Finding targets beneath the leaf canopies of forests and jungles hasn’t been a high priority in Iraq and Afghanistan. However, U.S. military researchers are planning tests of foliage-penetrating lasers and radars for tomorrow’s wars and to uncloak today’s smuggling operations, which often take place in tropical regions.

Top among the organizations interested in the technology is U.S. Southern Command, which directs allies and law enforcement agencies against smugglers of drugs, people and money in the Central and South American jungles.

In the coming weeks, SouthCom’s Innovations Office plans to conduct a field demonstration in Central America using an unmanned A160 helicopter and a sensor called the Foliage Penetration Reconnaissance, Surveillance, Tracking and Engagement Radar (FORESTER). It uses foliage-penetrating radar frequencies to spot moving objects, including people.

“Demonstrations carried out to date have shown its potential for giving us an advantage when monitoring for illicit trafficking activities in areas where detection of such activities has proven extremely challenging in the past,” said Southern Command spokesman Jose Ruiz.

SouthCom is working on FORESTER with the Defense Advanced Research Projects Agency (DARPA) and lead contractor SRC, formerly Syracuse Research Corp.

SRC is not the only company pioneering foliage-penetrating radar. Lockheed Martin started work with DARPA in 1997 on a sensor originally called FOPEN, short for foliage penetration. The sensor, flown operationally on Army C-12 aircraft and to be tested soon on a NASA unmanned plane, has been renamed the Tactical Reconnaissance and Counter-concealment Enabled Radar (TRACER).

Lockheed’s early FOPEN sensor was subjected to two lines of testing from 2003 to 2005. A DARPA and Army program focused on using it for mapping and detecting movement with high-resolution images created using UHF, and an Air Force program looking at its ability to detect missile launchers and tanks with better-penetrating VHF.

In an account that Southern Command did not comment on, Lockheed said that in 2005, the Defense Department decided to send FOPEN to Southern Command to see how the radar system performed in the field.

“They said ‘let’s go take it somewhere and see what it can do flying on a U.S. Army C-12,’” said Robert Robinson, Lockheed’s manager for foliage penetration development.

Within about 10 days, “we began getting operational task missions,” he said.

The operations made it difficult to conduct tests. “It was a struggle between the operational community and the scientific community. It’s a good struggle to have — better than to have nobody wanting it,” Robinson said.

Because of the technology’s success, the Office of the Secretary of Defense approved an upgrade and repackaging of the technology. The new, improved technology was named TRACER. The Army awarded Lockheed a $40 million contract in May 2007 to adapt the instrument for unmanned aircraft.

Flight testing on a NASA Predator B aircraft is scheduled for September, probably at Edwards Air Force Base, Calif., Lockheed said. Next year the company plans to fly it on the Army’s Predator-like craft, the Extended Range Multi-Purpose (ERMP) plane. The Predator B uses the same flight control software as the Army plane, the company said.

“That way, we can mimic the flights speeds and altitudes of the ERMP,” spokeswoman Suzanne Smith said by e-mail.

The unmanned version of TRACER has been whittled down to less than 300 pounds — a 50 percent weight reduction -— and its power consumption cut by two-thirds.

TRACER can peer through three levels of a jungle canopy, Robinson said. Part of the Army’s focus in the development of TRACER has been developing computer algorithms and tweaking software to improve the quality of the imagery, he said.

“As the technology matured, the Army and other end users got smarter on what they wanted,” he said.

Even with the improved imagery, intel analysts have to be trained on techniques for picking up on what the images represent, and that training is specific even to the region of the globe where the imagery is taken, Robinson said. The TRACER images are quite different even from other synthetic aperture radar images, which in the S-band frequency can be “almost photographlike,” Robinson said. “In this frequency domain, it’s not that apparent.”

“The beauty of the system is that it doesn’t necessarily have to go on a UAV. It can go on a manned platform,” Robinson said.

As currently constructed, TRACER can be enclosed in a radome on a manned aircraft, including an antenna and a gimbal that shoots the radar signal at the area of interest on the ground. On an unmanned plane, it is enclosed in four or five boxes or in a single pod. In the manned aircraft setup, an analyst or two can process the data on board during the flight, or the plane can send the information to the ground for processing via a data link.

TRACER and FORESTER are the products of years of basic research. Typical radar signals, such as air traffic control or police radars, cannot penetrate foliage, said Bryan Burns, a senior engineer at Sandia National Laboratories projects who worked on early foliage-penetration technologies in the 1990s. Scientists had to find the right frequencies for the job.

As the frequency of the radar’s electromagnetic waves goes down, its ability to penetrate foliage improves, but its ability to pick up on smaller objects decreases, Burns said. In the UHF band between 300 and 3,000 megahertz, synthetic aperture radar on an airplane can spot building-sized objects beneath foliage, he said.

“The terrain tends to disappear at lower frequencies,” Burns said, as the sand and gravel tend to absorb rather than reflect the radar.

Multipolarization

Another factor that determines the effectiveness of foliage-penetrating radar is the size and shape of the object it is seeking, he said. Foliage-penetrating radars can see man-made objects with sharp angles very well, while smooth-surfaced objects don’t show up well. One way to improve synthetic aperture radar images is through multipolarization, or setting up the radar’s sending and receiving antenna to transmit and receive vertical waves only, or horizontal only, or to transmit vertically and receive horizontal signals, or vice versa, Burns said.

Lasers are another foliage penetration option. General Atomics Aeronautical Systems is working on a project with DARPA and the Air Force to explore the use of reflected laser light to produce three-dimensional targeting maps and also see beneath forest canopy. The main purpose of the project is mapping, but the technology also “does a good job of foliage penetration,” said Robin Snider, director of electro-optical systems for the reconnaissance systems group at General Atomics.

The project — called Standoff Precision ID in 3-D, or SPI-3D — uses short, fast pulses of lasers shot from an airplane to illuminate a target area. The laser pulses, which are undetectable to the naked eye, are as much as 100 meters wide, Snider said. When foliage is involved, light bouncing off the leaves is filtered out, leaving only the picture elements, or pixels, from whatever is below. These are processed into 3-D images

General Atomics is under contract with DARPA to perform a demonstration of the SPI-3D in the pod by September 2011, Snider said.

With SPI-3D, the Air Force’s goal with targeting is to generate images that provide updated, exact geolocation targeting information, Snider said. That ensures that GPS-guided weapons are hitting the correct building, for example, or even the exact corner or floor of that building, and not relying on outdated mapping information. In a suburban neighborhood where buildings look alike, a three-dimensional image matched to the exact targeting coordinates would ensure there is no confusion about which building to hit, or a need to go back to targeting databases that may have old information, Snider said.

So far, the SPI-3D has been flown in manned aircraft. The Air Force’s goal is to have it operate from a self-contained pod that can be attached to the bottom of a manned or unmanned aircraft. Eventually, it might be incorporated into the electro-optical-infrared camera ball carried on a Predator B.

Ben Iannotta contributed to this report.