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support plate with radome into and out of the facility.
This action only takes a few minutes.
3. Facility Control
The operation of the facility is highly automated for the
measurement types described in the RTCA/DO-213, and
minimum antenna and RF knowledge is necessary to
perform these tests according to the RTCA/DO-213
requirements. The measurements can typically be
executed from fully automated batches, provided by
ORBIT/FR.
On the other hand, there is still a lot of flexibility in
regard to variation from the pre-defined measurements.
Such variation can consist of selecting a sub-set of the
gimbal angles (e.g. to concentrate on an area of the
radome where improvement or repair is necessary) and of
selecting reduced RF sampling ranges (e.g. to speed up
measurement time for indicative measurements).
3.1 Test facility and test preparation
Presuming the facility is powered off, first the test facility
needs to be powered on, temperature stabilize and the
applicable radar antenna needs to be mounted (if there is
a large variation in the sizes of the radomes to be tested,
also the radar antennas need to be available in different
diameters). Then data is entered in regard to the test
radome (e.g. Type and Serial Number).
Detailed instructions for the operator appear on the
computer monitor.
3.2 Measurement selection and execution
First the test standard is selected (RTCA/DO-213 resp.
CMM or customer defined “Fast Check”), the
measurement types are selected (Transmission Efficiency,
Side Lobe Levels and Beamwidth, Incident Reflection
and / or Beam Deflection). Note that for “After Repair
Testing” only Transmission Efficiency and, in some
cases, Side Lobe Level Increase are required.
Then the gimbal angles are selected (full set, as defined in
RTCA/DO-213 resp. CMM, or partial set).
Before measurements can be started, the temperature of
the facility needs to be stabilized to within ± 2 deg of the
reference temperature (see also Chapter 2), each time the
large doors have been opened. Note that if the reference
temperature is close to the temperature outside of the test
chamber, no waiting times would be required.
Now a calibration (reference) measurement is made of the
radar antenna without the radome. Then the radome is
mounted and, after the temperature is stabilized again, the
measurements can be performed fully automated. At the
end of all measurements the radome is removed again,
and a second reference of the radar antenna without
radome is performed to verify that the facility was stable
during the measurements.
3.3 Data Analysis and Reporting
After the measurements are finished, test reports are
generated automatically. For “Fast Check” or “Partial
Check” the statement at the lower end of the report will
then state that these measurements were NOT executed in
accordance to RTCA/DO-213 and / or CMM.
4. Safety
Many safety aspects have been included in the design and
implementation of the Radome Test Facility. These
aspects relate to both equipment safety (test facility
including radar antenna and radomes) as well as
personnel safety.
4.1 Equipment Safety
The equipment safety relates to the risk that any
component of the test facility, or the radome under test,
can get damaged in operation. In particular, if many
different sizes of radomes are to be tested, then such a
risk is real: if a large radome was measured, and after that
a much smaller radome is to be measured, then the radar
antenna could hit the radome wall if the facility would not
correctly be set up to handle the much smaller radome.
If the system is only used for regular weather radar tests,
then it is only operated at frequencies from 9.3 to 9.5
GHz. Thus nothing needs to be changed to the RF
instrumentation, including the RF probe, at any time. The
RF probe on the elevation arm is normally parked at the
ceiling of the facility near the “zenith” position when any
person has to work inside the facility. This reduces the
risk that the arm and the RF probe are damaged during
installation work.
Before the radomes are installed in the facility, they are
fitted to support plates unique to the radomes, with
handles or other devices to carry the plate / radome
assembly. The radomes are mounted upright on the
azimuth positioner (the aircraft is “flying” to the zenith of
the facility). This makes the assemblies easy to carry and
install. It will be difficult to install a radome on the wrong
support plate by virtue of clear indications and
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