Wearable antennas for FM reception

The effect of human body on wearable 100 MHz antennas is studied by measurements. At that frequency, the body is very thin compared to the wavelength, but about half a wavelength tall. Antenna performance is most affected by the posture of the antenna wearer, second matter being antenna position on body. Physical traits of the wearer have only a slight effect on the antenna performance. A -13 dBi gain was achieved by the constructed dipole-like antennas, and letting one's arms hang down reduces this by 5 to 15 dB. Most of the power delivered to the antennas is absorbed by the human body, but some is radiated not only by the antenna but also by the body. Wearable antennas need to be shortened by 15 to 25 % from the free-space length to achieve the desired resonance frequency.