Ultraminiaturized Metamaterial-Inspired SIW Textile Antenna for Off-Body Applications

This letter introduces a novel miniaturized cavitybacked substrate integratedwaveguide textile antenna for off-body applications in the 2.45 GHz industrial, scientific, and medical radio band. The use of metamaterial-inspired slots reduces the antenna size by 80% compared to previous works, and the radiation pattern is broadside toward the normal direction. The simulated and measured results are presented for both free space and the human body, and show good impedance matching for both normal and curved models. The measured gain and efficiency of the structure were 5.35 dBi and 74.3%, respectively, and the effect of the antenna on the human body was measured using a skin equivalent phantom. The maximum numerically calculated specific absorption rate in the human body model over 10 g of tissue was 0.38 W/kg, on average, for 500 mW of input power, which is less than the 2 W/kg European limit. The design and configuration of the antenna make it a suitable choice for off-body applications.