RF-hardening of small UAS for mitigation of HIRF impacts

Abstract

The survivability of small Unmanned Aerial Systems (sUAS) in high-intensity electromagnetic environments (HIRF) is a significant characterization that determines the capabilities of UAS in critical operation situations. The existing small UAS system designs do not consider the complexity of adversary electromagnetic environments, such as Radio Frequency (RF) interference, electromagnetic interference (EMI), Counter-UAS (C-UAS) electromagnetic attack (EA), and other nearby sources of noises in spectrums. [1][2][3][4][5][6][7][8] This study aims to determine the feasible approaches that support the "hardening" of the existing S-UAS to counter or mitigate the impacts of HIRF and evaluate such improvements in both laboratory environments and flight tests. The first step is to identify the weak spots of the existing flight vehicles, from the propeller, motors, and controllers, as well as the internal electronics, especially the RF radios and power supplies. The second step is to emulate the HIRF environment we expect in multiple domains (such as air, sea, or ground airport) in laboratory environments. We are introducing a lab-based emulation testbed with higher power and better configurations than the previous work and installed it for the new emulation experiments. Thirdly, we perform careful power level measurements and calibrations and compare them to the theoretical models. The system setup and size focus on the S-band (near Wi-Fi band) radio links, electronic components, onboard GPS, and navigational sensors. At the same time, the same approach can be easily extended to other frequencies. From this study, we introduced three levels of mitigation measures. (1) Minimal protection. (2) Shielding solution. (3) Shielding and EMI filtering solution. We demonstrated how these levels of mitigation solutions affect the risk levels of survivability in the HIRF environments near high-power radars.