Editing the excitation signal

I'm altering the excitation signal in the SEFT tutorial from a sinusoidal(default) signal to a custom signal. If I select a user defined equation such as: sin(2pi0.75E9*_t) it make the whole simulation crash with error 'Field sensors cannot record in frequency domain with user defined sources. Please change to time domain recordings only.'

How do I fix this? Or what is the best way to create a custom unipolar pulse?

I'd like to enter f(x) = 0.5sin(2pi0.75E9_t) + 0.5abs(sin(2pi0.75E9_t))

I think your signal was fine, but your settings for the Field Sensor need to be changed.