This book covers all aspects of foliage penetration (FOPEN) radar for both airborne military systems and earth resource mapping. It is the first book to be published on this subject and is the result of a decade-long investment by the Defense Advanced Research Projects Agency (DARPA) into characterizing foliage and earth surface with ultrawideband UHF and VHF synthetic aperture radar. Military radar systems engineers will use this book for discovering methods allowing them to use ultrawideband waveform design and analysis for generating signals that do not interfere with emergency or flight safety frequencies and adaptive processing techniques to reconstruct signals in a dense radio frequency interference environment. They will also learn the characteristics of clutter, foliage scattering and propagation that affects the detection and characterization of vehicles, buildings, and terrain features that are present under trees. In addition, extensive information is given on image formation processing with an emphasis on use of real time high performance processing, change detection, and automatic target detection and classification. Adaptive processing to remove the effects of radio and television signals from the system is also covered. Advanced topics include additional uses of FOPEN systems including: simultaneous SAR (synthetic aperture radar) and GMTI (ground moving target indication) operation; as well as bistatic SAR utilizing a FOPEN GMTI radars waveform. For decades, technology developed for military systems has found its way into commercial, societal, and environmental uses. This book will be the foundation reference for earth resource and remote monitoring planners for years to come as they apply FOPEN radar for crop monitoring, land mine remediation, creating digital maps under trees and many other uses that can benefit mankind.