N251-001 Directional High Front to Back Ratio Low Frequency Antenna

High-frequency (HF) communications remain a critical capability for the United States Marine Corps (USMC), enabling long-range, beyond-line-of-sight (BLOS) communications and radar functions in contested and denied environments using primarily terrestrial hardware. HF communications offer a resiliency that operate independently of space-based infrastructure. Traditional omnidirectional HF antenna systems present operational limitations, including increased electromagnetic interference (EMI) risks, greater susceptibility to enemy signals intelligence (SIGINT) detection, and inefficient power utilization. Additionally, typical HF solutions are generally large structures that require complicated and lengthy setup time and often provide limited bandwidth. To enhance operational performance and improve security and efficiency, there is a growing demand for directive HF antenna technologies that are lightweight, compact, and broadband. FIRST RF’s proposed approach leverages a foundation of proven HF antenna technologies and design philosophies that have shown to significantly improve HF capabilities. Most notably is a novel application of reactive loading that significantly reduces the physical size of the antenna without compromising bandwidth or efficiency. Additionally, to achieve directional gain coverage with a front-to-back ratio more than 30 dB, FIRST RF’s proposed approach implements a two-element array such that the phase between the two elements forms a perfect null in the opposite direction of intended emissions.