Other contributors have said "What are the names of the men who estblished the eletomagntic wave theory?" is the same question as "Who were the two men that established the electromagnetic wave theory?" If you believe that these are not asking the same thing and should be answered differently, click here
Who were the two men that established the electromagnetic wave theory?
When a traveling wave is reflected, the reflected wave and incident wave can add to porduce peaks and nodes at different distances along the path. These are measures of the EM wavelength.