Photo – Page 49 – National Radio Astronomy Observatory

Electronics Innovations

Aidan Hotan, a radio astronomer visiting Green Bank from Australia, shows off a complex circuit board he designed.

In this artistic shot taken in the 1970s, the piers of the Very Large Array stand empty. That is because there were not yet any antennas to place on them! The VLA has 72 pads for 27 antennas, and those pads are used when the antennas are moved farther and farther apart throughout the year.

VLA’s Original Hybrid Lens

The original design of the Very Large Array antennas used a hybrid lens between the subreflector (bowl at top) and the receivers (off camera below).

This strange-looking contraption gathered radio waves coming off the subflector into tighter formation before they entered the narrow funnels (feed horns) on the receivers. The nested rings in the center of this structure act like a Fresnel lens to bend inward radio waves that are farthest apart and slow down radio waves in the very middle to keep in formation. The ring of cylinders act like wave guides for the important 21-cm waves that come from neutral hydrogen.

An Early VLA Antenna Move

After assembly or maintenance is completed inside the Antenna Assembly Building, a Very Large Array antenna is carefully lifted and hauled back out into the array on board an antenna transporter. The transporter rides the rails that form a large Y-shape across the San Agustin Plain in central New Mexico.

Half of the VLA's original supercomputer

Half of a Supercomputer

This is half of the original supercomputer used by the Very Large Array from 1979 until 2009. It used over 650 printed circuit cards with 85,000 integrated circuits, and it required 50,000 watts of power. It works as a correlator, performing 1.7 trillion operations a second to combine the waves received by 351 pairs of VLA antennas into a single set of data. The new correlator that replaced this one is 1000 times faster.

Original Correlator for the VLA

Here is a close-up view of the original correlator for the Very Large Array used from 1979 until 2009. It used over 650 printed circuit cards with 85,000 integrated circuits, and it required 50,000 watts of power. It works as a correlator, performing 1.7 trillion operations a second to combine the waves received by 351 pairs of VLA antennas into a single set of data. The new correlator that replaced this one is 1000 times faster.

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