Substrate integrated resonant near-field sensor for material characterization
A compact near-field sensor for material characterization is proposed. It is composed of a substrate integrated waveguide resonator with coplanar waveguide interfaces, thus enabling easy integration and advanced multilayer technology. The material under test (MUT) is sensed by a tiny tip protruding from the resonator. If placed near this tip the MUT sensitively detunes the sensor. The response can be translated into precise, local permittivity information. As simulation shows microscopic applications seem possible thanks to the near-field character and the small effective scanning volume of the sensor. Measurements at X- and K-band frequencies confirm the general functioning of the sensor and demonstrate good principal agreement with simulation.