Salisbury screen

Two of the oldest and simplest types of absorbers are represented by Salisbury screens and Dallenbach layers. The Salisbury screen is a resonant absorber created by placing a resistive sheet on a low dielectric constant spacer in front of a metal plate. The Dallenbach layer consists of a homogeneous lossy layer backed by a... 

The bandwidth of a Salisbury screen can be improved by adding additional resistive sheets and spacers to form a Jaumann absorber. To provide... 

Potential applications of the electromagnetic properties of polyaniline have been discussed [81-83], New polymers such as poly-/j-phenylene-benzobis-thiazole [20] have also been investigated. Tuning at 9 and 10 GHz has been obtained with this class of material. Double and single-layer Salisbury screens using PBT vrere fabricated [19]. An absorption of 90% was... 

The results obtained are supposed to make possible a choice between different materials in agreement with the requested concept for the manufacturing of microwave absorbing materials. For instance, in the case of a Salisbury screen (resistive layer of 377 Q/D), it is better to use materials with a low e, lower than e". While, in the case of a Dallenbach screen, the best solution would be a high f/, higher than f". 

Finally, direct electrochemical growth at the surface of a honeycomb placed onto the electrode can produce, in one step, a Salisbury screen [180] since the conductivity through this process is controlled with a homogeneity of 5% [167]. 

Smart skins are to be considered in the context of radar absorbing materials where solutions have been given in [113,114]. Smart microwave windows have been proposed in the context of using poly(aniline)-silver-polymer electrolyte composite materials which have shown a change in microwave reflectivity when a small electrical dc potential is applied among them [115]. An adaptive radar absorbing structure based on the topology of a Salisbury screen combined with an active frequency selective surface controlled by PIN diodes has been described in [116] which allows for superior reflectivity-bandwidth. 

Chambers and coworkers [72-74] also explored the properties of semiconductive sheets of polypyrrole treated paper and cloth, which they characterize as a parallel RC circuit. They too report that the capacitive part of the complex impedance of the sheets depends on the morphology of the poly pyrrole coating. Measured reflectivity plots for Salisbury screen (narrowband) and Jaumann (broadband) absorbers fabricated from sheets of polypyrrole-treated material are also presented in their article. The measured results agree well with their model calculations, indicating the potential utility of conductive polymer-treated fabrics in radar-absorbing structures. 

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