Integrated Metal-Frame Antenna for Smartwatch Wearable Device

A design concept of integrating the loop antenna into the front metal frame of a smartwatch Bluetooth device is introduced. The antenna was constructed from a 0.3-mm-thick, rectangular metal frame with a dimension of 5 mm × 40 mm × 50 mm, which encircled the system circuit board of the watch. A separation distance of 2 mm between the loop and the system ground plane was also set to alleviate the strong coupling between the antenna and the ground. With the signal feeding fixed in the middle of either one of the frame´s longer edges and followed by shorting the loop in a proper location, the antenna can easily cover the 2.4-GHz band (2400-2485 MHz) for Bluetooth operation. The design and the results thereof are described and discussed in the article.