Electrically Small UAV Antenna Design Using Characteristic Modes

This paper presents a novel concept of antenna design for an electrically small unmanned aerial vehicle (UAV) using the theory of characteristic modes. With the knowledge of the characteristic modes of the UAV body, a multi-objective evolutionary algorithmis implemented to synthesize currents on the UAV body for achieving desired power patterns. Compact and low-profile feed structures are then designed to excite the synthesized currents. The feed structures are termed as probes, as they are used to excite the currents on the UAV body and cannot work as standalone antennas. The UAV body excited by these probes serves as the radiating aperture. Its reconfigurable radiation patterns are obtained by feeding each probe with proper magnitude and phase. In this method, the aperture of the UAV body is fully utilized. Practical issues associated with large antennas at low frequency band are eliminated. Knowledge for probe placement on such platform becomes more explicit. Simulated and measured results are presented to verify the design concept.