Conformal antenna for an implantable medical device
An implantable medical device (IMD) configured for implant in a body includes an enclosure that houses communication circuitry, an antenna, a dielectric layer, and a transmission line. The enclosure includes an outer surface configured to be oriented in a direction facing the exterior of the body and to be placed adjacent tissue. The antenna includes a ground plane corresponding to the enclosure, a dielectric spacer that conforms to the outer surface of the enclosure, and a radiating element that conforms to the dielectric spacer. The dielectric layer overlays the radiating element and the dielectric spacer. The transmission line is electrically connected between the radiating element and the communication circuitry.
1 . An implantable medical device (IMD) configured for implant in a body, the IMD comprising:
an enclosure that houses communication circuitry, and comprising an outer surface configured to be oriented in a direction facing the exterior of the body and to be placed adjacent tissue;
an antenna including:
a ground plane corresponding to the enclosure;
a dielectric spacer that conforms to the outer surface of the enclosure; and
a radiating element that conforms to the dielectric spacer;
a dielectric layer that overlays the radiating element and the dielectric spacer;
a transmission line outside the enclosure and electrically coupled between the radiating element and the communication circuitry; and
a rectangular structure that is co-planar with and spaced apart from the radiating element, conformed to a portion of the dielectric spacer, and electrically coupled to the ground plane through a feedthrough,
wherein the transmission line extends from the radiating element to a region adjacent to and spaced apart from the rectangular structure and the rectangular structure has a slot that exposes a portion of the dielectric spacer, and the transmission line is spaced apart from the rectangular structure and extends into and along a length of the slot.
2 . The IMD of claim 1 , wherein the ground plane corresponding to the enclosure is non-planar.
3 . The IMD of claim 1 , wherein the radiating element is non-planar.
4 . The IMD of claim 1 , wherein the outer surface of the enclosure that supports the dielectric spacer is characterized by a non-linear profile having a first curvature and the radiating element is characterized by a non-linear profile having a second curvature that generally corresponds to the first curvature.
5 . The IMD of claim 1 , wherein the radiating element is characterized by a notched, rectangular shape.
6 . The IMD of claim 1 , wherein the radiating element is formed of a conductive material and has a thickness in a range of a 4 mils to 30 mils (~0.1 mm up to 0.8 mm).
7 . The IMD of claim 1 , wherein the enclosure is formed of a conductive material and the portion of the enclosure beneath the dielectric spacer has a thickness in a range of a 4 mils to 30 mils (~0.1 mm up to 0.8 mm).
8 . The IMD of claim 1 , wherein the dielectric spacer has a dielectric constant at a specific radio frequency that is a fraction the dielectric constant of tissue at the specific radio frequency.
9 . The IMD of claim 8 , wherein the dielectric constant of the dielectric spacer is in a range of 2 to 5.
10 . The IMD of claim 1 , wherein the dielectric spacer is formed of a biocompatible plastic and has a thickness in a range of a 4 mils to 30 mils (~0.1 mm up to 0.8 mm).
11 . The IMD of claim 1 , wherein the dielectric layer is formed of a biocompatible material and has a thickness in a range of a 4 mils to 30 mils (~0.1 mm up to 0.8 mm).
12 . The IMD of claim 1 , wherein the antenna operates in a frequency band in a range of at least one of 2.4 GHz to 2.5 GHz and from 5.15 GHz to 5.85 GHz.
13 . The IMD of claim 1 , wherein the antenna has a peak radiation gain in a range of −10 dB to −13 dB when implanted under skin.
14 . The IMD of claim 13 , wherein the antenna operates in a first frequency band in a range of 2.4 GHz to 2.5 GHZ, and in a second frequency band in a range of 5.15 GHZ to 5.85 GHz.
15 . The IMD of claim 1 , further comprising second communication circuitry and a second transmission line, wherein the second transmission line is electrically coupled between the radiating element and the second communication circuitry.
16 . The IMD of claim 1 , further comprising at least one antenna feedthrough electrically coupled to the communication circuitry, and that extends through the enclosure at a location remote from the radiating element, wherein the transmission line is electrically coupled to the communication circuitry through the at least one antenna feedthrough.
17 . The IMD of claim 1 , wherein the dielectric spacer, the transmission line, and the dielectric layer extend together along the outer surface of the enclosure to a location remote from the radiating element.