Unmanned aerial vehicles (UAVs), also commonly known as drones, can be re-motely controlled without human onboard, and have advantages such as ease of de-ployment, low maintenance cost, high mobility, and ability to hover. Historically, UAVs were mainly used in military applications deployed in hostile territory for re-mote surveillance and armed attack, to reduce the pilot losses. In recent years, ad-vancement of UAVs’ manufacturing technologies and reducing cost have led to a surge in enthusiasm for using UAVs in civilian and commercial applications. In order for UAV to be used in various applications, the customized antenna for reliable and stable UAV-based wireless communications is required.
There are several conditions to consider when developing an antenna for UAV communications. First, a low-profile structure and low weight are required for cam-ouflage, efficient power management, and small air resistance. And in order to bal-ance the UAVs up, down, left and right, the antenna also needs a symmetrical bal-ance structure. Finally, in order to avoid discontinuous communication between UAVs and various devices, and to improve communication efficiency, it is necessary to have a wide beam coverage.
In this paper, a wideband printed half bow-tie antenna array with a quad-mode reconfigurable feeding network for UAV communications is presented. The pro-posed array consists of four printed half bow-tie antennas in the top substrate, two supports with a tapered balun, and a reflector with the reconfigurable feeding net-work in the bottom substrate. For UAV communications caused by wide beam coverage, the proposed reconfigurable feeding network using one single-pole-four-throw (SP4T) and two single-pole-three-throw (SP3T) switch-es can adjust the phase and amplitude to the antenna element. By controlling the switches, the proposed array can be operated on four linear polarization modes. The simulated and measured results prove the proposed array reconfigurability of the main beam in four directions with 45 steps in the azimuth plane. In addition, the pro-posed array achieves the wide 10-dB impedance bandwidth of approximately 29.6% (1507 MHz) from 4.1 to 5.6 GHz. The peak gain and half-power beamwidths (HPBWs) on azimuth and elevation planes of the proposed array are approximately 5.9 dBi, 240 , and 99 , respectively. The overall volume size of the proposed array is 60 × 60 × 18.3 mm3 (∼λ0 × λ0 × 0.3λ0 at 5.09 GHz).