Resonant substrate-integrated near-field sensors with improved sensitivity

The sensitivity of near-field sensors with substrate-integrated waveguide (SIW) resonator is studied. The structure of the sensors is based on a folded cylindrical cavity. Its shape and size are varied by exploiting the field symmetry of the excited mode. The resulting mode transformation is discussed. Several sensors of different geometries with resonant frequency close to 8 GHz are analyzed with respect to their sensitivity to ethanol and water. By adequately choosing the shape the sensitivity of the sensor, i.e., the shift of its resonant frequency caused by a dielectric sample, can be increased significantly.