Electromagnetic Compatibility Measurement Procedure for Vehicle Components-Immunity to Radiated Electromagnetic Fields, 10 Khz to 1000 Mhz-Tri-Plate Line Method
Authors:   Electromagnetic Compatibility (EMC) Standards
Published: March 2017

<p>This procedure covers the recommended testing techniques for the
determination of radiated immunity of an automotive electronic
device. This technique uses a Tri-Plate Line (TPL) operating over a
frequency range from 10 KHz to 1000 MHz. This technique is limited
to components which have a maximum height of equal to or less than
1/3 the height between the driven element and the outer, ground
plates.</p>
<p>A TPL, a variation of a TEM cell design, is constructed without
sides to the cell. The primary advantage to the use of the TPL as
opposed to a TEM cell is that its construction permits large
devices to be placed within the cell with their associated cables
attached without special feed through ports or adapters as required
for a TEM cell. The lack of sides which would be found in a TEM
cell permits easy routing of the cables to and from the Equipment
Under Test (DUT).</p>
<p>The TPL does not have a serious problem with fields reflected
from the side walls as does with the TEM cell. This permits its use
to frequencies above that of a TEM cell of the same physical size.
Note that although the construction of the TPL limits generation of
uniform electric and magnetic fields to frequencies below 500 MHz,
experience has shown that the TPL may be used at frequencies up to
1 GHz and still provide reasonable and repeatable test results.
This may only occur if the test setup requirements (i.e., DUT plus
1 meter of cable) and characterization procedures, delineated in
this SAE Standard permits its use to frequencies above that of a
TEM cell of the same physical size. Note that although the
construction of the TPL limits generation of uniform electric and
magnetic fields to frequencies below 500 MHz, experience has shown
that the TPL may be used at frequencies up to 1 GHz and still
provide reasonable and repeatable test results. This may only occur
if the test setup requirements (i.e., DUT plus 1 meter of cable)
and characterization procedures, delineated in this SAE Standard
are followed.</p>
<p>The lack of side walls also means that the TPL must be used
within an RF shielded enclosure to prevent RF energy, radiated from
the TPL from interfering with near-by electronic devices. To
prevent potential resonances and reflected waves within the
shielded enclosure from distorting the fields produced within the
TPL, the test chamber walls and ceiling must be lined with RF
absorbing material. These issues are discussed in greater detail in
the body of this are followed.</p>
<p>The lack of side walls also means that the TPL must be used
within an RF shielded enclosure to prevent RF energy, radiated from
the TPL from interfering with near-by electronic devices. To
prevent potential resonances and reflected waves within the
shielded enclosure from distorting the fields produced within the
TPL, the test chamber walls and ceiling must be lined with RF
absorbing material. These issues are discussed in greater detail in
the body of this document.</p>
<p>CAUTION--Hazardous voltages and fields exist on and near the TPL
when the equipment is energized. Test personnel should ensure that
no one is in the test chamber during a test. It is the intent of
the EMI committee to withdraw this document in five years unless
there is a demand to retain the document</p>