Low-profile horizontal omni-directional antenna for LoRa wearable devices

In this paper, a novel antenna suitable for wearable LoRa devices is introduced. Its size is just 42.5 × 45 mm
²
, similar to the size of a watch, thanks to the advantage of a wire-patch antenna structure. The proposed antenna operates at 868MHz frequency band with the realized gain up to 0.4 dBi. This antenna is proved to be better than former designs by obtaining azimuthal polarization which reduces effects from human body. In addition, its polarization is circular, thus loss from polarization mismatch is expected to be minimized.