I am working in MATLAB with measured data from a VNA. The bandwidth is 1 GHz from 5-6 GHz with 801 samples in the frequency domain. Everywhere I have read that I need to split the data into 2 parts at N/2 and then insert zeros. But as I have an odd number of samples, should I insert zeros before or after the middle sample? Another thing is I am actually getting better time domain results after appending zeros at the end of the data, which is a strict no-no wherever I read. Anyone know the reason for this? Thanks.