Dual-band 4G eyewear antenna and SAR implications

This paper presents low-cost and easy-to-manufacture dual-band antenna solution to achieve cellular 4G (LTE-Advanced) coverage in smart eyewear devices. Coupling element type antenna has been evaluated with appropriate matching networks to cover the target bands of 700-960MHz and 1.7-2.7GHz. To emulate a realistic device, an ABS plastic dielectric frame has been designed and manufactured using 3D printing technology. Simulations for the antenna are carried out in three typical use-case scenarios which are "with user's head", "with head and hand" and "free space". The simulations are validated through S-parameters, efficiency and radiation pattern measurements using fabricated frame and antenna prototype in the presence of head and hand phantoms. The SAR behavior of the antenna designs is also investigated through simulations and measurements. It is demonstrated that SAR values are found to be above the limitations which might be problematic in practical use if the transmit power of the eyewear is not reduced.