Design and implementation of ground station antennas for UAV data radio link in UHF band

Design and implementation of ground station (GS) antennas are presented to control UAV by use of data radio link between UAV and GS based on spread spectrum in frequency band of 780-880MHz at the maximum range of 100Km. Gain, frequency bandwidth, polarization, radiation pattern, and the height of installed antenna from the ground are very important in regard to UAV maneuver and desired range. Helix and omni-directional antennas are designed and implemented to cover short and long ranges. Helix is designed based on Emerson's relations and optimized by IE3D to match to 50Omega in frequency range of 100MHz by new stub-loaded method. Monopole antenna is designed and optimized by Fidelity software. After implementation, measurement results are in a good agreement with the simulation. Then, we demonstrate how we can dominate the ground effect and multipath effect by use of two-antenna system.