An RQ-4 Global Hawk Block 20 aircraft hangs inside the
Benefield Anechoic Facility at Edwards AFB 6/30/08
Photo: USAF / Jet Fabara
7/14/2008 - EDWARDS AIR FORCE BASE, CA -- The Global Vigilance
Combined Test Force concluded an electromagnetic profile study
for the Global Hawk Block 20 at the Benefield Anechoic Facility
here July 3.
The three-week study marked the first time the test force used
an entire Global Hawk aircraft for testing inside the anechoic
"With this testing, we want to identify the electromagnetic
profile of the Global Hawk, see if there are any electromagnetic
incompatibility issues and verify that the aircraft is electromagnetically
compatible with itself," said John Hafer, Northrop Grumman
The anechoic facility provided a unique and controlled environment
for this testing, said 2nd Lt. Christopher Stilson, 772nd Test
Squadron project lead engineer.
"We are testing the aircraft at the BAF because we have
a sealed chamber, which allows no radio frequency to come into
or go out of it," Lieutenant Stilson said. "We are
completely sealed off from the outside world and interferences,
such as cell phones and radios, which sometimes make it hard
to separate the aircraft's radio frequency from the environment."
In the past, the combined test force performed testing inside
the chamber with only parts of the Global Hawk, including a
"Now, we have the whole aircraft," said Thomas Stiles,
452nd Flight Test Squadron global vigilance project manager.
"We are trying to get the profile configuration of all
the aircraft, and the only way to do that is to get the complete
The team performed antenna coupling, radiated emission tests
and transient emission tests.
"We turned on the electronic equipment inside the aircraft,
applied power and made sure everything was up and running the
way it normally operates," Mr. Hafer said. "Antennas
were placed around the aircraft to record and measure all the
emissions being generated by the aircraft."
Another set of antennas was also placed around the aircraft
to generate electromagnetic fields at high amplitude.
"We were trying to hit the aircraft with as much power
as possible and make sure that none of the aircraft systems
was affected by that power," Lieutenant Stilson said.
Antenna coupling testing determines how well the antenna isolates
its signal from other radiated signals. With transient emission
testing, the testers looked at the effects of the interference
of the aircraft's power lines.
The result of this testing is part of the Federal Aviation
Administration requirement for the Global Hawk's airworthiness
"It is a certificate required by the FAA to allow an air
vehicle to fly in the national airspace," said Ed De Reyes,
Northrop Grumman EMI Test Lead. "Because the Global Hawk
is an unmanned aerial vehicle, the FAA is requiring a higher
standard for the aircraft."
A great amount of preparatory work was performed for this testing.
Organizations involved included the 452nd FLTS and the 772nd
TS from Edwards; Northrop Grumman; and the Global Vigilance
CTF and the 303rd Aeronautical Systems Group from Wright-Patterson
Air Force Base, Ohio.
"We have been working on this project for about a year,"
Mr. Stiles said. "This is a collaborative effort. During
the entire time, people were going above and beyond to complete
this testing. We couldn't have done it without teamwork."
Source: USAF Edwards AFB Press Release by Senior Airman
Julius Delos Reyes