A Triple Band Circularly Polarized Antenna for Leadless Cardiac Transcatheter Pacing System

Abstract

The ground-breaking entry of leadless cardiac pacemakers in the cardiac pacemaker’s world has resulted in the design of ultracompact implantable antennas. In this article, we developed a circularly polarized fractal-shaped open-loop antenna for leadless cardiac transcatheter pacing (TCP) system operating at industrial, scientific, and medical bands (915 MHz, 2.4 GHz, and 5.8 GHz). The proposed antenna was constructed on the high permittivity dielectric material Rogers RT/Duroid 6010 LM ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r} = 10$ </tex-math></inline-formula> ) with a tiny footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 3\times0.254$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . To the best of our knowledge, this is the smallest footprint antenna that works in triple bands with circular polarization, compared with the other reported implantable antennas. We placed the antenna inside the TCP system to evaluate its performance in a realistic environment. Subsequently, it is placed deep inside at the center of the multilayer (skin–fat–muscle) phantom model with dielectric properties equivalent to the human heart. Furthermore, the antenna was integrated into a 3-D printed TCP capsule with dummy electronics for experimental verification, and its performance was checked in the ballistic gel phantom and minced pork. The measured impedance bandwidths of the antenna at 915 MHz, 2.4 GHz, and 5.8 GHz are 580 MHz, 900 MHz, and 1.2 GHz, respectively. Correspondingly, the measured axial ratio bandwidths in phantom are 255 MHz, 260 MHz, and 370 MHz, and measured gain values are −35.1 dBi, −31.6 dBi, and −26.7 dBi.