hirobumi saito - dlr portal · compact x band synthetic aperture radar on 100kg small satellite...
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Compact X band synthetic aperture radar on
100kg small satellite
Hirobumi Saito
Japan Aerospace Exploration Agency (JAXA), Institute of Space and Astronautical Science (ISAS),
IAA Small Satellite Berlin
Conventional SAR Satellite and Proposed 100kg SAR Satellite
TecSAR 300kg Resolution 1m
NovaSAR-S 400kg Resolution 6m
TerraSAR-X 1230kg Resolution 1m
Proposed MicroXSAR 100kg Resolution10-3 m Stowed 0.73m $10-20M.
3m
3m
5m
0.7m
RadarSat-2 2200kg Resolution 3m
15m
What Happens if $20M SAR Sat Available ?
・ Now - Only developed country governments can own $ 100s M SAR Satellites for Security & Gov. Use. ・ If $20M SAR Satellite available - Private companies & developing countries own SAR Sat for disaster monitering & business. - Frequent SAR observation with Constellation. “Anytime, anywhere Earth Imaging”
Scaling of SAR Observation
• Radar Equation
• Synthetic Integration Time • SNR per One Pixcell • (NESZ, Resolution) vs (RF Power, Antenna Size, wavelength)
ss
TXRX LR
AGR
PP 22 44 πησ
π=
.2 azst
D vRTδ
λ=
.8 3
22
stso
raveTXimagevNFLkTR
APSNRλπ
ση δ°= −
223 )()8(
ηλπσ
APNFLvkTR
aveTX
sstorNE
−
=° δ
NESZ, Resolution, Satellite Size NESZ x Resolution ∝ λ /(RF Power x Ant
Area2) σNE
0δr ∝ λ/ PTX A2 SAR Performance Satellite Size
⇒Short Wavelength SAR is Suitable for Small Satellite .
100 300 1000 (kg)
10m
3m
1m
S(3GHz) X(9GHz)
C(5GHz)
L(1GHz)
ASNARO2 TecSAR
SAR-Lupe TerraSARX
Nova SAR
KOMSAT5
ALOS2
Cosmo-SkyMed
RADARSAT
JERS-1
ALOS
Satellite Mass
Reso
lutio
n at
σ0N
E =
-20d
B
-15dB
σ0NE= -20dB
MicroXSAR
Short Wavelength SAR is Suitable for Small Satellite .
σNE0δr ∝ λ/ PTX A2
SAR Performance Satellite Size
SAR System Specification for 100kg Satellite (Ground Resolution = 3 or 10m)
7
SAR System Block & Technology Strategy
Flexible Solar Panel
High – Speed X – band Transminitter
Deployable Antenna Feeder
RF Receiver
Data Processing & Storage
Li-Ion Bat
RF Transmitter
High Efficiency GaN Amp
Noncontact Wave Feed
Single Layer Slot Array
High – Rate Discharge Battery.
Thermal Management for High Peak Heat
500 Mbps Down Link for Small Satellite (Hodoyosh in 2014)
Flash Memory & Commercial FPGA
Flexible Solar Cell on backside of Antenna
Satellite Body
SAR Antenna.
Power & Heat
RF Amp.
Digital
Data Down Link .
Rectangular, Slot Array Antenna with Waveguide Feeder
Antenna size 4.9m x0.7m
Feeding Waveguide to three Panels
Feeder Waveguide
Satellite Body Deployed 3 Panels
Tournament Circuit
11
Honeycomb Single Layer Slot Array Antenna
Antenna Pattern
Ant Efficiency 55% Gain36.6dBic
One Polarization Antennal Dual Polarization Antenna being Tested Feeded from Both Sides Symmetric Pattern
Antenna & Feeder Composite Panel
-90 -60 -30 0 30 60 90-50
-40
-30
-20
-10
0XZ Plane
θ [deg]
Nor
mal
ized
Am
plitu
de [d
B] RHCP
LHCP 19.01 dB
9.6 9.65 9.731
32
33
34
35
36
37
0
1
2
3
Frequency (GHz)
Dire
ctiv
ity, G
ain
(dBi
c)
30%
40%
50%
60%
70%
80%
Directivity without back panel Directivity with back panel Gain (5.82 m) Gain (16.85 m) Axial ratio with (16.85 m)
Axial Ratio (dB)
RHCP LHCP
Noncontact RF Feed with Choke Flange at Hinge Position
・Waveguide Feeds RF to Deployable Antenna Panel ・Choke & Cover Flange at Hinge Position ・ Low RF Loss (<0.1dB) with Gap 1-2mm
λg/4
λg/4
short
open
Choke Flange Cover Flange Gap between Flanges (mm)
RF L
oss (
dB)
13
Deployed Antenna Needs Surface Accuracy of λ/20
Thermal Deformation Analysis
Deployment Mechanism (patented) smooth on antenna surface Angle Accuracy
Deployment Test with Air Bearings
Flexible Solar Cell on Back Side Thermally Isolated with Antenna by MLI
Stow
Deploy
14
GaN HEMT Pulse Amp 100/200W (Commercial)
600-1000W Amplifier 100/200W x 6 RF Combiner
600-1000W Power Combiner Input :Microstrip Line Combiner :Circular WG Resonator Output: Waveguide
600W Output Combiner
Φ27mm x 3mm
100/200W Input x 6
Measuement Heat Management
60W 5min
Module
15
SAR Data
Pluse Sharping Filter
Pre- Distortion D/A RF Amplifier
Ground Demodulator
SCCC Turbo Decoder S/X Dual Band 3.8m Parabola
SAR Data
Com Parameter Bit Rate 3480Mbps Orbit 600km RF Trans, Power 2W RF Power 22W RF Bandwidth 150MHz@8GHz Modulation 1 6QAM/64APSK Onboard Antenna MGA(15dBi) Ground Antenna dia 3.8m
500Mbps (64APSK) Down Link for 50kg Satellite Demonstrated in Hodoyoshi #4
Small Ant MGA/ Isoflix
Satellite
Ground Antenna
X band Transmitter
Hodoyoshi #4 in 2014
1.3kg, 22WDC, 2WRF, GaN Amplifier 2.5 oversampling parallel processing
Soon 64APSK 500Mbps
Demonstrated 16QAM 348Mbps
Conceptual Design of 100kg SAR Satellite Based on SDS-4 , 100kg Satellite at JAXA
Rocket H2A ALOS3 piggy - back
Orbit 618km, Sun – Synchronous, inclination 98°, 10:30@d.n.
Mass 100kg
Size 70x70x70cm3(with rocket), 4.6m x 0.7m (antenna in operation)
SAR Observation Strip-map Mode, Resolution 3~10m @NESZ=-15~-20dB, 5-10 min observation in a orbit, 460W DC for observation
SAR Antenna 4.6m x 0.7m, deployable system of single layer slot array panel x 6 non-contact waveguide feeding
Power 400W generation by flexible solar panel on antenna backside , Li-Ion 2.7Ah(Bus), 5.6Ah(SAR 3C fast discharge )
Attitude Control 0.06deg accuracy for SAR, coarse tracking for down link station, coarse sun-pointing for other period
Communication S band for TT&C, X-band 500Mbps
Data Storage 100 GB, Read 400Mbps
100kg SAR Satellite Block Diagram & Layout
図e-3-2 衛星の搭載機器配置の一例
Conclusions 1. We start development of small SAR compatible with
100kg satellite. 2. Applications are constellation (>10 Sats) with short
revisit time for natural disaster & ocean monitoring for Asian countries, and real time earth image from space.
3. Technologies: deployable single layer slot array antenna, non-contact waveguide feeding, GaN pulse amplifier Power & heat management
Outlook of SAR Satellite
図8 検討中の多偏波合成開口レーダを搭載した100kg級衛星の概観図。ロケット収納時(左上)と軌道上で合成開口レーダアンテナを展開した状態(右下)。
Slot Array Antenna
Waveguide Feed & Flexible Solar Panel
Specifications of 100 kg – Class SAR Satellite
Vehcle H2A Piggy-Back
OrbitAltitude 618km, Sun-Synchronous,Inclination 98°, 10:30@Desending Node
Mass 100kg(120kg with Separation Gear)Size 0.7mx0.7mx0.7m Stowed in Rocket
4.6mx0.7m Antenna DeployedSAR Observation X-band, Compact Polarimetric (TX: R, RX: R and L)
Strip-Map / Spot-Light ModeResolution 3~10m @ NESZ=-15~‐20dB5 min per revolution, 460W Consumption
SAR Antenna4.6m x 0.7m, Single Layer Slot-Array Antenna3 panels x 2 WingsNon-Contact Waveguide Feed
PowerThin Film Solar Panel at Antenna Rear210 W generationLi-Ion 2.7Ah (Bus), Olivine-type 5.6Ah(SAR)
AttitudeTarget Pointing:Pitch 0.06°,Maneuver 1°/sData Down Link & Sun Pointing:5deg
CommunicationsSatellite Operation S bandData Down Link X band 320Mbps
Data Storage100Gbytes, Write Speed :150Mbps x 4channelRead Speed :100Mbps x 4 channel
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