# US 2021/0083370 A1 · Capacitively loaded implantable loop antenna > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0083370 A1 - Document ID: US20210083370A1 - Status: Published application - Kind: A1 - Application number: 17/016,125 - Filed: 2020-09-09 - Published: 2021-03-18 - Earliest claimed: 2019-09-13 - Assignees: Cardiac Pacemakers, Inc. - Applicants: Cardiac Pacemakers, Inc. - Inventors: Daniel Joseph Landherr; Niharika Varanasi; John E. Hansen; Keith R. Maile; Benjamin J. Haasl; Jason Lahr - Web page: https://patentgrep.com/patent/US20210083370A1 ## CPC - H01Q 1/273: {Adaptation for carrying or wearing by persons or animals} - A61N 1/37229: {Shape or location of the implanted or external antenna} - A61N 1/3752: {Details of casing-lead connections} - H01Q 1/48: Earthing means; Earth screens; Counterpoises - H01Q 7/00: Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop - H04Q 9/00: Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom - H04Q 2209/43: using wireless personal area networks [WPAN], e.g. 802.15, 802.15.1, 802.15.4, Bluetooth® or Zigbee® - H04Q 2213/003: Constructional details - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract A capacitively loaded loop antenna for an implantable medical device is disclosed comprising a feed extending from a conductive surface of an implantable housing, a radiating element having a cross section larger than the feed, and a return coupling the radiating element to a conductive surface of the implantable housing. The radiating element can have a height above the top surface of the implantable housing, creating a capacitance between the radiating element and the conductive surface of the implantable housing configured to counteract the inductance of the capacitively loaded loop antenna. ## Claims ### Claim 1 An implantable medical device, comprising: an implantable housing comprising a conductive surface; a header coupled to an outer surface of the implantable housing; control circuitry within the implantable housing, the control circuitry, including a telemetry circuit configured to enable radio frequency communication with an external device separate from the implantable medical device; and a capacitively loaded loop antenna disposed within the header and coupled to the telemetry circuit, the capacitively loaded loop antenna configured to facilitate radio frequency communication comprising a feed, a radiating element, and a return to the conductive surface of the implantable housing, creating an inductance between the feed and the conductive surface, wherein the feed extends normal to the conductive surface of the implantable housing, coupling the telemetry circuit to the radiating element through a connector block, wherein the radiating element comprises a conductor having a larger cross section than the feed and the return, and a height above the top surface of the implantable housing, creating a capacitance between the radiating element and the conductive surface, wherein the capacitance of the radiating element is configured to counteract the inductance of the capacitively loaded loop antenna, and wherein the return extends normal to the conductive surface of the implantable housing, coupling the radiating element to the conductive surface of the implantable housing, wherein the conductive surface of the implantable housing functions as a ground plane for the capacitively loaded loop antenna. ### Claim 2 (depends on 1) The implantable medical device of claim 1, wherein the telemetry circuit and the capacitively loaded loop antenna are configured to communicate at a desired communication frequency between 2.4 and 2.48 GHz when implanted in the body. ### Claim 3 (depends on 1) The implantable medical device of claim 1, wherein the capacitively loaded loop antenna has a radiation resistance between 25 and 100 ohms. ### Claim 4 (depends on 3) The implantable medical device of claim 3, wherein the capacitively loaded loop antenna is a 50-ohm antenna. ### Claim 5 (depends on 1) The implantable medical device of claim 1, wherein the capacitance of the radiating element is configured to cancel the inductance of the capacitively loaded loop antenna. ### Claim 6 (depends on 1) The implantable medical device of claim 1, wherein the distance between the feed and the return is selected to provide a radiation resistance of the capacitively loaded loop antenna between 25 and 100 ohms. ### Claim 7 (depends on 1) The implantable medical device of claim 1, wherein the radiating element has a resonating frequency in the header between 2.4 and 2.48 GHz when implanted in the body. ### Claim 8 (depends on 1) The implantable medical device of claim 1, wherein the radiating element comprises a planar conductor having a length and width along a top surface of the implantable housing and a thickness normal to the top surface of the implantable housing. ### Claim 9 (depends on 8) The implantable medical device of claim 8, wherein the length, width, and thickness of the radiating element in the header is selected to resonate at a communication frequency between 2.4 and 2.48 GHz when implanted in the body. ### Claim 10 (depends on 9) The implantable medical device of claim 9, wherein the length of the radiating element is between 5 and 8 mm, the width of the radiating element is between 1 and 2.5 mm, and the thickness of the radiating element is between 0.2 and 0.6 mm. ### Claim 11 (depends on 10) The implantable medical device of claim 10, wherein the height of the radiating element above the top surface of the implantable housing is between 7 and 11 mm. ### Claim 12 (depends on 1) The implantable medical device of claim 1, wherein the radiating element has a length along the top surface of the implantable housing, wherein the height of the radiating element above the top surface of the implantable housing is greater than the length of the radiating element. ### Claim 13 (depends on 1) The implantable medical device of claim 1, wherein the radiating element has a length and width along the top surface of the implantable housing, wherein the length of the radiating element is greater than the width, and wherein the height of the radiating element above the top surface of the implantable housing is greater than the length of the radiating element. ### Claim 14 (depends on 1) The implantable medical device of claim 1, wherein the radiating element is parallel to the top surface of the implantable housing. ### Claim 15 (depends on 1) The implantable medical device of claim 1, wherein the header is composed of a material having a dielectric constant between 2 and 5, and wherein the header is configured to electrically isolate the capacitively loaded loop antenna from tissue of a patient when implanted. ### Claim 16 An implantable medical device, comprising: an implantable housing comprising a conductive surface; a header coupled to an outer surface of the implantable housing; control circuitry within the implantable housing, the control circuitry, including a telemetry circuit configured to enable radio frequency communication with an external device separate from the implantable medical device; and a capacitively loaded loop antenna disposed within the header and coupled to the telemetry circuit, the capacitively loaded loop antenna configured to facilitate communication at a communication frequency between 2.4 and 2.48 GHz when implanted in the body, the capacitively loaded loop antenna comprising a feed, a radiating element, and a return to the conductive surface of the implantable housing, creating an inductance between the feed and the conductive surface, wherein the feed extends normal to the conductive surface of the implantable housing, coupling the telemetry circuit to the radiating element through a connector block, wherein the radiating element comprises a planar conductor having a length and width parallel to a portion of a top surface of the implantable housing, a thickness normal to the top surface of the implantable housing, and a height above the top surface of the implantable housing, creating a capacitance between the radiating element and the conductive surface, wherein the capacitance of the radiating element is configured to counteract the inductance of the capacitively loaded loop antenna, and wherein the return extends normal to the conductive surface of the implantable housing, coupling the radiating element to the conductive surface of the implantable housing, wherein the conductive surface of the implantable housing functions as a ground plane for the capacitively loaded loop antenna. ### Claim 17 (depends on 16) The implantable medical device of claim 16, wherein the radiating element has a resonating frequency in the header between 2.4 and 2.48 GHz when implanted in the body, and wherein the header is composed of a material having a dielectric constant between 2 and 5. ### Claim 18 (depends on 16) The implantable medical device of claim 16, wherein the length of the radiating element is between 5 and 8 mm, the width of the radiating element is between 1 and 2.5 mm, the thickness of the radiating element is between 0.2 and 0.6 mm, and the height of the radiating element above the top surface of the implantable housing is between 7 and 11 min, and wherein the capacitively loaded loop antenna has a radiation resistance between 25 and 100 ohms. ### Claim 19 (depends on 18) The implantable medical device of claim 18, wherein the length of the radiating element is 7.1 mm, the width of the radiating element is 1.5 mm, the thickness of the radiating element is 0.4 mm, and the height of the radiating element above the top surface of the implantable housing is 8.3 mm. ### Claim 20 (depends on 19) The implantable medical device of claim 19, wherein the length of the radiating element is 5.7 mm, the width of the radiating element is 1.75 mm, the thickness of the radiating element is 0.4 mm, and the height of the radiating element above the top surface of the implantable housing is 9.6 mm.