CN114063016A - Method for improving electromagnetic compatibility of rotary phased array radar - Google Patents
Method for improving electromagnetic compatibility of rotary phased array radar Download PDFInfo
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- G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
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- G—PHYSICS
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- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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Abstract
The invention discloses a method for improving electromagnetic compatibility of a rotary phased array radar, aiming at the problem that RE102 indexes of the rotary phased array radar exceed standards, the electromagnetic immunity of equipment is improved by a grounding design, electromagnetic mutual interference of adjacent space areas is isolated by a metal material or a coating, an electromagnetic energy transmission path is cut off by an interference filter, and the radar is grounded, shielded and filtered.
Description
Technical Field
The invention belongs to the technical field of radars, and particularly relates to an electromagnetic compatibility technology.
Background
With the continuous development of scientific technology, information-based systems are more and more complex, electronic devices tend to be more and more integrated, miniaturized and networked, more and more electronic devices are loaded on the same platform, and the requirements on electromagnetic compatibility are higher and higher. The electromagnetic environment is increasingly complex and severe, and electronic and electrical equipment and systems face more and more electromagnetic interference, so that the probability of performance reduction and function loss is obviously increased. Electronic and electrical devices and systems utilize the electromagnetic spectrum, and in a common electromagnetic environment, it is important to avoid unacceptable degradation due to electromagnetic radiation and sensitivity and to improve their functionality.
The radar is a complex and huge system integrated by a plurality of specifications and a large number of electronic devices, generally coordinates with systems such as communication, finger control and navigation, and has obvious and serious incompatible problems such as electromagnetic self-interference and mutual interference.
The GJB151B-2013 electromagnetic emission and sensitivity requirements and measurement, the RE102 project limit value requirement is the most strict, and the technical difficulty is great from the view of the electromagnetic field and signal analysis basic principle. The radar is a complex and numerous electronic device, high, medium and low frequency devices are complete, cables are densely distributed, and particularly, an internal secondary power supply, a servo transmission mechanism, a transceiving branch circuit and the like are potential radiation sources. Due to the fact that limitation of telecommunication, structure, process and the like of influencing factors is large, under the condition of limited space, weight and size, high radar technology tactical index requirements are achieved, especially a transmitting and receiving front is an open radiation source, and the requirements of GJB151B are difficult to completely meet in a low frequency band.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for improving the electromagnetic compatibility of a rotary phased array radar.
Improve the electromagnetic immunity of equipment with the ground connection design, with the electromagnetic mutual interference of metal material or coating isolation adjacent space region, cut off electromagnetic energy propagation path with interference filter, include: the ground wire in the high-frequency box is directly grounded by adopting a box shell to inhibit radiation caused by field-wire coupling, power cables and signal cables in the high-frequency box, the turntable and the comprehensive processing box are separately arranged, power equipment and receiving wave control equipment in the high-frequency box are separately arranged from left to right, and a servo and a left cavity and a right cavity of the signal processing equipment in the comprehensive processing box are separately arranged to reduce mutual interference; the chassis, the high-frequency box and the printed board adopt radiation shielding design, shielding measures are taken by a T/R component, an R component, a crystal oscillator, a digital receiver and a digital array component in the high-frequency box, the comprehensive processing box, an internal cavity of the antenna pedestal and a pitching driver, electromagnetic shielding design is adopted, conductive processing or a conductive gasket is adopted by matching with a contact surface and an electric connector mounting surface, and the exposed cable is additionally provided with shielding protection; a power filter and a piercing filter capacitor are installed at a power inlet of a high-frequency box and a power outlet of a fan, a power supply and a signal filter are installed at an adapter plate of an antenna feed servo assembly, a power supply of the high-frequency box, a pitching drive, an azimuth drive and a servo signal port, and a power supply and a signal filter are installed at a signal processing power supply, a servo power supply and a servo signal port in the comprehensive processing box; the servo power supply, the azimuth drive, servo signal of the servo control unit in the comprehensive processing box install shielding filtering integration subassembly additional, restrain conducted interference and cable radiation interference, the power and control signal of every single move driver install power signal combined filter additional, the conducted interference through restraining the cable realizes the suppression to the radiation, 360 overlap joints are realized with quick-witted case connector socket to the feeder shielding layer of high frequency case, reduce the cable radiation, revolving stage bottom azimuth motor servo drive and servo control input install the filter additional.
The ground wires of electronic products are classified into two types: one is for the circuit to work properly, called signal ground; another type is to ensure the electrical safety of the equipment, called safety ground. In general, the electromagnetic interference problems caused by the ground wire include: the ground wire current and the ground wire impedance cause different potentials of each point of the ground wire, so that the circuit works abnormally; improper ground wire design leads to large signal current loop area, strong electromagnetic radiation is generated, and radiation interference is caused; the larger signal loop area increases mutual inductance coupling between circuits, resulting in abnormal circuit operation. The multistage circuit avoids circular grounding to the unit circuit, and current flows from the small signal unit to the large signal unit according to the distance between the circuits and the use frequency.
Furthermore, the signal frequency is lower than 1MHz or the length of the ground wire is not more than 1/20 wave length, single point grounding is adopted to connect the ground wires of all circuits to the same point of the common ground wire, thereby avoiding the loop interference of the ground wire; the signal frequency is higher than 10MHz or the length of the ground wire exceeds 1/20 wave length, all circuits are connected to the public ground wire nearby by multipoint grounding, and the length of the ground wire is shortened; the characteristics that the capacitor and the inductor have different impedances at different frequencies are utilized, and mixed grounding is adopted, so that the system has different grounding structures for signals with different frequencies.
Specifically, the signal circuit, the power circuit and the high-low frequency circuit use independent low-impedance loops, do not use a common loop, and do not use a chassis as a grounding loop; the grounding wire is a metal conductor with low resistance inductance, and the sectional area of the grounding wire is not less than 25mm2The grounding direct current resistance is less than 10m omega; the digital grounding and the analog grounding are respectively connected in a classified way, and the analog circuit adopts shielding measures to converge the last point for grounding; the single-point grounding unit socket shell does not contact the unit shell, and the single-point grounding principle is not damaged among the units; the multipoint grounding unit adopts a near grounding mode, and the printed circuit is grounded in a large area and then connected to a signal grounding socket core wire; the metal shell is arranged near the high-frequency radiation end and is contacted with a person, and a grounding measure is taken; the cable that DC power supply and control signal used installs area insulating sheath additional, and key signal cable adopts double-deck shielded cable, and shielding layer both ends and connector housing zonulae occludens.
The shielding body plays a role in offsetting energy, reflecting energy and absorbing energy to external interference electromagnetic waves or internal electromagnetic waves from a lead, a cable, a component, a circuit or a system and the like, and the receiving circuit, equipment or the system is wrapped by the shielding body, so that external electromagnetic radiation can be prevented from entering the equipment or the system, and the radiation electromagnetic interference inside the equipment or the system is limited in a certain area. The typical electromagnetic leakage factors of electronic device cases are mainly classified into three types: the assembling gaps of the chassis are the factors which generally affect the shielding effectiveness of the chassis to the maximum, and comprise the gap between a chassis cover plate and a chassis body, the connecting gap of a chassis assembling surface and the gap between the chassis body and a connector; the chassis radiating structure adopts air cooling or liquid cooling for radiating; the electric penetrates into the structure, and external interference electromagnetic waves are introduced into the case through the case connecting wire.
Furthermore, the conductive gasket is adopted to fill the assembly gap, so that the contact transfer impedance between the upper metal piece and the lower metal piece of the gap is reduced, the screw distance between the case and the cover plate is adjusted, and the electromagnetic leakage is reduced; the case with large size is radiated by a ventilation waveguide structure, and the case with small space is radiated by a liquid cooling structure; and installing a filter in the electrical penetration, and selecting an aviation connector with a filtering function.
Specifically, the sealing groove formed in the case has a rectangular cross section and contains 90% -95% of the volume of the conductive rubber strip, and the conductive rubber is made of a material with a constant volume; the groove width is larger than the diameter of the conductive rubber, the groove depth is smaller than the height of the conductive rubber, and the radius of the corner radian is larger than 3 times of the groove width.
Lapping is the process of establishing a low impedance path between two metals to provide a uniform structure for current flow to avoid interference. The good overlapping can thoroughly play the functions of shielding and filtering, reduce the radio frequency potential difference and current loop in the grounding system, prevent static electricity, reduce the danger of lightning stroke and electromagnetic pulse and prevent people from being shocked by electricity by mistake. An untreated overlap increases the degree of interference and is even more hazardous to personnel.
Furthermore, the lapped joint or contact surface is kept clean without an insulating protective coating; adopting fusion welding, overlaying welding or brazing to form permanent connection; the connecting cables are few and short, and the lap joint direct current resistance of the connector is not more than 10m omega; the lap joint sheet or the jumper wire is short, wide and thin, the ratio of the wavelengths is small, and the length ratio is less than 5; the unit chassis and the base of the cabinet are in good electrical contact with the mounting rack, and the detachable panel and the cover plate are connected by adopting conductive elastic pads or metal spring pieces; the shielding of the permanent joint adopts a connection welding method, and the distance between welding spots of spot welding is not more than 5 cm; the shielding matching surface of the non-permanent joint is fastened by screws, and the screw distance is reduced.
There are two ways electromagnetic interference may be transmitted from or into the device: the electromagnetic wave radiation propagates from the space, is solved by electromagnetic shielding, propagates along a conductor in the form of current conduction, needs to be additionally provided with an interference filter, organically combines the two technologies, and cuts off all paths of electromagnetic energy propagation. The switch power supply works in a high-power pulse state to form high-frequency conduction disturbance, the pulse circuit generates strong electromagnetic radiation during working to induce the circuit to form common-mode conduction disturbance, and a power line filter is installed at the inlet of a power line. The interference filter is a passive low-pass network composed of inductors, capacitors and common-mode inductance elements and is divided into a power line filter and a signal line filter. The signal line filter has large insertion loss to electromagnetic interference and can not distort normal working signals of products. The leakage current of the power line filter cannot exceed the standard, and when the load current is large, the inductor in the circuit cannot be saturated. The outer dragging cable of the cabinet plays a role of an antenna, receives space electromagnetic waves and transmits the space electromagnetic waves to equipment, so that interference is formed on a circuit, and a proper filter is installed at the interface of the cable and the circuit.
Furthermore, a power filter is additionally arranged at the power input end of each extension, and a signal filter is additionally arranged on the key signal line and the servo driving signal line; the method comprises the following steps that a large-capacity electrolytic capacitor and a small-capacity high-frequency decoupling capacitor are additionally arranged at the power supply input end of a printed board; the insertion loss and the impedance of the filter are changed along with the frequency and are matched with the impedance.
Specifically, after the power filter is additionally provided with a shield, the power filter is arranged at a power inlet of equipment or a shielding shell, and a shield body is lapped with an equipment shell; a shielding layer is additionally arranged between an input line and an output line of the filter. The input line and the output line of the filter do not cross; if the filter is mounted close to the bottom plate, the input line needs to be additionally provided with a shield and is not bound with other lines; and an external interface socket of the cabinet case is additionally provided with a signal filter.
Aiming at the problem that the RE102 index of the rotary phased array radar exceeds the standard, the method for improving the grounding, shielding and filtering of the radar is scientific, simple in means, remarkable in effect of improving the electromagnetic compatibility of the radar, and capable of meeting the relevant requirements of GJB151B, and the performance of the RE102 of the radar meets the requirements of the national military standard in multiple tests.
Drawings
Fig. 1 is a single point ground schematic, fig. 2 is a multiple point ground schematic, fig. 3 is a hybrid ground schematic, fig. 4 is a cabinet design schematic, fig. 5 is a seal slot corner schematic, and fig. 6 is a conductive gasket installation schematic.
Detailed Description
The technical scheme of the invention is specifically explained in the following by combining the attached drawings.
The grounding is an important measure for improving the electromagnetic compatibility of electronic and electrical equipment, and the correct grounding can not only effectively improve the electromagnetic immunity of the equipment, but also inhibit the electronic and electrical equipment from emitting electromagnetic waves to the outside. The ground wires of electronic products are largely classified into two types according to their functions: one is for the circuit to work properly, called signal ground; another type is to ensure the electrical safety of the equipment, called safety ground. Generally, the problem of electromagnetic interference caused by the ground wire is substantially as follows:
(1) the ground wire current and the ground wire impedance cause different potentials of each point of the ground wire, which contradicts with the assumption that the ground wire potential is certain, and causes abnormal circuit operation;
(2) the problem of radiation interference is caused by strong electromagnetic radiation generated by a current loop with a large area due to the fact that the ground wire is improperly designed;
(3) the larger signal loop area increases mutual inductance coupling between circuits, resulting in abnormal circuit operation.
Therefore, in order to avoid the interference generated by the ground wire, the ground wire must be designed at the initial stage of the system design, and the ground wire is mainly classified into the following three types:
single-point grounding: the ground of all circuits is connected to the same point of the common ground. The advantage is that the problem of ground wire loop interference is avoided, and the disadvantage is that the ground wire is long and the impedance is large, which can cause resonance, as shown in fig. 1.
(2) Multipoint grounding: all circuits are connected nearby to a common ground. The advantage is that the length of the ground wire is shortened, the disadvantage is that the structure of multipoint earthing forms many ground wire loops, and further the electromagnetic field of the space and the potential difference on the ground wire can interfere the circuit, as shown in fig. 2.
(3) Mixed grounding: the characteristics that devices such as capacitors and inductors have different impedances under different frequencies are utilized to form a hybrid grounding system. The advantage is that the system has different grounding structures for signals with different frequencies, and the disadvantage is that the design workload is large and the circuit is complex, as shown in fig. 3.
The grounding of the unit circuit in the multi-stage circuit must make the current in the unit circuit flow from the small signal unit to the large signal unit, and the multi-stage circuit should avoid circulating grounding. The ground circuit should be determined according to the distance between circuits and the frequency used. Generally, single-point grounding is adopted when the frequency is below 1MHz, multipoint grounding is carried out when the frequency is higher than 10MHz, the frequency is between 1MHz and 10MHz, the single-point grounding is used when the length of a ground wire is not more than 1/20 lambda, and the multipoint grounding is used when the length of the ground wire is more than 1/20 lambda while the frequency is between 1MHz and 10 MHz.
In addition to the above requirements, the following points are also required in engineering design:
(1) a common loop is not required to be used in the signal circuit, the power circuit and the high-low frequency circuit, and an independent low-impedance loop is required to be used respectively, so that a chassis is not used as a grounding loop.
(2) All ground wires should be as short, straight and wide as possible. The grounding wire is made of a metal conductor or a lead with low resistance inductance, and the grounding sectional area is not less than 25mm2And the ground wire grounding direct current resistance is less than 10m omega.
(3) For more demanding devices and components, the signal ground should be further classified according to circuit performance, and can be generally classified into digital ground, analog ground, and the like, various ground classification links, and the last point is grounded.
(4) For a unit requiring one point grounding, when the socket is used, the socket shell is not contacted with the unit shell, and signals requiring one point grounding between the units are required to be coordinated when being connected, so that the principle of one point grounding is not damaged after the connection.
(5) For units requiring multiple grounds, the signal ground is grounded nearby, and the printed circuit is grounded over a large area and then connected to the signal ground receptacle core.
(6) A metal case installed near the high-frequency radiation end to be easily touched by a person should be provided with a grounding measure.
(7) A shielded cable that is used for DC power supply and control signal cable to select to take insulating sheath, key signal cable adopts double-deck shielding, shielding layer both ends and connector housing zonulae occludens.
(8) In the analog/digital mixed circuit in the branch machine, the analog circuit should adopt shielding measures, the shielding should be connected to the signal ground of the analog circuit nearby, and the signal ground of the digital/analog circuit in the cabinet can be connected only at one point.
Shielding is adopted to electromagnetically isolate two space regions through a metal material (or a metal coating on an insulating material), and the purposes are two:
(1) preventing extraneous electromagnetic radiation from entering the device (or system);
(2) the radiated electromagnetic interference inside the device (or system) is confined to a certain area.
Because the shielding body plays a role in canceling energy, reflecting energy and absorbing energy to external interference electromagnetic waves or internal electromagnetic waves from wires, cables, components, circuits or systems and the like, the receiving circuits, equipment or systems can be prevented from being influenced by external electromagnetic interference by wrapping the receiving circuits, equipment or systems by the shielding body. The specific method comprises the following steps:
(a) shielding of cabinet
The shielding effectiveness of the cabinet of the electronic equipment at 100 KHz-1 GHz is more than or equal to 60 dB. The specific requirements are as follows.
Generally, the electronic equipment cabinet is designed as shown in fig. 4, and typical electromagnetic leakage elements of the electronic equipment cabinet mainly include three types:
(1) assembling gaps of the case: a gap between the cover plate of the case and the case, a connecting gap between the assembly surface of the case, a gap between the case and the connector, etc.;
(2) case heat dissipation structures;
(3) an electrical feedthrough structure;
assembly gaps of the chassis: is generally the factor that most affects the shielding effectiveness of the chassis. In engineering, a conductive gasket is mainly adopted to fill a gap, so that contact transfer impedance between an upper metal piece and a lower metal piece of the gap is reduced; and the electromagnetic leakage is reduced by selecting proper screw spacing between the chassis and the cover plate and the like.
Case heat dissipation structure type: the heat dissipation can adopt air cooling or liquid cooling. For a case with large size, the size of the area and the size of the linearity are large, and heat dissipation can be performed by adopting a special ventilation waveguide structure in engineering; the shielding case with high heat dissipation requirement and small structural space can adopt a liquid cooling structure.
An electrical penetration structure: in order to prevent external interference electromagnetic waves from being introduced into the case through the case connecting wire, a filter can be installed, and an aviation connector with a filtering function can be selected.
Assembly gap design of cabinet
In order to prevent the conductive rubber strip from being crushed, the conductive rubber must be matched with the sealing groove when in actual use, so that the sealing performance of the conductive rubber is greatly influenced by the sectional shape of the sealing groove.
(1) The sealing groove of the chassis has a rectangular cross section, and the groove width of the sealing groove has to be larger than the diameter of the conductive rubber and the groove depth has to be smaller than the height of the conductive rubber in consideration of the deformation of the conductive rubber.
(2) The conductive rubber belongs to a material with a constant volume, and the designed sealing groove can contain 90% -95% of the volume of the conductive rubber strip.
(3) The sealing groove at the corner of the chassis should be processed as shown in fig. 5, and the radius R of the corner arc is more than three times of the groove width w.
The lap joint creates a low resistance path between the two metals, which aims to provide a uniform structure for the current to avoid interference. The well-processed lapping can completely play the functions of shielding and filtering, reduce the radio frequency potential difference and current loop in a grounding system, prevent static electricity, reduce the danger of lightning stroke and electromagnetic pulse and prevent people from being shocked by electricity by mistake. However, an untreated overlap increases the degree of interference and is even more hazardous to personnel. Therefore, proper overlap should be noted for the following points:
(1) reliable bridging, clean contact points or surfaces, no protective insulating coating, and corrosion protection are required.
(2) Preferably a permanent connection or a permanent connection formed by welding, overlaying or brazing.
(3) The connecting cable is less demanding and shorter, all the contact surfaces to be connected to ground must not be coated with an insulating coating, and the lap direct current resistance of the connector should not exceed 10m omega.
(4) It is required that the strap or jumper be short, wide, thin, the ratio of strap (or jumper) to wavelength be as small as possible, and the ratio of the length of the strap (or jumper) should be less than 5.
(5) Each unit case, base and mounting bracket of the cabinet should form good electrical contact. The detachable panel and the cover plate can be contacted and connected by a conductive elastic pad or a metal spring piece if necessary.
(6) The rotating, moving parts are required to have good electrical contact.
The shielding of the joint is of vital importance and is mainly divided into the following two types:
(1) permanent joint shielding by means of joint welding, if spot welding, the distance between welding points is not more than 5 cm.
(2) Shielding of the non-permanent joint, wherein the matching surfaces of the detachable joint are generally fastened by screws, and the screw distance is reduced; removing the non-conductive substances on the surface; the joint surface is provided with a conductive pad which can be made of conductive cloth, conductive rubber plates, conductive rubber strips and other materials. The mounting of the conductive pads is shown in fig. 6.
There are only two ways electromagnetic interference can be transmitted from or into the device:
(1) propagating from space in the form of electromagnetic wave radiation;
(2) propagating along the conductor in the form of current conduction.
Electromagnetic shielding addresses spatial propagation, while conductor propagation requires passage through interference filters. Only by organically combining the two technologies together can all the ways of electromagnetic energy propagation be cut off.
With the widespread use of switching power supplies, it has become a necessary measure to install a power line filter at the power line inlet. Because the switching power supply works in a high-power pulse state, the pulse current can form high-frequency conduction disturbance, in addition, the pulse circuit generates strong electromagnetic radiation during working, and the radiation induces the circuit to form common-mode conduction disturbance.
The interference filter is a passive low-pass network composed of an inductor, a capacitor and a common-mode inductor element. In design, the interference filter can be divided into two types, namely a power line filter and a signal line filter, and the two types of filters are identical in terms of circuit and are both low-pass filters, but each has some special points.
(1) Besides large insertion loss to electromagnetic interference, the signal line filter also ensures that the normal working signal of the product cannot be seriously influenced and cannot cause signal distortion.
(2) The power line filter is also considered to meet the safety requirement that the leakage current must not exceed the standard. In addition, it is also noted that when the load current is large, the inductance in the circuit cannot saturate (saturation will cause the filter performance to degrade).
Meanwhile, for some equipment, although the cabinet is well shielded, the electromagnetic compatibility test requirements cannot be met, and the reason is that the external trailing cable of the cabinet plays a role of an antenna to effectively receive spatial electromagnetic waves and transmit the spatial electromagnetic waves to the equipment so as to interfere with a circuit, so that one of the methods for solving the problem is to install a proper filter at the interface of the cable and the circuit.
When the filter is used, the characteristics of insertion loss and impedance change along with frequency must be met, and the impedance matching requirement should be met.
During the filter design and selection, the following points should be noted:
(1) a power filter is added to the power input end of each extension, and a signal filter is added to a key signal line such as a servo signal line for servo driving.
(2) A large-capacity electrolytic capacitor and a small-capacity high-frequency decoupling capacitor are added to the power input terminal on the printed board.
(3) When the filter is used, the characteristics of insertion loss and impedance change along with frequency must be met, and the impedance matching requirement should be met.
Filter leads and mounting locations are also very problematic, taking into account:
(1) the power filter is installed at the power inlet of the equipment or the shielding case and is shielded, and the shielding body is well lapped with the equipment shell.
(2) The filter should have a shielding layer between the input line and the output line. The input and output lines of the filter cannot cross.
(3) If the cabinet is in a limited position, the filter is mounted against the bottom plate, and the input wires are well shielded wires and cannot be bound together with other wires.
(4) The cabinet case is provided with an external interface socket and a signal filter if necessary.
The above-described embodiments are not intended to limit the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the present invention.
Claims (8)
1. A method for improving electromagnetic compatibility of a rotating phased array radar is characterized by comprising the following steps: improve the electromagnetic immunity of equipment with the ground connection design, with the electromagnetic mutual interference of metal material or coating isolation adjacent space region, cut off electromagnetic energy propagation path with interference filter, include: the ground wire in the high-frequency box is directly grounded by adopting a box shell to inhibit radiation caused by field-wire coupling, power cables and signal cables in the high-frequency box, the turntable and the comprehensive processing box are separately arranged, power equipment and receiving wave control equipment in the high-frequency box are separately arranged from left to right, and a servo and a left cavity and a right cavity of the signal processing equipment in the comprehensive processing box are separately arranged to reduce mutual interference; the chassis, the high-frequency box and the printed board adopt radiation shielding design, shielding measures are taken by a T/R component, an R component, a crystal oscillator, a digital receiver and a digital array component in the high-frequency box, the comprehensive processing box, an internal cavity of the antenna pedestal and a pitching driver, electromagnetic shielding design is adopted, conductive processing or a conductive gasket is adopted by matching with a contact surface and an electric connector mounting surface, and the exposed cable is additionally provided with shielding protection; a power filter and a piercing filter capacitor are installed at a power inlet of a high-frequency box and a power outlet of a fan, a power supply and a signal filter are installed at an adapter plate of an antenna feed servo assembly, a power supply of the high-frequency box, a pitching drive, an azimuth drive and a servo signal port, and a power supply and a signal filter are installed at a signal processing power supply, a servo power supply and a servo signal port in the comprehensive processing box; the servo power supply, the azimuth drive, servo signal of the servo control unit in the comprehensive processing box install shielding filtering integration subassembly additional, restrain conducted interference and cable radiation interference, the power and control signal of every single move driver install power signal combined filter additional, the conducted interference through restraining the cable realizes the suppression to the radiation, 360 overlap joints are realized with quick-witted case connector socket to the feeder shielding layer of high frequency case, reduce the cable radiation, revolving stage bottom azimuth motor servo drive and servo control input install the filter additional.
2. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 1, wherein said improving electromagnetic immunity of the device with a grounded design comprises: the signal frequency is lower than 1MHz or the length of the ground wire is not more than 1/20 wave length, the single point grounding is adopted to connect the ground wires of all circuits to the same point of the public ground wire, so as to avoid the loop interference of the ground wire; the signal frequency is higher than 10MHz or the length of the ground wire exceeds 1/20 wave length, all circuits are connected to the public ground wire nearby by multipoint grounding, and the length of the ground wire is shortened; the characteristics that the capacitor and the inductor have different impedances at different frequencies are utilized, and mixed grounding is adopted, so that the system has different grounding structures for signals with different frequencies.
3. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 2, further comprising: the signal circuit, the power circuit and the high-low frequency circuit use independent low-impedance loops, do not use a common loop, and do not use a chassis as a grounding loop; the grounding wire is a metal conductor with low resistance inductance, and the sectional area of the grounding wire is not less than 25mm2The grounding direct current resistance is less than 10m omega; digital ground and analog ground eachThe analog circuit adopts shielding measures and converges the last point to be grounded; the single-point grounding unit socket shell does not contact the unit shell, and the single-point grounding principle is not damaged among the units; the multipoint grounding unit adopts a near grounding mode, and the printed circuit is grounded in a large area and then connected to a signal grounding socket core wire; the metal shell is arranged near the high-frequency radiation end and is contacted with a person, and a grounding measure is taken; the cable that DC power supply and control signal used installs area insulating sheath additional, and key signal cable adopts double-deck shielded cable, and shielding layer both ends and connector housing zonulae occludens.
4. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 1, wherein said isolating electromagnetic interference of adjacent spatial regions with a metallic material or coating comprises: the conductive gasket is adopted to fill the assembly gap, so that the contact transfer impedance between the upper metal piece and the lower metal piece of the gap is reduced, the screw distance between the case and the cover plate is adjusted, and the electromagnetic leakage is reduced; the case with large size is radiated by a ventilation waveguide structure, and the case with small space is radiated by a liquid cooling structure; and installing a filter in the electrical penetration, and selecting an aviation connector with a filtering function.
5. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 4, further comprising: the sealing groove formed in the case is of a rectangular cross section and is used for accommodating 90% -95% of the volume of the conductive rubber strip, and the conductive rubber is made of a material with unchanged volume; the groove width is larger than the diameter of the conductive rubber, the groove depth is smaller than the height of the conductive rubber, and the radius of the corner radian is larger than 3 times of the groove width.
6. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 1, wherein said isolating electromagnetic interference of adjacent spatial regions with a metallic material or coating comprises: the lapped joint or contact surface keeps clean without an insulating protective coating; adopting fusion welding, overlaying welding or brazing to form permanent connection; the connecting cables are few and short, and the lap joint direct current resistance of the connector is not more than 10m omega; the lap joint sheet or the jumper wire is short, wide and thin, the ratio of the wavelengths is small, and the length ratio is less than 5; the unit chassis and the base of the cabinet are in good electrical contact with the mounting rack, and the detachable panel and the cover plate are connected by adopting conductive elastic pads or metal spring pieces; the shielding of the permanent joint adopts a connection welding method, and the distance between welding spots of spot welding is not more than 5 cm; the shielding matching surface of the non-permanent joint is fastened by screws, and the screw distance is reduced.
7. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 1, wherein said cutting off the electromagnetic energy propagation path with an interference filter comprises: a power filter is additionally arranged at the power input end of each extension, and a signal filter is additionally arranged on the key signal line and the servo driving signal line; the method comprises the following steps that a large-capacity electrolytic capacitor and a small-capacity high-frequency decoupling capacitor are additionally arranged at the power supply input end of a printed board; the insertion loss and the impedance of the filter are changed along with the frequency and are matched with the impedance.
8. The method for improving electromagnetic compatibility of a rotating phased array radar as claimed in claim 7, further comprising: after the power filter is additionally provided with the shielding, the power filter is arranged at a power inlet of the equipment or the shielding shell, and the shielding body is lapped with the equipment shell; a shielding layer is additionally arranged between an input line and an output line of the filter. The input line and the output line of the filter do not cross; if the filter is mounted close to the bottom plate, the input line needs to be additionally provided with a shield and is not bound with other lines; and an external interface socket of the cabinet case is additionally provided with a signal filter.
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| CN202111356126.9A CN114063016A (en) | 2021-11-16 | 2021-11-16 | Method for improving electromagnetic compatibility of rotary phased array radar |
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| CN202111356126.9A CN114063016A (en) | 2021-11-16 | 2021-11-16 | Method for improving electromagnetic compatibility of rotary phased array radar |
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| CN115643740A (en) * | 2022-10-27 | 2023-01-24 | 中国航空工业集团公司雷华电子技术研究所 | RS422 communication and direct current 28V power supply electric field radiation emission rectification verification device and method |
| CN115768093A (en) * | 2022-11-23 | 2023-03-07 | 彭毅 | Electromagnetic shielding device and distribution box |
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Application publication date: 20220218 |