Investigation of the effect of metallic frames on 4G eyewear antennas

In this paper, we investigate the effect of metallic eyewear frames on the reflection coefficient, the radiation pattern and the specific absorption rate (SAR) of 4G antennas integrated in eyewear. The antennas used in the study are Coupling Element type, with appropriate matching networks to cover simultaneously the 700-960MHz and 1.7-2.7GHz frequency bands. Two different antenna locations are evaluated: behind the user´s ear and at the opposite corner of the printed circuit board, close to the eye. For both antennas, the effect of metallic frames is investigated through numerous simulations. Compared to the case without metallic frame, the matching and radiation patterns are slightly affected. Although there is a redistribution of the SAR hotspots inside the head, the change in the 1g and 10g SAR values are marginal as a result of including the metallic frame.