Wearable antenna design on finite-size high impedance surfaces for smart-watch applications

This paper presents a suspended microstrip-line method which is particularly suitable for characterization of finite-size high impedance surfaces (HISs). Conventionally, HISs are characterized by the reflected phase of the unit-cell structure; however, as the design space of HIS is given and finite, it is found that the operational frequency identified by the periodic unit-cell simulation cannot be straightforwardly applied to the case with finite-size HIS. In this work, we propose an antenna along with a finite-size HIS for smart-watch applications. The HIS of size 38 × 38 mm² is developed, and the operational frequency band is characterized by the suspended microstrip-line method. As a result, the finite-size HIS is successfully constructed, and antenna performances can be greatly enhanced by this finite-size HIS.