Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
  • H01Q1/521—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas
  • H01Q1/525—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas between emitting and receiving antennas
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
  • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
  • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
  • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
  • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
  • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
  • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
  • G06K7/10356—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• • 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
  • H01Q7/06—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 with core of ferromagnetic material
  • H01Q7/08—Ferrite rod or like elongated core
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
  • H04B5/40—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by components specially adapted for near-field transmission
  • H04B5/43—Antennas
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
  • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes

Definitions

• the invention concerns an antenna system which has one transmitting solenoid antenna and one receiving solenoid antenna, whereby both antennas have mutual spatial arrangement which produces their mutual electromagnetic isolation while they simultaneously transmit and receive the signal.
• the antenna system takes up little available space on the, for example, PCB (printed-circuit board) of the mobile phone, SiP (System in Package) module, SD memory card, USB stick and so on.
• PCD passive mode initializer/receiver
• PICC transponder/receiver
• load modulation modulation of the carrier field
• the antenna system is formed by two solenoid antennas and a flat antenna, whereby antennas have a geometrical arrangement which allows for placement of other electronic elements in the space between the two solenoid antennas. This improves the availability of the space, but it still leads to relatively large outer dimensions of PCB pursuant to the size of the flat antenna.
• Majority of the solutions with the independent transmitting and receiving antenna use a flat antenna with relatively large dimensions which correspond to a standard, which provides the possibilities of radiation (emission) of a sufficient power for excitation of the transponder/receiver (PICC). If the antenna system diminishes further, the diminishment of the flat antenna leads to problems with a sufficient emitting power, which is manifested by the decrease in the distance in which the NFC channel can stably communicate.
• a solution is desired and not known, which will achieve, compared to the prior art, sufficiently strong isolation of the transmitting and receiving antenna so that the influence / interference of transmitting and receiving circuits of the controller does not take place, whereby it is possible to achieve additional transmitting and receiving power of the antenna system on the small available surface, and this during simultaneous transmission and reception.
• a requested feature of the new solution is also its capability to operate both in CE and RW mode on both ends of the communication channel.
• both solenoid antennas designed especially for an NFC reception and transmission, where both antennas have a magnetic core and they are placed in the same base plane, according to this invention which essence lies in the fact that the first solenoid antenna is shorter than the second solenoid antenna, both solenoid antennas have parallel longitudinal axes and the longitudinal center of the first solenoid antenna’s core is at the level of the first thread of the second solenoid antenna.
• the parallel nature of the longitudinal antennas means that the solenoid antennas’ cores are parallel, whereby their mutual position can deviate from being exactly parallel within an allowed production margin of error, usually up to 5°.
• the term“solenoid antenna” denotes a coil with multiple windings of the conductor on the core, for example on the core of the rectangular cross- section, where the length (longitudinal dimension) of the core is more than its transverse dimension; usually the length of the coil is more than five times the diagonal of the cross-section (for example, when the cross-section of the core is rectangular).
• the width of the core is a transverse dimension of the core by which the core is projected into the groundplan of the antenna’s carrier, that is, onto the plane of the base. In case of the oblong cross-section of the core the core’s width is a dimension in the direction parallel with the plane of the base; in case of the circular cross-section of the core the width of the core is its diameter.
• the core can be ferrite or from the material with similar magnetic features.
• the length of the solenoid antenna denotes an overall length of the core or the core’s length covered with the conductor’s threads.
• the basic feature of the invention is the mutual parallel placement of two differently long solenoid antennas, whereby the first, shorter solenoid antenna is by its longitudinal center placed at the end of the second, longer solenoid antenna.
• the spatial and dimensional configuration according to this invention ensures a selective non-sensitivity of the receiving antenna, which is capable of receiving the outside signal from the alien source (PCD) during active transmission of the close antenna within a common antenna system. It is not necessary to complicatedly process and filter the received signal.
• both solenoid antennas will be connected to the respective circuits of a single NFC chip (controller) through its own adapting (binding) elements.
• the first, shorter solenoid antenna serves as a receiving antenna and it is connected by means of its adapting circuit to the receiving entry into an NFC chip (RX outputs, where R denotes receiving).
• the second, shorter solenoid antenna serves as a transmitting antenna which is connected by means of its adapting circuit to the transmitting output of an NFC chip (TX outputs, where T denotes transmitting).
• the main advantage of the proposed invention is more effective use of the potential of the output circuit of a given NFC chip and achievement of the maximum possible radiating power without the decrease of the receiving capabilities of the NFC chip by low entry signal or by interference from the transmitting part.
• the first solenoid antenna and the second solenoid antenna are mutually coupled by air coupling (or similar coupling through a non- conductive environment); its parameters are affected by a distance of the longitudinal axes of the solenoid antennas.
• the distance of the longitudinal axes of both solenoid antennas will be less than 8 mm, preferably less than 4 mm, for example 2,6 mm.
• the antenna is supposed to operate in CE (Card Emulation) mode as well as in RW (Read/Write) mode, that is, if it is supposed to be capable of communicating with a reader and in another communication case the identical antenna system should form a reader for a card, there are then opposite demands placed upon the design of the antenna system.
• the communication counterpart in the antenna system according to this invention is a reader (PCD) or a transponder (PICC), depending on whether the antenna system according to this invention operates in CE or RW mode.
• PCD reader
• PICC transponder
• the second demand is opposite: it demands weak link between first and second solenoid antenna so that the transmissions do not cancel themselves out and therefore the synchronization with the reader in case of CE mode is not lost, or that the inherent entry circuits in RW mode are not excited or overexcited, respectively.
• the longitudinal center of the first solenoid antenna’s core is at the level of the thread of the second solenoid antenna. This requires a position of the center of the first solenoid antenna at the end of the second solenoid antenna’s core.
• the level of the first thread denotes mainly a longitudinal center of the first thread in a projection onto the longitudinal axis of the second solenoid antenna.
• the level of the center of the first solenoid antenna can deviate from the level of the center of the first thread; it can be by its beginning or its end, where the second thread of the second solenoid antenna begins, as depicted in figure 11.
• the optimal level of the first solenoid antenna can move within a tolerance of 4 mm in direction of longitudinal axes and in tolerance of 2 mm concerning the dimension of the distances of the longitudinal axes.
• Both solenoid antennas are preferably placed in a common substrate, that is, on the same surface, for example on a single surface of the PCB or on the opposite surfaces of a single PCB.
• a realization is also possible, though, where the antennas are on different planes or, eventually, on independent carriers; it is important, though, that the mutually parallel arrangement with a shift of the center of one solenoid antenna against towards first thread of the other solenoid antenna, is achieved.
• Such placement achieves preferable use of the available space; a sufficient isolation is produced even when the antennas are basically completely close to each other. Thanks to this, a good use is made of available building space, and the transmitting power (performance) is increased, respectively.
• the antenna system includes first solenoid antenna with a flat winding of the loops, whereby its length is up to 10 mm.
• First solenoid antenna can have cylindrical or rectangular cross-section of the core.
• the cross-section of the core in a preferable miniature realization can have dimension, for example, 0,6 mm x 0,8 mm (height x width).
• a flat cross-section of the conductor can be substituted for the multiply repeated placement of the circular conductor within a single thread.
• the number of threads of first solenoid antenna is usually larger or smaller than the number of threads of second solenoid antenna.
• the second solenoid antenna can have between 21 to 26 threads.
• the second solenoid antenna can have smaller number of threads than first solenoid antenna, usually not less than 75% of the number of threads of the first solenoid antenna.
• the number of threads of first and second solenoid antenna is not directly proportional to the number of their lengths.
• both solenoid antennas can have identical number of threads.
• the number of threads and their ratio will depend mainly on the permeability of the core of the first and second solenoid antenna, whereby we strive to achieve the inductance of the second solenoid antenna with the range 1 ,0 to 1 ,5 pH.
• the second solenoid antenna has 20% to 30% more threads compared to the number of threads of the first solenoid antenna.
• the ratio of length of the first solenoid antenna to the length of the second solenoid antenna will range from 1 :1 ,1 to 1 :4, preferably from 1 :2 to 1 :3.
• the ratio of the number of threads will range from 1 :0,7 to 1 :1 ,3.
• the second solenoid antenna has, in preferable arrangement, flat winding of the threads, whereby there are gaps between the windings on the core.
• the length of the second solenoid antenna ranges up to 30 mm.
• the second solenoid antenna can have threads formed by a multistep winding of the wire, which produces a flat conductor of a single wire.
• a conductor with a circular cross-section can achieve similar effect as is achieved in case of a wide flat conductor which is, however, problematically wound onto a small core. It is thus preferable if multiple conductors are wound by each other within a single winding; preferably the number of wound conductors within a single winding is 6 to 10, especially preferably they are 9. This achieves the desired ratio of the width of a single winding to the thickness (height) of the winding.
• a thin substrate is a component of the first and/or second solenoid antenna, whereby this substrate is wound to the bottom surface of the core during the winding of the conductor to the core.
• the small conductive surfaces are produced on the substrate on its ends, whereby the ends of the conductors are connected to them.
• the small conductive surfaces are subsequently used for connection to the PCB, preferably by means of SMD mounting (surface-mounting).
• First and/or second solenoid antenna can in another arrangement have windings formed by wire bonding.
• the wire can be flat or one can reuse multiple wires with the standard circular cross-section within a single thread.
• the wire during bonding is surrounded by the core placed on the substrate with the small conductive surfaces. The bonding also binds the core to the substrate.
• the received signal from the initializer is only minimally interfered by the transmission of the transponder thanks to the isolation, and no additional external synchronization circuits are necessary.
• the signal received by the transponder in such a way is during the active modulation repeatedly transmitted back as a modulation carrier wave for the data modulation, which ensures that both signals are precise as far as their frequency is concerned.
• the identical antenna system according to this invention can effectively function on both sides of the NFC communication channel, both in CE and RW mode.
• the second, larger solenoid antenna is capable of radiating sufficient power for excitation of the passive card approaching the antenna system.
• the advantage of the invention is also the simple arrangement of the antenna system and simple connection of the respective circuits, whereby thanks to the physical binds between the transmitting and receiving antenna a high efficacy on small build-up surface is achieved.
• Figure 1 depicts the placement of the first solenoid antenna and the second solenoid antenna on the small PCB communication module with the adaptation circuits designed for the connection to the NFC controller.
• the axis marked as a1 is transverse axis of the first solenoid antenna and its marked position is at the level of the first thread of the second solenoid antenna.
• the depicted ratio of sizes of first and second solenoid antenna is for information purposes and the particular ratio was chosen for the purposes of clarity.
• Figure 2 depicts the position of both antennas from the first figure, where the dimension “a” forms a distance of the transverse axes of the solenoid antennas.
• Figure 3 continues to mark possible positions of the first solenoid antenna, where Aa is a range of the positioning of the transverse axes of the solenoid antennas and Ab is a range of the positioning of the longitudinal axes of the solenoid antennas.
• Figure 4 depicts the connection of both solenoid antennas to the NFC controller.
• Figure 5 depicts the coupling between the antennas during the creation of the communication channel with the reader and card in the position of the counterpart.
• Coefficient k1 expresses the coupling between the antenna of the communication counterpart and the first solenoid antenna (RX).
• Coefficient k2 expresses the coupling between the antenna of the communication counterpart and second solenoid antenna (TX).
• Coefficient k3 expresses the coupling between the first solenoid antenna (RX) and second solenoid antenna (TX).
• Figure 6 depicts the construction of the second solenoid antenna.
• N is the number of threads; L is the length; s is the size of the gap between threads; n denotes a single thread.
• Figure 7 is a graph of dependence of the number of threads of the second solenoid antenna on its length.
• Figure 8 is a graph of the dependence of the size of the gap between the threads of the second solenoid antenna on its length.
• Figure 9 is a view of the edge of the core of the first solenoid antenna with six conductors of the circular cross-section within a single thread, where one can see that the thread on the edge has an increased pitch, so that the group of the conductors of a single thread is separated for the purposes of connection to the small conductive surface.
• the letter“n” denotes a single thread.
• Figure 10 is an axonometric view of the communication module with the adapting circuits and both solenoid antennas.
• Figure 11 depicts the detail of the position of the center of the first solenoid antenna against the first thread of the second solenoid antenna.
• the hatched strip denotes various points of the position at the level of the first thread.
• the dashed line depicts the edge of the winding on the opposite side of the core. For the purposes of clarity the slope (angle) of the winding on the sides of the core is not depicted. Examples of realization
• the antenna system has first solenoid antenna 1 and second solenoid antenna 2. Both have a ferrite core.
• the cross-section of the core of the first solenoid antenna 1 has dimensions 0,6 mm x 0,8 mm.
• the conductors of the threads are wound in the even slope (angle) except for the ends of the first and last thread, whereby the ends have an increased slope in order to achieve the distance of the group of conductors for their connection to the small conductive surfaces on the substrate.
• the second solenoid antenna’s 2 core has cross-section 0,6 mm x 1 ,6 mm. Both antennas are placed on a single surface of a common carrier. They are placed in parallel and the center of the first solenoid antenna 1 is at the level of the first thread 3 of the second solenoid antenna 2.
• the distance of the longitudinal axes of the solenoid antennas 1, 2 in this case is 2,6 mm.
• the windings are from copper wire with the circular cross-section. The multiple placement of the conductor side by side within a single thread produces an effect of the flat conductor.
• Each solenoid antenna 1_, 2 has its own adaptation circuit 5, 6 and these are connected to the common NFC controller 7.
• the antenna system suppresses the interference with the need for active suppression of active circuits. This removes the problem in case of miniature NFC antennas which require active load modulation, where the active signal from the point of view of the receiver manifests itself as interference, and as a result the quality of reception decreases.
• Antenna system is suitable for use in the mobile phone, SiP modules of various devices, SD cards, and it is suitable both for read/write mode and Card Emulation mode.
• the second solenoid antenna 2 has the length of a core 20 mm, it has 22 threads and each thread is formed by nine conductors placed side by side.
• the gap between the neighboring threads on the second solenoid antenna’s 2 core is 0,35 mm.
• the second solenoid antenna’s 2 core has a cross-section 0,6 mm x 1 ,6 mm.
• Second solenoid antenna 2 has a length of a core 23 mm; it has 23 threads.
• the thread is formed by nine conductors placed side by side.
• the gap between neighboring threads is 0,45 mm.
• the core’s cross-section is 0,6 mm x 1 ,6 mm.
• Second solenoid antenna 2 has a length of a core 25,5 mm; it has 24 threads.
• the thread is formed by nine conductors placed side by side.
• the gap between neighboring threads is 0,52 mm.
• the core’s cross-section is 0,6 mm x 1 ,6 mm.
• Second solenoid antenna 2 has a length of a core 28 mm; it has 28 threads.
• the thread is formed by nine conductors placed side by side.
• the gap between neighboring threads is 0,58 mm.
• the core’s cross-section is 0,6 mm x 1 ,6 mm.
• the first solenoid antenna 1 has identical construction as in previous examples and its length is 9 mm.
• the second solenoid antenna 2 has a core’s length chosen pursuant to the largest available space in a given PCB 4, whereby the number of threads and the size of the gaps between threads is chose pursuant to graphs in figures 7 and 8.
• First solenoid antenna 1 has a ferrite core and the threads are formed by a multiple placement of the copper wire in a single thread.
• the longitudinal cross-section of the core has dimensions 0,6 mm - 0,8 mm and length 9 mm.
• the second solenoid antenna 2 is formed by bonding.
• the conductive loops envelop the core placed on the non-conductive substrate; part of the conductive substrate is formed by the flat circuit on the board where the group of conductive strips placed side by side is produced, whereby the core is placed on these strips.
• the core can be placed directly onto the board or onto the substrate.
• the conductive strips overhang thorugh the core’s groundplan; the ends of the conductive strips overhanging on both sides of the core form a little connecting surfaces.
• Wires shaped for the enveloping of the core are connected to the connecting surfaces, whereby the wire connects the connecting surface of a single conductive strip with the connecting surface on the opposite end of the neighboring conductive strip.
• the conductive strip and the wire form conductors of the individual loops; the loops envelop the core of the antenna.
• the wire in this example has flat cross-section.
• the industrial applicability is obvious. According to this invention it is possible to industrially and repeatedly compose and use antenna system with two solenoid antennas for transmission and reception of the signal, whereby the antenna system is effective in both CE and RW mode.

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Citations (3)

• 2019
  • 2019-02-27 SK SK50007-2019A patent/SK500072019A3/sk unknown
• 2020
  • 2020-02-25 WO PCT/IB2020/051588 patent/WO2020174385A1/en active Application Filing

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