A magnetic composite includes a polymeric substrate and a magnetic material including a Z-type phase and represented by the following Chemical Formula:

Ba.sub.1.5-xSr.sub.1.5-xCa.sub.2xM.sub.2Fe.sub.24O.sub.41  Chemical Formula

wherein, in the Chemical Formula, M is at least one selected from Co, Ni, Cu, Mg, Mn, Ti, Al, Zn, and Zr, and 0≦x<0.3.

The present invention relates to an electromagnetic millimetre wave transmission reducing material, preferably having a volume resistivity of more than 1 Ωcm, containing particles of at least an electrically conductive, magnetic or dielectric material and an electrically non-conductive polymer, wherein the transmission reducing material is capable of reducing transmission of electromagnetic waves in a frequency region of 60 GHz or more. The invention also relates to its use and method for reducing transmission as well as an electronic device comprising said transmission reducing material.

The disclosure aims at providing an antenna array for 5G communications that has superior thermal dissipation and crosstalk suppression effect. To achieve the above-described object, an antenna array 1 for 5G communications according to the disclosure includes a substrate 10; at least one high-frequency semiconductor device 20, a noise-suppressing thermally conductive sheet 20, and a first thermal dissipation member 41 sequentially formed on one surface 10a of the substrate 10; and at least one antenna 50 and a second thermal dissipation member 42 sequentially formed on the other surface 10b of the substrate 10.

Embodiments provide a radio frequency apparatus including a radome, an absorber, and a radio frequency circuit board that may be used for millimeter wave radar of an intelligent automobile to reduce high-frequency radiation interference from a radio frequency chip and an antenna feeder.

There is provided a radio wave absorbing composition containing a magnetic powder and a binder. There is also provided a radio wave absorber containing a magnetic powder and a binder. The magnetic powder is a powder of a substitution-type hexagonal ferrite subjected to surface treatment with a surface treatment agent, the surface treatment agent is a silicon-based compound, and the binder is an olefin-based resin.

A method for producing a layer of a device for electromagnetic radiation absorption, includes: providing a ply of powder material in the layer to be produced of the device; providing a predefined concentration distribution of particles for electromagnetic radiation absorption in the layer; providing a first binder and a second binder for the powder materials, wherein the first binder includes particles for the absorption of electromagnetic radiation, wherein the second binder includes a lower concentration of identical and/or different particles than the first binder; determining a mixing ratio between the first binder and the second binder for every position in the layer; selecting a position of the layer; mixing the first and second binder according to the mixing ratio for the selected position; wetting the powder material at the selected position using the mixed first and second binders; and repeating selecting, mixing, and wetting to produce the layer.

A circuit substrate includes a multi-layer substrate in which a plurality of dielectric layers are stacked, and a millimeter wave absorber provided inside the multi-layer substrate and having an electromagnetic wave absorption peak within a region of 30 to 300 GHz. An antenna element includes the circuit substrate described above, a power feeder provided inside the multi-layer substrate of the circuit substrate, and an antenna provided on a surface of the circuit substrate and connected to the power feeder. A method for reducing noise in a circuit substrate including a multi-layer substrate includes, by a millimeter wave absorber provided inside the multi-layer substrate and having an electromagnetic wave absorption peak within a region of 30 to 300 GHz, absorbing unnecessary electromagnetic waves diffused in the multi-layer substrate to reduce noise in the circuit substrate.

For the purpose of providing an electromagnetic wave absorber usable for radar having a high resolution and sufficiently adaptable to a plurality of radars different in frequency, the bandwidth of a frequency band in which an electromagnetic wave absorption amount is not less than 20 dB is not less than 2 GHz, within a frequency band of 60 to 90 GHz.

Embodiments disclosed herein relate to using cobalt (Co) to fine tune the magnetic properties, such as permeability and magnetic loss, of nickel-zinc ferrites to improve the material performance in electronic applications. The method comprises replacing nickel (Ni) with sufficient Co.sup.+2 such that the relaxation peak associated with the Co.sup.+2 substitution and the relaxation peak associated with the nickel to zinc (Ni/Zn) ratio are into near coincidence. When the relaxation peaks overlap, the material permeability can be substantially maximized and magnetic loss substantially minimized. The resulting materials are useful and provide superior performance particularly for devices operating at the 13.56 MHz ISM band.

An electromagnetic wave absorbing thermally conductive composition contains a matrix resin component, metal soft magnetic particles, and thermally conductive particles. The metal soft magnetic particles are carbonyl iron particles and are present in an amount of 30% by volume or more when the electromagnetic wave absorbing thermally conductive composition is a population parameter. A value of an imaginary part (μ″) of relative permeability of the electromagnetic wave absorbing thermally conductive composition is 0.9 or more in at least some bands in a frequency range of 18 to 26.5 GHz. The electromagnetic wave absorbing thermally conductive composition in the form of a sheet has a thermal conductivity of 2.0 W/m.Math.K or more in the thickness direction. A sheet of the present invention incudes the above composition in the form of a sheet. Thus, the present invention provides the electromagnetic wave absorbing thermally conductive composition and its sheet that can increase the value of the imaginary part (μ″) of relative permeability in a frequency band of 18 to 26.5 GHz, efficiently absorb electromagnetic wave noise in this frequency band, and also have a high thermal conductivity.