Geometric diversity versus frequency diversity an imaging example

In classical radar, frequency diversity offers one method of obtaining additional information about targets. With the most basic form of frequency diversity, namely increased bandwidth, high range resolution is afforded to the user. Geometric diversity can also offer the potential for increased resolution, and is the multi-static dual to frequency diversity (increased bandwidth) in classical mono-static radar. In the extreme case, 360 degrees of geometric diversity (tomography) offers sub-wavelength resolution, even under the monochromatic assumption. Operational constraints can limit the system performance. Frequency diversity and geometric diversity can be used in various combinations to obtain the best image under these constraints. For example, frequency allocation can limit the available bandwidth. Geometric diversity with a single or multiple narrowband signals can provide the required system performance. Imaging performance can be evaluated using two factors: resolution and target dynamic range. Resolution is the ability to distinguish two closely separated targets and dynamic range is the ability to determine the presence of a ´weak´ target in the presence of a ´strong´ target.