Passive Security Enhancement Schemes
Jianping An, Shuai Wang, Pingyue Yue, Gaofeng Pan · 2025
Passive security techniques strengthen satellite systems by reducing their vulnerability to threats without the need for active countermeasures. This chapter examines advanced antenna technologies, such as frequency-diverse arrays (FDAs), which generate angle-dependent beams to hinder eavesdropping; reconfigurable intelligent surfaces (RISs), which manipulate signal reflections to enhance legitimate links and suppress interference; and spread-spectrum techniques, which spread signals across wide bandwidths to resist jamming. It also covers AI-driven interference suppression, which uses adaptive filtering to mitigate narrowband disruptions. The chapter explains how these methods—from beamforming to waveform design—reduce exposure to interception and jamming, even in satellite environments with resource constraints, where power and computational limitations restrict the deployment of active defenses. The detailed analysis includes the technical mechanisms: for example, an FDA's frequency offset-induced beam scanning can thwart direction-finding, RIS's phase-adjustable elements can create signal nulls for intruders, and spread spectrum's low spectral density can obscure signals from unauthorized receivers. Practical applications such as military communications and secure broadcasting illustrate the effectiveness of these techniques in enhancing system robustness passively with minimal added complexity to satellite payloads.