Thus, the single structure antenna of the present disclosure is of an efficient design that is capable of operating over multiple frequencies having an optimized inductance and quality factor that comprises at least two inductor coils that are electrically connected in series. The single structure antenna of the present disclosure enables the antenna to be tuned to a multitude of customizable frequencies and frequency bands to facilitate optimized wireless transfer of electrical energy and/or data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a prior art four terminal two-structure dual mode antenna.

FIG. 2 shows an embodiment of a three terminal single structure multiple mode antenna of the present disclosure comprising a switch circuit.

FIG. 2A is an electrical schematic diagram of the three terminal single structure multiple mode antenna illustrated in FIG. 2.

FIG. 3 illustrates an embodiment of a three terminal single structure multiple mode antenna of the present disclosure.

FIG. 3A is an electrical schematic diagram of the three terminal embodiment of the antenna shown in FIG. 3.

FIG. 3B is an embodiment of a first layer of a multi-layer single structure multiple mode antenna of the present disclosure.

FIG. 3C is an embodiment of a second layer of a multi-layer single structure multiple mode antenna of the present disclosure.

FIG. 3D illustrates a magnified view of a portion of an inductor coil having a plurality of shunted via connections.

FIG. 3E is an embodiment of a three terminal single structure multiple mode antenna of the present disclosure in which the respective terminals are connected to a single filar.

FIG. 3F is a magnified view showing an embodiment in which the filars of an inductor coil are electrically bypassing the terminal lines.

FIG. 4 is an electrical schematic diagram of the four terminal antenna embodiment of the present disclosure shown in FIG. 4.

FIG. 5 shows an embodiment of a single structure multiple mode antenna of the present disclosure comprising a conductive filar with a variable width.

FIGS. 6A-6E illustrate cross-sectional views of different embodiments of the antenna of the present disclosure with different ferrite material shielding configurations.

FIG. 7 is a flow diagram that illustrates an embodiment of a fabrication process of a single structure antenna of the present disclosure.

FIG. 8A illustrates an embodiment of the magnetic field strengths generated by a single turn coil antenna.

FIG. 8B illustrates an embodiment of the magnetic field strengths generated by a two turn coil antenna.

FIG. 8C illustrates an embodiment of the magnetic field strengths generated by a three turn coil antenna.

FIG. 9 shows an embodiment of a two coil antenna fabricated from a metal stamping process.

FIG. 10 is a flow chart that illustrates an embodiment of a fabrication process of a single structure antenna of the present disclosure having a unitary body structure.

FIG. 11 shows a theoretical embodiment of a single structure antenna of the present disclosure comprising n+1 number of terminals.

FIGS. 12A-12C illustrate various embodiments of electrical switch configurations that provide different electrical connections between inductor coils.

FIG. 13 is a flow chart that illustrates an embodiment of operating a single structure antenna of the present disclosure.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

The antenna and communication system thereof of the present disclosure provides for improved induction communication, such as near field communication. More specifically, the antenna of the present disclosure is of a single structure design that enables coupled magnetic resonance. Coupled magnetic resonance is an alternative technology that when appropriately designed, can provide for increased wireless power transfer and communication efficiencies and is less dependent of physical orientation and positioning requirements of prior art antennas. As a result, the antenna of the present disclosure provides for improved wireless transfer efficiency and a better user experience.

The multi-band single structure antenna of the present disclosure also enables increased transmission range. As will be discussed in more detail, the structure of the antenna of the present disclosure enables tuning of the operating frequency. This enables the operator to quickly modify the receiving antenna's operating frequency to match the frequency of the transmitted signal or, alternatively, transmit a signal at an increased frequency using a frequency multiplier to match the increased operating frequency of a receiving antenna. Furthermore, the single structure antenna of the present disclosure may also comprise a selection circuit which may be capable of conditioning or modifying the received or transmitted signal. An example of which includes modifying the operating frequency of the antenna by a frequency multiplying factor to increase range.

In addition, the antenna of the present disclosure enables increased operating frequencies. Operating at a higher frequency range provides for smaller antenna form factors. For example, consider a generic transmitting and receiving antenna combination both operating at a frequency (ω) that are spaced a distance d apart and have a coupling factor, k. The transmitting antenna has a transmitting antenna inductance (LT_x) and the receiving antenna has a receiving antenna inductance (LR_x). In this scenario, the induced voltage at the receiving antenna is given by the formula:

V
induced

∼

ω
⁢

k
⁢

L
TX

⁢

L
RX

Based on the equation above, if the frequency of operation (ω) is increased, the respective transmitting and receiving antenna inductances required to produce a similar induced voltage is reduced, given a similar coupling factor, k. Thus, as a result, smaller inductors that require less space can be utilized for the respective antennas. For example, if the form factor, i.e., surface area of the coils is kept nearly identical having a similar coupling coefficient, a thinner receiver coil or transmitter coil may be possible by designing for a reduced receiving or transmitting inductance because of the increased operating frequency (ω).

In wearable electronics, where space is at a premium, operating at a higher frequency and tuning the respective inductors of the receiving antenna closer to the intended frequency of transmission provides the potential of increased performance, i.e., improved quality factor and increased induced voltages in a smaller form factor.

In contrast to the prior art TSMM antenna, the single-structure multi-mode (SSMM) antenna of the present disclosure provides an efficient design that enables the reception and transmission of a multitude of a non-limiting range of frequencies which includes the frequency specification of the Qi and Rezence interface standards, in addition to many other wireless electrical power transfer standards. In addition, the single structure multi-mode antenna of the present disclosure enables multiple communication based standards such as, but not limited to, near field communication (NFC), radio frequency identification (RFID), multi-mode standard transponder (MST), in addition to a host of frequency standards that operate at frequencies greater than about 400 MHz. The physical mechanism of these multiple “power” transfer and/or “communications” modes may be purely magnetic, such as via magnetic fields, electromagnetic, such as via electromagnetic waves, electrical, such as via capacitive interactions or piezoelectric action. Piezoelectric power transfer and/or communication modes would generally require a unique piezoelectric material such as barium titanate, lead zirconate titanate, or potassium niobate that is able to transduce acoustic signals to electrical signals and vice versa.

Specifically, the single-structure multi-mode (SSMM) antenna of the present disclosure facilitates either or both the transmission and reception of wirelessly transmitted electrical power and/or data. The unique design and construction of the SSMM antenna of the present disclosure, provides an antenna having optimized electrical performance in a reduced form factor.

In addition, the single structure antenna of the present disclosure may also comprise a plurality of materials such as various ferrite materials to block magnetic fields from adjacent wire strands of the plurality of coils. Thus, these magnetic blocking materials shield adjacent wire strands from the adverse effects of magnetic fields on the propagation of electrical power and/or electric signals.

Specifically, the present disclosure provides an antenna having a single coil structure in which a multitude inductor coils are electrically connected in series. Such a construction provides for an antenna having a compact design that enables adjustment or tuning of the inductance within the antenna which results in the ability to tune multiple antenna frequencies.

Turning now to the drawings, FIGS. 2, 2A, 3, 3A, 3B, 3C, 3D, 3E, 4, 4A, 9 and 11 illustrate different embodiments and configurations of a single structure multi-mode antenna of the present disclosure. FIG. 2 illustrates an embodiment of a three-terminal antenna 20 of the present disclosure. As illustrated, the antenna 20 comprises a substrate 22 on which is positioned a first, outer coil 24 and a second, interior coil 26. More specifically, both the first and second coils 24, 26 are positioned on an external surface 28 of the substrate 22.

As shown, the first outer coil 24 comprises a first electrically conductive material 30 such as a trace or filar which is positioned in a curved orientation with respect to the surface 28 of the substrate 22. In a preferred embodiment, the trace or filar 30 is positioned in a spiral or serpentine orientation with respect to the surface 28 of the substrate 22 having “N₁” number of turns. The second interior coil 26 comprises a second electrically conductive material 32 such as a trace or filar positioned in a curved orientation with respect to the surface 28 of the substrate 22. In a preferred embodiment, the second trace or filar 32 is positioned in a spiral or serpentine orientation with respect to the surface 28 of the substrate 22 having “N₂” number of turns.

In a preferred embodiment as shown in FIG. 2, the second interior coil 26 is positioned within an inner perimeter formed by the first outer coil 24. As defined herein, a “turn” is a single complete circumferential revolution of the electrically conductive filar positioned on the surface of a substrate. As illustrated in the example antenna shown in FIG. 2, the first outer coil 24 comprises 3 turns (N₁) and the second interior coil 26 comprises 14 turns (N₂). In a preferred embodiment, the first outer coil 24 may comprise from about 1 to as many as 500 or more “N₁” turns and the second interior coil 26 may comprise from about 1 to as many as 1,000 or more “N₂” turns. In a preferred embodiment, the number of “N₂” turns is greater than the number of “N₁” turns. In addition, it is not necessary for the first and second coils 24, 26 to be constructed having a discrete number of turns, the coils 24, 26 may also be constructed having a partial turn or revolution such as a half or quarter of a complete turn.

In addition, the conductive filars 30 that form the first outer inductive coil 24 have a filar width that may range from about 0.01 mm to about 20 mm. In a preferred embodiment, the width of the outer inductor coil filars 30 is constant. However, the width of the first outer inductor conductive filars 30 may vary. The conductive filars 32 that form the second interior inductive coil 26 have a preferred width that ranges from about 0.01 mm to about 20 mm. The second conductive filar 32 may also be constructed having a constant or variable width. In a preferred embodiment, the first electrically conductive filars 30 that form the first outer inductor coil 24, have a width that is greater than the width of the second electrically conductive filars 32 that form the second interior inductor coil 26. However, it is contemplated that the width of the first conductive filars 30 may be about equal to or narrower than the width of the second electrically conductive filars 32 that form the second interior inductor coil 26.

In general, the first outer inductor coil 24 contributes to the reception and/or transmission of higher frequencies in the MHz range whereas, the second interior inductor coil 26 contributes to the reception and/or transmission of frequencies in the kHz range. The increased perimeter size and typically fewer number of filar turns that comprise the first outer inductor coil 24, generally create first coil inductances in the 4.2 μH range, which, thus, provides reception and/or transmission in the MHz operating frequency range. In contrast, the increased number of filar turns and smaller coil diameter of the second interior inductor coil 26 generally create inductances in the 8.2 μH range, which provides reception and/or transmission in the kHz operating frequency range. Furthermore, by electrically connecting at least the first and second inductor coils 24, 26 in series at different locations thereof, enables the single structure antenna of the present disclosure to operate at multiple frequencies while encompassing reduced surface area and a smaller foot print.

Specifically, the single structure antenna of the present disclosure comprises a plurality of terminal connections that are strategically positioned on the first and second inductor coils 24, 26, respectively. This unique antenna design provides for a variety of tunable inductances which, in turn, provides for a variety of selectively tunable operating frequencies. In a preferred embodiment, the single structure antenna can be designed so that it can operate at multiple frequencies and multiple frequency bands anywhere between about the 1 kHz range to about the 10 GHz range. The prior art two structure antenna 10 is not capable of operating at such multiple frequencies with such a reduced foot print size.

FIG. 2 illustrates an example of a three terminal single structure antenna 20 of the present disclosure. As shown in FIG. 2, the first outer coil 24 is electrically connected in series to the second interior coil 26. This electrical connection between the two coils 24, 26 combines the inductance contributions of both coils, and portions thereof, in a reduced foot print. FIG. 2A is an electrical schematic diagram of the antenna 20 shown in FIG. 2. As shown, the antenna 20 comprises three terminals, a first terminal 34 a second terminal 36, and a third terminal 35. As illustrated, the first terminal 34 is electrically connected to the first outer inductive coil 24, the second terminal 36 is electrically connected to the second interior inductive coil 26, and the third terminal 35 is electrically connected to a second end of the first outer coil 24. Alternatively, the antenna 20 may be constructed having the first terminal 34 electrically connected to the second inductive coil 26 and the second terminal 36 electrically connected to the first inductive coil 24.

In a preferred embodiment, the antenna 20 may be constructed with an electrical switch circuit 37 that enables selection of a desired inductance and operating frequency. More specifically, the electrical switch circuit 37 enables the detection and analysis of the electrical impedance of either or combination thereof of the first and second coils 24, 26. Therefore, based on the detection and analysis of the electrical impedance, an efficient selection of the antenna's operating frequency can be achieved based on an optimized or desired electrical impedance value. In addition, the selection of the terminal connections may be based on an optimized or desired inductance value at a desired operating frequency or frequencies.

As illustrated in FIG. 2A, the switch circuit 37 is electrically connected in series between the first and second coils 24, 26. In a preferred embodiment, the switch circuit 37 enables the selection of a connection between the first and second coils 24, 26, or alternatively, a selection of either of the first or second coils 24, 26 individually. The third terminal 35 is electrically connected at point 33 which is an electrical junction between the first and second coils 24, 26.

As previously mentioned, the electrical switch circuit 37 preferably comprises at least one capacitor C₁having a first capacitance. The at least one capacitor C₁is preferably electrically connected along the third terminal 35. In addition, the switch 37 may also comprise a second capacitor C₂having a second capacitance. The second capacitor C₂is preferably connected between point 33 and the second interior coil 26. Inclusion of the at least one capacitor C₁enables the detection and analysis of the impedance of either or both coils 24, 26 at an operating frequency. In a preferred embodiment, the electrical impedance can be determined by the following equation: X=2πfL, where X is the electrical impedance of the antenna, f is the operating frequency of the antenna and L is the inductance of the antenna.

In a preferred embodiment, the substrate 22 is of a flexible form, capable of bending and mechanical flexure. The substrate 22 is preferably composed of an electrically insulating material. Examples of such insulative materials may include but are not limited to, a paper, a polymeric material such as polyimide, acrylic or Kapton, fiberglass, polyester, polyether imide, polytetrafluoroethylene, polyethylene, polyetheretherketone (PEEK), polyethylene napthalate, fluropolymers, copolymers, a ceramic material such as alumina, composites thereof, or a combination thereof. In some situations (e.g., when the antenna is constructed using insulated wire such as magnet wire/litz wire or stamped metal), the substrate may be the shielding material.

In a preferred embodiment, at least one of the first, second and third terminals 34, 36, 35 of the antenna 20 are electrically connectable to an electronic device 38. The electrical device 38 may be used to modify and/or condition the electrical power, electrical voltage, electrical current or electronic data signal received or transmitted by the antenna 20. The electrical energy received by the antenna may be used to directly power the electronic device 38. Alternatively, the electrical device 38 may be used to transmit electrical power and/or a data signal thereof. The electronic device 38 may comprise, but is not limited to, a tuning or matching circuit (not shown), a rectifier (not shown), a voltage regulator (not shown), an electrical resistance load (not shown), an electrochemical cell (not shown) or combinations thereof.

FIG. 3 illustrates an additional embodiment of a three terminal single structure antenna 40 of the present disclosure. Similar to the antenna 20 embodiment illustrated in FIG. 2, the three terminal antenna 40 comprises a first outer coil 42 that is electrically connected in series to a second interior coil 44. The electrical connection between the two coils 42, 44 combines the inductance contributions of each of the coils 42, 44 in a reduced size and surface area. The addition of a third terminal further enables the antenna 40 to be tuned to a specific frequency or multiple frequency bands. Thus, by providing multiple connection points within and between the outer and interior inductor coils 42, 44 the inductance, and thus, the receiving or transmitting frequency bands can be instantaneously adjusted without the need to add or remove inductors. The three terminal antenna design enables the first and second coils 42, 44 to be strategically connected at different locations along either or both the first and second coil 42, 44. As a result, the inductance of the antenna 40 can be modified, i.e., increased or decreased, without increasing the size of the footprint of the antenna. The antenna 40 of the present disclosure efficiently utilizes space and substrate surface area to increase and/or decrease inductance therewithin and, thus, custom tune the operating frequency or frequency band of the antenna 40.

The antenna 40 as shown in FIG. 3 comprises three terminals, a first terminal 46, a second terminal 48, and a third terminal 50, each having three respective terminal connections 52, 54, and 56. Each of the terminals is electrically connected at different terminal connection points of the antenna 40. As shown, the first terminal 46 extends from a first end 58 of a first trace 60 of the first outer coil 42. The second terminal 48 extends from a first end 62 of a second trace 64 of the second inductor 44. The third terminal 50 extends from a second end 66 of the second trace 64 of the second coil 44. Thus, the three terminals 46, 48, and 50 provide different connection points between the first and second inductor coils 42, 44 and portions thereof. Connecting the various terminals in different combinations thus provides the antenna 40 of the present disclosure with different adjustable inductances which, in turn, modifies the operating frequency or operating mode of the antenna 40. For example, by electrically connecting the first terminal 46 to the second terminal 48, a first inductance may be produced that is generally suitable for operation at a first operating frequency. Electrically connecting the first terminal 46 to the third terminal 50 produces a second inductance that is generally suitable for operation at a second operating frequency. Electrically connecting the second terminal 48 to the third terminal 50 produces a third inductance that is generally suitable for operation at a third operating frequency. Each of the inductances that are capable of being generated by the antenna of the present disclosure is preferably different from each other. Furthermore, it is contemplated that the antenna may be able to instantaneously switch from one inductance value to another, thereby instantaneously changing the antenna's operating frequency.

FIG. 3A illustrates an electrical schematic diagram of the three terminal antenna 40 illustrated in FIG. 3. As shown, connecting the first terminal 46 and the third terminal 50 provides a connection to the first outer inductor coil 42 having “N₁” number of turns. Connecting the second terminal 48 to the first terminal 46 provides a connection to the second interior inductor coil 44 having “N₂” number of turns. Lastly, establishing a connection between the second and third terminals 48, 50 provides an electrical series connection to both the first outer inductor coil 42 and the second interior inductor coil 44 having “N₁”+“N₂” turns. More specifically, FIG. 3A illustrates an embodiment in which the first inductor coil 42 is electrically connected in series with the second inductor coil 44. As shown, the first terminal 46 is electrically connected to the first end 58 of the first outer inductor coil 42. The second terminal 48 is electrically connected to the first end 62 of the second inductor coil 44 at an electrical junction 68 distal of the first inductor coil first end 58. As illustrated, the third terminal 50 is electrically connected to a second end 70 of the first inductor coil 42.

In a preferred embodiment, the three-terminal antenna design shown in FIGS. 3 and 3A enables the operation of the antenna in three different operation modes. As defined herein, an operation mode is an operating frequency band width. Such modes may include, but are not limited to the Qi, PMA and Rezence wireless standard frequencies. Table I shown below, details an example of the different terminal connection configurations and how they affect the operation mode of the antenna. More specifically, Table I illustrates various examples of how the operating frequency of the antenna may be changed by connecting various terminal connections together. It is noted that the operating frequencies detailed in Table I are examples and that the operating frequency bands may be custom tailored to meet specific requirements. Such customization can be achieved through designing each coil with a specific number of turns, a specific trace width, and terminal location points on each of the first and second coils.

TABLE I

Terminal

Mode
Operating Frequency
Connections

1
100-250 kHz (Qi and/or PMA)
1 and 2

1
6.78 MHz (A4WP)
1 and 3

2
13.56 MHz (NFC/RFID/
1 and 3

Proprietary power and data)

2
100-250 kHz (Qi and/or PMA)
2 and 3

3
250-500 kHz (PMA and/or,
2 and 3

proprietary power and data)

While FIGS. 3 and 3A illustrate a specific example of connecting three terminals to the respective ends of the first and second inductor coils 42, 44, it is further contemplated that these connections may be positioned at various electrically conductive points along the first and second conductive traces 60, 64 of the first and second inductor coils 42, 44. In addition, it is contemplated that additional terminal connections may be positioned along the first and second 42, 44 inductor coils of the antenna 40, to further provide customized inductances and, thus, provide customized operating frequencies of the antenna 40. In general, establishing an electrical connection with an inductor coil or multiple inductor coils having an increased number of turns increases the inductance that results in an antenna that more suitable to receive or transmit lower frequency signals. Likewise, establishing an electrical connection with an inductor coil or multiple inductor coils having a decreased number of turns decreases the inductance and therefore results in an antenna that is more suitable to receive or transmit higher frequency signals.

Similar to the two terminal antenna illustrated in FIGS. 2 and 2A, the three terminal antenna may be electrically connected to an electrical device 38. The electrical device 38 may be designed to condition or modify electrical power and/or an electrical signal, such as a digital data signal. Alternatively, the electrical device 38 may directly receive or transmit the electrical power and/or data signal. The electronic device 38 may comprise, but is not limited to, a tuning or matching circuit (not shown), a rectifier (not shown), a voltage regulator (not shown), an electrical resistance load (not shown), an electrochemical cell (not shown) or combinations thereof. In addition to modifying or conditioning a received electrical voltage, electrical current, or digital signal, the electronic device 38 may also be used to modify or condition an electrical voltage, electrical current, or digital signal that is being transmitted by the antenna 40.

FIGS. 3B and 3C illustrate an embodiment of a multiple layer three terminal antenna 72. In a preferred embodiment, the single structure antenna of the present disclosure may comprise a plurality of two or more substrate layers 22 that are positioned in a parallel orientation to each other. In addition, at least one electrically conductive trace is positioned along an exterior surface of the substrates that comprise the antenna 72. The filar or filars may be orientated such that at least one inductor coil is disposed along a top surface of one or more of the substrates. The substrates that comprise the antenna are preferably oriented in the same orientation such that the bottom surface of a first substrate is positioned above the top surface of a second substrate.

In addition, at least one via may be provided to establish an electrical connection between the various substrate layers. In a preferred embodiment, the at least one via provides an electrical connection between filars or portions of filars that comprise an inductor coil or coils at different substrate layers. As defined herein a “via” is an electrical connection between two or more substrate layers. A via may comprise a wire, an electrically filled through-bore or electrically conductive trace.

Specifically, FIGS. 3B and 3C illustrate the first and second layers, respectively of a two layer three terminal single structure antenna. FIG. 3B illustrates an embodiment of a first or lower layer 74 of the antenna 72 of the present disclosure. As shown, the first layer 74 comprises a first outer inductive coil 76 that is electrically connected in series to a second interior inductive coil 78.

In a preferred embodiment, as illustrated in FIG. 3B, the first terminal 46 is electrically connected in parallel to two traces or filars, thereby creating a bifilar connection 80 that comprises the first inductor coil 76. It is noted that two or more adjacent electrically conductive traces or filars that comprise an inductive coil may be connected in parallel. In general, connecting two or more adjacent traces or filars reduces electrical resistance, particularly the equivalent series resistance (ESR) of the antenna and as a result, improves the quality factor of the antenna.

As shown in FIG. 3B, the first inductor coil 76 is electrically connected in series to the second interior inductor coil 78 that is positioned within an inner perimeter formed by the first inductor coil 76. As shown, a second end 82 of the first inductor coil 76, located at an inner most end of the coil 76 is electrically connected to a first end 84 of the second inductor coil 78. The first end 84 of the interior inductor coil 78 is disposed at the end of an outer most filar track of the second inductor coil 78. The second inductor coil 78 terminates at a second inductor coil second end 86 which is disposed at an inner most location of the second inductor coil 78.

FIG. 3C illustrates an embodiment of a second upper substrate layer 88 of the antenna 72 of the present disclosure. The second layer 88 is preferably positioned directly above the first lower substrate 74. The second layer 88 comprises a third outer inductor coil 90 that is electrically connected in series to a fourth interior inductor coil 92. In a preferred embodiment, the respective first and third coils 76, 90 and the second and fourth coils 78, 92 of the first and second layers 74, 88 may be positioned about their respective substrates in a parallel relationship. In addition, the respective first and third coils 76, 90 and the second and fourth coils 78, 92 of the first and second layers 74, 88 may be in a similar position about their respective substrate surfaces and may comprise the same number of turns with similar trace widths. Alternatively, the respective first and third coils 76, 90 and the second and fourth coils 78, 92 of the first and second layers 74, 88 may be positioned at different locations relative to their specific substrate surfaces and they may have differing number of turns with differing trace widths.

Similar to the first layer 74, the first terminal 46 of the second layer 74 is electrically connected in parallel to two adjacently positioned traces or filars, thereby creating a bifilar connection at a first end 94 of the third inductor coil 90. This bifilar connection comprises the electrical trace pattern of the third inductor coil 90, extending around the third coil 90 and ending at a second end 96 thereof. Furthermore, the third inductor coil 90 is electrically connected in series to the fourth interior inductor coil 92 positioned within the inner perimeter of the third inductor coil 90 at a third inductor coil second end 96 which is disposed at an interior location of the third inductor coil 90. The fourth inductor coil 92 is electrically connected to the third inductor coil 90 at a first end 98 of the interior inductor coil which is disposed at an outer most filar track of the fourth inductor coil 92. In addition, as illustrated in FIG. 3C, the second upper layer 88 also comprises the second and third terminal connections 48, 50. In a preferred embodiment, the second terminal 48 is electrically connected at a second end 100 of the fourth inductor coil 92 positioned at an inner most location of the fourth coil 92. In addition, the length of the second terminal 48 is electrically isolated from each of the filar tracks that comprise the third and fourth inductor coils 90, 92. The third terminal 50 is provided on the second upper layer 88. As shown, the third terminal 50 is electrically connected to the bifilar track 94 that is disposed at the inner most location of the third outer inductor coil 90.

Furthermore, a via 102 or a plurality of vias 102, are preferably positioned between two or more substrate layers 74, 88 that comprise the single structure antenna 72 of the present disclosure. More preferably, the at least one via 102 provides a shunted electrical connection between different locations between the respective first and third inductor coils 76, 90 or the second and fourth inductor coils 78, 92 to minimize electrical resistance which may adversely affect electrical performance and quality factor.

In a preferred embodiment, a plurality of shunted via connections are positioned between the upper and lower layers to electrically isolate portions of the second and third terminals 48, 50, thereby enabling the terminals to “overpass” the conductive traces of the respective coils. More specifically, to create an “overpass” a plurality of vias 102 may be positioned on respective left and right sides of a trace 104 of the terminal. The plurality of vias 102 positioned on the respective left and right sides of the terminal line 104 of the terminal thus form electrical paths underneath the terminal trace 104, thereby electrically isolating the terminal trace 104 by “bypassing” the portion of conductive traces on which the terminal lead 104 is positioned. In addition, the plurality of shunted vias 102 may also create an electrical path that bypasses at least a portion of the terminal lead 104. In this embodiment, each of the plurality of vias 102 are positioned in opposition to each other on respective left and right sides of the terminal lead 104.

FIG. 3D illustrates a magnified view of an example of a plurality of shunted via connections between a portion of the first inductor coil 76 that is disposed on the lower first substrate layer 74 and the third inductor coil 90 that is disposed on the upper second substrate layer 88. As shown, a plurality of via connections is shown between inductor coils that are disposed on the respective upper and lower substrate layers 74, 88. More specifically, as shown in the embodiment of FIG. 3D, there are four vias 102 positioned along each filar tracks besides each of the respective right and left sides of the terminal line 104. In a preferred embodiment, the via connections provide a shunted electrical connection that by passes under the terminal line 104. Thus, by positioning a plurality of vias adjacent the respective sides of the terminal line 104, an electrical connection can be provided that bypasses the terminal line 104 of the terminal thereby keeping the terminal trace 104 electrically isolated from the conductive traces it passes through. Furthermore, by providing a plurality of vias 102 positioned along each of the filar tracks that comprise the inductor coil, various electrical connections can be made which can further tailor the inductance and resulting operating frequency of the single structure antenna of the present disclosure. For example, various electrically isolated terminal connections can be positioned throughout the inductor coils thus establishing further customized inductances and operating frequencies.

FIG. 3E illustrates an alternative embodiment of a single structure antenna 106 in which respective first and second inductive coils 108, 110 comprise a single filar pattern. As shown the first, second and third terminals 46, 48, and 50 are respectively connected to a single filar that comprises the first and second inductor coils 108, 110. While it is preferred to connect the respective terminals to multiple filars, such as the first terminal connection shown in FIGS. 3B and 3C, to minimize electrical resistance, it may be necessary to provide an electrical connection to a single filar to achieve a desired inductance in a relatively small space and/or surface area. In general, having an electrical parallel connection to two or more adjacently positioned filars reduces electrical resistance which in turn increases the quality factor of the antenna.

FIG. 3F illustrates a magnified view of the terminal connections illustrated in FIG. 3E. As shown, the terminal traces of the second and third terminals 48, 50 are electrically isolated as they effectively bypass over the electrically conductive the filar tracks that comprise the inductor coil. Via connections 103 provided on both sides of the respective terminal lines 104 provide an electrical connection that bypasses the terminal lines thereby electrically isolating the terminal lines from the filar lines of that comprise the inductor coil. As shown, a plurality of vias 102A are positioned on the right side of the terminal lead 104 of the third terminal 50, vias 102B are positioned to the left and right of the terminal traces 104 of respective third terminal 50 and second terminal 48 and vias 102C are positioned to the left of the terminal trace of the first terminal 48.

In addition to the two and three terminal antennas illustrated in the present application, it is further contemplated that a single structure antenna may comprise four or more terminal connections. FIG. 4 illustrates an electrical circuit diagram of an embodiment of a four terminal antenna 112 of the present disclosure. As illustrated, the first terminal 46 is electrically connected to the first end 58 of the first outer inductor coil 42. The second terminal 48 is electrically connected to the first end of the second inductor coil 44. The third terminal 50 is electrically connected to the second end 70 of the first inductor coil 42. In addition, a fourth terminal 114 is electrically connected to a second point 116 along the electrically conductive track of the first inductor coil 42. The fourth terminal connection effectively shortens the length of the first inductor coil 42 and/or the number of turns between electrical connections thereby providing an additional terminal connection which can be selected to adjust the inductance and operating frequency of the antenna.

Table II shown below, details the inductance and resulting operating frequency of an exemplar three and four terminal connection antennas illustrated in FIGS. 2, 2A, 3, 3A, 4 and 4B. It is noted that the inductance may be increased or decreased by modifying the number of turns of at least one of the first and second inductor coils.

TABLE II

Terminal

Antenna
Connection

Operating
Inductance
Quality

Config
Config
N₁
N₂
Frequency
(μH)
Factor

4 Terminal
1 and 2
3
0
6.78
MHz
0.84
>110

4 Terminal
3 and 4
0
14
100-300
kHz
6.7
>20

3 Terminal
1 and 2
3
14
6.78
MHz
0.84
>110

3 Terminal
1 and 3
3
17
100-300
kHz
7.5
~17.5

3 Terminal
2 and 3
3
14
100-300
kHz
6.7
>20

As the table above illustrates, by establishing different electrical connection points along the coils that comprise the antenna, provides for a wide range of inductances, operating frequencies and frequency bands. As shown above, by increasing or decreasing the total number of turns, i.e. by selectively connecting different locations of the electrically connected the first and second inductor coils, and portions thereof affects the resultant inductance of the antenna.

In a preferred embodiment, the electrical or electronic device 38 may be a selection circuit 118 electrically connected to the single structure antenna of the present disclosure. Specifically, the selection circuit 118 is electrically connected to at least two of the terminals that comprise the antenna. The selection circuit 118 actively monitors and measures the electrical impedance at the respective antenna terminals and combinations thereof. Thus, when the electrical impedance is measured to be at, above, or below a certain threshold electrical impedance or band of electrical impedances, the selection circuit 118 is capable of connecting or disconnecting the various terminals that comprise the antenna to achieve a desired frequency band. In a preferred embodiment, the selection circuit 118 comprises at least one capacitor having a capacitance C₃. The capacitance of the selection circuit is selected to activate a switching mechanism between antenna terminals by providing a high impedance path or a low impedance path, depending on the frequency of operation. In addition, the selection circuit 118 may also be able to actively connect and/or disconnect various regions or specific locations along the inductance coils that comprise the single structure antenna. In an embodiment, the selection circuit 118 operates by selecting an inductor coil, portion of an inductor coil, or combinations thereof, having the lowest electrical impedance. Alternatively, the selection circuit 118 may be designed to actively switch between terminals at a specific electrical impedances or range of electrical impedances. For example, the selection circuit 118 may measure the electrical impedance at various terminal connections and determine that based on the value of the capacitance C₃within the selection circuit 118 to connect terminals 1 and 3 instead of terminals 1 and 2 for example.

Consider, for example, a multi-mode antenna system wherein a first frequency mode is operating in the frequency range of f₁+/−Δf₁, and a second frequency mode is operating at f₂+/−Δf₂, wherein f₁is the resonating frequency of the first outer inductor coil, Δf₁is the bandwidth of the resonating frequency of the first outer inductor coil formed by the first terminal 46 and the third terminal 50 (FIG. 3E), f₂is the resonating frequency of the second interior inductor coil, and Δf₂is the bandwidth of the resonating frequency of the second interior inductor coil formed between the first and second terminals 46, 48 (FIG. 3E), provided the following conditions (A, B, and C) are true for the exemplar antenna.

Example Conditions:

- A. f₁≥10f₂,
- B. Δf₂≤0.5f₂
- C. Δf₁≤f₁/50

The selection circuit may be configured to select a desired antenna impedance Z₂, at a desired antenna operating frequency f. For example, given the parameter equations as shown below, where C₃is the capacitance value of the selection circuit 118 for a desired antenna operating frequency, f (e.g. f=f₁±Δf₁or f=f₂±Δf₂) and in which the impedance of the antenna is multiplied by a constant such as 1, 2, or 5. Thus, the selection circuit 118 can be designed such that the terminal connections are made at a certain impedance threshold value at a specific frequency or frequency band which may be determined by a multiplier constant.

1

2
⁢
π
⁢
f
⁢

C
3

<

Constant
×

❘
"[LeftBracketingBar]"

Z
⁢
1
⁢

or
⁢

2

❘
"[RightBracketingBar]"

In general, the greater the difference in electrical impedance, the better discrimination in coil selection, thus the multiplier constant such be selected to create a discriminating electrical impedance that may be used to modify the operating frequency of the antenna. Thus, provided a capacitance value C₃, the selection circuit may choose between the lower of the electrical resistance of the first inductor coil Z₁and the electrical resistance of the second inductor coil Z₂. In the example, if:

1

2
⁢
π
⁢
f
⁢

C
1

is lower than Z₂, the selection circuit may actively choose the terminal connections for the first inductor coil. An exemplary situation is when the higher frequency range conforms to a single mode, the Rezence wireless charging standard operating at a frequency f₁of about 6.78 MHz with a bandwidth of +/−15 kHz, while the lower frequency range conforms to two modes, i.e., the Qi standard operating between 100 kHz and 205 kHz and the PMA standard operating between 100 kHz and 350 kHz. In this case, if the first outer inductor coil is selected, then the antenna will actively receive or transmit in the Rezence mode at an operating frequency of about 6.78 MHz.

In addition to the number of turns and various lengths of the electrically conductive filars of the respective inductor coils that control the inductance and operating frequency of the antenna of the present disclosure, the quality factor of the single structure multiple mode antenna of the present disclosure can be significantly affected by the length and position of a gap 120 of space disposed between adjacent first and second inductor coils such as the first and second inductor coils 76, 78 and/or the third and fourth inductor coils 90, 92.

As will be described herein, the single structure multiple mode antenna 20, 40, 72, 106, 112 of the present disclosure is preferably designed with a high quality factor (QF) to achieve efficient reception/transfer of electrical power and/or an electrical data signal. In general, the quality factor of the antenna is increased by reducing the intrinsic resistive losses within the antenna, particularly at high operating frequencies of at least 300 kHz.

The quality factor is the ratio of energy stored by a device to the energy lost by the device. Thus, the QF of an antenna is the rate of energy loss relative to the stored energy of the antenna. A source device carrying a time-varying current, such as an antenna, possesses energy which may be divided into three components: 1) resistive energy (W_res), 2) radiative energy (W_rad), and 3) reactive energy (W_rea). In the case of antennas, energy stored is reactive energy and energy lost is resistive and radiative energies, wherein the antenna quality factor is represented by the equation Q=W_rea/(W_res+W_rad).

In near field communications, radiative and resistive energies are released by the device, in this case the antenna, to the surrounding environment. When energy must be transferred between devices having limited power stores, e.g., battery powered devices having size constraints, excessive power loss may significantly reduce the devices' performance effectiveness. As such, near-field communication devices are designed to minimize both resistive and radiative energies while maximizing reactive energy. In other words, near-field communications benefit from maximizing Q.

By example, the efficiency of energy and/or data transfer between devices in an inductively coupled system is based on the quality factor of the antenna in the transmitter (Q₁), the quality factor of the antenna in the receiver (Q₂), and the coupling coefficient between the two antennas (κ). The efficiency of the energy transfer varies according to the following relationship: effακ²Q₁Q₂. A higher quality factor indicates a lower rate of energy loss relative to the stored energy of the antenna. Conversely, a lower quality factor indicates a higher rate of energy loss relative to the stored energy of the antenna. The coupling coefficient (κ) expresses the degree of coupling that exists between two antennas.

Further, by example, the quality factor of an inductive antenna varies according to the following relationship:

Q
=

2
⁢
π
⁢
fL

R

where f is the frequency of operation, L is the inductance, and R is the total resistance (ohmic+rediative). As the quality factor is inversely proportional to the resistance, a higher resistance translates into a lower quality factor. Thus, the antenna of the present disclosure is designed to decrease the electrical resistance and, therefore, increase the quality factor.

Specifically, the single structure multiple mode antenna of the present disclosure is designed with a gap of space 120 positioned between adjacently positioned inductor coils such as the first and second inductor coils 24, 26. This gap 120 preferably reduces the proximity effect between adjacently positioned inner and outer coils, such as 76, 78 (FIG. 3B) and 90, 92 (FIG. 3C). As defined herein, “proximity effect” is the resultant increase in electrical resistance that occurs when two wires carrying alternating current, are positioned next to each other. More specifically, the proximity effect relates to the effect that one current carrying filament has on an adjacent current carrying filament when time-varying current is propagating through at least one of the conductive filaments. The magnetic field generated by one filament creates a field that opposes the current in the adjacent filament, thereby creating additional alternating current (AC) electrical resistance. This effect increases with frequency according to Faraday's law. In other words, when two electrically conductive wires are positioned next to each other, the magnetic field of one wire induces longitudinal eddy currents in the other adjacent wire. These eddy currents flow in long loops along the wire in the opposite direction as the main current. Thus, these eddy currents reinforce the main current on the side facing away from the first wire, and oppose the main current on the side facing the first wire. The net effect is a redistribution of the current in the cross section of the wire into a thin strip on the side facing away from the other wire. Since the current is concentrated into a smaller area of the wire, the resistance is increased.

The proximity effect has a significant effect on the quality factor of the antenna design. The applicants have discovered that the proximity effect can be greatly reduced by increasing the gap or distance 120 between the first outer and second interior inductor coils. However, increasing the gap 120 between these coils such that the proximity effect is negligible appreciably increases the foot print of the antenna which is not desired.

Therefore, a balance between the strength of the proximity effect and its effect on the quality factor and foot print size must be optimally achieved. In general, the applicants have discovered that by providing the gap 120 having a distance of about 0.2 mm reduces the magnetic field strength by about 50%, and designing the gap 120 with a distance of about 1 mm reduces the magnetic field strength by about 90%. It is contemplated that the gap 120 may range from about 0.05 mm to about 10 mm.

Another important consideration is the operating frequency of the antenna. In general, AC electrical resistance increases with increasing magnetic field strength. This increase in AC electrical resistance is about proportional to the magnetic field strength. This is due to the generally increased proximity effect at increased operating frequencies. In general, the increase in proximity effect can be mathematically represented by the strength of the magnetic field H of an adjacent filar multiplied by the operating frequency.

For example, to obtain a similarly equal reduction of proximity effect for a first antenna operating at 6.78 MHz in comparison to a second antenna operating at 200 kHz, the magnetic field strength generated by the first antenna is required to be reduced by about a factor of 34 (6.78 Mhz/200 kHz). Therefore, to obtain a similar reduction in AC electrical resistance due to the proximity effect, between the first antenna operating at 6.78 MHz and the second antenna operating at 200 kHz, would thus require a gap of about 0.2 mm between adjacent coil traces for the second antenna operating at 200 kHz, and a gap greater than 5 mm between adjacent coil traces for the first antenna operating at 6.78 MHz.

The applicants have thus discovered that designing the gap 120 having a dimension of 0.5 mm, or greater, between the first outer and second interior coils significantly reduces the proximity effect to a negligible amount for frequencies between about 100 to about 200 kHz. Furthermore, the applicants have discovered that designing the gap 120 having a distance of about 1 mm for frequencies between about 200 to about 400 kHz, or greater, is more preferred. In some cases, where the overall allowable surface area is large, for example, when the total number of turns of the first outer and second interior inductor coils is greater than 100 and the frequency is around 6.78 MHz to 13.56 MHz, this distance can be as great as 10 mm. In general, a gap distance 120 of about 10 mm effectively reduces the magnetic field strength and the proximity effect by about 99 percent.

Table III shown below, illustrates the effect of the gap size on the electrical resistance and resulting quality factor. Specifically, examples 1-4 are of a three terminal single structure multi-mode antenna having different gap sizes between the first outer and second interior coils. As illustrated in the table, increasing the size of the gap to about 1.8 mm, increases the quality factor by about 35% in comparison to a gap size of 0.2 mm of the antenna constructed in example 4. If a larger footprint is possible for the entire antenna structure, this gap size may be further increased greater than 5 mm which results in an increase in quality factor of about 42% in comparison to the example 4 antenna which constructed with a gap size of about 0.2 mm.

For example, a system with a coupling coefficient of about 0.05 for a system operating at 6.78 MHz, and using the same coil configuration for the respective receiving and transmitting antennas with a 1.8 mm gap will yield an antenna to antenna efficiency improvement of about 16%. In addition, using a gap size greater than 5 mm would yield an antenna to antenna efficiency improvement of about 18% given the equation below where K is the coupling coefficient between a transmitting and receiving antenna, Q₁is the quality factor of the receiving antenna, and Q₂is the quality factor of the transmitting antenna. As defined herein, “antenna to antenna efficiency” is the percentage of electrical energy received by a receiving antenna that was originally transmitted by a corresponding transmitting antenna.

Eff
=

κ
2

⁢

Q
1

⁢

Q
2

(

1
+

1
+

(

κ
2

⁢

Q
1

⁢

Q
2

)

)

2

TABLE III

Freq.
Inductance
Resistance
Quality

Example
Gap Size
(MHz)
(μH)
(ohms)
Factor

1
>5.0 mm
6.78
3.1
1.30
101.6

2
1.8 mm
6.78
3.1
1.37
96.4

3
1.0 mm
6.78
3.1
1.57
84.1

4
0.2 mm
6.78
3.1
1.85
71.4

It is important to note that the magnetic field strength is directly proportional to the strength of the electrical current being propagated through an adjacent filar. For example, given the same operating frequency, the strength of the proximity effect generated from a filar with 1A of electrical current propagated therewithin is about 100 times greater than if the electrical current is at 10 mA.

FIG. 5 illustrates an embodiment of an inductor coil 121 which comprises a conductive filar 123 having a variable filar width. As shown, at least one of the inductor coils that comprise an antenna may be constructed having a filar width that ranges from about 5 mm to about 0.01 mm, more preferably from 0.55 mm to about 0.2 mm. In the preferred embodiment shown, the inductor coil is constructed having an outer filar width at a first coil end 122 that ranges from about 10 mm to about 1 mm that progressively becomes narrow as the filar extends towards the center of the inductor 121. In a preferred embodiment, the filar width at the second end 124 may range from about 5 mm to about 0.01 mm. Such thinning of the filar width is desirous to provide an additional number of turns within a smaller surface area, thereby leading to an inductance value that is higher than what would have been achieved with wider traces for all turns. Furthermore, increasing the number of turns reduces the cross-sectional area of the filament utilized by the current due to the net proximity effects of the multitude of filaments. Therefore, it is possible that a wide trace may have regions through which the current density is significantly reduced. By designing the coil in a manner of reducing the trace widths, the area utilization is maximized. Utilization of cross-sectional area is reduced due to proximity effect with increased frequency and a greater number of traces.

Constructing a coil with variable trace widths can significantly increase the inductance of the antenna. For example, two antennas having the same coil outer dimension of 34.5 mm×27 mm and an inner dimension of 15.4 mm×7.9 mm were constructed. The first antenna was constructed with 13 turns at a constant trace width of about 0.55 mm and a constant gap with between traces of about 0.2 mm. In comparison, the second antenna coil was constructed with 13 turns and a constant gap width of about 0.2 mm between adjacent traces of the coil. However, the second antenna was also constructed having a variable trace width that ranged from 0.55 mm to about 0.2 mm in the interior of the coil. The inductance of the antenna of design 1 having a constant trace width was measured to be about 4.2 μH. In contrast, the inductance of the antenna of design 2 with the variable trace width was measured to be about 8.2 μH, about double the inductance of the antenna of the first design with the same overall dimensions.

In a preferred embodiment, the quality factor may also be increased by incorporating various materials or structures that prevent or block the magnetic fields that cause the proximity effect that thus results in increased electrical resistance of adjoining conductive filars and ultimately results in a decreased quality factor. One such shielding material are ferrite materials which have a high permeability that effectively shields inductor coils from magnetic fields generated from an adjacent inductor coil or coils. Thus, by shielding the inductive coil from the magnetic field generated from another coil, reduces the proximity effect and, thus, increases the quality factor of the antenna.

The shielding material preferably has the primary function of providing a low reluctance path to magnetic field lines thereby reducing the interaction of the magnetic fields with other metallic objects, especially objects (e.g. batteries, circuit boards) placed behind the coil assembly. A second function of the shielding material is preferably to boost the inductance of the coil and, simultaneously, to increase the coupling between the transmitter coil assembly and the receiver coil assembly. The latter directly affects the efficiency of power transfer. The third ancillary benefit is that it may also improve the Quality Factor of the coil antenna if the loss tangent of the magnetic material is sufficiently small. As defined herein, “reluctance” is the resistance to a magnetic flux.

FIGS. 6A, 6B, 6C, 6D, and 6E are cross-sectional views illustrating various embodiments in which an inductor coil having an electrically conductive trace 30, 32 of a single structure multi-mode antenna of the present disclosure may be constructed using materials that shield the conductive traces, i.e., wires of the coils 24, 26 from magnetic fields. Such shielding materials may include, but are not limited to, zinc comprising ferrite materials such as manganese-zinc, nickel-zinc, copper-zinc, magnesium-zinc, and combinations thereof. These and other ferrite material formulations may be incorporated within a polymeric material matrix so as to form a flexible ferrite substrate. Examples of such materials may include but are not limited to, FFSR and FFSX series ferrite materials manufactured by Kitagawa Industries America, Inc. of San Jose California and Flux Field Directional RFIC material, manufactured by 3M™ Corporation of Minneapolis MN.

As shown in the various embodiments, three different such materials, a first material 126, a second material 128 and a third material 132, each having a different permeability, loss tangent, and/or magnetic flux saturation density may be used in the construction of the single structure antenna of the present disclosure. In a preferred embodiment, the first material 126 may comprise at least one of the FFSX series of ferrite materials having a permeability of about 100 to about 120 across a frequency range of at least 100 kHz to 7 MHz. The second material 128 may comprise the RFIC ferrite material having a permeability of about 40 to about 60, and the third material 130 may also comprise a ferrite material or combinations thereof, as previously mentioned. In a preferred embodiment, the first 126, second 128, or third 130 materials may comprise a permeability greater than 40. More preferably, the first 126, second 128, or third 130 materials may comprise a permeability greater than 100. The magnetic flux saturation density (Bsat) is at least 380 mT.

FIG. 6A shows an embodiment in which the conductive segments 30, 32 are positioned directly on an exterior surface of the ferrite materials. As shown, the first and second ferrite materials 126, 128 serve as substrate layers on which the conductive traces 30, 32 are positioned. The third ferrite material 130 is preferably positioned within a central location between the coil winding. Note that each conductive segment 30, 32 could represent multiple traces of the coil turns. Specifically, as shown, first and second outer segments 131, 135 of the conductive traces 30, 32 are positioned directly on the surface of a first layer of the first ferrite material 126 and the third and fourth inner segments 137, 139 of the conductive trace 30, 32 are positioned directly on the surface of a second layer of the second ferrite material 128. The second layer of the second ferrite material 128 is positioned on top of the first layer of the first ferrite material 126. A third layer of the third ferrite material 130 is positioned directly on the second layer of the second ferrite material 128. In a preferred embodiment, the first, second and third layers of the different ferrite materials 126, 128, and 130 are positioned such that magnetic fields 132 generated by the conductive trace 30, 32 are absorbed by the ferrite materials. Furthermore, the selection of the ferrite material may be based on the material used to construct the conductive lines as well as the amount of the current or voltage flowing therethrough.

In a preferred embodiment, the various shielding materials and structures could be used to create a hybrid shielding embodiment. In a hybrid shielding embodiment, the various shielding materials are strategically positioned to improve the performance of the multiple inductor coils which resonate at differing frequencies. Thus, the shielding materials are positioned to enhance the multi-mode operation of the antenna 10. For example, utilizing a ferrite material having an increased permeability of about 100 to 120, such as the FFSX series material may be used to optimally shield a coil resonating at 6.78 MHz without degrading the performance of the other coil resonating at a lower frequency range of 100 kHz to about 500 kHz. Likewise, utilization of a ferrite material having a lower permeability such as from about 40 to about 60, like the RFIC material, is preferred because it enhances operation of a coil resonating in the lower kHz frequency region without degrading performance of the higher MHz resonating coil.

In addition to the specific shielding material, the positioning of the shielding material is also important to the optimal operation of the multi-mode single structure antenna of the present disclosure. For example, with reference to FIGS. 6A through 6E, it may be preferred to position the higher permeability ferrite material near the higher resonating coil, such as the relative location of the first material 126 as shown in FIGS. 6A-6E. Similarly, it may be beneficial to position the lower permeability material near the coil that is resonating in the kHz range such as the location of the second material 128 The third material 130 could be a material that has similar material properties as the second material 128 or, alternatively, the third material 130 could be a ferrite material that has a high magnetic saturation that preserves the magnetic performance of the other materials in the presence of a transmitting that comprise a magnet; it also acts as an attractor to help affixing to transmitting coils that comprise a magnet.

FIG. 6B illustrates a different embodiment of the construction of the antenna of the present disclosure in which the second ferrite material 128 is positioned within a cavity formed within the first material 126. In addition, the height of the second ferrite material layer 128 is greater than the height of the first layer of the first ferrite material 126.

FIG. 6C illustrates another alternative embodiment in which the second ferrite material 128 is positioned within a cavity of the first ferrite material 126. However, in contrast to the embodiments shown ion FIGS. 6A and 6B, the height of the respective first and second ferrite material layers are about the same. FIG. 6D shows yet another embodiment in which the third ferrite material 130 may be positioned within a second cavity positioned within the second material layer 128. In addition, the second material 128 is positioned within the first cavity formed within the first layer of the first material 126. Lastly, FIG. 6E illustrates a fourth embodiment in which all three materials 126, 128 and 130 are positioned such that they are of about the same height. Specifically as shown, the third material 130 is positioned within the second cavity of the second material layer 128, the second material 128 is positioned within the first cavity of the first material layer 126 with all three material layers 126, 128, 130 being of about equal height. Therefore, the various layers of ferrite material may be positioned at different heights relative to each other such that magnetic fields 132 generated by adjacent conductive lines are optimally adsorbed by the ferrite materials.

In addition to utilizing three ferrite materials as previously discussed, it is contemplated that mixtures or compounds of various ferrite materials may be used to further custom tailor the desired permeability. Furthermore, the various layers may be composed of ferrite material mixtures and alloys. It is also noted that FIGS. 6A-6C represents specific embodiments in which ferrite materials may be positioned within the structure of the antenna of the present disclosure. It is contemplated that the various first, second, and third ferrite materials 126, 128, 130 can be interchangeably positioned throughout the structure of the antenna to custom tailor a desired response or create a specific magnetic field profile.

It will be appreciated that the multi-mode single structure antenna of the present application may be formed or made by any suitable techniques and with any suitable materials. For example, the antenna coils may comprise suitable metals or metal containing compounds and/or composites, conductive polymers, conductive inks, solders, wire, fiber, filaments, ribbon, layered metal combinations and combinations thereof be used as conductive materials. Suitable fabrication techniques may be used to place conductors on/in a substrate, including, but not limited to, printing techniques, photolithography techniques, chemical or laser etching techniques, laser cladding, laser cutting, physical or chemical vapor deposition, electrochemical deposition, molecular beam epitaxy, atomic layer deposition, stamping, chemical processing, and combinations thereof. It may also be suitable to fabricate the multi-mode single-structure antenna with wire-winding techniques leveraging magnet wires, coated wires, litz wires or other wires used by those skilled in the art. Electrical property enhancement, i.e., enhancement of electrical conductivity and substrate dielectric constant may also be used to achieve the desired properties for a specific application. For example, enhancement of electrical conductivity may be achieved through ion implantation, doping, furnace annealing, rapid thermal annealing, UV processing and combinations thereof.

FIG. 7 illustrates a flow chart illustrating an embodiment of a method of fabricating a single structure multi-mode antenna of the present disclosure. As shown in the flow chart, in a first step 200 a substrate 22 may be provided. In a second step 202 the first coil 24 is formed. The first coil 24 may be formed on a surface 28 of a substrate 22 or alternatively, the first coil 24 may be formed without a substrate 22 using at least any of the fabrication techniques previously discussed. In a third step 204, the second coil 26 is formed such that is electrically connected to the first coil 24. Like the previous step 202, the second coil 26 may be formed on a surface 28 of the substrate 22 or alternatively, the second coil 26 may be formed without a substrate 22 using at least any of the fabrication techniques previously discussed. Alternatively, the first and second coils 24, 26 may be formed such that they are contactable to a surface 28 of a substrate 22. In this case, the first and second coils 24, 26 are removably contactable to the surface 28 of a substrate 22. For example, the substrate 22 may provide a temporary mechanical support for the antenna.

After the first and second coils 24, 26 have been formed, either with or without a substrate 22, at least one terminal is electrically connected to at least one of the first and second coils 24, 26 (step 206). In an optional fourth step 206, magnetic shielding materials may be incorporated within the structure of the antenna. In a fifth step 208, at least one terminal is electrically connected to at least one of the first and second coils 24, 26. In an optional sixth step 210, a selection circuit 118 may be electrically connected to at least one of the terminals or at least one of the first and second coils 24, 26. In addition, or in lieu of a selection circuit, an electrical switch 37 may be electrically connected to at least one of the first and second coils 24, 26 or at least one terminal.

FIGS. 8A-8C illustrate various embodiments of magnetic field intensity profiles as a function of the number of turns that comprise the coil of the antenna of the present disclosure. As illustrated, in general, modifying the number of turns of the inductor affects the shape and profile of the intensity of the magnetic field. This ability to modify the position and/or strength of the magnetic field strength that is generated by the antenna can be desirable in optimizing data and energy transfer. In a preferred embodiment the strength and profile of the magnetic field can be custom tailored to meet the dimensions of various electronic devices. For example, by modifying the number of coils and/or position of magnetic shielding materials that comprise the single structure antenna of the present disclosure, the intensity profile of the magnetic fields that is generated by the antenna can be modified. It is noted that all the magnetic intensity profiles 8A-8C where taken of single structure antennas having an outer coil width dimension of about 150 mm and an outer coil length dimension of about 90 mm. In addition, the profile magnetic field measurements were taken from about 8 mm away from the outer surface of the respective antennas. A relative intensity scale lies along the right side of each of the plots FIGS. 8A-8C. As indicated by the intensity scale, the strongest magnetic field intensity has a relative intensity of about 1 and is graphically represented having the darkest shade of black. The weakest magnetic field strength has a relative intensity of about 0.1 and is shown having the lightest shade of grey.

FIG. 8A illustrates an embodiment of a magnetic field intensity profile taken of a single structure antenna comprising one outer coil having one turn. The magnetic field intensity is greatest along the outer perimeter of the coil as illustrated by the darker shades of black which represent the strongest magnetic field intensity. While the strongest magnetic field intensities are along the outer perimeter, the weakest magnetic field intensity, represented by the lighter shade of grey, lies in the central area formed within the perimeter of the coil. Thus, this embodiment is optimally configured for wireless energy transfer along the outer perimeter of the antenna.

FIG. 8B illustrates an embodiment of a magnetic field intensity profile taken of a single structure antenna comprising a coil having two turns. As shown, the greatest magnetic field intensity lies more along an inner portion of the coil as compared to the field magnetic field intensity profile of a coil having one turn as shown in FIG. 8A. The weakest field intensities of the two turn coil, shown by the lighter shade of grey, lie along the outer perimeter of the second turn of the coil which is positioned towards the interior of the antenna. In comparison to the coil having one turn as illustrated in FIG. 8A, the magnetic field along the central area of the antenna comprising a coil having two turns has an overall increased magnetic field. Thus, as shown, adding an additional interior turn moves the greatest field intensities closer to the middle of the antenna.

FIG. 8C illustrates an embodiment of a magnetic field intensity profile taken of a single structure antenna comprising a coil having three turns, a first outer turn, a second inner turn and a third inner most turn. Similar to the antenna comprising a coil with two turns, the magnetic field intensity of the three turn coil antenna shown in FIG. 8C is the strongest, along the inner perimeter of the third innermost coil and central area of the antenna. Thus, the antenna comprising a coil having three turns has the strongest magnetic field in general in the central area of the antenna. In addition, the respective corner locations of the second inner turn of the coil also has increased magnetic field intensity. Therefore, such an antenna with a three turn coil is optimally designed to transfer electrical power and data in the central area of the antenna.

FIG. 9 illustrates a further embodiment of an antenna 140 of the present disclosure of a one piece construction having a unitary antenna body. As illustrated, the antenna 140 is preferably formed from one piece of wire or filament 142 that is formed into the shape of the unitary body antenna 140 extending from a first wire end 149 to a second wire end 153. In a preferred embodiment, the antenna 140 may be formed by a stamping process in which the electrically conductive material is formed together in a mold and die stamp forming process using a metal blank. In a preferred embodiment, the metal blank is positioned between the mold and die. The die is pressed against the metal blank within the mold thus forming the antenna body 140. In addition, the electrically conductive material that forms the unitary antenna body may be a metal bar, wire, or filament that is stamped out of a sheet of metal. Alternatively, antenna 140 may be formed by a wound wire process whereby the unitary body of the antenna 140 is formed from a single wire that is curved or wound into the desired shape of the antenna 140 comprising a plurality of turns.

The antenna 140 is preferably formed of a continuous wire form having multiple electrical connection points 148, 150, 152 that are disposed along various portions of the wire 142 of the antenna 140. The plurality of electrical connection points 148, 150, 152 or electrical “taps” create multiple inductor coils having different inductances that comprise the antenna 140 of the present disclosure.

As illustrated in FIG. 9, a first electrical connection point 148 that is disposed at the first end 149 of the wire 142 of the antenna 140 serves as the common electrical connection. A second electrical connection point 150 is positioned along the third turn of the antenna 140 serves as the “low” inductance electrical connection. A third electrical connection point 152 is disposed at the second end 153 of the antenna 140 serves as the “high” inductance electrical connection of the antenna 140. In an embodiment, terminal leads 154, 156, 158, such as electrically conductive wires, may be attached to these electrical connection points to create antenna terminals. Thus, as shown, the first electrical connection point 148 may serve as the first terminal 34, the third electrical connection point 152 may serve as the second terminal 36 and the second electrical connection point 150 may serve as the third terminal 35. Furthermore, the various first, second and third electrical connection points 148, 150, 152 form the multiple inductor coils of the antenna 140. As illustrated, a first outer inductor coil portion 144 having N₁number of turns is disposed between the first and second electrical connection points 148, 150 and a second inductor coil portion 146 having N₂number of turns is disposed between the second and third electrical connection points 150, 152. Similar to the previous single structure antenna embodiments, the unitary body antenna 140 may comprises more than three terminal connections which can be electrically connected to generate a multitude of operating frequencies and/or inductances. In addition, a turn gap 161 may be positioned between adjacent turns of the first and second inductor coils portions 144, 146. Specifically, the turn gap 161 is a space disposed between adjacent wires 142 of the antenna 140. In a preferred embodiment, the turn gap 161 may extend from about 0.1 mm to about 50 mm.

Preferably, the unitary body antenna 140 illustrated in FIG. 9 is self-standing and does not require the support of a substrate. However, it is contemplated that such an antenna structure may be contactable to a substrate surface. Substrates may include, but are not limited to, a dielectric material and/or a magnetic field blocking material such as a ferrite material as previously discussed. In addition, such an antenna construct may be incorporated within an article of clothing, furniture, an electrical appliance or a vehicle.