Radar MASINT

Radar MASINT is one of the subdisciplines of Measurement and Signature Intelligence (MASINT) and refers to intelligence gathering activities that bring together disparate elements that do not fit within the definitions of Signals Intelligence (SIGINT), Imagery Intelligence (IMINT), or Human Intelligence (HUMINT). See the main MASINT article for concepts that unify MASINT across its subdisciplines.

According to the United States Department of Defense, MASINT is technically derived intelligence (excluding traditional imagery IMINT and signals intelligence SIGINT) that – when collected, processed, and analyzed by dedicated MASINT systems – results in intelligence that detects, tracks, identifies, or describes the signatures (distinctive characteristics) of fixed or dynamic target sources. MASINT was recognized as a formal intelligence discipline in 1986.

As with many branches of MASINT, specific techniques may overlap with the six major conceptual disciplines of MASINT defined by the Center for MASINT Studies and Research, which divides MASINT into Electro-optical, Nuclear, Geophysical, Radar, Materials, and Radiofrequency disciplines.

Radar MASINT is complementary to SIGINT. While the ELINT subdiscipline of SIGINT analyzes the structure of radar directed on a target, radar MASINT is concerned with using specialized radar techniques that measure characteristics of targets. Another MASINT subdiscipline, Radiofrequency MASINT, considers the unintentional radiation emitted from a radar transmitter (e.g., sidelobes)

MASINT radar sensors may be on space, sea, air, and fixed or mobile platforms. Specialized MASINT radar techniques include line-of-sight (LOS), over-the-horizon, synthetic aperture (SAR), inverse synthetic aperture (ISAR) and multistatic. It involves the active or passive collection of energy reflected from a target or object by LOS, bistatic, or over-the-horizon radar systems. RADINT collection provides information on radar cross-sections, tracking, precise spatial measurements of components, motion and radar reflectance, and absorption characteristics for dynamic targets and objectives.

Radar MASINT can be active, with the MASINT platform both transmitting and receiving. In multistatic applications, there is physical separation among two or more receivers and transmitters. MASINT can also passively receive signals reflected from an enemy beam.

As with many intelligence disciplines, it can be a challenge to integrate the technologies into the active services, so they can be used by warfighters. Still, radar has characteristics especially appropriate for MASINT. While there are radars (ISAR) that can produce images, radar pictures are generally not as sharp as those taken by optical sensors, but radar is largely independent of day or night, cloud or sun. Radar can penantrate many materials, such as wooden buildings. Improving the resolution of an imaging radar requires that the antenna size is many times that of the radar wavelength. Wavelength is inversely proportional to frequency, so increasing the radar frequency can improve resolution. It can be difficult to generate high power at the higher frequencies, or problems such as attenuation by water in the atmosphere limit performance. In general, for a fixed sensor, electro-optical sensors, in UV, visual, or infrared spectra, will outperform imaging radar.

SAR and ISAR are means of combining multiple radar samples, taken over time, to create the effect of a much larger antenna, far larger than would physically be possible, for a given radar frequency. As SAR and ISAR develop better resolution, there can be an argument if they still are MASINT sensors, or if they create images sufficiently sharp that they properlyare IMINT sensors. Radar can also merge with other sensors to give even more information, such as #Moving Target Indicator. Radar generally must acquire its images from an angle, which often means that it can look into the sides of buildings, producing a movie-like record over time, and being able to form three-dimensional views over time.