Compact and wide-band antennas of omni-directional radiation

Abstract

Recent years have witnessed the explosive growth and demand for unmanned aerial vehicles (UAVs) in many applications. From military deployment to commercial sector and recreational activities. At the core of communication between the UAVs and ground station are the antennas hence the need for a compact and high bandwidth antenna is essential in providing high speed communication while not compromising the aerodynamic performance of the UAVs. A compact and wideband antenna of omnidirectional radiation is proposed in this project. The proposed antenna has a cylindrical structure consisting of a cone feeding element and top loaded with a ring that is shorted to the ground plane by 4 shorting lines. The proposed antenna is also loaded with dielectric material between the top ring and ground plane. The proposed antenna has a simulated height of 0.091λmax and diameter of 0.177λmax operating from 0.759 to 3.189 GHz which corresponds to 4.2:1 bandwidth. The simulated return loss is < -10 dB over the entire operating frequency band. The simulated radiation pattern is of omnidirectional in the azimuth plane (xy plane) and vertically polarized in the elevation plane (xz and yz plane) with the maximum realized gain of > 2.17 dBi and the antenna radiation efficiency of > 88.8%. The proposed antenna is fabricated and measured in the lab. Taking into consideration of the impedance mismatch factors, the antenna is of reasonable agreement between the simulation and measured results.