EP1575125A1 - Usage of an inverted-L antenna in a motor vehicle - Google Patents

Abstract

The inverted L-shaped antenna for use in a vehicle is electromagnetically connected to a magnetic strip conductor in a non-contact manner. The antenna (1,5) is affixed in the region of a flat part (4) of the vehicle made of an electromagnetically transparent material. This flat part is a part of the outer body of the vehicle. The antenna is located underneath this flat part and is independent from it as far as manufacturing technology is concerned.

Description

The invention relates to the use of an inverted L-antenna in a motor vehicle according to the preamble of the claim 1.

Such uses are already known (JP-A-2001-189616), where antennas in multi-layer glass panes embedded by individual glass layers as Dielelektrikum be used between the L-shaped or F-shaped Part of the antenna and the microstrip line. Thereby are the L-shaped or F-shaped parts contactless, electromagnetically coupled to the microstrip line.

Inverted L-antennas are known for example from DE 198 80 497 Tl, EP 856 907 A1 and EP 1 024 552 A2. Further references are: R. King et al., Transmissicnline missile antennas, IRE Trans. Antennas Propagat., vol. 8th, pp. 88-90, January 1960; R.J.F.Gürtler: Isotropic transmission-line ailtenna and its toroid-pattern modification, IEEE Trans. Antennas Propagate, vol. 25, pp. 386-392, May 1977; M.J. Ahmann et al., A novel hybrid inverted L-antenna with wide bandwidth, 12th IEE International Conference Antennas & Propagat. 2003, Vol (2) pp. 720-722; K. Kagoshima et al., Analysis of a planar inverted F-antenna fed by electromagnetic coupling, 1992 IEEE Int. Antenna's propaganda. Symp. Di. vol. 30, pp. 1702-1705, July 1992; K. Virga and Y. Rahmat-Samii, An enhanced-bandwidth integrated dual L antenna for mobile communications systems - Design and measurement, 1995 IEEE Int. Antenna's propaganda. Symp. Dig. vol. 33, pp. 1120-1123, June 1995.

Furthermore, it is known in motor vehicles abutment antennas to mount on glass or plastic roofs of vehicles.

The present invention is based on the object, a To propose an antenna for a motor vehicle that is easy to assemble is and has good reception properties.

This object is according to the present invention as claimed 1 solved, after which the inverted L antenna in the range a flat part of the motor vehicle from an electromagnetic transparent material is attached, the planar part of the outer skin of the motor vehicle is, with the inverted L antenna below this flat part is, wherein the L-antenna manufacturing technology regardless of the part mentioned.

The electromagnetically transparent part can, for example a roof made of glass or plastic (ddf, also a sunroof), or a boot lid made of plastic. As well The windows of the vehicle can do this electromagnetically represent transparent part.

By the flat part of the outer skin of the motor vehicle and the antenna is integrated under the vehicle skin is, there is a design advantage, because no antenna part out of the silhouette of the outer skin of the vehicle protrudes. Further advantages arise with regard to the installation space as well as the robustness of the antenna. This is especially true in the With regard to vandalism damage.

Since the antenna manufacturing technology independent of this area Part is advantageous, the production is simplified. Compared to the prior art, it is therefore not necessary already during the production of the corresponding Part to integrate the antenna. Leave the individual parts this advantageous separately and independently make and deliver to the band for production of the vehicle.

The radiating element of the antenna according to the invention is a Inverted L-antenna, like these in principle from the literature is known. The inverted L-antenna can be bent X / 4 monopoly on ground plane or in its planar Shape, which has a larger bandwidth than Kurzschlussverkürzte Microstrip line antenna are considered.

It belongs to the resonant antennas and the wavelength of the Here interesting basic mode is then - analogous to λ / 4 monopole - about four times the total length of the L-shaped Part. While the length is the resonant frequency of the Antenna determines have height (the kink) and width of the L-shaped parts affect the bandwidth of the antenna. With increasing width of the L-shaped part increases the bandwidth the antenna, but the width below the emergence of transverse resonances in the frequency bands of interest should stay. Your radiation diagram is roughly equivalent that of a λ / 4 monopole on mass area and the most widespread planar inverted F-antenna, which is an extension represents the L-antenna. With increasing width of the planar Antennas loses the directional diagram of its omnidirectional, monopoly-like character. It must therefore be a compromise between bandwidth and directional diagram are found.

The lower construction heights compared to the λ / 4 monopole (kinking, increased final capacity) make inverted L and F - Antenna with similar radiation characteristic too well suited Radiator elements, if it - with a horizontal ground plane - a possibly omnidirectional, vertically polarized Radiation and / or reception in azimuthal level goes, like this demanded especially in mobile radio antennas in the automotive sector is.

In the embodiment according to claim 2, the height of the microstrip line less than half the height of the L-shaped Antenna.

Is the height of the coupling microstrip line, for example 0.3 times to 0.5 times the antenna height advantageous that the radiation properties in horizontal In any case, the direction is at least slightly influenced.

In the embodiment according to claim 3, at least one another L-antenna laterally coupled to the microstrip line.

In this embodiment, there is an advantage over one another embodiment, namely the capacitive coupling in the form of a coaxial fed coupling plate with additional parallel load. For in such an embodiment, it is namely not easily possible to couple more antennas.

It can be so by the embodiment of the present Invention in a simple way reception facilities in realize different frequency bands by different L-shaped antennas coupled to the microstrip line become.

This coupling differs from multiband antennas, the on several radiation-coupled single band antennas (often L or F antennas) or complex geometries (folded, slotted, ...) with several resonances.

In the embodiment according to claim 4, the parts of Antenna in the production of the body with punched and shaped accordingly.

This advantageously results in a simplified production the antenna in the manufacturing process. Furthermore, by the Use of vehicle parts as antenna weight and installation space saved up.

In the embodiment according to claim 4, the microstrip line bent at its end 90 degrees down, where a gap between the end of the vertical part of the microstrip line and the horizontal ground plane remains, the horizontal ground plane continues to be an additional one vertical element, which is at least substantially arranged parallel to the vertical part of the microstrip line is, wherein further the inner conductor of the coaxial cable is contacted with the microstrip line, and wherein the Outer conductor of the coaxial cable at the additional vertical element will be contacted.

An advantage of this design are the reduction and partial compensation of the inductive component, resulting in a broadband good adaptation and low insertion loss leads. By the vertical ground surface can be the inductive acting through the Inner conductor to be bridged gap to be kept small. Of further is the inductive effect of the inner conductor by the capacitive effect of the two parallel metal surfaces partially compensated by vertical microstrip line and ground plane.

In the embodiment according to claim 6, there is the area Part of glass or plastic and used as antenna radome.

The electrical permittivity results in a shortening of the resonant antenna elements, which are then used in the design the antennas must be considered.

In the embodiment according to claim 7 are the horizontal Elements of the L-antenna directly on the inside of the glass or plastic existing flat part.

As a result, the radiator elements of the antenna can be shortened maximum because of the electrical permittivity of the glass or plastic.

In the embodiment according to claim 8, the horizontal Elements of the L antenna a certain distance to the plane Part up.

In this embodiment, a greater independence results to tolerants, for example, from the Thickness or the permittivity of the glass can result. Advantageous the given distance is kept small.

In the embodiment according to claim 9, the L-antenna for Microstrip line laterally offset at the front of the Microstrip line arranged.

Due to this lateral offset in connection with the gap distance the open end of the microstrip line to vertical part of the L-antenna can be an adaptation of the coupling be made.

In the embodiment according to claim 10, at least one L-antenna arranged laterally to the microstrip line.

Advantageously, this results in an easy way by different resonance frequencies a multi-band antenna to realize.

Fig. 1

die berührungalose, kapazitive Ankopplung einer L-förmigen Antennenstruktur an die Mikrostreifenleitung,

Fig. 2

eine Seitenansicht einer L-förmigen Antennenstruktur mit einer Mikrostreifenleitung unter einer dielektrischen Abdeckplatte,

Fig. 3

die Ankopplung weiterer Antennen an die mikrostreifenleitung und

Fig. 4

die Kontaktierung einer Koaxialleitung.

Showing:

Fig. 1

the contact-ionic, capacitive coupling of an L-shaped antenna structure to the microstrip line,

Fig. 2

a side view of an L-shaped antenna structure with a microstrip line under a dielectric cover plate,

Fig. 3

the coupling of other antennas to the microstrip line and

Fig. 4

the contacting of a coaxial line.

In contrast to some other inverted L antennas described For example, the present antenna element will not be coaxial fed at its base or at a higher point, but is non-contact, electromagnetic (capacitive) coupled to a microstrip line 2, as shown in FIG Figure 1 is shown. In contrast to the coaxial feed is the L-shaped antenna structure 1 here without gap conductive connected to the ground plane 3. The structure is simplified considerably.

This type of power supply is one of the standard coupling options in microstrip antennas already known.

The height of the coupling microstrip line 2 is here significantly less than the height of the L-shaped steel element 1, e.g. 0.3 times to 0.5 times the antenna height the radiation properties in the horizontal direction as possible little to influence.

The line impedance of the microstrip line 2 may be relative be selected freely, with the connection to z. B. a 50 Ω coaxial system, a 50 Ω line for power supply.

A loose binding of the field to the microstrip line 2, due to a dielectric low Permittivät, reinforced the coupling of line 2 and antenna element. 1 Due to a low-loss dielectric, the dielectric Losses on the microstrip line 2 can be reduced. Optimal with respect to both requirements, air is a dielectric, which e.g. by hard foam or low-loss, low-permeability Supports or spacers along the line 2 can be approximated.

The coupling of the L-antenna 1 can either in shown Way frontally at the end of an open-end microstrip line 2 or laterally done. For a coupled Antenna 1 or the first element 1 of a multi-band antenna arrangement is the frontal coupling advantageous. In this case forms the open end of the microstrip line 2 a narrow gap to the vertical part of the L-antenna 1, which can be seen in the illustration of Figure 2. With gap width and lateral offset of the L-antenna 1 to Line 2, the adaptation can be optimized. The radiant Element 1 - the L antenna - comes with appropriate mechanical Texture and attachment of the foot edge on the Ground surface 3 without dielectric or mechanical supports made. Through the use of dielectrics or ferrites can in Advantageously, the L-shaped part 1 are reduced in size. In particular, when installed under a glass or plastic roof or a plastic tailgate 4 the anyway existing dielectric layer (glass or plastic) - like it is shown in Figure 2 by the reference numeral 4 - above the L-antennas 1 as a radome and the antenna length shortening Dielectric be used. The dielectric layer but forms only part of the cover of the antenna 1 and in particular is not located between the L-shaped Part 1 and the microstrip line 2.

Particularly advantageous on the L antenna 1 with electromagnetic Coupling via microstrip line 2 is the fact that to a microstrip line 2 with little effort more L-antennas 5 as resonant radiator elements without contact can be coupled. If these elements 5 different Have resonant frequencies can be on this simple way to create multiband antennas.

The coupling of the first L-antenna 1 is carried out as described frontally, the other antennas 5 takes place side of the microstrip line 2, as shown in the illustration Figure 3 is shown. Figure 3 shows only one more Antenna 5 for a lower frequency band, but it is possible to attach several other antennas 5.

For a good coupling of the antenna 5, the positioning takes place the side antennas 5 in such a way that the open End of the L antenna 5, at which the electric field maximum is about the edge of the microstrip line 2 in the amount of an electric field maximum (at the resonant frequency the laterally-coupled antenna) on the microstrip line 2 is located. The electric field maximum at End of the line 2 feeds the frontal antenna 1, the second maximum can then be used for side antennas 5 become.

An advantageous distance of the L-antennas 1, 5 is therefore in about half a wavelength of the cable from the end of the line 2. If this distance should be reduced, it is possible through a line dielectric in the area between the both antennas 1, 5, the line wavelength and thus the to shorten the minimum distance.

The standing waves on the line 2, which are the desired Field maxima in the frequency bands of the lateral antennas 5 generate, arise outside the frequency band of the frontal Antenna 1 due to reflections on this antenna (mismatch) ,

A coupling of the other antennas 5 is on both sides the microstrip line 2 possible, so that in adjacent Frequency bands no space conflict arises. Due to the Distance between the individual antennas 5 is the mutual shading the antenna elements relatively low, so that a received almost omnidirectional radiation characteristics remains. Due to the flat, low design of this antenna arrangement It is especially suitable for the externally invisible Integration under glass or plastic roofs or rear cover 4 of motor vehicles.

Figure 3 shows such an antenna system. The electrically transparent Glass or plastic 4 can be in an advantageous Way can be used as an antenna radome and causes due to its electrical permittivity also a shortening of the resonant antenna elements used in the design of the antennas however, it must be taken into account.

The horizontal elements of the L-antennas 1, 5 can thereby directly on the inside of the glass or of the plastic 4 lie or are in close proximity to it. Of the Advantage of the first case lies in a maximum shortening the radiator elements 1, 5 by the electrical permittivity of the glass or plastic during the second case (lateral view corresponding to the representation of FIG. 2) is less sensitive to tolerances due to the distance for example, the thickness and permittivity of the glass / plastic 4, thickness variations of the distance antenna 1, 5 - glass / plastic 4 can affect.

Furthermore, advantageously, the inverted L-antennas 1, 5 and the vertical element 6 of the ground plane. 3 as sheet metal parts z. B. the roof frame are executed, wherein in this case, the horizontal ground plane 3 through the roof frame is formed. The parts can z. B. by a forming and punching process are produced and under the Roof construction to be applied to the roof frame. Parts of Antennas are thus formed by the vehicle body.

In a final step then still has the microstrip line 2, e.g. with pre-assembled inner conductor of the coaxial cable 7 are introduced and the outer conductor of the coaxial cable 7 are connected to the vertical ground surface 6.

This use of original or modified dielectric and metallic vehicle parts as functional elements The antenna reduces weight, saves manufacturing and Assembly costs.

1. Das Ende der Mikrostreifenleitung 2 ist um 90 Grad nach unten gebogen, wobei ein Spalt 8 zwischen dem Ende des vertikalen Teils der Mikrostreifenleitung 2 und der horizontalen Massefläche (hier nicht gezeigt) bleibt.

2. Die horizontale Massefläche besitzt ein zusätzliches vertikales Element 6, welches parallel zum vertikalen Teil der Mikrostreifenleitung 2 in geringem Abstand angeordnet ist. Höhe und Breite des vertikalen Elements 6 entsprechen dabei in vorteilhafter Ausprägung Höhe und Breite der Mikrostreifenleitung 2.

3. Die Mikrostreifenleitung 2 wird mittig vom Innenleiter 9 des Koaxialkabels in gezeigter Weise hinter der Biegekante im horizontalen Teil der Mikrostreifenleitung 2 kontaktiert.

4. Der Aussenleiter (Schirm) 10 des Koaxialleiters 7 kontaktiert die Massefläche am zusätzlichen vertikalen Element 6 der Massefläche. Diese vertikale Element 6 weist vorteilhaft eine Aufnahme für das Koaxialkabel 7 auf.

5. Das Koaxialdielektrikum 11 kann im Bereich des Spaltes zwischen dem zusätzlichen vertikalen Element 6 und dem senkrechten Teil der Mikrostreifenleitung 2 stehen bleiben oder entfernt werden.

The transition of the coaxial line 7 usually used for connecting antennas on the feeding microstrip line 2 can be done in many ways. FIG. 4 shows a variant which is particularly advantageous for this structure:

1. The end of the microstrip line 2 is bent down 90 degrees, leaving a gap 8 between the end of the vertical part of the microstrip line 2 and the horizontal ground plane (not shown here).

2. The horizontal ground plane has an additional vertical element 6, which is arranged parallel to the vertical part of the microstrip line 2 at a small distance. Height and width of the vertical element 6 correspond to the height and width of the microstrip line 2 in an advantageous embodiment.

3. The microstrip line 2 is centrally contacted by the inner conductor 9 of the coaxial cable in the manner shown behind the bending edge in the horizontal part of the microstrip line 2.

4. The outer conductor (screen) 10 of the coaxial conductor 7 contacts the ground surface on the additional vertical element 6 of the ground plane. This vertical element 6 advantageously has a receptacle for the coaxial cable 7.

5. The coaxial dielectric 11 may remain or be removed in the region of the gap between the additional vertical element 6 and the vertical part of the microstrip line 2.

An advantage of this design are the reduction and partial compensation of the inductive component, resulting in a broadband good adaptation and low insertion loss leads. By the vertical ground surface 6, the by the inductively acting Inner conductor 9 to be bridged gap to be kept small. Furthermore, the inductive effect of the inner conductor 9 by the capacitive effect of the two parallel metal surfaces of vertical microstrip line 2 and ground plane 6 partially compensated.

In the special case of a 50 Ω system with air (spacer made of rigid foam) as a dielectric results following geometry: height of the microstrip line 2 over horizontal Ground area: 5 mm, width of microstrip line 2: 23 mm, gap width between vertical piece of microstrip line 2 and vertical ground surface 6: 2 mm, gap width between the end of the vertical piece of the microstrip line 2 and horizontal ground area: 2 mm. The microstrip line 2 can of course also be used on other high frequency realized low-loss substrates (substrates) become.

Claims (10)

Use of an inverted L-antenna (1, 5) in a motor vehicle, which is non-contact, electromagnetically coupled to a microstrip line (2),
characterized in that the inverted L-antenna (1, 5) in the region of a flat part (4) of the motor vehicle from an electromagnetically transparent material is attached, wherein the planar part (4) is part of the outer skin of the motor vehicle, wherein the inverted L-antenna is below this planar part (4), wherein the L-antenna (1, 5) manufacturing technology independent of said part (4). Use of an inverted L-antenna according to claim 1,
characterized in that the height of the microstrip line (2) is less than half the height of the L-shaped antenna (1, 5). Use of an inverted L-antenna according to one of the preceding claims,
characterized in that at least one further L-antenna (5) is coupled laterally to the microstrip line (2). Use of an inverted L-antenna according to one of the preceding claims,
characterized in that the parts of the antenna (1, 5) are punched in the production of the body with and shaped accordingly. Use of an inverted L-antenna according to one of the preceding claims,
characterized in that the microstrip line (2) is bent downwards at its end by 90 degrees, leaving a gap between the end of the vertical part of the microstrip line (2) and the horizontal ground plane (3), that the horizontal ground plane (3) an additional vertical element (6), which is arranged at least substantially parallel to the vertical part of the microstrip line (2), that the inner conductor (9) of the coaxial cable (7) with the microstrip line (2) is contacted, and that the outer conductor ( 10) of the coaxial cable (7) is contacted on the additional vertical element (6). Use of an inverted L-antenna according to one of the preceding claims,
characterized in that the flat part (4) consists of glass or plastic and is used as Antennenradom. Use of an inverted L-antenna according to one of the preceding claims,
characterized in that the horizontal elements of the L-antenna lie directly on the inside of the glass or plastic existing flat part (4). Use of an inverted L-antenna according to one of claims 1 to 6,
characterized in that the horizontal elements of the L-antenna have a certain distance from the flat part (4). Use of an inverted L-antenna according to one of the preceding claims,
characterized in that the L-antenna (1) to the microstrip line (2) is offset laterally on the end face of the microstrip line (2) is arranged. Use of an inverted L-antenna according to one of the preceding claims,
characterized in that at least one L-antenna (5) is arranged laterally to the microstrip line (2).

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