Foliage Penetration Radar (2021)

Foliage Penetration (FOPEN) Radar is a technical approach to find and characterize man-made objections under dense foliage, as well as characterizing the foliage itself. It has applications in both military surveillance and civilian geospatial imaging. This Tutorial is divided into three parts.

• The early history of FOPEN Radar: battlefield surveillance and the early experiments in foliage penetration radar are covered. There were some very interesting developments in radar technology that enabled our ability to detect fixed and moving objects under dense foliage. The most important part of that technology was the widespread awareness of the benefits of long dwell coherent radar and the advent of digital signal processing. Almost as important were the quantification of the radar propagation through foliage, and the impact of radio frequency interference on image quality. 
• FOPEN synthetic aperture radar (SAR) with concentration on development results and technology from several FOPEN systems. These systems were developed for both military and commercial applications, and during a time of rapid awareness of the need and ability to operate in a dense signal environment. The techniques developed for ultra wideband and ultra wide-angle image formation will be presented. Finally there is a clear benefit for use of polarization in the target characterization and false alarm mitigation. 
• New research in Multi-mode Ultra-Wideband Radar, with the design of both SAR and moving target indication (MTI) FOPEN systems. At common FOPEN frequencies, the systems have generally been either SAR or MTI due to the difficulties of obtaining either bandwidth or aperture characteristics for efficient operation. The last sections of the lecture will illustrate new technologies that are appearing in the literature with promise for future multimode operation.