DE202007000962U1 - Miniature antenna for a roof rack of a motor vehicle - Google Patents

Abstract

Antenna system for a motor vehicle, comprising:
at least one roof rack constructed to be installed on a motor vehicle, the roof rack including an enclosed inner surface and a ground connection for connecting an antenna element to the ground of the motor vehicle, and
an antenna element held by the enclosed inner surface of the roof rack and electrically coupled to the ground connection.

Description

Task of invention

The This invention relates generally to a car radio miniature antenna with printed circuit board, preferably for AM / FM signal reception, the antenna being arranged in a roof rack of an automobile is.

background the invention

conventional Car antennas can damage in consequence of their length suffer when the automobile is in a car wash or at the garage door is why a need after a compact antenna solution they are less likely to be damaged or damaged is stolen.

Some Documents relating to this technical field are:

• [1] H.A. Wheeler, "Fundamental Limits of Small Antennas" (Basic Limits small antennae), Proceedings of The I.R.E (IEEE), December 1947, Pages 1479-1484.
• [2] James S. McLean, "A Re-Examination of the Fundamental Limits on Radiation Q of Electrically small antennas "(review of basic limits of radiation Q of electrically small antennas), IEEE Transactions on Antennas and Propagation, Vol. 44, No. 5, May 1996, pages 672-675.

Description of the invention

The The present invention relates to accomplishing the arrangement of a Radio antenna in difficult, physical conditions, such as e.g. with vibration or moisture.

• – Implementation der gedruckten AM/FM-Antenne in einem robusten, elektrischen Substrat oder einem dielektrischen Träger, um die richtige Position und Brauchbarkeit der unterschiedlichen metallischen Teile der Antenne sicherstellen zu können.
• – Das aktive AM/FM-Funksystem kann in einer entfernten Position mit einer speziellen Verbindung mit der Erde des Automobils oder an dem gleichen physikalischen Träger der Antenne mit Verbindungen zu der Automobilerde angeordnet werden.
• – Das Dachgepäckträger-Kunststoffteil muss einen wasserdichten Schutz der Antennenleiterplatte und der aktiven Systemkomponenten, der Befestigung und der Position der Antenne im Automobil sicherstellen.
• – Das Vermögen, weitere Antennendienste in dem gleichen Raum zu integrieren.

This task is solved by the following technical features:

• Implementation of the printed AM / FM antenna in a robust, electrical substrate or dielectric support to ensure the correct position and usability of the different metallic parts of the antenna.
• The active AM / FM radio system can be placed in a remote position with a special connection to the ground of the automobile or on the same physical support of the antenna with connections to the automotive earth.
• - The roof rack plastic part must ensure a watertight protection of the antenna board and the active system components, the mounting and the position of the antenna in the car.
• - The ability to integrate additional antenna services in the same room.

More accurate comprises the antenna system according to the present invention Invention a roof rack, the is constructed such that it is installed on a motor vehicle can be, with the roof rack a enclosed or encapsulated inner surface and a ground connection contains which is constructed such that an antenna element having an earth potential is electrically connected to the motor vehicle. The antenna system further comprises an antenna element attached to the trapped, inner surface the roof rack mounted is and is electrically coupled to the ground connection.

These Antenna can be grouped with other antennas for wireless connections be or could one Be part of a group with more than one antenna to receive the signal to be able to improve. It is also possible, an over-hollow detector with a reversing camera add, to avoid a blind spot.

The Arranging a miniature radio antenna or a miniature radio antenna in an outer position of the Automobile, e.g. the roof rack position, is for many reasons beneficial: to the aesthetic Impression of the vehicle to improve the interference or interference Avoid automotive electronics to avoid typical damage to avoid the conventional Automobile antennas may suffer as a consequence of their length, if the automobile is in a car wash or in a garage door, and finally a better, compact antenna solution with less possibility to be stolen.

description the drawings

In order to complete the description and to provide a better understanding of the invention, a set of drawings is provided. These drawings form an integral part of the specification and illustrate a preferred embodiment of the invention, which should not be interpreted as limiting the scope of the invention, but only as an example of how the invention may be practiced. The drawings have the following figures:

1 is a side view of a roof rack plastic carrier for a motor vehicle;

2 is a schematic representation of the antenna system, which is installed in the roof rack;

3 (a) is an example of the location of the miniature FM / AM antenna on the roof of the automobile in the roof rack plastic carrier. 3 (b) is a detail that matters 3 (a) is taken.

4 is an example of the antenna installation on the roof rack plastic carrier and with its ground point connection;

5 (a) shows the position of two combined AM / FM subminiature antennas on both sides of the roof rack; 5 (b) is a schematic representation of the combined antenna system;

6 shows a block diagram of an antenna connection unit.

7 is another block diagram of the antenna connection unit;

8th shows examples of space filling curves;

9 shows an example of a space filling curve;

10 shows a space filling curve within a first grid;

11 shows a space-filling curve within a second grid;

12 shows a space filling curve within a third grid;

13 shows a space filling curve within a first cell counting grid; and

14 shows a space-filling curve within a second cell count grid.

detailed Description of the preferred embodiment

2 shows an antenna system according to the invention, in which an antenna element ( 1 ) formed as a space filling curve on a surface of a substrate ( 2 ), eg on a printed circuit board. An active AM / FM module ( 3 ) is connected to the antenna element ( 1 ) by means of a wire connection ( 4 ) connected. An output coaxial cable ( 5 ) and a ground point connection ( 6 ) are also compatible with the active module ( 3 ) connected.

The robust, electrical substrate ( 2 ) or the dielectric support ensures the correct position and usability of the different metal parts of the antenna.

A space filling curve or a lattice dimension curve is considered as a concept for the design of the antenna element (FIG. 1 ) used. The antenna geometry may be interpreted on the basis of a Hilbert curve as in FIG 2 is shown, or at least contain a curve with a cell count or grid size greater than 1.5. In general, the higher the cell count size or grid size, the higher the antenna size reduction. In some cases, an antenna containing a curve with a dimension greater than 1.9 is preferred. The space fill curve or grid dimension curve is optimized for FM / Am reception.

A coaxial wire or a single wire is used for the wire antenna connection ( 4 ) is used to provide a perfect electrical connection between the antenna element and its active module ( 3 ), when the active module is removed from the antenna element ( 1 ) is arranged.

The active AM / FM module ( 3 ) consists of a PCB (Printed Circuit Board) with SMD components of FM and AM amplifier stages. The printed circuit board is implemented in an amplifier with a robust and inexpensive substrate on the same printed circuit board or PCB with the space fill curve geometry. It can also be found in other cases that these two elements are in the same PCB.

The antenna system of the present invention may be used in the roof rack plastic carrier incorporated in the roof rack 1 is shown, which in turn may be mounted on an automobile in the positions shown in Figs 3 . 4 and 5 are shown.

The roof rack is provided with an inner surface, and the antenna element is preferably held by the inner surface such that the antenna element is housed within the roof rack to support the antenna element (10). 1 ) to protect against moisture or external damage.

The AM / FM miniature antenna device of the present invention may advantageously be attached to the roof of the vehicle adjacent to the rear window glass (FIG. 13 ) with the earth connection ( 6 ) are arranged on the edge of the automobile rear frame, as in 3 and 5 is shown.

one the advantages of the antenna on the roof rack is its integrated solution. It There is no additional costs for the automaker as a result of having the antenna of one Supplier of the roof rack comes, why the automotive manufacturer only suspects the plastic carrier execution a bore and the other, can install important works, the otherwise for the installation of a mast in an automobile are required.

One Another advantage that is very important is the aesthetic solution. With this solution will be the picture of a big one Avoided that sticks out of the automotive mold. This Characteristic is for the vehicles of the future very interesting.

One Another important advantage of this antenna design is that that possibility it is avoided that the antenna is stolen or in the normal Use stolen when cleaning the car or at the parking locations is or breaks off, where the roof is sometimes not high enough.

It it has been found that an electrically small antenna, which is contained within a given volume, an inherent one Minimum value of Q [2]. This represents a limitation of achievable Impedanzbandbreite an electrically small antenna dar. Of a Miniature antenna in an FM band, where λ is larger than other wireless Services such as GSM900, GSM1800, GPS is in the same volume expects a very small impedance bandwidth to be obtained why a way to solve This problem can be achieved by using two miniature antennas be combined with an appropriate separation between them.

Examples of this application with two combined FM / AM miniature antennas are in 5 and 7 shown.

The combined system includes two FM / AM miniature antennas ( 9 . 9 ' ) combined.

• a) ein robustes, elektrisches Substrat oder einen dielektrischen Träger, um die richtige Position und Brauchbarkeit der unterschiedlichen Metallteile der Antenne sicherstellen zu können.
• b) eine Raumfüllkurve oder eine Gitterabmessungskurve als ein Konzept der Antennenauslegung bzw. des Antennenaufbaus. Die Antennengeometrie enthält einen Aufbau auf der Basis einer Hilbert-Kurve oder zumindest eine Kurve mit einer Zellzählungsabmessung oder einer Gitterabmessung größer als 1,5. Im allgemeinen wird die Zellzählungsabmessung oder die Gitterabmessung um so höher je höher die Antennengrößenverdichtung ist. In einigen Fällen wird eine Antenne, die eine Kurve mit einer Abmessung größer als 1,9 enthält, bevorzugt. Die Raumfüllabmessung oder Gitterabmessungskurve ist für den FM/AM-Empfang optimiert.

Two radiating elements, as described in the previous sections, have:

• a) a robust, electrical substrate or a dielectric support in order to ensure the correct position and usability of the different metal parts of the antenna can.
• b) a space fill curve or a lattice dimension curve as a concept of antenna design. The antenna geometry includes a Hilbert curve based configuration or at least one curve with a cell count dimension or grid size greater than 1.5. In general, the higher the antenna size compression the higher the cell count size or grid size. In some cases, an antenna containing a curve with a dimension greater than 1.9 is preferred. The space fill or grid dimension curve is optimized for FM / AM reception.

The two FM / AM miniature antennas ( 9 . 9 ' ) are each with voting units ( 10 . 10 ' ) to ensure that the two miniature antennas work perfectly in the FM / AM bands. These units may contain coils or capacitors to optimize the entire system for FM / AM reception. This tuning unit must be implemented in or on a robust electrical substrate or in a dielectric substrate in order to be able to ensure a correct position and usability of the different components of the tuning antenna unit.

Two RF coaxial cables ( 11 . 11 ' ) with the lengths L1 and L2 connect the two tuning antenna units ( 10 . 10 ' ) with the antenna connection unit ( 12 ). These coaxial cables may be designed to operate at 50Ω or 75Ω depending on the input impedance of the radio.

The antenna connection unit ( 12 ) includes a perfect 50 Ω matched unit to ensure correct addition of the two complex signals coming from the two antennas. There are different ways for the realization of this unit. One of these is to use a component constructed by mini-circuits (mini-circuits) el TCP-2-10, which has an adaptation section ( 14 ) and a divider ( 15 ), as in 6 is shown.

If required at the output of the combined antenna system, an active module ( 3 ' ) to amplify the signal values.

The active module ( 3 ) has a PCB (printed circuit board) with SMD components of FM / AM amplifier stages in the same states as described in the previous paragraphs. PCB (printed circuit board) with SMD components of the FM and AM amplifier stages. The circuit board is mounted in an amplifier with a rugged and inexpensive substrate on the same PCB of the antenna connection unit.

It is possible, too, the roof rack one Add camera, to increase the visibility to the rear and to avoid a blind spot.

In a preferred embodiment of the invention, the antenna element ( 1 ) is a multi-band antenna and is adapted to transmit and / or receive signals for multiple communication services. For example, the multi-band behavior may be obtained by an antenna element having sections formed as a space fill curve having a different cell count dimension or grid dimension, such as in the embodiment of FIG 2 is shown.

The main communication services covered by the antenna system of the invention are:
Broadcast radio reception in AM (LW: 150 kHz-279 kHz and MW: 530 kHz-1710 kHz) and in Japanese and European FM band (78 MHz-108 MHz).

Further Services included in the device may e.g. GSM900, GSM1800, GPS, DAB, TV, DVB, DTB, PCS1900, KPCS, CDMA, WCDMA, TDMA, UMTS, TACS, ETACS, SDARS, WiFi, WiMAX, UWB, Bluetooth, ZigBee, TV, DVB.

principle the space filling curves

8th shows examples of space filling curves. The space filling curves 1501 to 1504 Examples of space filling curves for prior art antenna designs.

The Raumfüllkurven to fill the surface or the volume where they are arranged, in an efficient manner out while their linear curve properties are maintained.

Next other possible Definitions could a space filling curve be defined as a non-periodic curve, which is defined by a Number of connected, straight segments is composed, the is less than a part of the working free space wavelength, wherein the segments are arranged so that none of the adjacent and connected segments forms another, longer, straight segment and wherein none of these segments intersects another.

9 to 11 show an example of how the grid dimension is calculated.

The grid dimension of the curve (cf. 10 ) can be calculated as follows: a first grid of square or rectangular cells of length L1 is positioned over the geometry of the curve such that the grid completely covers the curve. The number of cells (N1) in the first grid that is at least includes a portion of the curve is counted. Next, a second grid having square cells of length L2 is similarly arranged to completely cover the geometry of the curve, and the number of cells (N2) in the second grid including at least part of the curve is counted. In addition, the first grid and the second grid should be located within a minimum rectangular area that includes the curve such that no entire row or entire column on the circumference of one of the grid will miss including at least a portion of the curve.

The first grid preferably contains at least twenty-five cells and the second grid preferably contains four times the number of cells as the first grid. The length (L2) of each square cell in the second grid should be half the length (L1) of each square cell in the first grid. The grid dimension (Dg) can then be calculated using the equation below:

To the For purposes of this application, the term grid dimension curve will be used used to describe a curve geometry that has a grid dimension has that bigger than one is (1). The bigger the Grid size is the higher is the degree of miniaturization passing through the grid dimension curve in terms of an antenna can be achieved at a specific frequency or wavelength is working. In addition, a grid dimension curve may also be in some cases the requirements of a space filling curve, as defined above. For the purpose of this application Therefore, a space fill curve is a type of grid dimension curve.

9 shows an exemplary, two-dimensional antenna 1600 which forms a grating dimension curve with a grating dimension of approximately two (2). 10 shows the antenna 1600 from 9 that in a first grid 1700 which has thirty-two (32) square cells each having a length L1. 11 shows the same antenna 1600 that in a second grid 1600 which has one hundred and twenty-eight (128) square cells, each having a length L2. The length (L1) of each square cell in the first grid ( 1700 ) is twice the length (L2) of each square cell in the second grid 1800 (L2 = 2 × L1). A review of 11 and 12 shows that at least a portion of the antenna 1600 within each square cell in both the first grid 1700 as well as the second grid 1800 is included. The value of N1 in the above grid dimension (Dg) equation is thirty-two (32) (ie, the total number of cells in the first grid 801 ) and the value of N2 is one hundred twenty-eight (128) (ie the total value of the cells in the second grid 802 ). Using the above equation, the grid dimension of the antenna 800 calculated as follows:

For a more accurate calculation of the grid size, the number of square cells can be increased up to a maximum value. The maximum number of cells in a grid depends on the resolution of the curve. As the number of cells reaches the maximum, the grid dimension calculation becomes more accurate. However, if a grid having more than the maximum number of cells is selected, the accuracy of the grid dimension calculation starts to decrease. Typically, the number of cells in a grid 1000 (1000).

For example, shows 12 the same antenna 1600 that in a third grid 1900 is enclosed with five hundred and twelve (512) square cells, each having a length L3. The length (L3) of the cells in the third grid 1900 is half the length (L2) of the cells in the second grid 1800 , this in 8th is shown. As noted above, a portion of the antenna is 1600 within each square cell in the second grid 1800 included, which is why the value of N for the second grid 1800 one hundred twenty-eight (128) is. A review of 12 however, reveals that the antenna is within only five hundred and nine (509) of the five hundred and twelve (512) cells of the third grid 1900 is included. The value of N for the third grid 1900 is therefore five hundred and nine (509). Under the use of 11 and 12 For example, an accurate value for the grid dimension (D) of the antenna can be obtained as follows:

13 and 14 show an alternative example of how the cell count dimension is calculated.

The Antenna has a line pattern, of which at least a portion contains a curve, and the curve has at least five Segments, wherein each of the at least five segments at an angle with each adjacent or abutting Segment forms in the curve, with at least three of these segments shorter as a tenth of the longest Space operating wavelength the antenna is. Every angle between adjacent segments is less than 180 ° and at least two are the angles between adjacent sections less than 115 ° and wherein at least two of the angles are not equal. The curve fits in a rectangular area, with the longest side of the right-angled Area less than a fifth the longest Space operating wavelength the antenna is.

One aspect of the present invention is the cell count dimension of the curve that forms at least a portion of the antenna. For a given geometry lying on a surface, the cell count dimension is calculated in the following manner: First, a grid of cells of size L1 is placed over the geometry such that the grid completely covers the geometry, and the number of cells N1, which contain at least one point of the geometry is counted; second, a grid of cells of size L2 (L2 is smaller than L1) is also placed over the geometry such that the grid completely covers the geometry, and the number of cells N2 containing at least one point of the geometry is again counted. The box count dimension D is then calculated as follows:

With Related to the present invention is the cell count dimension by placing the first grid and the second grid inside of the minimum rectangular area including the curve of the antenna, and calculated by applying the algorithm explained above.

The first grating should be selected such that the right-angled or rectangular area in a field of at least 5 × 5 boxes or cells is split, and the second grid should be like that to be selected, that L2 = 1/2 L and such that the second grid at least 10 × 10 Contains cells. By the minimum, rectangular area is meant an area where there is no entire row or entire column on the perimeter of the lattice that gives a piece does not contain the curve. Some of the embodiments of the Therefore, the present invention has a cell count greater than 1.17, and in the applications where the required degree of miniaturization higher is, the constructions have a cell count dimension of 1.5 to 3 inclusive enough. In some embodiments For example, a curve having a cell count size of about 2 is preferred. For very small antennas, e.g. in a triangle with a maximum size equal a twentieth of the longest Space operating wavelength of the antenna, the cell count size must necessarily be be calculated with a finer grid. In these cases will taken the first grid as a grid of 10 × 10 same cells, while the second grid is taken as a grid of 20x20 same cells and then D becomes according to the above mentioned Equation calculated. In the case of small packs with planar Constructions, that is, constructions in which the antenna is in a single layer is arranged on a package substrate, it will preferred that the dimension of the curve in the antenna geometry is contained, has a value close to D = 2.

in the general applies to a given resonant frequency of the antenna, that the degree of miniaturization, which is achieved by the antenna, the higher the larger the Cell counting dimension is. A way to improve the miniaturization capability of Antenna according to the present invention Invention is the segments of the curve of the antenna pattern to arrange such that the curve at least one point or place from at least 14 cells of the first grid, with 5 × 5 boxes or cells include the curve. In other embodiments, where a higher Degree of miniaturization is required, the curve intersects at least one of the cells twice within the 5x5 grid, that is, containing the curve two, non-adjacent sections within at least one of Cells or boxes of the grid.

Claims (15)

Antenna system for a motor vehicle, comprising: at least a roof rack that is constructed such that it is installed on a motor vehicle can be, with the roof rack a enclosed, inner surface and a ground connection for connecting an antenna element contains the earth of the motor vehicle, and an antenna element passing through the enclosed, inner surface the roof rack is held and electrically coupled to the ground connection. An antenna system according to claim 1, wherein the inner surface is bent and wherein the antenna element adapted to the curved surface is. An antenna system according to claim 1 or claim 2, wherein the antenna element on a surface a flexible substrate is formed, which is adapted to the inner surface is. An antenna system according to any one of the preceding claims, wherein it has an active system which comprises amplifying means for amplifying a electrical signal received from the antenna element becomes. An antenna system according to claim 4, wherein the active Module housed inside the roof rack is. An antenna system according to any one of the preceding claims, wherein it is a reversing camera contains that held by the roof rack is. An antenna system according to any one of the preceding claims, wherein the antenna element has the shape of a space filling curve. An antenna system according to claim 1 or claim 7, wherein the antenna element has the shape of a Hilbert curve. Antenna system according to one of claims 1 to 6, wherein the antenna element is in the form of a lattice dimension curve Has. Antenna system according to claim 7 or claim 9, wherein the curve is a cell count dimension or has a grid dimension that is larger than Is 1.5. Antenna system according to claim 7 or claim 9, wherein the curve is a cell count dimension or a grid dimension greater than Has 1.9. An antenna system according to any one of the preceding claims, wherein the antenna element for the reception of AM / FM bands is adjusted. An antenna system according to any one of the preceding claims, wherein the antenna element for adapted the reception of DAB / TV and GSM bands is. An antenna system according to any one of the preceding claims, wherein the antenna element for is adapted to receive satellite signals: GPS and SDARS bands. An antenna system according to any one of the preceding claims, wherein it has two roof racks, each provided with an antenna element, and wherein the Antenna system further comprising means for combining the signals which are received by the antenna elements.