Temperature-Sensitive Microstrip Patch Antenna Radiation using Large-Area Artificially-Engineered Carbon-Loaded Composites

Wireless antenna-based sensors are a key enabler of integrated sensing and communications. Nevertheless, materials are yet to be developed for RF sensing. Herein, we present a detailed analysis of the radiation and material properties of a temperature-sensing microstrip patch antenna, based on the first large-area thermistor substrate. Owing to the substrate's behavior as a positive temperature coefficient (PTC) thermistor, up to two orders of magnitude variation is observed in the RF conductivity from 10 MHz to 4 GHz. Furthermore, the substrate's permittivity undergoes up to a five-fold change between room temperature and 240° C. Over 20 dB gain change is measured in the broadside direction for a 140° C temperature increase, resulting in a best-in-class sensitivity of 0.16 dB/°C. The results show that large-area sensing substrates could improve the performance antenna-based sensors beyond state-of-the-start.