On-body antenna with reconfigurable radiation pattern

On body antenna design is a challenging task due to the body being in the near-field of the antenna and the interaction between the two. The antenna should be designed to have a more application dependent gain pattern and to be less sensitive to near field effects of the body. For the case of on-body links, the antenna radiation should be directed along the body with an omni-directional pattern in horizontal plane of the antenna. It should preferably have vertical polarization. For the case of off-body links, the antenna radiation should be directed away from the body while the polarisation is not as critical as the on-body case. This paper presents a novel antenna design tackling the aforementioned challenges by exciting TM₀₀ mode of a shorted rectangular patch antenna for the on-body link and exciting the TM₀₁ mode for the off-body links. By means of a switching mechanism, either the on-body operation or the off-body operation is activated at 2.45 GHz with 64% and 75% efficiency respectively.