A compact circularly polarized antenna for in-body wireless communications

A compact single-fed circularly polarized (CP) patch antenna, operating at Industrial, Scientific, and Medical (ISM) band of 2.42–2.48 GHz, is investigated for implantable telemetry applications. Slow-wave effect is introduced by embedding reactive triangle patches to the proposed antenna, thus obtaining a compact size of 9.6 × 9.6 × 1.27 mm 3 . The slits are adopted and their sizes are adjusted asymmetrically, generating circular polarization. The simulated results show that bandwidths of the 10-dB return loss and 3-dB axial-ratio are around 12% (2.26– 2.55 GHz) and 3.2% (2.41–2.49 GHz) at ISM band, respectively. Besides, the simulated maximum gain reaches −25.3 dBi.