3D printed circularly polarized implantable antenna with wideband impedance matching

This article proposes a slot-loaded circularly polarized implantable antenna with wide bandwidth at 2.45 GHz, i.e., Industrial, Scientific, and Medical (ISM) band. This antenna is established with a compact size of 44.52 mm3 based on 3D printing technology, and biocompatible material MED610 is adopted for human safety consideration. During the design, unilaterally shorted patch antenna loaded with T-slot is adopted, obtaining two closely spaced orthogonal modes with miniaturized antenna size. More importantly, to obtain wide impedance matching, a spiral slot is introduced around the feed, forming an L-section network consisted of a parallel capacitor and a series inductor. As a result, a wide circular polarization bandwidth of 28.7 % is realized for the proposed antenna. The measured results are well agreed with simulated results.