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Advanced Antenna Systems for 21st Century

Satellite Communications Payloads

by

Dr. Sudhakar Rao, FIEEE

Distinguished Lecturer, IEEE APS

Technical Fellow, Electronics & Payloads Directorate

Northrop Grumman Aerospace Systems

Redondo Beach, CA 90278, USA

IEEE APS Distinguished Lecture 2015

“Approved for Public Release; NGAS 14-1018, 5/29/14”

S. Rao

Introduction to Satellite Communications

Contoured Beam Antennas

Multiple Beam Antennas

Multi-Band Antennas

Reconfigurable Beam Antennas

Hybrid Antennas

PIM, Multipaction, Test Methods

Conclusions

Pg.2

AGENDA

*S. Rao, L. Shafai, & S. Sharma, “Handbook of Reflector Antennas and Feed Systems”, Vol. 3, Artech House Publishers, June 2013

** S. Rao, “Advanced Antenna Technologies for Satellite Communications Payloads”, IEEE Trans. AP, Special Issue, Apr 2015

DL Talk: 2015

SYNCOM 2 TELSTAR

S. Rao

IEEE Introduction & Membership

Pg.3

• Student Member

• Member

• Senior Member

• Fellow

• Life Fellow

Membership grades: Who Qualifies for Student Membership?

• Undergraduate or graduate students

• 50% of a normal full-time course of study (at least part-time studies)

• Electrical, electronics or computer engineering, computer sciences

• An allied branch of engineering, engineering technology

or the related arts and science

• Student membership dues are 20% of regular memb ($30 vs $147)

• The IEEE is the largest professional society in the world. At present,

there are more than 460,000 members in about 175 countries.

• The IEEE and its predecessors date to 1884.

• The IEEE produces 30 percent of the world's published literature in

electrical engineering, computers and control technology.

• There are more that 1,200 student branches.

• There are 38 technical Societies + 10 Divisions & 10 Regions

DL Talk: 2015

The IEEE is largely a volunteer organization. Enhance your career by getting involved!

S. Rao

Introduction to SATCOM Antennas:

Definition of Satellite Communications

Pg.4

Satellite uses a space platform as a relay or broadcast node

Satellite serves as an information collection, management and dissemination center

with a relatively vast communications area compared to ground based relay networks

DL Talk: 2015

GEO Comm Satellites

GPS Intersatellite Link Content Data

Command Uplink

TLM Downlink

Direct Broadcast

Downlink

Intersatellite Relay Link

Mission Data

Downlink

LEO

S. Rao

Advantages of Satellite Based Communications

Pg.5

17.40

Only three or four satellites in

geosynchronous orbit are necessary to

provide near global coverage

One satellite for national/regional coverage

• Earth Radius = 6832 kms

• Satellite Altitude = 35786 kms

• Subtended Angle = +/- 8.70

Benefits of satellites over conventional ground media

(cable, wire, fiber, point-to-point) include:

– Fast development and establishment of a

communications infrastructure

– Higher availability

– Immediate coverage of desired area after launch

• Satellites do not respect natural limitations such as

mountains, water, etc. or political boundaries

– Distance insensitive for point-to-multi-point communications

• Fiber optic systems are optimal for point-to-point

connections with a limited number of distribution nodes

– Lower cost for 100% coverage of a region

• More cost effective for providing thin route services

Requires only 3 or 4 satellites for global coverage DL Talk: 2015

S. Rao Pg.6

GPS-3

AEHF

Pg.6

WGS

ACeS

Echo X

GEO Satellites

DL Talk: 2015

S. Rao

Designated Satellite Services (ITU)

Pg.7

Aeronautical Mobile Satellite Service (AMSS)

Aeronautical Radio Determination Satellite Services (ARDSS)

Amateur Satellite Service

Broadcasting Satellite Service (BSS)

Earth-Exploration Satellite Service (EESS)

Fixed Satellite Service (FSS)

Inter-Satellite Service (ISS)

Land Mobile Satellite Service (LMSS)

Maritime Mobile Satellite Service (MMSS)

Meteorological Satellite Services

Mobile Satellite Service (MSS)

Radio Determination Satellite Services (RDSS)

Space Operations Service

Space Research Service

Standard Frequency and Time Signal Satellite Service

Personal Communication Services (PCS)

DL Talk: 2015

S. Rao

Communications Satellite System Connectivity

Pg.8

UserContent

BasebandProcessing

• A/D Conv ersion• Data Compression• Multiplexing• Error Correction Encoding• Encryption

NetworkInterface

• Data Rate Control• Format Conv ersion• Protocol Conv ersion• User Access Control• Data Routing• Multiple Access

RFTransmitter

• RF Modulation• Frequency Translation• Signal Amplification

Transponder

Satellite

Free SpaceLosses

OtherLosses

TransmitChain

• RF Demodulation• Frequency Translation• Signal Condition

RFReceiver

NetworkInterface

• Data Rate Control• Format Conv ersion• Protocol Conv ersion• User Access Control• Data Routing

BasebandProcessing

• D/A Conv ersion• Decompress Data• Error Correction• Decryption• Demultiplex

ReceiveChain

OtherLosses

Free SpaceLosses

UserInterfaces

Satellite Payload

Transmit Antenna Receive Antenna

Downlink

Uplink

• RF Signal Reception

• RF Signal Transmission

GroundSegment

• Clear Air• Ra in• Waveform Distortion• Scintillation

Interference

Interference

DL Talk: 2015

S. Rao

Antenna Directivity, Gain, Polarization

Pg.9

Isotropic radiator

– A point source that radiates equally in all directions

Directivity

– A measure in dB of an antenna’s ability to transmit or receive energy in a given direction compared to an isotropic radiator.

Isotropic Radiator

Directive Antenna

Gain

= Directivity – Antenna Losses DL Talk: 2015

Vertical Horizontal Left Hand

Circular

Right Hand

Circular

• OMTs (symmetric, asymmetric)

• Polarizers

- 5 - 4 - 3 - 2 - 1 0 1 2 3 4

5

6

7

8

- 5 - 4 - 3 - 2 - 1 0 1 2 3 4

5

6

7

8

S. Rao

High Gain Antennas (30 dBi to 70 dBi)

- Reflector Antennas

- Lens Antennas

* Dielectric Lenses: ESD issues

* Waveguide Lenses: Narrow Bandwidth

- Array Antennas

Medium Gain Antennas (15 dBi to 25 dBi) -

Global coverage horns

Low Gain Antennas (0 dBi to 12 dBi) -

Biconical Antennas -

Waveguides - Horn

Antennas

Pg.10

Spacecraft Antenna Types

Dielectric Lens

Radiation of satellite antennas is highly dependent on spacecraft structure, antenna suite, &

mutual coupling effects. RF analyses and tests need to be carried out to validate the designs.

DL Talk: 2015

S. Rao

Reflector Antennas

Pg.11

Consists of two major assemblies

- reflector assembly

- feed assembly

Reflector assembly: provides required gain, determines coverage

shape, scan loss, beam squint etc. Comprises reflector, thermal

paint/cover, deployment boom mechanisms/gimbals, pointing error

- key design drivers: surface accuracy, loss, X-pol, thermal

stability

Feed assembly (horn + OMT + polarizer + filters/diplexers +TCs +W/G

Interfaces to repeater): provides proper illumination on the reflector,

dictates bandwidth, polarization, X-pol isolation, filtering etc.

- key design drivers: minimize loss, power handling,

tolerances, thermal, low PIM, wide bandwidths

Reflector & Feed Assembly performances are most crucial for satellite antennas

DL Talk: 2015

S. Rao Pg.12

Contoured Beam Antennas & Payloads

F F F

Transmit BFN

Receive Reject Filters

Offset Parabolic Reflector

OMT

DIPL DIPL

TxVP

TxHP

RxVP

RxHP

Shaped Reflector

OLD TECHNOLOGY

NEW TECHNOLOGY

Payload =

Antenna + Repeater

High dissipation

DL Talk: 2015

S. Rao

The beam shape fits closely to the coverage of a country or a region.

Used for FSS and BSS satellite services

Contoured or shaped beams are synthesized using two methods

Most common and cost-effective method is using shaped surface of

reflector to synthesize the beam (phase-only synthesis)

Key design aspects:

- maximize the minimum coverage area gain (MCAG)

- maximize the X-pol isolation within the coverage (C/X > 33 dB)

- minimize the copol levels outside the coverage and with interfering

beam (C/I > 30 dB)

Antenna types:

- parabolic reflector with feed array (old technology)

- dual-gridded reflector (limited to LP applications only)

- single shaped reflector (LP & CP)

- dual-reflector shaped Gregorian antenna (LP & CP)

- other types (SFOC, FFOC, Imaging, ADE etc.)

Pg.13

Contoured Beam Antennas

DL Talk: 2015

S. Rao

Synthesis Method for Shaped Reflector

Pg.14 DL Talk: 2015

2 3 4 5 6 7 8 9 10 11 12 13 14

X-axis,m

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

Y-a

xis

,m

Delta Surface (shaped-parabola) Contour Plot in m12.0m Antenna Single Feed Horn Design for GEO

Typical Delta-Surface

(S-Band)

Reflector

Diameter

(meters)

D/λ CONUS (13 sq. degrees)

Ku-Band

South America (26.45 sq.

degrees)

Ku-Band

EOC

Directivity

(dBi)

GAP EOC

Directivity

(dBi)

GAP

1.0 36.50 30.1 13303 27.9 16309

1.3 47.45 30.7 15274 28.4 18299

1.5 54.75 31.0 16366 28.7 19608

1.8 65.70 31.2 17137 28.9 20532

2.0 73.00 31.4 17945 29.1 21499

2.3 83.95 31.7 19228 29.25 22255

2.6 94.90 31.9 20135 29.4 23037

* S. Rao, “Design and Analysis of Multiple-Beam Reflector Antennas”, IEEE AP-Magazine, pp. 53-59, August 1999

Antenna Dir.,

Analysis

(dBi)

Dir., Computed

(dBi)

Case 1

(shaped)

27.66 27.60

Case 2

(shaped)

21.40 21.65

Case 3

(MBA)

46.68 46.54

Case 4

(MBA)

42.20 42.05

S. Rao

CONUS Beam for DBS

Pg.15

Highly Weighted Beam to compensate for Rain Fade

DL Talk: 2015

S. Rao

Contoured Beam Antennas: Multiple Coverage Regions

Pg.16

100” dia. SRA

100” dia. SRA

100” dia. SRA

100” dia. SRA

50” dia. GRA

100” dia. SRA

100” dia. SRA

100” dia. SRA

100” dia. SRA

50” dia. GRA

Single Beam Provides Weighted C-Band

Coverage to Africa and Turkey

-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4

Azimuth deg

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

9

E l e

v a t i o

n d

e g

Map View @ 42ºE

31.0dBW

32.0dBW

33.0dBW

34.0dBW

37.0dBW

38.0dBW

39.0dBW

40.0dBW

41.0dBW

C-Band EIRP Contour Plot Freq (MHz) = 3400 Polarization = LHCP CF (dBW) = +15.43

-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4

Azimuth deg

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

9

E l e

v a

t i o

n d

e g

Map View @ 42ºE

-11.0dB/K

-10.0dB/K

-9.0dB/K

-8.0dB/K

-7.0dB/K

-6.0dB/K

-5.0dB/K

-4.0dB/K

-3.0dB/K

C-Band G/T Contour Plot Freq (MHz) = 6725 Polarization = RHCP CF (dB/K) = -28.24

DL Talk: 2015

S. Rao

Gridded Reflectors & Gregorian Antennas

Pg.17

S1S2

CA,1XA,1CB,2

XB,1XA,2

XB,2

Koreasat F1Shaped Reflector

Assembly

DL Talk: 2015

S. Rao

Feed Assembly Design Considerations

Pg.18

Meet bandwidth requirements including thermal excursions

Provide desired illumination (> 15 dB taper) for the reflector or

beamwidth if used as the antenna

Meet the low X-pol requirements ( < -40 dB for FSS/BSS)

Low sidelobe levels (to minimize spill-over losses)

Power handling (6 dB margin by design, 3 dB by test)

PIM-free design features (< -135 dBm typical, thermal PIM)

Return loss > 25 dB

Low insertion loss (< 0.25 dB)

Meet desired isolation between bands (> 70 dB) & filter other bands

Low mass

Meet thermal requirements (-1400c to +1700c)

Better manufacturing tolerances

DL Talk: 2015

S. Rao

Horn Types for SATCOM

Pg.19

Corrugated Horns: wideband, supports dual-band, low X-pol, heavy

Potter Horns: Limited Bandwidth, smooth-wall, low mass

Multi-flare Horn: Multi-band capability (> octave BW), high efficiency,

low-mass, suitable for PCS 7 MBAs

Tri-furcated Horn: Suitable for LP, low spill-over loss, low X-pol

Bi-conical Horn: Suitable for TT&C

Waveguides, Quadri-filar helices (volutes) etc. (low gain)

Dielectric Horns: Not suitable for space (ESD issues)

Cup-Dipoles & PEC: Suitable for mobile satellites

Helical Antennas: Suitable at L-Band & UHF (GPS)

DL Talk: 2015

S. Rao

Feed Types

Pg.20

Trifurcated Horns

Ku-Corrugated Horn

Helix

Parameters Measured Performance

Frequency, GHz Tx: 3.625 - 4.2

Rx: 5.85 - 6.425

Axial Ratio < 0.2 dB on Axis

Insertion Loss Tx: < 0.15 dB

Rx: < 0.05 dB

Return Loss Tx: > 28 dB

Rx: > 32 dB

Isolation RHCP LHCP > 25 dB

Rx Tx > 60 dB

Peak Power 10 kW Multipaction

PIM < -140 dBm, 7th Order

Edge Taper 20 dB (±30°) Typical

Cross-Polar

Levels

< - 38 dB (±30°) relative to

peak

Size, Feed 28.5”(L) x 12”(W) x

12.7”(H)

Mass, Feed < 12 Kg (with brackets) Multi-Mode Horn

-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

Frequency (GHz)

(dB

)

Measured Cross Pol

Measured Co Pol

Simulated Co Pol

Simulated Cross Pol

Ku-Tracking Feed

Typical Test Plan

C-Band Tx/RX Feed Assembly

DL Talk: 2015

PEC

S. Rao

C-Band Feed Assemblies (Discrete vs Integrated)

Pg.21 DL Talk: 2015

PARAMETER

Discrete Integrated COMMENTS

Size 21” X 21” X 33” 12” X 12” X 12” INTG Feed is 8

times more

compact

Mass 18.3 lbs 12 lbs INTG Feed is 35%

lighter than

ANTEK’s

Tx Insertion Loss,

dB

0.16 0.13 INTG Feed has

lower insertion loss

due to compact size

and use of Cu

Rx Insertion Loss,

dB

0.09 0.06

Tx Axial ratio, dB

(Ambient/Thermal

with 5 deg. delta)

0.13 / 0.26 0.15 / 0.20 Thermal A.R of

INT feed is better

Rx Axial ratio, dB

(Ambient/Thermal)

0.13 / 0.20 0.16 / 0.19

Tx Return Loss, dB 30 30

Rx Return Loss, dB 31 30

Bench Tuning Extensive None Bench tuning is

required for

Disc feed

Qualification

Status

Flight Flight

Integrated feed assembly is more compact, better RF performance and low PIM risk

S. Rao

Multiple beam payload systems are extensively used for both military

and commercial satellites. Advantages are higher EIRP, G/T, spectral

re-use, & smaller ground terminals

- Direct Broadcast Satellites (12/17 GHz): EchoStar, DirecTV, HNS

- Ka Broadband Satellites (19/29 GHz): Anik-F2, ViaSat, EutelSat

- Military Satellites (20.5/30 GHz): Wideband Gapfiller Satellite (WGS)

Above systems operate in dual-bands and support single service

Future systems are required to support multiple satellite services

- Ku & Ka supporting DBS & broadband (12/18/20/30 GHz)

- TSAT and FABT (20/30/45 GHz) combining existing WGS & AEHF

Advanced antenna systems developed recently that simultaneously

supports three services (DBS, reverse DBS, and broadband) covering

FIVE DISCRETE BANDS over 12.3 GHz to 30.0 GHz (with BWR of 2.44)

Key components are:

- Multi-mode smooth wall horn supporting 5 discrete bands

- MBA design producing multiple beams at 5 bands simultaneously

Pg.22

Multiple Beam Antennas

Single satellite supporting multiple services is the future trend

DL Talk: 2015

S. Rao Pg.23

MBA versus Contoured Beam Payloads

• Beam diameter = 0.6°

• Beam Spacing = 0.52°

• EOC Gain ~ 46dBi

• Spectral Reuse Factor =15

(4 - cell)

• X - pol Isol ~ 25dB

• C - pol Isol ~ 12dB

- 3 - 2 - 1 0 1 2 3 4 5

Azimuth,deg

4

5

6

7

8

E l e

v a t i o n , d

e g

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30 31 32 33 34 35

36 37 38 39 40 41 42 43 44 45 46 47 48

49 50 51 52 53 54 55 56 57 58 59

60 61 62 63 64 65 66

67 68

68 beam layout on 105W map

- 3 - 2 - 1 0 1 2 3 4 5

Azimuth,deg

4

5

6

7

8

E l e

v a t i o n , d

e g

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30 31 32 33 34 35

36 37 38 39

- 3 - 2 - 1 0 1 2 3 4 5

Azimuth,deg

4

5

6

7

8

E l e

v a t i o n , d

e g

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30 31 32 33 34 35

36 37 38 39 40 41 42 43 44 45 46 47 48

49 50 51 52 53 54 55 56 57 58 59

60 61 62 63 64 65 66

67 68

68 beam layout on 105W map

- 5 - 4 - 3 - 2 - 1 0 1 2 3 4

5

6

7

8

- 5 - 4 - 3 - 2 - 1 0 1 2 3 4

5

6

7

8

• EOC Gain ~ 31dBi

• Spectral Reuse Factor =1

• X - pol Isol ~ 30dB

MBAs Allow Reuse of Spectrum Several Folds and Provide Increased Gain

DL Talk: 2015

S. Rao

Frequency Reuse Schemes for MBAs

Pg.24 DL Talk: 2015

A B A B

C D C D C

B A B A B

D C D C D

4-cell reuse

A B A BA B A B

C D C D CC D C D C

B A B A BB A B A B

D C D C DD C D C D

4-cell reuse

A B C A

B C A B C

A B C A B

B C A B C

3-cell reuse

A B C AA B C A

B C A B CB C A B C

A B C A BA B C A B

B C A B CB C A B C

3-cell reuseA B F G

C D E A B

F G C D E

E A B F G

7-cell reuse

A B F GA B F G

C D E A BC D E A B

F G C D EF G C D E

E A B F GE A B F G

7-cell reuse

Closest Spacing Between

Reuse Beams:

3-cell = 0.58 Adj. Beam Sp



Reuse Factor

(64 beams):

3-cell = 21.3

4-cell = 16

7-cell = 9.14

C/I = 9 dB, 12 dB, & 18 dB

for 3-C, 4-C, & 7-C

Hub B

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D

Hub EHub EHub EHub EHub E

Hub EHub EHub E

Hub FHub FHub F

Hub FHub FHub FHub F

Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H

Total : 46 beams

SE

NE

SW

NWB47

2 0 0 0

Hub H

Hub A

Hub C

Hub EHub G

Hub HHub F

Hub D

Hub B

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D


Hub EHub EHub E

Hub FHub FHub F


Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H

Total : 46 beams

SE

NE

SW

NWB47

2 0 0 0

Hub H

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D


Hub EHub EHub E

Hub FHub FHub F


Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H

Total : 46 beams

SE

NE

SW

NWB47

2 0 0 0

Hub H

Hub A

Hub C

Hub EHub G

Hub HHub F

Hub D

Hybrid-cell reuse

S. Rao

Frequency/Aperture Reuse Schemes

Pg.25

I II III I

II III I II III

III I II III I II

I II III I II III I

III I II III I II

II III I II III

I II III I

B C B C

D A D A D

B C B C B C

D A D A D A D

C B C B C B

D A D A D

C B C B

I

II

III

II III II III

IV I IV I IV

II III II III II III

IV I IV I IV I IV

III II III II III II

IV I IV I IV

III II III II

B C G A

G A D F E

D F E B C G

E B C G A D F

G A D F E B

F E B C G

C G A D

I

III IV

II

I I I I

I I I I I

I I I I I I

I I I I I I I

I I I I I I

I I I I I

I I I I

A B C A

B C A B C

C A B C A B

A B C A B C A

C A B C A B

B C A B C

A B C A

I

30

40

50

60

70

80

90

0.7 1 1.3 1.6 1.9 2.2 2.5 2.8 3.1

Horn Size in wavelength

Eff

icie

nc

y (

%)

1.0

30.0

15.5

Beam

Overl

ap

, d

B

SL

L, d

B

Efficiency Beam Overlap

Sidelobe

1.0

30.0

15.5

Beam

Overl

ap

, d

B

SL

L, d

B

1.0

30.0

15.5

Beam

Overl

ap

, d

B

SL

L, d

B

Efficiency Beam Overlap

Sidelobe

3-Cell Reuse with 1 Aperture 4-Cell Reuse with 3 Apertures

7-Cell Reuse with 4 Apertures

S. Rao et al., “Development of a 45 GHz multiple-beam antenna for military satellite communications”,

IEEE Trans. Antennas & Propagation, vol. 43, 00. 1036-1047, October 1995

DL Talk: 2015

S. Rao

Evolution of MBA Technology

Pg.26

Single -

Band

Antennas

(require 10

apertures)

Dual - band

Antennas

(high efficiency

of about 84%)

TX

TX RX

RX

TRCK

TX

TX

TRCK

CONFIG ‘ A ’ CONVENTIONAL MBA (10 APERTURES INCL. TRACKING)

RX

RX

Potter

Horns

TX/RX

TX/RX

TX/RX

TX/RX

DUAL - BAND MBA (4 APERTURES INCL.TRACKING) - REQUIRES DUAL - BAND HORNS

- SIGNIFICANT COST & MASS SAVING and 50% SAVINGS IN REAL - ESTATE REL. TO CONFIG ‘ A ’

DUAL - BAND MED. EFF. HORNS

CONFIG ‘ B ’

TX/RX

TX/RX

TX/RX

TX/RX

DUAL - BAND HIGH EFF. HORNS

CONFIG ‘ C ’

TX/RX

TX/RX

TX/RX

TX/RX

DUAL - BAND

HIGH EFF. HORNS

CONFIG ‘ D ’

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX/RX

TX/RX

TX/RX

TX/RX




CONFIG ‘ B ’

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX


CONFIG ‘ B ’

Dual - band Antennas

(medium efficiency

of about 54%)

Multi - band Antennas

(supports 5 bands

with efficiency of

74% to 82%)

Advanced MBA supporting 5 bands and 3 different services using

common antennas (Lockheed Martin ’ s patented technology)

Advanced MBA

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX/RX

TX/RX

TX/RX

TX/RX




CONFIG ‘ B ’

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX




CONFIG ‘ B ’

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

DUAL - BAND HIGH EFF. HORNS

CONFIG ‘ C ’

TX/RX

TX/RX

TX/RX

TX/RX

DUAL - BAND

HIGH EFF. HORNS

CONFIG ‘ D ’

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX

TX RX

RX

TRCK

TX

TX

TRCK


RX

RX

Potter

Horns

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX




CONFIG ‘ B ’

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX

TX/RX


CONFIG ‘ B ’

Dual - band Antennas

(low efficiency of

54%): Corr. Feed

Multi - band Antennas

(supports 5 bands

with efficiency of

74% to 82%)

Example: MBA supporting 5 bands and 3 different services using

Common antenna

Advanced MBA

DL Talk: 2015

S. Rao

Multiple Beam Layout

Pg.27

Hub B

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D


Hub EHub EHub E

Hub FHub FHub F


Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H

Hub A : 4 beamsHub B : 5 beamsHub C : 4 beamsHub D : 5 beamsHub E : 8 beamsHub F : 7 beamsHub G : 6 beams (incl AK)Hub H : 7 beams (incl HA)

Total : 46 beams

AMC-19 CONUS Beam/Channel/Hubs/Antenna Layout

105W

SE

NE

SW

NWB47

2 0 0 0

Hub H

Hub A

Hub C

Hub EHub G

Hub HHub F

Hub D

Hub B

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D


Hub EHub EHub E

Hub FHub FHub F


Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H


Total : 46 beams


105W

SE

NE

SW

NWB47

2 0 0 0

Hub H

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

B01B02B03B04B05B06B07B08

B09B10B11B12B13B14B15B16B17B18B19

B20B21B22B23B24B25B26B27B28B29

B30B31B32B33B34B35B36B37B38 B39

B40B41B42B43B44 B45

B46

B48

4 0 0 03 7 0 08 0 0 010 0 0 011 0 0 03 0 0 07 11 0 01 5 9 0

1 5 9 162 6 10 141 5 9 162 6 10 141 5 9 162 6 0 012 0 0 06 0 0 02 0 0 00 0 0 06 10 0 0

3 7 11 154 8 12 133 7 11 154 8 12 137 11 0 03 0 0 04 8 0 07 0 0 03 0 0 04 8 12 13

1 5 9 162 6 10 141 5 9 162 6 10 141 5 0 09 0 0 012 0 0 011 0 0 01 5 9 16 2 6 10 0

11 0 0 04 12 0 03 7 0 08 11 0 00 0 0 0 4 8 12 13

3 7 0 0

4 0 0 0

Hub AHub A

Hub AHub A

Hub B Hub B

Hub B Hub B

Hub B

Hub CHub C

Hub CHub C

Hub DHub D

Hub DHub DHub D


Hub EHub EHub E

Hub FHub FHub F


Hub GHub GHub G

Hub GHub G

Hub G

Hub H

Hub HHub HHub H

Hub HHub H


Total : 46 beams


105W

SE

NE

SW

NWB47

2 0 0 0

Hub H

Hub A

Hub C

Hub EHub G

Hub HHub F

Hub D

• Higher EIRP & G/T

• High Spectral Re-use (8 times freq X 2 times pol = 16)

• Satellite Capacity > 100 Gbps

46 spot beams

With 8 hubs

DL Talk: 2015

S. Rao

MBA for Local-Channel Broadcast

Pg.28

Multiple Beams with Non-Uniform Spacing & Non-Uniform Size

DL Talk: 2015

S. Rao

MBA Horn Comparison

Pg.29

Slope-Discon-

tinuityStep-Discon-

tinuity

CONVENTIONAL MULTI-MODE HORN MULTI-MODE HORN

HORN (CORRUG.) NARROW BAND WIDE BAND

DUAL-BAND SINGLE BAND DUAL-BAND

Thick Corrugations Step-Discontinuities Slope-Discontinuities

54 % Eff. Tx & Rx > 85 % over Tx or Rx > 85% over Tx & Rx

Heavy & Bulky Light & Compact Light & Compact

d < D D D

Slope-Discon-

tinuityStep-Discon-

tinuity

CONVENTIONAL MULTI-MODE HORN MULTI-MODE HORN

HORN (CORRUG.) NARROW BAND WIDE BAND

DUAL-BAND SINGLE BAND DUAL-BAND

Thick Corrugations Step-Discontinuities Slope-Discontinuities

54 % Eff. Tx & Rx > 85 % over Tx or Rx > 85% over Tx & Rx

Heavy & Bulky Light & Compact Light & Compact

d < D D D

DL Talk: 2015

S. Rao

Design Procedure for HEH

Pg.30

• Define horn aperture size, waveguide size, and the efficiency

• Select modal content (e.g., TE11, TE12, TE13/1.0, 0.31, 0.21)

• Determine radial dimension based on modes to set profile breakpoints

for the horn & use “slope-discontinuities”

• Optimize horn geometry to satisfy cost function:

• Aperture efficiency that can be achieved depends on the horn size.

– Larger the size, higher will be the aperture efficiency and lower

bandwidth

– Typical efficiency values for dual-band operation at K/Ka are in the

range 85% to 90%

– Trade is the higher efficiency at K, better match at K, and lower off-axis

x-pol at K/Ka

nfrq

i

iiadiixdiir dwtxpxpwtwtF1

222 )()()(

2) K. K. Chan ad S. Rao, “Design of high efficiency circular horn feeds for multi-beam reflector applications”,

K.2) IEEE Trans. Antennas & Propagation, Vol. 56, pp. 253-258, January 2008

1) S. Rao and M. Tang, “High-efficiency horns for an antenna system”, U.S. Patent # 7,463,207, December 09, 2008

DL Talk: 2015

S. Rao

HEH Performance Summary

Pg.31

- 6 0 .0 0 - 4 0 .0 0 - 2 0 .0 0 0 .0 0 2 0 . 0 0 4 0 . 0 0 6 0 . 0 0a n g le o f f - a x is ( d e g )

- 3 0 .0 0

- 2 0 .0 0

- 1 0 .0 0

0 .0 0

1 0 . 0 0

2 0 . 0 0

3 0 . 0 0

Rela

tive A

mp

litud

e

(dB

)

M e a s u r e d /P r e d ic t 4 5 d e g C o / X - p o l : 3 0 .0 0 G H z

M e a s u r e d 4 5 d e g C o - p o l / X - p o l

P r e d ic t 4 5 d e g C o - p o l / X - p o l

24.224.220.720.621.1

(86.6%)

21.05

(85.6%)

20.20

25.726.520.520.520.60

(84.5%)

20.60

(84.5%)

19.30

24.4

24.2

23.1

18.8

Measured

23.0

26.0

24.1

19.8

Predict

Cross-Pol (dB)

36.3

33.0

30.8

30.6

Predict

Return Loss (dB)

27.624.5

(85.9%)

24.46

(85.1%)

30.00

34.724.2

(84.6%)

24.23

(85.2%)

29.20

29.023.8

(82.1%)

23.89

(83.9%)

28.30

30.820.10

(83.8%)

20.08

(83.4%)

18.30

MeasuredMeasuredPredict

Directivity (dBi)/

Efficiency

Frequency

(GHz)

24.224.220.720.621.1

(86.6%)

21.05

(85.6%)

20.20

25.726.520.520.520.60

(84.5%)

20.60

(84.5%)

19.30

24.4

24.2

23.1

18.8

Measured

23.0

26.0

24.1

19.8

Predict

Cross-Pol (dB)

36.3

33.0

30.8

30.6

Predict

Return Loss (dB)

27.624.5

(85.9%)

24.46

(85.1%)

30.00

34.724.2

(84.6%)

24.23

(85.2%)

29.20

29.023.8

(82.1%)

23.89

(83.9%)

28.30

30.820.10

(83.8%)

20.08

(83.4%)

18.30

MeasuredMeasuredPredict

Directivity (dBi)/

Efficiency

Frequency

(GHz)

Apertu re E ffic iency P lo t

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

18.0 20.0 22.0 24.0 26.0 28.0 30.0

Fre que ncy,G H z

pe

rc

en

tag

e e

ff(%

)

potter ideal corrugated des ignD des ignF des ignH

edge taper

-25.00

-20.00

-15.00

-10.00

-5.00

18.0 20.0 22.0 24.0 26.0 28.0 30.0

fre que ncy(G H z)

ed

ge

ta

pe

r(d

B)

potter ideal corrugated des ignD des ignF des ignH

DL Talk: 2015

S. Rao

Quad-Band Horn with Smooth Walls

(2.1" diameter)

-1.5

-1

-0.5

0

0.5

1

1.5

0 2 4 6 8

Length (inches)

Dia

mete

r (i

nch

es)

Pg.32

Multi-band Horn Geometry & Performance

1

2

3

4

5

6

7

7.9”

2.1”

D L

(in.) (in.)

1 0.640 0.000

2 0.640 0.200

3 0.646 0.506

4 0.877 1.175

5 1.299 2.718

6 1.560 5.918

7 2.100 7.901

Frequency Return Loss X-pol (20º) Efficiency

(GHz) (dB) (dB) (%)

12.5 -26.5 -22.3 82

17.3 -48.0 -22.5 80

17.8 -50.2 -23.6 80

18.4 -43.6 -23.6 79

20.2 -41.7 -22.1 76

24.8 -50.1 -23.0 76

25.3 -44.3 -23.7 76

28.5 -44.0 -23.9 75

30.0 -45.2 -22.1 74

Key Performance Results

• Return Loss: > 26 dB

• Efficiency: 74% to 82%

• X-pol: < -22 dB

2.2 λ to

5.3 λ

DL Talk: 2015

S. Rao Pg.33

Feed Pattern (Defocus=0” & 1”)

Feed defocus of 1.0” improved higher band performance

-20

0

20

40

60

80

100

120

140

160

180

0 5 10 15 20 25 30

Dir

ec

tiv

ity

(d

Bi)

Angle (deg)

Quad-band Horn Phase(no defocus)

12.45 GHZ

17.55 GHz

19.30 GHz

25.0 GHz

29.25 GHz

-40

-20

0

20

40

60

80

100

120

140

160

0 5 10 15 20 25 30

Dir

ec

tiv

ity

(d

Bi)

Angle (deg)

Quad-band Horn Phase(defocus = 1")

12.45 GHZ

17.55 GHz

19.30 GHz

25.0 GHz

29.25 GHz

DL Talk: 2015

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Dir

ec

tiv

ity

(d

Bi)

Angle (deg)

Quad-band Forward DBS Horn Pattern

12.45 GHz co-pol

12.45 GHZ x-pol

17.55 GHz co-pol

17.55 GHz x-pol

19.30 GHz co-pol

19.30 GHz x-pol

29.25 GHz co-pol

29.25 GHz x-pol

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Dir

ec

tiv

ity

(d

Bi)

Angle (deg)

Quad-band Reverse DBS Horn Pattern

17.55 GHz co-pol

17.55 GHz x-pol

19.30 GHz co-pol

19.30 GHz x-pol

25.0 GHz co-pol

25.0 GHz x-pol

29.25 GHz co-pol

29.25 GHz x-pol

S. Rao Pg.34

Secondary Pattern (Defocus=1.0”)

EOC Directivity

Freq Coverage Peak Co-pol C/X

12.45 ±0.5º 49.0 47.4 32.8

17.55 ±0.5º 51.9 49.5 28.7

19.30 ±0.5º 52.6 49.8 27.4

25.00 ±0.5º 53.5 50.1 23.3

29.25 ±0.5º 53.6 50.0 18.4

10

15

20

25

30

35

40

45

50

55

-4 -3 -2 -1 0 1 2 3 4

Dir

ec

tiv

ity (

dB

i)

Scan Angle (deg)

Secondary Patern for Forward Quad-band horn(defocus=1.0")

12.45 GHz co-pol

12.45 GHz x-pol

17.55 GHz co-pol

17.55 GHz x-pol

19.3 GHz co-pol

19.3 GHz x-pol

29.25 GHz co-pol

29.25 GHz x-pol10

15

20

25

30

35

40

45

50

55

-4 -3 -2 -1 0 1 2 3 4

Dir

ecti

vit

y (

dB

i)

Scan Angle (deg)

Secondary Patern for Reverse Quad-band horn(defocus=1.0")

17.55 GHz co-pol

17.55 GHz x-pol

19.3 GHz co-pol

19.3 GHz x-pol

25.0 GHz co-pol

25.0 GHz x-pol

29.25 GHz co-pol

29.25 GHz x-pol

48.0

49.0

50.0

51.0

52.0

53.0

54.0

0 1 2 3

Dir

ecti

vit

y (

dB

i)

Defocus (inches)

Peak Directivity of various Horn Defocus

12.45 GHz

17.55 GHz

19.3 GHz

25.0 GHz

29.25 GHz

DL Talk: 2015

S. Rao Pg.35

Multi-Band Feed Assembly Schematic

W/G Bend &

Combiner

Multi-Band

High Efficiency

Horn

Filter to reject

17/20/25/30 GHz

(Qty. 4)

12 GHz

LCP

12 GHz

RCP

Symmetrical

OMT & Polarizer

12 GHz

W/G Bend &

Combiner

Filter to reject

25/30 GHz (Qty. 4)

25/30 GHz

Polarizer

Diplexer

Diplexer

20 GHz RCP

17 GHz RCP

17 GHz LCP

20 GHz LCP

Symmetrical OMT,

Polarizer & Diplexer

at 17/20 GHz

25 GHz RCP

25 GHz LCP

Size: 2.27” X 15.0 in

Mass: 1 lb

Efficiency: > 85%

K/Ka

K/Ka band Intg. Feed

18 GHz – 30 GHz

RL > 25 dB

IL < 0.25 dB

A.R < 0.25 dB

Tx/RX Isol. > 80 dB

Diplexer

Diplexer 30 GHz LCP

30 GHz RCP

The feed network need to fit within the real-estate dictated by the horn aperture

DL Talk: 2015

S. Rao Pg.36

Typical Multiple Beam Layout over CONUS

Coverage (119° W orbital location)

Aper #1

Aper #2

Aper #3

Aper #4

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

1

2

3

4

5

6

7

8

9

11

10

13

12

15

14

16

17

18

19

20

21

22

24

23

25

26

28

27 29

30

31

33

3432

35

36

37

39

38

40

DMA Ranking (2006 Nielsen Ranking)

119W

26 Beams cover 40 top DMAs

(6 to 7 beams per aperture)

DL Talk: 2015

S. Rao

Stepped Reflector Antenna for Multi-Band

Applications

Pg.37

0

30

60

90

120

150

0 40 80 120 160 200

Central portion of

the reflector

(shaped or parabola)

Stepped ring n

(n=1 to N)


Step Size h ?m*[ 180 ± (feed phase( Θ i ) - feed phase( Θ 0 ))] * (π/180) * (λ /2 π) * (1/2)

Step Size h 1

Step Size h n REFLECTOR

0

30

60

90

120

150

0 40 80 120 160 200

Central portion of

the reflector


Stepped ring n

(n=1 to N)


Step Size h =m*[ 180 ± (feed phase( Θ i ) - feed phase( Θ 0 ))] * (π/180) * (λ /2 π) * (1/2)

Step Size h 1

Step Size h n REFLECTOR

DL Talk: 2015

S. Rao

SRA with Frequency-Dependant Horn Design

Pg.38

• DBHEH Design can exploit phase center variation between

bands to minimize SRA step height

• Phase patterns of horns for dual-band & multi-band horns

are critical to optimize antenna performance

dTx

P.C.

Rx

P.C.

ΔPhase = kd(1-cosθ0 )

Δ Phase = 840 ( θ0 = 250, d=1”, Freq=30 GHz)

DL Talk: 2015

S. Rao

Impact of SRA on Receive Beam Patterns

Pg.39

Secondary Pattern Cut @ 29200MHz

43

44

45

46

47

48

49

50

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

Theta, deg

Patt

ern

, dB

i

80" reflector 80" plus 5" ring 80" plus 10" ring coverage coverage plus PE

1.48dB0.85dB

0.96dB

0.55dB

Step Depth=0.10”Secondary Pattern Cut @ 29200MHz

43

44

45

46

47

48

49

50

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

Theta, deg

Patt

ern

, dB

i


1.48dB0.85dB

0.96dB

0.55dB

Secondary Pattern Cut @ 29200MHz

43

44

45

46

47

48

49

50

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

Theta, deg

Patt

ern

, dB

i


1.48dB0.85dB

0.96dB

0.55dB

Step Depth=0.10”

DL Talk: 2015

S. Rao

Large Deployable Reflectors for MSS

Pg.40

(a) (b) (c)

(d) (e) (f)

AstroMesh

12 meter Antenna

(Perimeter Truss)

Harris 22 meter Antenna (Hoop Truss)

Mesh Reflectivity Loss [13]

Knitted gold - moli mesh closeup [8]

DL Talk: 2015

S. Rao

Reconfigurable Antenna Block Diagram

Pg.41

TC

OHM

(N=40 to 64)

IHM

M:1

1:N

M:1 M:1

1:N 1:N

B1 B2 BM

1 2 3 N

Test Couplers (N)

BPFs (N)

8x8 OHMs (Qty. 5 to 8)

Redundancy Output Switch Matrix (N)

SSPAs with Redundancy (50 to 80)

Redundancy Input Switch Matrix (N)

8x8 IHMs (Qty. 5 to 8)

Combining Networks (N)

Dividing Networks (M)

Beam Ports (M=8 to 10)

1 2 N

Mesh Reflector (~ 15 m diameter)

(SRI, DRI or NFR)

TC TC TC

VPs (Qty. 320 to 640) VAs (Qty. 320 to 640)

DL Talk: 2015

S. Rao

Non-Focused Reflector (NFR) Concept

Pg.42

• Non-Focused Reflector (NFR) with symmetrical shaping

• By opening-up or closing-in the paraboloid gradually, a quadratic

phase-front is created in the aperture plane (instead of uniform

phase-front)

• The quadratic phase-front broadens the element beams significantly (1.5 to 3 times)

• Main advantage is fewer number of feed elements (by a factor of 3 or more)

• Scan performance improves (a) due to symmetrical shaping, and (b) due to feed array & reflector geometrical relation is more optimal

• Element beams are combined in the far-field with non-uniform amplitude and non-uniform phase excitations to synthesize the

antenna beam contour

• MPA allows uniform loading of the amplifiers

S. Rao et al., “Reconfigurable Payload Using Non-Focused Reflector Antenna for HEO

and LEO Satellites”, U.S. Patent # 7710340, May 04, 2010

DL Talk: 2015

S. Rao

NFR Concept

Pg.43

Mesh Reflector

Uniform phase-front

(paraboloid)

Quadratic phase-front

(closing-in surface)

Far Field

Element Beam

Parabola

Non-Parabola

Quadratic phase-front

(opening-up surface)

DL Talk: 2015

S. Rao

NFR For Flexible CONUS Coverage (DABS)

Pg.44

(non-parabolic)12m Mesh Non-Focused Reflector

-

1:M

M:1

1:M

M:1

1:M

M:1

1:M

M:1

1:N

COMBINING

NETWORK

TWTAs

DIVIDING

NETWORK

VPS

DIVIDING

NETWORK

COMBINING

NETWORK

DIVIDING

NETWORK

DIVIDING

NETWORK

1 -------- N

-5 -4 -3 -2 -1 0 1 2 32

3

4

5

6

7

8

9

10

map view from GEO @ 90ºWDirectivity Contour Plot.37 Element Beams12m antenna.

-5 -4 -3 -2 -1 0 1 2 32

3

4

5

6

7

8

9

10

map view from GEO @ 90ºWDirectivity Contour Plot.37 element defocus fed 12m antenna.Complex excitation optimization.

Element Beams

Synthesized

CONUS Beam for

Yaw = 0 & 90 deg.

DL Talk: 2015

S. Rao

MBA for High Capacity Satellites

Pg.45

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW

Wild Blue : EIRP Contour (56 Beams, 14 Gateways) (beam spacing = 0.35º)

NE NW

SE SW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

Contour levels :

45,48,64,66,68 dBW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

-6 -5 -4 -3 -2 -1 0 1 24

5

6

7

8

1 3 5

15 17 19 21

31 33 35

43 45 47

51

2 4

16 18 20 22

30 32 34 36

44 46

49

53

6 8 10 12 14

24 26 28

38 40 42

50

54

56

7 9 11 13

23 25 27 29

37 39 41

48

52

55

u1 u1 u1

u1 u1 u1 u1

u1 u1 u1

u1 u1 u1

u1

u3

u4

u2 u2

u2 u2 u2 u2

u2 u2 u2 u2

u2 u2

u2

u2

u3 u3 u3 u3 u3

u3 u3 u3

u3 u3 u3

u3

u3

u4 u4 u4 u4

u4 u4 u4 u4

u4 u4 u4

u4

u4

1

2

34

5

6

7

8

9

10

11

12

13

14

Rapid

Santa

ElPasoTucson

Milford

WichitaFalls

Logan

Calgary

Cheyenne

winnipeg

Bismarck

Bozeman

Hays

Saskatoon

77ºW


NE NW

SE SW

Contour levels :

45,48,64,66,68 dBW

Contour Level : 65 dBW for User Beams

59 dBW for GW Beams

DL Talk: 2015

Tx Azimuth Cut of Beam 24

35

40

45

50

55

60

65

70

75

-2.50 -2.00 -1.50 -1.00

Angle (deg)

EIR

P (

dB

W)

Co-pol

Beam

Reuse

24 dB

Tx Azimuth Cut of Beam 24

35

40

45

50

55

60

65

70

75

-2.50 -2.00 -1.50 -1.00

Angle (deg)

EIR

P (

dB

W)

Co-pol

Beam

Reuse

24 dB

Rx Azimuth Cut of Beam 24

-10

-5

0

5

10

15

20

25

30

-2.50 -2.00 -1.50 -1.00

Angle (deg)

G/T

(d

B/K

)

Co-pol

Beam

Reuse

26 dB

Rx Azimuth Cut of Beam 24

-10

-5

0

5

10

15

20

25

30

-2.50 -2.00 -1.50 -1.00

Angle (deg)

G/T

(d

B/K

)

Co-pol

Beam

Reuse

26 dB

EIRP > 65 dBW

C/I > 24 dB (single interferer)

G/T > 20 dB/K

C/I > 26 dB (single interferer)

S. Rao

Common Aperture Antenna for Shaped and Spot Beams

Pg.46

WestEast

North

South

Ku-Band

North America & Europe

Tx/Rx

Ka-Band South America

100” Reflector

Ku-Band Brazil Tx/Rx

100” Reflector

C-Band Tx/Rx

100” Reflector

Ku-Band South America

Tx/Rx

100” Reflector

BR feed

-4 5 .0 0

1 5. 00

-3 0 .0 0-9 0 .0 0

1 /O c t/ 19 9 8 La tit ud -Lo ng it ud Po s i .S a t : 3 0 .0 0 O

BC

BA

BB

SC1

SC2

SA2

SA1

SB

SB

SD

NA

NANC

NB

1 5. 0 0

6 5. 0 0

3 8. 0 0-3 2 .0 0

1 /O c t /1 99 8 La tit ud -Lo n gi tu d P o s i .S a t : 30 .0 0 O

IA

EA

IB’

IC’

IA’

EA

Bogota

BuenosAires

Caracas

Lima_GW02

MexicoCity

Recife

Rio_GW01SaoPaulo

Santiago_GW02

Brasila

Madrid_GW02

-9 -6 -3 0 3 6 9

Azimuth, deg

-9

-6

-3

0

3

6

9

Ele

va

tio

n,

de

g

Orbital Slot: -61º (West) Hispasat-S2Ka-Band DownlinkFreq(GHz):19.950CF(dBW)=+15.07

58dBW

59dBW

60dBW

61dBW

62dBW

55dBW

56dBW

57dBW

58dBW

59dBW

All others RIO/SaoPaulo

Common Aperture Antenna

(3 apertures combined

into one)

Ku-bandNorth Americacoverage

Ka-band city coverage

10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)

Ka-band beam pattern

10

15

20

25

30

35

40

45

50

2 3 4 5 6 7 8

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)


10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (d

Bi)

Azimuth (deg)


Ku-bandEuropecoverage

B#1

B#2

B#3

B#4



10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)


10

15

20

25

30

35

40

45

50

2 3 4 5 6 7 8

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)


10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (d

Bi)

Azimuth (deg)





10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)


10

15

20

25

30

35

40

45

50

2 3 4 5 6 7 8

Dir

ect

ivit

y (

dB

i)

Azimuth (deg)


10

15

20

25

30

35

40

45

50

-3 -2 -1 0 1 2 3

Dir

ect

ivit

y (d

Bi)

Azimuth (deg)



B#1

B#2

B#3

B#4

10

15

20

25

30

35

40

45

50

-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Dir

ect

ivit

y (d

Bi)

Azimuth (deg)

Antenna Pattern

defocus 0"

defocus -20"

defocus -40"

defocus -60"

defocus -80"

10

15

20

25

30

35

40

45

50

-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Dir

ect

ivit

y (d

Bi)

Azimuth (deg)

Antenna Pattern

defocus 0"

defocus -20"

defocus -40"

defocus -60"

defocus -80"

WestEast

North

South

Ku-Band

North America Tx/Rx

100” Reflector


100” Reflector

C-Band Tx/Rx

100” Reflector

Ku-Band South

America Tx/Rx

100” Reflector

Ku-Band Europe

Tx/Rx

85” Gregorian

-4 5 .0 0

1 5. 00

-3 0 .0 0-9 0 .0 0


BC

BA

BB

SC1

SC2

SA2

SA1

SB

SB

SD

Bogota

BuenosAires

Caracas

Lima_GW02

MexicoCity

Recife

Rio_GW01SaoPaulo

Santiago_GW02

Brasila

Madrid_GW02

-9 -6 -3 0 3 6 9

Azimuth, deg

-9

-6

-3

0

3

6

9

Ele

va

tio

n,

de

g


58dBW

59dBW

60dBW

61dBW

62dBW

55dBW

56dBW

57dBW

58dBW

59dBW


1 5. 0 0

6 5. 0 0

3 8. 0 0-3 2 .0 0


IA

EA

IB’

IC’

IA’

EA

NA

NANC

NB

Ka-Band

Tx/Rx

45” Gregorian

Combined into one

WestEast

North

South

Ku-Band

North America Tx/Rx

100” Reflector


100” Reflector

C-Band Tx/Rx

100” Reflector

Ku-Band South

America Tx/Rx

100” Reflector

Ku-Band Europe

Tx/Rx

85” Gregorian

-4 5 .0 0

1 5. 00

-3 0 .0 0-9 0 .0 0


BC

BA

BB

SC1

SC2

SA2

SA1

SB

SB

SD

Bogota

BuenosAires

Caracas

Lima_GW02

MexicoCity

Recife

Rio_GW01SaoPaulo

Santiago_GW02

Brasila

Madrid_GW02

-9 -6 -3 0 3 6 9

Azimuth, deg

-9

-6

-3

0

3

6

9

Ele

va

tio

n,

de

g


58dBW

59dBW

60dBW

61dBW

62dBW

55dBW

56dBW

57dBW

58dBW

59dBW


1 5. 0 0

6 5. 0 0

3 8. 0 0-3 2 .0 0


IA

EA

IB’

IC’

IA’

EA

NA

NANC

NB

Ka-Band

Tx/Rx

45” Gregorian

Combined into one

WestEast

North

South

Ku-Band

North America Tx/Rx

100” Reflector


100” Reflector

C-Band Tx/Rx

100” Reflector

Ku-Band South

America Tx/Rx

100” Reflector

Ku-Band Europe

Tx/Rx

85” Gregorian

-4 5 .0 0

1 5. 00

-3 0 .0 0-9 0 .0 0


BC

BA

BB

SC1

SC2

SA2

SA1

SB

SB

SD

Bogota

BuenosAires

Caracas

Lima_GW02

MexicoCity

Recife

Rio_GW01SaoPaulo

Santiago_GW02

Brasila

Madrid_GW02

-9 -6 -3 0 3 6 9

Azimuth, deg

-9

-6

-3

0

3

6

9

Ele

va

tio

n,

de

g


58dBW

59dBW

60dBW

61dBW

62dBW

55dBW

56dBW

57dBW

58dBW

59dBW


1 5. 0 0

6 5. 0 0

3 8. 0 0-3 2 .0 0


IA

EA

IB’

IC’

IA’

EA

NA

NANC

NB

Ka-Band

Tx/Rx

45” Gregorian

Combined into one

Diameter

=100”

Ka-band feeds

Ku-band feed

Spherical cap

To ka feeds

Adjust defocus to for flat phase

θ

d

r1

r1’

r0

F

F’

Reflector

shaped for

Ku-band

contoured

beams

Diameter

=100”

Ka-band feeds

Ku-band feed

Spherical cap

To ka feeds

Adjust defocus to for flat phase

θ

d

r1

r1’

r0

F

F’

Reflector

shaped for

Ku-band

contoured

beams

DL Talk: 2015

S. Rao

Advanced Reflectors: X-Link & Gateway Applications

Pg.47 DL Talk: 2015

S. Rao

Phased Arrays with Flexible Beams

Pg.48

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

-10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0

WBR OPA Rx Patterns; Peak = 43.86 dBi

kx

ky

-0.5 0 0.5-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-20

-10

0

10

20

30

40

50

-40 -30 -20 -10 0 10 20 30 40-20

-10

0

10

20

30

40

50

directivity (

dB

)

DL Talk: 2015

S. Rao

Array Design

Scan Angle (degrees)

Element Spacing in λ at Highest Freq. *

Number of Elements for 1000 λ**2 at Highest Freq

Square Lattice Hexagonal Lattice

Square Lattice Hexagonal Lattice

80 0.50 0.58 4000 3464

70 0.52 0.60 3698 3208

60 0.55 0.64 3306 2863

50 0.61 0.70 2687 2327

40 0.71 0.82 1984 1718

30 0.88 1.02 1291 1118

20 1.19 1.37 706 611 * Assumes closest grating lobe location as 10 deg. larger than the maximum scan angle

• Number of Elements:

• is the element gain at bore-sight

• Array Directivity:

)(1.010 eA DD

N

eD

Peak Gain

(over cov.)

Insertion Loss ScanLoss

(elem.Patt

roll-off)

mLSpA ITSLLGD

Taper Loss

(about 90%)

Impl. Margin

DL Talk: 2015 Pg.49

S. Rao

Wideband Arrays (> 3:1 BWR)

Pg.50

Stacked-Patch Array

DL Talk: 2015

S. Rao

Dual-Band Feed Assembly Integrated with

IFAs & OFAs, & TCs

Pg.51

Integrated Harmonic

Reject Filters with

Existing Low Pass

Filters (4x)

Integrated Receive

Band Pass Filters (2x)

Transmit Band Pass

Filters (2x)

Transmit Bidirectional

Test Couplers (2x)

Receive Bidirectional

Test Couplers (2x)

IFAs, OFAs, and TCs are integrated with the feed assembly.

Four bi-directional TCs are required (2 Tx and 2 Rx)

High-level integration of the feeds provides about 21 Kgs mass savings,

$ 6 million cost saving, and 0.40 dB improved RF performance DL Talk: 2015

S. Rao

Antennas for Scientific Missions (cont’d)

DL Talk # 1 Pg.52

MRO’s antenna after integration. Spring-back Reflector

Galileo Reflector

SMAP Reflector

Voyager Mission

S. Rao

High Power TVAC Test Method Using Pick-Up Horn (PUH) Loads

Pg.53

Freq Synth

Freq Synth

1

K

O

S

M

TWTA 1

TWTA 16

Horn 1

Horn 4

PUH 1

PUH 4

Horn 5 PUH 5

German Spot

1600 w Avg

500 w Avg

HP Load

HP Load

TWTAs

1-4

K

O

S

M

TWTA 1

TWTA 16

O- Mux

PUH Monitor & Ctl

PUH Cooling Ctl

and LN2 Regulator Regulates LN2 Temp to -100C

GPIB

TCs for Temp Monitoring

Cooled by

Florinert Unit

Will Shut off rf input if temp/pwr

exceeds threshold automatically

Audible

Alarm

1 52 TCs IF

A &

RC

VR

Ground

Equipment

X

X

X

X

X

OMUX X 2

OMUX X 2

FWD & RTN

PWR Monitoring

Flt Cplr

Rf Power

Monitor

DL Talk: 2015

S. Rao

PUH Load

Pg.54 DL Talk: 2015

1 & 4 :

Medium

Power Slot

2 & 3 :

High

Power Slot

5 : RF Choke 6 : RF Transparent

Protective Cover

(Kapton)

10 : Coolant Inlet

9 : SS 304 Side Covers

11 : Coolant Outlet

13 : Cover

Screw

SS6-32

14 : RF

Shorting

Back Plate

19 : Vacuum Seal

(Using Knife Edge

And Sn96 Solder)

8 : Copper

C101 Housing 12 : Venting

Holes

7 : Copper

Clamp Ring

(for Kapton

Cover)

S. Rao et al., “A novel method for high-power thermal vacuum testing of satellite payloads using

pick-up horns”, IEEE Antennas & Propagation Magazine, Vol. 49, #3, pp. 134-145, June 2007

S. Rao et al., U.S. Patent #s 7598919 & 7692593, 2010

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

10.7 10.95 11.2 11.45 11.7 11.95 12.2 12.45 12.7

Frequency (GHz)

dB

Return Loss IA

Return Loss HOT

Return Loss Cold

Return Loss FA

Spec. Line

S. Rao

Passive Inter-modulation (PIM)

Pg.55

SATELLITE PIM

SELF INTERFERENCE

RX TX

PIM

SOURCE

NORMAL TX + TRANSLATED PIM

PIM

SATELLITE

NORMAL RX

50 to 85 dB

TX- RX

ISOLATION

SATELLITE PIM

SELF INTERFERENCE

RX TX

PIM

SOURCE

NORMAL TX + TRANSLATED PIM

PIM

SATELLITE

NORMAL RX

50 to 85 dB

TX- RX

ISOLATION

TX –RX DIPLEXER

HIGH PWR LOAD

TX REJECT

FILTER

F1

F2

RX REJECT

FILTER

TX - RX

DIPLEXER

PRW

DUT

LNA

SPECTRUM

ANALYZER

OR

RECEIVER

REF LO

THERMAL

CHAMBER

PRW

MUX

LOAD

TX REJECT

FILTER

F1

F2

RX REJECT

FILTER PRW

LNA

SPECTRUM

ANALYZER

OR

RECEIVER

REF LO

ANECHOIC & THERMAL

CHAMBER

PRW RX REJECT

FILTER

SPACE COMBINED

DUT

DL Talk: 2015

10 15 20 25 30-200

-180

-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

140

160

CW

Level (w

att

s)

and T

em

p (

°C)

10 15 20 25 30-165

-160

-155

-150

-145

-140

-135

-130

-125

-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

time (hours)

PIM

Level (d

Bm

)

Test Start: 31/Mar/2010, 07:06:00

S. Rao

Multipaction

Pg.56

E E

- -

E

-

Electrons striking the opposite surface at high velocity form a sheet of secondary electrons

Striking the opposite δ=2 surfa ce at high velocity produces 2 secondary electrons accelerating in the opposite direction

A stray electron from t he environment enters and is accelerated by the RF electric field

- - - -

fd = 1 GHz*0.06 inches

≈ 65 volts

≈ 510 volts

Fundamental Mode 1/2 cycle

Odd multiples of one half cycle

3/2 cycle


≈ 65 volts

≈ 510 volts



3/2 cycle


≈ 65 volts

≈ 510 volts



3/2 cycle

20 Crossing

period 10 ns

Average voltage

25 volts RMS

1 108

5 109

0 5 109

1 108

0

20

40

60

80

INSTANTANEOUS RMS VOLTAGE

Time (seconds)

Voltag

e (v

olts

rms)

Eavg

2 109

2 109

20 Crossing

period 10 ns

Average voltage

25 volts RMS

Average voltage

25 volts RMS

1 108

5 109

0 5 109

1 108

0

20

40

60

80

INSTANTANEOUS RMS VOLTAGE

Time (seconds)

Voltag

e (v

olts

rms)

Eavg

2 109

2 109

DL Talk: 2015

S. Rao

TT&C Antennas

Pg.57

TT&C RF

Equipment

Command receivers

Telemetry transmitters

Command Horn Antenna(s)

Telemetry Horn Antenna(s)

Command and Telemetry

Omni Antenna

Miscellaneous RF Hardware

Antenna: Omni WC Horn Indicates requirement angles.

Angle w.r.t. Z Axis Gain (dB) Gain (dB) Omni-WC Horn WC Horn-Omni

-180 -35.0 -18.0

-170 -24.0 -23.0

-160 -16.0 -30.0

-150 -10.5 -30.0

-140 -6.0 -30.0

-130 -2.2 -30.0

-120 0.2 -30.0

-110 1.8 -28.0 29.8 0

-100 2.4 -24.2 26.6 0

-90 2.5 -22.0 24.5 0

-80 2.2 -20.0 22.2 0

-70 1.5 -23.3 24.8 0

-60 0.0 -15.0

-50 -4.5 -3.0

-40 -9.0 5.5

-30 -12.0 8.0 20.0 0

-20 -11.3 9.7 21.0 0

-10 -20.0 11.5 31.5 0

0 -37.5 12.5 50.0 0

10 -20.0 11.5 31.5 0

20 -10.8 9.5 20.3 0

30 -10.0 8.1 18.1 0

40 -7.0 4.5

50 -3.0 -3.5

60 0.1 -15.0

70 1.8 -22.5 24.3 0

80 2.3 -20.2 22.5 0

90 2.5 -22.0 24.5 0

100 2.3 -24.3 26.6 0

110 1.5 -28.0 29.5 0

120 0.0 -30.0

130 -2.0 -30.0

140 -5.0 -30.0

150 -10.5 -30.0

160 -15.5 -30.0

170 -23.0 -23.0

180 -34.0 -18.0

Gain Difference

-35

-30

-25

-20

-15

-10

-5

0

5

10

15

-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180

Ga

in (

dB

i)

Angle from Z Axis (°)

TT&C RF Antenna Gains @ TX and RX Frequencies

Omni WA Horn Requirement

Omni

Wide Angle Horn

Earth Deck Panel (S-1)

-2A)

Omni

Wide Angle Horn

Earth Deck Panel

TCRX2TCRX1 TTX2

H

Low

Power

TTX1

Low

Power

H

High

Power

High

Power

H

RX WCA

(LHCP)

RX OMNI

(LHCP)

TX WCA

(RHCP)

TX OMNI

(RHCP)

COMM

ANTENNA

DL Talk: 2015

S. Rao

High Bay

Planar near-field range: High gain and medium gain antennas

- measure near-fields over +/- 800

Spherical near-field range: Typically used for medium gain and low-

gain antennas

- precise probe to AUT alignment and probe compensation

required (not used often)

Far-field range: Out-door range with real-time measurements

- suffers from ground reflections and weather conditions

Compact range: the best range allowing real-time measurements of

high gain/medium gain antenna patterns

- employs SFOC dual-reflector system to create plane-wave

quiet-zone region for AUT placement and measurements

Anechoic chamber: indoor far-field measurements for medium and

low gain antennas

- global horns, omni-antennas

Test Equipment: PIM test equipment, high power test set-up, thermal

chamber, TVAC chamber, network analyzer etc.

Pg.58

Test Ranges & Equipment

DL Talk: 2015

S. Rao

Future trends in satellite antennas and payloads include:

- high capacity satellites for PCS with > 500 Gbps capacity

- used of large deployable mesh-reflectors with apertures > 20 meters

- multiple band hybrid payloads, light-weight compact feed assemblies

- larger power TWTAs, larger power spacecrafts (> 20 KW DC)

- reconfigurable antennas with flexible beam shape and beam location,

origami based antenna structures

- agile payloads with anti-jamming capability

- low-cost payloads, meta-materials, EBG, nano-technology etc.

- ultra wideband antennas with > 20:1 bandwidth ratio

- high power handling and low PIM feed technologies

Antenna plays a critical role in future payloads for satellites.

Conceptual development matching the customer needs

Antenna engineer needs several skills to develop advanced hardware needed

for complex antenna systems of the 21st century

Pg.59

Conclusions

21st Century satellites need innovative antenna solutions

leading to advanced payloads

DL Talk: 2015

advanced antenna systems for 21 century satellite ... · hybrid antennas ... - lens antennas *...

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