satellite antenna testing

8/17/2019 Satellite Antenna Testing

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AMTA Europe Short Course 2004

1


Satellite Antenna Testing

Presented by

Dr. Jürgen Hartmann

EADS Astrium

Measurement Technology

81663 Munich – Germany

+49 89 607 22420

[email protected]


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Contents

1. Introduction

2. Test Facilities

- Range Trade-Off - Range Comparison

- Compact Test Range

3. Description of EADS Astrium CCRs

- Facility Heritage- Illumination System

- Feeds

- Instrumentation

4. Measurement Applications

- Antenna Pattern and Gain Measurement Setup

- Intelsat-IX C-Band Antenna Testing

- Payload Measurements

5. Conclusion


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3

Introduction

State-of-the-Art Communication Satellite Antennas:

Multiple Beams: Multi-Feed and/or Shaped Reflector Antennas

Multiple Frequencies and Polarizations

Requirements for Antenna Testing:

Time Efficient Measurements

Highly Accurate Measurements

Examples: 1984 German TV-SAT: 1 Beam, 5 Frequencies, 2 Pol.

6 Weeks

1996 Intelsat 8: 8 Beams, 10 Frequencies, 2 Pol.

2 Weeks


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4

Test Facilities

• Range Trade-Off

– Far-Field Range

– Near-Field Range – Compact Test Range

Range Comparison

• Compact Test Range

– Concepts

– Limitations – Plane Wave Quality

Compensated Compact Range (CCR)


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5

Test Facilities

Scenario for Communication Satellite Antennas


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Range Trade-Off Range Comparison

Far-Field Range

Advantage

• No data transformation required

• Real time measurement

• Easy operation

Disadvantage

• Large measurement distance required!

• Ground reflections / interference!

• Weather dependence!

• Cleanroom requires Radom!

• Gravity Compensation for DUT

Dynamic range?

Measurement Accuracy?


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Range Trade-Off Range Comparison

Near-Field Range

Advantage• Accurate measurements (0.1 - 40 GHz)

• Short measurement distance < 5 m:• Low free space losses

• Low reflection sensitivity

• Indoor measurement range:

• Cleanroom conditions

• 24 hours / day operations• Low reflectivity

• Easy Gravity Compensation for DUT

Limitation / Disadvantage

• Near field measurements:• Fourier transformation required for

calculation of far field pattern

• No real-time Measurements

• Coupling between Probe and DUT

• Usable frequency range:

• Typically < 40 GHz limited byProbe Positioning Accuracy (Limits

Phase Measurement accuracy)


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Range Trade Off Range Comparison

Compact Range

Advantage• Direct far field measurement:

• No data transformation required• Real-time measurements

Easy operation

• Short measurement distance < 20m:

• Low free space losses

• Accurate measurements (1.5-200 GHz)

• Indoor measurement range:

• Cleanroom conditions

• 24 hours / day operations

• Low reflectivity

Limitation / Disadvantage• Usable frequency range:

• Typical < 500 MHz limited by

diffraction

• Typical > 200 GHz limited by

reflector surface accuracy• Feed / test-object direct coupling

• Gravity Compensation for DUT


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Range Trade-Off Compact Range Principles

Goal:• Test zone with constant amplitude

and phase behavior (plane wave)

Starting Point:• Source feed generating spherical

wave

Parabolic Reflector:• transforms phase front,

spherical wave => plane wave

(equal distances between source

feed and test zone results inconstant phase front)

• Amplitude remains almost

unchanged

Requirement:• Source generates uniform

amplitude

P l a

n e W a v e

&

T e s t Z o n e

Source Feed

(Spherical wave)

Offset Reflector System


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Single Reflector (Paraboloid)

Double Reflector (2 Cylinder Paraboloids)

Double Reflector (Hyperboloid + Paraboloid)

Comparison of Complexity:

1 reflector 2 reflectors 2 reflectors

double curvature single curvature double curvature


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Comparison of Compression Factors for comparable Test Zones:

1 : 1 1 : 2 1 : 4

Plane Wave Uniformity:Phase ++ Phase + Phase +

Amplitude -- / Asymm. Amplitude - / Asymm. Amplitude ++ / Symm.

Transforming Geometries of different Compact Range

Concepts


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Co-Polar

No

Cross-Polarization

-0.1 dB

-0.5

-0.1

-0.3

-0.2

-0.2 -0.1

-30

-30

-25

-25

-30 dB

-30

-27

-27

Cross-Polar

Single Reflector Dual Reflector (Single Curved) Dual Reflector (Double Curved)


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Conclusions:

1) Diffraction reduces Quiet Zone Size to approx. 80% of Main Reflector Dimensions2) Good Performance at 1.5 GHz requires at least 1.5m Serration Length

Two concepts

“Rolled

Edges”

“Serrated

Edges”21 21 2114 21

Case a) Case b) Case c)

Influence of Serrationlength on Plane Wave Performance

R e l . A

m p l i t u d e ,

d B

Width in Wavelength

Width in Wavelength

Case a)

b)

c)

P h a s e i n °


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Description of the Astrium CCRsFacility Heritage

CCR 75/60 CCR 75/60

CCR 75/60

CNTF: Cylindrical Near-Field Test Facility

CCR: Compensated Compact Range

SCR: Single Reflector Compact Range

BAeSystems

CNTF - 8

Turn Key

CCR 75/60

Turn Key

Alcatel

LMAS(closed)Astrium

EADS

Military

Aircraft

Astrium

EMSSSL

CNES

CCR 20/17

CNTF - 30Turn Key

CCR 75 /60

Munich

University

(FH)

CCR 20/17INTESPACE

CCR 75/60

Turn Key

P h o t o :

D S S

P h

o t o : D S S

P h o t o : D S S

P h o t o : S P A R

P h o t o : S S L

P h o t o : C N E S

P h o t o : S i e m e n s

P h o t o : A e r o s p a t i a l e

P h o t o : D A S A / D S S

MELCO

CCR 75/60

1985

1992

2004

P h o t o : K H I

KHI

SCR 50E

P h o t o : L M A S

P h o t o : D S S

P h o t o : D S S

ISRO

A/B

CCR 75/60

Turn Key

SCR 60

Measurement

Facility

Heritage

1995

P h o t o

: D S S

CCR 120/100

Turn Key

CAST

P h o t o : M E L C O

P h o t o : I N T E S P A C E


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Description of the Astrium CCRsCCR 75/60

Highly Accurate Antenna Testing required

EADS Astrium CCRs: CCR 75/60 (5 m QZ)

CCR 120/100 (8 m QZ)

Main Characteristics:

Dual Reflector System (Top Fed Cassegrain)

Double Curved Reflectors (Hyperboloid, Paraboloid)

Large equivalent Focallength (130 m, 237 m)

Low differential Pathloss

Fully Cross-Polar Compensated System


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Description of the Astrium CCRsCCR 75/60 at Astrium in Munich


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Description of the Astrium CCRsCCR 120/100 of EADS Astrium GmbH


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Geometrical Data of Reflectors

ReflectorParameter

Sub Main

Dimension (W x H) 5.6 x 5.3 m 7.5 + 1 x 6.0 m

excl. Serration,

BillboardFocal Length 30 m 40 m

Surface Accuracy 35µm RMS

35µm RMS

Serration Length 1.5 m 1.5 m

Number of Segments 2 4

Back Structure Depth 1.1 m 1.1 m

Mass 44 000 kg 77 000 kg


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Reflector Technology

Spherical Cast Iron Material

Milled by a 5-Axes Laser Controlled Milling Machine

Milling Steps and Tracks ~ 2 .. 3 µm

Few monolithic Segments enabling

Easy and fast Installation

Easy and high accurate Alignment

Highly Stiffened Supporting Structure

Good Thermal Conductivity of Segments

Long Term Mechanical Stability


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Technical Data CCR 75/60

Typical Data

Frequency Range 1.5 – 200 GHz

Quiet Zone Size (W x H x D) 5.5 x 5.0 x 8.0Quiet Zone Performance

Amlitude Ripple±

0.5 dB

Phase Ripple±

6 deg

Cross-Polar Level < - 40 dB

Measurement Errors

Sidelobes±

1 dB @ 35 dB

Gain±

0.25 dB Bore-Sight Accuracy

±

0.014 deg

Scanning Capability 10 deg

Scan Angle Accuracy±

0.0003 deg

f CC


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D i ti f th A t i CCR


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-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

-20 -15 -10 -5 0 5 10 15 20

R e l . F i e l d A m p l i t u d e [ d B ]

Azimuth Angle [deg.]

Comparison of Antenna PatternCustomer Test Facility Astrium CCR (Ottobrunn)

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

-20 -15 -10 -5 0 5 10 15 20

R e l . F i e l d A m p l i t u d e [ d B ]

Azimuth Angle [deg.]

Co-Polar Cross-Polar

Test Antenna: Elliptical C-Band Offset Reflector Antenna (Rx: 5.854 – 6.298 GHz)



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Description of the Astrium CCRsFeeds

CCR Feeds of EADS Astrium from 1.5 to 40 GHz

Description of the Astrium CCRs


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Performance Data

• 7 Dual Linear Polarized Feeds (CCR 75/60): 1.47 .. 18 GHz

• 2 Single Linear Polarized Feeds: 18 .. 40 GHz• Broadband Behavior: 27.. 40 % BW

• Medium Gain Horns: typ. 13.4 dBi

• Frequency Independent Radiation Pattern

• Amplitude Taper*: < 0.75 dB

• Phase Taper*: < 3.5 °

• Cross-Polarization*: < - 38 .. - 42 dB

• Return Loss: < - 15 .. - 18 dB

• Port to Port Isolation (Dual Pol. Feeds): < - 35 .. - 40 dB

• Insertion Loss: < 0.2 .. 0.5 dB

*within FoV:±

9 °



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Performed Measurements:

Co-Polar Pattern: 8 Cuts

Discrete Frequencies (3 / Band)

Amplitude and Phase (S21): 4 Cuts

Swept Frequency Mode



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Performed Measurements:

Cross-Polar Pattern: 8 Cuts

Discrete Frequencies (3 / Band)

Amplitude and Phase (S21): 4 Cuts Swept Frequency Mode



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Description of the Astrium CCRsInstrumentation

Agilent Measurement System HP85301B/C

– Receiver HP8530A

– Measurement Speed:400 µs per Data Point for Multiple Frequencies

– Synthesized Sources

– Distributed Frequency Converter

Fundamental Mixing up to 18 GHz Low Harmonic Mixing up to 40 GHz

– PIN Switches with < 1 µs Switching Speed

for Multiple Channel Measurement

for Dual Polarization Measurement

Improved System Dynamic

More Data Sampling in Less Time



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Frequency [GHz] 1,50 3,00 6,00 12,00 18,00 26,50 40,00

System Dynamic [dB] 80 72 64 73 66 71 58

(S/N=1, Avg=1) Avg=128 Avg=128

valid for a DUT Gain of 20.0 dBi

Typical Dynamic Range



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TTL Triggering Timing Diagram



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Description of the Astrium CCRsInstrumentation for Antenna Pattern Measurements

Receiver HP8530A

Mult. Ch. Controller HP85330A

HP85320B

HP85320B

LO/IF UnitHP85309A

LO/IF UnitHP85309A

HP85331A

Sy nthesizer HP83640L

Bus-Extender

HP37204A

HP8348A

RJ

Feed

HP87301D LNA Amplif ier

Feed - Room CCR

Synthesizer HP83621B

Cable

Duct

Operator - Room

RF Signal

LO Signal

IF Signal

1

23

4

10

118

27

22

23

24

Bus-Extender HP37204A

9


25

19

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2 x6 dB

20 dB

RJ

65

7

12Power Ampl.Supply

Rack

20

26Power Ampl.Supply

Rack

13

14

RJ

18

HP85332A

DUT

17

15

RJ

21

4 x6 dB

16



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Description of the Astrium CCRsInstrumentation for Antenna Gain Measurements

Receiver HP8530A

Mult. Ch. Controller HP85330A

HP85320B HP85320B

LO/IF UnitHP85309A

LO/IF UnitHP85309A

HP85331A

Sy nthesizer HP83640L

Bus-Extender

HP37204A

HP8348A

RJ

Feed

HP87301D LNA Amplif ier

Feed - Room CCR

Synthesizer HP83621B

Cable

Duct

Operator - Room

RF Signal

LO Signal

IF Signal

1

23

4

10

118

27

22

23

24


9


25

19

3028 31

2 x6 dB

20 dB

RJ

65

7

12Power Ampl.Supply

Rack

20

26Power Ampl.Supply

Rack

13

14

RJ

18

HP85332A

DUT

17

15

RJ

21

4 x6 dB

16

Power Head A

Reference

Power Head B1. Measurement

Power Meter

Power Head B2. Measurement

29

30 m

30 m

60 m

Power Measurement Method

Intelsat IX C Band Antenna Testing


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Intelsat-IX C-Band Antenna Testing

The INTELSAT-IX Scenario

– 7 Satellites for

Atlantic Ocean Region (AOR) Indian Ocean Region (IOR)

– EADS Astrium was awarded with the Contract for

16 C-Band Hemi-/Zone-Beam Antennas

– Separate C-Band Antennas for Transmit (TX) and

Receive (RX) case; one Set of spare Antennas

– Short Development Time

21 months for the 1st Flight Model

Delivery of one TX/RX antenna every 3 months

Efficient RF Test and Analysis Capability Required

Intelsat IX C Band Antenna Testing


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TX Antenna @ Compact

Range CCR75/60 of

Astrium

TX Feed Array



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(Cont’d)

• 8 Beams/Antenna with 7 fold frequency reuse require high

cross-pol. / spatial isolation between Beams (> 29 .. 33 dB)

• High Isolation (> 27 dB) and Gain Requirements (±

0.25 dB)

• Stringent EIRP (36 dBW) / G/T requirements

• Beam Forming Network with 3 Wave Guide Switches & up to

7 Coax Switches

• Contact-less RF interfaces between different layers of BFN

• Dual circular Polarisation: Each horn is individually tuned

• Broad operating temperature Range

– TX: -50°C to +90°C RX: -50°C to +78°C



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Azimuth

0°

0°-10°

10°

10°

-10°

E l e v a t i o n

E l e v a t i o n

Azimuth

0°

0°-10° 10°

10°

3.629 GHz RHCP-10°

Hemi Beams

Azimuth

0°

0°-10°

10°

10°

-10°

E l e v a t i o n

3.704 GHz LHCP

Azimuth

0°

0°-10°

10°

10°

-10°

E l e v a t i o n

Zone Beams

P PPPPPPPPPPP P

Hemi B Hemi A

Zone G

Zone D Zone B Zone C Zone F Zone A

Hemi B Hemi AZone D Zone AZone B/E Zone C/F/G

Zone E

Block Diagram(six out of nine beams used simeltaneously)

Transmit Beam Forming Network

Six-Fold Frequency Re-use

(Cont’d)



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(Cont’d)

Hemi Beams Zone Beams

Coverage Design



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(Cont’d)

Test Drivers

– Complex BFN structure with up to 145 SCRIMP horns

– Short development time

– Only one Protoflight Model (PFM) was foreseen

– Strict performance monitoring to detect any malfunction

at an early stage requires

Different Measurement Techniques


(C t’d)


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(Cont’d)

Test Flow

Beam Forming Network

Meas. @ BFN Level

Near Field Testing

@ Feed Level

Compact Range Testing

@ Antenna Level

Compact Range Testing

@ Spacecraft Level

at ambient (+20°C) and

extreme temperatures (+85°C,

-50°C) prior to and after the

environmental tests

with Mock-Up

structure

Prior to the

feed integration


(C t’d)


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(Cont’d)

1. Measure excitation coefficientsof BFN and calculate the

primary pattern

2. Calculate the spherical wave

expansion coefficients (SWE)

for every horn pattern

3. Calculate the secondary far field

pattern using a synthetic

reflector model

4. Compare with other types of

measurement and/or prediction

Processing Steps BFN - Upper Layer


(C t’d)


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(Cont’d)

-10.0 Azimuth 10.0

10.0

E l e v a

t i o n

-10.0

Copolar Gain Zone_3 at 3.625 GHz

O dB corr. to Spec.= 25.30 dBi, Max.: 5.98 dB

Comparison: BFN – Compact Range

Far Field Pattern of Zone 3, TX

Black: BFN

Red: Compact Range


(C t’d)


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(Cont’d)

1. Measure cylindrical near field of feed

array (BFN with mounted SCRIMPhorns) and calculate the primary

pattern

2. Calculate the spherical wave

expansion coefficients (SWE)

3. Calculate the secondary far field

pattern with a synthetic reflector

model

4. Compare results from different near

field measurements (ambient, hot(+85°C), cold (-50°C), prior to and after

environmental testing)

5. Compare with other types of

measurement and/or prediction

Processing Steps Cylindrical Near Field Range


(Cont’d)


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(Cont’d)

Comparison: Near Field – Compact Range

Far Field Pattern of Hemi 1, TX

Dotted: Near Field @ AmbientSolid: Compact Range


(Cont’d)


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(Cont’d)

1. Measure directly the secondary far

field pattern

2. Compare with other types ofmeasurement and/or prediction

Processing Steps

Spacecraft at CompactRange CCR 75/60 of

Space Systems/Loral


(Cont’d)


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(Cont d)

Comparison: Compact Range @ Unit Level – System Level

Far Field Pattern of Hemi 1, TX

Dotted: Unit Level TestingSolid: System Level Testing


(Conclusion)


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(Conclusion)

• Key Factors for Design and Manufacturing of Multiple

Beam Antennas

– Accurate Antenna Design and Modeling Software

– Precise Antenna Measurement Techniques

• Results

– Knowledge of Complex Excitation Coefficients sufficient for

Calculation of Secondary Far field Pattern – Highly Accurate Near Field Testing at extreme Temperatures

possible

– Monitoring and Performance Tracing along Manufacturing Process

possible

• Conclusion for INTELSAT-IX Project

– Successful time delivery of all C-Band Antennas

– All Satellites launched with successful In-Orbit Test performed

Conclusion


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Antenna Testing of State-of-the-Art Communication Satellites

requires

Highly Accurate Time Efficient

Key Factors:

Test Facility

Test Equipment & Instrumentation

Test Philosophy

Test Procedure

Test Personnel

Exemplary Test Campaign shown with INTALSAT-IX Antenna Testing

performed at EADS Astrium in Ottobrunn

Measurement Techniques

satellite antenna testing

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