Polarization Calibration: Difference between revisions

Latest revision as of 12:54, 18 November 2016

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-== Linear to Circular Conversion ==
+[[Linear to Circular Conversion]]
-At EOVSA’s linear feeds, in the electric field the linear polarization, X and Y, relates to RCP and LCP (R and L) as:
-:<math> R = X + iY </math>
-:<math> L = X - iY </math>
-In terms of autocorrelation powers, we have the 4 polarization products XX*, YY*, XY* and YX*, where the * denotes complex conjugation.  The quantities RR* and LL* are then
-:<math> RR^* = (X + iY)(X + iY)^* = XX^* - iXY^* + iYX^* + YY^* </math>
-:<math> LL^* = (X - iY)(X - iY)^* = XX^* + iXY^* - iYX^* + YY^* </math>
-One problem is that there is generally a non-zero delay in Y with respect to X.  This creates phase slopes in XY* and YX* from which we can determine the delay very accurately.  As a check,
-:<math> Stokes I = \frac{RR^* + LL^*}{2} = XX^* + YY^*</math>
-:<math> Stokes V = \frac{RR^* - LL^*}{2} = i(XX^* - YY^*)</math>
-For completeness:
-:<math> Stokes Q = XX^* - YY^* </math>
-:<math> Stokes U = XY^* - YX^* </math>
-:<math> P_{linear} = \sqrt(U^2 + Q^2)
-== Polarization Mixing Correction ==
+[[Polarization Mixing Due to Feed Rotation]] ([[Polarization Mixing Correction (Old)]])
-Due to relative feed rotation between az-al mounted antennas and equatorial mounted antennas