  It is widely believed that range resolution, the ability to distinguish
between two closely situated targets, depends inversely on the bandwidth of the
transmitted radar signal. Here we demonstrate a different type of ranging
system, which possesses superior range resolution that is almost completely
free of bandwidth limitations. By sweeping over the coherence length of the
transmitted signal, the partially coherent radar experimentally demonstrates an
improvement of over an order of magnitude in resolving targets, compared to
standard coherent radars with the same bandwidth.. A theoretical framework is
developed to show that the resolution could be further improved without a
bound, revealing a tradeoff between bandwidth and sweep time. This concept
offers solutions to problems which require high range resolution and accuracy
but available bandwidth is limited, as is the case for the autonomous car
industry, optical imaging, and astronomy to name just few.
