My digital system has no radiated emission issues as its clock frequency is only 10 MHz

The origin of radiated emission is a signal source at a certain frequency combined with a radiating antenna. The amount of energy in a square wave is mainly defined by the amount of power in its fundamental frequency. However, the band – in which powerful harmonic frequencies are present – are mainly defined by the rise and fall times, which mainly depend on the driver technology used.

If you take into account that a trace of 3,75 cm is a possible quarter wavelength antenna at 1 GHz on FR4, it’s clear that even an 8-bit microcontroller can cause high frequency radiated emission.