Qinetiq Limited

Peter Allen Hobson

Christopher Robert Lawrence

John Roy Sambles

Shahid Hussain

Alastair Paul Hibbins

Philip Mark Shryane Roberts

Matthew J Lockyear

Shahaid Hussain

A radiation absorber comprising multiple layers has a conducting base layer, and at least first and second further layers, each separated by a dielectric material, the first and second layers having patches thereon of highly conducting material, and defining resonant cavities in cooperation with the dielectric material, wherein the resonant cavities formed on adjacent layers differ in frequency. Characteristics of the patch, such as size or shape may vary on each layer to provide different resonant frequencies, and/or dielectric or magnetic properties of the dielectric material, and/or separation distance of the patches may be varied. In some embodiments, complex dielectrics may have their loss factors adapted to tune a resonant frequency, or to adapt its resonant bandwidth.

Electromagnetic radiation absorber

A composite material comprises magnetic particles dispersed in electrically insulating material. The magnetic particles have an aspect ratio greater than 1 (preferably greater than 10) and a concentration sufficiently high to produce negative permeability. The magnetic particles may be magnetic flakes of reduced carbonyl iron of average diameter 50 &#x3bc;m, average thickness 1 &#x3bc;m and aspect ratio 50, the magnetic flakes being at least 25% by volume of the composite material. The magnetic flakes may be aligned to produce enhanced permeability. The electrically insulating material may be paraffin wax, particulate PTFE, or another polymer. To control permittivity, the composite material may include an electrically conducting component such as graphite or conductive coatings upon the magnetic flakes.

Composite material

Growing community of inventors

Malvern, United Kingdom

Peter Allen Hobson