As the personal computer shrinks to fit the size of your wrist, modern defense systems are following a similar trend. Military systems are getting smaller and smaller – think UAVs or nanosats – and going multifunctional.
This means one job can no longer be sacrificed for another – a system can no longer deliver just communications, or just signals intelligence. On smaller platforms, condensing multiple functions into one small, powerful package – like condensing a laptop computer to fit on your wrist – is key.
For radio frequency (RF) solutions, digital phased arrays (DPAs) have long been seen as the method to achieve that multifunction. And it is the key reason that they have long been seen as ‘the future’ of Department of Defense (DoD) RF systems. Think of a DPA as a collective of individual antennas, each controlled by a computer, which form radio waves into a variety of beams. Users can digitally define these beams to scan the battlespace in order to surveil, inform, and protect. In contrast to legacy RF systems, a DPA can simultaneously define multiple beams, at multiple frequency bands, to digitally steer each of them in different directions for unprecedented agility and responsiveness.
“As opposed to single, static solutions, digital phased arrays are software-defined, meaning they can be easily and quickly changed to address evolving circumstances – even in the midst of a mission,” said John Knag, technology development director for BAE Systems’ FAST LabsTM research and development organization. “That adaptability is essential in maintaining pace with the ever-evolving electromagnetic spectrum.”
So, why have digital phased arrays been considered ‘the future’ and not ‘the now’? The main factors that held them back in the past are some of their greatest draws today – namely size, weight, power and cost (or simply, SWaP-C). Thanks to strong investments and research developments over the past decade, these barriers have been reduced considerably. Commercial adoption of phased array architectures (5G networks), government investments in semiconductor technology, progress in manufacturing and machining techniques, and the development of faster analog-to-digital converters have all helped to rapidly close this gap.
As past constraints dissolve, DPAs are becoming the standard in RF systems. However, the constant challenge is to further improve functionality without sacrificing SWaP-C. To meet that challenge, BAE Systems’ FAST Labs organization continues to innovate modular solutions that are scalable, reconfigurable, and adaptable. Our plug-and-play modules can be scaled up or down, from nanosat missions, to large fixed-wing aircraft applications, to ground-based needs. They also streamline design and production – to get them into the hands of the warfighter sooner.
The FAST Labs team has been on the forefront of multifunction solutions for years, building from the chip level with MATRICs, a wideband multichannel transceiver in a low SWaP-C package, to a full RF system-in-a-box with CHIMERA™, which leverages the latest advancements in reconfigurable RF components.
Our latest DPAs include a new array-specific MATRICs transceiver chip, which leverages an advanced 130nm SiGe BiCMOS process to further reduce SwaP-C. We’re now building a next-generation software-defined radio to leverage this new chip and deliver unprecedented array performance. These smaller, even more powerful systems will enable higher DPA functionality with less power consumption than ever before.
A few priorities distinguish our approach to digital phased arrays:
One step for higher performance. Better performance is our top priority. So in our DPAs, we process radio signals in analog form first, before digitizing them. Though this traditional technique includes one more step in radio signal conversion than the recent “direct digital” approach, that extra step often yields higher sensitivity, digital control, and dynamic range, which can make the difference in any mission.
Behind the aperture. What’s behind the antennas in DPAs can determine just how “adaptable” these arrays really are. We opt for digitally controlled elements behind each antenna, as they are inherently reconfigurable, and have the ability to transmit and receive in simultaneous modes, with multiple beams at various frequencies. A real-time re-program of one of these digital elements can shift the direction and function of a beam in mere microseconds.
Optimizing for new applications. We’re leveraging common array architectures to enable our DPAs to meet future needs. We demonstrated such capabilities for a rotary wing application in the OASIS program, which aims to integrate our digital phased array technology onto future Army aircraft – one of the most demanding SWaP-C platforms in the DoD’s fleet. Multifunctionality at this level would mean a paradigm shift for use of rotary wing aircraft in the electromagnetic battlespace, equipping more aircraft with organic capabilities previously only possible at the brigade level or higher.
With these priorities in mind, we’re positioned to make our DPAs not only today’s standard, but the core of any future mission. With our dedication to scalable, digitally-defined systems, our low SWaP-C packages will pack a punch and bring unprecedented advantage to any battlespace.