An investigation into the use of innovative ground-based microwave radar architectures for estimating snow properties

Snow is a very important environmental variable and a primary water resource in many areas of the world. Monitoring seasonal snowpack properties is crucial for properly managing snow-related hazards such as snow avalanches and snowmelt-floods. Microwave radars have been proposed as a means to non-destructively monitor snowpacks, but they have invariably employed external aids or a-priori assumptions to calculate key physical parameters of snow, such as total snow depth, snow density, snow water equivalent, and so on. This main contribution of this thesis is the proposal, design, implementation and experimental validation of an innovative radar architecture intended for snowpack monitoring, based on the use of two receivers. The proposed device can deliver estimates of total depth and wave speed in the snowpack, for both dry and wet snow conditions, without being supplemented by any additional hypothesis or device. The radar can also provides a rough estimation of the internal stratigraphy of the snowpack in terms of layer thickness, layer density and (in a preliminary form) layer wetness. The device was verified in the field with either dry or wet snowpacks in experimental sites. Another contribution of this thesis is the proposal of a novel radar technique for self-standing calculation of the Snow Water Equivalent that can be applied to bi-static radars. This technique, based on the multipath propagation of the radar signal into the snowpack, only requires a radar with two fixed antennas without any other device, movement of the antennas, or a-priori empirical assumptions. Finally, in order to improve the performance of the radar architectures proposed, a novel antenna realized by three-dimensional printing methods has been developed and experimentally tested. The antenna is based on a double-ridge waveguide configuration and is realized with different infill percentage dielectric material. The dielectric material presents low losses and a relatively high dielectric constant, reducing the encumbrance of the radar system.