Slot antenna for all-metal smartwatch applications

A circular slot-antenna designed for uses in smartwatches with all-metal for 2.4G BT/WIFI applications is presented in this paper. The model of smartwatch used for studies has a housing and wristband, both made of metal only. The smartwatch housing has a cylindrical shape with a circular-surface area of π×23
²
mm
²
and a height of 10 mm, occupying a total volume of π×23
²
×10 mm
³
. The circular slot antenna is formed using an arc-shaped slot with a length of 97 mm and a width of 1 mm along the edge of the circular surface of the smartwatch housing. Computer simulation is used to study the performance of the slot antenna in free space and on a phantom hand. Results of studies show that the slot antenna has the impedance frequency bands of 2.4–2.55 GHz and 2.35–2.5 GHz in free space and on the phantom hand, respectively, to cover the 2.4G BT/WIFI system. The efficiency of the antenna can reach more than 65% even on the phantom hand, making the slot antenna a suitable candidate for all-metal smartwatch applications.