EP3920326A1 - Antennenanordnung für elektronischen fahrzeugschlüssel - Google Patents

Antennenanordnung für elektronischen fahrzeugschlüssel Download PDF

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Publication number
EP3920326A1
EP3920326A1 EP20465533.6A EP20465533A EP3920326A1 EP 3920326 A1 EP3920326 A1 EP 3920326A1 EP 20465533 A EP20465533 A EP 20465533A EP 3920326 A1 EP3920326 A1 EP 3920326A1
Authority
EP
European Patent Office
Prior art keywords
antenna
section
antenna section
inductive element
circuitry
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20465533.6A
Other languages
English (en)
French (fr)
Inventor
Andreea c/o Continental Automotive GmbH Hadarig
Razvan c/o Continental Automotive GmbH Bejinaru
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aumovio Germany GmbH
Original Assignee
Continental Automotive Technologies GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Automotive Technologies GmbH filed Critical Continental Automotive Technologies GmbH
Priority to EP20465533.6A priority Critical patent/EP3920326A1/de
Publication of EP3920326A1 publication Critical patent/EP3920326A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H01Q1/3208—Adaptation for use in or on road or rail vehicles characterised by the application wherein the antenna is used
    • H01Q1/3233—Adaptation for use in or on road or rail vehicles characterised by the application wherein the antenna is used particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
    • H01Q1/3241—Adaptation for use in or on road or rail vehicles characterised by the application wherein the antenna is used particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems particular used in keyless entry systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/24—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
    • H01Q3/247—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching by switching different parts of a primary active element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30—Arrangements for providing operation on different wavebands
    • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
    • H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
    • H01Q5/321—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors within a radiating element or between connected radiating elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole

Definitions

  • the current invention relates to an antenna arrangement, in particular an antenna arrangement for an electronic vehicle key.
  • a vehicle key Most vehicles today may be unlocked and remotely started using an electronic vehicle key.
  • Some "start and stop” access systems are well known in which the user needs to press an unlocking button from the electronic remote key to unlock or lock the vehicle, start the engine of the vehicle, or open a trunk of the vehicle, for example.
  • Such an electronic vehicle key usually has to be inserted into an immobilizer station located inside the vehicle which recognizes the vehicle key and allows the user to start the vehicle.
  • Such systems replace the originally known ignition switch systems.
  • Other “start and stop” access systems do not require the user to press a button or to insert the key in an immobilizer in order to unlock or lock the vehicle or to start the engine.
  • Such a “start and stop” access system is called a passive start and entry system, or remote keyless entry system (RKE).
  • RKE remote keyless entry system
  • an electronic vehicle key communicates with the vehicle using wireless technology.
  • an electronic vehicle key usually comprises two or even more different antennas.
  • an electronic vehicle key may comprise at least one low frequency (LF) antenna, one ultra-high frequency (UHF) antenna, and an antenna for Bluetooth communication.
  • Bluetooth or Bluetooth Low Energy (BLE) communication may be used, for example for transmitting all kind of information (e.g., tire pressure, fuel status, etc.) from the vehicle to the vehicle key or to a portable electronic device (e.g., smartphone).
  • At least one of the antennas may be implemented as a loop antenna.
  • Many different antennas are generally all integrated in the vehicle key, the vehicle key having comparably small dimensions. When the number of antennas increases, however, the space requirements in the vehicle key increase.
  • An antenna arrangement includes a first antenna section, a second antenna section, an antenna circuitry, and an inductive element.
  • the first antenna section is coupled between the antenna circuitry and a first terminal of the inductive element
  • the second antenna section is coupled between a second terminal of the inductive element and the antenna circuitry, and in series to the first antenna section and the inductive element.
  • the antenna arrangement can be implemented in a very space saving and cost-effective way.
  • a single antenna arrangement may be used for two different frequency ranges.
  • the second antenna section may be decoupled from the first antenna section by the inductive element such that only the first antenna is used to transmit and receive signals.
  • the first antenna section and the second antenna section together may form an antenna that is used to transmit and receive signals.
  • the inductive element may comprise an inductance of 10nH, in order to effectively decouple the second antenna section from the first antenna section at a first frequency, and to allow the first and second antenna section to form a single antenna at a frequency range that is different from the first frequency.
  • the first antenna section when decoupled from the second antenna section, may form a monopole antenna.
  • the second antenna section together with the first antenna section may form a loop antenna.
  • the antenna arrangement may further include a switching element coupled between the antenna circuitry and the series connection including the first antenna section, the second antenna section and the inductive element.
  • the antenna circuitry may include a first branch comprising a Bluetooth circuitry and a Bluetooth matching circuit.
  • the antenna circuitry may further include a second branch comprising an ultra-high frequency circuitry and an ultra-high frequency matching circuit.
  • the switching element may be configured to couple the series connection including the first antenna section, the second antenna section and the inductive element either to the first branch or to the second branch.
  • the antenna may be operated at a different frequency.
  • a single antenna arrangement therefore, may be used to perform two different wireless services or applications.
  • An electrical length of the first antenna section may equal a quarter of the resulting wavelength when the antenna arrangement is operated at a frequency of 2.4GHz.
  • the first antenna section, the second antenna section, the inductive element and the antenna circuitry may be arranged on a printed circuit board.
  • An electronic vehicle key may include an antenna arrangement as described above.
  • Figure 1 illustrates an antenna arrangement that may be arranged in an electronic vehicle key.
  • Signals may be sent between a vehicle and the electronic vehicle key (vehicle not illustrated in Figure 1 ).
  • the electronic vehicle key may send inquiry signals to the vehicle to indicate the desire of a user to unlock/lock the vehicle.
  • authentication signals may be sent between the electronic vehicle key and the vehicle, for example, in order to prevent unauthorized users (unauthorized keys) from unlocking or starting the vehicle.
  • Many other signals may be sent between the electronic vehicle key and the vehicle for many different applications.
  • An electronic vehicle key may comprise different antennas.
  • a first antenna may be a low frequency (LF) antenna, for example. Low frequency signals may be sent at frequencies in the range between 30 to 300kHz, for example.
  • a second antenna may be a radio frequency (RF) or ultra-high frequency (UHF) antenna, for example. Radio frequency signals may be sent at frequencies in the range between 20kHz to 300GHz.
  • An even further antenna may be an antenna that is configured to transmit and receive signals according to the Bluetooth standard at a frequency of 2.4GHz.
  • the antenna arrangement illustrated in Figure 1 comprises an antenna circuitry 21, a first antenna section 31, a second antenna section 32, and an inductive element 40.
  • the inductive element 40 is coupled between and in series to the first antenna section 31 and the second antenna section 32. That is, the first antenna section 31 is coupled to the antenna circuitry 21 with a first end, and to a first terminal of the inductive element 40 with a second end.
  • the second antenna section 32 is coupled to a second terminal of the inductive element 40 with a first end, and to the antenna circuitry 21 with a second end.
  • the inductive element 40 is configured to decouple the second antenna section 32 from the first antenna section 31 at specific frequencies. For example, when the antenna arrangement is operated at a frequency of 2.4GHz, the second antenna section 32 may be decoupled from the first antenna section 31. In other words, at a frequency of 2.4GHz, only the first antenna section 31 may be used to transmit and receive signals, while the second antenna section 32 becomes "invisible" and is not used for transmitting and receiving.
  • the inductive element 40 for example, may comprise a capacitance of 10nH.
  • the first antenna section 31 and the second antenna section 32 together form a loop antenna for transmitting and receiving signals in the ultra-high frequency band.
  • the inductive element 40 in this case (at frequencies of between 300MHz and 500MHz) has a low impedance and, therefore, does not have an influence on the behavior of the loop antenna formed by the first antenna section 31 and the second antenna section 32. That is, the ultra-high frequency signal can flow unhindered through the loop formed by the first antenna section 31 and the second antenna section 32.
  • the antenna arrangement may be operated at a frequency of 315MHz or 434MHz.
  • the loop antenna formed by the first antenna section 31 and the second antenna section 32 may be a small loop antenna, for example.
  • the first antenna section 31, when operated separately (second antenna section 32 is decoupled) may form a monopole antenna.
  • the first antenna section 31, the second antenna section 32, the inductive element 40 and the antenna circuitry 21 may all be arranged on a printed circuit board 10.
  • An electrical length of the first antenna section 31 may equal a quarter of the resulting wavelength when the first antenna section 31 is operated at a frequency of 2.4GHz. That is, the inductive element 40 may be arranged at a position along the loop antenna formed by the first antenna section 31 and the second antenna section 32 which is arranged at a first distance with respect to a feeding point, wherein the first distance equals a quarter of the resulting wavelength when the antenna arrangement is operated at a frequency of 2.4GHz.
  • the first antenna section 31 and the second antenna section 32 are both integrated into a single topology while keeping the electrical behavior of each antenna (BLE antenna, UHF antenna) essentially unaffected.
  • the first antenna section 31 and the second antenna section 32 may each be implemented as a copper trace on the printed circuit board 10, for example.
  • FIG. 2A an ultra-high frequency antenna input impedance is schematically illustrated for an ultra-high frequency antenna that does not comprise an inductive element 40 (without decoupling circuit).
  • Figure 2A shows both a real part of the impedance (curve having the lower peak, illustrated in a solid line), and an imaginary part of the impedance (curve having the higher peak, illustrated in a dashed line).
  • Figure 2B schematically illustrates an ultra-high frequency antenna input impedance for an ultra-high frequency antenna comprising an inductive element 40 as exemplarily illustrated in Figure 1 (with decoupling circuit).
  • Figure 2B also shows both a real part of the impedance (curve having the lower peak, illustrated in a solid line), and an imaginary part of the impedance (curve having the higher peak, illustrated in a dashed line).
  • the differences in the desired frequency range are marginal with or without the inductive element 40.
  • the inductive element 40 does not essentially affect the antenna impedance.
  • FIG. 3A an input impedance of a BLE antenna is schematically illustrated for a BLE antenna without an inductive element 40 (without decoupling circuit).
  • Figure 2A also shows both a real part of the impedance (curve having the higher peak, illustrated in a solid line), and an imaginary part of the impedance (curve having the lower peak, illustrated in a dashed line).
  • Figure 3B schematically illustrates in a diagram a BLE antenna input impedance for a BLE antenna comprising an inductive element 40 as exemplarily illustrated in Figure 1 (with decoupling circuit).
  • Figure 3B also shows both a real part of the antenna impedance (curve arranged in upper half of diagram, illustrated in a solid line), and an imaginary part of the antenna impedance (curve starting in lower left part of diagram and ending in upper right part of diagram, illustrated in a dashed line).
  • the input impedance of the first antenna section 31 may be as close as possible to 50Ohm. This results in an input reflection coefficient of below -6dB.
  • Figure 6 illustrates a comparison between the frequency response of a BLE antenna with (curve with deep valley at BLE frequency, solid line) and without an inductive element 40 (upper curve, dashed line).
  • the input reflection coefficient can be improved to below -10dB at the desired frequencies by the use of a simple matching circuit (e.g., two components, namely one series capacitance/inductance and one shunt capacitance/inductance).
  • the antenna arrangement may further comprise a switching element 50 coupled between the antenna circuitry 21 and the series connection including the first antenna section 31, the second antenna section 32 and the inductive element 40.
  • this series connection is schematically represented by a single antenna 33.
  • the antenna circuitry 21 may comprise a first branch comprising a Bluetooth circuitry (or Bluetooth Low Energy circuitry) 71 and a Bluetooth (or Bluetooth Low Energy) matching circuit 61.
  • the antenna circuitry 21 may further comprise a second branch comprising an ultra-high frequency circuitry 72 and an ultra-high frequency matching circuit 62.
  • the switching element 50 may be configured to couple the series connection including the first antenna section 31, the second antenna section 32 and the inductive element 40 (antenna 33) either to the first branch or to the second branch.
  • the antenna 33 when connected to the first branch, the antenna 33 may be operated at a frequency of 2.4GHz to perform Bluetooth or Bluetooth Low Energy communication.
  • the second antenna section 32 in this case may be "invisible", as has been described above.
  • the antenna 33 When connected to the second branch, the antenna 33 may be operated at frequencies falling into the ultra-high frequency range (e.g., 315MHz, or 434MHz). That is, when the antenna 33 is coupled to the second branch, the first antenna section 31 and the second antenna section 32 may together form a loop antenna.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Details Of Aerials (AREA)
EP20465533.6A 2020-06-05 2020-06-05 Antennenanordnung für elektronischen fahrzeugschlüssel Withdrawn EP3920326A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP20465533.6A EP3920326A1 (de) 2020-06-05 2020-06-05 Antennenanordnung für elektronischen fahrzeugschlüssel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP20465533.6A EP3920326A1 (de) 2020-06-05 2020-06-05 Antennenanordnung für elektronischen fahrzeugschlüssel

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EP3920326A1 true EP3920326A1 (de) 2021-12-08

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EP20465533.6A Withdrawn EP3920326A1 (de) 2020-06-05 2020-06-05 Antennenanordnung für elektronischen fahrzeugschlüssel

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2361584A (en) * 2000-04-19 2001-10-24 Motorola Israel Ltd Multi-band antenna and switch system
US9019163B2 (en) * 2011-10-27 2015-04-28 Panasonic Intellectual Property Corporation Of America Small antenna apparatus operable in multiple bands including low-band frequency and high-band frequency with ultra wide bandwidth

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2361584A (en) * 2000-04-19 2001-10-24 Motorola Israel Ltd Multi-band antenna and switch system
US9019163B2 (en) * 2011-10-27 2015-04-28 Panasonic Intellectual Property Corporation Of America Small antenna apparatus operable in multiple bands including low-band frequency and high-band frequency with ultra wide bandwidth

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
G.-A. CHAKAM ET AL: "Comparison of key-FOB antennas for vehicle access system", EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION : EUCAP 2007 ; 11 - 16 NOVEMBER 2007, EICC, EDINBURGH, UK, 11 November 2007 (2007-11-11), pages 610 - 610, XP055745862, ISBN: 978-0-86341-842-6, DOI: 10.1049/ic.2007.1137 *
SAOU-WEN SU: "CAPACITOR-INDUCTOR-LOADED, SMALL-SIZED LOOP ANTENNA FOR WLAN NOTEBOOK COMPUTERS", PROGRESS IN ELECTROMAGNETICS RESEARCH M, vol. 71, 10 August 2018 (2018-08-10), pages 179 - 188, XP055745188, DOI: 10.2528/PIERM18061904 *

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