Phase modulating microwave structures

Conventional approaches to controlling the electromagnetic scattering from an object usually rely on either modifying its shape and/or coating its surface with lossy materials. In the former approach, the scattered energy is redirected to regions of space that are outside the angular detection range of receiver systems, whilst in the latter case incident energy is absorbed and converted into heat.

In a new approach to this problem, we are investigating techniques by which the energy scattered from an object is translated in the frequency domain to regions which are outside the bandwidth of detection systems. This is achieved by imposing phase modulation on the scattered signal using an active surface – the phase switched screen. By this means, planar and conformable surfaces may be realised which can exhibit controllable scattering characteristics over a wide frequency range.

Prototype phase modulating screen