Researchers at NASA’s Armstrong Flight Research Center have developed an innovative antenna-mounting platform that addresses an unmet need in the unmanned aerial vehicle (UAV) market.
Research UAVs often have multiple transmitters and receivers on the aircraft and on the ground. This equipment emits radio frequency (RF) signals that include video, command and control, and signals to and from the UAV as well as the research data of interest. Therefore, multiple antennas must be pointed at a single UAV.
Until NASA Armstrong’s innovative design, a low-power, low-cost, portable, multiple-antenna platform option for tracking UAVs did not exist. Most low-cost platforms support only one antenna per unit and have limited/slow rotational capabilities. Although some platforms overcome these limitations, these high-performance units were developed for military applications, cost up to $100,000, and often require proprietary ground stations and radio systems.
NASA Armstrong researchers found a middle ground between the low-end tracking platforms that support only one antenna and the ultra-expensive, high-end options. They designed a platform that meets the multi-RF requirements for UAVs at a price tag below $5,000.
NASA Armstrong’s portable, continuously rotating autotracking platform can hold and position nearly 60 pounds of interchangeable antennas of any type, including Yagi-Uda, dish/parabolic, omnidirectional, and/or patch, while maintaining full rotation speed. It is ideal for lightweight, low-power (<10 W) transmission antennas and radios. It is also light enough that a single person can carry it.
The design includes a horizontal bar for mounting antenna equipment that incorporates attachment pieces, which eliminates the need for additional load-balancing hardware. This simple setup also allows antenna equipment to be very close to the axis of rotation, thus minimizing the moment of inertia for the elevation motor and enabling smaller, less costly motors to be used.
The software can interface with any ground station that can provide the GPS coordinates of the target being tracked and of the tracking antenna(s). A microcontroller interface receives antenna commands from the software and drives the motors. The platform runs all power and signals through robust, inexpensive electrical slip rings, enabling any frequency of RF links to be used while also eliminating the need to “unwind” and lose telemetry connection with the object being tracked.
Powered by 120 VAC and updating its aiming position at a frequency of 30 Hz, the platform moves all of the antennas and other equipment simultaneously in continuous rotation in azimuth and ±180 degrees of rotation about the elevation axis, maintaining line-of-sight tracking 20 miles away (or farther, depending on transmit power and antenna configuration).
This easy-to-manufacture, frequency-agnostic platform works with any moving system needing to transmit large quantities of data over one or more RF links. It is perfect for use with small UAVs for various applications, including law enforcement and surveillance, atmospheric and Earth science research, agriculture (e.g., crop spraying), monitoring/protecting animal species, marine communication (within line of sight), and tracking low-Earth-orbit satellites, sounding rockets, weather balloons, etc.
Furthermore, as Congress contemplates opening up the U.S. airspace for commercial use of UAVs, the market potential for this innovative platform dramatically increases.