NVIS synthesis for electrically small aircraft using characteristic modes

Characteristic modes are used to design a multi-antenna NVIS system on-board an electrically small UAV. By analyzing the radiation eigenmodes of the UAV platform, optimal NVIS patterns are constructed, and mounting locations which maximize desirable antenna-platform coupling are identified. The optimal NVIS pattern is then approximated using discrete monopole antennas as feeding elements. The excitation level of each feed can be inferred by relative excitation of each UAV characteristic mode in the NVIS pattern. Discussions on the pattern accuracy, bandwidth, and efficiency of this approach as a function of feeding element number will be presented.