44results about How to "Increased absorption bandwidth" patented technology

For the purpose of providing an electromagnetic wave absorber usable for radar having a high revolution 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.

The invention discloses a wave-absorbing and anti-electromagnetic radiation clothing, which includes a clothing body; the clothing body includes a moisture-absorbing and sweat-wicking layer, an electromagnetic wave shielding layer, an electromagnetic wave absorbing layer, and a waterproof and breathable layer; The contact area of ​​the electromagnetic wave shielding layer is set in a waveform, which can better shield the electromagnetic wave and reflect it to the electromagnetic wave absorbing layer for second absorption; the specific surface area of ​​the nano-silicon oxide in the wave-absorbing chemical fiber increases, and the grain boundaries and grain boundary atoms The number of dangling bonds increases, and the loss of incident electromagnetic waves increases. Acetylene carbon black can reduce the minimum reflectivity of nano-silicon oxide, expand the absorption bandwidth, and increase the anti-electromagnetic radiation effect; zinc ferrite has the effect of absorbing electromagnetic waves, and expanded perlite The dielectric constant is close to that of air, which can better match the impedance between the surface of the material and the free space, reduce the reflectivity of the surface of the material, allow electromagnetic waves to enter the interior of the material, and give full play to the wave-absorbing performance of zinc ferrite.

The invention provides a microwave absorber composite material capable of achieving full frequency band absorption within the range of 2-8 GHz.The microwave absorber composite material is formed by superimposing three base body units formed by covering rectangular micro-structure materials with microwave absorption materials, the rectangular micro-structure materials are formed in the mode that the two faces of inorganic non-metal plates are symmetrically covered with multiple rectangular metal sheets in sequence to form matrixes, the thicknesses of the rectangular metal sheets in the rectangular micro-structure materials in the base body units are the same, but the lengths or widths of the rectangular metal sheets are sequentially increased; a microwave absorption material coating is formed on the upper side face of the rectangular micro-structure material of the base body unit on the uppermost layer, wherein the thickness value of the microwave absorption material coating is larger than that of a microwave absorption material coating of the base body unit, and a supporting plate is coated with a microwave absorption material coating of the base body unit on the lowest layer.According to the material, under the condition that overall thickness is slightly increased, the microwave absorption frequency band is moved in the low frequency direction by controlling the sizes of the three rectangular micro-structure materials, absorption bandwidth is greatly increased, reflection losses within the frequency range of 2-8 GHz are lower than -10 dB, and full frequency band absorption is truly achieved.

The invention discloses a preparation method of a honeycomb sandwich composite material, which belongs to the technical field of aerospace material preparation, and is characterized in that it comprises the following steps: a. preparing an impregnating solution; b. placing a rectangular cross-section honeycomb core in an impregnating tank c. Prepare impregnating solution 2; d. Put trapezoidal cross-section honeycomb core 2 in the dipping tank and fully impregnate; e. Use adhesive film to bond rectangular cross-section honeycomb core 1 and trapezoidal cross-section honeycomb core 2 together to obtain Composite honeycomb core; f, bonding the upper panel on the upper surface of the composite honeycomb core, bonding the lower panel on the lower surface of the composite honeycomb core, and finally solidifying and cooling to room temperature to obtain a honeycomb sandwich composite material. The invention obtains two types of honeycomb cores containing different absorber coatings by wet impregnation, and obtains a composite honeycomb sandwich structure through reasonable design, and then glues and solidifies it with the panel, which can effectively improve the wave absorption of the entire honeycomb sandwich composite material Bandwidth, enhance the absorption effect of electromagnetic waves.

A heating apparatus using an electromagnetic wave is disclosed, by which a capacity of a cavity is increased and by which cut-off performance of the electromagnetic wave and facilitation of door cleaning can be enhanced. The present invention includes a door provided to an open front side of a body to be opened / closed, a choke filter having a panel type choke part arranged by at least one or more rows along an edge of the door and a filter part having a plurality of slots wherein a prescribed choke part is provided to a most outer side, and a glass panel attached to an inner lateral side of the door and the choke filter.

The invention discloses a graphene aerogel and a preparation method and an application thereof, wherein the aerogel is prepared from the following method: (1) pre-reduction treatment: adding a reducing agent to a graphene oxide solution, mixing, carrying out ultrasonic dispersion, and carrying out pre-reduction treatment, to obtain a semi-reduction graphene hydrogel; (2) final reduction treatment:adding a reducing agent, carrying out ultrasonic treatment, and then carrying out final reduction treatment, to obtain a graphene hydrogel; and (3) acid / alkali soaking: placing the graphene hydrogelin an acid or alkali aqueous solution, soaking, washing the hydrogel to be neutral, sucking out the excess liquid, and carrying out freeze drying, to obtain the graphene aerogel. The graphene aerogelis applied to electromagnetic wave absorption materials. The graphene aerogel obtained by the method has small density and good integrality, and has a certain mechanical strength and resillency; the prepared wave absorbing material has good electromagnetic wave absorption performance, and the wave absorbing performance can be adjusted; and the method has the advantages of simple process, short production cycle, low cost and good benefits, and is suitable for industrialized production.