DARPA researchers eye standard building blocks for RF phased array antennas to speed development, lower costs
ARLINGTON, Va., 13 April 2014. U.S. military researchers plan to spend more than $100 million, involve at least seven defense companies, and award at least nine separate contracts in a landmark project to speed development of electronic RF transmit and receive arrays for communications, signals intelligence (SIGINT), radar, and electronic warfare (EW).
The program, sponsored by the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., is called Arrays at Commercial Timescales (ACT) program, which seeks to move beyond the traditional specialized and time-consuming array design process and focus on new ways of developing RF phased array antennas.
The companies involved in the DARPA ACT program read like a who's who of the nation's most prominent prime defense integrators and top-drawer research institutions. The names include Raytheon, Northrop Grumman, Lockheed Martin, Boeing, Rockwell Collins, HRL Laboratories, and Georgia Tech Applied Research.
Together these organizations are trying to do nothing less than re-invent how the military develops RF and microwave technology for a broad variety of applications that include advanced radar, electronic warfare, communications, and electronic intelligence.
RF phased arrays use numerous small antennas to steer RF beams without mechanical movement. Their lack of moving parts enable them to look in several directions at once, yet this technology is extremely expensive and can take many years to engineer and build.
The problem is the need to start engineering RF arrays from scratch. The DARPA Arrays at Commercial Timescales (ACT) program aims at creating shared hardware for future military phased arrays. ACT technologies could save the Pentagon billions of dollars and require years less research and development time for new systems.
The program has three thrusts: a common building block for RF arrays; a reconfigurable electromagnetic interface; and over-the-air coherent array aggregation.
DARPA awarded the first ACT contracts late last year. The Raytheon Co. Space and Airborne Systems segment in El Segundo, Calif., won a $19.5 million ACT contract on 17 Dec. 2013. The Northrop Grumman Electronic Systems segment in Linthicum Heights, Md., followed the next day with a $21.9 million ACT contract, and the Lockheed Martin Corp. Mission Systems and Training segment in Moorestown, N.J., won an $18.5 million ACT contract on 19 Dec. 2013.
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The new year brought another participant to the ACT program. on 14 Jan. 2014 Rockwell Collins in Cedar Rapids, Iowa, won an $11.5 million contract, followed by a $5.9 million ACT contract to the Raytheon Integrated Defense Systems segment in Tewksbury, Mass., on 26 Feb.
Four more DARPA ACT contracts came last month, beginning on 24 March with a $7.4 million contract to HRL Laboratories LLC in Malibu, Calif.; a $4.6 million contract to the Boeing Co. in Seattle on 26 March; a $5.5 million contract to Georgia Tech Applied Research Corp. in Atlanta on 27 March; and a $5.5 million to Raytheon Integrated Defense in Tewksbury, Mass., on 28 March. In all, Raytheon scooped up three DARPA ACT research contracts.
Today’s RF and microwave systems increasingly use antenna arrays for multiple beam forming and electronic steering, yet these arrays are expensive and time-consuming to develop and upgrade in the field. While the commercial market has set the pace of how electronic systems evolve, military electronics development lags behind, DARPA researchers say.
A fielded military system based on decade-old electronics, for example, has a small fraction of the capabilities of a system based on modern components, and the performance gap is widening between RF components and digital electronics.
As a result, a system with static RF or analog features cannot capitalize on advancements of the underlying digital electronics. Raytheon engineers will help DARPA define a path toward shorter design cycles and infield updates.
The DARPA ACT contractors will try to 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 by developing new technology for custom arrays that takes advantage of constantly evolving digital components.
Specifically, experts from Raytheon Integrated Defense Systems (IDS) in one contract will concentrate on developing a common hardware module applicable to many different array functions, as well as combining arrays on separate platforms into a larger aperture with precise timing and localization. Rockwell Collins also is working on this first thrust of the DARPA ACT program.
In a second separate contract, Raytheon IDS experts will focus on developing a reconfigurable electromagnetic interface for different polarizations, frequencies, and bandwidths by creating a customizable electromagnetic interface to a common module. Boeing, Georgia Tech, and HRL Laboratories also are working on this second thrust of the DARPA ACT program.
Georgia Tech researchers have proposed a reconfigurable electromagnetic interface (REI) with an integrated reconfigurable ground plane that can be optimized in-situ for frequency, bandwidth, beam pattern, steering, null placement, polarization, and input impedance.
They plan to capitalize on the gain of the array to match the gain of the standard array, but with added ability to reconfigure for different missions, to train to its environment, and to require a lower feed density and lower common module density than a traditional array.
Boeing, meanwhile, has proposed a novel RF phased array antenna (PAA) composed of reconfigurable wideband elements. Boeing researchers will scale the device for configurability within the 2-to-12-GHz frequency range but this technique could be scaled to other frequency bands as well.
The reconfigurable array should be modifiable in the field to support common module changes or emergent mission requirements. Reconfigurable arrays have persistent challenges in four main technological categories: array element performance; low-loss switches; controlling switches without hurting array performance; and fabricating interconnect structures.
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The DARPA ACT program also seeks to combine arrays on separate platforms into a larger aperture with precise timing and localization. The goal is to create electromagnetic interface arrays that can be fielded at a rate to match that of commercially developed electronic components.
For more information contact participants online:
-- Boeing at www.boeing.com;
-- Georgia Tech Applied Research at www.gtarc.gatech.edu;
-- HRL Laboratories at www.hrl.com;
-- Lockheed Martin Corp. Mission Systems and Training at www.lockheedmartin.com/us/mst;
-- Northrop Grumman Electronic Systems at www.northropgrumman.com;
-- Raytheon Space and Airborne Systems at www.raytheon.com/capabilities/ew;
-- Raytheon Integrated Defense Systems at www.raytheon.com/capabilities/c4isr;
-- Rockwell Collins at www.rockwellcollins.com; or
-- DARPA at www.darpa.mil
John Keller | Editor-in-Chief
John Keller is the Editor-in-Chief, Military & Aerospace Electronics Magazine--provides extensive coverage and analysis of enabling electronics and optoelectronic technologies in military, space and commercial aviation applications. John has been a member of the Military & Aerospace Electronics staff since 1989 and chief editor since 1995.
