RESUMEN
This paper describes an innovative remote surface sterilization approach applicable to the new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The process is based on the application of a liquid film on the surface or object under sterilization (OUS). A beacon signal is used to self-steer the transmitted power from the designed retrodirective antenna array (RDA) towards the OUS using circularly polarized fields; then, the sterilization is completed by raising and maintaining the required temperature for a certain time. Results suggest that the process takes 5 minutes or less for an angular coverage range over 60 degrees whilst abiding by the relevant safety protocols. This paper also models the power incident onto the OUS, providing consistent results with full-wave simulations. A practical RDA system is developed using a 2 × 1 microstrip patch array operating at 2.5 GHz and tested through the positioning of a representative target surface. Measurements, developed by sampling the power transmitted by the heterodyne RDA, are reported for various distances and angles, operating in the near-field of the system. To further validate the methodology, an additional experiment investigating virus deactivation through microwave heating was also developed. Measurements have been performed with an open cavity microwave oven on the Coronavirus (strain 229E) and egg white protein in a cuvette. This demonstrates that the temperature increases of aqueous films up to 70 [Formula: see text]C by remote microwave-induced heat can denature proteins and deactivate viruses. Possible applications of the method include sterilization of ambulances, medical equipment, and internet of things (IoT) devices.
RESUMEN
A low-cost compact planar leaky-wave antenna (LWA) is proposed offering directive broadside radiation over a significantly wide bandwidth. The design is based on an annular metallic strip grating (MSG) configuration, placed on top of a dual-layer grounded dielectric substrate. This defines a new two-layer parallel-plate open waveguide, whose operational principles are accurately investigated. To assist in our antenna design, a method-of-moments dispersion analysis has been developed to characterize the relevant TM and TE modes of the perturbed guiding structure. By proper selection of the MSG for a fabricated prototype and its supporting dielectric layers as well as the practical TM antenna feed embedded in the bottom ground plane, far-field pencil-beam patterns are observed at broadside and over a wide frequency range, i.e., from 21.9 GHz to 23.9 GHz, defining a radiating percentage bandwidth of more than 8.5%. This can be explained by a dominantly excited TM mode, with low dispersion, employed to generate a two-sided far-field beam pattern which combines to produce a single beam at broadside over frequency. Some applications of this planar antenna include radar and satellite communications at microwave and millimeter-wave frequencies as well as future 5G communication devices and wireless power transmission systems.