Dual-Antenna Concept With Complementary Radiation Patterns for Eyewear Applications

A dual-antenna concept to be integrated in a smart eyewear device is presented. The two antennas are printed on FR4 substrate and placed inside an Acrylonitrile butadiène styrène dielectric eyewear frame manufactured using 3-D printing technology. One of the two antennas is a monopole situated at the back of the eyewear with a specifically shaped ground plane underneath. The second antenna is a balanced-fed loop antenna placed in front of the eyewear with an integrated balun circuit. Both antennas are designed to operate in the 2.4 GHz band of the 802.11b/g/n standard. When compared to a reference single monopole antenna usually used in commercial eyewear, higher gain and complementary radiation patterns are obtained in several useful directions using our dual-antenna solution: 1) in front of the eyewear to communicate with a laptop; 2) in the side direction of the eyewear to communicate with a fixed hotspot access point; and 3) in downward direction of the eyewear to communicate with a peripheral smartphone in the pocket of the user. S-parameters and radiation pattern measurements are given with the eyewear placed over a specific anthropomorphic mannequin head phantom to validate the advantages of this novel dual-antenna concept. Specific absorption rate simulation results are presented showing the proposed antennas stay within the authorized limits.