Seeking next-gen antennas? Remain flexible.
This article originally appeared in the Sept. 2, 2019 issue of SpaceNews magazine.
Satellite operators ranging from lean startups to powerful defense agencies are experimenting with flexible materials that fold compactly for launch and expand in orbit to create large communications antennas.
DARPA’s 150-kilogram Radio Frequency Risk Reduction Deployment Demonstration (R3D2) satellite is a high-profile example. Sent into low Earth orbit in March on a Rocket Lab Electron, R3D2 is equipped with a reflectarray antenna made of a lightweight flexible membrane by MMA Designs. The antenna, packed tightly inside the Northrop Grumman satellite for launch, unfurled in orbit to extend 2.25 meters in diameter.
While DARPA is still evaluating the antenna’s “dynamics, survivability and radio frequency characteristics,” the R3D2 program has already been successful in demonstrating the rapid acquisition of a small satellite and launch “as well as the successful deployment of the high compaction ratio antenna,” Jared Adams, DARPA communications chief, said by email.
Large antennas that stow compactly in satellites allow “satellite owners to take advantage of volume-limited launch opportunities while providing significant capability. Additionally, this capability could enable communications to disadvantaged users on the ground without requiring the use of a larger transmitter,” Adams said.
Deployable antennas are a popular choice for spacecraft developers, who have trimmed spacecraft size to reduce launch costs but still need large antennas to communicate with mobile devices on the ground.
“The challenge and the opportunity is creating the largest possible antenna you can fit in the smallest possible space,” said Mike Lawton, CEO of Oxford Space Systems, a firm he established in 2013 in the United Kingdom’s Harwell Space Cluster precisely to fill this niche.
Lawton is not alone in pursuing this opportunity. Antennas that store compactly for launch and extend in orbit are being developed and flown by space industry giants Northrop Grumman and L3Harris Technologies as well as smaller firms like MMA Designs of Louisville, Colorado, and Helical Communications Technologies of Rockledge, Florida.
The R2D3 antenna, which stows in the volume of a 10-unit cubesat, comes from MMA Designs’ family of Deployable High-Gain Reflectarray antennas. That family includes the one-square-meter Tape Deployable high-Gain Reflectarray Antenna that packs in a single cubesat.
Initially, MMA Designs developed deployable antennas with internal research and development dollars. In the last three years, though, government and commercial customers have shown greater interest in the technology and provided money to accelerate antenna development and conduct flight tests. “It’s all part of the small satellite wave,” said Mitch Wiens, MMA Designs president.
Lawton also notes growing interest in deployable antennas particularly from government agencies and companies planning constellations of satellites to connect devices in the Internet of Things.
Oxford Space Systems expects its first deployable antenna to reach orbit in November, a helical antenna on one of four prototype satellites Lacuna Space plans to launch as it evaluates technologies for an Internet of Things constellation.
In addition, Oxford Space Systems is developing a “Wrapped Rib” antenna comprised of carbon fiber composites encircling a central hub for the United Kingdom’s Ministry of Defence.
“When we allow it to deploy, those ribs want to return to the starfish position and in doing so tension the antenna surface to give us a parabolic antenna in orbit,” Lawton said. Oxford Space System’s Wrapped Rib antenna is scheduled to reach orbit in early 2021 as part of the Project Oberon, a Ministry of Defence campaign to develop a constellation of synthetic aperture radar satellites.
In addition to antenna builders, some small satellite developers are developing their own deployable antennas. At the Small Satellite Conference in Logan, Utah, in August, Israel’s NSLComm showed a deployable antenna made from flexible composite material.
NSLComm launched its first six-unit cubesat built by AAC Clyde Space in July on a Russian Soyuz rocket. On July 28, NSLComm unlocked the antenna, which was folded snugly in a volume of less than a single cubesat. It sprang loose to form a 60-centimeter Ka-band antenna.
NSLComm plans to spend another month evaluating the performance of the antenna in orbit for potential applications including cruise ship communications and connected cars.
“Because we have such big sensitive ears in space, we can have a very small terminal on the ground,” said Daniel Rockberger, NSLComm co-founder and chief engineer.
With 22 employees, NSLComm does not plan to build its own global communications constellation. “We know that’s not possible. We need partners,” Rockberger said.
For example, NSLComm might establish partnerships with a satellite communications provider, a mobile network operator and a satellite manufacturer.
“We are already building that consortium,” Rockberger said. “When we have all those building blocks in place we hope to start building the first belt of the constellation in equatorial orbit. Then we’ll grow to offer world coverage.”