Dielectric Leakage Attacks on Liquid Crystal Phase Shifters in 60 GHz WiGig Systems

In this letter, the susceptibility and resilience of malicious dielectric-leakage attacks on a liquid crystal (LC)-based strip line phase shifter targeting 60 GHz WiGig beam-steering applications are measured for the first time. An extreme scenario of total dielectric leakage attack, that is the cavity becoming air-filled, is examined for two designs of the LC-filled strip line geometry. The vulnerability assessment indicates a measured return loss increase of 10.63 dB and a characteristic impedance drift of 40.55 Ω for the design geometry that is impedance-matched to 50 Ω at the saturated bias state of the LC. In contrast, for the design matched at the 0 V biasing state of the LC, the measured drifts are comparatively lower, with a return loss increase of 7.19 dB and the impedance variation of 28.77 Ω, featuring reduced susceptibility to dielectric leakage-induced perturbations. Impactfully, the undesirable amplitude drifts in the transmitted signal, induced by LC leakage attacks, can significantly impact the feeding of antenna elements in beam-steering systems. Such perturbations may lead to underestimated security vulnerabilities, including potential eavesdropping risks, particularly in mission-critical sensing and communication applications.