Linearly Polarized Dipole Antenna and Antenna Array for LoRa Base-Station Applications

In this paper, a compact horizontally polarized microstrip based directional dipole element is proposed for LoRa applications. The presented dipole element is designed for compactness and efficiency by minimizing the side lobe level (SLL) in the radiation pattern. The dipole element is then used in an omnidirectional ring array antenna unit that is in turn used to construct a five-unit directional linear antenna array system for LoRaWAN base-station applications. The five-unit antenna array system demonstrates high directivity with a simulated gain of 9.5 dBi. Moreover, the omnidirectional unit shows satisfactory matching properties with a return loss value below -14 dB for both single-element and multi-element mode operation. A small antenna footprint was also achieved with the dimensions of the omnidirectional unit being smaller than the operating wavelength of 0.868 GHz.