The following provides a list of major test equipment, engineering software, and other resources available at the NRAO site in Green Bank, WV.
An ethernet local area network is available in all offices and laboratories, providing access to shared computer resources and the internet.
An outdoor antenna range is located on the Green Bank site. Two 32 foot towers, one fixed and one movable, give range distances of 12 to 48 feet. The motor-driven feed positioner on the fixed receive tower allows lateral and focus movements as well as azimuth sweeps of the feed under test. A Scientific Atlanta 1754 receiver, and a series of harmonic mixers and standard transmit horns, allow feeds to be measured at most frequencies between 100 MHz and 40 GHz.
A shielded anechoic chamber measuring 15 by 15 by 37 feet is located in the Jansky Laboratory at Green Bank. This chamber has been outfitted as a far-field antenna range. The anechoic chamber was designed and specifed for the frequency range 10-94 GHz. The absorber in the room is a combination of AEP-6 and AEP-8; this absorber is described in this data sheet. Maximum distance from transmit to receive antennas is 22 feet. Instrumentation for the range allows far-field measurements from 2 to 115 GHz, but the actual range possible depends upon the size of the feed, the dynamic range requirements, and other constraints.
Orbit/FR's software package (FR-959) allows fully-automated control of the range receiver, and of all positioners.
The range can be used in two physical configurations. Test items and source antennas may be mounted 7-1/2 feet above the floor of the chamber (along the axis of symmetry of the chamber) to minimize reflections. Above approximately 40-50 GHz, shorter supports (approximately 3-feet above the floor) may be available in the future for greater mechanical stability. The short supports may also be used at any frequency for greater convenience in mounting the antenna under test, if minimizing reflections is not an issue.
Below 50 GHz, measurements are made using the Agilent 83050 upconverter. The user has full use of all polarization positioners.
Above 50 GHz, extension heads from Oleson Microwave are used. There were bought and are normally used with an Anritzu "Lightning" Network Analyzer and cover the frequency range of 60-90 GHz and 75-115 GHz.
Polarization positioners may not be used above 50 GHz as we have no rotary joints for these frequencies. Polarization changes during test must be made manually.
Presently, we have no equipment available to use for measurements from 50 to 60 GHz. Some overlap with reduced preformance from the specified frequency ranges of the Agilent 83050 and the Oleson Microwave heads is expected, but we will not know how well this will work until we try it. If operation in that frequency range is needed, please contact Gary Anderson (GB-2317) to discuss the matter.
The shielded anechoic chamber (described under Indoor Antenna Range) is a useful facility for measurement of RFI emissions from equipment, either purchased or designed in-house. Instrumentation available allows absolute measurements from 100-1000 MHz.