Bandwidth enlargement of low-profile slot antenna using ground resonance mode

In this paper, we propose a method to increase the coupling between the ground and the antenna to improve the radiation performance of the mobile antenna. By adjusting the length of the slot antenna located at the center of the 48 mm x 15 mm ground resonating at 2.45 GHz, the coupling between the ground and the antenna can be controlled. When the coupling between the ground and the antenna is sufficiently strong, the ground resonance mode is strongly excited and a better radiation performance can be obtained. As the length of the slot antenna increases from 5 to 10 mm, the coupling between the ground and the antenna becomes stronger and the impedance bandwidth of -10 dB at 2.45 GHz becomes five times wider from 160 MHz (6.5%) to 780 MHz (31.8%).