Microwave hurricane hunter

Microwave hurricane hunter
Date:31 December 2008

When it comes to testing high-tech weather sensors, scientists enter a different kind of quiet room.

Quality testing a new, ultra-sensitive weather radar requires a room that is guarded from any conflicting emissions. When the National Oceanic and Atmospheric Administration’s Hurricane Imaging Radiometer, HIRAD, needs some electromagnetic tranquillity to test its ability to scan the ocean from an aircraft or satellite, researchers place it in an anechoic chamber at a Nasa research centre in Huntsville, Alabama. Because the sensor calculates wind speed using microwave reflections off the ocean’s frothy waves, the instrument’s accuracy must be tested in an electromagnetically silent room. The eye-dazzling patterns of radio frequency-damping material inside the chamber minimise interference. This ensures that the HIRAD antenna picks up only emissions from a source on the other side of the chamber, providing data on the antenna’s sensitivity.

Small scanner
The HIRAD antenna has no moving parts and may be light enough to fly on aerial drones.

Wide angle
When flying in an aircraft at 10 000 m, HIRAD can scan 35,4 km2 miles of ocean.

Sharp pattern
Pyramids of carbon-impregnated rubberised foam scatter and dissipate RF signals.