Why in the attached image for a simple 3 point moving average that has been converted into a TF (z domain) is there a wired dip? It seems that when I change the sampling time, the dip shifts to the right. And why does the black veritable line at the end seem to be equal to $\pi/T$? It looks like the black line is $2x$ frequency of the systems bandwidth so I'm assuming it is related to the Shanon limit for sampling? In what world does the output to a moving average just suddenly cease to exist, or go to zero at the dip? The attached reference bode
I am in the 1st year of control stuff. Thanks for the help