H2X

H2X, eventually designated as the AN/APS-15,[2] was an American ground scanning radar system used for blind bombing during World War II.

This shorter wavelength gave H2X higher resolution than H2S, allowing it to provide usable images over large cities which appeared as a single blob on the H2S display.

All of these were replaced in the post-war era with systems customized for the jet powered strategic bombers that entered service.

H2X used a shorter 3 cm "centimetric" wavelength (10 GHz frequency) than the H2S, giving a higher angular resolution and thus a sharper picture, which allowed much finer details to be discerned, aiding in target identification.

[7] H2S subsequently also adopted 3 cm in the Mark III version entering operational service on 18 November 1943, for "Battle of Berlin").

The first H2X-equipped B-17's arrived in England in early October 1943, and were first used in combat on 3 November 1943 when the USAAF VIII Bomber Command attacked the port of Wilhelmshaven.

The ventral hemispherical radome for the H2X's rotating dish antenna replaced the ball turret on B-17 Flying Fortress Pathfinders, with the electronics cabinets for the "Mickey set" being installed in the radio room just aft of the bomb bay.

A further twelve PR Mk.XVI Mosquitos of the 25th Bomb Group (Reconnaissance) of the Eighth Air Force were fitted with H2X and beginning in May 1944, flew radar mapping night missions until February 1945.

French-language diagram of H2X displays and equipment
The H2X's resolution was enough to produce good images of other aircraft, in this case, another B-17 Flying Fortress flying below the radar-carrying aircraft.