  As new wireless standards are developed, the use of higher operation
frequencies comes in hand with new use cases and propagation effects that
differ from the well-established state of the art. Numerous stochastic fading
models have recently emerged under the umbrella of generalized fading
conditions, to provide a fine-grain characterization of propagation channels in
the mmWave and sub-THz bands. For the first time in literature, this work
carries out an experimental validation of a class of such ray-based models, in
a wide range of propagation conditions (anechoic, reverberation and indoor) at
mmWave bands. We show that the independently fluctuating two-ray (IFTR) model
has good capabilities to recreate rather dissimilar environments with high
accuracy. We also put forth that the key limitations of the IFTR model arise in
the presence of reduced diffuse propagation, and also due to a limited phase
variability for the dominant specular components.
