From lighthouse-like 72X to Type 72DM

The early equipment worked like a radio lighthouse, using a rotating transmitter and parabolic reflector timed by a precision chronometer. The Type 72X occupied the masthead inside a large wooden cylinder. Wartime radar needed that commanding position, so the beacon had to move. In the Type 72DM, the radiating equipment, reflector, and transmitter rotated bodily around the lower foremast. The redesign shows how radar reshaped the physical arrangement of a carrier's other electronics. A wider frequency range also helped aircraft distinguish among several carriers operating together, reducing the chance that they would home on the wrong ship. A mistaken landing was manageable, though naval planners still wanted each air group to recover to its own carrier.