| dc.description |
Embedded below the radome of a missile, existing RF-seekers use a mechanical
rotating antenna to steer the radiating beam in the direction of a target. Latest research
is looking at replacing the mechanical antenna components of the RF seeker with a
novel 3D conformal antenna array that can steer the beam electronically. 3D antennas
may oer signicant advantages, such as faster beamsteering and better coverage but, at
the same time, introduce new challenges resulting from a much more complex radiation
pattern than that of 2D antennas. Thanks to the mechanical system removal, the new RF-seeker has a wider available space for the design of a new 3D conformal antenna. To take best benets of this
space, dierent array shapes are studied, hence the impact of the position, orientation
and conformation of the elements is assessed on the antenna performance in terms of
directivity, ellipticity and polarisation. To facilitate this study of 3D conformal arrays,
a Matlab program has been developed to compute the polarisation pattern of a given
array in all directions. One of the task of the RF-seeker consists in estimating the position of a given target
to correct the missile trajectory accordingly. Thus, the impact of the array shape on
the error between the measured direction of arrival of the target echo and its true
value is addressed. The Cramer-Rao lower bound is used to evaluate the theoretical
minimum error. The model assumes that each element receives independently and
allows therefore to analyse the potential of active 3D conformal arrays. Finally, the
phase monopulse estimator is studied for 3D conformal arrays whose quadrants do
not have the same characteristics. A new estimator more adapted to non-identical
quadrants is also proposed. |
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