DARPA’s ACT & ACT-IV developed software defined RF phased array antennas that perfrom communications, radar, and electronic warfare (EW) simultaneously

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Introduction: Reinventing the Radar—Why Phased Arrays Needed a Revolution

Phased arrays—electronically steered antenna systems with no moving parts—are at the heart of modern defense, enabling radar, electronic warfare (EW), and communications simultaneously across platforms from fighter jets to naval destroyers.  Unlike mechanically rotated dishes, these arrays steer their beams by adjusting the phase difference between radiated signals from individual elements, allowing them to redirect energy with speed, precision, and no moving parts. This principle of phase-dependent superposition enables in-phase signals to combine constructively, enhancing signal strength, while counter-phase signals cancel each other out—offering dynamic beamforming capabilities crucial for real-time battlefield operations.

These electronically steerable arrays now underpin critical Department of Defense (DoD) functions such as radar surveillance, secure communications, and electronic warfare. Their ability to form multiple beams simultaneously, scan vast areas within milliseconds, and maintain high-power performance with reduced maintenance has made them a cornerstone of 21st-century combat systems. Whether tracking hypersonic threats, jamming adversarial radar, or facilitating resilient satellite uplinks, phased arrays are prized for their multi-functionality, range, and agility in complex electromagnetic environments.

Yet these advantages have come at a steep cost. Traditional phased array development often exceeds $10–30 billion per program, with 10+ year timelines—in large part due to bespoke engineering requirements. Arrays must be customized for every new platform, whether a naval destroyer or airborne EW pod, with each implementation requiring its own signal architecture, hardware layout, and power optimization. This siloed, “brick-by-brick” approach has not only stifled scalability and upgradability but also hindered cross-platform integration and rapid technological refresh.

These “brick” architectures use rigid ceramic modules assembled semi-manually, resulting in siloed functionality (radar in one, EW in another) that is almost impossible to upgrade post-deployment. Meanwhile, commercial telecommunications arrays are advancing with AI-driven beam agility, putting military systems at risk of falling behind.

As commercial sectors, particularly telecom and 5G, accelerate ahead with agile, software-defined antenna arrays, the U.S. military risks losing its edge in the electromagnetic domain. Consumer-grade systems are now achieving beamforming and reconfiguration capabilities once reserved for cutting-edge defense platforms—raising the alarming possibility of technological parity with peer adversaries, or worse, overmatch in electromagnetic maneuver warfare. In this context, shrinking development cycles and enabling field-upgradable, multi-mission arrays is not merely a cost-saving endeavor—it’s a strategic imperative.

To address this challenge, DARPA launched the Arrays at Commercial Timescales (ACT) initiative in 2013, later scaling into a multiyear, $100+ million program involving top defense contractors, semiconductor firms, and university research labs. Its goal: to reimagine phased array development using modular digital building blocks, software-defined RF interfaces, and distributed coherence across platforms, thereby collapsing timelines from years to months and costs from billions to millions—without sacrificing performance. The result is a seismic shift from legacy radar silos to adaptable, plug-and-play electromagnetic systems ready for the battlespace of tomorrow.

DARPA’s ACT Program: A Three-Pronged Strategy for Disruption

Launched in 2013, DARPA’s Arrays at Commercial Timescales (ACT) program set out to revolutionize how the U.S. Department of Defense builds and deploys phased array systems. Traditional phased arrays—critical for radar, communications, and electronic warfare—have long suffered from extremely high costs, lengthy development cycles, and siloed functionality.

The ACT program tackles these issues head-on by developing modular, software-defined arrays that can be adapted across missions, platforms, and domains with significantly reduced timelines and costs. To overcome the steep costs and sluggish timelines of traditional phased array development, DARPA launched the Arrays at Commercial Timescales (ACT) program. Rather than committing to massive, inflexible hardware systems, ACT envisions a modular architecture: digitally interconnected building blocks that can be rapidly configured and deployed across platforms and mission types.

At its core, ACT pursues three transformative thrusts: standardized digital building blocks, reconfigurable electromagnetic interfaces, and distributed array synchronization.

1. Common Digital Building Blocks: The “Lego” Approach to Arrays

To break free from the inefficiencies of bespoke hardware, ACT introduced digitally-influenced common modules—the foundation of its “Lego-style” design philosophy. Developed by Raytheon and Georgia Tech, these reusable tiles consolidate 80–90% of core functions such as beamforming, signal processing, and amplification into compact modules.

Developed in collaboration with Raytheon, Georgia Tech, and MACOM, these modules combine GaN amplifiers, RF transceivers, phase shifters, and control logic into compact, surface-mountable tiles. Designed for reuse across radar, communications, and EW systems, they reduce non-recurring engineering costs—typically 30–40% of total program budgets—while enabling faster iteration, field-upgradability, and cost-effective mass production.

MACOM’s SPAR™ Tiles exemplify this approach, using surface-mount technology (SMT) to integrate antenna elements, GaN/GaAs transceivers, and power distribution into low-cost, scalable units. Unlike traditional “brick” architectures that rely on complex manual assembly, SPAR tiles can be manufactured using automated assembly lines, slashing production times by over 70%. This modularity is key to accelerating the deployment of new systems while reducing program budgets by billions.

2. Reconfigurable Electromagnetic Interfaces (REI): A Single Aperture for Every Mission

Traditional arrays are often locked into a single role—be it radar, EW, or communications—because of fixed electromagnetic characteristics. DARPA’s ACT program disrupts this by developing Reconfigurable Electromagnetic Interfaces (REI) that dynamically adapt to mission requirements. Boeing, for instance, has pioneered frequency-agile elements covering the 2–12 GHz range. These use tunable metamaterials to modulate bandwidth, polarization, and beam direction on the fly, making it possible to perform electronic surveillance, jamming, and secure communication through a single aperture.

In parallel, Georgia Tech has developed integrated ground planes that support real-time optimization across domains. These innovations eliminate the need to swap hardware for different roles and enable true multifunctionality—critical for joint operations where platforms must quickly pivot between intelligence gathering, threat suppression, and secure data transmission. By decoupling the RF front end from rigid hardware, REI technologies bring unparalleled agility to the electromagnetic battlespace.

Table: ACT’s Technical Thrusts vs. Traditional Array Limitations

3. Over-the-Air Coherent Aggregation: Creating a Virtual Aperture Across Platforms

The final thrust of ACT focuses on coherent aggregation—the ability to synchronize multiple array elements across physically separate platforms, such as ships, drones, and aircraft. Raytheon’s RAPID system enables this by leveraging quantum-resistant datalinks to coordinate distributed sensors in real time. These synchronized arrays function as a unified “virtual aperture,” vastly increasing effective range, resolution, and signal strength.

Supporting this system is DARPA’s PREW (Precise Reference and Engagement Waveform) project, which provides sub-nanosecond synchronization accuracy—a critical requirement for coherent jamming, radar fusion, and long-range threat engagement. This capability opens the door for integrated electromagnetic operations across joint forces, transforming a loosely connected set of sensors into a coordinated, software-defined electromagnetic weapon system. By moving beyond platform-centric arrays to distributed, interoperable systems, ACT is laying the groundwork for scalable, battlefield-wide sensing and engagement.

Breakthrough Implementations: From Weather Radar to Battlefield EW

DARPA’s ACT program is no longer just a concept—it’s producing tangible, transformative implementations across both civil and military domains. One of the clearest examples of this is the Multi-Function Phased Array Radar (MPAR), a joint initiative with NOAA and the FAA that showcases the seamless integration of defense-grade technology into public infrastructure. Powered by MACOM’s SPAR tiles, MPAR replaces over 550 legacy radars—including those used for weather surveillance and air traffic control—with a unified, dual-polarized S-band array. Each of the 86 panels leverages GaN-based 8W transmitters, capable of emitting simultaneous horizontal and vertical beams. This enables unprecedented capability: MPAR can track aircraft while also identifying storm structures, precipitation types, and even biological hazards like birds or insects—critical data for both aviation safety and meteorological forecasting. The result is a robust, multifunctional system that reduces redundancy, operational costs, and infrastructure complexity.

The ACT-IV system, developed by Northrop Grumman and delivered to AFRL/DARPA in 2021, represents a leap forward in battlefield array technology. As the first fully digital active electronically scanned array (AESA) built on ACT principles, ACT-IV breaks down the traditional compartmentalization of radar, communications, and electronic warfare systems. Its independent transmit/receive channels allow for real-time reprogramming of waveforms, enabling the array to jam enemy radars, maintain encrypted comms, and run adaptive radar modes—all simultaneously. For instance, in an electronic attack scenario, ACT-IV can direct destructive interference at an adversary’s radar while preserving friendly communications by dynamically reconfiguring beam nulls. This flexibility allows warfighters to respond to jamming or spoofing threats within microseconds, a feat previously unimaginable with fixed-function systems. Additionally, ACT-IV is linked to a “community cloud” hosted by AFRL, allowing researchers to upload and test new algorithms, accelerating innovation through digital twin environments.

To ensure the widespread adoption of modular array systems, DARPA launched the Puck Initiative in 2019. This initiative addresses one of the remaining obstacles in phased array evolution: the lack of a standardized interface between reconfigurable RF frontends and digital backends. Traditional systems often required fully customized apertures for each mission, creating logistical bottlenecks and long upgrade cycles. The Puck framework proposes a universal RF interface, enabling operators to swap “personalities” of a sensor via software, much like changing camera lenses for specific photography needs. Whether the array is required for high-power jamming, long-range tracking, or low-probability-of-intercept comms, Puck makes it possible to deploy the same hardware with new software-defined capabilities. This dramatically reduces lifecycle costs, enhances mission adaptability, and supports the rapid fielding of upgrades as threats evolve.

DARPA’s ACT-IV PUCK RFI: Standardizing the Future of RF Modularity

In October 2019, the Defense Advanced Research Projects Agency (DARPA) took a critical step toward redefining phased array architecture by issuing a Request for Information (RFI) on the ACT-IV PUCK Aperture. This RFI, released by DARPA’s Microsystems Technology Office (MTO), sought insights into design and fabrication practices for phased array apertures that could dramatically lower Non-Recurring Engineering (NRE) costs. The initiative aimed to overcome one of the biggest bottlenecks in RF systems development: the expensive, time-consuming need to design customized front-end hardware for each new mission-specific application.

DARPA’s RFI was not simply an exploratory gesture—it was part of a broader strategy to support the next generation of electromagnetic systems that are reconfigurable, programmable, and software-defined. As defense applications increasingly converge—combining radar, communications, signal intelligence (SIGINT/ELINT), and electronic warfare (EW) into multi-functional arrays—the need for a standardized RF “personality layer” has become essential. These arrays, operating across wide frequency bands and supporting numerous independent transmit/receive (Tx/Rx) channels, demand an architecture that can evolve as rapidly as the software behind them.

At the core of this evolution lies the separation of RF frontends from digital backends, often referred to as Digital Receiver/Exciters (DREX). While DREX systems are highly reconfigurable and reusable, they rely on front-end aperture systems tailored to specific missions. These “RF personalities” must include specialized amplifiers, filters, analog subarrays, and other components that optimize performance for power output, signal clarity, and spectral agility. Unfortunately, the process of building these custom apertures is expensive and time-intensive, undercutting the flexibility that DREX promises.

DARPA’s PUCK initiative, a foundational element of the ACT-IV (Arrays at Commercial Timescales – Integration and Validation) program, directly tackles this challenge. By standardizing the interface between the digital backend and the RF front end, PUCK aims to create modular, swappable aperture systems that can plug into any mission profile. Much like switching lenses on a camera body, PUCK’s goal is to enable array systems that can be reconfigured for drastically different applications—without starting from scratch. This architectural shift is expected to not only reduce program costs, but also vastly accelerate fielding timelines, ensuring that U.S. defense systems stay ahead of adversaries in the electromagnetic spectrum (EMS) domain.

Ultimately, the PUCK RFI represents a significant inflection point in phased array evolution. It marks DARPA’s recognition that maintaining technological superiority requires commercial-speed modularity, not just in software, but in hardware as well. With ACT-IV and PUCK working in tandem, the Department of Defense is laying the groundwork for truly agile, multi-mission, and upgradeable EMS systems capable of dominating future electronic battlespaces.

Together, these implementations—MPAR, ACT-IV, and the Puck Initiative—demonstrate the full-spectrum impact of ACT’s modular architecture. They bring the promise of universal array systems closer to reality, blending military-grade performance with the responsiveness and scalability of commercial electronics development. By enabling one sensor suite to fulfill multiple roles, ACT is redefining not just how phased arrays are built, but how electromagnetic warfare and sensing are conducted in the 21st century.

Industry Momentum: Commercial Tech Accelerating Defense Agility

DARPA’s Arrays at Commercial Timescales (ACT) program has catalyzed a groundbreaking collaboration across the U.S. defense and research ecosystem. Leading companies awarded ACT contracts include Raytheon, Northrop Grumman, Lockheed Martin, Boeing, Rockwell Collins, HRL Laboratories, and Georgia Tech Applied Research Corporation. Each partner brings unique technological capabilities to address the core pillars of ACT: modular digital building blocks, reconfigurable electromagnetic interfaces, and distributed phased array aggregation.

Raytheon Integrated Defense Systems (IDS) has been tasked with developing a common hardware module capable of supporting a wide range of phased array functions. Leveraging its RAPID (Rapid Array Performance Improvement and Deployment) architecture, Raytheon is building scalable, digitally-driven building blocks that reduce both cost and deployment time. According to Paul Ferraro, Vice President of Advanced Technology Programs at Raytheon IDS, “Raytheon shares DARPA’s vision of a common digital beamforming architecture platform to enhance affordability and upgradability.” Their efforts not only aim to compress development timelines but also to ensure that arrays can be updated in the field with minimal hardware changes—essential in countering fast-evolving threats.

At Georgia Tech, researchers have advanced the concept of a Reconfigurable Electromagnetic Interface (REI) featuring an adaptive ground plane that dynamically adjusts for mission-specific needs. Their design can optimize variables like bandwidth, polarization, input impedance, and beam steering in real-time. This approach allows phased arrays to intelligently train themselves to their operating environment while reducing the need for dense feed networks. Georgia Tech’s REI concept enhances the flexibility and efficiency of ACT arrays, allowing a single system to replace many static, purpose-built architectures.

Boeing is contributing an innovative reconfigurable RF phased array antenna (PAA) composed of wideband, tunable elements designed to operate across the 2–12 GHz spectrum. Their field-modifiable design supports on-the-fly configuration to meet emergent mission requirements or integrate with evolving digital backend systems. Boeing’s solution tackles persistent challenges in array element performance, low-loss RF switching, control signal isolation, and robust interconnect design—all while prioritizing in-theater adaptability for future battlefields.

The defense sector is increasingly turning to commercial technology for breakthroughs in speed, scalability, and performance. A landmark example is the strategic partnership between MACOM and Northrop Grumman, which signals a major shift in how defense-grade phased arrays are developed and produced. MACOM now exclusively supplies planar SPAR™ tiles for Northrop’s advanced radar systems. These tiles are manufactured using automated surface-mount technology (SMT)—a production method long standard in commercial electronics. This shift from labor-intensive “brick” arrays to automated tile-based architectures enables a fivefold reduction in manufacturing costs, making next-gen radar and EW systems not only faster to produce but also economically viable for broader deployment across multiple platforms.

SPAR Tiles form the building blocks of the Multi-Function Phased Array Radar (MPAR) system, a dual-polarization, AESA-based radar platform that merges civil and military capabilities. Notably, the MPAR program aims to consolidate 350 aircraft tracking radars and 200 weather radars into 365 unified systems, potentially saving the U.S. taxpayer $4.8 billion in operating costs. By fusing air traffic control and meteorological data into a single, networked infrastructure, the system enhances situational awareness across both defense and civilian sectors.

Another driving force behind this momentum is Analog Devices, whose RF electronic solutions are redefining what’s possible in beamforming. Their heterodyne and direct-sampling integrated circuits (ICs) allow for hybrid analog/digital beamforming, creating systems that are both agile and low in size, weight, and power (SWaP). These ICs support multi-beam, multi-function operations in a single array, enabling applications such as simultaneous surveillance, tracking, and jamming—all in real time. This is critical for modern conflict zones, where sensors must rapidly switch roles or manage overlapping tasks without hardware swaps. By reducing form factor while increasing functionality, Analog Devices is helping push the envelope of SWaP-optimized multi-mission systems.

Complementing this evolution is the ongoing GaN (gallium nitride) revolution, supercharged by MACOM’s acquisition of Wolfspeed’s RF division. GaN technology has long been celebrated for its higher power density, thermal stability, and wide bandwidth, outperforming older GaAs (gallium arsenide) solutions. With control over Wolfspeed’s GaN-on-SiC (silicon carbide) production capabilities, MACOM can now deliver next-gen RF amplifiers that not only boost signal strength but also enhance system survivability in contested electromagnetic environments. These advancements are particularly impactful for hypersonic missile tracking, EW hardening, and high-frequency radar systems that must withstand extreme operational conditions.

Northrop Grumman’s EMRIS: A Direct Offshoot of DARPA’s ACT Vision

Northrop Grumman’s recent successful first flight of the Electronically-Scanned Multifunction Reconfigurable Integrated Sensor (EMRIS) marks a critical milestone in realizing the goals of DARPA’s Arrays at Commercial Timescales (ACT) program. EMRIS is a digitally reconfigurable active electronically scanned array (AESA) capable of performing radar, electronic warfare, and communications functions simultaneously. Unlike legacy radar systems that are static and difficult to upgrade, EMRIS exemplifies ACT’s core philosophy: flexible, upgradable, and software-defined RF systems that evolve at the pace of digital electronics. This adaptability is essential for countering fast-changing threat environments, where waveforms, jamming tactics, and electromagnetic interference evolve rapidly.

Built on the semiconductor innovations made under ACT, EMRIS integrates advances in digital beamforming, low-SWaP chipsets, and reprogrammable RF backends to enable rapid mission reconfiguration without the need for hardware overhauls. This transformation was made possible by Northrop Grumman’s investment in specialized microelectronics fabrication facilities in California and Maryland, where purpose-built defense chips—often in low volume—are digitally modeled, simulated, and manufactured using digital twin technologies. These capabilities drastically reduce design cycle time and ensure that platforms like EMRIS can be rapidly tailored to new operational requirements—aligning perfectly with DARPA’s push toward field-upgradable phased arrays and eliminating the lag between emerging threats and system readiness.

EMRIS’s modular and scalable architecture not only enhances survivability in contested electromagnetic environments but also reflects the broader transition of defense systems away from monolithic platforms toward distributed, interoperable, and software-driven sensor networks. As the ACT program continues to catalyze innovations across radar, EW, and communications, EMRIS stands as a tangible proof of concept—a multi-mission asset that underscores how ACT-enabled digital arrays are transforming military sensing from rigid tools into agile, adaptive capabilities for 21st-century warfare.

Together, these industry moves represent a decisive trend: the blurring line between commercial innovation and military application. Through the infusion of automated manufacturing, miniaturized high-performance electronics, and cutting-edge materials like GaN, defense contractors are building systems at commercial speed—without compromising on lethality or resilience. This synergy ensures that future U.S. defense systems can outpace adversaries in both technology and tempo.

DARPA’s ACT initiative is ushering in a new era of electromagnetic agility—where one array can serve as radar, jammer, and communications node under software control. As breakthroughs like MPAR, ACT-IV, and MACOM’s SPAR radar demonstrate, militaries are moving away from static, task-specific arrays toward flexible, upgradeable systems able to adapt in days rather than decades. With Puck driving standardization across the board, the shift from fixed hardware to digital “app-store” capabilities signals the end of obsolescence and the beginning of a truly agile defense architecture.

Summary: DARPA’s ACT Program—Revolutionizing Phased Arrays for Agile Multi-Mission Defense

The Arrays at Commercial Timescales (ACT) program, launched by DARPA, aims to transform the traditionally expensive, inflexible, and slow-to-deploy radio frequency (RF) phased array systems used in defense applications such as radar, communications, and electronic warfare. Historically, these systems have taken over a decade and billions of dollars to develop, often locking in fixed functionality and resisting upgrades. ACT targets this problem by introducing modular, software-defined phased array architectures that evolve at the speed of commercial electronics.

ACT’s core innovation lies in its three-pronged approach:

1. Common digital building blocks (developed by Raytheon, MACOM, and others) consolidate 80–90% of phased array functions into reusable tiles, dramatically lowering costs and development times.

2. Reconfigurable electromagnetic interfaces (REI) (from Boeing and Georgia Tech) use tunable metamaterials and integrated ground planes to enable arrays to adapt in real-time to changing mission profiles across S-band to X-band.

3. Over-the-air coherent aggregation, via Raytheon’s RAPID system and DARPA’s PREW timing tech, allows arrays on different platforms to act as one unified virtual aperture.

These advances are already being fielded. MACOM’s SPAR™ Tiles power the FAA’s Multi-Function Phased Array Radar (MPAR), replacing 550 radar systems with one multi-role, cost-efficient array. Northrop Grumman’s ACT-IV AESA system runs radar, EW, and comms simultaneously and supports software-defined upgrades. The PUCK initiative, a DARPA-led effort, is standardizing the interface between reconfigurable RF frontends and digital backends to further reduce non-recurring engineering (NRE) costs.

Northrop’s EMRIS sensor, a direct outcome of the ACT program, demonstrates this vision in flight—combining radar, EW, and communication functions in a single AESA that can be digitally reconfigured in the field. Supported by next-gen semiconductor manufacturing and digital twin modeling, EMRIS reflects the ACT philosophy: fast, scalable, and upgradable phased arrays that adapt to new threats without hardware redesigns.

Overall, DARPA’s ACT program is redefining the future of defense sensing systems—shifting from hardware-centric, siloed platforms to interoperable, agile, software-upgradable arrays capable of operating across multiple domains with reduced cost, enhanced speed, and mission flexibility. It signals the end of static arrays and the beginning of dynamic electromagnetic agility for U.S. forces.

Across the fleet and battlefield, modular tiles, dynamic RF control, and distributed coherence are redefining how forces see and shape the electromagnetic spectrum.