Size, Weight and Power Constraints

Most people are familiar with the concept of RADAR. Radio frequency (RF) waves travel through the atmosphere, reflect off of a target, and return to the RADAR system to be processed. The amount of time it takes to return correlates to the object’s distance. In recent decades, this technology has been revolutionized by electronically scanned (phased) arrays (ESAs), which transmit the RF waves in a particular direction without mechanical movement. Each emitter varies its phase and amplitude to form a RADAR beam in a particular direction through constructive and destructive interference with other emitters.

Phased radio frequency (RF) arrays use numerous small antennas to steer RF beams without mechanical movement (think radar without a spinning dish). These electronics are invaluable for critical DoD applications such as radar, communications and electronic warfare. Their lack of moving parts reduces maintenance requirements and their advanced electromagnetic capabilities, such as the ability to look in multiple directions at once, are extremely useful in the field. These benefits, though, come with a high price tag. Current phased arrays are extremely expensive and can take many years to engineer and build.

Two teams of DARPA performers have achieved world record power output levels using silicon-based technologies for millimeter-wave power amplifiers. RF power amplifiers are used in communications and sensor systems to boost power levels for reliable transmission of signals over the distance required by the given application. These breakthroughs were achieved under the Efficient Linearized All-Silicon Transmitter ICs (ELASTx) program. Further integration efforts may unlock applications in low-cost satellite communications and millimeter-wave sensing.

DARPA’s Adaptable Sensor System (ADAPT) program aims to transform how unattended sensors are developed for the military by using an original design manufacturer (ODM) process similar to that of the commercial smartphone industry. The goal is to develop low-cost, rapidly updatable intelligence, surveillance and reconnaissance (ISR) sensors in less than a year, a marked improvement to the current three-to-eight year development process.

The submillimeter wave, or terahertz, part of the electromagnetic spectrum falls between the frequencies of 0.3 and 3 terahertz, between microwaves and infrared light. Historically, device physics has prevented traditional solid state electronics (microchips) from operating at the terahertz scale. Unlocking this band’s potential may benefit military applications such as high data rate communications, improved radar and unique methods of spectroscopy—imaging techniques that provide better tools for scientific research. However, access to these applications is limited due to physics.