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×232 mm2 and a height of 10 mm, occupying a total volume of π×232×10 mm3. 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.

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