How to plot radiation pattern with S21 value

Hi,

For plotting radiation pattern we have to take the amplitude level for different angles. Then by using polar plot plot amplitude Vs angle.

Sudan

Is it using S21 values or what values? how to do get the aplitude using s21 values?

Would be a relative measurement. Record the S21 for a particular frequency and particular DUT position. Rotate the DUT with an angle (let's say 15 degrees). Record the new value of S21 for the same frequency....and so on, until reach 360 degrees.