Embedded antenna design on LoRa radio for IoT applications

This paper presents a miniaturized printed inverted-F antenna (PIFA) embedded on the circuit board of a LoRa sensor node for the internet of things (IoT) applications. On the 1.6 mm-thick board, very limited space is reserved for the antenna deployment, and therefore slots are cut on the ground to reduce operating frequency of the PIFA and create another resonance to broaden the bandwidth. Finally, the proposed antenna is optimized to operate from 402.4 MHz to 441.6 MHz with voltage standing wave ratio (VSWR) less than 3, and its realized gain over the 410–441 MHz LoRa frequency band is higher than −6 dBi.