A wideband differential directional antenna for head implants

This paper presents the design of a wideband differential antenna which is suitable for head implants. The antenna consists of a ground plane beneath the patches and a differential feeding structure, which provides the directional radiation with an ultra-thin design. The antenna is fabricated using LTCC technology with an overall size of 24 × 10 × 0.95 mm³. In order to ensure that the antenna is bio-compatible inside the head, a Teflon casing is constructed to house the antenna, wherein the head is modeled as a four-layered lossy structure. The antenna implanted in the head exhibits an impedance bandwidth of about 20% with a reference impedance of 100Ω at the center frequency of 4 GHz, the directivity of more than 5 dBi and the boresight gain of more than -8.3 dBi.