Omni-Directional Small Planar Antenna Composed Of Folded Slots Spanning Over Both Sides

A small planar antenna composed of folded slots is proposed for mobile communications, especially for being mounted on unmanned aerial vehicles (UAVs). Bending slits are made rotationally symmetrically on top and bottom sides of a printed circuit board. The slits are joined in pairs via open edges of the printed board to form slots spanning over both the sides. The directivity is omni-directional and the polarization is dominantly horizontal. The antenna can be controllably miniaturized by being made of a thinner substrate because the resonant frequency decreases as the substrate thickness decreases. Influence of an adjacent conductor plate is examined for the actual usages of being mounted on UAVs and mobile terminals.