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APC Cross Polariza,on Couplings 3rd
Stokes Parameter
Thomas Meissner and Frank J.
Wentz , Remote Sensing Systems
Presented at Aquarius Cal/Val
Web-‐Workshop January 29 – 30,
2013
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Antenna Pa8ern Correc,on (APC)
𝑻𝑩 𝑻𝑶𝑰=𝑨∙𝑻 𝑨 𝑬𝒂𝒓𝒕𝒉
𝐴=█■𝑎𝐼𝐼&𝑎𝐼𝑄&𝑎𝐼𝑈@𝑎𝑄𝐼&𝑎𝑄𝑄&𝑎𝑄𝑈@𝑎𝑈𝐼&𝑎𝑈𝑄&𝑎𝑈𝑈
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APC Matrix
V1.1 -‐ 1.3: Quick Fix
Off-‐diagonal terms set to zero,
Except 1st leaking to 3rd set
to remove overall bias in 3rd.
GRASP paTerns March 2012 Results
of orbit simulator (least square
fit of simulated TA to TA
= A-‐1 ·TB).
horn 1 1
1.0300
0.0000 0.0000
2
0.0000 1.0795
0.0000 3
-‐0.0032
0.0000 1.0433
horn 2 1
1.0338
0.0000
0.0000 2
0.0000
1.0977 0.0000
3
0.0000 0.0000
1.0658 horn
3 1
1.0420 0.0000
0.0000 2
0.0000
1.1175
0.0000 3
-‐0.0057
0.0000 1.0999
horn 1 1
1.0448
-‐0.0383 -‐0.0039
2 -‐
0.0030 1.0786
0.0310 3
-‐0.0001
-‐0.0258
1.0755 horn 2
1
1.0497 -‐0.0343
-‐0.0074 2
-‐0.0006
1.0593 -‐0.0156 3
-‐0.0027
0.0111
1.0555 horn 3
1
1.0580 -‐0.0344
-‐0.0116 2
-‐0.0004
1.0485 0.0071
3
-‐0.0032 -‐0.0148
1.0489
Adjusted x-‐pol for IU and QU
in V 1.3.5.
horn 1 1
1.0448
-‐0.0383 +0.0500
2 -‐
0.0030 1.0786
+0.0300 3
-‐0.0009
-‐0.0258
1.0433 horn 2
1
1.0497 -‐0.0343
0.0000 2
-‐0.0006
1.0593
0.0000 3
-‐0.0067
0.0111 1.0555
horn 3 1
1.0580
-‐0.0344
+0.0250 2
-‐0.0004
1.0485 +0.0300
3
-‐0.0045 -‐0.0148
1.0489
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3rd Stokes Cross Polariza,on Couplings:
aIU and aQU
1st Stokes I = V + H
(lee) 2nd Stokes Q = V –
H (right) The figure
shows measured – expected at
TOI as func,on of 3rd Stokes
U for APC matrix derived from
GRASP March 2012 pa8erns without
any adjustments.
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3rd Stokes Cross Polariza,on Coupling:
aQU
V1.3 GRASP March 2012 >
V1.3.5
The upper panel shows asc –
dsc map for Q (2nd Stokes)
measured – expected. The lower
panel shows asc – dsc
for U. November 2011.
DoTed line: magnejc equator
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3rd Stokes Cross Polariza,on Coupling:
aIU
V1.3 GRASP March 2012 >
V1.3.5
The upper panel shows asc –
dsc map for I (1st
Stokes) measured – expected.
The lower panel shows asc
– dsc for U. November
2011. DoTed line: magnejc
equator
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3rd Stokes Calibra,on
• No adjustments of aUU and aQU
were done. • Only adjustment of
aUI to fix small bias during
S/C pitch maneuver. • Effecjvely
absorbs gain factors in calibrajon
of 3rd Stokes. • New paTerns
show consistency in 3 diagonal
values aII, aQQ, aUU during S/C
pitch
maneuver.
𝑈𝐵 𝑇𝑂𝐼=𝑎 𝑈𝐼∙𝐼𝐴+𝑎 𝑈𝑄∙𝑄𝐴+𝑎 𝑈𝑈∙𝑈𝐴
GRASP March 2012 > V1.3.5
horn 1 3
-‐0.0001 -‐0.0258
1.0755
horn 2 3
-‐0.0027
0.0111 1.0555
horn 3 3
-‐0.0032 -‐0.0148
1.0489
horn 1 3
-‐0.0009
-‐0.0258 1.0755
horn 2 3
-‐0.0067
0.0111 1.0555
horn 3 3
-‐0.0045
-‐0.0148 1.0489
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S/C Pitch Maneuver
( ) ( )( ) ( )
2 2
3 3/
Faraday geometric
Faraday geometric
geometric Far
cos 2 sin 2sin 2 cos 2
=
Polarization Basis Rotation AngleNormal operation:
S/C pitch manuever:
B B
B BS C Earth
T TT T
ϕ ϕ
ϕ ϕ
ϕ ϕ ϕ
ϕ ϕ
ϕ ϕ
−⎛ ⎞⎛ ⎞ ⎛ ⎞= ⋅⎜ ⎟⎜ ⎟ ⎜ ⎟
⎝ ⎠ ⎝ ⎠⎝ ⎠
= +
?? aday
Faraday
geometric
computed from
Total Electron Content (TEC) maps computed at geolocation
ϕ
ϕ
3rd Stokes corrects TB for
Faraday Rotajon through ionosphere.
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S/C Pitch Maneuver: 3rd Stokes
measured vs calculated
• Very good alignment during pitch
maneuvers: ― Diagonal element aUU
and 3rd Stokes calibrajon o.k.
― We made small adjustment of
aUI to remove overall bias.
• Sjll need to do: 3rd stokes
measured vs. calculated for normal
operajon: ― Use IGS TEC maps
to calculate 3rd Stokes.
