Null-filled Shaped Beam Horizontally Polarized Omnidirectional Antenna

In this paper, a compact, mechanically rugged, DC grounded Null-filled horizontally polarized antenna having low gain ripple in the omnidirectional pattern is proposed for UAV Ground Command Station. The antenna is based on the coaxial cylinder structures, which consists of oversize coaxial cylinders, slots and their feeding assembly and a matching unit. The horizontal polarization property is realized by four vertical slots surrounding the axis of the coaxial cylinder in the outer conductor. The antenna is dc ground which eliminates the electrostatic discharge ESD problems. Simulation results show that the antenna bandwidth is 8.1% (2.56 GHz to 2.78 GHz respectively, gain variation in the horizontal plane is less than ±1 dB while the cross-polarization level is below 15 dB over the whole bandwidths.