Radar --- Radio Location
Revolutionizing detection and ranging
By Tom Doeppner, E.E. '44
On that so often quoted seventh of December, Private Joseph L. Lockard was scanning the skies over Pearl Harbor with a brand-new aircraft detection device. Even though he was just practicing, at 7:02 he noticed a deflection of the meters which could only be interpreted as the approach of aircraft. The meters also told him the location of the planes, the direction of their flight, and their distance from the shore - about 130 miles. A few minutes later, at 7:20, Lockard reported his discovery to a superior officer, who decided that these planes must be B-17's, expected from San Francisco. At 7:55, the Japanese Air Force hit Oahu. Radar had worked; the human mind had failed.
It has been said that the battle of the Coral Sea had been fought without any ship of either side being seen by its enemies; that it was a battle between planes and aircraft carriers. Maybe the ships and planes could not be seen with the naked eye or with telescopes, they were, however, detected long before their approach. It was Radar that did that job - Radar saw the planes approaching. Radar located the position of the ships. Radar detected their speed. Radar told which way they were proceeding. Radar to a great extent, determined the outcome of this and many other battles of World War II.
If these surprising results and revolutionizing methods of radar had been known or even anticipated by the authorities in the navy and war departments of twenty or even ten years ago, the inventors would have had an easier time and more financial aid. The immediate history of radar does not go very far back. Only in 1922, two scientists of the Naval Aircraft Radio Laoboratory, Dr. A Hoyt Taylor and Leo C.Young, made a fundamental discovery. They transmitted radio aves of ultra-short wave length and noticed the reaction of metal objects like ships on these waves. For several years, no more astounding discoveries were made in the field; however, the N.A.R.L. as well as other laboratories proceeded with careful scientific experiments and investigations in the field of ultra-high frequency. In the thirties, action on the development of radar was stepped up: in June, 1930, L. A. Hyland foresaw the possibilities of aircraft detection in the ultra-high frequency signals. He observed that an airplane which crossed the line between ultra-high frequency transmitter and receiver, caused an interference pattern which indication the plane's presence.
One year later, in June, 1931, the Radio Division of the U.S. Bureau of Engineering asked the N.A.R.L. to investigate the use of radio for plane and ship detection. Now, the ice was broken and even the Senate Appropriations Committee allotted funds for the project. With these aids, progress was made rapidly, and in October of the same year, proposals sent by the N.A.R.L. to the Bureau of Engineering were found to have practical possibilities. In January of the next year, the War Department got interested, and later that year, the Army examined apparatus by means of which planes could be detected at a range of fifty miles. Theoretical military application were outlined in 1933; 100,000 dollars were appropriated in 1935 for laboratory research. Then, as a first climax, on Rear Admiral Harold Bowen's initiative, radio-detective equipment was installed aboard the U.S.S. New York in 1938.
The tests performed aboard the battleship New York were decisive in the history of radar. If results obtained were poor, the Navy would lose interest in radar for a long time to come. The technical crew which went out on the New York was headed by Robert M. Page. A destroyer squadron had been assigned to make a torpedo attack on the New York after darkness, and radar was to find out the location of the destroyers and the time of attack. From about sunset on, Page and his men stood by their radar set and watched the horizon over an angle of 360 degrees. For several hours, nothing happened. Vice Admiral Alfred W. Johnson, the Atlantic Squadron Commander, appeared in the control room and finally lost his patience. He knew the approximate time of attack and feared that the destroyers might be approaching without being discovered. When Johnson was ready to leave, the first signal came in. "There it is," said the Admiral. The destroyers were discovered, even though still eight miles away. From that moment on, Vice Admiral Johnson was a radar enthusiast and did much toward boosting the development of radar.
The problem now shifted from a scientific one to a commercial one; it became difficult to build radar sets fast enough to supply ships with them and still keep the entire device a military secret.
Naturally, there has been done much research on similar devices in foreign countries as well. The British "Radiolocator" is older than our radar, and the factor it played during the air blitz on England in 1940 did much to stimulate the development and improvement of our radar.
It had to be expected that the enemy's armed forces would have similar devices, acquired either from American or English inventions, or, which seems more likely, through their own research. The first time that this became evident was in the case of the "Bismarck." After the Bismarck had hit the British cruiser Hood with surprising accuracy, she tried to escape the pursuing British planes. One of the British fighters located the Bismarck and guided other British aircraft in
for the destruction of the German. This British fighter was fired at and hit from the Bismarck at a time when it was still out of sight above the clouds. This fact can only be explained if the Bismarck was equipped with some sort of radio-detective device.