Corner reflectors

In the case where the number of possible measurements, that can be made, is noticeably reduced due to the absence of radar targets with PS characteristics, it is possible to install some specific artificial reflectors that act as basis radar benchmarks.
Reflectors are made of metal and, once installed, require negligible maintenance. Their reflectivity is so strong that they are easily identified by the satellite's sensors, after their installations.

Up to date three types of artificial reflectors have been used in PS analysis:

Planar A single square plate of about 120 cm, that is more suitable for urban settings, because of its reduced environmental impact.

Dihedral The type made of two square plates, with sides measuring 100 cm.

Trihedral An empty trihedron with sides of 170 cm, suitable for non urban settings. The corner type has a triangle base.