Antenna device

Abstract

The invention relates to an antenna device (10a; 10b), in particular an NFC antenna device, having at least two electric conductors (12a, 14a; 12b, 14b) for connecting to an antenna (16a). To improve efficiency, it is proposed that the electric conductors (12a, 14a; 12b, 14b) are embedded in a carrier element (18a) of electrically insulating material and perpendicular to their main direction of extension (20a; 20b) have a predefined minimum distance (22a; 22b) from each other of at least 2 mm.

Description

[0001] Antenna device

[0002] The invention relates to an antenna device according to the preamble of claim 1, an induction energy transmission system with an antenna device according to claim 9 and a method for producing an antenna device according to the preamble of claim 11.

[0003] Antenna devices with at least two electrical conductors for connection to an antenna are already known from the prior art. For example, the electrical conductors can be part of a coaxial cable, wherein the electrical conductors within the coaxial cable are separated from each other by a cylindrical dielectric insulator to reduce electromagnetic interference, such as stray capacitances and / or stray inductances between the electrical conductors. For many applications, the use of coaxial cables is difficult to implement economically due to their comparatively high costs, thus adversely reducing efficiency, particularly cost-effectiveness.For some applications, particularly for induction energy transmission systems which, in addition to heating cookware, are also designed for the inductive energy supply of small household appliances, such as kitchen appliances and the like, and which have a communication unit for wireless communication, for example via NFC, the use of coaxial cables is not easily possible anyway due to the high heat development, so that a high-temperature circuit board has to be used for this purpose, which is directly connected to the antenna and arranged in the high-temperature area, which also entails high costs and reduced efficiency.

[0004] The object of the invention is, in particular but not limited to, to provide a generic device with improved properties in terms of efficiency. This object is achieved according to the invention by the features of claims 1 and 11, while advantageous embodiments and further developments of the invention can be found in the subclaims. The invention is based on an antenna device, in particular an NFC antenna device, with at least two electrical conductors for connection to an antenna.

[0005] It is proposed that the electrical conductors are embedded in a carrier element made of an electrically insulating material and have a predefined minimum distance of at least 2 mm from each other perpendicular to their main direction of extension.

[0006] Such a configuration advantageously provides an antenna device with improved efficiency properties. Cost efficiency can advantageously be increased. Firstly, manufacturing costs can be reduced compared to the previously required use of shielded cables, such as coaxial cables, for connecting to an antenna. Furthermore, a high-temperature circuit board and a high-temperature and high-frequency connector for operating the antenna in applications within induction energy transmission systems can advantageously be dispensed with, since a normal circuit board for a communication unit of the induction energy transmission system can now advantageously be arranged outside a high-temperature region and connected to the antenna in the high-temperature region by means of the antenna device.At the same time, it is advantageously possible to integrate an antenna with an enameled copper winding that can withstand the high temperatures of an induction coil. Furthermore, interference, such as stray capacitance between the electrical conductors, can be advantageously reduced if the electrical conductors have a predefined minimum distance of at least 2 mm from each other perpendicular to their main direction of extension.

[0007] The antenna device can be designed as a component, in particular as a structural and / or functional component, of an antenna or as an accessory for an antenna. The antenna device can comprise the antenna. The antenna is provided for emitting and receiving electromagnetic waves for wireless communication. The antenna can be provided for wireless communication via RFID, or via WIFI, or via Bluetooth, or via ZigBee, or for wireless communication according to another suitable standard for wireless communication. Preferably, the antenna is provided for wireless communication via NFC, wherein the antenna device is then designed as an NFC antenna device.

[0008] The antenna device has at least two electrical conductors for connection to the antenna and may further comprise further electrical conductors for connection to the antenna and / or another antenna. The electrical conductors are formed from an electrically conductive material, for example, copper. The electrical conductors are embedded in the carrier element made of an electrically insulating material. The carrier element may be formed, for example, from a plastic, for example, silicone and / or a plastic from the polyimide group, or from a ceramic, for example, aluminum oxide ceramic, or from another electrically insulating material, without being limited thereto.

[0009] The electrical conductors are embedded in the carrier element made of electrically insulating material and, perpendicular to their main direction of extension, have a predefined minimum spacing of at least 2 mm from one another. Perpendicular to their main direction of extension, the electrical conductors may also have a spacing greater than the predefined minimum spacing from one another than the predefined minimum, for example, at least 3 mm, in particular at least 4 mm, advantageously at least 5 mm, particularly advantageously at least 6 mm, preferably at least 7 mm, preferably at least 8 mm, and particularly preferably at least 9 mm. A "main direction of extension" of an object is understood to mean a direction that runs parallel to a longest edge of a smallest geometric cuboid that just completely encloses the object.

[0010] The antenna device can be part of an induction energy transmission system. The induction energy transmission system has at least one main functionality in the form of wireless energy transmission, in particular in a wireless energy supply to installation units, and for this purpose comprises at least one induction device. In an advantageous embodiment, the induction energy transmission system is designed as an induction cooking system with at least one additional main function that differs from a pure cooking function, in particular at least a power supply and operation of small household appliances. For example, the induction energy transmission system could be designed as an induction oven system and / or as an induction grill system.Preferably, the induction energy transmission system configured as an induction cooking system is configured as an induction hob system, wherein at least one induction device of the induction energy transmission system is configured as an induction hob. In a further advantageous embodiment, the induction energy transmission system is configured as a kitchen energy supply system and, in addition to a primary function in the form of energy supply and operation of installation units, can also be provided for providing cooking functions, wherein at least one induction device of the kitchen energy supply system is configured as an induction energy supply device.

[0011] The induction energy transmission system preferably comprises at least one support plate for supporting at least one support unit, the support plate preferably being part of the induction appliance. A "support plate" is to be understood as at least one, in particular plate-like, unit of the induction energy transmission system, which is provided for supporting at least one support unit and / or for placing at least one item of food on it. The support plate could, for example, be designed as a worktop, in particular as a kitchen worktop, or as a partial region of at least one worktop, in particular at least one kitchen worktop, in particular of the induction energy transmission system. Alternatively or additionally, the support plate could be designed as a hob plate.The installation plate designed as a hob plate could, in particular, form at least part of a hob outer housing and, in particular, together with at least one outer housing unit, to which the installation plate designed as a hob plate could, in particular, be connected in at least one assembled state, form at least a large part of the hob outer housing. The installation plate is preferably made of a non-metallic material. The installation plate could, for example, be formed at least largely from glass and / or glass ceramic and / or Neolith and / or Dekton and / or wood and / or marble and / or stone, in particular natural stone, and / or laminate and / or plastic and / or ceramic.In this document, location designations such as "below" or "above" refer to the installed state of the mounting plate, unless explicitly stated otherwise. In the installed state, the supply unit is preferably located below the mounting plate.

[0012] The induction energy transmission system preferably comprises at least one supply unit, which is part of the induction device and comprises at least one inductor for inductively supplying energy to at least one installation unit. The supply unit inductively provides energy in at least one operating state and, in particular, has a main functionality in the form of inductive energy provision. For the inductive provision of energy, the supply unit has the at least one inductor, which in particular has at least one coil, in particular at least one primary coil, and / or is designed as a coil, and which, in particular, provides energy inductively in the operating state.The supply unit could have at least two, in particular at least three, advantageously at least four, particularly advantageously at least five, preferably at least eight, and particularly preferably a plurality of inductors, each of which could inductively provide energy in the operating state, in particular to a single installation unit or to at least two or more installation units. At least some of the inductors could be arranged in close proximity to one another, for example, in a row and / or in the form of a matrix.

[0013] The induction energy transmission system preferably comprises a control unit, which is designed as an electronic unit and is intended to control and / or regulate at least the supply unit. The control unit comprises a computing unit and, in particular, in addition to the computing unit, a memory unit with at least one control and / or regulating program stored therein, which is intended to be executed by the computing unit. The control unit advantageously has at least one inverter unit. In the operating state, the inverter unit preferably performs a frequency conversion and, in particular, converts a low-frequency AC voltage on the input side into a high-frequency AC voltage on the output side. The low-frequency AC voltage preferably has a frequency of at most 100 Hz.

[0014] The high-frequency alternating voltage preferably has a frequency of at least 1000 Hz. The inverter unit is preferably designed to adjust the energy provided inductively by the at least one inductor by adjusting the high-frequency alternating voltage. The control unit preferably comprises at least one rectifier. The inverter unit has at least one inverter with at least one, preferably at least two, inverter switching element(s). The inverter switching element preferably generates an oscillating electrical current, preferably with a frequency of at least 15 kHz, in particular of at least 17 kHz, and advantageously of at least 20 kHz, for operating the at least one supply induction element.The inverter unit preferably comprises at least two inverter switching elements, which are preferably designed as insulated gate bipolar transistors (IGBT) and particularly advantageously at least one damping capacitor.

[0015] The induction energy transmission system preferably comprises at least one installation unit. A "installation unit" is understood to mean a unit which, in at least one operating state, receives energy inductively and at least partially converts the inductively received energy into at least one further form of energy to provide at least one main function. For example, the energy received inductively by the installation unit could be converted, in particular directly, into at least one further form of energy, such as heat, in the operating state. Alternatively or additionally, the installation unit could have at least one electrical consumer, for example an electric motor or the like. The installation unit has at least one receiving unit with a receiving inductor for receiving the inductively provided energy.The receiving unit could, for example, have at least two, in particular at least three, advantageously at least four, particularly advantageously at least five, preferably at least eight, and particularly preferably a plurality of receiving inductors, which could each inductively receive energy, particularly from the inductor of the supply unit, particularly in the operating state. The installation unit could, for example, be designed as a cooking utensil. The cooking utensil preferably has at least one food receiving space and, in the operating state, converts the inductively received energy at least partially into heat for heating food arranged in the food receiving space.Preferably, the installation unit designed as a cooking utensil has at least one further unit for providing at least one further function that goes beyond and / or differs from simply heating food. For example, the further unit could be designed as a temperature sensor or as a stirring unit or the like. Alternatively, the installation unit could be designed as a small household appliance. Preferably, the small household appliance is a location-independent household appliance that has at least the receiving induction element and at least one functional unit that provides at least one household appliance function in an operating state.In this context, "location-independent" means that the small household appliance can be positioned freely within a household by a user, in particular without any tools, particularly in contrast to a large household appliance, which is permanently positioned and / or installed at a specific location within a household, such as an oven or a refrigerator. Preferably, the small household appliance is designed as a small kitchen appliance and, in its operating state, provides at least one main function for processing food.The small household appliance could, for example, be designed as, but not limited to, a food processor and / or as a blender and / or as a stirrer and / or as a grinder and / or as a kitchen scale or as a kettle or as a coffee maker or as a rice cooker or as a milk frother or as a deep fryer or as a toaster or as a juicer or as a cutting machine or the like.

[0016] The induction energy transmission system advantageously comprises at least one communication unit for wireless communication between the control unit and at least one installation unit. The communication unit is preferably provided for bidirectional wireless data transmission, i.e., for both wireless reception and wireless transmission of data between the control unit and the installation unit. The communication unit preferably has at least one communication element connected to the control unit and, in particular, provided for wireless reception and transmission of data. The communication unit preferably has at least one further communication element arranged within the installation unit and, in particular, provided for wireless reception and transmission of data.The communication unit could be provided for wireless data transmission between the installation unit and the control unit via RFID, WIFI, Bluetooth, ZigBee, or for wireless data transmission according to another suitable standard. Preferably, the communication unit is provided for wireless data transmission between the installation unit and the control unit via NFC. Preferably, the antenna device is part of the communication unit of the induction energy transmission system. For example, a first antenna device of the induction energy transmission system can be assigned to the communication element connected to the control unit and can be provided to establish a connection between the communication element and the antenna. The induction energy transmission system can also comprise multiple antenna devices.For example, the induction energy transmission system may comprise a further antenna device which is integrated in the installation unit and is intended to establish a connection between the further communication element and an antenna of the installation unit.

[0017] In this document, numerals such as "first" and "second," which precede certain terms, serve only to distinguish between objects and / or to correlate objects with each other and do not imply a total number and / or ranking of the objects. In particular, a "second object" does not necessarily imply the presence of a "first object."

[0018] "Intended" should be understood as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood as meaning that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0019] It is further proposed that the support element be made of mica. This advantageously further improves efficiency. In addition to electrical insulation of the electrical conductors from the environment, improved dissipation of waste heat can also be achieved if the support element is made of mica.

[0020] It is also proposed that the carrier element be flat. This advantageously enables a particularly compact design of the antenna device. The term "flat" for the carrier element should be understood to mean that the carrier element has a maximum width extending perpendicular to a length, which is at least a factor of 10 greater than a maximum depth extending perpendicular to the length. The carrier element is designed differently from a cable sheath and a cable insulation.

[0021] The antenna device could have at least one connection element, for example a plug or the like, which is provided for establishing the connection between the electrical conductors and the antenna. In an advantageous embodiment, however, it is proposed that the antenna device has the antenna which is formed integrally with the electrical conductors. Such a configuration can advantageously further improve efficiency. In particular, material efficiency can be improved and manufacturing costs reduced. “Integral” should be understood to mean at least materially connected, for example by a welding process, a soldering process or another process that appears appropriate to a person skilled in the art, and / or advantageously formed from a single piece. The electrical conductors are preferably formed integrally with the antenna.For example, the antenna and the electrical conductors may be formed from a single piece of a single wire made of an electrically conductive material, such as a copper wire.

[0022] Furthermore, it is proposed that a capacitive coupling exist between the electrical conductors in a current-carrying state, which causes a specific stray capacitance of at most 0.08 pF / cm based on a length of the electrical conductors. This can advantageously reduce interference with wireless communication. In particular, it can be achieved that the total capacitance of the antenna device with the antenna can be kept below a desired maximum value. For example, the antenna can be designed as an NFC antenna and, in accordance with the NFC standard, can be intended for operation at a communication frequency of 13.56 MHz, wherein a natural resonant frequency should be at least 25.0 MHz to ensure interference-free communication. To achieve a natural resonant frequency of at least 25.0 MHz, the total capacitance of the antenna with the antenna device may not exceed 13 pF.If a capacitive coupling exists between the electrical conductors in a current-carrying state, which causes a specific stray capacitance of at most 0.08 pF / cm relative to a length of the electrical conductors, an influence of the stray capacitance on the total capacitance of the antenna with the antenna device can be minimized and thus a natural resonant frequency of at least 25.0 MHz can be easily achieved even with longer electrical conductors of the antenna device.

[0023] Furthermore, it is proposed that an inductive coupling exist between the electrical conductors in a current-carrying state, which results in a specific stray inductance of at most 13.7 nH / cm relative to a length of the electrical conductors. This advantageously allows interference with wireless communication to be further reduced. In particular, it can be achieved that the total inductance of the antenna device with the antenna can be kept below a desired maximum value. To achieve a desired natural resonant frequency of at least 25.0 MHz in the case of an NFC antenna, the total inductance of the antenna with the antenna device may not exceed 3 pH.If an inductive coupling exists between the electrical conductors in a current-carrying state, which causes a specific leakage inductance of at most 13.7 nH / cm relative to a length of the electrical conductors, an influence of the leakage inductance on the total inductance of the antenna with the antenna device can be reduced and thus a natural resonant frequency of at least 25.0 MHz can be easily achieved even with longer electrical conductors of the antenna device.

[0024] In an advantageous embodiment, it is proposed that the electrical conductors be geometrically aligned parallel to one another at the predefined minimum distance. This advantageously enables a particularly compact design of the antenna device.

[0025] In an alternative advantageous embodiment, it is proposed that the electrical conductors be spirally shaped and have at least the predefined minimum distance from one another everywhere. Such a configuration can advantageously further reduce interference with wireless communication. In particular, a stray inductance of an inductive coupling between the electrical conductors in a current-carrying state can be further reduced. Preferably, an inductive coupling exists between the spirally shaped electrical conductors, which are arranged everywhere at least at the predefined minimum distance from one another, in a current-carrying state, which results in a specific stray inductance of at most 4.6 nH / cm based on a length of the electrical conductors.

[0026] The invention further relates to an induction energy transmission system having at least one antenna device according to one of the previously described embodiments. Such an induction energy transmission system is characterized in particular by its advantageous properties with regard to efficiency, which can be achieved by means of the antenna device.

[0027] It is also proposed that the induction energy transmission system comprise an induction device with a mounting plate, with at least one inductor arranged beneath the mounting plate, and with at least one insulating element arranged between the inductor and the mounting plate, wherein the insulating element functions as the support element for the electrical conductors of the antenna device. Such a configuration can advantageously further improve the efficiency of the induction energy transmission system. In particular, material and manufacturing costs can be reduced if the insulating element, which is already present in induction devices, for example induction cooktops, to dissipate heat loss from the inductor occurring during operation, simultaneously functions as the support element for the electrical conductors of the antenna device. The insulating element is preferably designed as a mica disc.

[0028] The invention further relates to a method for producing an antenna device, in particular according to one of the previously described embodiments, with at least two electrical conductors for connection to an antenna.

[0029] It is proposed that the electrical conductors are embedded in a support element made of an electrically insulating material and arranged perpendicular to their

[0030] The antenna elements are arranged at a predefined minimum distance of at least 2 mm from one another in the main direction of extension. Such a method can advantageously enable particularly efficient production of the antenna device.

[0031] The antenna device and the induction energy transmission system are not intended to be limited to the applications and embodiments described above. In particular, the antenna device and / or the induction energy transmission system may have a number of individual elements, components, and units that differs from the number stated herein to fulfill a functionality described herein.

[0032] Further advantages will become apparent from the following description of the drawings. The drawings illustrate two exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0033] They show:

[0034] Fig. 1 shows an induction energy transmission system with an induction device, with two mounting units and with an antenna device in a schematic perspective view,

[0035] Fig. 2 shows an insulation layer of the induction device and the antenna device with an antenna in a schematic representation,

[0036] Fig. 3 is a schematic representation of the antenna device with two electrical conductors for connection to the antenna and with a support element,

[0037] Fig. 4 two schematic diagrams of the antenna with the electrical conductors,

[0038] Fig. 5 two schematic diagrams illustrating stray inductances and stray capacitances between two electrical conductors in a configuration not according to the invention,

[0039] Fig. 6 is a schematic diagram showing stray inductances between the electrical conductors of the antenna device,

[0040] Fig. 7 is a schematic process flow diagram illustrating a method for producing the antenna device, and Fig. 8 is a schematic representation of another embodiment of an antenna device.

[0041] Figure 1 shows a schematic representation of an induction energy transmission system 26a. The induction energy transmission system 26a comprises an induction device 28a. The induction device 28a has a mounting plate 30a, at least one inductor 32a arranged below the mounting plate 30a, and at least one insulation element 34a arranged between the inductor 32a and the mounting plate 30a (see Figure 2). In the present case, the induction device 28a has a total of four inductors 32a.

[0042] In this case, the induction appliance 28a is designed as an induction hob. The mounting plate 30a is designed as a hob plate of the induction hob.

[0043] The induction energy transmission system 26a in this case has two mounting units 36a, 38a for mounting on the mounting plate 30a. One mounting unit 36a is designed as a food processor. Another mounting unit 38a is designed as a kettle. The mounting unit 36a has a receiving inductor 40a, which is provided for receiving energy inductively provided by one of the inductors 32a of the induction device 28a. The further mounting unit 38a also has a receiving inductor (not shown) for receiving energy inductively provided by one of the inductors 32a of the induction device 28a.

[0044] The induction energy transmission system 26a has a communication unit 42a. The communication unit 42a is provided for wireless communication between a control unit 44a of the induction device 28a and the mounting unit 36a and the additional mounting unit 38a. The communication unit 42a has a communication element 46a connected to the control unit 44a. The communication unit 42a has a further communication element 48a arranged in the mounting unit 36a. The communication unit 42a also has a further communication element 50a arranged in the additional mounting unit 38a. In the present case, the communication unit 42a is provided for wireless communication according to the NFC standard.

[0045] The induction energy transmission system 26a has at least one

[0046] Antenna device 10a. In this case, the antenna device 10a is part of the communication unit 42a and is connected to the communication element 46a. The antenna device 10a is embodied as an NFC antenna device.

[0047] Figure 2 shows the antenna device 10a and the insulation element 34a of the induction device 28a in a schematic representation. The antenna device 10a has at least two, in this case exactly two, electrical conductors 12a, 14a. The electrical conductors 12a, 14a are provided for connection to an antenna 16a. In this case, the antenna 16a is part of the antenna device 10a and is formed integrally with the electrical conductors 12a, 14a.

[0048] The antenna device 10a has a support element 18a. The support element 18a is made of an electrically insulating material. In the present case, the support element 18a is made of mica. The support element 18a has a flat design.

[0049] The electrical conductors 12a, 14a are embedded in the support element 18a. In this case, the insulating element 34a also functions as the support element 18a of the antenna device 10a.

[0050] Figure 3 shows a schematic view of the antenna device 10a. The electrical conductors 12a, 14a of the antenna device 10a are embedded in the carrier element 18a made of the electrically insulating material and are spaced apart perpendicular to their main extension direction 20a by a minimum distance 22a of at least 2 mm. In the present exemplary embodiment, the electrical conductors 12a, 14a are geometrically aligned parallel to one another at the predefined minimum distance 22a.

[0051] Figure 4 shows two schematic diagrams of the antenna 16a with the electrical conductors 12a, 14a. A left-hand diagram shows a simplified electrical equivalent circuit of the antenna 16a with the conductors 12a, 14a. A right-hand diagram of Figure 4 shows the structure of the antenna 16a with the electrical conductors 12a, 14a in a simplified schematic representation. The antenna 16a has an electrical resistor 54a and an inductor 56a, as well as a capacitor 52a arranged electrically parallel thereto.

[0052] The antenna 16a has a natural resonance frequency, which is calculated using the following formula (1): where f0 stands for the natural resonance frequency, TT for the piezoelectric number, L for the inductance 56a and C for the capacitance 52a.

[0053] For wireless communication via the communication unit 42a of the induction energy transmission system 26a, the antenna 16a is presently operated at a communication frequency of 13.56 MHz according to the NFC standard. To ensure interference-free communication, the natural resonant frequency fo of the antenna 16a should be significantly higher than the communication frequency and at least 25.0 MHz. To achieve values ​​of 25.0 MHz or more for the natural resonant frequency fo, the total inductance of the antenna device 10a with the antenna 16a may not exceed 3 pF, and the total capacitance of the antenna device 10a with the antenna 16a may not exceed 13 pF, with the capacitance 52a of the antenna 16a already having values ​​of 7 to 8 pF. Due to the electrical conductors 12a, 14a, the antenna device 10a additionally has a stray capacitance during operation, which together with the capacitance 52a results in the total capacitance.Due to the electrical conductors 12a, 14a, the antenna device 10a also exhibits a stray inductance during operation, which, together with the inductance 56a, results in the total inductance. The arrangement of the electrical conductors 12a, 14a has a decisive influence on the values ​​of the stray capacitance and stray inductance.

[0054] Figure 5 shows two schematic diagrams illustrating stray inductances and stray capacitances between two electrical conductors (not shown) in a non-inventive embodiment of an antenna device (not shown), wherein these electrical conductors are twisted together so that - in contrast to the antenna device 10a - the minimum distance 22a (cf. Figure 3) is not maintained.

[0055] On an abscissa 58a of an upper diagram in Figure 5, a length of the electrical conductors is plotted in cm. On an ordinate 60a of the upper diagram, a leakage inductance in pH is plotted. A best-fit line 62a is averaged through the measurement points shown in the upper diagram and shows the average increase in the leakage inductance with increasing length of the electrical conductors of the antenna device not according to the invention. From the best-fit line 62a, a specific leakage inductance of 4.6 nH / cm can be determined. It can therefore be seen that twisted electrical conductors generate a low leakage inductance, which could be compensated for by a suitable choice of the inductance of the antenna 16a so as not to exceed the desired total inductance of a maximum of 3 pH.

[0056] On an abscissa 64a of a lower diagram in Figure 5, a length of the electrical conductors is plotted in cm. On an ordinate 66a of the lower diagram, a stray capacitance in pF is plotted. A best-fit line 68a is averaged through the measurement points shown in the lower diagram and shows the average increase in stray capacitance with increasing length of the electrical conductors of the antenna device not according to the invention. From the best-fit line 68a, a specific stray capacitance of 0.75 pF / cm can be determined. It can therefore be seen that twisted electrical conductors generate a high stray capacitance, whereby even with a total length of the electrical conductors of 20 cm, the desired total capacitance of a maximum of 13 pF is exceeded by the stray capacitance alone.

[0057] Figure 6 shows a schematic diagram illustrating stray inductances between the electrical conductors 12a, 14a of the antenna device 10a.

[0058] In a current-carrying state, there is an inductive coupling between the electrical conductors 12a, 14a, which causes a specific leakage inductance of at most 13.7 nH / cm relative to a length of the electrical conductors 12a, 14a.

[0059] The length of the electrical conductors 12a, 14a is plotted in cm on an abscissa 70a of the diagram in Figure 6. A leakage inductance in pH is plotted on an ordinate 72a of the upper diagram. A best-fit line 74a is averaged through the measurement points shown in the diagram and shows the average increase in the leakage inductance with increasing length of the electrical conductors 12a, 14a. The specific leakage inductance of a maximum of 13.7 nH / cm can be determined from the best-fit line 74a. It can be seen that the electrical conductors 12a, 14 cause a higher leakage inductance compared to the non-inventive case shown in the upper diagram in Figure 5, but this can be easily compensated for by a suitable choice of the inductance 56a of the antenna 16a so as not to exceed the desired total inductance of a maximum of 3 pH.In a current-carrying state, a capacitive coupling exists between the electrical conductors 12a, 14a, which results in a specific stray capacitance of at most 0.08 pF / cm relative to a length of the electrical conductors 12a, 14a. Due to their arrangement relative to one another at the predefined minimum distance of 22 cm of at least 2 mm perpendicular to their main direction of extension 20a (see Figure 3), the specific stray capacitance between the conductors 12a, 14a is so low that it could not be directly determined in the applicant's measurement tests. The maximum value of the specific stray capacitance of 0.08 pF / cm between the electrical conductors 12a, 14a in the current-carrying state was therefore determined indirectly by measuring the natural resonant frequency fo and by inserting the measured values ​​for the stray inductance shown in the diagram in Figure 6 into formula (1) and rearranging for the capacitance C.

[0060] Figure 7 shows a schematic process flow diagram illustrating a process for producing the antenna device 10a. In the process, the electrical conductors 12a, 14a are embedded in the carrier element 18a and arranged perpendicular to their main extension direction 20a at the predefined minimum distance 22a of at least 2 mm from one another. The process comprises at least two process steps 76a, 78a. In a first process step 76a of the process, the electrical conductors 12a, 14a are embedded in the carrier element 18a and arranged perpendicular to their main extension direction 20a at the predefined minimum distance 22a of at least 2 mm from one another. In a second process step 78a of the process, a cover element (not shown) is applied to ensure that the minimum distance 22a is maintained.

[0061] Figure 8 shows a further embodiment of the invention. The following descriptions are essentially limited to the differences between the embodiments, whereby reference can be made to the description of the embodiment in Figures 1 to 7 with regard to identical components, features and functions. To distinguish the embodiments, the letter a in the reference numerals of the embodiment in Figures 1 to 7 has been replaced by the letter b in the reference numerals of the embodiment in Figure 8. With regard to components with the same designation, in particular with regard to components with the same reference numerals, reference can also be made to the drawings and / or the description of the embodiment in Figures 1 to 7.

[0062] Figure 8 shows a schematic representation of an antenna device 10b. The antenna device 10b has at least two, in this case exactly two, electrical conductors 12b, 14b. The electrical conductors 12b, 14b are provided for connection to an antenna (not shown). The antenna device 10b has a carrier element 18b, which is made of an electrically insulating material, in this case mica. The electrical conductors 12b, 14b are embedded in the carrier element 18b and have a predefined minimum distance 22b of at least 2 mm from one another perpendicular to their main extension direction 20b.

[0063] In contrast to the previous exemplary embodiment, the electrical conductors 12b, 14b are spirally shaped and are spaced at least the predefined minimum distance 22b from one another throughout. Due to the spiral shape, the specific stray inductance of an inductive coupling that exists between the conductors 12b, 14b in a current-carrying state can be reduced compared to the design of the first exemplary embodiment. At the same time, the specific stray capacitance of a capacitive coupling that exists between the conductors 12b, 14b in the current-carrying state can be kept to a value of at most 0.08 pF / cm relative to a length of the electrical conductors 12b, 14b by maintaining the minimum distance 22b.

[0064] Reference symbol

[0065] 10 Antenna device

[0066] 12 electrical conductors

[0067] 14 electrical conductor

[0068] 16 Antenna

[0069] 18 support element

[0070] 20 Main direction of extension

[0071] 22 Minimum distance

[0072] 26 Induction energy transfer system

[0073] 28 Induction device

[0074] 30 mounting plate

[0075] 32 Inductor

[0076] 34 Insulation element

[0077] 36 Installation unit

[0078] 38 additional installation units

[0079] 40 Recording inductor

[0080] 42 Communication unit

[0081] 44 Control unit

[0082] 46 Communication element

[0083] 48 additional communication element

[0084] 50 additional communication elements

[0085] 52 capacity

[0086] 54 electrical resistance

[0087] 56 Inductance

[0088] 58 Abscissa

[0089] 60 ordinates

[0090] 62 best-fit lines

[0091] 64 Abscissa

[0092] 66 Ordinate Best fit line Abscissa Ordinate Best fit line first step second step

Claims

Claims 1. Antenna device (10a; 10b), in particular NFC antenna device, with at least two electrical conductors (12a, 14a; 12b, 14b) for connection to an antenna (16a), characterized in that the electrical conductors (12a, 14a; 12b, 14b) are embedded in a carrier element (18a) made of an electrically insulating material and have a predefined minimum distance (22a; 22b) of at least 2 mm from one another perpendicular to their main direction of extension (20a; 20b).

2. Antenna device (10a; 10b) according to claim 1, characterized in that the carrier element (18a) is made of mica.

3. Antenna device (10a; 10b) according to claim 1 or 2, characterized in that the carrier element (18a) is flat.

4. Antenna device (10a; 10b) according to one of the preceding claims, characterized by the antenna (16a) which is formed integrally with the electrical conductors (12a, 14a; 12b; 14b).

5. Antenna device (10a; 10b) according to one of the preceding claims, characterized in that a capacitive coupling exists between the electrical conductors (12a, 14a; 12b; 14b) in a current-carrying state, which causes a specific stray capacitance of at most 0.08 pF / cm based on a length of the electrical conductors (12a, 14a; 12b, 14b).

6. Antenna device (10a; 10b) according to one of the preceding claims, characterized in that an inductive coupling exists between the electrical conductors (12a, 14a; 12b, 14b) in a current-carrying state, which inductive coupling causes a specific leakage inductance of at most 13.7 nH / cm based on a length of the electrical conductors (12a, 14a; 12b, 14b).

7. Antenna device (10a) according to one of the preceding claims, characterized in that the electrical conductors (12a, 14a) are aligned geometrically parallel to one another at the predefined minimum distance (22a).

8. Antenna device (10b) according to one of claims 1 to 6, characterized in that the electrical conductors (12b, 14b) are spirally shaped and have at least the predefined minimum distance (22b) from one another everywhere.

9. Induction energy transmission system (26a) with at least one antenna device (10a; 10b) according to one of the preceding claims.

10. Induction energy transmission system (26a) according to claim 8, characterized by an induction device (28a) with a mounting plate (30a), with at least one inductor (32a) arranged below the mounting plate (30a) and with at least one insulation element (34a) arranged between the inductor (32a) and the mounting plate (30a), wherein the insulation element (34a) functions as the carrier element (18a) for the electrical conductors (12a, 14a; 12b, 14b) of the antenna device (10a; 10b).

11. A method for producing an antenna device (10a; 10b), in particular according to one of claims 1 to 8, with at least two electrical conductors (12a, 14a; 12b, 14b) for connection to an antenna (16a), characterized in that the electrical conductors (12a, 14a; 12b, 14b) are embedded in a carrier element (18a) made of an electrically insulating material and are arranged perpendicular to their main extension direction (20a; 20b) at a predefined minimum distance (22a; 22b) of at least 2 mm from one another.

Images