Wireless medical device with a complementary split ring resonator arrangement for suppression of electromagnetic interference
View Patent ↗A medical device as described herein includes a communication module to process radio frequency signals associated with operation of the medical device, an antenna associated with the communication module, and a microstrip transmission component coupled between the communication module and the antenna. The transmission component includes a dielectric substrate, an electrically conductive signal trace formed overlying the upper major surface of the substrate, an electrically conductive ground plane formed overlying the lower major surface of the substrate, and a complementary split ring resonator arrangement integrally formed in the ground plane, and having a layout and dimensions tuned to cause the resonator arrangement to resonate at one or more harmonic frequencies of the nominal transmission frequency of the radio frequency signals.
1. A medical device comprising:
a housing;
a radio frequency (RF) communication module to process RF signals associated with operation of the medical device, the RF signals having a nominal transmission frequency;
an RF antenna associated with the RF communication module, the RF antenna integrally formed with the housing;
a physically distinct microstrip transmission component coupled between the RF communication module and the RF antenna, the microstrip transmission component comprising:
a dielectric substrate having an upper major surface and a lower major surface opposite the upper major surface;
an electrically conductive signal trace formed overlying the upper major surface;
an electrically conductive ground plane formed overlying the lower major surface; and
a complementary split ring resonator (CSRR) arrangement integrally formed in the electrically conductive ground plane, and having a layout and dimensions tuned to cause the CSRR arrangement to resonate at a harmonic frequency of the nominal transmission frequency.
2. The medical device of claim 1 , wherein the CSRR arrangement comprises a plurality of CSRR elements in series and centered in alignment with the electrically conductive signal trace.
3. The medical device of claim 2 , wherein the CSRR elements are identical in layout and dimensions.
4. The medical device of claim 1 , wherein:
the RF communication module and the RF antenna accommodate RF signals having the nominal transmission frequency centered around 2.4 GHz; and
the layout and dimensions of the CSRR arrangement are tuned to cause the CSRR arrangement to resonate at a frequency centered around 4.8 GHz.
5. The medical device of claim 1 , wherein:
the electrically conductive signal trace is formed directly on the upper major surface; and
the electrically conductive ground plane is formed directly on the lower major surface.
6. The medical device of claim 1 , wherein:
the electrically conductive ground plane comprises a layer of electrically conductive material formed directly on the lower major surface; and
the CSRR arrangement is defined by voids formed in the electrically conductive material.
7. The medical device of claim 1 , wherein:
the electrically conductive ground plane comprises a layer of electrically conductive material formed directly on the lower major surface; and
the CSRR arrangement is defined by selective removal of portions of the electrically conductive material.
8. A medical fluid infusion device comprising:
a housing;
a radio frequency (RF) communication module to process RF signals associated with operation of the medical device, the RF signals having a nominal transmission frequency;
an RF antenna associated with the RF communication module, the RF antenna integrally formed with the housing;
a physically distinct microstrip transmission component coupled between the RF communication module and the RF antenna, the microstrip transmission component comprising:
a dielectric substrate having an upper major surface and a lower major surface opposite the upper major surface;
an electrically conductive signal trace formed overlying the upper major surface; and
an electrically conductive ground plane formed overlying the lower major surface; and
a complementary split ring resonator (CSRR) arrangement for the microstrip transmission component, the CSRR arrangement having a layout and dimensions tuned to cause the CSRR arrangement to suppress a harmonic frequency component of the nominal transmission frequency of the RF signals.
9. The medical fluid infusion device of claim 8 , wherein the CSRR arrangement comprises a plurality of CSRR elements in series and centered in alignment with the electrically conductive signal trace.
10. The medical fluid infusion device of claim 8 , wherein:
the electrically conductive signal trace is formed directly on the upper major surface; and
the electrically conductive ground plane is formed directly on the lower major surface.
11. The medical fluid infusion device of claim 8 , wherein the layout and dimensions of the CSRR arrangement are tuned to cause the CSRR arrangement to resonate at the harmonic frequency.
12. The medical fluid infusion device of claim 8 , wherein the CSRR arrangement is integrally formed in the electrically conductive ground plane.
13. The medical fluid infusion device of claim 12 , wherein:
the electrically conductive ground plane comprises a layer of electrically conductive material formed directly on the lower major surface; and
the CSRR arrangement is defined by voids formed in the electrically conductive material.
14. The medical fluid infusion device of claim 12 , wherein:
the electrically conductive ground plane comprises a layer of electrically conductive material formed directly on the lower major surface; and
the CSRR arrangement is defined by selective removal of portions of the electrically conductive material.
15. A medical device comprising:
a housing;
a radio frequency (RF) communication module to process RF signals associated with operation of the medical device, the RF signals having a nominal transmission frequency;
an RF antenna associated with the RF communication module, the RF antenna integrally formed with the housing;
a physically distinct microstrip transmission component coupled between the RF communication module and the RF antenna, the microstrip transmission component comprising:
a dielectric substrate having an upper major surface and a lower major surface opposite the upper major surface;
an electrically conductive signal trace formed on the upper major surface; and
a layer of electrically conductive material formed on the lower major surface, the layer of electrically conductive material comprising voids formed therein to define a complementary split ring resonator (CSRR) arrangement having a layout and dimensions tuned to cause the CSRR arrangement to resonate at a harmonic frequency of the nominal transmission frequency.
16. The medical device of claim 15 , wherein the layer of electrically conductive material serves as a ground plane for the electrically conductive signal trace.
17. The medical device of claim 15 , wherein the CSRR arrangement comprises a plurality of CSRR elements in series and centered in alignment with the electrically conductive signal trace.
18. The medical device of claim 17 , wherein the CSRR elements are identical in layout and dimensions.
19. The medical device of claim 17 , wherein each of the CSRR elements comprises:
an outer split ring shaped void formed in the electrically conductive material; and
an inner split ring shaped void formed in the electrically conductive material, the inner split ring shaped void residing in an interior space defined by the outer split ring shaped void, and the inner split ring shaped void being concentric with the outer split ring shaped void.
20. The medical device of claim 17 , wherein:
the outer split ring shaped void has a first line width;
the inner split ring shaped void has a second line width;
the outer split ring shaped void is separated from the inner split ring shaped void by a third line width; and
the first line width, the second line width, and the third line width are equal.