Dual band low profile antenna for body centric communications with a split ring resonator

A dual band low profile antenna for wireless body centric communications is presented in this paper. It is composed of a zeroth-order loop loaded periodically with mu-negative transmission line (MNG-TL) and a circular patch located in the center of loop. The MNG-TL loop based on the fundamental infinite wavelength property allows current along the loop to remain in phase and same magnitude so that a highly efficient and miniature loop antenna with omni-directional pattern in azimuth plane at low frequency band for on-body communications is generated. On the other hand, a unidirectional pattern in elevation plane at upper frequency band for off-body communications is also obtained by circular patch simultaneously. In order to improve the pattern in azimuth plane, a split ring resonator (SRR) element is used to direct the electromagnetic field propagation. By placing a single SRR at the near field of the loop in different location, the mechanic of function between SRR and loop is also presented.