From Wave Manipulation to Programmable Apertures: A Review of Metasurface-Enabled Radar

Electromagnetic wave manipulation underpins radar detection, imaging, and electronic countermeasures. Conventional phased-array and radio-frequency-chain-based radar architectures provide mature and high-performance operation but can face practical constraints related to aperture profile, power and thermal management, calibration, bandwidth, and multifunctional integration. Electromagnetic metasurfaces provide a complementary approach by controlling the phase, amplitude, polarization, and frequency content of scattered or radiated fields through subwavelength surface elements. This article presents a radar-system-oriented review of metasurface-enabled wave manipulation. We first summarize the relevant physical mechanisms, including generalized scattering, digital and information metasurfaces, time-varying modulation, and polarization and geometric-phase control. We then review experimentally reported applications in radar-cross-section control, programmable beam steering, computational imaging, time-modulated radar, multiple-input multiple-output systems, and integrated sensing and communication. Particular attention is given to the level of experimental validation and to the distinction between measured device- or subsystem-level performance and anticipated system-level benefits. Potential applications in stealth, radar deception, low-probability-of-intercept-oriented operation, and cognitive sensing are discussed together with limitations in bandwidth, efficiency, power handling, biasing, calibration, thermal management, and scalability. Overall, the available literature indicates that metasurfaces can support selected aperture-level radar functions, whereas general system-level advantages in SWaP, cost, latency, and energy efficiency remain to be established through controlled comparative experiments.