3.3 Radar Targets Scattering Matrix
29
3.3 Radar Targets Scattering Matrix
As it was mentioned above, one of the main tasks of radar location concludes in
conducting of classification of detected target, i.e., in determining of its reflecting
characteristics, dimensions, configuration and spatial orientation.
Radar location can be examined as a tool of remote sensing of radar targets,
which can be any research objects including sea and aerial vessels, unmanned aerial
vehicles (UAVs), space vehicles, and ground surface and hydrometeorologicals. An
information carrier on radar targets is a scattered electromagnetic wave registered by
a receiving radar device integrated in a radar station (radar). At any processing technique of radar signals, the desired information can be retrieved and then interpreted
only via comparison of transmitted and received electromagnetic waves.
During solving of air traffic control (ATC) tasks, the radar and targets in the most
cases are located on a quite far distance from each other that permits to consider
incident wave in neighborhood of a target and scattered near an antenna—as a
flat one—which can be described using only one electric vector E. Limiting by
a case of single-position radar location, when receiving and transmitting antennas
are combined in a space that is specific to ATC radar, finally, the problem of data
acquisition on radar targets leads to comparison of electric vector of radiated E rad
and received E rcv electromagnetic waves of an antenna.
At such comparison, the essential role is for range from a radar to a target, D,
which is easily considered; based on that, radiation field falls as 1/D; accordingly for
the purpose to avoid overloading of resulting relations, a field scattered by a target
in direction to a target (reflected wave) can interpret as E rcv .
In radar location, as it will be explained in detail further, in the most cases, the
narrow-band signals S(t) are used, for which, according to Hilbert, the following
representation is admitted:
S(t) = A(t) cos(ωt + ϕ(t) + ϕ 0 ),
(3.23)
where A(t) and ϕ(t) are some slowly varying functions per high frequency period T
= 2π /ω, ϕ 0 is initial phase, which at this review does not play an important role;
consequently, we will read it as ϕ 0 = 0.
In teaching materials on radio-engineering, particular on radar location, it often
uses its formulation in a complex form instead of (3.23) representation relying on
the fact that: A cos(ωt + β) = Re
Ae
jωt e
jβ
.
Since all operations have a linear character, then a functional operator describing
the real part of a complex number, Re, is dropped in formulation, and instead of
(3.23), expression (3.24) is as follows:
S(t) = A(t)e
jωt e
jϕ(t)
,
(3.24)
With such an approach, we can firmly assert both on amplitude and phase of
examined signals.
29
3.3 Radar Targets Scattering Matrix
As it was mentioned above, one of the main tasks of radar location concludes in
conducting of classification of detected target, i.e., in determining of its reflecting
characteristics, dimensions, configuration and spatial orientation.
Radar location can be examined as a tool of remote sensing of radar targets,
which can be any research objects including sea and aerial vessels, unmanned aerial
vehicles (UAVs), space vehicles, and ground surface and hydrometeorologicals. An
information carrier on radar targets is a scattered electromagnetic wave registered by
a receiving radar device integrated in a radar station (radar). At any processing technique of radar signals, the desired information can be retrieved and then interpreted
only via comparison of transmitted and received electromagnetic waves.
During solving of air traffic control (ATC) tasks, the radar and targets in the most
cases are located on a quite far distance from each other that permits to consider
incident wave in neighborhood of a target and scattered near an antenna—as a
flat one—which can be described using only one electric vector E. Limiting by
a case of single-position radar location, when receiving and transmitting antennas
are combined in a space that is specific to ATC radar, finally, the problem of data
acquisition on radar targets leads to comparison of electric vector of radiated E rad
and received E rcv electromagnetic waves of an antenna.
At such comparison, the essential role is for range from a radar to a target, D,
which is easily considered; based on that, radiation field falls as 1/D; accordingly for
the purpose to avoid overloading of resulting relations, a field scattered by a target
in direction to a target (reflected wave) can interpret as E rcv .
In radar location, as it will be explained in detail further, in the most cases, the
narrow-band signals S(t) are used, for which, according to Hilbert, the following
representation is admitted:
S(t) = A(t) cos(ωt + ϕ(t) + ϕ 0 ),
(3.23)
where A(t) and ϕ(t) are some slowly varying functions per high frequency period T
= 2π /ω, ϕ 0 is initial phase, which at this review does not play an important role;
consequently, we will read it as ϕ 0 = 0.
In teaching materials on radio-engineering, particular on radar location, it often
uses its formulation in a complex form instead of (3.23) representation relying on
the fact that: A cos(ωt + β) = Re
Ae
jωt e
jβ
.
Since all operations have a linear character, then a functional operator describing
the real part of a complex number, Re, is dropped in formulation, and instead of
(3.23), expression (3.24) is as follows:
S(t) = A(t)e
jωt e
jϕ(t)
,
(3.24)
With such an approach, we can firmly assert both on amplitude and phase of
examined signals.