DARPA Program Aims to Reduce Cost of Electronic Antenna Systems
By Christina Munnell
Electronic antenna systems, which are used on aircraft and other military platforms for radar, communications and electronic warfare, are notoriously costly to both develop, maintain and upgrade.
A Defense Advanced Research Projects Agency program is seeking to sharply reduce the cost and years it takes to develop electronically scanned array antennas (ESA).
“The DoD customer base has been requesting ESAs for years, but it has not previously been affordable,” said Lee Paulsen, a principal electrical engineer at Rockwell Collins, which recently received a $10 million DARPA award to enhance the antenna designs with more versatile, digital versions.
DARPA’s description of the Arrays at Commercial Timescales (ACT) program, said: “It is imperative to define a path toward shorter design cycles and in-field updates and push past the traditional barriers that lead to 10-year array development cycles, 20- to 30-year static life cycles and costly service life extension programs.”
Rockwell Collins will develop a common building block component that makes these antenna systems reconfigurable and readily upgradeable, driving down the cost of procurement by at least 80 percent, according to Paulsen.
Roy Olsson, program manager for the microsystems technology office at DARPA, said, “The goal is to realize as much commonality as possible without degrading performance or significantly increasing power consumption.”
Traditional antenna systems were mechanically steered and were designed to be application-specific. This made it difficult to upgrade the technology and use it across various platforms, Olsson explained. The ACT program, which was established in February of 2013, wants to make ESAs more adaptable by creating a standard design that can be used across multiple platforms.
Along with increased adaptability, an improved ESA system could help speed up the beam-forming process, allowing pilots to detect radar threats more quickly and make them less vulnerable to electronic warfare. Because mechanically steered systems must be physically guided, it often takes a fair amount of time to orient and aim the antennas in different directions, said Paulsen.
“In an ESA, you simply set the control signals and, regardless of where the antenna was previously pointed, the beam will form in the new direction. [This] allows us to move the antenna gain pattern around in space much faster than could ever be done with motors,” he said.
Sharp, reliable signaling is important for effective communication and information sharing among different services as well. Typical radio frequency systems, like cellular phone systems, separate different RF signals based on time and frequency, allowing for many simultaneous users along the spectrum, Olsson explained. But ESAs add an important third dimension in distinguishing RF signals: space.
“With an increasingly crowded RF spectrum contested by multiple jamming sources, being able to separate signals in space and to choose the source of RF energy to be received is important,” Olsson said.
When ESAs transmit these RF signals, they allow the radiation to be targeted in one specific direction and to be pointed at an intended recipient, Olsson said. This reduces the required transmit power compared to a traditional antenna, which radiates in all directions.
An ESA’s ability to target its beams, and electronically steer both the received and the transmitted RF beams, will make military communications much more difficult to jam and to intercept, Olsson added.
While the antennas can quickly form beams and move them around in space, they can also form a “null” — a direction in space where the array is not receiving any energy. This reduces the chance of radar interference, Paulsen explained. “You can imagine how that would come in handy when trying to counter an adversary that is blasting RF energy at you to try and jam your radar.”
Although ESAs replaced mechanically steered antennas in the most critical defense applications long ago, the high cost and duration of their development continues to prevent their widespread adoption for military forces, Olsson said.
The ACT program will attempt to cut these costs by modernizing older systems and compressing the time it takes to design new ones, Olsson explained.
Analog components are more difficult to transition to advanced technologies because they are generally hand-designed and obsolete. But recent improvements in the type of data converters used to exchange information between analog and digital domains can modify these old systems to keep communication technology up to date for the services, Olsson said.
Rockwell Collins will use DARPA’s $10 million contract to demonstrate enhanced ESA capabilities in about three years, according to Paulsen. The company intends to sell the resulting technology to both commercial and defense customers.