Novel flexible materials for wearable antennas

The emergence of wearable intelligent systems has benefited from high performance antennas which are primarily used for communication purposes including monitoring of patients in hospitals, defence, navigation, tracking and public safety. Conventional antennas have often consisted of a laminate and ceramic materials. Those conventional materials have typical drawbacks including but not limited to being hard and brittle, lacking in flexibility, and being vulnerable to impact which may lead to breakage or variation in performance. The material characterization in related design aspects involving antenna theory and computer-assisted design with state of the art electromagnetic simulations tools are discussed in this project. The substrates should be lightweight and robust for the realization of various types of wearable antennas with an aim to achieve good results without much variation in performance.

In this paper, the available dielectric materials bought and measured include felt, fleece, foam, leather and rubber with relative permittivity range from 1.21 to 6.50 achievable in which the best and worst losses need to be compromised. Two types of antennas for operation in the industrial, scientific and medical frequency band (ISM band) will be considered. The first one is an omnidirectional flatmonopole type antenna, based on a square substrate integrated cavity radiating between four eyelets shorting. The antennas effectively create a square loop of magnetic currents along the length of the patch. The radiation patterns have an omnidirectional radiation as an electric monopole in a fundamental TM11 mode with resonant frequency of 2.45 GHz. The second one is a directive PIFA-type antenna with two eyelets shorting in the aperture of three side walls. The two types of applications of the omni and directional antennas are on-body communication between sensors and off-body communication to a base station. The ongoing fabricated prototypes need to be tested to compare with the simulation and designation.