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An investigation of the deactivation of pathogens using electromagnetic waves in the microwave region of the spectrum is achieved using custom-built waveguide structures. The waveguides feature sub-wavelength gratings to allow the integration of an air cooling system without disturbing the internal propagating fields. The waveguides are tapered to accommodate an experimental sample internally with sufficient surrounding airflow. The proposed methodology allows for precise control over power densities due to the well-defined fundamental mode excited in each waveguide, in addition to temperature control of the sample due to microwave exposure over time. Human coronavirus (HCoV-229E) is investigated over the 0–40 GHz range, where a peak 3-log viral reduction is observed in the 15.0–19.5 GHz sub-band. We conclude HCoV-229E has an intrinsic resonance in this range, where nonthermal structure damage is optimal through the structure-resonant energy transfer effect.

Artificial magnetic conductor metasurface antennas are investigated using a robust, surrogateassisted, differential evolution optimization technique. Using a uniform metasurface array configuration as a starting point, multiple array configurations are parameterized and the differential evolution optimizer yields nonuniform array geometries exhibiting wideband performance. The bandwidth improvement is attributed to the structure's ability to support additional higher-order modes with good impedance matching. A comparison between the uniform metasurface antenna cases and their 'evolved' nonuniform counterparts is presented to demonstrate the advantages of the proposed technique. Two prototypes are fabricated and characterized to experimentally confirm the advantages of proposed designs. The first prototype, a 3x3 case, measured a fractional bandwidth of 36.8% with peak gain of 8.3 dBi. The second prototype, a 4x4 case, measured a fractional bandwidth of 51.8% with peak gain of 8.8 dBi. When compared to standard uniform cases, the proposed nonuniform geometries exhibit substantial impedance bandwidth enhancement.

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