A Planar Low-Cost Electrically Small Antenna For NB-IoT Sensors

A low-cost planar Electrically Small Antenna (ESA) is presented. The ESA is designed for operation at 1.8 GHz which makes it suitable for integration with loT devices that utilize Narrow-Band loT (NB-IoT) protocol. To allow for reliable power reception, a suitable feeding structure is designed with the aid of characteristic modes to excite a magnetic mode leading to a horizontal omnidirectional pattern. The design is realized using the two layers of a commercially available low-cost substrate and is fed using a twin line balanced configuration to mitigate the effects of common-mode radiation. The ESA has ka of 0.47, a realized gain of -0.4 dB and a simulated total efficiency of 60%. It is suitable for integration with circuits to develop a compact communication system for loT sensors without changing the antenna's radiation pattern.