I am designing a ultrawide band transmitter which emits short pulses.To decide how long for a trace can be counted as transmission line,I need to know the wavelength of the pulses.
These are periodic Gaussian pulses of period 100ns.Pulse duration is 1ns.Two possible thoughts are:
1 Since the Fourier Transform of a single pulse have a central frequency of 4GHz and bandwidth of 2GHz,wavelength is light speed in medal(copper)/4Ghz.
2 Since wavelength is the distance of pulse travels in one period,it will be pulse duration*light speed in medal.
Obviously these two are different.
Please help me.

Thanks a lot!

 

If you want to preserve the shape of the pulse, you use the highest frequency, which is determined by the pulse duration.