Understanding the Role of Diffraction in Signal Interference | Explained Simply

[dervast]

Hi i am wondering how the diffraction interferes with the signals.. I was reading wikipedia's diffaction artiocle .. bt i can't understand clearly what diffraction causes to an e/m wave.. What i know is that the diffraction is bad some times os some other times is good because we can send waves using diffraction with the Earth's surface...

 

[Astronuc]

The problem arises with destructive interference. If two radiowaves have the same frequency, but are 180° out of phase at some point, then the combined radio signal will be nil, and a radio at that location will be unable to reproduce the radio transmission.

One can see diffraction patterns with visible light with alternating bright and dark lines or concentric rings corresponding to linear (line) or concentric circular diffraction gratings.