Optimization and Validation of a Tunable Plasma-Based Super Lens for Sub-Wavelength Millimeter-Wave Imaging using Taguchi Statistical Design Method

Conventional electromagnetic imaging is fundamentally constrained by the diffraction limit, which restricts resolution to approximately half the operational wavelength (λ/2). This paper presents the design, computational modeling, and experimental validation of a Plasma Perfect Lens (PPL) engineered to overcome these limitations in the millimeter-wave regime (below 10 GHz). By utilizing a continuous, atmospheric-pressure plasma sheet as a dynamic metamaterial, the system achieves tunable negative permittivity and negative permeability, the latter induced through super-imposed high-voltage inductive modulation. To optimize imaging performance, a Taguchi-style Design of Experiment (DOE) was implemented using an L9(34) orthogonal array, evaluating factors including electron density (ne), lens thickness (d), and modulation parameters. Statistical Analysis of Means (ANOM) and Analysis of Variance (ANOVA) identified electron density as the primary driver of resolution. The results demonstrate that an optimized configuration—characterized by ne = 1012 cm−3 and a sub-wavelength thickness of 10 mm—achieves a focal spot size of 0.38λ, successfully beating the classical diffraction boundary with a positive transmission gain of +4.2 dB. These findings, supported by the research ecosystem in Riyadh, Saudi Arabia, provide a robust framework for high-resolution applications in telemedicine, secure communications, and non-destructive industrial evaluation.