of the invention

Fig. 1

eine Fahrzeug-Scheibenantenne in einer ersten Ausführungsform,

Fig. 2

eine Fahrzeug-Scheibenantenne in einer zweiten Ausführungsform,

Fig. 3

eine Fahrzeug-Scheibenantenne in einer dritten Ausführungsform,

Fig. 4

eine Fahrzeug-Scheibenantenne in einer vierten Ausführungsform und

Fig. 5

eine Kraftfahrzeug-Heizscheibe mit einer Fahrzeug-Scheibenantenne nach Fig. 1.

Embodiments of the invention are shown in the drawing using several figures and are described in more detail below. Show it

Fig. 1

a vehicle window antenna in a first embodiment,

Fig. 2

a vehicle window antenna in a second embodiment,

Fig. 3

a vehicle window antenna in a third embodiment,

Fig. 4

a vehicle window antenna in a fourth embodiment and

Fig. 5

a motor vehicle heating disc with a vehicle window antenna according to FIG. 1.

In Fig. 1, 10 denotes a glass pane, that is, for example, the rear window of a motor vehicle. On the inside of the pane 10 or in the inside of the pane there is a vehicle pane antenna 11 made of thin wires or conductor tracks.

, wobei λ der mittleren Betriebswellenlänge entspricht. Die Länge l3 des Leitungsstücks 17 beträgt etwa 0,01 bis 0,015 λ.The vehicle window antenna consists of a dipole 12 with two V-shaped dipole halves 13 and 14, the mutually facing legs 15, 16 of which are conductively connected to one another via a straight line piece 17. The geometric lengths of the two dipole halves 13 and 14 are $$\text{l1 = l2 =}\frac{\text{λ}}{\text{4th}}$$

, where λ corresponds to the mean operating wavelength. The length l3 of the line section 17 is approximately 0.01 to 0.015 λ.

The angle α between adjacent legs of the V-shaped dipole halves 13 and 14 is preferably between 45 ° and 80 °. Depending on the choice of the angle α, the legs belong, for example, to an isosceles, equiangular or right-angled triangle.

hat und der einen Abstand 15 ≈ 0,015 λ von dem Leitungsstück 17 aufweist. Auf halber Länge des Leiters 18 und des Leitungsstücks 17 befindet sich je ein Anschlußpunkt 20 und 21. Der Anschlußpunkt 20 des Leiters 18 ist mit dem Außenleiter 22 und der Anschlußpunkt 21 des Leitungsstücks 17 mit dem Innenleiter 23 eines koaxialen Antennenkabels 24 verbunden, das zum Beispiel einen Wellenwiderstand von 50 Ω hat. Der Leiter 18, der nicht unmittelbar mit der Fahrzeugkarosserie verbunden ist, bildet ein Gegengewicht für den Dipol 12. Die Fahrzeug-Scheibenantenne 11 eignet sich als Funksende- und -empfangsantenne für den VHF- und den UHF-Bereich.A straight conductor 18 is provided parallel to the straight line section 17 and has a length l4 < $\frac{\text{λ}}{\text{2nd}}$

has and a distance 15 ≈ 0.015 λ from the line piece 17. Halfway along the length of the conductor 18 and the line section 17 there is a connection point 20 and 21. The connection point 20 of the line 18 is connected to the outer conductor 22 and the connection point 21 of the line section 17 to the inner conductor 23 of a coaxial antenna cable 24, which for example has a characteristic impedance of 50 Ω. The conductor 18, which is not directly connected to the vehicle body, forms a counterweight for the dipole 12. The vehicle window antenna 11 is suitable as a radio transmission and reception antenna for the VHF and UHF ranges.

The embodiment of a vehicle window antenna 30 according to the invention shown in FIG. 2 has a dipole 31 which corresponds to the dipole 12 in FIG. 1. The conductor 32, which acts as a counterweight, is deviated from the exemplary embodiment according to FIG. 1 in its end regions 33, 34 in such a way that the conductor follows the contours of the dipole 31.

The following is achieved by this special shape of the conductor 32. The greater distance of the dipole 30 from the roof 35 of the vehicle results in a smaller parallel capacity. This is compensated for by dense parallel guidance of the counterweight (conductor 32) on the dipole 31.

λ.FIG. 3 shows a variant of the vehicle antenna according to FIG. 1, in which a dipole 40 is extended compared to the dipole 12 in FIG. 1. 1 each follow another leg 41 and 42, so that new dipole halves 43 and 44 are formed, of which one dipole half 43 is N-shaped and the other dipole half 44 is in the shape of a reverse N has. The angles α shown in FIG. 3 are equal to the angle α in FIG. 1. The geometric length l6 of a dipole half 43, 44 is $\frac{\text{3rd}}{\text{8th}}$

λ.

4 differs from that of FIG. 3 in that the conductor 50 has a configuration which corresponds to that of the conductor 32 in FIG. 2. The same effect is achieved as with a vehicle window antenna according to FIG. 2.

FIG. 5 shows a vehicle window antenna which is used in connection with a vehicle window 60 with a heating conductor arrangement 61. Insulated from the heating conductor arrangement 61, a vehicle window antenna 62 is provided on or in the vehicle window 60, which corresponds to the vehicle window antenna 11 according to FIG. 1. In the vehicle window antenna 62 according to FIG. 1, the heating conductor arrangement 61 is also excited in terms of radio frequency, so that an overall better antenna factor results.

Claims (4)

1. Vehicle window antenna for transmitting or receiving, having a dipole (12) which is fitted in or on the window (10) and whose dipole halves (13, 14) are connected at their mutually facing ends by means of a straight lead piece (17), which dipole halves (13, 14) have a shape deviating from a straight line, and an earth conductor (18; 32), which contains at least one straight piece, and runs parallel to the longitudinal extent of said dipole halves (13, 14), and having an input supply point (21) at half the length of the dipole (12) and having an earth connection (20) at half the length of the conductor (18) for the connection of an antenna cable (24), characterised in that the dipole halves (13, 14) each contain a V-shaped conductor, in that the dipole halves are aligned in mirror-image symmetry with respect to the lateral axis of symmetry of the dipole (12), in that each dipole half (13) has a geometrical length l1 = λ/4, the geometrical length corresponding to the projection of the dipole halves on their longitudinal axis, and in that the earth conductor (18) is insulated from the dipole (12) and the vehicle bodywork, and has a length l4 = < λ/2, where λ corresponds to the mean operating wavelength.
2. Vehicle window antenna according to Claim 1, characterised in that the one dipole half (43) has the shape of an N, and the other dipole half (44) has the shape of an inverted N, and in that each dipole half has a geometrical length, projected onto the longitudinal axis of the dipole halves, of l6 = 3/8 λ.
3. Vehicle window antenna according to Claim 1 or 2, characterised in that the angle (α) between the limbs of each dipole half (13, 14; 43, 44) is between 45° and 85°.
4. Vehicle window antenna according to one of Claims 1 to 3, characterised in that the earth conductor (32) follows the contours of the lead piece (17) and of the limbs (15, 16) of the dipole halves (43, 44) at a distance (15).

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