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These stability and repeatability results are well within
the requirements stated in RTCA/DO-213.
The following tables and plots show some typical test
results for both a typical Kevlar (Class C) and a high
quality quartz glass (Class A) radome. Note that the
shown tables and graphs are generated fully automated.
Customer specific logos, test object information and
signature fields can be added according to the customer
requirements.
Figure 5. Transmission Loss of typical Kevlar radome
Figure 6. Sidelobe Increase of typical Kevlar radome
Figure 7. Transmission Loss of high quality quartz glass
radome
Figure 8. Sidelobe Increase of high quality quartz glass
radome
6. Measurement times
In the spherical NF measurement system, the phi-axis
rotates at 30 rpm, thus makes one revolution in 2 seconds.
The theta axis, which is the step axis, needs approx. 2
seconds to move to the next theta position.
A large radome, like on a Boeing 747, requires an
acquisition step angle of 0.72 deg. This presumes that any
part of the radome can reflect some radiation (eg.
reflection lobes), which is the worst case assumption.
For a full characterisation of the radome / antenna system
the theta axis needs to be scanned from 0 (zenith) to
slightly beyond 90 degrees (horizon), resulting in approx.
9 minutes for a single measurement. A fully compliant
RTCA “after repair” test requires 45 gimbal positions at 2
“quarter wavelength” positions of the antenna, plus two
reference measurements, or a total of 92 measurements.
Thus the total measurement time for a B-747 radome is in
the order of 14 hours.
A smaller radome, like used on a DASH, requires 1.44
deg increments, and results in total measurements times
in the order of 8 hours.
These test times have been confirmed in practice.
Although the test times for the largest types of radomes
are quite long, it must be realized that the facility operates
fully automated, and no operator actions are required
from after the radome is mounted until all 2 x 45 gimbal
angles are measured and the radome can be removed
again. Thus, in practice, one to two radomes can be
measured per day, which is typically more than sufficient
for a radome repair workshop.
If higher measurement speeds are required, then more
probes can be mounted on the elevation arm.
7. Conclusions
A very compact RTCA/DO-213 compliant “after repair”
RF test facility has been build and qualified, but also
Qualification / Preproduction and Quality Assurance /
Production Testing defined in RTCA/DO-213 can be
tested with this facility.
It can be installed in the repair workshop and can be
operated by workshop personnel. Tests are made and
evaluated fully automated.
Since this avoids packing for and transportation to an
external RF test facility, significantly reduced repair times
can be realized.
8. REFERENCES
[1] “Minimum Operational Performance Standards for
Nose-Mounted Radomes” dated Jan 14, 1993, with
“Change No. 1 to RTCA/DO-213 Minimum Operational
Performance Standards for Nose-Mounted Radomes”,
dated Jun 23, 1995,
[2] “CMM Component Maintenance Manual”, various
Aircraft models, Airbus Industrie,
Radar Contact
Version 4.3
www.jdtllc.com
Radar Contact Table of Contents
Version 4 December 2, 2007
Copyright JDT LLC 2005 Page 3
Introduction .............................................................................................................................. 11
What is Radar Contact? ........................................................................................................ 11
Who Should Use Radar Contact? ......................................................................................... 11
What is New in Version 4 .................................................................................................... 12
What is in Radar Contact - Feature List ............................................................................... 13
Comparison Chart ................................................................................................................ 14
System Requirements ........................................................................................................... 17
Quick Start Guide ..................................................................................................................... 21
Step 1 - Install Radar Contact .............................................................................................. 21
Step 2 - Develop your Flight Plan ........................................................................................ 26
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