Inexpensive fabric antenna for off-body wireless sensor communication

Emerging trends in monitoring people (patients, soldiers, athletes, etc.) have led to numerous recent advances in body area communication networks (BAN). Wireless sensor communication opens up tremendous potential for wireless patient monitoring. Body centric wireless networks use RF sensor nodes in close proximity to the human body. Body networks include on body, body to body and off body communication. Antenna design and analysis plays an important part in the development of sensors for BAN. Antennas for on-body communication include the inverted F antenna, (IFA) and the planar inverted F antenna (PIFA), low profile microstrip patch antenna, sleeve dipole, printed-F antenna, wearable (fabric) antennas, broadband discone antennas etc.. In this paper we discuss a low cost, nearly circularly polarized truncated patch antenna design on Zelt fabric and Felt substrate for performing offbody communication centered at 915 MHz for monitoring patients after operation. This low cost antenna provides good return loss and high directivity and efficiency comparable to the fabric antennas designed in the literature. The antenna also has a 10-dB bandwidth of 75 MHz which accounts for the frequency shifting due to the bending of the antenna.