ABSTRACT
This chapter presents the analysis and measurements of wearable antennas in the vicinity of a human body. The electrical properties of human body tissues have a significant effect on the electrical characteristics of wearable antennas. The antenna’s input impedance variation as a function of distance from a body was computed by employing electromagnetic software. The antenna’s radiation characteristics on a human body have been measured by using a phantom. The phantom’s electrical characteristics represent a human body’s electrical characteristics. The phantom contains a mix of 55% water, 44% sugar and 1% salt. The antenna under test was placed on the phantom during the measurement of the antenna’s radiation characteristics. S11 and S12 parameters were measured directly on human body by using a network analyzer. The measured results were compared to a known reference antenna.
The antenna S11 results for different belt thicknesses, shirt thicknesses and air spacing between the antennas and a human body are presented in this chapter. If the air spacing between the dual polarized antenna and the human body is increased from 0 to 5 mm, the antenna’s resonant frequency is shifted by 5%.
