A 2.4GHz Electrically Small Antenna for IoT Terminals

A low-cost planar Electrically Small Antenna (ESA) for narrow-band IoT terminals is presented. The ESA is based on a loop whose first anti-resonance is utilized for impedance matching. Its excitation mechanism reinforces its magnetic mode while suppressing its electric dipole modes to achieve an end-fire omni-directional pattern. A 2.4GHz prototype is designed and simulated. It achieves excellent return loss with 53% total radiation efficiency at 2.445GHz. An active prototype is also designed where the ESA is fed by a chip oscillator.