DE102021203543B3 - Antenna device for a mobile radio device - Google Patents

Abstract

The invention relates to an antenna device (10) with a flat base plate (12) and a first antenna unit (14), the first antenna unit (14) having an antenna plate (16) and spacers (18) arranged parallel to the base plate (12) at a distance, wherein the antenna plate (16) and the base plate (12) are connected in an electrically conductive manner by means of the spacer (18), the base plate (12) having a length (20) and a width (22) of the base plate (12) that are larger than the dimensions Antenna plate (16), wherein the spacer (18) is arranged in the region of a first edge (24) of the antenna plate (16). The invention provides that the antenna unit (14) has a connection plate (26) which is arranged on a second edge (28) of the antenna plate (16), which is opposite the first edge (24), in the area of which the spacer (18 ) is arranged, wherein the connection plate (26) and the spacer (18) protrude in the same direction from the antenna plate (16) and are electrically conductively connected to the antenna plate (16).

Description

The invention relates to an antenna device with a flat base plate and a first antenna unit, the first antenna unit having an antenna plate arranged spaced parallel to the base plate and a spacer arranged between the base plate and the antenna plate, the base plate, the antenna plate and the spacer being designed to be electrically conductive , wherein the antenna plate and the base plate are electrically conductively connected by means of the spacer, wherein the base plate has larger dimensions than the antenna plate in a length and a width of the base plate, the spacer being arranged in the region of a first edge of the antenna plate. In addition, the invention also relates to a mobile radio device with an antenna device.

U.S. 2004/0 196 195 A1 and DE 20 2017 004 886 U1 relate to antenna devices.

Antenna devices as well as mobile radio devices of the generic type are extensively known in the prior art, so that there is no need for separate printed proof of this. Mobile radio devices are not only mobile radio terminals such as a smartphone or the like, but they can also be mobile radio devices from vehicles, in particular motor vehicles, which are used to establish a mobile radio communication link between the vehicle or motor vehicle and a transmitting/receiving station of a mobile radio network. Mobile radio is usually based on the use of radio signals, for example radio signals in predetermined frequency ranges, for example for the mobile radio standard LTE (long term evolution), in particular a frequency range between 698 and 960 MHz known as the lower band, a frequency range between 1, 7 GHz and 2.69 GHz, as well as a frequency range between 1.425 and 1.7 GHz, known as the middle band. However, the division into upper band and middle band is optional. In addition, the use of frequencies in the range greater than 3 GHz is planned, for example for the 5G mobile communications standard.

Mobile radio devices, in particular for mobile radio terminals or also vehicle-supported mobile radio devices, should be as compact as possible. At the same time, antenna devices for the mobile radio devices should be as compact as possible and enable sufficiently good use for as many frequency ranges as possible. The requirement for compactness means that a mobile radio device should generally only have one antenna device, which should be suitable for use in as many frequency ranges as possible. This requires special measures in order to be able to realize the requirement of compact spatial dimensions at the same time. In this context, for example, disclosed EP 3 734 755 A1 a combination antenna for in-vehicle cellular services.

It is known in the prior art to use so-called PIF antennas in mobile radio devices. PIF antennas (PIFA, English: planar inverted F-shaped antenna) are compact antennas which are particularly suitable for use in mobile radio systems. The PIF antenna allows a particularly flat design to be provided and at the same time can be produced inexpensively, which can also be at least partially integrated into a printed circuit board. The antenna properties are determined, among other things, by the geometry and arrangement of the electrical conductors and their spacing on the printed circuit board.

With suitable designs, the PIF antenna can be set up for use in a number of frequency bands that differ from one another. Therefore, the PIF antenna can also be used particularly well for mobile communications. The PIF antenna has a geometrically regularly arranged F-shaped basic pattern, with the specific dimensions depending on the respective resonant frequencies. Several of these PIF antennas can be spatially combined with one another. In addition, L-shaped or U-shaped slots can be provided in a base plate, with designs of this type generally not spanning the slot or slots by the combination of antenna plate, spacer and connection plate. Such a PIF antenna is disclosed, for example, by "Ultra-wideband planar inverted-F antenna (PIFA) for mobile phone frequencies and ultra-wideband applications", Ricardo Gömez-Villanueva et al., Progress In Electromagnetics Research C, Vol. 43 , pages 109 to 120, 2013.

Even if this state of the art has proven itself, there still remains a need for improvement. It is also desirable, especially in vehicles, to largely avoid antenna devices for mobile radio applications in the external appearance of the vehicle. This results in the requirement that the dimensions of the antenna device should be as small as possible. In some installation cases, the problem can arise that only a small base area or only a small overall height is available for mounting the antenna. Therefore, monopole type antennas as well as classic IF antennas with a large bandwidth for mobile communications cannot be located in such restricted areas. Antenna devices with printed circuit board control, as in mobile radio terminals, generally have disadvantageous properties with regard to antenna characteristics that are difficult to control. This applies in particular to the proximity of metal parts, as is usually the case with vehicles. Antennas for mobile radio terminals usually use antenna matching networks in order to adapt the antenna adaptively or dynamically to an actively used frequency band. For automotive applications, this is basically only possible to a very limited extent. Rather, the robustness with regard to antenna properties in antenna devices for automotive applications proves to be critical, because stable connection conditions to base stations of the mobile radio network must be achieved for all vehicle directions with specific environmental conditions.

In addition, it should be considered that, particularly in the automotive industry, the same antenna device should be able to be used in different vehicle series. It should always be possible to achieve the same functionality as far as possible, regardless of the installation location in the vehicle.

It is therefore the object of the invention to improve a generic antenna device and a generic mobile radio device especially for use in vehicles, in particular motor vehicles.

As a solution, an antenna device and a mobile radio device according to the independent claims are proposed with the invention.

Advantageous developments result from features of the dependent claims.

With regard to a generic antenna device, the invention proposes in particular that the antenna unit has a connection plate, which is arranged on a second edge of the antenna plate, which is opposite the first edge, in the region of which the spacer is arranged, the connection plate and the spacer protrude in the same direction from the antenna plate and are electrically conductively connected to the antenna plate.

With regard to a generic mobile radio device, the invention proposes in particular that the antenna device be designed according to the invention.

What can be achieved with the invention is that the antenna device basically combines three different antenna types for two different frequency ranges. The invention allows the antenna characteristic to be decoupled from surrounding metal parts, at least in part, much better than the prior art, so that a significant improvement in the reception and/or transmission properties can be achieved in particular for use in a vehicle, in particular in a motor vehicle . An antenna device with a very small overall height in a range from approximately 5 mm to approximately 17 mm, preferably in a range from approximately 8 mm to approximately 12 mm, with very good antenna properties can be achieved particularly advantageously. As a result, the invention can of course be used in particular in vehicles of the most varied designs, without the need for significant design-specific adaptations to be made for this purpose.

The base plate can be formed by a metal plate or the like. However, the base plate can also be part of a printed circuit board or the like. The base plate is formed from a material that preferably has particularly good electrical conductivity, for example copper, aluminum, silver, alloys thereof and/or the like. Of course, the base plate can also be formed from another electrically conductive material, for example a ferrous metal, a plastic with good electrical conductivity or the like. With regard to the material, the same preferably also applies to the other elements of the first antenna unit, for example in addition to the base plate, the spacer, the connection plate and, if appropriate, other elements of the first antenna unit.

The antenna unit is thus electrically conductively connected to the base plate of the antenna device. The antenna unit preferably has a specific construction comprising an antenna plate having two opposite edges, namely a first edge on which the spacer is arranged and a second edge opposite thereto on which a connection plate is arranged.

The connection plate not only serves to connect the antenna device or the antenna unit, but also has an antenna functionality at the same time. The plates and the spacer of the antenna unit can preferably be formed by planar, flat components, as can the base plate. Preferably, the antenna plate is essentially rectangular. This can also be provided for the base plate. Of course, the antenna plate and the base plate can also be at least partially round be formed, depending on which properties are currently desired. The shape of the base plate, the antenna plate, the terminal plate and the spacer can affect the properties of the antenna device.

For example, the spacer can be formed integrally with the antenna plate and be an element which is formed angled substantially at an angle, preferably at right angles, from the antenna plate towards the base plate. Basically, this of course also applies to the connection plate, which can also be designed in one piece with the antenna plate. Basically, these elements can of course also be designed as separate components that are electrically conductively connected to the antenna plate by means of a connection method, for example welding, soldering, gluing using an electrically conductive adhesive and/or the like.

The spacer and the connection plate protrude in the same direction from the antenna plate. However, the terminal plate does not need to contact the base plate. The connection plate is preferably designed to be electrically isolated from the base plate. Basically, however, there is the possibility of at least partially integrating a connection of the antenna device into the base plate and providing a corresponding connection point by means of the base plate, which can be electrically connected to the connection plate.

According to the invention, it is proposed that a first electrically insulating area be formed in the base plate in an area of the base plate between the spacer and the connection plate. This electrically isolating area can allow the operation of three different antenna types for the two frequency ranges. These three antenna types can be formed by the antenna unit, the electrically insulating area and a mode excitation in the base plate. As a result, high-frequency modes in the area of the base plate can be excited in a particularly specific and favorable manner. Basically, a specific antenna type can be realized in this way. This is because the antenna device formed in this way can achieve a PIFA structure which can electromagnetically couple and excite the additional antenna formed by the electrically insulating area. As a result, the bandwidth of the antenna device can be improved during normal operation. Overall, this refinement makes it possible to provide a relatively small antenna, in particular with a small overall height, which has a particularly favorable effect in the lower band, for example in a frequency range from approximately 600 MHz to approximately 960 MHz. The PIF antenna can then provide a particularly good antenna characteristic for the medium frequency range and the high frequency range, for example in a range from approximately 1.5 GHz to approximately 5 GHz.

In the present case, the antenna characteristic means reception and/or transmission properties of the antenna, for example an antenna gain or the like, preferably depending on the spatial directions of the emission or reception.

Overall, the antenna device designed according to the invention has an almost uniform antenna characteristic with only small lobes under the base plate. A particularly good decoupling from metal parts, in particular below the base plate, can therefore be achieved with this construction. The antenna device that can be provided in this way can thus be designed very compactly, so that it can be easily integrated into vehicles, in particular motor vehicles. Due to the electromagnetic coupling of the antenna formed by the electrically insulating area on the one hand and the PIF antenna and specific main polarization directions on the other hand, it can be achieved that the antenna types formed as a result do not interfere with one another. In addition, what can be achieved is that complex settings in relation to the antenna device and its coupling can be largely reduced. The antenna device is therefore particularly suitable for MIMO applications (English: multiple input multiple output).

The geometry of the electrically insulating area is preferably adapted to the desired frequencies or the desired frequency range. Of course, this also applies to the dimensions of the antenna unit and its elements.

The base plate has a length and a width that are larger than the corresponding dimensions of the antenna plate. The base plate thus protrudes beyond the antenna plate with regard to the extension in the plane of the plate. In terms of direction, the length and the width thus relate to the directions of extension in the plane of the plate.

The electrically insulating area is therefore at least partially formed in an area of the base plate that is covered by the antenna plate transversely to the extent of the base plate or the antenna plate.

According to the invention, the first electrically insulating area is designed as a slot, the length of which is greater than the length of the antenna plate. In this way, a particularly favorable function can be achieved, especially since the antenna unit can be used to couple in with regard to the antenna type formed by the slot. The frequency range for which this type of antenna is particularly active can be determined at least in part by the geometry of the slot.

Furthermore, it is proposed that the first electrically insulating area is designed as a slit, the width of which is smaller than the width of the antenna plate. As a result, the effect of the antenna device can be further improved. The width of the slot can also preferably be determined as a function of the desired frequency range.

According to a further development, it is proposed that the base plate is designed as a base and the slot is designed to be open towards an edge of the base. A further improvement in the function can thereby be achieved, in particular an improvement in the bandwidth in the subband. The antenna characteristic of the antenna device can thereby be further improved. For example, the base can have a height that is smaller than the distance between the base plate and the antenna plate. Preferably the distance is less than about 50% of the distance between the base plate and the antenna plate. Furthermore, the antenna effect of the slot can be further improved by the slot open towards the edge of the base.

The slot can be open in principle, for example in the manner of a through-opening. However, the slot can also be at least partially filled with a suitable electrically non-conductive material, for example a plastic, a ceramic, a composite material and/or the like.

According to a development, it is proposed that the antenna device has an electrically conductive base, the base plate being arranged spaced parallel to the base plate. A further improvement in the antenna characteristic can be achieved in this way. Basically, the base plate and the base plate can be formed from the same material. Preferably, the length and/or the width of the base plate is substantially the same as that of the base plate. In principle, however, the base plate can also be made larger than the base plate, in particular with regard to length and width. The distance between the base plate and the base plate can be smaller than the distance between the base plate and the antenna plate, for example. Preferably, the distance between the base plate and the base plate is less than about 50% of the distance between the base plate and the antenna plate.

In addition, it is proposed that the base plate has a second insulating area, which is arranged in the area of the position of the first electrically insulating area. Preferably, the first and second electrically insulating regions have substantially the same length and width dimensions. Of course, the second electrically insulating area can also have a greater length and/or a greater width than the first electrically insulating area. Basically, the design options that have been specified in relation to the first electrically insulating area and in particular in relation to the slot also apply equally to the second electrically insulating area. Of course, the first and the second electrically insulating region need not be of the same design.

Furthermore, it is proposed that the second insulating region is designed as a slot and the slot is designed to be open towards an edge of the base plate. In this regard, essentially the same advantages and effects apply as have already been stated for the first electrically insulating region, which is why reference is additionally made to the relevant statements.

It is also proposed that the base has a base plate on which at least one base spacer is arranged, which is electrically conductively connected to the base plate and the base plate. The distance between the base plate and the base plate can be fixed by means of the base spacer. For example, several socket spacers can be provided, which are arranged, for example, along a longitudinal extent of the slot. The base spacers can be separate elements that can be designed like the spacer between the antenna plate and the base plate. A corresponding connection can also be provided.

According to one development, it is proposed that an antenna connection be formed on a fourth edge of the connection plate, which is opposite a third edge of the connection plate, on which the electrically conductive connection of the connection plate to the antenna plate is formed. The fourth edge may have a curved curve. The course of the curve can, for example, be exponential, circular, elliptical and/or the like. This antenna port can provide the connection point of the antenna device. The antenna connection can, for example, be approximately in the middle of the fourth be formed or provided edge. Depending on requirements, however, it can also be positioned deviating from the central arrangement. Preferably only this one antenna connection is provided. The antenna device therefore does not need to have any further connection points. The entire antenna device can be electrically coupled to a transmitter/receiver unit of the mobile radio device via this single antenna connection in order to be able to provide the desired functionality. The construction of the antenna device allows all of the antenna types designed to be operated exclusively via this single connection point. Thereby, the configuration of the antenna device can be further improved.

In addition, it is proposed that the base plate has an antenna connection line, which is connected with a first end to the antenna connection of the connection plate. In this configuration it is provided that the base plate at least partially also provides a part of the antenna connection line, and in particular also a connection point which can be electrically coupled to the antenna connection of the connection plate. As a result, a particularly favorable connection of the antenna connection or the antenna device can be achieved.

Furthermore, it is proposed that at least one electronic component for providing an adaptation of an impedance of the antenna connection to an impedance of the antenna connection line is arranged on the base plate. In this configuration, a simple adaptation can be achieved at the antenna connection, so that in particular a characteristic impedance of a connected line can be easily adapted to a characteristic impedance of the antenna device. This can further improve the effect and function of the antenna device. For example, the component can be a passive electronic component. Depending on requirements, several components can of course also be provided here, which form a network, for example. Basically, however, active electronic components can also be provided, for example one or more transistors, one or more diodes and/or the like, which are connected to one another in a suitable manner in order to be able to implement the desired adaptation functionality. Basically, of course, an amplification function can also be provided here if this is desired, for example in order to be able to achieve a favorable signal-to-noise ratio or the like.

According to a development, it is proposed that the antenna device has a second antenna unit, which is arranged on the base plate at a distance from the first antenna unit. With this configuration, the function of the antenna device can be further improved. In particular, a particularly favorable implementation for MIMO can be achieved in this way if the two antenna units can be fed separately, for example. For this purpose, the two antenna units can be connected to respective connection lines for the antenna device so that they can be controlled independently of one another. At the same time, the very compact construction, in particular with regard to a small overall height, can still be implemented. In addition, of course, provision can also be made for the two antenna units to have respective connection plates, which can be connected together to a connection line for the antenna device.

As a result, additional functionality can be achieved overall with very compact dimensions. The two antenna units can, of course, be of identical design, for example. In principle, however, the antenna units can also have different dimensions from one another. The two antenna units are preferably arranged on the same surface of the base plate. For example, they can be arranged side by side on the base plate. In particular, they can be arranged diametrically opposite one another on the base plate. Furthermore, the antenna units can have essentially the same orientation on the base plate. However, they can also be arranged rotated relative to one another. Depending on the alignment of the antenna units, the slot antennas can also be formed in the base plate.

The advantages and effects specified for the antenna device according to the invention naturally also apply equally to the mobile radio device equipped with the antenna device and vice versa.

The invention also includes developments of the mobile radio device according to the invention, which has features as have already been described in connection with the developments of the antenna device according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

The invention also includes the combinations of features of the described embodiments.

• 1 eine schematisch perspektivische Darstellung einer ersten Ausgestaltung für eine Antennenvorrichtung;
• 2 eine schematische Darstellung wie 1 für eine zweite Ausgestaltung einer Antennenvorrichtung;
• 3 eine schematische Draufsicht auf eine dritte Ausgestaltung einer Antennenvorrichtung mit einem Sockel;
• 4 eine schematisch perspektivische Darstellung der Antennenvorrichtung gemäß 3;
• 5 eine schematische Diagrammdarstellung eines Reflexionsparameters an einem Antennenanschluss der Antennenvorrichtung gemäß einer der vorhergehenden Figuren;
• 6 eine schematische Diagrammdarstellung wie 5, jedoch unter Nutzung eines Anpassungsnetzwerks;
• 7 eine schematische Diagrammdarstellung eines Ortskurvendiagramms zur Darstellung einer Antennencharakteristik bei einer ersten Betriebsfrequenz;
• 8 eine schematische Diagrammdarstellung wie 7 bei einer zweiten Betriebsfrequenz;
• 9 eine schematische Diagrammdarstellung eines linearen Mittels über einem Azimutgewinn bei einem Neigungswinkel von 80° für unterschiedliche Umgebungen;
• 10 eine schematisch perspektivische Ansicht einer vierten Ausgestaltung einer Antennenvorrichtung mit einem Sockel;
• 11 eine schematisch perspektivische Darstellung wie 10 einer fünften Ausgestaltung einer Antennenvorrichtung, jedoch mit zwei Antenneneinheiten; und
• 12 eine schematische Darstellung einer Mobilfunkeinrichtung mit einer Antennenvorrichtung.

An exemplary embodiment of the invention is described below. For this shows:

• 1 a schematic perspective representation of a first embodiment for an antenna device;
• 2 a schematic representation of how 1 for a second embodiment of an antenna device;
• 3 a schematic plan view of a third embodiment of an antenna device with a base;
• 4 a schematic perspective view of the antenna device according to FIG 3 ;
• 5 a schematic diagram representation of a reflection parameter at an antenna connection of the antenna device according to one of the preceding figures;
• 6 a schematic diagram representation like 5 , but using a matching network;
• 7 a schematic diagram representation of a locus diagram for representation of an antenna characteristic at a first operating frequency;
• 8th a schematic diagram representation like 7 at a second operating frequency;
• 9 Figure 12 is a schematic diagram representation of linear mean versus azimuth gain at 80° tilt angle for different environments;
• 10 a schematic perspective view of a fourth embodiment of an antenna device with a base;
• 11 a schematic perspective view like 10 a fifth embodiment of an antenna device, but with two antenna units; and
• 12 a schematic representation of a mobile radio device with an antenna device.

The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention to be considered independently of one another, which also develop the invention independently of one another and are therefore also to be regarded as part of the invention individually or in a combination other than the one shown. Furthermore, the embodiment described can also be supplemented by further features of the invention already described.

Elements with the same function are each provided with the same reference symbols in the figures.

1 FIG. 1 shows a first configuration for an antenna device 10 in a schematic perspective representation. The antenna device 10 has a flat base plate 12, which in the present case is formed from a metal, for example from a copper alloy. In alternative configurations, the material of the base plate 12 can of course also vary. In the present case, the base plate 12 essentially has an approximately rectangular shape. An antenna unit 14 is arranged on an upper side of the base plate 12 .

The antenna unit, here the first antenna unit 14 , has an antenna plate 16 arranged spaced parallel to the base plate 12 and a spacer 18 arranged between the base plate 12 and the antenna plate 16 . In the present case, the antenna plate 16 and the spacer 18 are formed from the same material as the base plate 12 . The base plate 12, the antenna plate 16 and the spacer 18 are thus designed to be electrically conductive, so that the antenna plate 16 and the base plate 12 are electrically conductively connected by means of the spacer 18. The base plate 12 has a length 20 and a width 22 which are each greater than the corresponding length 20 or width 22 of the antenna plate 16 . The spacer 18 is arranged in the area of a first edge 24 of the antenna plate 16 .

Out of 1 It can also be seen that the antenna unit 14 has a connection plate 26 which is arranged on a second edge 28 of the antenna plate 16 which is opposite the first edge 24 in the region of which the spacer 18 is arranged. The connection plate 26 and the spacer 18 protrude in the same direction from the antenna plate 16 and are electrically conductively connected to the antenna plate 16 . The connection board 26 is connected to the antenna board 16 at an edge 50 of the connection board 26 . An antenna connection 52 is formed on an edge 48 of the connection plate 26 opposite this edge 50 . In the present case, the connection plate 26 is also formed from the same material as the antenna plate 16 . The plates 12, 16, 26 are formed overall from a material with a thin material compared to the length 20 and the width 22 with a small thickness. For example, the thickness of the plates may range from about 0.6 mm or less.

In a first area of the base plate 12, there is a first electrically insulating area 30 between the spacer 18 and the connection plate 26 designed in the manner of a slot 32, the length of which is greater than the length of the antenna plate 16. In addition, the width of the slot 32 is smaller than the width of the antenna plate 16.

For the intended application in the field of mobile communications, the base plate in the present embodiment has, for example, a length of approximately 80 mm and a width of approximately 80 mm as well. The height of the entire antenna device is only about 14 mm, with the antenna plate 16 being spaced from the base plate 12 by about 12 mm. Provision can also be made, for example, for the length to be approximately 80 mm and the width to be approximately 90 mm.

In a vehicle or motor vehicle, the base plate 12 is preferably arranged essentially in a free area. However, further metal parts or a metal body or the like can be arranged below the base plate 12 . Using the antenna device 10 according to the invention, smaller dimensions can be achieved than in mobile radio terminals with regard to a length, a width and in particular a height. Incidentally, this also applies to the further examples discussed below.

Even if the base plate 12 in accordance with the present embodiment 1 is essentially rectangular, the invention is not limited to this. The base plate 12 can therefore also have a different contour, in particular an at least partially rounded contour.

In the present case, the slot 32 is designed to be open towards an edge 56 of the base plate 12 . In the area of the edge 56, the slot 32 is connected to an opening area 58, so that a smaller width 22 can be realized in the area of the edge 56. In this embodiment, the slot 32 is formed by a through hole through the base plate 12 in which no material other than air is placed. In alternative configurations, a suitable material can of course also be arranged at this point, for example an electrically insulating material such as plastic, ceramic or the like.

In the present case, the slot 32 has a length of approximately 70 mm and a width of approximately 15 mm. In the present case, the slit itself is essentially in the form of a rectangle. However, its shape can also vary, especially in terms of dimensions. For example, the slot can also have a length in a range from about 60 mm to about 80 mm and a width in a range from about 5 mm to about 30 mm, depending on an available assembly volume, for example.

The mouth region 58 adjoins the slot 32 so that the slot 32 is open towards the edge 56 of the base plate 12 . In the present case, the opening area 58 has a length of approximately 10 mm and a width of approximately 4 mm. The length of the mouth portion 58 may depend on the position of the slot 32, for example, and in this embodiment may be in a range from about 5 mm to about 20 mm or even more, for example. In alternative embodiments, the width of the mouth portion 58 may range from about 1 mm to about 10 mm.

The slot 32 can implement an additional antenna functionality by means of the base plate 12, in particular by exciting modes on the base plate, so that an antenna functionality can be improved, particularly in the lower frequency band of mobile communications.

The antenna functionality provided by the slot 32 can be excited by the antenna unit 14 . This type of excitation makes it possible to increase the operating bandwidth so that the entire usable bandwidth can be used for mobile communications.

The antenna unit 14 provides an IFA structure whose height relative to the base plate 12 is determined by the spacer 18 . In this embodiment it is provided that the antenna plate 16 is positioned approximately 12 mm above the base plate 12 . In alternative configurations, however, the height can also be selected in a range from approximately 10 to approximately 20 mm. It can preferably be 15 mm. In this embodiment, it is also provided that the antenna plate 16 has a length of approximately 40 mm and a width of approximately 17 mm. Basically, however, it can also be provided that a ratio between the width and length of the antenna plate 16 is approximately 0.1, 0.2, 0.3, 0.4, 0.6 or more.

It has been shown that the antenna characteristic of the slot antenna with a feed via the PIF antenna according to the antenna unit 14 in the lower frequency band of mobile communications is approximately the same as can be achieved with a typical slot antenna. In particular, it may have a toroidal shape with a chief ray in directions transverse to the slot.

In the medium and high-frequency frequency range of the frequency bands provided for mobile radio, the behavior of the IF antenna, that is, the antenna unit 14, determines the behavior of the antenna device 10. It provides such Bandwidth due to the shape of terminal plate 26, which here has exponentially shaped edge regions. The exponential form allows a wide bandwidth, which is why it is particularly preferred. In principle, however, the shape can also be angular, for example triangular, semi-circular or semi-elliptical.

The antenna characteristic of the antenna device 10 is comparable to that of an ordinary IF antenna arranged on a narrow base plate, particularly at frequencies above 1.5 GHz. Since radiation below the base plate 12 is very low, any metallic objects below the base plate 12 have only a small influence on the antenna characteristics, for example in relation to the upper hemisphere, especially at small elevation angles, which are usually the most critical for a stable communication link to a cellular base station. Because of the sophisticated design of the IF antenna, the IF antenna usually hardly excites the slot structure in the range of frequencies higher than 1.5 GHz.

• - Die Schlitzstruktur kann für das untere Frequenzband zur Kommunikation genutzt werden. Diese Struktur ist unterhalb der Antennenplatte 16 der Antenneneinheit 14 beziehungsweise IF-Antenne angeordnet. Der offene Schlitz ist deshalb groß genug, um die Funktionalität im Unterband zu ermöglichen. Durch die Nutzung der Schlitzantenne im Unterband kann die PIF-Antenne klein ausgebildet sein. Dies betrifft nicht nur die Länge und die Breite, sondern insbesondere auch die Höhe;
• - Die Antennenvorrichtung 10 erlaubt stabile Antennencharakteristiken besonders bei Frequenzen oberhalb von etwa 1,5 GHz, weil die Antenneneinheit 14 in diesem Frequenzband besonders aktiv ist. Starke Variationen in Bezug auf die Antennencharakteristik bei diesen Frequenzen können vermieden werden, weil die Schlitze hier keine signifikante Wirkung entfalten;
• - Die vertikale metallische Struktur, und zwar die Anschlussplatte 26, der IF-Antenne 14 der Antennenvorrichtung 10 stellt den Speiseteil für den Schlitzantennenbereich und die Antenneneinheit 14 dar. Auf diese Weise ist nur ein gemeinsamer Speisepunkt für die Anregung der PIF-Antenne und der Schlitzantenne erforderlich.

In particular, the construction of the antenna device 10 according to the invention has the following advantages:

• - The slot structure can be used for the lower frequency band for communication. This structure is arranged below the antenna plate 16 of the antenna unit 14 or IF antenna. The open slot is therefore large enough to allow for sub-band functionality. By using the slot antenna in the sub-band, the PIF antenna can be made small. This not only affects the length and width, but also the height in particular;
• - The antenna device 10 allows stable antenna characteristics, especially at frequencies above about 1.5 GHz, because the antenna unit 14 is particularly active in this frequency band. Large variations in the antenna characteristics at these frequencies can be avoided because the slots have no significant effect here;
• - The vertical metallic structure, namely the connection plate 26, of the IF antenna 14 of the antenna device 10 represents the feed part for the slot antenna area and the antenna unit 14. In this way there is only one common feed point for the excitation of the PIF antenna and the slot antenna necessary.

2 FIG. 12 shows a second embodiment for an antenna device 10, which is basically based on the first embodiment 1 is based, which is why in addition to the comments on the first embodiment according to 1 is referenced. Only the differences in relation to the first embodiment are described below 1 explained.

2 12 shows that the base plate 12 is placed on a pedestal 34 formed of a metal such as a copper alloy or the like. The slot 32 is open to an edge 36 of the base 34 . This means that the mouth area 58 extends into the base 34 in this embodiment. A printed circuit board is arranged on the base 34 as a base plate 12 and is coated on both sides with a metallization. In the area of the slot 32, the metallization on the two opposite surfaces of the base plate 12 and the printed circuit board is removed in order to form the slot 32. The slot 32 is filled here with the carrier material of the printed circuit board, which can be FR4, for example.

The mouth area 58 is formed in the base, which enables the slot 32 to be open towards the edge 36 . Basically, the mouth area 58 can also be filled with an electrically non-conductive material such as the carrier material of the circuit board of the base plate 12 . In the present case, however, the mouth area 58 is only filled with air.

The base 34 comprises a base plate 38 which has a collar 60 which runs essentially all the way round. The base plate 38 and the collar 60 form the base 34 in which the mouth area 58 is formed.

Opposite the base plate 38 the printed circuit board is fastened as the base plate 12 on the circumferential collar 60 . The specific external dimensions and the external shape of the antenna device 10 according to 2 are selected according to an installation position in a vehicle or motor vehicle. They can therefore also be varied depending on this.

The base plate 12 has a specifically shaped contour with respect to the slot 32 . The slot 32 opens into the mouth area 58. The functions of the slot 32 and the mouth area 58 essentially correspond to those already described in accordance with the first embodiment 1 was explained, which is why reference is also made in this regard to the previous statements.

The antenna device 10 according to FIG 2 has an antenna unit 14, which essentially corresponds to how it is already based on FIG 1 is explained. The use of a circuit board as a base plate 12 allows additional components ments, in particular electronic components, in order to further improve the function of the antenna device 10, for example to improve an adaptation with respect to an antenna line or the like. By extending the slot 32 into the three-dimensional structure formed thereby, the influence of surrounding metallic vehicle parts on the antenna device 10 can be further reduced.

3 shows a third embodiment for an antenna device 10 in a schematic plan view, which is based on the second embodiment according to FIG 2 is based, which is why reference is also made to the relevant statements. In addition, shows 4 according to a corresponding schematic perspective view of the third embodiment 3 .

With regard to the design according to 2 is in accordance with the design 3 the collar 60 is smaller in scope, so that the printed circuit board serving as the base plate 12 projects beyond it. On the part of the printed circuit board or base plate 12 that protrudes beyond the collar 60, base spacers 46 are arranged, which can be formed, for example, by metal strips, bolts and/or the like made of an electrically conductive material, in particular metal. They are electrically connected to the circuit board or the base plate 12 and at the same time to the base plate 38 . This embodiment proves to be advantageous for series production, for example for mechanical reasons.

The base plate 38 has a slot 42 which is open via a further mouth area 58 to an edge 44 of the base plate 38, that is, to the outside. In the present case, the slot 42 serves as a mainly active antenna element for frequencies in the lower frequency range of mobile communications. The position of the orifice region 58 can affect the resonant frequency of the slot 42 and, for example, reduce it. In addition, the base plate 12 or the printed circuit board can be excited by the thin mouth area 58, so that the resonant frequency can be further reduced, for example.

The base plate 12 or the circuit board has again - as in the second embodiment 2 - a slot 32 on. The slot 32 is formed in that the metallization is correspondingly removed on the opposite sides of the printed circuit board. Both are aligned with one another in the direction of width 22 and/or direction of length 20 . The slot 32 is located a predetermined distance above the slot 42 and the mouth portion 58 . The metallizations of the circuit board or base plate 12 are electrically conductively connected to the base plate 38 . The three-dimensional antenna type construction formed in this way proves to be particularly favorable for use in the lower frequency range of the lower mobile radio band.

The type of antenna formed by the slots 42, 32 and the mouth area 58 can be replaced by the antenna unit 14, which here is the same as in the second embodiment according to FIG 2 is intended to be stimulated. The antenna plate 16 and the spacer 18, which serves as a short-circuit connection, thus span the slot 32. The antenna unit 14 serves as a feed element for the three-dimensional antenna unit formed underneath with the slots 32, 42 and the mouth area 58. At the same time, the antenna unit 14 serves to Range from 1.5 GHz to about 5 GHz to provide a good reliable antenna characteristics.

5 shows a reflection coefficient (S-parameter) as a function of a frequency in a schematic diagram representation. An abscissa is associated with frequency in GHz, while the ordinate is associated with S-parameters in dB. With a graph 66 is in 5 the dependency shown. 5 shows the dependency directly at the feed point, that is, the antenna connection 52. The reference characteristic impedance is 50 Ω in the present case. The graph 66 shows the broadband effect of the antenna device 10.

The structure formed by the slot 32 dominates in the lower frequency band of mobile communications. A range of the middle and upper frequency band of mobile radio is denoted by the reference number 62 . Although a resonance point 64 occurs, the phase-frequency change of the antenna impedance can be adjusted by the position of the muzzle region 58 so that the reflection coefficient better than -5 dB can be achieved within the frequency band from about 600 MHz to about 960 MHz by applying a matching network . This is based on the schematic diagram representation according to 6 shown. 6 shows in a schematic diagram representation as 5 with a graph 68 the corresponding course.

7 shows locus curves for the antenna characteristic in a schematic circular diagram, in particular with regard to far-field gain. A graph 70 shows the conditions with a metal plate below the antenna device 10 . A graph 72 represents the conditions in free space. The diagram according to FIG 7 Figure 12 shows the conditions for an operating frequency of about 800 MHz. The metal plate below the antenna device 10 has dimensions of about 20 cm x 20 cm at a distance of about 5 cm below the antenna device 10.

The antenna characteristic in relation to the lower frequency band in mobile communications corresponds to that of a typical slot antenna. In free space, it can be seen from the graph 72 that there is essentially a toroidal shape here. If a metallic object is arranged below the antenna device 10 in this frequency range, this has a significant influence on the antenna characteristic. This can be seen from the graph 70. The data relates to an antenna device 10 according to the third embodiment 3 How out 7 As can be seen from the graph 70, the antenna characteristic changes in direction with a main characteristic near a zenith in 7 or the angle of 0°.

8th shows in a schematic diagram representation as 7 the conditions at a frequency of about 3.5 GHz. It can be seen here that the metal plate below the antenna device 10 has a significantly smaller effect. Although there is a reduction in the average linear antenna gain at about 80° with about 3 dB in the frequency band from about 600 MHz to about 960 MHz, the antenna characteristic can be essentially constant.

This is also evident from the schematic diagram representation according to FIG 9 shown, in which for the angle of approximately 80° the linear average antenna gain is shown as a function of the frequency for the case of the freely arranged antenna device 10 and the antenna device 10 arranged above the metal plate. Here, too, the dependency - as already mentioned for the 7 and 8th explained - represented by graphs 70 and 72. From the 7 until 9 it can be seen that from a frequency of approximately 1.5 GHz, the antenna unit 14 dominates the functionality and the antenna characteristic of the antenna device 10 . The antenna unit 14 has a large bandwidth because of the exponential shape of the antenna plate 16. This defines an upper frequency limit. The lower frequency limit is determined by the dimensions of the antenna plate 16 or the antenna device 10, in particular by the height, which is determined by the spacer 18.

The main function in the frequency band between about 1.5 GHz and about 2 GHz is provided by the antenna unit 14. However, the slots 32, 42 and the mouth region 58, respectively, add a small portion of the antenna pattern of the antenna device 10. Above about 2 GHz, the antenna pattern essentially corresponds to that of a typical IFA design placed on a small conductive plane. This shows for example 8th . The main radiation occurs in an upper hemisphere, as is required for mobile user applications. Thus, it can be determined that metallic objects below the antenna device 10 have only a small effect on the antenna characteristics in the upper hemisphere, as can be seen from the graph 70 and the graph 72 in FIG 8th is evident.

9 shows in the schematic diagram representation with the graphs 70, 72 that the antenna device 10 at frequencies above approximately 1.8 GHz has a maximum deviation in the mean antenna gain of approximately 1 dB.

10 shows in a schematic perspective view a fourth embodiment as in FIGS 3 and 4 is shown, with only the mouth area 58 being formed at a different position of the base plate 38 . As a result, the excitation of different modes can be achieved in the base plate 12, as a result of which the resonant frequency can be better adjusted.

11 shows in a schematic diagram representation as 10 a fifth embodiment of an antenna device 10, in which a double structure with two antenna units 14 and two slots 32 and respective orifices 58 are provided. Different modes can be excited with the orifice openings 58, so that with the antenna device 10 according to FIG 11 good isolation between MIMO antennas can also be achieved.

12 shows a schematic view of a mobile radio device 54, which has an antenna device 10 according to one of the configurations based on FIG 1 until 4 and 10 or 11 uses.

The exemplary embodiments serve exclusively to explain the invention and are not intended to limit it.

Reference List

10

antenna device

12

base plate

14

antenna unit

16

antenna plate

18

spacers

20

length

22

Broad

24

edge

26

connection plate

28

edge

30

area

32

slot

34

base

36

edge

38

base plate

40

area

42

slot

44

edge

46

socket spacers

48

edge

50

edge

52

antenna connector

54

cellular facility

56

edge

58

mouth area

60

collar

62

area

64

resonance point

66

graph

68

graph

70

graph

72

graph

Claims (12)

Antenna device (10) with a planar base plate (12) and a first antenna unit (14), wherein the first antenna unit (14) has an antenna plate (16) arranged spaced parallel to the base plate (12) and one between the base plate (12) and the antenna plate (16) arranged spacers (18), wherein the base plate (12), the antenna plate (16) and the spacer (18) are electrically conductive, wherein the antenna plate (16) and the base plate (12) by means of the spacer (18 ) are electrically conductively connected, the base plate (12) having larger dimensions than the antenna plate (16) in a length (20) and a width (22) of the base plate (12), the spacer (18) in the region of a first edge (24) of the antenna plate (16), the antenna unit (14) having a connection plate (26) which is arranged on a second edge (28) of the antenna plate (16), which is opposite the first edge (24), in of This region of the spacers (18) is arranged, with the connection plate (26) and the spacer (18) protruding in the same direction from the antenna plate (16) and being electrically conductively connected to the antenna plate (16), characterized in that. in a first area of the base plate (12) between the spacer (18) and the connection plate (26) a first electrically insulating area (30) is formed in the base plate (12), and that the first electrically insulating area (30) as a slot ( 32) is formed, the length of which is greater than the length of the antenna plate (16). antenna device claim 1 , characterized in that the first electrically insulating region (30) is designed as a slot (32) whose width is smaller than the width of the antenna plate (16). antenna device claim 1 or 2 , characterized in that the base plate (12) is arranged on a base (34) and the slot (32) to an edge (36) of the base (34) is designed to be open. antenna device claim 1 or 3 characterized by an electrically conductive base (34) having a base plate (38), the base plate (12) being spaced parallel to the base plate (38). antenna device claim 4 , characterized in that the base plate (38) has a second electrically insulating area (40) which is arranged in the region of the position of the first electrically insulating area (30). antenna device claim 5 , characterized in that the second electrically insulating region (40) is designed as a slot (42) and the slot (42) is designed to be open towards an edge (44) of the base plate (38). Antenna device according to one of Claims 4 until 6 , characterized in that at least one base spacer (46) is arranged on the base plate (38) and is electrically conductively connected to the base plate (12) and the base plate (38). Antenna device according to one of the preceding claims, characterized in that on a fourth edge (48) of the connection plate (26), which is opposite a third edge (50) of the connection plate (26), on which the electrically conductive connection of the connection plate (26) with the antenna plate (16) is formed, an antenna connection (52) is formed. antenna device claim 8 , characterized in that the base plate (12) has an antenna connection line, which is connected with a first end to the antenna connection (52) of the connection plate (26). antenna device claim 8 or 9 , characterized in that at least one electronic component is arranged on the base plate (12) for providing an adaptation of an impedance of the antenna connection (52) to an impedance of the antenna connection line. Antenna device according to one of the preceding claims, characterized by a second antenna unit (14) which is arranged on the base plate (12) at a distance from the first antenna unit (14). Mobile radio device (54) with an antenna device (10), characterized in that the antenna device (10) is designed according to one of the preceding claims.

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