VLA L-band feed horn

Trucking a Giant Feed Horn

The L-band feed horn is one of the largest feed horns used on our radio telescopes. The size of a feed horn is related to the size of the wavelength that it funnels onto its receiver. L-band wavelengths are 20 centimeters long, so the narrow end of this horn is 20 cm wide where it turns the wavelength into a voltage. If the open end were less than 20 cm across, the waves would simply see it as a mirror, and bounce away. The wider the mouth of the horn is, the more waves can enter the receiver without being lost.

The VLA
VLA antennas and transporter

Looking Down the Line at the VLA

The 27 antennas of the Very Large Array in New Mexico sit on piers adjacent to a double-track railway. Several times a year, antennas are pulled from their pads and hauled away down the tracks on the backs of Antenna Transporters, the orange-red vehicle seen in this shot. By spacing the antennas farther apart from each other, we increase their binocular vision which makes them see more detail.

VLA antennas

Indigo Skies Over the VLA

Our atmosphere is filled with water vapor whose molecules just happen to wiggle enough to emit frequencies that interfere with the waves coming from space. Radio telescopes, such as the Very Large Array seen here, are built in high, desert locations such as central New Mexico to take advantage of the thinner, drier atmosphere.

VLA antennas

Long Distance Shot of the VLA

The view west of Magdalena, New Mexico during monsoon season. Rain pours down over the 27 antennas of the Very Large Array.

Dave Ehnebuske