April 26, 2016: Jim Marr AA6QI: Building a quadrifilar helicoidal antenna for satellite work
While in the back of his mind for many years, Jim became seriously interested in working amateur satellites after sitting with Tom Mikkelsen WA0POD during Field Day 2015 and decided to make it happen. This talk describes Jim’s adventures in building and using one type of antenna suitable for satellite communications: the quadrifilar helicoidal antenna (or QHA) first described in 1970 by C.C. Kilgus at Applied Physics Laboratory, since used on many satellites (e.g., AMSAT-OSCAR 7) and by many, many amateurs for their ground station antennas.
Jim Marr AA6QI was first licensed in 1965 (as WB6LOA), but was relatively inactive through a substantial part of his working years. He is actively enjoying the hobby again since his retirement in 2015. Jim has a BS in Engineering and Applied Sciences, and an MS in Mechanical Engineering, from Caltech. His professional life included seven years with the U.S. Navy operating submarine nuclear power plants; four years with Tetra Tech, Inc. leading their Marine Systems and Services Department; and 31 years with NASA’s JPL, mostly doing line and project management. One of his most significant project activities was leading the team that reprogrammed the Galileo Jupiter spacecraft while in flight to Jupiter, and simultaneously redesigned the NASA Deep Space Network to support Galileo’s mission at Jupiter using Galileo’s S-band 7 dBi low gain antenna after the X-band 43 dBi high gain antenna failed to deploy.