Near-field wireless device including a first near-field antenna and a second near-field antenna

1. A near-field wireless device, comprising:

a stack of three layers distributed along a first axis;

a first near-field antenna having a conductive surface and embedded in a first layer within the stack of layers;

wherein the conductive surface is configured to carry non-propagating quasi-static near-field electric-induction signals for on-body near-field communications;

wherein the first near-field antenna further includes an inductive loop configured to carry non-propagating quasi-static near-field magnetic-induction signals for on-body near-field communications;

a second near-field antenna having an inductive loop and embedded in a second layer within the stack of layers;

wherein the inductive loop of the second near-field antenna is configured to carry non-propagating quasi-static near-field magnetic-induction signals for off-body near-field communications;

wherein the first and second layers are different layers; and

wherein the first and second antennas are not in galvanic contact;

further comprising a substrate embedded in a third layer within the stack of layers;

wherein the conductive surface of the first near-field antenna is on one side of the substrate; and

wherein the inductive loop of the second near-field antenna is on a side opposite to the one side of the substrate; and

wherein the substrate is configured to attenuate the near-field magnetic-induction signals generated by the second near-field antenna during off-body communications from interfering with near-field magnetic-induction signals received by the first near-field antenna during on-body communications.

2. The device of claim 1 :

wherein the conductive surface forms a first planar surface; and

wherein the inductive loop forms a second planar surface.

3. The device of claim 1 :

wherein the substrate has a permeability larger than ambient air.

4. The device of claim 1 :

wherein the first near-field antenna and the second near-field antenna are both NFEMI (near-field electromagnetic induction) antennas.

5. The device of claim 1 :

wherein the device is configured to position the conductive surface of the first near-field antenna closer to a user's body than the inductive loop of the second near-field antenna.

6. The device of claim 1 :

further comprising a cavity passing through each of the stack of layers distributed along the first axis; and

wherein the cavity is configured to be coupled to a sensor configured to measure an on-body user attribute.

7. The device of claim 6 :

wherein the sensor is a glucose sensor.

8. The device of claim 1 :

wherein the on-body near-field communications are hosted by a user's body including at least one of: a human body, a vehicle body, a robot, a docking device, a physical coupling system, or a tool or storage station on an assembly line.

9. The device of claim 1 :

wherein the device is embedded in at least one of: a wearable, a glucose monitor, a medical device, a smart watch, an earbud, a hearing aid, a headphone, an activity tracker, or a heart rate monitor.

10. The device of claim 1 :

further comprising a controller and a power source internal to the wireless device;

wherein controller is configured to self-initiate communications between the device and a second wireless device using the first near-field antenna and the power source; and

wherein controller is configured to receive power and respond to communications from a third wireless device using the second near-field antenna.

11. The device of claim 10 :

wherein the second near-field antenna is an NFC antenna.

12. The device of claim 10 :

wherein controller is configured to charge the power source using the received power from the third wireless device.

13. The device of claim 1 :

further comprising a controller;

wherein controller is configured to prevent signal transmission from the first near-field antenna and the second near-field antenna at a same time.

14. The device of claim 1 :

further comprising a controller;

wherein the first near-field antenna includes a first set of feed points configured to be coupled to a first tuning circuit;

wherein the second near-field antenna includes a second set of feed points configured to be coupled to a second tuning circuit; and

wherein the controller electrically separates the first tuning circuit from the second tuning circuit.

15. The device of claim 14 :

wherein the tuning circuits include a set of capacitive and resistive tuning parameters;

wherein the capacitive tuning parameters are configured to separately adjust a resonance frequency for the first and second antennas; and

wherein the resistive tuning parameters are configured to separately adjust an operational bandwidth of the first and second antennas.

16. A near-field wireless device, comprising:

a stack of three layers distributed along a first axis;

a first near-field antenna having a conductive surface and embedded in a first layer within the stack of layers;

wherein the conductive surface is configured to carry non-propagating quasi-static near-field electric-induction signals for on-body near-field communications;

wherein the first near-field antenna further includes an inductive loop configured to carry non-propagating quasi-static near-field magnetic-induction signals for on-body near-field communications;

a second near-field antenna having an inductive loop and embedded in a second layer within the stack of layers;

wherein the inductive loop of the second near-field antenna is configured to carry non-propagating quasi-static near-field magnetic-induction signals for off-body near-field communications;

wherein the first and second layers are different layers; and

wherein the first and second antennas are not in galvanic contact;

further comprising a substrate embedded in a third layer within the stack of layers;

wherein the conductive surface of the first near-field antenna is on one side of the substrate; and

wherein the inductive loop of the second near-field antenna is on a side opposite to the one side of the substrate;

further comprising a set of supporting circuits also on the side opposite to the one side of the substrate; and

wherein the substrate is configured to attenuate magnetic fields generated by the supporting circuits from interfering with near-field magnetic-induction signals received by the first near-field antenna during on-body communications.