Bandwidth enhancement of HF antennas mounted on military platforms using a Characteristic-Modes-Based Design Approach

Narrow bandwidth is a challenging problem for designing platform-mounted electrically small antennas in the high-frequency (HF) band. In this paper, we demonstrate a process that can be used to improve the bandwidth of a platform-mounted HF antenna or antennas by taking advantage of the presence of the platform. Specifically, we examine a simplified model for the Expeditionary Fighting Vehicle (EFV) and examine how the mounted antennas can be used to excite a desired natural resonant mode of this platform for bandwidth enhancement. The proposed approach is employed to successfully enhance the bandwidth of horizontally-polarized HF loop antennas from 0.64% to 0.79% and 0.89%, by using respectively one, two, or four half loop antennas to excite the desired mode of the EFV.