Microwave Detection of Carbon Monoxide Gas via a Spoof Localized Surface Plasmons-Enhanced Cavity Antenna

This paper presents a carbon monoxide (CO) detection mechanism achieved through further improvement of the sensing antenna based on hybrid spoof localized surface plasmons (SLSPs) and cavity resonance. Unlike conventional approaches relying on chemical reactions or photoelectric effects, the all-metal configuration detects dielectric variations through microwave-regime resonance frequency shifts, enabling CO/air differentiation with theoretically enhanced robustness and environmental adaptability. The designed system achieves measured figures of merit (FoMs) of 183.2 RIU^-1, resolving gases with dielectric contrast below 0.1%. Experimental validation successfully discriminated CO (ε_r = 1.00262) from air (ε_r = 1.00054) under standard atmospheric pressure at 18 °C.