Innovators at NASA Glenn developed the Conformal, Lightweight Antenna for Aeronautical Communications Technology (CLAS-ACT), an active phased array antenna for Ku-band satellite communications on a mobile platform such as a UAV. The CLAS-ACT was developed for UAVs that require operations outside of radio line of sight that use a satellite link to increase operational coverage for command and control. The satellites typically used for this application fly a geostationary orbit at a very high altitude.
The current state of practice for UAVs traveling out of line of sight is to use a large parabolic dish antenna that is pointed with a mechanical gimbal; this requires a significant volume within the UAV, adds unnecessary weight, and demands a large amount of power. The CLAS-ACT antenna improves upon current practice by offering a lightweight, small-sized antenna that can be mounted on the curved frame of an aircraft and has advanced beam steering/beam synthesis capabilities, enabling the efficient command and control of small or large UAVs used for a variety of purposes.
The CLAS-ACT is comprised of a thin multilayer microwave printed circuit board built on a flexible aerogel substrate using new methods of bonding. The aerogel substrate enables the antenna to be fitted onto a curved surface. The prototype operates at 11 to 15 GHz (Ku-band) but the design could be scaled to operate in the Ka-band (26 to 40 GHz).
The antenna element design incorporates a dual stacked patch for wide bandwidth to operate on both the uplink and downlink frequencies with a common aperture. These elements are supported by a flexible variant of aerogel that allows the material to be thick in comparison to the wavelength of the signal with little to no additional weight. The conformal antenna offers advantages of better aerodynamics for the airframe and potentially offers more physical area to either broadcast further distances or to broadcast at a higher data rate.
The intended application for this antenna is for UAVs that need more than line of sight communications for command and control but cannot accommodate a large satellite dish. Examples may be UAVs intended for coastal monitoring, power line monitoring, emergency response, and border security where remote flying over large areas may be expected. Smaller UAVs may benefit greatly from the conformal antenna. Another possible application is a UAV mobile platform for Kuband satellite communication.
This technology may be of interest to other markets outside of satellite communications; for example, the automotive industry could benefit from a lightweight conformal phased array for embedded radar. Also, the CLAS-ACT could be used for vehicle communications or even vehicle-to-vehicle communications.