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Axial ratio and cross polar discrimination (XPD) interference

For circular polarisation the purity of the polarisation is specified in terms of axial ratio.

To obtain the cross polar discrimination (XPD) interference refer to the following formula:

XPD = 20 log ((r+1)/(r-1)) dB.

Axial Ratio AR (dB) Axial Ratio r (number) XPD (dB)
0.3 1.0352 35.24
0.34 1.04 34.15
0.42 1.05 32.26
0.51 1.06 30.71
0.59 1.07 29.42
0.60 1.0714 29.25
0.67 1.08 28,3
0.75 1.09 27.32
0.83 1.1 26.44
0.98 1.12 24.94
1.01 1.123 24.74
1.06 1.13 24.29
1.14 1.14 23.69
1.21 1.15 23.13
1.36 1.17 22.12
1.58 1.2 20.83

Last amended 2 July 2008, 10 Feb 2015