90results about How to "Improve electrical performance indicators" patented technology

The invention provides a method for achieving electronic building brick high-temperature packaging by filling Sn-based solder with micro-nano metallic particles. The method comprises the steps that the micro-nano metallic particles are prepared and mixed with a dispersing agent, a caking agent, diluent and scaling powder; a micro-nano metallic particle mixture is evenly mixed with pure Sn or Sn-based soldering paste; the Sn-based soldering paste is filled with the micro-nano metallic particles and placed on a base plate, alignment process of a part to be welded is completed, and pressure is exerted on the Sn-based soldering paste; the Sn-based soldering paste is put back in a reflow oven and experiences a preheating stage, an insulation stage, a reflowing stage and a cooling stage. According to the method for achieving electronic building brick high-temperature packaging by filling the Sn-based solder with the micro-nano metallic particles, the Sn-based solder is filled with the micro-nano metallic particles, connection and assembly of high-power devices or components can be achieved under the process condition of being compatible with traditional reflow soldering, when the devices serve at high temperature, metallic particles are formed inside a connector, excellent conductivity property and heat-conducting property are achieved, and the heat dissipation index and the electrical performance index of the electronic building brick can be significantly improved.

The invention discloses a process for preparing rare earth oxide doped ZnO-Bi2O3 family pressure-sensitive ceramic slurry, which comprises the following components (by molar portion): ZnO 91-98%, Bi2O3, Cr2O3, Co2O3, Ni2O3, MnCO3 and SiO2 each 0.1-1.0%, H3BO3 0.01-0.2%, Al(NO3)3 * 9H2O 0.001-0.01%, Sb2O3 0.5-2%, rare-earth oxide Ce2O3 or Gd2O3 0.1-1.0%.

The invention provides a satellite-based helical antenna. The antenna comprises a baffle board, an insulating board, a base, a helical antenna body and a protective cover. The baffle board, the base and the insulating board are fixed through screws. The insulating board is pressed between the baffle board and the base. The baffle board, the base and the insulating board are fixed as a whole. The lower end of a helical antenna body is fixed on the insulating board and the upper end thereof is fixed in the protective cover. When the helical antenna body is compressed to the greatest extent, the protective cover fully covers the base and the helical antenna body and is connected and fixed with the base through the screw. The helical antenna can be folded into a small size and has high compression ratio, the compressed antenna is convenient to store and install, has strong strength, and can bear large impact load; and the compressed antenna has no irreversible deformation, and can rapidly recover to the virgin state after being released.

The invention relates to a thickness design method of a radome. The method includes following steps: (1) performing discretization on the thickness of the radome according to the height direction of a radome body; (2) determining the value range of the thickness value, and giving an initial value to the thickness at a discrete point; (3) calculating a statistical value thereof according to the thickness value of the discrete point; (4) calculating a far field of an antenna, and extracting electrical performance indexes such as the gain G1 and the main beam position B1; (5) calculating a transmission coefficient of the random body, shown in the description, by employing a transmission line theory; (6) calculating a far field F' (theta, phi) of an antenna system with the radome, and drawing a far-field directional diagram; (7) establishing an optimization design model; and (8) determining whether the electric performance indexes and the thickness distribution of the random after optimization satisfy a preset requirement. According to the method, the electrical performance indexes of the radome are improved.

The invention discloses an insulated impregnating process for high-frequency transformers. The method can significantly improve the surface quality of high-frequency transformers and ensure that the surface of a transformer is completely covered; gaps between iron cores and windings are completely filled; and paint layers are glossy and free from paint protrusions, wrinkled skin and large-area flowing paint. The process is implemented through a technical scheme comprising the following: a) a step of impregnating with paint, which is to impregnate an iron core component with high-temperature epoxy glue, put the iron core component into a sealed container and bake for 2 hours; b) a step of winding, which is to wrap the iron core component in a glass cloth belt for insulation, wind primary and secondary windings and tie the glass cloth belt for insulation; c) a step of impregnating with paint, which is to bake the obtained product at 70+ / -10 DEG C for 0.5 hour; d) a step of baking, whichis to put the obtained product into a vacuum tank, vacuumize the vacuum tank, maintain pressure for 10 minutes, raise pressure to normal pressure, pressurize to between 0.3 and 0.4 MPa, maintain pressure for 20 minutes and bake for 2 hours; and e) a step of packaging, which is to pour high-temperature epoxy glue and put the obtained product into the same sealed container for baking. The high-frequency transformers manufactured by the process have the advantages of good thermal stability, excellent insulation performance and capability of completing the boost output of high-energy pulses.

This invention discloses a wide band dual polarized antenna array structure including: a surface radiation unit, a medium board, a feed bracket and a reflection board, in which, the surface radiation unit includes half-wave array arms and an end connection unit and the array arms are connected by the end connection unit, the feed bracket is placed between the medium board and the reflection board, the upper part contacts with the radiation unit via the medium board by its projection part, the lower part contacts with the reflection board by its projection part, the top of the inner conductor of the feed bracket is welded to the arrays of the surface radiation unit and the bottom passes through the gap of the reflection board but not contacts with it and welded with the feed network of the array, the hump part of the top of the outer conductor of the bracket is welded with the radiation unit, the bottom is welded with the reflection board so as to play the role of a choke.

The invention discloses an SMA radio frequency coaxial connector, relating to the technical field of coaxial connectors and aiming to promote the electric characteristics and the mechanical reliability and reduce contact resistance and radio frequency leakage. The connector comprises a left support, a right support, an outer conductor and an inner conductor, wherein the outer conductor is formed by jointing a left outer conductor with a right outer conductor, and the right end of the left outer conductor is jointed with the left end of the right outer conductor; the left support, the right support and the inner conductor are all fixed in an inner cavity of the outer conductor; the left support and the right support are respectively sleeved at the left end and the right end of the inner conductor, the left end and the right end of the left support are respectively arranged against the left end inner wall of the left outer conductor and the inner conductor, and the left end and the right end of the right support are respectively arranged against the inner conductor and the right end inner wall of the right support; a radial inward boss is arranged on the left end inner wall of the left outer conductor, and a radial inward boss is arranged on the right end inner wall of the right outer conductor. The connector has little radio frequency leakage in the process of matching use.

The present invention belongs to magnetoelectricity field, especially relates to an inductor element and manufacturing method thereof. The inductive element includes a magnetic rod, coil winded on magnetic rod and coating body outer the coil, coating body is coated outer the coil with an integrated injection molding modus which is characterized in that: magnetic conduction powdered ratio is 75-90% (weight proportion) in coating body. The production method of the inductive element is: the combination between the coil and the magnetic rod are imbedded into prearranged mold of injection molding machine; magnetic conduction powder and other addition agent discharges from hopper and is heated to 80-350 EDG C for forming fluid after mixed in proportion, and is coagulating molding after shot into mold for equably fully coating the surroundings of the coil and the magnetic rod; the required inductive element is obtained after demoulding. The present invention overcomes technology prejudice always existing in the present field, can obtain an inductive element without interstice on coating body, if the coating performance of the inductive element coating layer is more better, more compete shielding structure can be obtained.

The invention discloses a radio frequency coaxial micro-strip connecting device. The radio frequency coaxial micro-strip connecting device comprises a coaxial micro-strip connector. The coaxial micro-strip connector comprises outer conductors, a first inner conductor and insulating supports arranged between the outer conductor and the first inner conductor. A first insulating support and a first outer conductor, the first insulating support and the first inner conductor, a second insulating support and the first inner conductor as well as the second insulating support and the second outer conductor are respectively fixed and assembled to each other through matched limit steps in the axial direction of the coaxial micro-strip connector. According to the radio frequency coaxial micro-strip connecting device, the coaxial micro-strip connector is fixed by using the mechanical limit steps rather than by being filled with epoxy resin glue for fixing the inner conductor and the outer conductors, so that the problems of electromagnetic leakage hidden danger and the like of an existing coaxial micro-strip connector are effectively solved.

The invention provides a current balanced flat copper wire wave winding armature winding comprising a U-phase winding, a V-phase winding and a W-phase winding. The three parallel branches of the U-phase winding enter from the first layer of the same corresponding slot of each pair of poles and exit from the first layer of the same corresponding slot of each pair of poles. The three parallel branches of the V-phase winding enter from the first layer of the same corresponding slot of each pair of poles and exit from the first layer of the same corresponding slot of each pair of poles. The threeparallel branches of the W-phase winding enter from the first layer of the same corresponding slot of each pair of poles and exit from the first layer of the same corresponding slot of each pair of poles. According to the current balanced flat copper wire wave winding armature winding, the temperature non-uniformity of the outer, intermediate and inner windings during load operation of the motor is improved when the three branches are connected in parallel, and the electric performance index of the motor is improved. The biggest characteristic is that the current of the three parallel branchesis completely balanced and there is no current amplitude and phase difference among the three branches during load operation of the motor so as to improve the overall performance of the motor.

The invention provides a multi-frequency array antenna which can be simultaneously applied to a 4G network and a 5G network, so that the repeated utilization rate of the antenna is greatly increased.The FDD part of a 4G antenna and the TDD part of a 5G antenna are mutually combined and form an array by a multi-frequency array antenna so as to provide the functions of the 4G network and the 5G network; and the FDD part of the 4G antenna is placed on two sides of the TDD part of the 5G antenna to form a compact structure, and the height difference exists between a reflecting plates positioned right below the two rows of FDD antenna low-frequency arrays and a reflecting plate positioned right below the plurality of rows of TDD antenna arrays, so that the influence of radiation generated by the plurality of rows of TDD antenna arrays on the two rows of FDD antenna low-frequency arrays is reduced, and the isolation of a system can be improved. In addition, the high and low frequency arraysof the FDD part in the multi-frequency array antenna are combined in a coaxial nesting mode, so that the length of the antenna is greatly shortened, and the electrical performance index is good.

The invention discloses a vehicle-mounted knife-type antenna cover and a precise manufacturing method thereof. The antenna cover is formed by combining an inner surface layer, a functional layer, a bottom plane layer, a stop opening layer and an outer surface layer. The inner surface layer, the bottom plane layer, the stop opening layer and the outer surface layer are made of different specifications of high-intensity glass fiber prepregs. The functional layer is made of different materials of high-intensity glass fiber prepreg, a metal array and a nomex honey comb, thereby satisfying different functions of wide frequency, high wave transparency and invisibility. The inner surface layer, the stop opening layer, the functional layer, the bottom plane layer and the outer surface layer are successively laid on a core die sequentially, an outer die is assembled and a vacuum bag is used for sealing, and through a vacuum system and an oven, heating and solidification are achieved to form a whole body. A layering method and laying sequence are set, so high speed discharging and precise prefabrication of different layers can be achieved. By combining a metal outer die and a silicone rubber core die, the size precision of the antenna cover is ensured and the technique cost is reduced.

The invention relates to a dual-frequency rotary joint used for S single frequency and X single frequency transmission, including an X frequency band joint and an S frequency band joint. The X frequency band joint mainly includes a circular waveguide, a rectangular waveguide and a short-circuit cylinder. The two ends of the circular waveguide are connected to each other, the rectangular waveguide is arranged on the side circular surface of the two ends of the circular waveguide, and the rectangular waveguide and the circular waveguide are connected to each other through the coupling hole; the S-band joint mainly includes a coaxial waveguide, two work points device, magic T and waveguide elbow, the coaxial waveguide and the circular waveguide are coaxially arranged, and are located outside the circular waveguide, forming a transmission channel between the coaxial waveguide and the circular waveguide, and the two power dividers are respectively located on the coaxial Both ends of the waveguide are connected to the transmission channel between the coaxial waveguide and the circular waveguide, and the two horizontal signal ports of the magic T are connected to the two signal ports of the two-power splitter through the waveguide elbow. The invention is a rotary joint capable of simultaneously transmitting high-power radio frequency signals of S and X frequency bands, so as to solve the requirement of dynamic transmission of uplink high-power signals of S+X dual-frequency co-constructed antennas.

The invention relates to a tree-shaped antenna, which comprises two feeding poles and more than three pairs of oscillators, wherein each pair of oscillators are in one step; the more than three pairs of oscillators are increased step by step from top to bottom; the upper ends of two feeding poles are connected to form a herringbone; each pair of oscillators are respectively and symmetrically installed on the two feeding poles; each pair of oscillators have the same structure but different sizes; the oscillators are one-stage fractons or two-stage fractons; each fracton comprises three fraction arms which are successively connected and are in the horizontal pole shape; the junction of adjacent fracton arms is provided with a vertically-upward fracton arm or a vertically-downward fracton arm; the lengths of the fracton arms are equal; one end of three successively-connected fracton arms is connected with one feeding pole, and the other end is connected with a one-stage loading metal bar. According to the tree-shaped antenna disclosed by the invention, the volume of the antenna is greatly reduced, the problem that the common metre wave log-periodic antenna can not be suitable to install on an airborne platform is solved, antenna cross coupling is lowered, and the electrical property can satisfy the system use requirement.

The invention discloses a radio frequency coaxial connector, and relates to a radio frequency coaxial connector for connecting between a transmission cable and a printed circuit board. Aiming at the problem that the conventional similar radio frequency coaxial connector only has two contact points for electrical connection and too small elastic holding and seizing force. The radio frequency coaxial connector is characterized in that: annular protrusions are designed at the outer periphery of a rear neck of an inner conductor pin head; an inner conductor pin tail consists of two tail plates which are bent into arc shapes and matched up and down and of which the opening ends have duckbill shapes, and the cross sections of the two tail plates are matched crescents; a connecting sleeve is designed between the non-opening end of the inner conductor pin tail and the rear neck of the pin head; and an insulating inner sleeve is designed between the outer periphery of the inner conductor pin tail and an insulating sleeve, and is provided with annular protruding reinforcing ribs corresponding to the surface of the outer periphery of the middle part of the maximally spaced bent arc part of the two tail plates and corresponding to the end part of the connecting sleeve. Through trial, the radio frequency coaxial connector has the advantages of obviously reducing signal attenuation, having more reliability of elastic holding, reducing manufacturing cost, and reducing the consumption of copper alloy, gold and silver resources.

The invention discloses a high-temperature-resistant non-welded type radio-frequency coaxial cable connector which comprises an external conductor and a first inner conductor; the first inner conductor is sleeved with a high-temperature-resistant insulated support; a first limiting compensation step used for preventing the high-temperature-resistant insulated support from moving leftwards is arranged on the first inner conductor; the rear end of the first inner conductor is sleeved with a second inner conductor used for preventing the high-temperature-resistant insulated support from moving rightwards; the high-temperature-resistant insulated support is fixedly sleeved with a protective ring in a matched way; a second limiting compensation step used for preventing the protective ring from moving leftwards is arranged on the inner side wall of the outer conductor; and a check ring used or preventing the protective ring from moving rightwards is further fixedly arranged in the outer conductor. According to the radio-frequency coaxial cable connector, all parts are connected and fixed in a mechanical fixation mode, so that the reliability requirements of cable assemblies can be met.

A three-dimensional embattled miniaturization self-adaptation satellite navigation antenna comprises an antenna main array element, a main array element floor, a main array element array element feeder line, a main array element support, an antenna auxiliary array element, an auxiliary array element through connection floor, an auxiliary array element feeder line, an array floor, a main array element transmission network printed board, a main array element transmission network box, a main array element socket, an auxiliary array element transmission network printed board, an auxiliary array element transmission network box and an auxiliary array element socket. The three-dimensional embattled miniaturization self-adaptation satellite navigation antenna enables three-dimensional embattled design to be carried out on an antenna array element and reduces same frequency range coupling interference between the main array element and the auxiliary array element and between auxiliary array elements while meeting miniaturization requirements. Compared with a common plane multi-array element self-adaptation antenna, the three-dimensional embattled design promotes various electrical property indexes of the main array element, guarantees self-adaptation zero-setting performance of the auxiliary array element, and is applicable to miniaturization self-adaptation satellite navigation equipment.

The invention belongs to the field of data acquisition. A four-path data acquisition system based on a single-chip microcomputer comprises the components of the single-chip microcomputer, an A / D converter, an analog multipath changeover switch, a data amplifier, a pressure sensor, a temperature sensor, a DC power supply, a memory expansion, a 8279 chip driver, a keyboard and an LED display device. The single-chip microcomputer communicates with the A / D converter, the memory expansion and the 8279 chip driver. The A / D converter is connected with the DC power supply and the data amplifier through the analog multipath changeover switch. The data amplifier is connected with the pressure sensor and the temperature sensor. The 8279 chip driver is connected with the keyboard and the LED display device. A main program in the four-path data acquisition system mainly finishes operations of initializing a programmable chip 8279, setting an operation manner or initial state, and initializing a serial interface.

The invention discloses a UWB (ultra wide band) two-phase shifter. The two-phase shifter comprises an active balun, a first differential amplifier, a second differential amplifier, a third differential amplifier, a switch matrix, an RC orthogonal network and a single-pole double-throw switch, wherein the active balun receives a single-ended signal, and converts the single-ended signal into double-ended signals which are connected to two input ends of the first differential amplifier respectively; the first differential amplifier performs waveform shaping and gain compensation on the received two paths of signals, and selects different branches through a switch matrix to realize 180-degree phase shift; the double-end signal passes through the switch matrix and generates an orthogonal signalthrough a cascaded RC orthogonal network, and the rear stage of the RC orthogonal network is cascaded with the second differential amplifier and the third differential amplifier respectively; the single-pole double-throw switch selects different branches of the second differential amplifier and the third differential amplifier to generate 90-degree phase shift stepping quantity, so 90-degree phase shift quantity, 180-degree phase shift quantity and 270-degree phase shift quantity are realized. The phase shifter has the advantages of ultra-wide band, high phase shifting precision, good amplitude balance, simple control mode and high integration level.

The invention is suitable for the field of a filter and provides a radio-frequency filter and a duplexer. Two resonance modes are mixed in the radio-frequency filter, thereby greatly reducing the size of the filter, lowering the manufacturing cost of the filter and still acquiring higher electrical property and ultrahigh power capacity.

The invention discloses a packaging structure and a packaging method of a gallium nitride HEMT, a grid electrode of a gallium nitride HEMT chip to be packaged is located between a source electrode and a drain electrode, a second conductive bonding pad, a third conductive bonding pad and a base plate pin area are arranged and located on one side, close to the source electrode, of the chip, and a first conductive bonding pad is located on the other side, close to the drain electrode, of the chip; the first electric connection part is electrically connected with the drain electrode and the first conductive pad, the second electric connection part is electrically connected with the source electrode and the base plate pin area, the fourth electric connection part is electrically connected with the source electrode and the second conductive pad, and the third electric connection part is electrically connected with the grid electrode and the third conductive pad, so the voltage-withstanding distance between the electrodes of the chip can be met; the fourth electric connection part is electrically connected with the source electrode and the second conductive bonding pad to form a Kelvin source electrode so as to reduce the parasitic inductance of the driving loop; the gallium nitride HEMT chip to be packaged is fixed and electrically connected to the heat dissipation area, so the heat dissipation performance of the packaging structure is improved.

The invention discloses a high-precision radio frequency coaxial connector which relates to the technical field of coaxial connectors and solves the technical problems of improving electrical characteristics and mechanical reliability, reducing processing techniques and reducing processing cost. The connector comprises a support, an outer conductor and an inner conductor, wherein the outer conductor is formed by jointing a left outer conductor and a right outer conductor; the support is arranged in the outer conductor and is located at the joint part of the left outer conductor and the right outer conductor; the inner conductor is inserted in the outer conductor and penetrates through the support; and the support is columnar, both sides of the support are respectively provided with a left inner conductor compensation tank and a right inner conductor compensation tank around the periphery of the inner conductor, a left outer conductor compensation tank is located on the inner wall of the left outer conductor, and a right outer conductor compensation tank is located on the inner wall of the right outer conductor. The connector provided by the invention has excellent electrical characteristics, high mechanical reliability, simple processing technique, low processing cost and high product qualification rate.

The invention discloses a battery winding product and a disposable lithium metal battery. The battery winding product comprises an assembly formed by sequentially overlapping a positive electrode sheet on an inner layer, first diaphragm paper, a negative electrode sheet, and second diaphragm paper on an outer layer, wherein the assembly is wound into a cylindrical winding body; a negative electrode lug which is parallel to the center line of the winding body and extends towards the bottom of a steel casing is connected onto the negative electrode lug; a length of distance is formed between the tail end notch part of the positive electrode sheet and the negative electrode lug positioned on the inner side of the tail end notch part and on the negative electrode sheet. The battery winding product is characterized in that a metal conductor which extends in the direction consistent with the winding direction of the winding body is integrally arranged on the negative electrode lug; the free end of the metal conductor extends towards the tail end notch part of the positive electrode sheet and exceeds a length of distance; the free end of the metal conductor is electrically connected with the negative electrode sheet. The advantages that the condition that in the traditional technology, the negative electrode sheet covered by the insulating sheet cannot participate in a chemical reaction is avoided, all materials on the negative electrode sheet can participate in the reaction, and the electrical performance index of the battery is improved, are achieved.

The invention applies technique of activation and recovery to lead acid battery by using activator and activating instrument. Having high frequency impulse power supply, the activating instrument can send out high frequency impulse in frequency identical to natural frequency of molecule of compound sulfuric acid. The invention solves technical difficulties of low degree of recovery if the activator and activating instrument is applied solely in prior art. The invention is mainly applied to activation and recovery for each sort of lead acid battery (set).

The invention relates to a coaxial bunched cable for 3G (third generation) communication. The coaxial bunched cable comprises a physical foaming polyethylene insulating layer, an aluminum composite tape outer conductor, a tinned copper braid shielding layer and a photothermal-resistant polyethylene protective sheath which are arranged on the exterior of an inner wire of a copper-clad aluminium wire in sequence and also comprises a chemical foaming polyethylene padding core, a non-woven fabric inner protective layer, a cotton yarn tearing rope and a photothermal-resistant polyethylene outer protective sheath, wherein chemical foaming polyethylene padding cores are respectively arranged among four coaxial cables and are twisted together, the exterior of the cables are provided with the non-woven fabric inner protective layer and the photothermal-resistant polyethylene outer protective sheath, and the cotton yarn tearing rope is arranged between the non-woven fabric inner protective layer and the photothermal-resistant polyethylene outer protective sheath. The coaxial bunched cable provided by the invention has the characteristics of stable electric performance index, compact structure and simplicity and convenience in installation and construction, thus the electric performance index of the cable can be ensured not to change along with the change of installation places.

The invention discloses a universal reconfigurable phased-array antenna test truss. The truss comprises a support frame, a pitching adjusting mechanism and a truss structure. The truss structure comprises a plurality of trusses and a plurality of antenna fixing mechanisms. Horizontal sliding grooves which are vertically spaced and parallel are formed in the side face of the truss. Every two adjacent trusses are fixedly connected through a quick disassembly assembly, so that the horizontal sliding grooves of every two adjacent trusses are connected. Each antenna fixing mechanism is vertically arranged between the two corresponding horizontal sliding grooves, the end portions of the antenna fixing mechanisms are connected with the horizontal sliding grooves in a sliding mode, the lower endsof the trusses are hinged to the supporting frame, the two ends of the pitching adjusting mechanism are connected with the trusses and the supporting frame respectively, and the pitching adjusting mechanism can drive the truss structure to rotate relative to the supporting frame. The test truss can be suitable for testing various types of phased-array antennas.

The invention discloses a T-junction waveguide duplexer, which comprises an E-T power divider. The output end of the E-T power divider is connected with filters with different passbands; and the common end of the power divider is provided with a tuning bulge. Each filter is provided with metal diaphragms at intervals. The T-junction waveguide duplexer is simple in structure and easy to manufacture, solves the problem of large span of two working frequency bands of the duplexer, and improves the electrical performance index under the premise of keeping the basic performance index of the duplexer.

The invention discloses a mica-reinforced polypropylene composite material and a preparation method thereof. The mica-reinforced polypropylene composite material comprises the following components in percentage by weight: 50%-85% of polypropylene, 10%-40% of mica powder and 5%-10% of auxiliaries. The preparation method comprises the steps of: mixing propylene, mica powder and auxiliaries for three to ten minutes in a plastic tube, then pouring in a double-screw extruder, and extruding into a strip-shaped primary material under the conditions of the temperature of 200-260DEG C and rotating speed of 330-430 turns / minute; performing water tank and water cooling and then dicing into plastic particles. The mica-reinforced polypropylene composite material and the preparation method thereof have the beneficial effects that the rigidity and temperature resistance indexes of the material are improved but the electricity property and other physical performance indexes of the material cannot be reduced. The mica-reinforced polypropylene composite material is lighter in specific weight and the weight of plastic parts can be reduced. The mica-reinforced polypropylene composite material can replace a part of higher-cost plastic materials (such as reinforced nylon materials) so as to achieve the effect of lowering the cost. In addition, the mica-reinforced polypropylene composite material is easily machined into various plastic parts. The preparation method is simple, the process is easy to control and in the yield is high.

The invention provides a broadband and low-fluctuation band-pass LC filter. According to the filter, ordinary inductors are replaced by winding magnetic rings with small temperature drift, good stability, and high Q value, and 0805 packaging capacitors are employed so that the stability of electrical parameters is guaranteed, and the electrical performance index of the filter is greatly increased. Penetrating holes are arranged at four corners around a PCB so that input, output, and grounding signals can all be perfectly transmitted to the PCB and components. Besides, a transfer function expansion equation of the filter is designed based on the design principle of in-band fluctuation, standing waves, and optimal dimension, and the capacitors and the winding magnetic rings are arranged strictly according to the equation so that the filter is advantaged by small packaging, large bandwidth, low insertion loss, high rectangular degree, high stop-band suppression, low standing wave, and low in-band fluctuation.

The invention relates to a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation of naphthenic base distillate oil, which comprises the following steps: 1) the naphthenic base distillate oil enters a first hydrogenation reactor and passes through a hydrofining reaction zone and a deep dearomatization reaction zone to realize hydrogenation removal of sulfur and nitrogen compounds and hydrogenation saturation of aromatic hydrocarbon in the oil product; 2) enabling the reactant flow to enter a second reactor, and respectively passing through a selective ring-opening reaction zone, an isomerization pour point depression reaction zone and a finishing reaction zone to realize selective ring opening of a polycyclic compound, isomerization of paraffin (branched chain) and saturation of cracked olefin; and 3) carrying out gas-liquid separation and rectification separation on the reaction product to obtain a low-aromatic transformer oil fraction and a clean light oil fraction. The method is suitable for upgrading and value-added processing of the transformer oil base oil from naphthenic crude oil and coal-based oil product fractions, has the characteristics of simple process flow, small device investment scale and high operation safety, and has the technical advantages of high transformer oil base oil yield, good product quality, environmental friendliness and the like.