Draper Lab joins project to design tiny military RF and microwave transmitters, receivers, and antennas

June 4, 2024
Primary challenge is to design RF receivers and transmitters that are much smaller than the wavelength of the radio signals to be sent and received.

ARLINGTON, Va. – RF and microwave experts at the Charles Stark Draper Laboratory Inc. in Cambridge, Mass., are joining a U.S. military research project to develop small RF receivers, transmitters, and antennas for space-constrained RF and microwave applications in sensors and communications.

Officials of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., announced a $4.5 million contract to Draper Lab in May for the Macaroni project to develop tiny RF receivers and transmitters. Details of the project are secret.

Draper Lab joins SRI International in Menlo Park, Calif., and HRL Laboratories LLC in Malibu, Calif., on the Macaroni program. SRI won a $16.8 million contract, and HRL won a $23.2 million contract for the project last April.

DARPA is asking Draper Lab and SRI engineers to develop RF and microwave components that not only should exceed today's state of the art, but also should seek to overcome long-established design limitations of the so-called Chu Limit that constrains the bandwidth of data that can be sent and received from small antennas.

Related: Types of Antennas at the RF and Microwave Frequency

Measurement and control of the electromagnetic spectrum is a key research area the U.S. Department of Defense (DOD), researchers point out. Spectrum dominance requires quick and efficient control of electromagnetic radiation from DC to the X-ray regime.

The primary challenge of the Macaroni project that SRI and Draper will face involves receivers and transmitters that are much smaller in size than the wavelength of the sent and received electromagnetic radiation.

In classical antenna theory, the sensitivity-bandwidth product is fundamentally limited by the shape and size of the antenna. This performance degrades significantly as the antenna size becomes much smaller than the electromagnetic wavelength of operation.

Yet size-, weight-, and power- (SWaP)-constrained applications are driving efforts to move beyond traditional constraints, and develop efficient, electrically small antennas still presents a challenge.

Related: The puzzle of RF co-site interference

Recent advances in quantum sensors, materials science, electromagnetic shielding, laser technology, resonators, cryogenic systems, and vacuum components have pushed the state of the art in sensing technologies. As these enabling technologies improve, a wider variety of protocols and methodologies become possible and previous notions of the performance limits require validation, researchers say.

For transmitters, new insights in active antenna technology, control schemes, methods of impedance matching, and strategies for volume filling also present new opportunities. Recent efforts in piezoelectrics, magnetoelectrics, high-index materials, and multiferroic materials may be leveraged to improve the efficiency trade space for small antennas.

DARPA researchers are asking SRI and Draper for transmit and receive technologies that can achieve performance beyond the Chu limit that can incorporate electric and magnetic technologies -- especially in solutions that minimize the antenna size relative to the operating wavelength.

Related: SRI International to conduct high-power RF and microwave experiments for space with Stanford dish antenna

The Macaroni program is a 45-month three-phase program with an 18-month first phase, an 18-month second phase, and a nine-month third phase. The project emphasizes two technical areas: receivers and transmitters.

SRI and Draper will focus on receiver work involving receive sensitivity, link closure, and systems integration. The company's transmitter work will focus on transmitter strength, demonstrating a transmitter system, and system ruggedization.

For more information contact the Charles Stark Draper Laboratory online at www.draper.com, SRI International online at www.sri.com, or DARPA at www.darpa.mil/program/macaroni.

About the Author

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.

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