A team of engineers and scientists from the National Radio Astronomy Observatory (NRAO) and Virginia Tech have successfully demonstrated a new antenna feed system for the Very Large Array (VLA). The VLA is one of the world's premier astronomical observatories, consisting of 27 25-meter dish antennas located in central New Mexico.
The new feed system was designed by Steve Ellingson, an associate professor in VT's department of electrical computer engineering, and Mahmud Harun, a VT Ph.D. student who graduated in 2011. The prototype installation and test program was led by Dr. Frazer Owen, a senior astronomer at NRAO.
The new feed system allows the VLA to observe continuously from 54-85 MHz, replacing a previous system with much narrower bandwidth and which was only intermittently installed due to interference with the VLA's higher-frequency systems. The new system avoids the interference problem by using four dipole-like elements lying outside the signal path used by the higher-frequency systems, and combining them to create signals equivalent to those from dipoles located in the nominal, but interfering, locations. The increased bandwidth is obtained by replacing the dipoles with a novel antenna element purpose-built for this application.