The phase-switched screen

Abstract

Conventional (passive) radar-absorbent materials operate either by phase cancellation or by absorbing incident electromagnetic energy and converting it into heat. This paper examines a new type of active "absorber," called the phaseswitched screen (PSS). The PSS operates quite differently from passive absorbers in that it exhibits an apparently low value of reflectivity by redistributing the electromagnetic energy incident upon it over a bandwidth that is wide enough to ensure that little reflected energy falls within the pass-band of the receiver. The discussion considers the basic temporal and spectral properties of several PSS topologies, and includes measured data on both planar and cylindrical PSS structures.

Effect of element failure in active coatings for wind turbine generator blades

“…In the limit, N FAILED = 50%, optimum reflectivity can be obtained with τ/T = 1.0 (remaining elements turned 'on' all the time). This behaviour is exactly equivalent to the phase-switched screen [1]. Conversely, if τ/T = 0 (all elements remain 'off' all the time), the panel reflectivity is identical to that of a PEC layer, as expected.…”

“…As a part of a larger programme, therefore, we have investigated the feasibility of using active coatings on the WTG blades which might either reduce unwanted reflections by spreading them in the spectral, temporal or spatial domains or label them so that they might be identified and removed in the radar signal processing [1], [2]. In practice, the total surface area of the blades on each WTG will be several hundred m 2 and even if this whole area does not need treatment, it still implies very large scale application of active surfaces.…”

Secure electromagnetic buildings

“…The signal is transmitted through a surface with a transmission coefficient magnitude of 1 and the transmission phase is varying from ±60° at a switching frequency of 270kHz. The response shown in Fig.2 is similar to that of a Phase Switched Screen (PSS), [11]. The switching process shifts the energy at the carrier frequency to the sidebands, the frequency of the sidebands are odd multiples of the switching frequency.…”

The Optimization of Switching Scheme in Multi-Layer Phase-Modulated Surface and Its Influence on Scattering Properties

“…In [4], Tennant and Chambers from the UK's University of Sheffield designed phase-modulated surface (PMS), which is composed of single AFSS layer and one mental background plane. In [5][6][7], the transmission line theory was used to analyze the PMS, and results demonstrated that the regulation in switching scheme of AFSS layer would lead to the variation in scattering characteristic of PMS. In [8,9],and the switching scheme of AFSS are both associated with the absorbing performance of PMS.…”