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
4-cell = 0.85 Adj. Beam Sp
7-cell = 1.49 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 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
-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
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
CONFIG ‘ A ’ CONVENTIONAL MBA (10 APERTURES INCL. TRACKING)
RX
RX
Potter
Horns
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
TX/RX
TX/RX
TX/RX
TX/RX
DUAL - BAND MED. EFF. HORNS
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
CONFIG ‘ A ’ CONVENTIONAL MBA (10 APERTURES INCL. TRACKING)
RX
RX
Potter
Horns
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
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
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
CONFIG ‘ A ’ CONVENTIONAL MBA (10 APERTURES INCL. TRACKING)
RX
RX
Potter
Horns
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
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
TX/RX
TX/RX
TX/RX
TX/RX
DUAL - BAND MED. EFF. HORNS
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 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
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 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
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
-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
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
• 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)
(shaped or parabola)
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
(shaped or parabola)
Stepped ring n
(n=1 to N)
(shaped or parabola)
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
80" reflector 80" plus 5" ring 80" plus 10" ring coverage coverage plus PE
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
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”
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
Wild Blue : EIRP Contour (56 Beams, 14 Gateways) (beam spacing = 0.35º)
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
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
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
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
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
Wild Blue : EIRP Contour (56 Beams, 14 Gateways) (beam spacing = 0.35º)
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)
Ka-band beam pattern
10
15
20
25
30
35
40
45
50
-3 -2 -1 0 1 2 3
Dir
ect
ivit
y (d
Bi)
Azimuth (deg)
Ka-band beam pattern
Ku-bandEuropecoverage
B#1
B#2
B#3
B#4
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)
Ka-band beam pattern
10
15
20
25
30
35
40
45
50
-3 -2 -1 0 1 2 3
Dir
ect
ivit
y (d
Bi)
Azimuth (deg)
Ka-band beam pattern
Ku-bandEuropecoverage
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)
Ka-band beam pattern
10
15
20
25
30
35
40
45
50
-3 -2 -1 0 1 2 3
Dir
ect
ivit
y (d
Bi)
Azimuth (deg)
Ka-band beam pattern
Ku-bandEuropecoverage
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
Ku-Band Brazil Tx/Rx
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
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
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
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
NA
NANC
NB
Ka-Band
Tx/Rx
45” Gregorian
Combined into one
WestEast
North
South
Ku-Band
North America Tx/Rx
100” Reflector
Ku-Band Brazil Tx/Rx
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
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
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
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
NA
NANC
NB
Ka-Band
Tx/Rx
45” Gregorian
Combined into one
WestEast
North
South
Ku-Band
North America Tx/Rx
100” Reflector
Ku-Band Brazil Tx/Rx
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
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
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
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
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
fd = 1 GHz*0.06 inches
≈ 65 volts
≈ 510 volts
Fundamental Mode 1/2 cycle
Odd multiples of one half cycle
3/2 cycle
fd = 1 GHz*0.06 inches
≈ 65 volts
≈ 510 volts
Fundamental Mode 1/2 cycle
Odd multiples of one half cycle
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