The indoor range, which measures radar cross sections
(RCS) and antenna ranges, includes specialized active
antennas, microwave circuits, and devices that are
governed by underlying electromagnetic physics. RCS is
a strong function of the orientation of the radar and target,
so orienting the target – positioning it accurately within
the radar range – was crucial to the whole measurement
process and was the most critical requirement in the
redesign. As such, ADC needed to build a transportation
system into and out of the radar range that provided
absolutely accurate positioning.
DESIGNING A POSITIONING SYSTEM
The positioning system that ADC developed solved all
the problems the project posed. To bring targets in and
out of the radar range, ADC proposed building railroad
tracks approximately 110 feet long that would be all metal
welded. Two rails would be positioned about four feet
apart and they would traverse the distance to and through
the indoor radar range – imagine a long railroad track
inside a building that contains the radar range. NASA
could roll equipment into the range and shoot it with radar
to see what the radar looks like.
Because NASA wanted to put multiple targets inside
the radar range without having to get a forklift to bring
them in and out, ADC developed the design of a
switching station outside the perimeter of the range.
The switching station would actually be a turntable
similar in operation to switching stations for railroad trains.
Targets atop track sections could be moved on and off
the turntable, which would then turn to align that track
section with the 110-foot long track that would bring
them into the radar range.
The Experimental Test Range, or ETR, rail system
begins in the model prep area of the facility and ends 10
feet past the center of the test chamber. The total length
of the rail system is 112 feet with laser position encoding
for the final section of the rail system. Linear guide rails
are used to support the carriages and each carriage is
positioned with a rack and pinion drive. Rails mount to
steel weldments that are supported with 8 inch diameter
feet. The rail system’s capacity is 7,300 pounds.
The design includes a place to dock positioning
components when they are not in use. Curved linear guide
rails support the switching station so that the platform can
be rotated manually, and hardened tapered pins are used
to align the switching station with mating rail segments.
These rails are custom, case hardened steel shafts with
tapered ends to improve transfer across the switching
NASA recently sought to refurbish and upgrade their old indoor radar range, clearing
out what they had and replacing it with
newer, better-designed equipment.
Specifically, NASA wanted “to put
multiple targets inside the radar range
without having to get a forklift to bring
them in and out. Not only things such
as an airplane, but really anything
that is detected by radar,” explains
Eric Van Every, ADC USA director of
By Larry Hansen, NB Corporation of America
Pylon rail positioning component. (All image credit: NB Corporation)