The integration of a loop antenna into the top metal frame of a smartwatch wearable device is introduced. The loop antenna was made of a 1-mm thick, rectangular metal frame, which was stacked 1.5 mm above the lower metal frame of the watch having a size of 7 mm × 35 mm × 40 mm. The system circuit board was encircled by the lower, rectangular metal frame with a 1 mm gap between the perimeter of the ground plane and the metal frame. The top metal frame was fed in a corner on the frame's longer edge with two shorting portions short-circuited to the system ground. By carefully positioning the two shorting for the top metal frame, the proposed loop antenna can provide the global positioning system (GPS) operation at 1575 MHz for smartwatch applications.
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