RADAR MAGIC

Evening Post, Volume CXL, Issue 39, 15 August 1945, Page 4

RADAR MAGIC

PART OF THE STORY

WONDERFUL DEVICES (By Telegraph—Press Association—Copyright.) Eec. 9 a.m. WASHINGTON, Aug. 14. British and American military and scientific leaders have released all that can at present be revealed about radar, including: the principles of instrument bombing. A transmitter sends out radio energy in intense bursts called pulses, travelling at the speed of light—lß6,ooo miles a second. These record on an instrument panel as a continuo'us line, which is called the time-base. When the pulses strike an object a radio echo is received and a vertical projection called a "pip" appears on the timebase line. The speed of the pulses being known, the distance between the beginning of the time-base and the pip indicates the range of the object. The directiori of the object from the transmitter is determined by noting the position of the antenna at the time the pip appears. The antenna sends out the pulses in a narrow beam like a searchlight, and can sweep through the circumference of a circle. With the latest type of radar the echoes draw a map on a cathode-ray tube, and no matter how many targets surround the radar set, or whether the set is on a ship, a plane, or the ground, each target is indicated by a blob of persistent light on the face, of the tube. The direction of these blobs from the centre of the tube indicates the range of the target. With bombing through overcast, a radar map of the unseen terrain ahead shows on the tube. This electronic map shows up everything within 300 miles. Large cities can be denned 50 miles away. TROUBLE FOR U-BOATS. Airfields, bridges, and other specified targets are magnified as the plane approaches. With ASV ("air t~> vessel") radar, a plane can detect surfaced submarines tens of miles away, and larger craft upwards of 200 miles. Operators say that ASV is so accurate that they can pick up even a ship's wake at a considerable altitude. This instrument contributed largely to the defeat of the U-boat wolf pack. The Nazis tried everything to outwit the searching beams of the radar, including the development of an instrument based on captured Allied radar. This instrument intercepted the Allied radar signals, thus giving the U-boats a chance to submerge. However, the Allies countered with new micro-wave radar. There was also a "tail warning," a radar fitted into planes which do not carry complete radar. When an enemy comes within 800 yards of a plane from behind, a bell rings and a warning light flashes. Radar cannot detect objects below the surface of the water, or much beyond the horizon. However, long-range navigation radar sends out from huge land stations signals which can be picked up 1200 miles out to sea, allowing ships to plot their positions. . Warships' radar is so sensitive that the instruments can trace projectiles in flight.