Supporting your mission.  No matter where you are.





The FOPEN SAR is an ultrawide-band (UWB) system that uses low frequencies to achieve foliage penetration. The system has a very high frequency (VHF) frequency range of approximately 20-70 MHz and ultra high frequency (UHF) range of approximately 200-500 MHz. Its basic operating principle involves transmitting of pulsed radio frequency waves and receiving the echoes scattered from targets and the ground surface. The echoes are subjected to

analog preprocessing, digitized, and further digitally processed to produce the final imagery.


The resolution of a radar antenna is dependent on the antenna aperture—the larger the antenna, the better the resolution. A SAR takes advantage of motion of the antenna to achieve an apparent antenna length, or aperture, greater than its actual length. As the antenna moves along a flight path, successive echoes are received from the same target and may be processed to give spatial resolution equivalent to an antenna as long as the distance the antenna moved when receiving the target echoes. Thus, the terminology “synthetic aperture radar” is used to describe the radar system.

Atmospheric conditions such as clouds and rain do not significantly degrade the SAR signal. However, the presence of foliage (trees, brush, grasses) can greatly attenuate the signal. The foliage penetration (FOPEN) SAR is an ultrawide-band system that uses lower frequencies to “see” through the foliage and achieve foliage penetration. Its basic operating principle involves transmitting pulsed radio frequency waves and receiving echoes scattered from targets and the ground surface. The echoes are subjected to analog preprocessing, digitized, and further digitally processed to produce the final imagery.

  • Nearly all weather capability
  • Day or night capability
  • Penetration through the vegetation canopy (to a certain degree)
  • Penetration through the soil (to a certain degree)
  • Minimal atmospheric effects
  • Sensitivity to dielectric properties (liquid vs. frozen water)
  • Sensitivity to structure


The primary advantage of using an airborne-based system is the ability to acquire a large amount of data covering a wide area in a relatively short period of time. To the untrained eye, FOPEN generated maps may look like a bird's-eye view of a city at night; however, these images contain useful intelligence, surveillance and reconnaissance information that reveal concealed objects by penetrating foliage, buildings and some terrain while overcoming camouflage, concealment and deception techniques. 

Concept of Operation

SAR techniques exploit the motion of the radar in orbit to synthesize a typically about 10 km long antenna in the flight direction. While the radar is traveling along its path, it is sweeping the antenna’s footprint across the ground while it is continuously transmitting and receiving radar pulses. Every given point in the “radar swath” is imaged many times by the moving radar platform under constantly changing yet predictable observation geometries. In SAR systems, this change in observation geometry, resulting in a constant change of the distance from the radar to the point on the ground, is precisely encoded in the phase of the observed radar response. The “phase history” for any point on the ground located at a constant distance parallel to the flight track is the same. By compensating the phase history of each pulse that is affecting a particular point on the ground, it is possible to focus the energy across the 10 km synthetic aperture and create an image of vastly improved resolution. 

Evolution & History

    FOPEN has been in the field since the late-90s and is the result of a joint Defense Advanced Research Project Agency, U.S. Air Force and Army Advanced Technology Development program. FOPEN was originally used to demonstrate low frequency radar's ability to penetrate, but its proven success allowed it to be used for a variety of mission

Our Involvement

  • Airborne and ground station operations
  • Perform on-site maintenance actions
  • Manage depot support service & RMA
  • Serve as a conduit between the US government beneficiaries


Use Case

Intelligence Gathering

Military Surveillance

Reconnaissance Missions

Disaster Preparation & Response

Counter Drug Trafficking

Search & Rescue Operations

Wildland Fire Monitoring

Pipeline Monitoring

Livestock & Wildlife Monitoring

Counter Illegal Fishing

Monitoring Construction Sites

Monitoring Mining Operations

Infrastructure Monitoring

Border Security

Wildland Fire Studies



  • Identification of targets under concealment
  • National Security initiatives supported
  • Satisfied End Users

Additional Information

For business development inquiries please complete the below form.

Thank you for contacting us. We will get back to you as soon as possible
Oops. An error occurred.
Click here to try again.