Performance analysis of wearable microstrip antennas with low-conductivity materials

This paper has presented a 2.4-GHz WLAN rectangular microstrip textile antenna design, along with investigations of the degradation in resonant, matching, and gain properties of the antenna if low conductivity materials are used for all conductors in the structure. The results show that the resonant frequency remains almost the same for lower conductivities, and that the reflection from the antenna port is even smaller for conductivities on the order of 10⁵ S/m than for copper conductors, the mismatch losses increase to prohibitive levels for conductivities on the order of 10³ S/m. The antenna gain attains reasonable values for sigma ~10⁵ S/m. However, for conductors with sigma ~ 10³ S/m, the conductor losses dominate the radiated power, resulting in practically unacceptable gain levels. Overall, conductivity levels of WLAN microstrip textile antennas must be in excess of ~10⁴ S/m for an acceptable antenna performance in wearable applications.