Wireless device antenna

Example antenna configured to be coupled to a first conductive structure having a first portion and a second portion, the antenna including: a second conductive structure having a first portion and a second portion; wherein the first portion of the second conductive structure is configured to be coupled to the first portion of the first conductive structure; a first feed point configured to be coupled to the second portion of the first conductive structure; wherein the first portion of the first conductive structure is configured to carry the RF signal current with a first current density; wherein the first portion of the second conductive structure is configured to carry the RF signal current with a second current density; wherein the first and second current densities are different.

The present specification relates to systems, methods, apparatuses, devices, articles of manufacture and instructions for wireless communication.

SUMMARY

According to an example embodiment, an antenna configured to be coupled to a first conductive structure having a first portion and a second portion, the antenna comprising: a second conductive structure having a first portion and a second portion; wherein the first portion of the second conductive structure is configured to be coupled to the first portion of the first conductive structure; a first feed point configured to be coupled to the second portion of the first conductive structure; wherein the second portion of the second conductive structure is coupled to a second feed point; wherein the first and second feed points are configured to be responsive to a radio frequency (RF) signal current; wherein the first portion of the second conductive structure is configured to be substantially in parallel with and have a different area than the first portion of the first conductive structure; wherein the first portion of the first conductive structure is configured to carry the RF signal current with a first current density; wherein the first portion of the second conductive structure is configured to carry the RF signal current with a second current density; and wherein the first and second current densities are different.

In another example embodiment, the second portion of the second conductive structure is configured to be substantially in parallel with and have a different area than the second portion of the first conductive structure; the second portion of the first conductive structure is configured to carry the RF signal current with a third current density; the second portion of the second conductive structure is configured to carry the RF signal current with a fourth current density; and the third and fourth current densities are different

In another example embodiment, the first and second spatial orientations are responsive to an RF far-field transverse wave; and the third and fourth spatial orientations are responsive to an RF surface wave.

In another example embodiment, the first portion of the second conductive structure is configured to be in galvanic contact with the first portion of the first conductive structure; the first feed point is configured to be in galvanic contact with the second portion of the first conductive structure; and the second portion of the second conductive structure is in galvanic contact with the second feed point.

In another example embodiment, the first conductive structure includes a power source having internal power circuitry.

In another example embodiment, the power source includes at least one of: a voltage source, a current source, or a wireless resonant coil.

In another example embodiment, the first conductive structure is a battery, the first portion of the first conductive structure is an anode, and the second portion of the first conductive structure is a cathode.

In another example embodiment, the first portion of the second conductive structure is configured to be galvanically coupled to the anode; and the second portion of the second conductive structure is galvanically coupled to an electronic circuit.

In another example embodiment, further comprising a ground-plane configured to be coupled between the first feed point and the second portion of the first conductive structure; wherein the ground-plane is configured to be substantially either parallel or perpendicular to the first portion of the first conductive structure.

In another example embodiment, the ground-plane, first and second feed points and second conductive structure are fixedly attached to a printed circuit board.

In another example embodiment, further comprising the first conductive structure; wherein the first conductive structure is a battery holding structure.

In another example embodiment, the first RF signal current spatial orientation has a first current density; the second RF signal current spatial orientation has a second current density; and the first and second current densities are different.

In another example embodiment, the first and second portions of the second conductive structure added to the coupling of the second feed point to the second portion of the second conductive structure is ¼ wavelength of a frequency of the RF signal.

In another example embodiment, a total electrical length of the first conductive structure, the second conductive structure, and the couplings to the first and second feed points is at least one tenth wavelength of a frequency of the RF signal.

In another example embodiment, a geometrical shape of the first portion of the second conductive structure is at least one of: a circular shape, a rectangular shape, or a spiral shape.

In another example embodiment, the antenna is embedded in at least one of: a dongle, a mobile device, a smartphone, a game console, a wireless device, a wearable device, a hearing aid, an earbud, a smart watch, an audio device, or a wireless road traffic device.

The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future Claim sets. The Figures and Detailed Description that follow also exemplify various example embodiments.

Various example embodiments may be more completely understood in consideration of the following Detailed Description in connection with the accompanying Drawings, in which:

DETAILED DESCRIPTION

Various wireless device form-factors, mobile or fixed, are getting smaller. For example, earbuds, hearing aids, wearable devices, and smartphones are shrinking in size and increasing in functional capability, such as communications between two sets of earbud pairs on different users. Upcoming V2X (Vehicle-to-Everything) and IoT (Internet of Things) devices are also planned for dramatic increase.

In some examples, wireless devices include earbuds or hearing aids. They can communicate by means of analogue or digital modulation techniques and can contain data or audio information. The audio can be high quality audio, like CD quality or can be of lower quality speech. In the former case a higher bandwidth of the communication channel is required.

Other wireless devices may include wearable devices, which in one example can be used in a car environment and designed to communicate various information (e.g. road traffic information) with other drivers, pedestrians, cars, bicycles, etc. according to various Car2X wireless communications standards.

Such wireless devices preferably are able to communicate using different wireless standards (e.g. Bluetooth, WIFI or Cellular), but also using different propagation modes. For example, a first propagation mode (i.e. off-body mode) can use transversal waves that propagate over long distances, and a second propagation mode (i.e. on-body mode) can use surface waves [(i.e. creeping wave, ground wave, traveling wave, etc.). Surface waves are part of a class of electromagnetic waves that diffract around surfaces, such as a sphere, a building, a person, and so on.

In some example embodiments, both the on-body and off-body modes use RF frequencies to communicate (e.g. ISM band communication may use a 2.4 GHz carrier frequency, and Car2X which uses a 5.9 GHz carrier frequency for road traffic and vehicle communication).

Adding such “on-body” and “off-body” communication to a wearable device is challenging due to the small form-factor of most wearable devices. For example an earbud can be as small as 15 mm, while the wavelength of a Bluetooth 2.5 GHz radio signal is 122 mm. Resonant antennas of a half wavelength (½λ) electrical length (i.e. 61 mm in this example) will work with good efficiency. However such a 61 mm antenna may not reasonably fit into an earbud with a length of 15 mm. The antenna's electrical length can also be influenced by dielectric materials or nearby objects or folding of the conductive structure.

FIG. 1Ais an example first wireless device antenna structure100. The antenna100consists of a transmission line with two conducting surfaces102,104, lines106,108,110, and a gap112. Either portion of the gap112becomes the feed points for the antenna100and are connected to another RF circuit (not shown). A non-conductive material114encases the antenna100. In one example, the first antenna structure100is integrated into a hearing aid.

The conducting surfaces102,104of the transmission line are opposite to each other and a distance between them can vary along their length. The length of conducting surfaces102,104of the transmission line, together with the position and length of line106determines a resonance frequency of the antenna100.

Lines106,108,110are the major radiating elements in this antenna100. This is because the currents in conducting surfaces102,104are opposite to each other, cancelling out their radiation. Currents in lines106,108,110are mainly going in the same direction and thereby generate far field radiation.

Conducting surfaces102,104do affect the electrical length of the antenna100and enable the antenna100to resonate at half a wavelength of the carrier frequency (61 mm at 2.5 GHz). As mentioned above, such a 61 mm electrical length in this design can be a serious burden in small hearing aids or earbuds.

FIG. 1Bis a first example circuit116corresponding to the first wireless device antenna structure100. Resistance (Rrad) in one example is much lower than 50 ohms and is transformed by an ideal transformer (TR). In resonance reactance XCa=reactance XLa.

FIG. 1Cis a second example circuit118corresponding to the first wireless device antenna structure200. In this example, Rrad is set to 50 ohms or lower and then matched externally. As before, in resonance reactance XCa=reactance XLa.

FIG. 2is a perspective view of an example second wireless device antenna structure200. The second wireless device antenna structure200is a loop antenna including a first conductive structure202(e.g. battery), a second conductive structure208(e.g. strip, clip, etc.), a ground-plane214, a dielectric area216, a printed circuit board (PCB)218, a first feed point220, a second feed point222, a conductor224(e.g. wire trace on PCB), an RF circuit226(e.g. radio integrated circuit (RF-IC)), and a holding structure228(e.g. battery holder). This loop antenna200can be designed for series mode resonance as will be discussed.

The first conductive structure202(e.g. battery) includes a first portion204(e.g. top of the battery) substantially parallel to the ground-plane214, a second portion206(e.g. side of the battery) substantially perpendicular to the ground-plane214. A geometrical shape of the first portion210of the second conductive structure208can be: circular, rectangular, spiral, or any other shape.

The second conductive structure208(e.g. strip, clip, etc.) includes a first portion210(e.g. over top of battery) and a second portion212(e.g. next to side of battery).

The antenna200is configured to be coupled to the first conductive structure202(e.g. battery) however, the first conductive structure202in some embodiments is a removeable battery or power source. The first portion210of the second conductive structure208is configured to be coupled to the first portion204of the first conductive structure202. The first feed point220is configured to be coupled to the second portion206of the first conductive structure202. The second portion212of the second conductive structure208is coupled to the second feed point222. In some example embodiments conductor224(e.g. wire trace on PCB) connects the second portion212of the second conductive structure208to the second feed point222.

The first and second feed points220,222are configured to be responsive to (e.g. transmit or receive) an RF signal current to and/or from the RF circuit226.

The first portion210of the second conductive structure208is configured to be substantially in parallel with and have a different area than the first portion204of the first conductive structure202. Due to this difference in area the first portion204of the first conductive structure202will carry the RF signal current with a first current density, and the first portion210of the second conductive structure208will carry the RF signal current with a second current density. These first and second current densities are different. In some example embodiments, these differences between the first and second current densities enable the antenna200to be responsive to a far-field RF transverse wave with a polarization in the direction of the first portion210(discussed further below).

The second portion212of the second conductive structure208is configured to be substantially in parallel with and have a different area than the second portion206of the first conductive structure202. Thus, the second portion206of the first conductive structure202carries the RF signal current with a third current density, and the second portion212of the second conductive structure208carries the RF signal current with a fourth current density. These third and fourth current densities are different. In some example embodiments, these differences between the third and fourth current densities enable the antenna200to be responsive to an RF surface wave (also discussed further below).

The RF currents are spread out across the various portion204,206,210,212surfaces, which have different spatial orientations. Since these RF currents go in different directions and the portions204,206,210,212have different areas, far field radiation in multiple polarizations suitable for different communication modes is enabled.

In some example embodiments, the first portion210of the second conductive structure208is configured to be in galvanic contact with the first portion204of the first conductive structure202; the first feed point220is configured to be in galvanic contact with the second portion206of the first conductive structure202; and the second portion212of the second conductive structure208is in galvanic contact with the second feed point222.

In certain example embodiments, the first conductive structure202includes a power source having internal power circuitry. The power source may include either: a voltage source, a current source, or a wireless charging resonant coil.

In other example embodiments, the first conductive structure202is a battery, the first portion204of the first conductive structure202is an anode, and the second portion206of the first conductive structure202is a cathode. In example embodiments with galvanic coupling, the first portion210of the second conductive structure208is galvanically coupled to the anode; and the second portion212of the second conductive structure208is galvanically coupled to an electronic circuit (not shown) that provides supporting circuitry for the antenna200and/or other electronic functions.

While not all example embodiments require the ground-plane214, those that do can couple the ground-plane214between the first feed point220and the second portion206of first conductive structure202(e.g. battery). While as introduced above, the ground-plane214can be substantially parallel to the first portion204of the first conductive structure202, in an alternate embodiment the ground-plane214can be substantially perpendicular to the first portion204of the first conductive structure202. In some examples, the ground-plane214made from copper, perhaps a 35 micrometer thin copper layer.

In some example embodiments, the ground-plane214, first and second feed points and second conductive structure208are fixedly attached to the printed circuit board218. The printed circuit board218can be a flexible material or any other substrate that can contain electronic components and conductors. A second printed circuit board (PCB) can be positioned, perhaps on top of the first conductive structure202(e.g. battery), to add additional circuitry. These printed circuit boards can include various other electronic components such as communication IC's. SeeFIG. 4for additional circuits that can be included.

Some example embodiments, may further include a battery holding structure228.

The antenna200may be further tuned for various resonant frequencies by adjusting a ratio of an area of the ground-plane214to the dielectric area216on the PCB218. A length of conductor224near or printed on the PCB218within the dielectric area216can also be adjusted to tune the antenna200. The dielectric area216also isolates the first and second feed points220,222.

In some example embodiments, a total electrical length of the first conductive structure202, the second conductive structure208, and the couplings to the first and second feed points220,222is at least one tenth (i.e. 0.1) wavelength of a frequency of the RF signal to ensure a minimal wireless communications performance. Additional tuning of the electrical length can be done using matching.

In various example embodiments, the antenna200is embedded in perhaps: a dongle, a mobile device, a smartphone, a game console, a wireless device, a wearable device, a hearing aid, an earbud, a smart watch, an audio device, or a wireless road traffic device.

During operation of some examples of the antenna200, particularly those whose first conductive structure202is a battery, at DC (i.e. 0 Hz) the antenna structure200is shorted. Then at a first resonance frequency (F1) the antenna structure200has a high impedance between the feed points220,222and may be difficult to impedance match to a further electronic circuit. Further at a second resonance frequency (F2) the antenna structure200has a low impedance between the feed points220,222and can easily be impedance matched to a further electronic circuit.

FIG. 3is a top view of the example second wireless device antenna structure200.

FIG. 4is an example circuit400coupled to the example second wireless device antenna structure200. The antenna200feed points220,222are coupled to a set of electronics402. The set of electronics402include a tuning unit404, a balun406, and electronics408(e.g. radio and other wireless device functional circuits).

The tuning unit404impedance matches the antenna200to an impedance of the balun406. At the RF antenna200operational frequencies, the balun406matches a balanced interface from the electronics408with an unbalanced interface from the tuning unit404. Depending on the electronics408, the balun406may or may not be optional.

Impedance matching maximizes power transfer between the electronics408and the antenna200in both transmit and receive modes.

FIG. 5is a side view of an example first earbud500including the example second wireless device antenna structure200. In this example500the earbud includes a loudspeaker502to reproduce audio signals. Radio and other electronics (not shown) are also included for earbud500functionality.

As shown inFIG. 5, the first portion210of the second conductive structure208and the first portion204of the first conductive structure202are configured to be responsive to (e.g. radiate and/or receive) a transverse RF wave. In one example embodiment, the first portion210is a metal clip over top of a battery anode (i.e. the first portion204), and when the earbud500is inserted into a person's ear, the two first portions204and210will be parallel to the person's skin and be responsive to transverse RF wave.

Also as shown inFIG. 5, the second portion212of the second conductive structure208and the second portion206of the first conductive structure202are configured to radiate a surface RF wave. In one example embodiment, the second portion212is a continuation of the metal clip passing over the side of the battery (i.e. the second portion206), and when the earbud500is inserted into a person's ear, the two second portions206and212will be perpendicular (i.e. normal) to the person's skin and be responsive to surface RF signals.

In this example embodiment, the antenna structure200is indistinguishable from the normal battery202connections and takes no appreciable space inside the earbud500. Similar indistinguishable installations are possible for other wireless devices.

FIG. 6is an example600of how the first earbud500and a second earbud602including the example second wireless device antenna structure200can function as a wearable on a user606.

In one example, the antenna structure200in the earbuds500,602is positioned according an imaginary line XX604. This allows the antennal structure200to generate an electric field that is normal (i.e. perpendicular) to the skin of the user606. Two modes of propagation, discussed earlier, are generated.

The first mode is an “on-body” mode where an electrical field vector is normal (i.e. perpendicular) to the user's606skin, for transmission and reception of the surface RF wave discussed inFIG. 5. With the “on-body” mode, “direct” communication from ear to ear is possible.

The second mode is the “off-body” mode where the electrical field vector is substantially parallel with the user's606skin, and where RF far-field transversal waves, discussed inFIG. 5, are generated and received. In the “off-body” mode, distant communication with another device (i.e. a smartphone, another earbud, a Car2X device, etc.) positioned away from the user606is possible.