Loaded RF antenna for implantable device

1. A system comprising:

an implantable telemetry circuit;

an implantable antenna electrically connected to the implantable telemetry circuit, the implantable antenna comprising:

a first non-coil segment having a proximal end and a distal end, wherein the proximal end is connected to the implantable telemetry circuit; and

a first coil having a proximal end and a distal end, wherein the proximal end is attached to the distal end of the first non-coil segment, and wherein the first coil comprises a continuous series of contiguous turns disposed about a first longitudinal axis; and

a second non-coil segment attached to the distal end of the first coil; and

wherein the implantable antenna is configured to wirelessly transfer information electromagnetically using a first specified operating frequency range and a second specified operating frequency range, wherein the first specified frequency range is established by a first resonant frequency and the different second specified operating frequency is established by a different second resonant frequency, and wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the first coil with respect to the first non-coil segment and the second non-coil segment;

an implantable housing sized and shaped for implant within a human or animal body, the implantable housing comprising a conductive material and containing at least a portion of the implantable telemetry circuit, wherein the conductive material is electrically connected to the implantable telemetry circuit;

a first implantable dielectric compartment sized and shaped for implant within a human or animal body, the first implantable dielectric compartment containing at least a portion of the first non-coil segment of the implantable antenna, and wherein the first implantable dielectric compartment is coupled to the housing; and

a second implantable dielectric compartment sized and shaped for implant within a human or animal body, the second implantable dielectric compartment containing the first coil of the implantable antenna, wherein the second implantable dielectric compartment is coupled to the housing, and wherein the first coil is configured to follow an exterior contour of the implantable housing.

2. The system of claim 1 , wherein a first mid-band frequency, centered in the first specified operating frequency range, is offset from a second mid-band frequency, centered in the second operating frequency range, by at least an octave.

3. The system of claim 2 , wherein the first and second specified operating frequency ranges are selected from a list including at least one of:

(1) a Medical Implant Communications Service (MICS) band range extending from approximately 402 MHz. to approximately 405 MHz.;

(2) a Short Range Device (SRD) band range extending from approximately 862 MHz. to approximately 870 MHz.;

(3) a first Industrial-Scientific-Medical (ISM) band range extending from approximately 902 MHz. to approximately 928 MHz.; or

(4) a second ISM band range extending from approximately 2400 MHz. to approximately 2500 MHz.

4. The system of claim 1 , wherein an entire length of the implantable antenna is less than or equal to a quarter of a longest specified operating wavelength of the implantable antenna in a biological medium.

5. The system of claim 1 , wherein the physical arrangement of the first coil with respect to the first non-coil segment is configured to provide an input impedance approximating a conjugate match to an output impedance of the implantable telemetry circuit for at least one of the first and second operating frequency ranges when the implantable antenna is implanted in a biological medium.

6. The system of claim 5 , wherein the first coil is configured to inductively load the implantable telemetry circuit.

7. The system of claim 1 , comprising:

an external telemetry module comprising:

an external antenna; and

an external telemetry circuit electrically connected to the external antenna;

wherein the implantable antenna and the external antenna are wirelessly coupled; and

wherein the external antenna is configured to wirelessly transfer information electromagnetically between the implantable medical assembly and the external telemetry module using at least one of the first or second specified operating frequency ranges.

8. The system of claim 1 , wherein the implantable antenna comprises a biocompatible conductive material.

9. The system of claim 8 , wherein at least a portion of the implantable antenna is configured to be exposed to tissue when the implantable antenna is implanted in a biological medium.

10. A method, comprising:

providing an implantable housing sized and shaped for implant within a human or animal body, the implantable housing comprising a conductive material and containing at least a portion of an implantable telemetry circuit, wherein the conductive material is electrically connected to the implantable telemetry circuit;

providing a first implantable dielectric compartment sized and shaped for implant within a human or animal body, wherein the first implantable dielectric compartment is coupled to the housing;

providing a second implantable dielectric compartment sized and shaped for implant within a human or animal body, wherein the second implantable dielectric compartment is coupled to the housing;

wirelessly transferring information electromagnetically at a first specified operating frequency range and at a second specified operating frequency range using an implantable antenna, the implantable antenna comprising:

a first non-coil segment having a proximal end and a distal end, wherein the proximal end is connected to the implantable telemetry circuit; and

a first coil having a proximal end and a distal end, wherein the proximal end is attached to the distal end of the first non-coil segment, wherein the first coil comprises a continuous series of contiguous turns disposed about a first longitudinal axis; and

a second non-coil segment attached to the distal end of the first coil; and

wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the first coil with respect to the first non-coil segment and the second non-coil segment;

wherein the first specified operating frequency range is established by a first resonant frequency and the second specified operating frequency is established by a different second resonant frequency,

wherein the first implantable dielectric compartment contains at least a portion of the first non-coil segment of the implantable antenna, and

wherein the second implantable dielectric compartment contains the first coil of the implantable antenna, and wherein the first coil is configured to follow an exterior contour of the implantable housing.

11. The method of claim 10 , wherein the wirelessly transferring information electromagnetically includes using the first specified operating frequency range having a first mid-band frequency and the second specified operating frequency range having a second mid-band frequency, and wherein the first mid-band frequency is offset from the second mid-band frequency by at least an octave.

12. The method of claim 10 , comprising substantially matching a conjugate impedance of the implantable antenna in a biological medium using the implantable telemetry circuit.

13. The method of claim 12 , wherein the substantially matching includes inductively loading the implantable telemetry circuit using the first coil.

14. The method of claim 10 , comprising:

driving the implantable antenna using the implantable telemetry circuit; and

wherein the wirelessly transferring information electromagnetically includes wirelessly transferring information electromagnetically between the implantable antenna and an external telemetry module antenna using at least one of the first specified operating frequency range or the second specified operating frequency range.

15. The method of claim 10 , wherein the implantable antenna comprises a biocompatible conductive material.

16. The method of claim 15 , wherein at least a portion of the implantable antenna is configured to be exposed to tissue when the implantable antenna is implanted in a biological medium.