11results about How to "Reduce Impedance Mismatch" patented technology

The invention relates to the technical field of electric connectors, in particular to a feed-through connector which comprises a feed-through insertion piece, a coaxial cable, a coaxial connector with the characteristic impedance of 50 ohms, an epoxy resin sealing layer and a connecting plug. The feed-through insertion piece is made of an insulating high-molecular polymer material and comprises an installation body, the installation body is provided with a first side and a second side which are oppositely arranged in the axial direction, an installation channel penetrating in the axial direction is formed in the installation body, and a plurality of bolt holes are formed in the installation body; the mounting channel comprises a first hole section and a second hole section which are sequentially communicated in the axial direction, the hole diameter of the first hole section is larger than that of the second hole section, and the connecting plug is fixedly arranged on the first side of the mounting body and coaxially and correspondingly arranged with the mounting channel; and stable coaxial transmission and sealing insulation effects can be realized while the mechanical connection reliability is maintained.

The embodiment of the invention provides a preparation method of an electromagnetic wave absorbent and the electromagnetic wave absorbent. The polymethyl methacrylate dispersion liquid and the MXene colloidal solution are mixed and then stirred to obtain a first precipitate, and the first precipitate is dried to obtain first mixed powder; dispersing the first mixed powder in a first solvent to obtain a first dispersion liquid; cobalt salt is dispersed in a second solvent, and second dispersion liquid is obtained; dispersing the MOFs organic ligand in a third solvent to obtain a third dispersion liquid; mixing the first dispersion liquid and the second dispersion liquid, then mixing and stirring with the third dispersion liquid to obtain a second precipitate, and drying the second precipitate to obtain the composite material. And carbonizing the composite material to obtain the electromagnetic wave absorbent with the hollow heterostructure. According to the prepared electromagnetic wave absorbent, impedance mismatch is reduced, the loss form of the electromagnetic wave absorbent is enriched, and the wave absorbing performance of the electromagnetic wave absorbent is enhanced.

The present invention discloses a terahertz antenna integrated with a high-temperature superconducting high-order in-phase series mixer, comprising a terahertz antenna; the terahertz antenna comprises a butterfly metal layer at both ends; a plurality of low-impedance mixers are embedded between the butterfly metal layers at both ends; and the plurality of low-impedance mixers are connected by a meandering metal layer. The present invention is to design a terahertz antenna with low input impedance with multi-source excitation, and embed a high-order in-phase series low-impedance mixer in the terahertz antenna to complete impedance matching without affecting antenna performance; the butterfly-loaded meandering antenna can embed a plurality of low-impedance mixers in the meandering line to complete impedance matching without affecting antenna performance; the length of the meandering line between the mixers can be arbitrarily adjusted to adjust the active impedance and complete the matching with the mixer impedance; the embedded low-impedance mixer can be increased or decreased according to the needs of actual applications, and the impedance matching between the antenna and the mixer is improved, thereby increasing the harmonic order and reducing the impedance mismatch.

The invention discloses a preparation method of an electromagnetic wave absorbent and the electromagnetic wave absorbent, and the preparation method of the electromagnetic wave absorbent comprises the following steps: obtaining raw materials including acrylic acid, polyvinyl alcohol and MXene powder, and preparing MXene porous aerogel based on the raw materials; preparing a hollow CoS nanosphere; carrying out modification treatment on the hollow CoS nanospheres; and combining the MXene porous aerogel with the hollow CoS nanospheres subjected to the modification treatment, so as to prepare the light three-dimensional porous wave-absorbing aerogel. The porous structure of the aerogel and the hollow structure of the hollow CoS nanosphere can cooperate with each other, and after cooperation, the impedance of the aerogel and the hollow structure of the hollow CoS nanosphere is close to that of a free space, so that impedance mismatch can be reduced, and magnetic loss of electromagnetic waves can be well carried out.

The utility model belongs to the technical field of noninvasive medical treatment, and particularly relates to a treatment bed and nuclear magnetic resonance equipment. The treatment bed comprises a bed body, a treatment probe and an anti-interference device, wherein the bed body is used for bearing a patient; the treatment probe is arranged in the bed body and can move to the wounded part of the patient; the anti-interference device is arranged on the bed body, the geometric center of the anti-interference device coincides with the geometric center of the treatment probe, and the anti-interference device can generate an induced magnetic field. The direction of an induced magnetic field formed by the anti-interference device is opposite to that of a magnetic field generated by the nuclear magnetic resonance equipment, and the induced magnetic field can hinder the magnetic flux change when the magnetic field generated by the nuclear magnetic resonance equipment penetrates through the anti-interference device, so that the energy of an electromagnetic field of the magnetic field generated by the nuclear magnetic resonance equipment in the scanning process is reduced; the impedance mismatch of the load end of the body coil of the nuclear magnetic resonance equipment is reduced, and the scanning success rate of the nuclear magnetic resonance equipment is improved.

The invention relates to a feed network and a directional diagram shaped antenna. The feed network is arc-shaped, a plurality of power dividers are arranged on the arc-shaped structure at equal intervals, and the power dividers are connected through phase shift transmission lines; a plurality of metal columns are further arranged near the circle center of the arc-shaped structure, and the metal columns are annularly arranged at equal intervals; the power dividers are connected with the metal columns through impedance conversion transmission lines for signal transmission. The feed network is good in symmetry, isolation resistance can be reduced, and transmission loss can be reduced.

The application relates to the technical field of ultrasonic nondestructive testing, and provides a superhigh-temperature piezoelectric sheet dry-coupling ultrasonic detection device and a detection method, which comprises a conductive base, a top pressing assembly which is arranged above the conductive base in a liftable mode, and a multilayer detection unit which is arranged between the top pressing assembly and a workpiece to be detected; the multilayer detection unit is sequentially stacked from top to bottom as follows: a high-temperature-resistant insulating layer, a conductive pressing sheet, an upper dry-coupling sheet, a piezoelectric sheet and a lower dry-coupling sheet; the conductive pressing sheet is electrically connected with a first signal lead-out wire, the conductive base is electrically connected with a second signal lead-out wire, and the first signal lead-out wire and the second signal lead-out wire are both used for connecting an external information processing unit. Through the technical scheme, the technical problem that there is no technical scheme capable of realizing continuous and stable ultrasonic detection through stable coupling and reliable structural design in an overall superhigh-temperature environment is solved.

The utility model discloses a K waveband wave same conversion structure relates to microwave communication and radar technical field. The K waveband wave same conversion structure includes integrated metal - dielectric composite cavity, and the cavity has the top cover plate, the intermediate layer and the bottom plate, the top cover plate inlay ceramic sheet array of dielectric constant gradient, the intermediate layer includes the metal grid of suspension gradient, and the grid density is increasing along the propagation direction, and the bottom plate is provided as the metal reflection plate of the bellowed convex projection. The K waveband wave same conversion structure provided by the utility model is used for solving the narrow bandwidth, high loss and volume limit problem in the prior art.

A preparation method of a glass fiber / graphene oxide / metal electromagnetic shielding composite material, comprising the following steps: S1: repeatedly centrifuging and washing an oxide graphene diluent liquid prepared by a Hummers method to obtain neutral layered oxide graphene; S2: impregnating the neutral layered oxide graphene on a glass fiber fabric, drying to obtain a GF@GO composite material; S3: sequentially performing silver-ammonia solution coordination activation, formaldehyde reduction treatment and chemical copper plating treatment on the GF@GO composite material to obtain a GF@GO-Cu composite material; and S4: performing ultrasonic induction nickel-phosphorus nucleation and adsorption treatment on the GF@GO-Cu composite material through an ultrasonic activation solution, and then performing chemical nickel plating treatment to obtain a GF@GO-Cu / Ni composite material. The method has the characteristics of simple process, low cost, good mechanical strength and shielding performance.

The embodiment of the present application relates to the technical field of communication, and discloses a waveguide cavity antenna and a radar device.The waveguide cavity antenna comprises a metal base body provided with a radiation surface, a main transmission cavity, an auxiliary matching cavity, a radiation hole and a feed structure arranged on the metal base body;the first end of the auxiliary matching cavity is communicated with the main transmission cavity, the second end is communicated with the radiation hole, the radiation hole penetrates to the radiation surface, and the signal fed by the feed structure is transmitted to the auxiliary matching cavity through the main transmission cavity and radiated outward through the radiation hole.Through arranging the auxiliary matching cavity between the main transmission cavity and the radiation hole to match the impedance of the signal, the embodiment of the present application can reduce the impedance mismatch during electromagnetic wave propagation and radiation, reduce the reflection loss inside the cavity during high-frequency signal transmission, and improve the signal transmission efficiency of the antenna.

The invention discloses a circular polarization patch antenna based on geometric center feed and an antenna array, belongs to the technical field of antennas, and solves the problems of complex design, high cost, high system loss and low radiation efficiency of an existing circular polarization phased-array antenna. The feed point is arranged at the geometric center of the metal plate and the plurality of dielectric layers, and the high-frequency circular antenna and the low-frequency annular antenna are coaxial, so that the feed structure can feed at the geometric center of the antenna unit, the feed network distribution of the whole array antenna is not influenced when the antenna unit rotates, the design difficulty of the feed network is reduced, and the design efficiency is improved. The design of a feed network is simplified, the feed efficiency of the system is improved, two branches of the patch power divider extend the transmission path for transmitting radio frequency signals of the power branches due to the deviation angle, it is guaranteed that the phase difference of horizontal polarization and vertical polarization is 90 degrees under a certain deviation angle, the amplitude of vertical polarization and the amplitude of horizontal polarization are kept equal, and the power distribution efficiency of the system is improved. And circularly polarized radiation conditions are satisfied.