Performance enhancement of ground radiation antenna by coupling with ground body

Abstract

In this paper, the effect of coupling between the antenna and ground characteristic mode is investigated by comparing the radiation performance of antennas located inside and outside the ground plane. In general, it is understood that an antenna occupying a larger space has better radiation performance. However, in this paper, it is shown that coupling between the antenna and ground is important for radiation performance, rather than the size occupied by the antenna. The antenna is strongly coupled with the ground characteristic mode when located inside the ground; the -10 dB bandwidth is 130 MHz at 2.45 GHz, and the measured realized efficiency is -0.64 dB in the 2.4-2.5 GHz band. When the antenna protrudes from the ground plane, the coupling between the antenna and the ground characteristic mode is weak, achieving a narrower -10 dB bandwidth of 50 MHz at 2.45 GHz, and lower measured realized efficiency of -2.20 dB in the 2.4-2.5 GHz band. In other words, the radiation performance of the same antenna is significantly influenced by the coupling with the ground.