Electromagnetic wave absorber for VHF to UHF band
AssigneeNEC Corporation
InventorKenichi Hatakeyama
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Abstract
An electromagnetic wave absorber available for a VHF to UHF band is implemented by a conductive film, a magnetic film laminated on the conductive film and back-plated with a metal film, and the magnetic film is formed from a resin film containing ferrite powder equal to or greater than 70% by weight so that the electromagnetic wave absorber is flexible and available for a large and wide structure.
Claims14
An electromagnetic wave absorber for electromagnetic waves in the very high frequency to ultra high frequency band, comprising:
- a) a first conductive film structure having a surface and having a first capacitive reactance and a loss factor;
- b) a magnetic film comprising a resin film containing ferrite ceramic particles laminated on the surface of said first conductive film structure and having an inductive reactance and a loss factor, the capacitive reactance and the loss factor of said first conductive film and the inductive reactance and the loss factor of said magnetic film forming a resonant circuit which is matched with a characteristic impedance of a space occupied by said first conductive film and said magnetic film when the resonant circuit is in the resonant condition;
- and
- c) a second conductive film laminated on the opposite surface of said magnetic film to the surface attached to said first conductive film structure, and having reflecting characteristics substantially equivalent to metal.
An electromagnetic wave absorber for electromagnetic waves in the very high frequency to ultra high frequency band, comprising:
- a first conductive film structure comprising a single conductive film selected from a resin containing carbon particles, a conductive substance containing conductive metal powder of copper, nickel, aluminum or iron, a conductive substance containing a conductive alloy, a conductive substance containing conductive metal fibers and a conductive substance containing carbon fibers;
- a magnetic film comprising a resin fil laminated on the surface of said first conductive film structure, said magnetic film having a thickness ranging from about 3 millimeters to about 50 millimeters;
- ferrite ceramic particles embedded in the resin film and selected from a group consisting of Ni-Zn alloy Mn-Zn alloy, said ferrite ceramic particles having a grain size of between about 0.1 millimeters to 3 millimeters;
- a second conductive film laminated on the opposite surface of said magnetic film to the surface attached to said first conductive film structure, and having reflecting characteristics substantially equivalent to metal.
An electromagnetic wave absorber for electromagnetic waves in the very high frequency to ultra high frequency band, comprising:
- a first conductive film structure comprising a first conductive film member laminated to a second conductive film member;
- a magnetic film comprising a resin film laminated on a surface of said first conductive film structure, said magnetic film having a thickness ranging from about 3 millimeters to about 50 millimeters;
- ferrite ceramic particles embedded in the resin film and selected from a group consisting of Ni-Zn alloy and Mn-Zn alloy, said ferrite ceramic particles having a grain size of between about 0.1 millimeters to 3 millimeters;
- a second conductive film structure laminated on the opposite surface of said magnetic film to the surface attached to said first conductive film structure, and having reflecting characteristics substantially equivalent to metal.
An electromagnetic wave absorber for electromagnetic waves in the very high frequency to ultra high frequency band, comprising:
- a first conductive film structure having first and second surfaces;
- a magnetic film comprising a resin film free from metallic fiber for maintaining a high input impedance, said magnetic film being laminated on the first surface of said first conductive film structure;
- a plurality of ferrite ceramic particles embedded in the resin film;
- a second conductive film laminated on the second surface of said magnetic film, said second conductive film having reflecting characteristics substantially equivalent to metal and said first conductive film structure, said magnetic film and said second conductive film forming a resonant circuit for absorbing electromagnetic waves.
Dependencies are inferred from the claim text.