Abstract.
The results of electromagnetic
interference measurements are actual for the estimation of information security
from signal leak on conductive line. Received experimental regularities can be
used also for construction and updating of analytical models of information
leakage channels. Usually, technical equipment is located inside multistorey
buildings. In this connection for the estimation of spurious signal attenuation
in a line it is necessary to consider the influence of closely located objects on
the distribution of the current and near field. The article considers a simplified
model for the formation of interference in a thin wire, located in a room of a
multistorey building in close proximity to the absorbing surface in the form of
a concrete floor. The harmonic generator with symmetric antenna was used as an
external radiation source. Two typical orientations of the antenna with respect
to the wires of the line are considered: the axis of the antenna is parallel
and perpendicular to the wire. Based on the moment method, the level of electromagnetic
interference in a thin wire with isolation was calculated. Also it was taking
into account the influence of the underlying close located surface. The
comparative analysis has shown good enough correspondence of experimental
researches results and numerical calculations. We revealed the significant
effect of close located surface and the orientation of the radiating antenna to
the signal attenuation in the line. Thus, the attenuation of electromagnetic
interference is not a characteristic of individual lines. It describes a system
consisting of radiation source, conductive line and surrounding space near the
conductor line. It is shown that the level of signal attenuation along the line
varies non-uniformly, and on certain sections the amplitude of the induced
current does not change. Therefore to analyze the level of interference in the
lines it is incorrect to use widely known theory of long lines. It is proposed
to consider the electromagnetic problem of determining the currents induced in
the line by external electromagnetic field taking into account the influence of
the surrounding space.
Keywords: compromising
emanations, experimental researches, information protection, attenuation of
signals, numerical methods.
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