Antenna

Current state-of-the-art mesh antennas use ribbed umbrella and hoop structures for deployment. While these are potentially scalable to some extent, they inherently have high parts counts and require significant touch labor at a high number of attach points to form the desired mesh surface. These systems have constraints on their stowed volume which present challenges with small launch vehicle fairings and dispensers. The DaHGR sets a new standard for deployable antennas with 13 the parts count, less than 15 the volume (with a more favorableflexible aspect ratio), and 13 the cost of current SOA deployable mesh antennas.

MMA successfully developed a deployable RF antenna structural system that can be scaled and leverages space heritage of mechanisms utilized on other similar deployable systems. The goal of this program was to develop an antenna whose entire footprints could be stowed within a Minotaur IV. Earlier development versions designed by MMA were over twice as large, but by using a modular system, and utilizing legacy technology developed and deployed on previous missions, MMA was able to create a solution that met challenging mission requirements with high reliability and low mass.

The patent pending MMA Spine APM uses a stack of pivoting vertebra elements forming a spine. The spine cross-section has a hole in the center, similar to the spinal cord in the backbone, where a flexible RF coaxial cable or wave guide is routed. The curvature of the spine assembly is shallow and repeatable, thus minimizing the bend radius of the FR coaxial cable or wave guide. This approach eliminates complex rotary joints and their associated RF losses and preclude the need for rotate or twist the aperture while pointing.
Within the spine there are four tensioned cables. Two of the cables are attached to stepper or brushless DC motor driven reels. The other two cables are held under constant tension by extensible springs. To actuate the spine assembly to any point within the pointing range 2 of the 4 cables that control the spines position and curvature are extended or retracted by the appropriate reel. Changing the cable lengths moves the APM to a predetermined position. Testing at MMA has proven the APM pointing angles are very repeatable.