Abstract: Device for estimating, at high temperature, the electromagnetic properties of a material, including:an oven (1, 19, 20);a waveguide (3) disposed at least in part in said oven, a housing for a specimen piece of uniform thickness made of said material, this specimen piece being such that, when it is disposed in said housing, its outer periphery matches the inner surface of the waveguide;means (4, 5, 6) for applying an incident very high frequency electromagnetic wave to the waveguide (3); andmeans (4, 5, 6) for collecting the electromagnetic wave reflected by said specimen piece.A vertically disposed waveguide has (3) said housing provided at the open lower end (3B ).

Abstract: In order to measure the electromagnetic characteristics of a moving filiform material without cutting the latter and without any risk of a liquid and/or solid pollution introduced by the material disturbing the measurements, an ultra-high frequency cavity (10) is proposed, whose wall (12) is traversed by two facing orifices, in which are placed the two open parts of a dismantlable tubular protective device (26). The slot (24) makes it possible to introduce the filiform material (F) in to the cavity. The device (26) isolates the filiform material from the latter and its production in two parts enables it to be put into place without cutting the material. The protective device (26) is replaced without stopping the measurements and without any pollution being able to enter the cavity.