planar antennas 1 - university of...
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Planar Antennas for CMB Polarimetry
Jamie BockTony Bonetti, Goutam Chattopadhyay, Peter Day, Sunil Golwala, Kent Irwin, Matt Kenyon, Chao-Lin Kuo, Andrew Lange, Rick LeDuc, Hien
Nguyen, Amy Trangsrud, Anthony Turner, Jonas Zmuidzinas
Jet Propulsion Laboratory
CMB Technology WorkshopBoulder CO, 25-28 August 2008
Principle of Operation
Silicon
AR Nb
μ-strip
Back-Illumination
Planar Antenna- Combine sub-slots coherently- Higher forward gain than single slot- E-field distribution defines beamshape
y-pol slots
x-pol slotsx-pol combining network
y-pol combining network
Combiner network
Implementation in a 150 GHz Device
Abs
orbe
r and
TES
Ban
dpas
sFi
lter
180˚
Hyb
rid
Measured Antenna Performance
Measured cross-polar response < 3 %New broad band design
Spectral Response and Optical Efficiency
Measured efficiencies range from 50 – 80 %
Results now for 100 GHz devices as well
35 % BW
Implementation in Focal Plane Arrays
Dual-Pol 150 GHz Pixel
8x8x2 Focal Plane Tile
512 Bolometer Focal Plane
Implementation in Focal Plane Arrays
A Very Flexible Technology
Extended Frequency RangeScale slot array and reroute combiner networkNo problems seen for low frequenciesSpace gets tight for ν > 250 GHz
Highly Tapered BeamsMake d/fλ largerChange combiner network to taper field amplitudeAccount for (known) slot-slot impedance matrix
Non-Telecentric BeamsChange combiner network to produce phase lag
Simultaneous Stokes I, Q & UAdd hybrid and use 4 detectors per pixel, balanced hybrids for band matching
Multiple Bands per AntennaDemonstrated with diplexer in one polarizationKeeping diffraction limit requires beam sharing
Overlapping AntennasIt is possible to recover perfect mapping speed (factor ~3 at 2fλ)Antennas must be large to use entire aperture
Advantages & Disadvantages
AR Coating is Very Simple
Coupling is Lithographic
Minimizes Focal Plane Mass
High Optical Efficiency
Polarized Beam Matching
Beam Control
Flexibility
Need Space for Detectors
Need Better Control of Defects
Advantages Disadvantages
Field focal plane arrays in CMB receiver
Focal plane array demonstration in a single band
Pixel demonstration in multiple bands
Pixel demonstration in a single band
Pixel demonstration in a single band
Pixel demonstration in a single band
Pixel demonstrations at ≤ 30 and ≥ 300 GHz
Field focal plane arrays in a CMB receiver
Pixel demonstration (completed at 100 and 150 GHz)
Milestone
Active device to switch polarization states, RF design
Antenna and combining network design, transmission line density and crossovers
Diplexer design doneDual-polarization design
Antenna and combining network design
Hybrid design and spectral band matching
Antenna and combining network design
Antenna and filter design
Process uniformity and reliability
Antenna and filter design,RF properties and losses
Technical Challenges
Noise stability
System sensitivity
System sensitivity
Use in non-telecentricoptical designs
Systematics control, depends on scan strategy
Sidelobe control for optics without a cold stop
Foreground removal
System sensitivity
Beam formation,polarization analysis,band definition
Advantage for CMBPOL
Polarization modulation
Overlapping antennas
Multiple frequency bands per antenna
Directed beams
Simultaneous Stokes I, Q and U
Highly tapered beams
Frequency coverage
Focal plane arrays
Optical coupling
Capability
2
1
4
2
Attributes Advantageous for CMBPOL
2
2
Attributes Necessary for Some CMBPOL Mission Designs
4
4
5
Attributes Necessary for CMBPOL
TRL?
Technology Readiness and Milestones
Focal Plane Sensitivity Budget
5Psat/QTES safety factor2d/fλBolometer pitch
4 yearsTlifeMission lifetime1.0 %εMirror emissivity at 1 mm
1.414Noise margin60 KToptMirror temperature
30 %Δν/νFractional bandwidth4 KTlensLens temperature
40 %ηoptOptical efficiency0.1 KT0Focal plane temperature
Detector Sensitivities
10
100
1000
10 100 1000
Freq [GHz]
NET
/feed
[uK
s1/
2 ]
Planck-LFIPlanck-HFITFCR-HEMTTFCR-boloEPIC-CSPerfect bolo
Noise Contributions
1
10
100
10 100 1000Freq [GHz]
NEP
[aW
Hz-1
/2]
CMBOptics/BaffleDetectorMarginTotal
EPIC
Sens
itivi
tyA
ssum
ptio
ns
T0 = 250 mK for the Inflation Probe?