Salisbury screens are used to reduce back-scattering from flat perfect electrically conducting (PEC) plates. A resistive sheet having a resistivity close to that of free space (377 Ohm) is placed roughly one quarter of a wavelength in front of the conducting plate. Due to the spacing requirement, this is a narrow-band technique. In  the design parameters (resistivity and spacing) are optimized for minimum radar cross section.
Figure 1 shows the simulation model used to determine the RCS for the Salisbury screen and PEC plate.
|Figure 1: Simulation model of Salisbury screen|
The bistatic RCS of a PEC plate is compared to that obtained with the use of a Salisbury screen in Figure 2. Both the Salisbury screen and PEC plate are square with side lengths equal to 4 wavelengths and a normally incident plane wave is used to illuminate the screen / plate. Clearly scattering is reduced significantly with the use of the Salisbury screen, especially for angles near the angle of incidence (theta = 0).
|Figure 2: Bistatic RCS for normal incident plane wave on Salisbury screen
Monostatic RCSs of Salisbury screens / PEC plates of different sizes are compared in Figure 3. Again a normally incident plane wave is used to illuminate the target. As expected the RCS of a certain size Salisbury screen is much smaller than that of an equally sized PEC plate. The oscillatory behaviour in the RCS of the Salisbury screen is ascribed to edge current effects in .
|Figure 3: Monostatic RCSs of different sized Salisbury screens|
|||R.L. Haupt, "Scattering from Small Salisbury Screens", IEEE Transactions on Antennas and Propagation, Vol. 54, No. 6, June 2006.