Circularly Polarized Miniaturized Implantable Antenna for Leadless Pacemaker Devices
Abdenasser Lamkaddem, Ahmed El Yousfi, Kerlos Atia Abdalmalak, Vicente González Posadas, Daniel Segovia-Vargas
Abstract
A compact circularly polarized (CP) implantable antenna working at 915 MHz, at the industrial, scientific, and medical (ISM) band, is developed in this article. The proposed radiator is based on a fully planar and low-profile patch antenna with a ground plane and different slots but without any via holes, which makes the structure a good candidate for implantable devices. The circular polarization is achieved by means of introducing a surrounding and asymmetrical U-shaped structure. A meander line has been included in the inside of the U-shaped structure to increase the electrical length of the antenna without increasing its mechanical dimensions. An impedance bandwidth of 18.9% from 810 to 980 MHz and an axial ratio of 17.2% from 850 to 1010 MHz have been achieved. The proposed antenna has a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.2\times 5.6\times0.25$ </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> , which seems to be the smallest antenna over the recently reported implantable antennas. In addition, the proposed antenna achieves a relatively high gain value of −23 dBi.