Single-layer reactive impedance PSS

The phase switched screen (PSS) is a technique that can be used to provide ´real-time´ dynamic control of the radar cross section of an object. Conventional, passive radar absorbing materials operate either on the principle of phase cancellation, such as a Salisbury screen, or use lossy materials to absorb incident electromagnetic energy, as in a Dallenbach layer. In the PSS approach however, the energy scattered by an object is translated in the frequency domain to regions that are outside the bandwidth of detection systems. The PSS achieves this translation in frequency by imposing phase modulation onto the energy scattered from the object to produce a signal with a low time-average energy spectral density. In previous publications we have demonstrated both theoretically and experimentally that a resistively switched PSS has similar reflectivity characteristics to that obtained from a Salisbury screen. Larger operating bandwidths and tuneable PSS absorbers can be realised by using two or more active layers, but at the expense of increased absorber thickness. We describe how a single-layer PSS based on reactive impedance switching can be used to provide a significant increase in reflectivity bandwidth performance, and also a reduction in absorber thickness without using high permittivity materials.