WO2024132052A1

WO2024132052A1 - Antenna device and operating method for the antenna device for locating objects, and motor vehicle having the antenna device

Info

Publication number: WO2024132052A1
Application number: PCT/DE2023/200254
Authority: WO
Inventors: Mario Schuehler; Burak SAHINBAS; Nicholas Christopoulos; Lars Weisgerber; Michael Vaith
Original assignee: Continental Automotive Technologies GmbH
Priority date: 2022-12-19
Filing date: 2023-12-13
Publication date: 2024-06-27

Abstract

The invention relates to an antenna device (11) having four or more than four antenna connections (31) for connecting a respective antenna and having a control circuit (16) which has two or more signal ports (18), characterised in that each of the signal ports (18) is connected by means of a respective switching unit (30) to two or more than two of the antenna connections (31), wherein the respective switching unit (30) is configured to assume, depending on a control signal, one of several predefined switching states (32) in which it keeps the signal port (18), which is connected to said switching unit, electrically connected to another of the antenna connections connected to said switching unit, wherein the control circuit (16) is connected to a corresponding control input of the switching directions and the control circuit (16) has a control logic which, when executed by the control circuit (16), prompts the control circuit to generate the control signal and to apply, to reception signals (17) received via the signal ports, one or alternately at least two different predefined locating methods for respectively locating at least one object.

Description

Antenna device and operating method for the antenna device for locating objects and motor vehicle with the antenna device

The invention relates to an antenna device such as can be provided in a motor vehicle for a radio key system and/or a short-range radar for detecting people. The antenna device has at least four antenna connections for connecting a respective antenna and a control circuit for processing received signals from the antennas. The invention also includes an operating method for the antenna device and a motor vehicle with such an antenna device.

In a motor vehicle, such as a passenger car, an arrangement of several antennas can be provided in order to be able to provide direction-based and/or distance-based localization functions based on radio signals. One such localization function is UWB technology (UWB - ultra wide band) for e.g. radio keys, in order to localize a radio key located in an external environment of the motor vehicle or another device acting as a radio key, such as a smartphone, at least in relation to its distance from the motor vehicle. Another localization function is CPD (child presence detection), which is based on radar technology in that a radio signal is emitted by means of the antenna device and the reflected radio signal is used to evaluate whether a person, in particular a small person, is in the external environment of the motor vehicle.

To implement the respective localization functions, different antenna arrangements or positioning of the antennas are advantageous. Even for a single localization function, it can be advantageous to carry out these functions one after the other using different antennas in order to achieve a more precise localization of an object in an external environment of the However, providing different antenna arrangements in the vehicle results in a correspondingly large amount of circuitry work, which one would like to avoid.

The invention is based on the object of providing one or more localization functions in a motor vehicle with little circuitry effort.

The object is achieved by the subject matter of the independent patent claims. Advantageous further developments of the invention are described by the dependent patent claims, the following description and the figures.

As a solution, the invention comprises an antenna device having four or more than four antenna connections for connecting a respective antenna and having a control circuit having two or more than two signal ports. The antenna device can be implemented, for example, on a printed circuit board (PCB). The control circuit can be provided, for example, as a chipset. An antenna connection can be realized, for example, as a coaxial connection and/or by means of conductor tracks. A signal port can be a receiving port (Rx port) that can receive a received signal from an antenna connected to one of the antenna connections. The signal port can, for example, lead to a signal amplifier of the control circuit. A corresponding chipset with signal ports can be taken from the prior art.

In order to use a rigid antenna arrangement flexibly in different reception constellations, the invention comprises that each of the signal ports is connected (connected) via a switching unit to two or more than two of the antenna connections. In other words, there are more antenna connections than signal ports and each signal port can be connected to a group of several of the antennas via one of the switching units. The antenna connections that lead to one antenna each are therefore grouped, with each connection group being connected via a switching unit. is connected to one of the signal ports. In particular, it is intended that each of the switching units is connected to other antennas.

The respective switching unit is designed to assume one of several predetermined switching states depending on a control signal, in which it then electrically connects or keeps connected the signal port connected to it with another of the antenna connections connected to it. “Switching state” means that the switching unit electrically connects the signal port to one of the antenna connections, while each additional antenna connection has no electrically conductive connection to the signal port. It is therefore provided that only one of the antenna connections is electrically connected to the signal port, and a different one in each of the switching states. By changing the switching state, another of the antenna connections is electrically connected to the signal port. Switching between the switching states can be achieved by means of a control signal at a control input of the respective switching unit.

Accordingly, the control circuit is connected to the respective control input of the switching directions and the control circuit has a control logic which, when executed by the control circuit, causes it to generate the control signal for the switching units. This selects the antennas (antenna connections) whose received signal is forwarded to the signal ports. One or at least two different predefined localization methods are then applied alternately to these received signals received via the signal ports in order to respectively localize at least one object. The "control logic" provided for this purpose can be implemented in the control circuit, for example, as a program and/or on the basis of logic gates and/or by design as an AS IC (Application Specific Integrated Circuit). When the control circuit is in operation, this control logic is then active, i.e., for example, the program is executed. The control circuit then uses the control signal to determine the switching states of the switching units, whereby at each signal port one of the antenna connections is electrically connected to the signal port. The reception signals received via these antenna connections from the antenna connected to it are then passed through to the associated/connected signal port and the received or incoming reception signals are then processed by the currently active localization method. The person skilled in the art can implement a known method from the prior art in the control circuit as the localization method. The decisive factor is that this can be operated alternately with other antenna constellations by switching the switching units. The respective localization method can include a distance measurement and/or a direction estimate. Corresponding localization methods are known from the prior art. For example, a radio key or an electrical device that functions as a radio key, such as a smartphone, can be localized as an object in the manner described if the localization method involves a UWB radio key system. For example, a person, particularly a child, i.e. a person with a height of less than 1.50 meters, can be located as an object if the localization process involves the CPD process described above. According to the regulation, the associated CPD function includes the recognition of children up to 6 years of age, i.e. the limit refers to age.

The invention provides the advantage that, despite a fixed antenna arrangement of antennas connected to the antenna connections, the localization method or several different localization methods with different antenna constellations can still be operated by means of the antenna device by setting corresponding switching states in the switching units. For example, it is sufficient to provide a control circuit with only two signal ports in order to be able to operate one or more localization methods with different antenna constellations, which can be formed with four or more than four antennas, for example. This advantageously reduces the need to provide a separate signal port for each antenna. In other words, each antenna connection is assigned to exactly one signal port with which it can be electrically connected by a corresponding switching state of the intermediate switching unit.

The invention also includes further developments which result in additional advantages.

A further development includes one or more or each localization method providing different switching states of the switching units for different consecutive measurement cycles. In other words, such a localization method does not just perform a single measurement, but repeats several measurements one after the other, each of which represents a measurement cycle. In this case, however, the localization method is then used with different antennas or operated with reception signals from different antennas. The same localization method can thus be carried out with little effort on the basis of different antenna constellations. The localization results from the different measurement cycles can then be advantageously combined to obtain more precise localization.

A further development includes one or more or each localization method for localizing the at least one object comprising a phase-based angle of arrival estimation, AoA (Angle of Arrival), using the received signals sent to the signal ports. By specifying switching states in the switching units, antennas at different distances from one another or antennas with specified distances can be used, so that the received signals used or the corresponding antennas can be selected to match the angle of arrival estimation. A further development comprises that one or more or each localization method comprises that it comprises at least two measurement cycles, both of which comprise the angle of incidence estimation, wherein in the measurement cycles different ones of the antenna connections are connected to the signal ports. Thus, the localization method can carry out two different measurements of the angle of incidence based on different antennas, in particular with antennas that have different distances, wherein the localization results of the different measurement cycles can then be combined, for example by forming an average or by excluding ambiguities in the other localization result based on one of the localization results.

A further development includes one or more or each localization method for localizing the at least one object comprising a runtime-based distance measurement carried out on the signals sent to the signal ports. Such a runtime-based distance measurement can, for example, provide that a transmission signal is transmitted by means of the antenna arrangement and a runtime until an associated or corresponding reception signal is received is measured and from this a distance measurement of the object responding or generating the reception signal is measured.

A further development includes one or more or each localization method comprising at least two measurement cycles, one of which comprises the angle of incidence estimation and another the time-of-flight-based measurement. In such a localization method, two measurement principles are combined. In particular, a different antenna constellation can be set by changing the switching states for each measurement principle (e.g. angle of incidence estimation or time-of-flight-based measurement) without the need for an additional signal port.

A further development involves an antenna being electrically connected to one of the antenna connectors. In other words, the Antenna device also includes the antennas themselves. These antennas can be integrated in a circuit board, for example as a slot antenna or patch antenna, or they can be connected to a circuit board of the control circuit or a circuit board of the antenna connections, for example via coaxial cable.

One or more or each localization method comprises in each case comprising at least two measuring cycles, of which in one of the measuring cycles the signal ports are connected to those of the antennas whose distance is less than or equal to half a wavelength of a transmission frequency of a transmission circuit of the antenna device used in the measuring cycle and in another of the measuring cycles the signal ports are connected to those of the antennas whose distance is greater than half a wavelength of a transmission frequency of the transmission circuit used in the measuring cycle. In other words, in the measuring cycles, a clear measurement with respect to phase offset is made once during a measurement at an antenna distance of less than or equal to half the wavelength, while in the other measuring cycle an ambiguous measurement with respect to phase differences is made due to the distance of the antennas being greater than half the wavelength. Since at least one measuring cycle is carried out on the basis of an antenna distance of less than or equal to half the wavelength, an unambiguous localization result can always be achieved by combining the localization results of the measuring cycles. Using an antenna spacing greater than half the wavelength gives the additional advantage of more precise localization. The transmitter circuit can be part of the control circuit, e.g. part of the chipset in question.

The localization procedure involves generating an ambiguous localization result in the measurement cycle with the antenna distance greater than half the wavelength and making the localization result unambiguous in the measurement cycle with the antenna distance less than or equal to half the wavelength. For example, ambiguous localization results can be excluded or lead to an unambiguous Localization results can be reduced by using the measurement cycle with an antenna spacing of less than or equal to half the wavelength to identify the spatial sector in which one of the ambiguous localization results lies or points. In this way, the advantages of a large antenna spacing (greater than half the wavelength) can be combined with the unambiguous measurement based on an antenna spacing of less than or equal to half the wavelength.

A further development includes the antennas being arranged to form an antenna array in which the antennas are arranged equidistantly with a grid spacing of less than or equal to half the wavelength. An equidistant antenna array advantageously makes it possible to use any two adjacent antennas for a measurement cycle with an antenna spacing of less than or equal to half the wavelength.

An alternative development comprises that only two or only some of the antennas are arranged at a distance of less than or equal to half the wavelength of the transmission frequency and two or some of the antennas are arranged at a distance of greater than half the wavelength from at least one other of the antennas across an antenna-free gap. This has the advantage that a measurement cycle can be carried out with an antenna distance that is significantly greater than half the wavelength, for example more than twice half the wavelength. However, since there is at least one antenna pair whose antenna distance is less than or equal to half the wavelength, ambiguous localization results from one of the measurement cycles can always be disambiguated or made unambiguous using this antenna pair in another measurement cycle. For example, the spatial sector in which the object is located can be identified without precise localization being possible using this antenna pair (antenna distance less than or equal to half the wavelength). For this purpose, another antenna pair with an antenna spacing greater than half the wavelength can be used, for which, however, the described ambiguous localization result, which can then be disambiguated.

A further development includes at least one of the signal ports being additionally designed as a transmit and receive port (Tx-Rx port), which generates a transmit signal to emit via the currently electrically connected antenna to generate the receive signals and then receives one of the receive signals in a receive mode. In other words, no additional signal port is required to achieve active localization, i.e. location, using a transmit signal. Instead, a signal port is switched to transmit and the transmit signal (radio signal) is transmitted and then the signal port is switched to receive and the response signal or reflection signal, i.e. the radio signal or transmit signal reflected from the at least one object, is received as a receive signal and fed to the signal port. Thus, with two signal ports, both the transmission of a transmit signal and the reception of two receive signals can be realized. Sending and receiving can also take place simultaneously. So sending and receiving run in parallel.

A further development includes one of the localization methods being radar-based child detection (CPD - child presence detection) and another of the localization methods being UWB-based radio key localization (UWB - ultra wide band, i.e. a bandwidth greater than 0.5 MHz, in particular more than 1 MHz). No compact circuit solution is known to date for this combination of localization methods. Transmission frequencies for the measurement cycles can be in a range from 1 GHz to 10 GHz. Radio signals from a radio key standard and/or radar standard can be used, to name just a few examples of the application area of the antenna device.

A further development includes the respective switching unit having at least one electrically controllable switching element, each of which comprises a transistor, in particular a GaAs transistor. A single transistor or a combination of transistors can therefore be provided as the switching unit. Using GaAs transistors has the additional advantage that high-frequency signals in a range of up to 10 gigahertz can be transmitted between the antenna connection and the signal port via the switching unit with low loss. Other transistors can be used, such as HEMTs (high electron mobility transistors). Diodes or MEMS can also be used as switches.

As a further solution, the invention comprises a method for operating an embodiment of the antenna device, wherein, in order to localize at least one object, electromagnetic radiation (radar or UWB) emanating from the object is received by means of several antennas and converted into a respective received signal. The method can be implemented in the manner described as program code of a microprocessor or microcontroller of the control circuit and/or as a logic gate and/or as an ASIC in the control circuit. It can be part of a chipset, which can also have the signal ports described. The chipset or the control circuit is thus connected, for example, on a circuit board to the antenna connections via switching units, wherein each switching unit connects or connects one of the signal ports to several of the antenna connections. By switching the switching state of the switching unit, one of the antenna connections is then electrically connected to the respective signal port. The setting of the switching states can be carried out in the manner described by a control signal of the control circuit itself, for example according to the control logic, so that depending on the active localization method, an associated switching state of the switching units is set and the switching states for the different measuring cycles are changed accordingly as specified.

Only some of the antennas are connected via a respective switching unit to another of several signal ports of a control circuit of the antenna circuit and according to a switching state of the switching unit, the reception signal of only one of the antennas is received by the respective signal port. The control circuit applies a predetermined localization method to the received signals, which includes connecting different antennas to the signal ports in successive measurement cycles by setting a respective switching state of the switching units and combining localization results generated from the different measurement cycles by applying the respective localization method. The expert can determine or control which localization method is currently active or is applied to the received signals as required. Since the switching states of the switching units can now also be changed within a localization method by changing between the measurement cycles, a localization method can also be carried out repeatedly on the basis of different antenna constellations and the localization results from the different measurement cycles can be combined. A localization method can also be implemented in such a way that different measuring principles, for example distance measurement and/or angle of incidence estimation, can be applied for the individual measuring cycles in order to determine, for example, the angle of incidence and the distance for the localization method or in localization methods by combining them.

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

For use cases or application situations that may arise during the method and which are not explicitly described here, it may be provided that, in accordance with the method, an error message and/or a request to enter user feedback is issued and/or a default setting and/or a predetermined initial state is set. As a further solution, the invention comprises a motor vehicle with an embodiment of the antenna device. The motor vehicle can be, for example, a passenger car or a truck.

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

An embodiment of the invention is described below. Shown here:

Fig. 1 is a schematic representation of an embodiment of the motor vehicle according to the invention, in which an embodiment of the antenna device according to the invention can be provided which carries out an embodiment of the method according to the invention;

Fig. 2 is a schematic representation of an antenna arrangement of antennas;

Fig. 3 is a sketch illustrating an embodiment of the method according to the invention with two measuring cycles of a localization method;

Fig. 4 is a schematic representation of the switching states of switching units for carrying out the method according to Fig. 3;

Fig. 5 is a sketch illustrating an embodiment of the method according to the invention with two measuring cycles for a localization method;

Fig. 6 is a schematic representation of switching states of the switching units for carrying out the method according to Fig. 5; Fig. 7 is a schematic representation of a second antenna arrangement as may be provided for the antenna device;

Fig. 8 is a sketch illustrating a method based on the second antenna arrangement;

Fig. 9 is a schematic representation of switching states of the switching units for carrying out the method according to Fig. 8;

Fig. 10 is a schematic representation of a third antenna arrangement of antennas as may be provided for the antenna device;

Fig. 11 is a sketch illustrating a method as can be provided by means of the third antenna arrangement for a localization method with at least two measuring cycles;

Fig. 12 is a schematic representation of switching states of the switching units for carrying out the method according to Fig. 11;

Fig. 13 is a schematic representation of variants of a linear antenna arrangement, wherein the variants differ with respect to the polarizations or the polarization orientation of the antennas;

Fig. 14 several variants of a rectangular or square or circular antenna arrangement, wherein the variants differ in the orientation of the polarizations of the antennas;

Fig. 15 several variants of an L-shaped antenna arrangement of antennas, wherein the variants differ with respect to the orientation of the polarizations of the antennas; Fig. 16 is a schematic representation of a T-shaped antenna arrangement of antennas, where the variants differ in terms of the orientation of the polarizations of the antennas.

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 that are to be considered independently of one another, which also develop the invention independently of one another and are therefore to be considered as part of the invention individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by other features of the invention that have already been described.

In the figures, functionally identical elements are provided with the same reference symbols.

Fig. 1 shows a motor vehicle 10, which can in particular be a road vehicle, for example a passenger car or truck. An antenna device 11 can be provided in the motor vehicle 10, which can be arranged, for example, on a roof or under a roof of the motor vehicle 10. The antenna device 11 can have antennas 12, in particular four antennas 12. To distinguish the antennas in the following text, they are distinguished from one another by serial numbers 1, 2, 3, 4. Radio signals 14 can be received from an external environment 13 of the motor vehicle 10 by means of the antennas 12 of the antenna device 11. Additionally or alternatively, an interior space in the vehicle can be covered or monitored.

The radio signals 14 converted into electrical signals by the antennas 12 can be passed to a control circuit 16 of the antenna device 11. In this case, the antenna signals of all antennas 12 are not forwarded, but only a selection of them is forwarded as a respective reception signal 17 to a signal input or signal port 18 of the control circuit 16. The Control circuit 16 can be implemented, for example, on a circuit board, for example on the basis of a chipset or an electronic circuit. To distinguish the signal ports 18, these are referred to below as Rx1, Rx2. A localization method L1, L2 can be carried out using the received signals 17. Several localization methods L1, L2 can be implemented, whereby one of the localization methods L1, L2 can be currently active. For example, a microprocessor or CPU20 (CPU - central processing unit) of the control circuit 16 can carry out the respective localization method L1, L2. A localization result 21 resulting from application of the respective localization method L1, L2 to the received signals 17 can be signaled in the motor vehicle 10 to a control unit 22, which can then output control commands 23 to at least one actuator 24 of the motor vehicle 10, for example a central locking system and/or an automated driving function, depending on the localization result 21.

The localization method L1 can, for example, provide for localization of an electrical device acting as a radio key 25, for example a radio key itself or a smartphone. The radio signal 14 received for this purpose by the radio key 25 can be a UWB signal in a manner known per se. The localization method L2 can, for example, provide for radar-based person detection, wherein for this purpose a transmission signal 26 can be emitted by means of the antenna device 11 via one of the antennas 12, which can be reflected by a person 27 and returned to the antennas 12 as a radio signal 14. The radio key 25 or the person 27 thus each represent an object 0 that is localized in the external environment 13. Localization in an interior of the motor vehicle 10 can also be provided by means of the antennas 12.

In order to be able to carry out the different localization methods L1, L2 and in order to be able to form, in particular or alternatively, within or for the respective localization method L1, L2, different antenna constellations formed from the antennas 12 can be formed, the active antennas 12 of which In order to provide the received signal 17 at the signal ports 18, the signal ports 18 can be connected to the antennas 12 via switching units 30, which can also be arranged on the circuit board or a circuit board of the control circuit 16, for example. The signal ports 18 can be connected to respective antenna connections 31 via the switching units 30, wherein one of the antennas 12 can be connected to each antenna connection 31. The antennas 12 can also be implemented on the circuit board PCB for this purpose, for example as a monopole antenna, dipole antenna, patch antenna or slot antenna, or they can be electrically connected to the antenna connections 31 as separate components, for example via a coaxial cable.

When carrying out one of the localization methods L1, L2, several measuring cycles C1, C2 can be provided, which can be carried out one after the other. Fig. 1 shows how a different switching state 32 can be set for the different measuring cycles C1, C2 in the respective switching unit 30, which is symbolized by a solid or dashed line. The switching unit 30 can have at least one switching element 33, for example at least one transistor, for setting the respective switching state 32. The lines symbolize which of the antenna connections 31 is electrically connected to the assigned or connected signal port 18 in the respective switching state 32.

The switching states 32 can be controlled by means of a switching signal 34 by the control circuit 16, for example its microprocessor or CPU 20. The switching units 30 are distinguished from one another below by the designation S-Rx1, S-Rx2 (S stands for switch).

Fig. 2 illustrates a possible structural arrangement of the antennas 12, which can be provided here as an equidistant, for example linear antenna array. A grid spacing d, i.e. an antenna spacing d, between adjacent antennas can be less than or equal to half the wavelength X, i.e. d < A/2. The antenna arrangement shown in Fig. 2 is referred to as antenna arrangement I in the following.

Fig. 3 illustrates how, in the method for carrying out one of the localization methods or both localization methods L1, L2, a first antenna combination or sequence of antenna combinations l-l can be carried out by setting the illustrated switching states for two consecutive switching cycles C1, C2.

Fig. 4 illustrates the corresponding switching states for the two measuring cycles C1, C2.

Fig. 5 illustrates an antenna combination I-III for the antenna arrangement I.

Fig. 6 illustrates the corresponding switching states for the two measuring cycles C1, C2, as they can be provided in the two switching units S-Rx1, S-Rx2.

Fig. 7 illustrates a second antenna arrangement II, in which in a linear antenna array with four antennas 12 the inner antennas 2, 3 have an antenna spacing d which is less than or equal to half the wavelength X and the outer antennas 1, 4 have at least a distance D>d from the inner antennas 2, 3, so that the antennas 1, 4 have a distance D greater than half the wavelength from the next antenna in an antenna-free space 50.

Fig. 8 illustrates an antenna combination II-III based on the antenna arrangement II, as it can be adjusted for two measuring cycles C1, C2 for one or both localization methods.

Fig. 9 illustrates the corresponding switching states of the switching elements S-Rx1, S-Rx2 for the switching cycles C1, C2 for the method according to Fig. 8. Fig. 10 illustrates a third antenna arrangement III, in which of the antennas 12 in a linear array the two outer antennas 1, 2 and 3, 4 have an antenna spacing d less than or equal to half the wavelength of the reception frequency used and between these two antenna pairs 52 in an antenna-free space 50 an antenna spacing D > d and in particular greater than half the wavelength of the signal frequency is provided.

Fig. 11 illustrates how, on the basis of this antenna arrangement III in a first antenna combination III-I, the received signals can be routed to the signal ports Rx1, Rx2 in two measuring cycles C1, C2.

Fig. 12 illustrates corresponding switching states of the switching units S-Rx1, S-Rx2 for two measuring cycles C1, C2.

Fig. 13 illustrates that in the respective antenna arrangement, the antennas 12 can also be arranged with specifically set polarization orientations, with an upward arrow symbolizing a vertical orientation (0 degrees), a horizontal arrow a horizontal orientation (90 degrees) and an oblique arrow an orientation at 45 degrees of polarization with respect to the vertical. It is shown how, for different variants P1.1 to P1.5, the antennas 12 can have different relative or absolute orientations in their polarization.

Fig. 14 illustrates the principle of Fig. 13 for an antenna array with antennas 12 arranged in a rectangle or square or circle.

Fig. 15 illustrates the principle of Fig. 13 for an antenna array with an L-shape arrangement of the antennas 12.

Fig. 16 illustrates the principle of Fig. 13 for an antenna array in which the antennas 12 are arranged in a T-shape. The arrangements according to Fig. 13 to Fig. 16 and additionally or alternatively also further arrangements can be electrically connected alternately to the signal ports 18 by means of the switching units 30 for carrying out localization methods such as the localization methods L1, L2 in different measuring cycles and/or for different localization methods in order to provide or use the respective received signal 17 (see Fig. 1) as an input signal for the respective localization method or the current measuring cycle. The person skilled in the art can choose here which received signal 17 is advantageous for a respective measuring cycle for generating a localization result 21 (see Fig. 1).

The idea deals with the combination of antenna switching concepts that cover the new localization functions CPD (Child Presence Detection) and AoA (Angle of Arrival) on UWB technology with little hardware effort, especially on circuit boards with a size that provides edge lengths of less than 20 cm. Until now, the combination of both functions (CPD and AoA) has not yet been integrated in a UWB transceiver. The integration of both functions is achieved here with an antenna switching concept in order to provide both functions in a UWB transceiver.

Such a UWB transceiver, which combines both CPD & AoA functions, was not previously state of the art. Only the UWB chipset (control circuit) presented here can offer the possibility of integrating both functions on a UWB transceiver. The concept of antenna switching makes it possible to implement the CPD and AoA functions in a UWB transceiver and ensures the required antenna performance for each of the localization functions.

The antenna switching concept allows to use the Tx/Rx ports of the chipset depending on the function used (CPD or AoA) to benefit from the required/needed antenna performance for each function. Both functions require coherent UWB signal Tx and Rx capability of the antennas, which is enabled by our switch concept with minimal hardware. The details are as follows.

Detailed switching concept:

For the AoA function, antennas 1+2 or 3+4 can be combined for one AoA cycle. That is, for the first Rx cycle, antenna 1+2 is used (one of them also for Tx), and for the second Rx cycle, antenna 3+4 is used (one of them also for Tx). For the CPD function, antennas 2+3 and 1+4 can be combined for one CPD cycle. That means that for the Rx cycle, antennas 2+3 are used, and for diversity purposes, antennas 1+4 can be used for another Rx cycle. The current chipset allows AoA or CPD cycles to transmit on one Tx/Rx port and receive on 2 Tx/Rx ports simultaneously. This allows the following cycle combinations for - AoA: o Cycle 1 : Antenna 1 or antenna 2 transmits, antennas 1 +2 receive o Cycle 2: Antenna 3 or antenna 4 transmits, antennas 3+4 receive - CPD: o Cycle: Antenna 2 or antenna 3 transmits, antennas 2+3 receive o Diversity purposes: Antenna 1 or antenna 4 transmits, antennas 1 +4 receive

Use for AoA functionality:

The ability of an antenna system to estimate AoA requires that the antenna can transmit a UWB signal to the environment and that an antenna pair can receive a UWB signal that is coherent with each other and with the UWB Tx signal. The Rx signal can either be derived from reflections of the UWB signal we have transmitted from a person/object, or it can be an active UWB signal generated and transmitted by an active counterpart that we have initialized and synchronized with our UWB Tx signal.

The framework for AoA estimation then uses the Rx signal characteristics on the coherent Rx antenna pairs, then a signal processor result is available, which is enabled by the hardware we propose. A typical planar coverage for an AoA system consists of angles between 0°-180° (semicircle). Accordingly, a typical AoA hardware concept has the following problems: - The antennas used have a limited field of view (FoV) within the AoA estimation angle. - The antenna pairs for transmit/receive must provide similar performance in terms of polarization and field of view and ensure good isolation between them. Our system offers the following contributions: - In our switch concept, we propose a Tx diversity (contribution) since we can transmit the UWB signal from any of the antenna elements, which improves the FoV. - For the Rx antenna, AoA estimation requires a specific pair of Rx antennas in terms of FoV and polarization. Without increasing the number of Rx ports (contribution), with our switch concept we enable diversity of AoA estimation with an extended FoV and diversity of polarization.

In short, a compact AoA estimation hardware with only 2 coherent Rx ports is proposed, which has higher performance due to diversity.

Distance detection

- For distance measurement, both antennas of a sensor receive the signal sent by another device (e.g. key, smartphone, ...) per distance measurement cycle. The received signals represent the channel impulse responses (CIRs) between the transmitter and the two receivers of a sensor. - The distance to the transmitter can be estimated from the received CIRs. During a measurement cycle, one distance estimate is made per signal, ie 2 estimates per cycle.

- With 2 measurement cycles, 2 pairs of Rx antennas can be used, i.e. 4 estimates are obtained.

- In the example below, 4 cycles with 4 alternating antenna combinations can be used: o Cycle 1 : Antenna 1 + 2 o Cycle 2: Antenna 3 + 4 o Cycle 3: Antenna 1 + 4 o Cycle 4: Antenna 2 + 3

This means that a total of 8 CIRs are determined.

- Fusion of range estimates between multiple cycles and antenna combinations allows for a reduction in estimation errors.

- In addition, the CIRs can be combined to achieve maximum signal-to-noise ratio (SNR) and AoA estimation, further improving range estimation.

Using the RADAR function

- With the RADAR function, one antenna of the sensor sends and receives (Tx/Rx) per measuring cycle and another antenna only receives (Rx). - The received signals represent reflections that occur on obstacles in the sensor's environment. The obstacles are illuminated by the transmitted signal and reflect part of the signal back to the sensor. The reflections from multiple obstacles and multiple propagation paths constitute the channel impulse response (CIR). In addition to the case where one sensor transmits a signal and the same sensor receives the signal (monostatic RADAR), there can also be at least two sensors, one transmitting and the other receiving, or one transmitting and receiving and the other receiving only in one measurement cycle (multistatic RADAR). - Depending on the Tx/Rx antenna and Rx antenna chosen, several CIRs can be obtained. See for example the figure below. The following scheme can be applied: o Cycle 1 : antenna 1 does Rx, antenna 2 does Tx/Rx o Cycle 2 : antenna 3 does Tx/Rx, antenna 4 does Rx

This means that 2 CIRs are achieved per cycle, for a total of 4 CIRs.

This scheme includes Tx and Rx diversity, even if only a portion of the diversity manifold is used.

- Let us consider another example based on the embodiment shown in the following figure: o Cycle 1 : Antenna 1 does Tx/Rx, Antenna 2 does Rx o Cycle 2: Antenna 1 does Tx/Rx, Antenna 4 does Rx o Cycle 3: Antenna 1 does Rx, Antenna 2 does Tx/Rx o Cycle 4: Antenna 2 transmits/receives, Antenna 3 transmits o Cycle 5: Antenna 2 does Rx, antenna 3 does Tx/Rx o Cycle 6: Antenna 3 sends/receives, antenna 4 sends o Cycle 7: Antenna 1 does Rx, antenna 4 does Tx/Rx o Cycle 8: Antenna 3 does Rx, antenna 4 does Tx/Rx

This means that 2 CIRs are determined per cycle, for a total of 16 CIRs.

The full set of Tx and Rx diversity schemes is used, as every antenna is used for transmitting and every possible pair of antennas is used for receiving. In a multistatic setup, more combinations are possible, as a larger diversity spectrum can be used.

The antenna switching concept allows to choose the best antenna performance for each function, as Tx and Rx diversity are available for ranging/RADAR functions, in such a way that both functions are combined in a UWB transceiver design with only 2 Rx ports and the required PCB space is reduced to a minimum.

One embodiment consists of 2 switches. One switch is used to select antenna 1 or 3, the other switch to select antenna 2 or 4. In a first measurement cycle "cycle 1", antennas 1 and 2 are active and the signal received by these antennas is forwarded to the receiver branches Rx1 and Rx2. In a second measurement cycle "cycle 2", antennas 3 and 4 are active and the signal received by these antennas is forwarded to the receiver branches Rx1 and Rx2.

Overall, the example shows how a combined antenna concept for radar-based person detection as a first localization method and a Radio key localization can be provided as a second localization method.

List of reference symbols

10 Motor vehicle

11 Antenna device

12 antennas

13 Outdoor environment

13 Environment

14 Radio signal

16 Control circuit

17 Reception signal

18 Signal port

20 processor

21 Localization result

22 Control unit

23 control commands

24 Actuator

25 radio keys

26 Transmission signal

27 people

30 Switching unit

31 Antenna connection

32 Switching state

33 Switching element

34 Switching signal

50 gap

52 antenna pairs

Claims

Patent claims

1. Antenna device (11) having four or more than four antenna connections (31) for connecting a respective antenna and having a control circuit (16) having two or more than two signal ports (18), characterized in that each of the signal ports (18) is connected to two or more than two of the antenna connections (31) via a respective switching unit (30), wherein the respective switching unit (30) is designed to assume one of several predetermined switching states (32) depending on a control signal, in which it keeps the signal port (18) connected to it electrically connected to another of the antenna connections connected to it, wherein the control circuit (16) is connected to a respective control input of the switching directions and the control circuit (16) has a control logic which, when Execution by the control circuit (16) causes the latter to generate the control signal and to apply one or alternately at least two different predetermined localization methods to reception signals (17) received via the signal ports for respectively localizing at least one object.

2. Antenna device (11) according to claim 1, wherein each of the switching units (30) is connected to other ones of the antennas (12).

3. Antenna device (11) according to one of the preceding claims, wherein one or more or each localization method provides different switching states (32) of the switching units (30) for different successive measuring cycles.

4. Antenna device (11) according to one of the preceding claims, wherein one or more or each localization method for localizing the at least one object comprises a phase-based angle of incidence estimation, AoA, by means of the received signals (17) directed to the signal ports (18).

5. Antenna device (11) according to claim 4, wherein one or more or each localization method comprises comprising at least two measurement cycles, both of which comprise the angle of incidence estimation, wherein in the measurement cycles different ones of the antenna ports (31) are connected to the signal ports (18).

6. Antenna device (11) according to one of the preceding claims, wherein one or more or each localization method for localizing the at least one object comprises a runtime-based distance measurement carried out on the signals conducted to the signal ports (18).

7. Antenna device (11) according to claim 6, when dependent on claim 5 or 4, wherein one or more or each localization method each comprises comprising at least two measurement cycles, one of which comprises the angle of incidence estimation and one of which comprises the time-of-flight based measurement.

8. Antenna device (11) according to one of the preceding claims, wherein in each case an antenna is electrically connected to one of the antenna connections (31) and one or more or each localization method in each case comprises that it comprises at least two measuring cycles, of which in one of the measuring cycles the signal ports (18) are connected to those of the antennas (12) whose distance is less than or equal to half a wavelength of a transmission frequency of a transmission circuit of the antenna device (11) used in the measuring cycle and in another of the measuring cycles the signal ports (18) are connected to those of the antennas (12) whose distance is greater than half a wavelength of a transmission frequency of the transmission circuit used in the measuring cycle, wherein the localization method comprises generating an ambiguous localization result (21) in the measuring cycle with the distance greater than half the wavelength and making the localization result (21) unambiguous in the measuring cycle with the distance less than or equal to half the wavelength.

9. Antenna device (11) according to claim 8, wherein the antennas (12) are arranged to form an antenna array in which the antennas (12) are arranged equidistantly with a grid spacing less than or equal to half the wavelength or only two or only some of the antennas (12) are arranged at a spacing less than or equal to half the wavelength of the transmission frequency and two or some of the antennas (12) are arranged at a spacing greater than half the wavelength from at least one other of the antennas (12) across an antenna-free gap (50).

10. Antenna device (11) according to one of the preceding claims, wherein at least one of the signal ports (18) is additionally designed as a transmit and receive port which, in order to generate the receive signals (17), generates a transmit signal (26) for radiating via the currently electrically connected antenna and then receives one of the receive signals (17) in a receive mode.

11. Antenna device (11) according to one of the preceding claims, wherein one of the localization methods is a radar-based child detection and another of the localization methods is a UWB-based radio key localization of a radio key (25) or a device acting as a radio key.

12. Antenna device (11) according to one of the preceding claims, wherein the respective switching unit (30) has at least one electrically controllable switching element (33), each comprising a transistor.

13. Method for operating an antenna device (11) according to one of the preceding claims, wherein, in order to localize at least one object, electromagnetic radiation emanating from the object is received by means of a plurality of antennas (12) and converted into a respective reception signal (17), wherein some of the antennas (12) are connected via a switching unit (30) to another signal port of a chipset of the antenna circuit and, according to a switching state (32) of the switching unit (30), the reception signal (17) of only one of the antennas (12) is transmitted through the signal port (18) is received, wherein a predetermined localization method is applied to the received reception signals (17), which comprises that in successive measuring cycles by setting a respective switching state (32) of the switching units (30) different ones of the antennas (12) are connected to the signal ports (18) and by applying the respective

Localization results (21) generated by the localization procedure from the different measurement cycles are combined.

14. Motor vehicle (10) with an antenna device (11) according to one of claims 1 to 12.