Transmission line rule

[joniengr081]

A general rule of thumb regarding transmission line in FR4 is, if the length of a conductor is more than 1/10 of the wavelength, then we consider it a transmission line. I have calculated some numbers. Kindly let me know if they are correct.

Clock frequency: 500 MHz
Dielectric constant: 4
Wavelength: 300 mm
Turn in to transmission line: If the trace length is more then 30 mm

Clock frequency: 1000 MHz
Dielectric constant: 4
Wavelength: 150 mm
Turn in to transmission line: If the trace length is more then 15 mm

Clock frequency: 2000 MHz
Dielectric constant: 4
Wavelength: 75 mm
Turn in to transmission line: If the trace length is more then 7.5 mm