Radar is a vital tool for investigating how radiowaves propagate in
all conditions, whether in clear air, in rain and snow or through thick
cloud. RCRU runs the world's largest steerable meteorological radar at
its Chilbolton Observatory in Hampshire. The radar, known as CAMRa (Chibolton
Advanced Meteorological Radar) has dual-polarisation capability, which
means that it can transmit and receive both horizontally and vertically
polarised radio pulses.This makes it possible for researchers to find
out the shape and orientation of cloud and precipitation particles in
the atmosphere. It also has full 'Doppler' capability, allowing the radar
to map wind direction. The radar is mounted on a 25 m antenna that generates
a very narrow beam a quarter of one degree wide. This narrow beam can
resolve objects only 400m in size at a distance of 100km. CAMRa operates
at 3 GHz, to ensure that its signals are attenuated or faded as little
as possible.
CAMRa supports many projects both within the RCRU and in the wider Cloud
Physics and Remote Sensing research communities. Researchers measuring
earth-space satellite signals use CAMRa to investigate fading caused by
episodes of bad weather. The team monitoring terrestrial high frequency
links in Winchester and Southampton also rely on CAMRa to provide them
with meteorological data. The Chilbolton radar data is particularly useful
for simulating how radiowaves are likely to behave in particular hypothetical
scenarios. Researchers wanting to know how a system will function at a
certain frequency in a particular set of weather conditions can use the
Chilbolton data to answer their specific questions without having to build
and test a real link.
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