Microwave absorber

A microwave absorber consisting essentially of a mixture of from 0.2 to 0.9 part by volume of a ferrite powder and from 0.8 to 0.1 part by volume of an organic high molecular compound, said ferrite powder being a powder having a particle size of less than 1.65 mm of a ferrite having the general formula MFe.sub.2 O.sub.4 in which M is selected from the group consisting of manganese, nickel, copper, zinc, magnesium and cobalt and having an initial permeability of more than 300 at 10 kHz, said organic high molecular compound being a thermosetting resin selected from the group consisting of phenol resin, polyester resin, epoxy resin and silicone resin;

• or a thermoplastic resin selected from the group consisting of polyvinyl chloride, polyethylene and polypropylene;
• or a natural and synthetic rubber selected from the group consisting of polychloroprene, acrylonitrile-butadiene-styrene and fluorine-contained rubber, said ferrite powder in a certain particle size range being used for absorbing the microwave in a certain frequency range as shown below:
• ______________________________________ Particle size of ferrite Frequency of powder microwave ______________________________________ 1.65 mm - 701 .mu. 500 MHz - 1.5 GHz 701 .mu. - 351 .mu. 1.0 GHz - 2.0 GHz 351 .mu. - 104 .mu. 1.8 GHz - 3.0 GHz 104 .mu. - 43 .mu. 2.5 GHz - 7.5 GHz <43 .mu. 6.0 GHz - 12.0 GHz. ______________________________________