RTCA DO-160 Section 20 Working Group

1
RTCA DO-160 Section 20 Working Group

• Billy M. Martin
• Cessna Aircraft

2
Meetings

• Task Group conducted a telecom on Thursday Oct.
  16th
• the philosophical and technical discussions on
  susceptibility mode stirring and mode tuning.
• Current procedure of Mode Tuning is too complex
  and as such is not being used
• Stirring Technique does not have to be as good
  as mode tuning, but only be as good as the
  current standard of spot illumination in terms
  of
• Robustness and Repeatability
• Group understands that there are limitations to
  the procedures and that improvements will need to
  be made, however the desire to have a simple
  straight forward procedure that can be improved
  upon, rather then one that no one is using is
  helping to drive the effort.

3
Status

• The group decided to
• insert mode stirring procedures, and remove mode
  tuning steps that weren't applicable to mode
  stirring.
• Jeff Phillips from Cessna provided a draft which
  will be the starting point for this revision.
• Plan to distrubute the revised section to the
  task group for discuss and will present an
  acceptable revision to the full committee by the
  next meeting
• Need agreement from general committee in regard
  to the approach

4
Additional Issue

• Spot Illumination Requirements for additional
  aspect anlges
• This proposal was agreed upon prior to Rev F
  however was not incorporated
• REV F_537 is shown as withdrawn but that was a
  mistake, it was not withdrawn It was approved at
  the joint WG14/SC-135 meeting at Marseille
• Agreed to re-visit spot illumination aspect
  angle proposal
• Proposal concerning Antenna Distance

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Proposed Text

• RS Test Set-up
• Set up the EUT, wiring, associated interface
  circuitry and test equipment per Figure 20-2.
• Signal generators, amplifiers, antennas and
  probes shall maintain required RF field levels to
  properly illuminate the EUT and interconnecting
  wiring. Position and aim antennas to establish
  the RF field strengths at the EUT and
  interconnecting wiring. Define the 3 dB points
  of the radiated field using antenna beamwidth
  specifications, or by mapping the area in which
  the EUT is to be placed. The beamwidths of the
  antennas used in the test should be stated in the
  test report. When the 3 dB beamwidth of the
  antenna does not totally cover the EUT and
  wiring, perform multiple area scans. Vertical and
  horizontal transmit antenna orientations are
  required.
• Directly expose each face of the EUT that
  contains apertures (e.g., displays, CRTs,
  connectors) to the transmitting antenna. Any face
  that was not exposed to the transmitting antenna
  has to be justified in the test form.

6
Antenna Position

• Revise Toc. Radiating Antenna Position
• The separation distance between the antenna and
  the EUT and wiring should be one meter or
  greater. If the transmitting antenna being used
  is a pyramidal horn or similar radiator, as the
  dimensions of the antenna become small and the
  frequency of interest becomes higher, it is
  permissible to move the antenna closer to the EUT
  and wiring than one meter. This can only be done
  when the far field distance of the transmitting
  antenna is less than one meter.
• The position of the transmitting antenna
  relative to the EUT must remain equal to or
  greater than the far field distance of the
  transmitting antenna. If the far field distance
  of the antenna is greater than one meter then the
  standard one meter separation should be used.
• The far field distance is calculated by the
  formula (2D)2/?, where D is the largest
  dimension of the antenna, and ? is the wave
  length of the lowest frequency of interest for
  that antenna.
• If the test is to be conducted in shielded
  enclosures with anechoic material, then the
  antenna should be at least 0.3 m away from the
  absorber surfaces.