Improvements in or relating to microwave devices

The invention relates to a microwave reflecting, refracting or guiding device such as a waveguide, or an aerial reflector or lens, consisting of a supporting member of light weight insulating material such as fibreglass and adherent thereto a layer formed of metal flakes or filings in cured resinous material in which the flakes or filings are suspended before curing. A method of making the device consists of mixing the flakes or filings which may be copper, brass, iron or steel in a curable resinous material in fluid form such as epoxy resin and/or polyester resin, applying the mixture to a former of predetermined shape to form a layer thereon, curing the resinous material and, before completion of the curing, laying insulating backing material on to the exposed surface of the layer of the mixture to provide a mechanically supporting backing, the completed device then being separated from the former. The surface of the metal/resin layer remote from the insulating material may be provided with a final coating deposit of conductive material. The metal flakes or filings may be provided with contacts through which a heating current may be passed for de-icing the device.