Plastronics Development of Low-Profile Conformal Antenna for IoT Sensors

A compact and conformal cylindrical antenna for IoT sensor applications is presented. Plastronics development using Laser Direct Structuring (LDS) process is carried on to optimize the space occupied by the antenna. Specific LDS-compatible polycarbonate (PC) thermoplastic is used as a substrate. The dipole antenna stands on the outer surface of a 17 mm high cylinder with a diameter of 48 mm. The antenna operates in the European ISM band (868 MHz), which implies a very low profile length dimension of (0.14 λ)2. The cylindrical holder is mounted in an industrial light fixture in order to be connected to a compact sensor board. Good agreement between simulations and measurements is found with a dipole-like radiation pattern and a maximum of 1.32 dBi measured gain. The 22 MHz bandwidth (S11 < -10 dB) satisfies the European ISM band IoT protocols LoRa.