The radio frequency (RF) spectrum is a scarce resource that is becoming increasingly congested and contested as demand for spectrum access continues to grow. Within this crowded environment, the Department of Defense’s RF systems are hampered by mission-compromising interference from both self- and externally-generated signals. Wideband software-defined radio (SDR) systems provide unprecedented access to the RF spectrum and are beginning to proliferate throughout the DoD and commercial applications as a result. Unfortunately, as bandwidth increases, dynamic range tends to decrease, which impacts the radio’s sensitivity and performance.
To mitigate this challenge and support the continued use of these wideband radios, DARPA developed the Wideband Adaptive RF Protection (WARP) program. WARP is exploring the development of tunable filters to manage external interference as well as tunable signal canceller architectures to address self-interference. The goal is to develop technologies that are tunable over wide bandwidths with low-loss and high-linearity that can protect defense and commercial wideband systems.
Today, DARPA announced the research teams selected to tackle WARP’s R&D objectives. These teams will explore a diverse set of technology approaches that include intrinsically-switched electromagnetic (EM) resonators, multiferroics, acoustics, and photonics, which will all come together with new circuit architectures, heterogeneous device integration, and advanced RF packaging. The technical approaches will also include embedded sensing of the EM spectrum, which provides adaptive control of the tuning elements and enables the hardware to react to environmental changes.
“The performers on WARP are exploring a range of novel approaches to develop new circuit architectures for tunable filters and cancellers,” said DARPA program manager, Timothy Hancock. “It is expected that the adaptive filter technology will help protect wideband digital receivers from signal saturation in congested environments and the adaptive cancellers will enable same-frequency simultaneous transmit and receive (STAR) applications over much wider bandwidths than can be achieved today.”
WARP is divided into two primary research areas. The first focuses on the development of new filter architectures that have inherently wideband tuning characteristics to cover the 2-18 GHz band of interest. The research teams selected to take on this area include the University of Pennsylvania; BAE Systems; Raytheon Technologies; Northrop Grumman Corporation; Collins Aerospace, a unit of Raytheon Technologies Corp.; and Indiana Microelectronics.
The second research area is focusing on reconfigurable signal cancellers in the 0.1-6 GHz band of interest while supporting large time delay spreads to handle dispersive signal leakage paths. The research teams working under this area include BAE Systems, L3Harris Technologies, Columbia University, and the University of Pennsylvania.