a square wave with 50% duty cycle should not have even harmonics only the odd ones. but in my simulation get all the harmonics(in violation of the theory shown in the last slide bellow)
T=102 ps => f_fundamental=9.Ghz
where is the problem?
No, this is correct. All the harmonics are 0V (look at the values on your plot), because your "square wave" is not a square wave - you have both the Voltage 0 and Voltage 1 being 0, and so it switches between 0V and 0V, and has no harmonic content at all. So there are no even or odd harmonics - all harmonics are 0.