COMBINATION ANTENNA

Description

TECHNICAL FIELD

[0001] Example embodiments described herein relate to near field antennas in combination with far field antennas.BACKGROUND

[0002] US2012 / 0231732 A1 (Kerselaers) provides a pair of RF radios and a pair of 'magnetic induction radios'. Each RF radio receives signals, and is located with one of the magnetic induction radios. The magnetic induction radios communicate with other processing circuitry, which is provided for selecting the higher quality baseband stream at any given point in time, from the two signals received by the RF radios. US2014 / 0184462 A1 (Yosui) provides a structure comprising a first coil conductor and a second coil conductor. A magnetic layer lies between the first coil conductor and the second coil conductor. The directions of flux from the first coil conductor and the second coil conductor oppose each other. The structure provides an RFID antenna. US2013 / 0119924 A1 (Kasturi et al.) provides an antenna. One embodiment of US'924 places two coils on a charging surface. An outer antenna is arranged to transmit. A passive antenna with passive circuit components is arranged on the charging surface within the perimeter of the outer antenna. The passive antenna may ensure a more uniform field distribution at a fundamental frequency.SUMMARY

[0003] A brief summary of various embodiments is presented below. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various embodiments, but not to limit the scope of the embodiments described herein. Detailed descriptions of embodiments adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections.

[0004] According to one embodiment, there is provided a pair of earpieces having the features of appended claim 1.

[0005] The RF antenna may be cylindrical. The MI antenna may be cylindrical.

[0006] The RF antenna may include a dielectric layer disposed between the MI antenna and the first conductor plate. The electrically conductive inductive wire may be arranged within the antenna body in an unbalanced way. The apparatus may include a first connection port connected to the RF antenna and a second connection port connected to the MI antenna.

[0007] The electronic circuit may transmit audio through the MI antenna to a portion of a user's body.

[0008] The pair of earpieces may each include a first and a second feeding connection, wherein both feeding connections are configured to electrically connect to a signal processing device for processing an electrical signal received or to be transmitted by the antenna.

[0009] A maximum dimension of the antenna may be less than or equal to half a wavelength of a highest operating frequency of the pair of earpieces.

[0010] The pair of earpieces may each include a receiver or transmitter unit and a matching unit connected between the receiver or transmitter unit and the antenna feeding connections of the RF antenna, the matching unit being adapted to substantially match the impedance of the RF antenna to the impedance of the receiver or transmitter unit.

[0011] The pair of earpieces may be a pair of hearing aids.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments discussed herein are described in more detail and by way of non-limiting examples with reference to the accompanying drawings, wherein: FIG. 1 illustrates different regions around an antenna system of an example embodiment; FIG. 2 illustrates a magnetic antenna of an example embodiment; FIG. 3 illustrates an antenna system according to an example embodiment; FIG. 4 illustrates input return loss when the RF antenna port was not matched to 50 Ohm or not 'tuned' of an example embodiment; FIG. 5 illustrates input return loss when the RF antenna port is matched to 50 Ohm or 'tuned' of an example embodiment; FIG. 6 illustrates a table of input return loss and input impedance measurements of the antenna of this invention in 2.4-2.5GHz in different cases of an example embodiment; and FIG. 7 illustrates a block diagram comprised of a radio IC connected to the proposed new antenna system in an example hearing aid of an example embodiment. DETAILED DESCRIPTION

[0013] Reference is made herein to the attached drawings. Like reference numerals are used throughout the drawings to depict like or similar elements described herein.

[0014] Example embodiments described herein provide a communication antenna apparatus that may generate and receive magnetic induction (MI) fields having inductive coupling characteristics in a near-field region in combination with generation and reception of electro-magnetic (EM) waves in a far-field or RF region.

[0015] Wireless communications exist in a near-field region and in a far-field region. In a far-field region, information may be transferred through radiation of EM waves. There are alternatives to using EM waves for applications using short range communication. When communication over very short distances is required there are alternatives to using EM transmission within close proximities of a transmitter or receiver.

[0016] MI communication maybe an efficient technique for short range communication. In MI communication, amplitudes of near-field waves tend to decrease faster than amplitudes of far-field electromagnetic waves. A near-field may decrease faster than electromagnetic waves as it travels through a communication channel. These and other characteristics may result in a limited communication range.

[0017] While far-field may refer to a region around a radiating antenna in which electro-magnetic waves are radiated into space, the term near-field may describe a region close to a transmitting antenna in which non-radiating magnetic waves exist.

[0018] A boundary between the near-field and far-field region may not be fixed and the boundary may change with operating frequency. The boundary between a near-field and far-field region may be defined using transmission range, wave impedance or phase variation of radiation.

[0019] An antenna system according to example embodiments may be used for body and other near field applications in the consumer lifestyle and healthcare area. A combination antenna system may be integrated into portable products attached to or adjacent the human body. Example apparatuses may include hearing aids, ear buds, headphones, and behind-the-ear hearing aids.

[0020] An antenna system of example embodiments described herein may be used in systems such as described for example in patent application US20120231732A1.

[0021] According to the invention, antenna diversity is achieved using a separate antenna in each of two sub-units or earpieces, one sub-unit for each ear. A sub-unit may be a hearing device 711 as illustrated in FIG. 7 and described herein. Separate sub-unit antennas communicates with a communication device by wireless radio frequency (RF) transmission using EM waves to receive a best or clearest signal in either of the two earpieces. Upon detecting a sound, one sub-unit may be obstructed and not receive a clear signal. Once a determined clearest signal is received in one of the two sub-units, the clearer audio transmission is communicated from one sub-unit to another by way of MI such that a user may hear the clearest transmission in both ears.

[0022] The combination antenna according to embodiments may support near-field diversity with an MI link between two hearing aids using an incorporated MI ferrite antenna into an RF antenna structuredescribed herein.

[0023] The combination antenna system of example embodiments described herein may combine two structures. A first structure includes a magnetic coil. A second structure may include an antenna design for an RF antenna for example as described in patent application number US20130257676A1.

[0024] The RF antenna structure in the combination antenna systemmay collect RF information from a communication device located away from a body of a person or entity using a hearing apparatus with the combination antenna housed therein.

[0025] Inductive coupling is a method that may be used in hearing aids for wireless audio communication. Using inductive coupling, a relatively large voltage, which may be 12V AC, may be imposed upon a coil that generates a magnetic field as a result thereof.

[0026] Within a short range of a first coil of an antenna that is positioned in or near a first ear, from a few centimeters to 1 meter, a magnetic field may be induced in a second coilin a second antenna positioned in or near a second ear, other part of the body, or within close proximity to establish short range communicationthere between.

[0027] Radios and other electronic devices communicating in this manner may thus use MI to establish a wireless link. The MI field is a non-propagating near field that has a very high roll-off behavior, losing field strength as a function of distance from the antenna.

[0028] To establish communication across a longer range, for instance greater than 1 meter, systems may use a radio or antenna module that works with EM radiation. Electromagnetic waves are able to propagate over large distances and the power rolls off as the inverse of the square of the distance from the source.

[0029] FIG. 1 illustrates different regions around an antenna of example embodiments described herein. Two main regions are near-field 110 and far-field 120. In a far-field region 120, a combination of electric and magnetic waves propagates as electromagnetic waves. An electromagnetic wave includes an electric field and a magnetic field, which are perpendicular to each other and to the direction of propagation.

[0030] As illustrated in FIG. 1, the near-field region 110 may include two sub-regions: a reactive region 112 and a radiating region 114. In the radiating region 114, an angular field distribution depends on distance, while in the reactive zone 112, energy is stored and not radiated. A precise boundary between these two regions may be determined based on the specific application.

[0031] Communication in the near-field may occur through the use of an electric field or a magnetic field. Example embodiments described hereindiscuss near field communication using magnetic induction fields.

[0032] FIG. 2 illustrates a magnetic induction antenna 200 of an example embodiment. This type of antenna may be used in MI based hearing aids. As illustrated in FIG. 2, copper wires 230, known as copper windings, may be wound around a cylindrical volume 220. When an alternating current is passed through the windings 230, an electromagnetic field is generated. A ferrite core may be inserted as the cylindrical volume 220 within the windings 230. A generated magnetic field in a transmit mode may be increased by having the ferrite core as the cylindrical volume 220. Connection port wires of the coil antenna 200 are shown at position 210. The connection wires may connect to interface circuitry to send and receive audio and information through the MI antenna 200.

[0033] FIG. 3 illustrates an antenna system 300 according to an example embodiment in conjunction with FIG. 2. The antenna system 300 includes a combination of an RF antenna structure 340 and the magnetic antenna 200 that includes the ferrite core 220 and windings 230. For example, the RF antenna 340 may be constructed in a similar manner to that described in patent application US 2013 / 0257676A1.

[0034] RF antenna 350may be formed by a hollow antenna body dielectric cylindrical tube, support body, or container 340 in which two opposing conducting circular surface plates315 and 325 are placed as antenna elements at one end and an opposing end of the cylindrical container 340. Along the body of the cylindrical tube 340 such as along or within an outside wall thereof, an inductive wire or filament 335 is formed that connects the top plate and bottom plates 315 and 325 respectively.

[0035] The magnetic antenna 200 including a ferrite core 220 and copper windings 230 may be formed of various sizes to meet various applications, likewise as may the RF antenna structure 350.

[0036] When an alternating current passes through the wire 335 a distributed inductance together with the capacitance formed by the two antenna elements 315, 325 and the insulating cylindrical tube 340, resonate at a frequency band of operation.

[0037] Feeding port connections 370 may be connected to the inductive wire 335 in an unbalanced manner, encircling close to half of the cylindrical tube 340. Feeding port connections 210 of ferrite core 220 may pass through port holes 375, 380 of the antenna system 300 to connect to integrated circuitry. The ferrite coil 230 is inserted so as to not contact the cylinder tube 340 at the conducting circular surfaces 315 or 325. A dielectric such as air, foam or solid material may separate the ferrite core 220 from the antenna plates 315 and 325.

[0038] The connection ports 370 are positioned more towards one antenna plate than another. This allows current flow to be different through one plate or the other. Example embodiments are not limited thereto. Alternatively, port connections 370 may be placed equidistant from a center of the tube 340 to allow current flow to be uniform through the RF antenna 350. Also, filament 335 maybe wound totally around the cylindrical tube 340 to increase the inductance thereof.

[0039] Methods of forming and testing the combination antenna apparatus will now be described. In order to test whether the performance of the RF antenna 350 would be affected by insertion there into of the ferrite coil 200. A proof-of-concept of the far-field antenna structure 350 was configured in the 2.5GHz range with an example height of the cylindrical tube 340 of 7mm, an outer diameter of 3.8mm, and an inner diameter of 2mm. The tubing may be made from Lowdensity polyethylene (LDPE) to achieve a desired dielectric constant and loss tangent characteristic thereof. A maximum dimension of the combination antenna apparatus may be less than or equal to half the wavelength of a highest frequency of the apparatus.

[0040] As described herein, the ferrite volume 220 and coil 230 for a near-field MI antenna 200 may be incorporated in the far-field antenna structure 350. The ferrite coil 200 including volume 220 may have a diameter of 1.8mm, a length of 6mm and inductance of 3.6uH.

[0041] To verify the desired effects, performance characteristics of the combination antenna were measured. Measurements included a magnetic induction performance and RF performance of the antennae 200 and 300.

[0042] One portion of the test involved measuring the performance of the ferrite core 200 on its own and comparing the performance characteristics of the ferrite core 200 with the combination antenna 300 to determine the differences, if any, of the MI near field transmission characteristics.

[0043] On its own, an inductance value of the original ferrite 200 was 3.6uH. The series resistance Rs=0.56 Ohm at 1kHz. The sensitivity of the original ferrite core 200 at 10MHz was 40uV for a magnetic field strength (H) of 1mA / m.

[0044] Incorporated into the RF antenna 350, the inductance value of the ferrite 200 was 3.8uH, the series resistance Rs=0.57Ohm at 1kHz. The sensitivity of the incorporated ferrite core 200 at 10MHz is 41.3uV for H=1mA / m with the RF antenna port open or short circuited.

[0045] From these measurements one may observe that the MI performance of the ferrite core coil 200 was not altered significantly by incorporating the MI antenna 200 into the RF antenna350. Therefore, in combination, the incorporated MI antenna may be used effectively for near-field communications.

[0046] FIGS. 4-6 illustrate results from tests conducted with the antenna system of embodiments described herein attached to a SPEAG SAM head model such as SAM-V4-SBSE. A series of tests was performed to determine RF performance evaluated by means of the input impedance of example embodiments.

[0047] FIG.4 illustrates the input return loss (S 11 ) when the RF antenna port was not matched to 50 Ohm or not 'tuned' to the head model. The input return loss of the RF antenna port relates to the input impedanceofthat port. The formulas to convert input return loss, S 11 , to input impedance, Z in , or vice versa are, Z in = Z 0 1 + S 11 1 − S 11 and S 11 = Z in + Z 0 Z in − Z 0 with, Z 0 , characteristic impedance, for example. 50 Ohms.

[0048] FIG. 5 illustrates input return loss (S 11 ) when the RF antenna port is matched to 50 Ohm or 'tuned' to the head model. The input return loss of the RF antenna port relates to the input impedance of that port.

[0049] FIG. 6 illustrates a table that summarizes the input return loss and input impedance measurements of the antenna of example embodimentswhen a transmission was conducted in the 2.4-2.5 GHz range for different cases. In one example, when a top plate of the RF antenna 350 was oriented towards the top of the SAM head, a best performance is measured in terms of return loss and input impedance.

[0050] In a 2.4-2.5 GHz range, a return loss (RL) from -9.5dB to -18dB was obtained. Lower values correspond to better matching. Other return losses where the RF antenna 350 was tuned to air, the top plate was not tuned to SAM, and where the bottom plate was tuned towards the top of the dummy SAM head produced higher, and thus less favorable, results.

[0051] One factor in tuning the combination antenna to the SAM model, and thus to a head of user of the apparatus, may correspond to the unbalanced manner in which the filament 335 may be formed along the outer shell of the RF antenna 350. Additionally the coil may be formed closer to either antenna plate 315 or 325 to allow a beneficial tuning to take place.

[0052] In the 2.4 GHz to 2.5 GHz range, input impedance was also measured. In this range the tuned antenna ranges from (62+j7) Ω to (57+j37) Ω. For the lesser favored orientations, input impedances were differing more from (50+j0) Ω.

[0053] FIG. 7 illustrates a block diagram including a radio integrated circuit connected to a combination antenna system of anembodiment such as in a hearing aid or similar devices. In the embodiment, the integrated circuit components illustrated in FIG. 7 maybe present in each hearingtype device situated in a hearing device on or near a user's body.

[0054] A hearing device 711 such as a hearing aid or ear bud may include hearing aid electronics 712 that include processing circuitry, a combination antenna apparatus 721 and a loud speaker and microphone unit 722. Hearing aid electronics 712 may receive and process audio received from the RF antenna and / or the MI antenna of the combination antenna apparatus 721, and may also transmit audio through the one or both of the RF antenna and MI antenna of the combination antenna 721.

[0055] Hearing aid electronics 712 may include radio circuitry 713 for RF communication and radio circuitry 714 for MI communication. An RF radio input / output interface 715 may connect to a RF feeding connection I / O port 719 of the combination antenna 721 through a connection 717 such as a connecting wire. An MI radio input / output interface 716 may connect to a magnetic antenna feeding I / O connection port 720 of the combination antenna 721 of embodiments described herein through a connection 718 such as a connection wire.

[0056] A combination antenna according to embodiments described herein may be formed in which near-field and far-field antenna communication systems may be combined in a single device, making use of beneficial characteristics of each antenna.

[0057] It should be noted that the above-mentioned embodiments illustrate rather than limit the embodiments described herein, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The embodiments described herein may be implemented by means of hardware including several distinct elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures maynot be used to advantage.

Claims

1. A pair of earpieces configured for antenna diversity, each earpiece comprising an antenna apparatus, each antenna comprising: a radio frequency, RF, antenna (350) for far-field communication, wherein the RF antenna comprises: an antenna body (340), the antenna body (340) being a three-dimensional support body; a first conductor plate (315) disposed at one end of the antenna body, the first conductor plate (315) being on a first surface of the antenna body; a second conductor plate (325) disposed at a second end of the antenna body, the second conductor plate (325) being on a second surface of the antenna body (340), wherein the first surface and the second surface are arranged on opposing ends of the antenna body (340); and an electrically conductive inductive wire (335) arranged within the antenna body of the RF antenna to electrically connect the first conductor plate (315) with the second conductor plate (325); a magnetic induction, MI, antenna (200) disposed within the RF antenna, the magnetic induction antenna comprising a magnetic coil structure for near-field communication; and each earpiece comprising electronic circuitry (712) configured to: (i) receive and process an audio transmission received from the RF antenna (350), and communicate the received and processed audio transmission via the MI antenna (200) to the MI antenna (200) of the other earpiece of the pair of earpieces; and (ii) receive and process an audio transmission received from the MI antenna (200) of the other earpiece of the pair of earpieces; the pair of earpieces configured such that, in operation, the earpiece currently receiving a clearer audio transmission is configured to communicate its received and processed audio transmission via its MI antenna (200) to the MI antenna (200) of the other earpiece of the pair of earpieces.

2. The pair of earpieces of claim 1, wherein the RF antenna and MI antenna (200) are cylindrical.

3. The pair of earpieces of claim 2, comprising a dielectric layer disposed between the MI antenna and the first conductor plate (315).

4. The pair of earpieces of claim 2 or claim 3, wherein the electrically conductive inductive wire (335) is arranged within the antenna body (340) in an unbalanced way.

5. The pair of earpieces of any of claims 1 to 4, comprising a first connection port (370) connected to the RF antenna (350) and a second connection port (210) connected to the MI antenna (200).

6. The pair of earpieces of any of claims 1 to 5, wherein the electronic circuitry transmits audio through the MI antenna (200) to a portion of a user's body.

7. The pair of earpieces of claim 1, wherein the antenna comprises a first (370) and a second (210) feeding connection, wherein the first (370) and second (210) feeding connections are configured to electrically connect to a signal processing device for processing an electrical signal received or to be transmitted by the antenna apparatus.

8. The pair of earpieces of claim 7, wherein a maximum dimension of the antenna apparatus is less than or equal to half a wavelength of a highest operating frequency of the antenna apparatus.

9. The pair of earpieces of claim 7 or 8, further comprising: a receiver or transmitter unit (712); and a matching unit connected between the receiver or transmitter unit and the antenna feeding connections (370) of the RF antenna (350), the matching unit being adapted to substantially match the impedance of the RF antenna (350) to the impedance of the receiver or transmitter unit.

10. A pair of hearing aids or a pair of ear buds, each hearing aid or ear bud corresponding to the pair of earpieces of any previous claim.