Triple-Band Loop Antenna for 5G/WLAN Unbroken-Metal-Rimmed Smartwatch

A design concept of integrating the loop antenna into the inner metal frame of a smartwatch for 5G/WLAN application is introduced. The antenna is constructed from a rectangular metal frame which encircled the system circuit board of the watch. A separation distance between the loop and the system ground plane is set to alleviate the strong coupling between the antenna and the ground. The antenna can easily cover the 2.4-GHz band (2400-2485 MHz) for WLAN operation, 3.4-GHz band (3300-3600 MHz) and 4.9-GHz band (4800-5000 MHz) for 5G application in China. Simulated results show that the antenna has an efficiency of 67%-91 % in these operation bands.