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Radar origins

Page history last edited by Ian Gillis 3 years, 3 months ago

 

Latham

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Introduction

One of Colin Latham's series of articles for the MRSL newspaper "News and Views" very clearly expounds the rationale for substantiating the claim of Britain to be the first successful developer of radar into an operational defence system and as this is frequently disputed by some commentators I believe it is worth highlighting as part of our History. The article was written circa 1987 but is just as relevant today

 

R for Radar

 

In arriving at the letter 'R' I would like to look at the key word itself and to discuss some misconceptions about Britain's part in its development.

 

In Britain, where the main thrust of the original work took place - and I will come to that later - the technique of locating objects by the reflection of radio waves was first known as RDF, for 'Radio Direction Finding' and later, from an official public announcement on 17th June 1941, as 'radiolocation'. This was a very satisfactory name and many people then engaged upon it felt a sense of disappointment when, in 1943, it was superseded in this country by the American term RADAR.

 

It appeared at first to be an ugly word, although one had to admit the sensible derivation from 'RAdio Direction And Ranging' as well as its palindromic construction which gives a clue to the essential two-way nature of the reflected radio signal. Anyway, like it or not, 'radar' has become the universally adopted term and is now used, I believe, in most languages of the world.

 

I regret to see that recently there has been a tendency in some columns of the national press to publish articles and letters which diminish Britain's leadership in radar during the last war. It is as if a new generation has just learned, with great surprise, that Germany also was well-advanced in radar techniques in the war, and that the basic principles had been expounded long before that in many other parts of the world.

 

From these 'revelations' it now appears to be fashionable to allocate the primary credit anywhere but where it truly belongs; namely, to the engineers, scientists and Service personnel of this country. It was they who did the most important thing: they made it really work and, with American help, laid the foundations for the present world-wide industry.

 

By the mid-thirties radio communication was well established on a global scale. Large industries had been built up in many countries to meet the demands for equipment for domestic entertainment and for the radio services required commercially and for defence. The phenomenon of reflection of radio signals was commonly observed: indeed it would have been strange if no one had commented upon it nor speculated on how it might be used to locate distant objects. Marconi himself was one of several who drew attention to the effect, commenting as follows in a lecture to the American Institute of Electrical Engineers in 1922:

 

'In some of my tests I have noticed the effects of reflection of these waves by metallic objects miles away. It seems to me that it should be possible to design apparatus by means of which a ship could radiate or project a...beam of these rays in any desired direction, which rays if coming across a metallic object, such as another steamer or ship, would be reflected back to a receiver.. .on the send­ing ship, and thereby immediately reveal the presence and bearing of the other ship in fog or thick weather.'

 

Experimental work was carried out in many parts of the world during the 'twenties and 'thirties with varying degrees of success and, as is often pointed out, the French liner Normandie was equipped with iceberg detecting equipment which relied upon reflected radio signals.

 

These were all steps in the direction of radar but nothing like positive three­-dimensional identification of objects, or established techniques, existed in early 1935 when Arnold Wilkins made his famous experiment at Daventry, described in News & Views, No. 9, February 1985. (Editor's note - and in this wiki) From that experiment this country embarked, in secret, upon the most forceful development of equipment for detection-at-a-distance by radio, then known as RDF, that had ever been attempted. By stupendous efforts the parameters of wavelength, polarisation, pulse length and repetition frequency, power output and receiver sensitivity were all established.

 

Practical equipment designs were realised in a remarkably short time. Indeed, by September 1938 when Prime Minister Chamberlain flew to Munich to meet Adolf Hitler, his plane was tracked by five RDF stations: Bawdsey, Great Bromley, Canewdon, Dunkirk (Kent) and Dover. A year later, when war broke out, the east coast chain of twenty stations was not only operational day and night but passing range, bearing and height plots via central filter rooms to the integrated air defence system of the RAF!

 

At the 1985 lEE Seminar in London to mark 50 years of radar it was a scientist from abroad who rose to say that, whilst several countries had made minor early contributions to the development of radar, it was the British who, outstandingly, had built a large­-scale, fully-operational radar-based defence system years ahead of anyone else. In the real terms of an effective, long range 3-D early warning system we were undoubtedly ahead: as George Millar puts it in his superb book 'The Bruneval Raid':

 

 '...if the British had failed in many respects to ready themselves for the fight against Nazi Germany. .. they had done wonders with their early warning system; they had been as thorough and as painstaking as they had been inventive. Invisible walls had been built round the United Kingdom, walls twelve miles high and one hundred and twenty miles thick. H.G.Wells himself could never have imagined such defences...'.

 

Yes, the Germans had 'Seetakt' and 'Freya' and 'Wurzburgs' and 'Lichtenstein' and the 'Hummelbett Line' and other things too, and there is no question about the good quality of their equipment.

 

An impressive list of developments? In isolation, perhaps so. But by comparison with the realisation of the full east coast chain by the outbreak of war and the speed with which it was extended, geographically and in wide frequency diversity until literally hundreds of stations existed, working around the clock, it pales into insignificance. We must remember also IFF (Identification Friend or Foe) and the many pulsed beacons, the Army gun-laying and searchlight control sets, the GEE, G-H and OBOE precision bombing/navigational systems, the many airborne, naval and ground-based centimetric sets based on the British cavity magnetron and, perhaps most novel of all, the airborne H2S which enabled aircrew to 'see' otherwise invisible ground below them.

 

With all this in mind we may begin to understand how it was that Reichsmarschall Goring felt bound to comment: 'We must admit that in this sphere the British and Americans are far ahead of us. I expected them to be advanced, but I never thought they would get so far ahead. I did hope that even if we were behind we could at least be in the same race'.

 

Personally, I am saddened when I read published letters implying that, since Germany had some radar equipment early in the war, or even before, the British claim to leadership can be dismissed as a myth! Such a conclusion is grossly unfair to those who worked so hard and so brilliantly. I believe that the matter is confused by the consideration of who may be said to have 'invented' radar. To that question, 'Who invented radar?' many could claim the honours, not least Hillsmeyer, a German engineer who obtained a patent in 1904, long before the enabling technology had materialised. As I mentioned earlier, many could claim that the idea occurred to them because the phenomenon of reflection was observed repeatedly in the course of radio work.

 

But to the question, 'Who first successfully developed radar into an operational defence system?' the answer is unquestionably the British from 1935 onwards. This, I believe, is readily accepted by the Americans too, although they had done promising experimental work before the war. Later, after the transfer of the secrets of the British magnetron (letter M in this series), they were to assist us enormously in equipping our services with radar sets for use in the fight against Germany.

 

 

Latham

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Ian Gillis said

at 2:58 pm on Feb 9, 2016

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