Kranthi Kumar Andhe The simulated plot gives the computed value. The measured data is giving 'power' values for the two planes.

You need to compute the axial ratio from the measured values for comparison with simulated values. You may need to verify that both are 'power' or 'intensity' ratios for a meaningful comparison.

The simulated axial ratio is calculated based on the magnitudes of two orthogonal linear polarizations including the phase difference between them (check the equation for the axial ratio). The measured data only includes the magnitudes of the power received for two polarizations. From this data you cannot calculate the axial ratio since you also need to know the phase difference between the two linear polarizations. However computing the difference between the two powers (|Power_Eplane - Power_Hplane|) can give you an idea of what the axial ratio is but it won't be exactly the axial ratio you're looking for to compare with simulations.

Mohamed K. Emara is mostly right, but even the ratio of powers can't tell you much about the axial ratio, except that the axial ratio cannot be better than the ratio of the powers. If the two powers are the same you could have anything from circular polarization of axial ratio = 1, or linear 45 degrees polarization of axial ratio infinity.

If you look at your results at 4.5 GHz, 6 GHz, 7.5 GHz and 9 GHz you will see that except at 4.5 GHz the measured axial ratio is worse than simulated, so the simulated axial ratio has not been achieved. It is not possible to tell if it has been achieved at 4.5 GHz.

In the chart in the spreadsheet, where the blue points are above the red dots the measured axial ratio is worse than simulated. When they are below or the same you can't tell.