I didn’t test displayport, but IIRC it’s digital, like HDMI is. So, my guess is that Displayport also emanates lots of EM interferences. The very sharp nature of squarey digital waves (in contrast to a sinusoidal wave from analog) decomposes into high-frequency interferences (because a square wave always has high frequency components, as observed through FFT). That’s what causes UHF interference.
I didn’t test displayport, but IIRC it’s digital, like HDMI is. So, my guess is that Displayport also emanates lots of EM interferences. The very sharp nature of squarey digital waves (in contrast to a sinusoidal wave from analog) decomposes into high-frequency interferences (because a square wave always has high frequency components, as observed through FFT). That’s what causes UHF interference.