Recent developments in radar navigation and remote sensing have led to a requirement for
rugged yet inexpensive location markers and calibration targets which present both a very large
scattering cross section and a specified polarization response over a wide angular range. This
study considers several problems related to the analysis and design of passive radar targets
derived from corner reflectors.
Transformation of the polarization response of a target between global and local coordinate
frames is shown to correspond to rotation of the polarization basis by a prescribed angle which is
a function of both the coordinate transformation matrix and the direction of propagation. Once
the angle of rotation has been determined using either spherical trigonometry or vector algebra,
any polarization descriptor can be transformed between coordinate frames by application of a
suitable rotation operator.
The scattering cross section and angular coverage of a conventional trihedral corner reflector
can be altered by modifying the size and shape of its reflecting panels. A numerical algorithm
based on physical optics is used to predict the contribution of triple-bounce reflections to the
response of a reflector with polygonal panels of arbitrary shape. If three-fold symmetry is
broken and the reflector is simply required to present bilateral symmetry, it is found that the
scattering cross section, elevation beamwidth, and azimuthal beamwidth of the reflector can be
chosen independently of each other.
A method for altering the polarization response of a conventional trihedral corner reflector
by adding conducting fins or corrugations to one its interior surfaces is proposed. In calculating
design curves for twist-polarizing or circularly polarizing reflectors by mode-matching, optimum accuracy and efficiency are obtained by setting the ratio of free space to groove modes
equal to the ratio of groove width to the period. Methods for obtaining linear and circular
polarization selective responses are considered. The contribution of triple-bounce reflections to
the response of such reflectors is a function of the direction of incidence, the orientation of the
reflector, the dimensions of the corrugations, and the size and shape of the reflecting panels.
Experimental results show that prototype twist-polarizing and circularly polarizing reflectors
respond essentially as predicted.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/7038 |
| Date | 05 1900 |
| Creators | Michelson, David George |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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