Direction Finding Antenna using Rotating Radome

Unmanned Aerial Systems (UAS) are vulnerable to a number of cyber-attacks. To navigate and avoid collisions, they rely on accurate information from GPS and Automatic Dependent Surveillance-Broadcast devices. Signals of these devices are can be jammed, spoofed, deleted, and modified. Identifying the location of an attacker can detect and mitigate cyber-attacks. This paper proposes a novel approach to identifying the angle of arrival of a signal. The approach consists of using a spinning radome with an attenuating, parasitic, section. The attenuating section spins around to create a periodic amplitude modulation on the received signal while not breaking the communication link. The amplitude of the signal drops when the attenuating section is in-line with the transmitter attacker. When the received signal is the lowest, the angle of the radome attenuator corresponds to the angle of arrival of the signal of interest. The results show that by using two measurements of the angle of arrival at different locations, one can calculate the attacker/transmitter's location with good precision. Two radomes were used for measurements at various locations.