Linear Low Density Polyethylene (LLDPE) as Flexible Substrate for Wrist and Arm Antennas in C-Band

This paper focuses on the development and study of linear low density polyethylene as a flexible substrate for conformal antennas for body-worn applications. Thermal stability, tensile strength and elongation at break of the substrate were studied. The permittivity of the substrate was 2.2 and tan delta was found to be 0.0003 at 6 GHz. Since the antenna is being developed for wrist and arm wearing in C-band, the performance of the antenna, such as the S (11) parameter and radiation pattern, were studied with different bending axes and with bending curvature approximating that of the arm and wrist. The performance of a 6 GHz rectangular patch antenna with bending was found to be consistent with the flat profile antenna at the same frequency. A maximum shift in the resonant frequency of similar to 20 MHz was observed. The -10 dB bandwidth and directivity of the antenna did not change much with bending. The maximum bending radius in the present study is 10 mm, and S (11) was found to be -17.53 dB at 5.94 GHz and -14.02 dB at 6.06 GHz for a bending axis parallel to the radiating and non-radiating edge, respectively.