  This paper deals with propagation and channel modeling for physically large
arrays. The focus lies on acquiring a spatially consistent model, which is
essential, especially for positioning and sensing applications. Ultra-wideband,
synthetic array measurement data have been acquired with large positioning
devices to support this research. We present a modified multipath channel model
that accounts for a varying visibility of multipath components along a large
array. Based on a geometric model of the measurement environment, we analyze
the visibility of specular components. We show that, depending on the size of
the reflecting surface, geometric visibility and amplitude estimates obtained
with a super-resolution channel estimation algorithm show a strong
correspondence. Furthermore, we highlight the capabilities of the developed
synthetic array measurement system.
