Roberts balun based dipole design for tethered unmanned aerial vehicles

This paper presents a wideband dipole design based on Roberts balun for tethered Unmanned Aerial Vehicles (UAVs). It achieves vertical polarization, and omni-directional radiation. Its wideband performance is explained by using three-stage filter principle. The most importance feature of this antenna is that, it facilitates the cable powering the tethered UAVs to pass through this antenna, without affecting its electrical performance. Measured results show that this dipole antenna has better than 10 dB return-loss from 495 to 780 MHz, or about 44.7%. The diameter of the cylindrical dipole is approximately 0.046λ at the lowest frequency of 495 MHz, while its length is 0.478λ referred to the center frequency 637.5 MHz.