NEW RADAR RESEARCH SCHEME IS EXPLAINED

Press, Volume LXXXII, Issue 24816, 5 March 1946, Page 4

NEW RADAR RESEARCH SCHEME IS EXPLAINED

T. rpcpntlv announced by the Minister in charge of the Department of Sdentiflc and" Industrial Research the Hon. D G. Sullivan, that a special research in fundamental problems of radio and radar propagation was to be carried out in Mid-Canterbury. This account Sr the nroiect is written for “The Press by a correspondent who has ffitfrWewed officialss of the D.S.I.R. in Wellington and Mr T. R. Pollard? director of the Defence Development Section, D.5.1.R., based at Canterbury University College.

The principal object of this research is the investigation of the anomalous propagation of high frequency radio waves. Early in the history of radar, which uses very high frequencies, operators noticed that the performance of their radar sets varied considerably from day to day for no apparent reason. Research into the problem soon made it clear that the variation was caused outside the radar sets themselves and was in fact due to variations in the meteorological conditions of the lower few thousand feet of the atmosphere. Under certain conditions of the lower atmosphere, temperature inversion took place, giving rise to ducts or channels which, in turn, greatly affected the maximum range of a radar set. This condition of temperature inversion is often brought about by the presence of dry hot winds. It is a condition very similar to that of the “mirage.” commonly observed, in which an object such as an island, normally below the horizon and hence out of sight of the observer, becomes visible for short periods. Those who have made daylight crossings to and from Wellington have possibly noticed this condition along the coast between Cape Campbell and Kaikoura. It will be realised that, during the war period, information of this type was vitally necessary for the Allied forces in estimating the range of their own and the enemy’s radar sets. Investigations were carried out in the Allied countries. However, at the end of the war, there was still much to be discovered. The initial cause of this anomalous propagation is a meteorological one and thus involves the weather itself. Early Research in New Zealand New Zealand’s part in the research commenced in October, 1944, when a team of scientists from the Radio Development Laboratory of the Department of Scientific and Industrial Research carried out a short-term series of experiments with special equipment for investigating the lower atmosphere. This equipment was lent by a scientist from the United States National Defence Research Committee. The site chosen for the experiments was the Kaikoura Peninsula. In November, 1944, Dr. H. G. Booker, of the Telecommunications Research Establishment (the main R.A.F. radar research establishment in the United Kingdom), visited New Zealand, and was impressed with the possibilities of Mid-Canterbury as a site for long-term experiments in radio meteorology. Canterbury was selected because of its exposure to north-west winds. These, technically known as Fohn winds, cause radar installations on the coast to give abnormal ranges on some targets. Once' able to forecast the conditions which cause radar abnormalities (anomalous propagation), the Allied forqes would have been able to foretell not only the range of their own radar equipment but also the limitations of enemy equipment. At the end of 1944, when the end of the war against Japan was not in sight. Allied scientists believed that very similar effects to those in Canterbury, with Fohn winds, would be experienced off the east coasts of China and Japan. According to leading scientists in Britain and America, MidCanterbury offered an ideal natural laboratory for experiments in the relation of meteorology and radio propagation. It was then (in 1944) the only area in Allied hands where the experiments could be made, With' reasonable hopes of success in a short time.

Plans went forward rapidly, with the co-operation of America and Britain. The urgency of the problem, for operational reasons, disappeared after V-J Day; but, on the suggestion of British scientists, it was decided to continue with the experiments of the “Canterbury Project”—as the scheme came to be known—on a peace-time basis.

Radar, developed primarily to meet a war ,emergency, is now to be put on a peace-time footing. Instead of guiding the planes and ships of war, it will in future aid the safe passage of merchant ships and civil aircraft. The MidCanterbury research project, originally planned as part of radar’s war-time development, will assist in its adaptation to peace-time uses. While emphasis has been placed on the value of the research in radar de-» velopment, the project will also have an important bearing, in its findings, on ultra-high frequency communication, radio navigational aids, and television. At times, the meteorological conditions of the lower atmosphere affect all radio waves of similar frequencies to radar. Besides giving further information on problems of radar and radio, the project will yield data, of great value to meteorologists, on the Canterbury nor’-westers. This may assist materially in the preparation of more accurate weather forecasts. The work is being organised by the Dominion Physical Laboratory of the Department of Scientific and Industrial Research. The headquarters will be at the now disused Ashburton aerodrome, and about 34 scientific personnel will be involved. They will work in close co-operation with the Defence Development Section at Canterbury Universitv College and also with the New Zealand Meteorological Department. Communication facilities will be Erovided by the Post and Telegraph •epartment. Teams of Observers The purpose of the experiments will be to try to formulate fundamental laws connecting the behaviour of ultra-high frequency radio waves with the types of meteorological conditions experienced during a Fohn wind. To do this, it will be necessary to collect extensive data on both these subjects simultaneously. During nor’-west weather, three teams of observers from Ashburton will go out into the surrounding countryside to take meteorological “soundings” in the lower atmosphere—measuring the temperature, humidity, and wind velocity. A Navy minesweeper, specially modified for the purpose, will operate off the coast, with a fourth team of “sounders” aboard. The observers will continue with their work, day and night, so long as Fohn wind conditions last. Two aircraft, based on Wigram, will also be employed during the day to secure further meteorological information. Data on ultra-high frequency radio propagation will be obtained from three radar sets situated on the coast three miles north of the mouth of the Ashburton river. Special equipment on the minesweeper and aircraft will measure the strength pf radar signals from these sets. The operations of the observers will be controlled by a scientist at the Ashburton aerodrome, where the data collected will be analysed, by a team of mathematicians and scientists. The observations will continue for a year from next April, and will cover a big area of the Canterbury plains, as well as up to 100 miles off the shore. It is hoped to gain knowledge which will benefit not only New Zealand, but the' whole world.