MANUAL FOR MODELS: SCB SCB SCB107E METERS CASSEGRAIN EARTH STATION ANTENNAS

Transcription

1 MANUAL FOR MODELS: SCB SCB SCB107E METERS CASSEGRAIN EARTH STATION ANTENNAS I

2 C o n t e n t 1 General Technical Specifications Specifications of the model SCB Specifications of the model SCB Specifications of the model SCB107E Structural Character and Operational Principle System Structural Character Antenna Structural Character Antenna Pedestal Structure Feed Structure Antenna Operation Principle Maintenance Operation and Maintenance of Antenna Operation and Maintenance of Servo Equipment I

3 1 General The 11m antenna, a synthetic Cassegrain dual-reflector antenna models SCB37-110, SCB and SCB107E-110, adopts some new technologies, such as high-performance corrugated horn and broadband microwave network, etc. The antenna performance meets the requirements of ITU-R/ITU-T INTELSAT IESS-207 and Resolution 572 of Anatel standards. It is not only provided with many excellent electric performances, such as high efficiency, low sidelobe, low cross polarization, low Voltage standing waves ratio (VSWR), high G/T value, but also with excellent characters including appropriate structural design, strong wind resistance ability, beautiful appearance and high tracking accuracy. It is a new generation satellite communication antenna. This manual is applicable for the follow models of antenna: SCB37-110: C-Band Cassegrain 11 meters antenna for Circular or Linear Polarization; SCB : Ku-Band Cassegrain 11 meters antenna for Linear Polarization; SCB107E-110: Extend Ku-Band Cassegrain 11 meters antenna for Linear Polarization; 2

4 2 Technical Specifications 2.1 Specifications of the model SCB37-110: Electrical Performance Frequency Range Rx 3625 to 4200 MHz Tx 5850 to 6425 MHz Polarization Linear or Circular Gain Rx 51,4 dbi 4,00 GHz) (Including Losses) Tx 54,9 dbi 6,00 GHz) Half-power Beamwidth Rx 0,55º 4,00 GHz) Tx 0,35º 6,00 GHz) 10º El 42 K (@ 4,00 GHz) Noise Temperature 20º El 36 K (@ 4,00 GHz) 30º El 33 K (@ 4,00 GHz) Typical G/T, 20º elevation at clear Sky with C Band LNA, 30 K 33,0 db/k (@ 4,00 GHz) Anatel Resolution 572 Radiation Pattern Envelope FCC regulation ITU-RS580 Axial Ratio Rx 1.06 (0,5 db) (Circular Configuration) Tx 1.06 (0,5 db) Cross Polarization Discrimination Rx 35 db (Linear Configuration) Tx 35 db VSWR (Return Loss) Rx 1.3 (17.7 db) Tx 1.3 (17.7 db) Port to Port Isolation TX/RX 75 db RX/TX 55 db Feed Termination (flange) Rx CPR 229G Tx CPR 137 G Input Maximum Power 2000 W Mechanical Characteristics Diameter 11 meters Antenna Geometry Cassegrain Motion Elevation over azimuth Azimuth ± 90º Motion Adjustment Elevation 0 a 90º Polarization ± 50º Reflector Material Aluminum Mount Material Steel Finishing Reflector White painting Mount Hot dip galvanized Surface Precision 0.5mm (RMS) Environmental Characteristics Operational Wind 130 km/h Survival Wind 198 km/h Shock and Vibration Typical in sea, air and terrestrial shipments Atmosphere Found in seashore and industrial areas 3

5 2.2 Specifications of the model SCB : Electrical Performance Frequency Range Rx to MHz Tx to MHz Polarization Linear Gain Rx 61,1 dbi 12,00 GHz) (Including Losses) Tx 62,4 dbi 14,00 GHz) Half-power Beamwidth Rx 0,14º 12,00 GHz) Tx 0,12º 14,00 GHz) 10º El 60 K (@ 12,00 GHz) Noise Temperature 20º El 50 K (@ 12,00 GHz) 30º El 46 K (@ 12,00 GHz) Typical G/T, 20º elevation at clear Sky with C Band LNA, 60 K 40,5 db/k (@ 12,00 GHz) Anatel Resolution 572 Radiation Pattern Envelope FCC regulation ITU-RS580 Cross Polarization Discrimination Rx 35 db Tx 35 db VSWR (Return Loss) Rx 1.3 (17.7 db) Tx 1.3 (17.7 db) Port to Port Isolation TX/RX 75 db RX/TX 55 db Feed Termination (flange) Rx WR 75 Tx WR 75 Input Maximum Power 1000 W Mechanical Characteristics Diameter 11 meters Antenna Geometry Cassegrain Motion Elevation over azimuth Azimuth ± 90º Motion Adjustment Elevation 0 a 90º Polarization ± 50º Reflector Material Aluminum Mount Material Steel Finishing Reflector White painting Mount Hot dip galvanized Surface Precision 0.5mm (RMS) Environmental Characteristics Operational Wind 130 km/h Survival Wind 198 km/h Shock and Vibration Typical in sea, air and terrestrial shipments Atmosphere Found in seashore and industrial areas 4

6 2.3 Specifications of the model SCB107E-110: Electrical Performance Frequency Range Rx to MHz Tx to MHz Polarization Linear Gain Rx 60,6 dbi 11,45 GHz) (Including Losses) Tx 62,1 dbi 13,50 GHz) Half-power Beamwidth Rx 0,17º 11,45 GHz) Tx 0,14º 13,50 GHz) 10º El 60 K (@ 11,45 GHz) Noise Temperature 20º El 50 K (@ 11,45 GHz) 30º El 46 K (@ 11,45 GHz) Typical G/T, 20º elevation at clear Sky with C Band LNA, 60 K 40,0 db/k (@ 11,45 GHz) Anatel Resolution 572 Radiation Pattern Envelope FCC regulation ITU-RS580 Cross Polarization Discrimination Rx 35 db Tx 35 db VSWR (Return Loss) Rx 1.3 (17.7 db) Tx 1.3 (17.7 db) Port to Port Isolation TX/RX 75 db RX/TX 55 db Feed Termination (flange) Rx WR 75 Tx WR 75 Input Maximum Power 1000 W Mechanical Characteristics Diameter 11 meters Antenna Geometry Cassegrain Motion Elevation over azimuth Azimuth ± 90º Motion Adjustment Elevation 0 a 90º Polarization ± 50º Reflector Material Aluminum Mount Material Steel Finishing Reflector White painting Mount Hot dip galvanized Surface Precision 0.5mm (RMS) Environmental Characteristics Operational Wind 130 km/h Survival Wind 198 km/h Shock and Vibration Typical in sea, air and terrestrial shipments Atmosphere Found in seashore and industrial areas 5

7 3 Structural Character and Operational Principle 3.1 System Structural Character The 11m limit-motion antenna system is composed of antenna feed subsystem and structure subsystem. The antenna feed subsystem contains feed and main reflector and subreflector curves. The structure subsystem contains main reflector and subreflector, polarization rotation device, pedestal and antenna feeder. The composition principles of antenna system are shown in Fig The picture is shown in Fig Fig Composition Principle Block Diagram of Antenna System 6

8 Fig Picture of 11m antenna Antenna Structural Character Antenna Reflector Assembly The antenna reflector is mainly composed of main reflector, subreflector, backups, subreflector supporting device, feed sleeve, etc. The three-dimensional forming diagram is shown in Fig Fig Structural Schematic Diagram of 11m Antenna 7

9 Main Reflector Design The main reflector is one of the core components of the antenna system. Its theoretical curved surface is formed by synthetic curve rotating around the axis of the antenna. The antenna reflector is divided into multiple plates because of cumulative materials, manufacturing engineering, final assembly adjustment, etc. The reflector is divided into two rings. Inner ring reflector is divided into 20 same sector unit plates and the outer ring is divided into 20 sector unit plates. So the main reflector of antenna is composed of 40 reflector units. The stretched and shaped 2A12-O aluminum board with thickness of δ=2mm is used as individual sector plate after quenching, stretching and shaping. Z type aluminum casting material is used as back rib after quenching, stretching and shaping in order to perform positioning with rivet the die table for riveting rib and reflector. Each sector plate is supported at backups via 6 stretching bolts. In order to ensure the process precision, such process technology as first bonding and second riveting is adopted to improve the strength of individual plate and reduce the number of rivets and thus decrease the local deformation of plate caused by riveting points. The high precision mould and tool set up process are used for all procedures, such as stretching, stretch bending, riveting. The accuracy of the individual plate is 0.25mm (R.M.S). The reassembly precision of whole main reflector is 0.45mm (R.M.S) Subreflector and Its Supporting Mechanism Design The subreflector is made of aluminum casting material and adopts the integral structure. It is manufactured with the numerically controlled machine tool to ensure its precision, which is not more than 0.15mm (R.M.S). The subreflector supporting mechanism is composed of four support rods and one adjustment mechanism. In order to reduce its shadow to the main reflector and ensure the supporting rigidity, the subreflector support rod adopts the flat oval steel tube, of which one end is supported at the main backups and the other is connected with the subreflector through adjusting mechanism. The four adjusting bolts of adjusting mechanism are used to implement the adjustment of subreflector axial movement, lateral movement and drift angle. The three-dimensional forming diagram of subreflector and its supporting mechanism is shown in Fig

10 Fig Three-dimensional Diagram of Subreflector and Supporting Mechanism Reflector Backups Design The backups are the main stressed component and structural support of the whole antenna reflector. It adopts space reticular truss structure, of which various structural parts have such advantages as goodish consistency, smooth stress transmission, uniform stress, favorable manufacture and installation, etc. and are widely applied because of the higher rigidity-weight ratio. The backups consist of the HUB, radiating beams and hoop stress bars and diagonal bars. It is divided 20 pieces of main radiating beams along circumferential direction, a space pull bar is laid between two radiating beams. The diagonal bars are laid between the outer surface radiating beams. The previous bars parts constitute the space reticular truss structure, as shown in Fig Fig Reflector Backups Schematic Diagram 9

11 The HUB is the basic stressed component in the antenna structure and also the connection component between the antenna reflector and antenna pedestal. All loads of antenna reflector are down-transferred concentratively through the HUB. So the HUB must have higher rigidity. The appearance design of HUB is tapering barrel type, the bottom diameter is φ4300mm, the height is 1600mm, the coning angle is 76. The tapering barrel is made of steel plate (t=8), the top and bottom (t=10) are seal-welded with flange. 28 heterotypic ribs are in the corresponding positions of the HUB and radiating beams. One ring and two rings of concentric circular rib plates with the height of 200mm are respectively at the top and the bottom, so the cellular structure is formed in the whole HUB to make it have maximum rigidity. The polyphenyl heat insulating material with thickness of 50mm is stuck in the tapering barrel of HUB to constitute the high frequency room after built-in of fireproofing decorative plates for installation of general equipment and high frequency receiving components, of which minimum available volume is φ and which has larger and comfortable environment space. In order to meet the requirement of transportation, the HUB is designed as bilateral symmetry connection type, the thickness of connection steel plate is 16mm, the material type is Q235A, the fastener is M20 high intensity bolt, as shown in Fig The radiating beams is one of the main stressed components in the antenna reflector space reticular truss structure. It is the planar truss constituted by top boom, low boom, normal web member and diagonal web member through spherojoint welding. Its main role is to form the supporting back bracket of the main reflector of antenna with hoop stress pull bar and diagonal draw bar. The top boom and low boom are made of 20# steel material and they are seamless steel tubes with size of φ The normal web member and diagonal web member are made of 20# steel material and they are seamless steel tubes with size of φ50 3. Their characteristics are simple type, uniform stress, high rigidity and convenient surface treatment, as shown in Fig

12 Fig Schematic Diagram of HUB Fig Schematic Diagram of Radiating Beams The hoop stress pull bar is the steel pole fitting of φ50 3. The 3 hoop stress pull bars and diagonal draw bars are connected from beginning to end to the outer end of the radiating beams to play the role of hoop stress stabilization for the reflector framework. The material is 20# steel Feed Sleeve The feed sleeve is the supporting component of feed network, which is divided into two segment such as upper segment and lower segment. Both are formed through rolling and welding of Q235A steel plate with thickness of 4mm. The lower segment uses circular sleeve structure and moving sleeve design, microwave network is installed in the moving sleeve, which performs moving connection with fix sleeve through two thin wall bearing, the fix 11

13 sleeve is fixed in the HUB. The upper segment uses tapering sleeve structure, of which the upper end surface performs positioning connection with corrugated horn and the lower end surface performs positioning with the rabbet of moving sleeve and the flanges are connected with bolts. So, the linear polarization direction of feed network can be adjusted only by rotating moving sleeve for implementing linear polarization surface adjustment which uses electric mode Antenna Pedestal Structure The antenna pedestal is mainly used to provide the support for the antenna, and make the antenna perform the azimuth and elevation rotation and align the satellite accurately under the control of servo equipment. The antenna pedestal adopts the columnar beams type pedestal structure, namely A, E two axes type pedestal, it consists of pedestal, azimuth-elevation driving, synchronization and limit devices, platform ladder, etc. The structural three-dimensional modeling view is shown in Fig Fig m Antenna Pedestal 3D Modeling View Its azimuth driving mechanism is below columnar beams and the elevation driving mechanism is postposition type. The whole antenna pedestal is seated on five reinforced concrete bases. 12

14 Azimuth Part The azimuth part consists of the azimuth-elevation supporting combination, tripod, azimuth lower bearing pedestal combination, azimuth upper bearing pedestal combination, etc. The azimuth-elevation supporting combination is a T-type combination constituted by the kingpost with Ф900mm and tripod. The kingpost with length of 3.45m is decumbent on the previous one. The tripod is constituted with three inclined struts that their upper ends are converged at one point. The lower ends of the three inclined struts are fixed at the base with bolts, and the upper ends are connected to the azimuth upper bearing pedestal combination and fixed at the intersection point of their center connecting lines to form the upper axle head for azimuth rotation. The lower bearing pedestal combination is fixed at the base with bolts, the centers of the upper and lower bearing are at the same plumb line and form the azimuth axis. The annular contact thrust spherical-roller bearing is installed in azimuth lower bearing pedestal, the knuckle sliding bearing is installed in azimuth upper bearing pedestal. The upper and lower axle heads are respectively installed into the upper and lower rotation axle pedestal holes. In this way, the azimuth-elevation bearing combination can perform azimuth movement under the role of the azimuth driving device, the azimuth travel range is within ±90º Elevation Part The elevation part mainly consists of the azimuth-elevation bearing combination, driving pedestal E, elevation bearing pedestal combination, etc. On the support arms at the two sides of decumbent cylinder at the top of azimuth-elevation bearing combination, there is a pair of axle holes orthogonal with the azimuth axis, in which are the bearings. The two axle holes connect the elevation bearing pedestal combination with the decumbent cylinder via the clevis pin with head to form the elevation axis E. In this way, the antenna can perform the elevation movement under the role of elevation driving device. The elevation rotation range is within 0º~90º. 13

15 Driving Device The driving device consists of the elevation driving device and azimuth driving device. The driving device composition block diagram is shown in Fig The azimuth and elevation driving devices are lead screw type. The decelerator of driving device adopts SG-71 type plane secondary envelope worm pair. The decelerator adopts cycloid pin wheel decelerator and planetary gear decelerator. Fig Driving Device Composition Block Diagram AC motor: select and use double-speed AC motor, the type number is YD160L-16/4H (horizontal type), it is the sealed type three-proof motor, normal power is 2KW/8KW; rotating speed is 361r/min/1460r/min, the azimuth and elevation motor are same. Elevation decelerator: planetary gear decelerator, the type number is NGW11-9 (horizontal type), deceleration ratio: i=7.1. Azimuth decelerator: cycloid pin wheel decelerator, the type number is XW /9, deceleration ratio: i=9. Worm gear-worm pair: SG-71-type plane secondary enveloping surface torus worm pair, the worm is single-head type, deceleration ratio: i =40, the azimuth and elevation worm gearworm pairs are same. Lead screw-nut pair: the screw thread parameter is Tr150X14, the azimuth and elevation lead screw- nut pairs are same. The final stage of driving chain is lead screw-nut pair, which has self-locking capability. The antenna can apply the brake safely at any position and at the same time the nut pair use double nuts for backlash elimination Synchronization Device The azimuth and elevation synchronization devices are respectively installed on the azimuth and elevation axle heads, the corners of axis is transformed into the electrical signals and output to obtain the position information of antenna. 14

16 Limit Device In order to make the antenna rotate within the safe range, install safe limit protection device on the azimuth and elevation axle heads of antenna to make the antenna operate safely. The limit device consists of the limit switch and mass. The limit swicths are respectivily installed on the two extreme positions of travel range of azimuth and elevation axes, when the antenna travels the extrem position and the mass touches switch, the power supply is switched off Platform and Ladder For the convenience of maintenance and ensuring safeguard, the guardrail, ladder and platform are installed on the antenna pedestal Feed Structure The feed is the core of the whole antenna and its performances directly affect the RF performance of the antenna. So the optimized scheme and design should be performed more carefully. The feed is composed of corrugated horn and microwave network Corrugated Horn Rx and Tx singles of the antenna share the same corrugated horn. It s required to realize ideal radiation at the Rx and Tx bands, with rotary symmetry and low cross polarization radiation pattern and low VSWA characteristic. The corrugated horn consists of input taper section, mode converter section, transition section and output flare section. The transition section may include frequency transition section and angle transition section. If the frequency band is narrow, there is no frequency section. The principle block diagram is shown in Fig The purpose of the mode converter section is to well convert the main mode TE 11 in the circular waveguide into the main HE 11 in the corrugated waveguide, at the same time, maintain good match and reject the generation of the harmful high order mode EH 12. The transition section is to accomplish the transition of frequency and the angle between the mode converter section and the output flare section, at the same time, reject the generation of the harmful high order mode EH 12. The output flare section is to generate the required subreflector brim illumination level. The mode converter section is the key design. The ring-loaded slots in the mode converter section are adopted to expand the frequency band. The structural figure of the whole horn in C-band and Ku-band is shown in Fig and Fig , respectively. 15

17 Fig Corrugated Horn Block Diagram Fig Structural figure of corrugated horn in C-band Fig Structural figure of corrugated horn in Ku-band 16

18 3.2 Antenna Operation principle The C-band or Ku-band 11m Cassegrain antenna can be supplied with two ports (RX/TX) or four ports (2TX/2RX). The operation principles are described as follows. Antenna receiving principles:the antenna aligns satellite, the satellite signals are transmitted via main reflector and subreflector to the feed, then output from the corresponding port of feed and finally sent to the tracking receiver after LNA amplification. Antenna transmitting principles: the transmitting signals are sent from HPA to the feed via waveguide and radiated by the feed, then reflected to the free space via main reflector and subreflector of antenna and propagated to satellite. The antenna can simultaneously transmit and receive electromagnetic wave signals. The step tracking mode (optional) is used to make the antenna be able to align the satellite. 4 Maintenance As outdoor equipment, the antenna is exposed to natural environment such as wind, rain and sun. The life of the equipment is greatly affected by correct operation and maintenance. High-quality maintenance in time is very important to guarantee the service life of the equipment. To ensure the service life of the outdoor equipment, follow the requirements described below for operation and maintenance. 4.1 Operation and Maintenance of Antenna a) Pay attention to the local weather forecast. When strong wind higher than 32m/s is coming, make preparations in advance so as to lock the antenna toward the sky with pin at any time. b) Once the subreflector has been installed and adjusted well and put into use, nobody is allowed to go up onto the subreflector support. If it is necessary to go onto it for maintenance, it is prohibited to step on the subreflector to prevent the installation 17

19 accuracy of the subreflector from being changed. c) The main reflector is made of aluminum plates. The maintenance person isn t allowed to wear shoes with hard soles to avoid damaging the main reflector. d) Check regularly the thin seal film on the horn mouth surface. If there s any leakage, replace it in time or the normal operation of the antenna will be affected. e) The feed network and wave-guide components adopt rigid connections. Impact and crush are prohibited. f) Paint regularly. Spray three-proofing paint onto the antenna once every three years. g) Check if the components of the antenna have been installed correctly and reliably before startup. Eliminate the fault symptoms in time if there s any. h) Check regularly the seal cover of the synchronization device and check if all connection points of all cables are sealed. Seal the exposed part with sealant to prevent water leakage which causes short circuit or makes the equipment burned. i) When the antenna azimuth operation range changes and requires changing the section, it is recommended the wind speed be Grade 1~2 and not exceed Grade 3~4 at most. The position where the section is changed should enable the AZ leading screw to pass the position of the front support rod of the tripod, that is at AZ 100 or 260. Generally 4~5 persons are needed for section changing and one person takes command. The connector bolts of 6 M30 AZ drive leading screws are taken down, then the AZ drive and the antenna AZ are pushed to rotate to reach AZ 260 or 100 and connector bolts of 6 M30 AZ drive leading screws are reinstalled. j) Check and maintain the antenna pedestal regularly (three months is appropriate). Be careful to cut off the power to ensure human and equipment Safety during routine check and maintenance of the antenna pedestal. Make the following checks: Check regularly the AZ left and right limit the EL up and down limit.remove the failure in time if there s any to prevent such cases as that the limit cannot function when necessary, thus preventing serious accidents. Check regularly if the motor and the synchronization device are in good condition and sealed to prevent open circuit or short circuit leading to accident. Check regularly if the exposed screws are fixed well and screw down the loose ones in time if there s any. Check regularly if the lacquer coat has been damaged. Paint the damaged coat in time 18

20 (with zinc chromate primer and white polyurethane enamel. Check frequently all structural parts and rotating parts (shaft, bearing, leading screw, worm gear reducer, planetary reducer and cycloid pinwheel reducer). Resolve the problem in time if there s any. k) Overhaul of Antenna Pedestal ( the equipment should be stopped, once every three years) Check if all parts and components are damaged. Replace the damaged one in time if there s any. Clean, derust and oil all moving parts to guarantee flexible movement. Clean and adjust the axis, bearing, leading screw, worm gear reducer, planetary reducer and cycloid pinwheel reducer. Replace the damaged or nearly damaged component in time and apply enough lubricant (the lubricant grease is MnS2 EP lithium grease, the oil is high-grade heavy-duty gear oil) at the same time to ensure flexible movement. The lubricant grease and oil should be filled as described in (q). The grease and oil must be filled sufficiently, missing and inadequacy will cause serious results and the moving parts will be damaged in short time. Painting: spray paint in an all-round way once every three years. Clean the original lacquer coat before painting, then paint it with zinc chromate primer as required (once to twice) and white polyurethane enamel (twice to three times as required). l) There re two levels of moving speed of the antenna: fast and slow. The fast level is used for antenna section changing, stowing and satellite searching and the slow level for tracking satellite in normal operation. m) In case of natural disasters such as windstorm and earthquake, check the equipment constantly and replace the damaged parts and components in time. n) When the wind speed has reached the speed to stow the antenna, if extremely strong wind above Grade 10 is forecast (consider the wind speed at that time according to the forecast), rotate the antenna 2 hours in advance to the stowing position facing the sky. o) The leading screw cover is used to protect the leading screw. If damaged, repair or replace it immediately. p) Check the shaft, bearing, leading screw, worm gear reducer, planetary reducer and cycloid pinwheel reducer once every three months and apply lubricant (the grease is MnS2 EP lithium grease, the oil is high-grade heavy-duty gear oil) at the same time to ensure flexible movement. The method is: Apply lubricant grease to the AZ and EL reducer box. Take down the organic 19

21 glass plate from the box, then fill up with mushy lubricant mixed by MnS2 EP lithium grease and high-grade engine oil. Smear the AZ and EL leading screw with MnS2 EP lithium grease. The method is: open the leading screw protection cover and smear the leading screw thread surface with grease uniformly. Fill the oil cups of the AZ and EL rotating axles with MnS2 EP lithium grease (or mixed with high-grade engine oil to be mushy grease) using pressing oil gun to lubricate the rotating axles. Lubricate the planetary reducer and the cycloid pinwheel reducer. The method is to fill the grease hole with heavy-duty gear oil. 4.2 Operation and Maintenance of Servo Equipment a) Don t turn on and turn off the power switches frequently to prevent the components inside the cabinet from being damaged. b) Hot-plug is prohibited to prevent the equipment or peripheral components from being damaged and prevent malfunction. c) Be careful to set parameters in system menu. Don t modify the parameters rashly. Don t modify the system parameters, check them regularly. Once they are found to have been changed, restore them to the original value in time. d) Hot-plug may damage the equipment. 20