MANUAL FOR MODELS: SCB37-180 SCB107-180 SCB107E … SCB37-180.pdf · MANUAL FOR MODELS: SCB37-180 SCB107-180 SCB107E-180 18 METERS CASSEGRAIN EARTH STATION ANTENNAS . 3 ... 3.2 Antenna

MANUAL FOR MODELS:

SCB37-180

SCB107-180 SCB107E-180

18 METERS CASSEGRAIN EARTH STATION ANTENNAS

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C o n t e n t 1 General………………………………………………………………………………...2 2 Technical Specifications………………………………………………………………3 2.1 Specifications of the model SCB37-180…………………………………………….3 2.2 Specifications of the model SCB107-180…………………………………………...4 2.3 Specifications of the model SCB107E-180………………………………………….5

3 Structural Character and Operational Principle………………………………………..6 3.1 System Structural Character...................................................................…..................6 3.1.1 Antenna Structural Character..………………………………………….……….7 3.1.2 Antenna Pedestal Structure…..…………………………………………………13 3.1.3 Feed Structure…..………………………………………………………………15

3.2 Antenna Operation Principle..................................................................................... 17

4 Maintenance..............................................................................................................….17

4.1 Operation and Maintenance of Antenna.............…............ .....................…............. 17 4.2 Operation and Maintenance of Servo Equipment......................................…............ 20

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1 General

The 18m antenna, a synthetic Cassegrain dual-reflector antenna models SCB37-180,

SCB107-180 and SCB107E-180, 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:

SCB37-180: C-Band Cassegrain 18 meters antenna for Circular or Linear Polarization;

SCB107-180: Ku-Band Cassegrain 18 meters antenna for Linear Polarization;

SCB107E-180: Extend Ku-Band Cassegrain 18 meters antenna for Linear Polarization;

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2 Technical Specifications

2.1 Specifications of the model SCB37-180:

Electrical Performance 3625 to 4200 MHz

Frequency Range Tx 5850 to 6425 MHz

Polarization Linear or Circular Rx 55,7 dBi (@ 4,00 GHz) Gain

(Including Losses) Tx 59,2 dBi (@ 6,00 GHz) Rx 0,3º (@ 4,00 GHz)

Half-power Beamwidth Tx 0,2º (@ 6,00 GHz)

10º El 42 K (@ 4,00 GHz) 20º El 36 K (@ 4,00 GHz) Noise Temperature 30º El 33 K (@ 4,00 GHz)

Typical G/T, 20º elevation at clear Sky with C Band LNA, 30 K

37,3 dB/K (@ 4,00 GHz)

Anatel Resolution 572 FCC regulation 25.209 Radiation Pattern Envelope

ITU-RS580 Rx 1.06 (0,5 dB) Axial Ratio

(Circular Configuration) Tx 1.06 (0,5 dB) Rx 35 dB Cross Polarization Discrimination

(Linear Configuration) Tx 35 dB Rx 1.3 (17.7 dB)

VSWR (Return Loss) Tx 1.3 (17.7 dB)

TX/RX 75 dB Port to Port Isolation

RX/TX 55 dB Rx CPR 229G

Feed Termination (flange) Tx CPR 137 G

Input Maximum Power 2000 W

Mechanical Characteristics Diameter 18 meters

Antenna Geometry Cassegrain Motion Elevation over azimuth

Azimuth ± 90º Elevation 0 a 90º Motion Adjustment

Polarization ± 50º Reflector Material Aluminum Mount Material Steel

Reflector White painting Finishing

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

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2.2 Specifications of the model SCB107-180:



Polarization Linear Rx 65,2 dBi (@ 12,00 GHz) Gain





44,3 dB/K (@ 12,00 GHz)


ITU-RS580 Rx 35 dB

Cross Polarization Discrimination Tx 35 dB Rx 1.3 (17.7 dB)



RX/TX 55 dB Rx WR 75

Feed Termination (flange) Tx WR 75











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2.3 Specifications of the model SCB107E-180:



Polarization Linear Rx 64,8 dBi (@ 11,45 GHz) Gain





43,90 dB/K (@ 11,45 GHz)


ITU-RS580 Rx 35 dB

Cross Polarization Discrimination Tx 35 dB Rx 1.3 (17.7 dB)



RX/TX 55 dB Rx WR 75

Feed Termination (flange) Tx WR 75











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3 Structural Character and Operational Principle

3.1 System Structural Character The 18m full-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.3.1-1. The picture is shown in Fig.3.1-2.

Fig.3.1-1 Composition Principle Block Diagram of Antenna System

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Fig.3.1-2 Picture of 18m antenna 3.1.1 Antenna Structural Character

3.1.1.1 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.3.1-3.

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Fig.3.1-3 Structural Schematic Diagram of 18m Antenna

3.1.1.2 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 four rings. Inner ring

reflector is divided into 16 same sector panels and the rest are divided into 32 sector panels.

So the main reflector of antenna is composed of 112 panels.

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).

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3.1.1.3 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.3.1-4.

Fig.3.1-4 Three-dimensional Diagram of Subreflector and Supporting Mechanism

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3.1.1.4 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 32 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.3.1-5.

Fig.3.1-5 Reflector Backups Schematic Diagram

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.

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The appearance design of HUB is tapering barrel type, the bottom diameter is φ5500mm,

the height is 1910mm, the coning angle is 73°. The tapering barrel is made of steel plate (t=8),

the top and bottom (t=10) are seal-welded with flange. 32 heterotypic ribs are in the

corresponding positions of the HUB and radiating beams. All 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 5500 × 1910 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.3.1-6.

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 57 × 3. 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.3.1-7.

Fig.3.1-6 Schematic Diagram of HUB

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Fig.3.1-7 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.

3.1.1.5 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

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.

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3.1.2 Antenna Pedestal Structure The antenna pedestal adopts the elevation over azimuth full-motion mount structure, mainly

composed of azimuth king-post, azimuth box, elevation box, left/right support arms, elevation

lock device, azimuth/elevation driving device, azimuth/elevation bearing, operation platform

and ladder, etc. The structural three-dimensional modeling view is shown in Fig.3.1-8.

Fig.3.1-8 18m Antenna Pedestal 3D Modeling View

3.1.2.1 Azimuth Part The azimuth part mainly consists of azimuth king-post, azimuth box, large azimuth bearing,

azimuth driving device, cable winding device, limit and angle measuring device, etc. The azimuth drive uses dual drive chains and electric anti-backlash drive. The azimuth

king-post and turntable use steel plates that are welded into cavity structure, there is large

space in the inner cavity where the driving system, cable winding device, limit and angle

measuring device and lock device, etc. are placed. The azimuth rotation range is within ±165º.

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3.1.2.2 Elevation Part The elevation part mainly consists of elevation box, left/right support arms, driving system,

limit device and angle resolver device, buffer, lock, counterweight and operation platform and

ladder, etc. The elevation drive also uses dual drive chains and electric anti-backlash drive. The elevation

box and left/right support arms use steel plate welded structure. The elevation rotation range

is within 0º~90º.

3.1.2.3 Driving Device

The driving device is used for driving the antenna to align satellite. The antenna driving

system is divided into two parts i.e. azimuth driving device and elevation driving device. The

azimuth driving device and elevation driving device have the same composition, both use

dual-motor clearance driving mode, and have dual drive chains, each of which consists of

motor, planetary gear decelerator and final-stage large gear. The method of using dual drive

chains has the following advantages: using electric anti-backlash drive method to eliminate

backlash and improve the system point and track precision, at the same time, reducing the

volume of driving box and increasing the rigidity of driving system. The driving device composition is as shown in Fig.3.1-9.

Fig.3.1-9 Block Diagram of Driving Device 3.1.2.4 Synchronization Device

The synchronization device transforms the rotating angles of axes into the electrical signals

and obtains the position information of antenna. It is mounted on the azimuth and elevation

axes of antenna by using sleeve shaft mode so as to meet the requirements of information

transmission and transformation.

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3.1.2.5 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.

3.1.2.6 Platform and Ladder

For the convenience of maintenance and ensuring safeguard, the guardrail, ladder and

platform are installed on the antenna pedestal.

3.1.3 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.

3.1.3.1 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.3.1-10. The purpose of the mode

converter section is to well convert the main mode TE11 in the circular waveguide into the

main HE11 in the corrugated waveguide, at the same time, maintain good match and reject the

generation of the harmful high order mode EH12. 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 EH12. 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

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adopted to expand the frequency band. The structural figure of the whole horn in C-band and

Ku-band is shown in Fig. 3.1-11 and Fig. 3.1-12, respectively.

Fig. 3.1-10 Corrugated Horn Block Diagram

Fig. 3.1-11 Structural figure of corrugated horn in C-band

Fig. 3.1-12 Structural figure of corrugated horn in Ku-band

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3.2 Antenna Operation principle

The C-band or Ku-band 16m 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

accuracy of the subreflector from being changed.

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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

(with zinc chromate primer and white polyurethane enamel.

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• 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

glass plate from the box, then fill up with mushy lubricant mixed by MnS2 EP lithium

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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.

Documents

MANUAL FOR MODELS: SCB37-180 SCB107-180 SCB107E … SCB37-180.pdf · MANUAL FOR MODELS: SCB37-180 SCB107-180 SCB107E-180 18 METERS CASSEGRAIN EARTH STATION ANTENNAS . 3 ... 3.2 Antenna