Carpet & Window

Radar was only half the story of electronic war. The other half was "counter-radar"--that elaborate series of Allied tricks and dodges to gum up the enemy's radar. Secret until last week, counter-radar had cost the U.S. more than $300 million. But it saved many times that amount in ships and planes. -Headquarters for counter-radar was Harvard's Biological Laboratory. The lab's peacetime monkeys and pickled dogfish were replaced by a regiment of electronic engineers. Their job was to poke fingers into enemy radar eyes. To get in practice for far-off German and Jap radars, the Harvardmen picked on the Radiation Lab at M.I.T., a mile away. The bitter war raged across the roofs of Cambridge.

Counter-radar licked Japanese naval radar, but its toughest enemy was the enormous radar network the Nazis spread over Europe. German coastal radars watched for Allied ships and planes. Thousands of inland "Wurzburgs" (radars shaped like giant electric heaters) aimed the Nazis' antiaircraft guns with fiendish precision. If the Wurzburgs had not been scotched by counter-radar, they might well have defeated Allied bombing.

Counter-radar attacked radar's fundamental weakness. The waves radar sends out must be reflected from a target before the target can be spotted. These reflected waves are so feeble that a weak or distant transmitter on the same frequency can "jam" them out. Counter-radar is a variety of jamming.

One type of jammer, called "Tuba," shot mighty blasts of radio interference from the bluffs of southern England. When British night bombers streamed home from raids, Tuba's beam was a sheltering arm reaching out from home. Within its protection, bombers were safe from Nazi fighters. Nazi radar scopes showed nothing but Tuba's enormous blur.

Tuba was not much help to U.S. day bombers, whose tight formations, necessary for protection against day fighters, made them extremely vulnerable to radar-pointed ground guns deep in Germany. So U.S. bombers carried "Carpet"--small transmitters sending out continuous waves to confuse the Wurzburgs. Carpet cut U.S. daylight bomber losses in half.

Tinsel Snow on Europe. Another effective countermeasure was "Window": strips of aluminum foil tossed into the air from planes. Two ounces of it looked to enemy radar like an entire bomber. The British first used Window during the 1943 raids on Hamburg. Cried the Nazi gunners, as swarming puffs of Window spotted their radar scopes: "The planes are doubling themselves!"

With counter-radar in full swing, a major raid on Europe became a complex business. Decoy planes dropped streamers of Window, filling the scopes of the Nazis' early-warning radars with swarms of imaginary bombers. From the cliffs of England, Tuba boomed its blasts, adding to the confusion. As the column of bombers swept toward Germany, Carpet cheeped from every plane, dazzling the Wurzburgs, while more puffs of glittering Window covered the sky with phantoms.

The U.S. produced 20,000 tons of Window, which decorated Europe with brilliant tinsel. The Nazis never found an answer, though they desperately offered a 700,000 Reichsmarks reward to German inventors.

This file is automatically generated by a robot program, so reader's discretion is required.