The invention that changed the world: The story of radar from War and Peace

by Buderi Robert

In 1940, a team of British scientists arrived in Washington bearing Britain's most closely guarded technological secrets - including the cavity magnetron, a revolutionary new source of microwave energy. Its arrival triggered the most dramatic mobilization of science in history, as America's top scientists enlisted to convert the invention into a potent military weapon. Microwave radars eventually helped destroy Japanese warships and Nazi buzz bombs, and enabled Allied bombers to "see" through cloud cover. After the war, the work of the radar veterans continues to affect our lives - controlling air traffic, forecasting the weather and providing physicians with powerful diagnostic tools. With anecdotes and revelations, this work explores the work of the scientists who created a winning weapon and changed the world forever.

Genres: History, Science, Nonfiction, Military Fiction, Technology, World War II, Military History

Paperback

First published October 9, 1996

Reviews

[Mike · Rating 5 out of 5]

This book posits the development of radar for WWII led to our modern technological world. The demands of inventing and developing airborne radar, radar guided weapons, proximity fuzes for AAA, long range navigation aids, precision radar detection of periscopes in the Battle of the Atlantic, the need to produce lots of these things very fast would translate to incredible advances after WWII. This book tells the WWII story and then goes on after the war to show how these technologies spawned so many new areas. Fascinating. 5 Battle Stars

I could easily see a Ken Follett novel on German secret agents trying to steal this box on its way to America. One man is carrying Britain’s most secret technological treasures to a ship in Liverpool for the famous Tizard mission that would share these secrets with the US.

THE BLACK JAPANNED METAL deed box could just be seen above the wartime throngs on the shoulder of a railway porter. The small container bobbed along frustratingly out of reach, as Eddie Bowen zigzagged through the crowd in hot pursuit. Only moments before, sometime around 8:15 the morning of August 29, 1940, the Welshman had arrived at London’s Euston Station with the box safely in his possession. Innocently, Bowen had handed it to the porter while gathering up his remaining luggage, then watched helplessly as the man headed off to find the 8:30 train to Liverpool without waiting for his customer.

Inside lay nothing less than the military secrets of Britain, virtually every single technological item the country could bring to bear on the war. Had some freak accident burst the Jack off the chest, the platform would have been awash in blueprints and circuit diagrams for rockets, explosives, superchargers, gyroscopic gunsights, submarine detection devices, self. sealing fuel tanks, and even the initial germs of the jet engine and the atomic bomb.

Among these treasures, nothing carried the all-pervasive importance of the resonant cavity magnetron, Britain’s most closely guarded secret. The black box contained one of the first twelve production copies of the mysterious device, probably the only piece of hardware it sheltered. Small enough to fit in the palm of a hand, the magnetron looked like a clay pigeon used in skeet shooting, with a few couplings thrown in. Yet, it could spit out pulses of microwave radio energy on a wavelength of about ten centimeters, so powerful conventional scientific wisdom still put anything like it years off.

The British had some of the greatest technological inventions but the US has many more labs, factories and capabilities to produce the needed weapon systems. The US side asks for the highest priorities for the UK.
…Bowen and Cockcroft laid out the British needs, giving highest priority to a ten-centimeter airborne interception radar to be fitted in nightfighters: the British considered such a set absolutely vital to stemming the nightly Luftwaffe raids on London. Second on the list was some sort of long-range navigation system for guiding bombers to and from targets without depending on a signal from the plane itself. Third in priority came a ten-centimeter gunlaying radar to direct anti-aircraft fire.

The technological leap offered by the magnetron is hard to quantify but one scientist gives a decent analogy. Plus no one really understood why the magnetron worked as good as it did:

Even those not working directly with the remarkable device (magnetron) were stunned by its potential. “A sudden improvement by a factor of three thousand may not surprise physicists, but it is almost unheard of in engineering,” Luis Alvarez recalled in the mid-1980s, “If automobiles had been similarly: improved, modern cars would cost about a dollar and go a thousand miles on a gallon of gas. We were correspondingly awed by the cavity magnetron. Suddenly it was clear that microwave radar was there for the asking.”

For all its power and promise, however, no one on either side of the Atlantic really fundamentally understood how the strange transmitter worked: somehow in the magnetron’s cylindrical cavities, electrons were accelerated and bunched. into tight coherent packets. In the Rad Lab’s early days, a group of theorists gathered around the tube’s disassembled parts.

“It’s simple,” Rabi told the group. “It’s just a kind of whistle.”

“Okay, Rabi,” said Edward U. Condon, another Berkeley-trained physicist brought in from Westinghouse Research Laboratory, “how does a whistle work?”

The idea of radar begins with a wild idea to build a death ray—kill enemy pilots in the air by raising the temperature of their blood. The idea concludes with Watson-Watt’s famous memo: Detection of Aircraft by Radio Methods. Thank G0d they only practiced science back then and not “The Science” like we have today. People dreamed up all sorts of crazy things and then tried to do them. Of course, today, the scientist would be canceled, ruined, shunned, told to shut up and only work on approved ideas. Back then they saved the free world without worrying whether the investigative thread was politically correct.

Watson Watt prepared a formal statement of the death ray inquiry and passed it on to a trusted junior scientific officer, Arnold F. “Skip” Wilkins. In keeping with his strain of Scottish frugality, the superintendent scrawled the note on an old calendar leaf, which he left on his subordinate’s desk. It read something like: “Please calculate the amount of radio frequency power which should be radiated to raise the temperature of eight pints of water from 98 degrees F to 105 F at a distance of five km and a height of 1 km.”

Despite the Scotsman’s attempt to camouflage the military nature of the assignment, Wilkins saw right away that eight pints of water somehow levitated in space represented an aviator’s blood, and thought immediately of the death ray. His calculations showed that given the technology of the day, generating enough power to raise a man’s temperature enough to kill him could not be even remotely possible. He reported the conclusion to his superior, who replied, “Well, then if the death ray is not possible how can we help them?”

The young scientific officer thought for a moment. He had recently heard that engineers at the government post office, whose dominion extended to shortwave communications, had noticed disturbances when airplanes flew near their receivers. Perhaps this phenomenon could somehow form the basis for an aircraft detection scheme, he mused. Watson Watt seized on the idea, pressing for calculations to establish the effect’s magnitude. Would it be possible, he wondered, to detect planes as far as five or six miles away with the energy from a one-kilowatt transmitter?

Wilkins considered the size of a typical airplane and calculated roughly, to his surprise, that the energy reflected from its surfaces should be detectable. Watson Watt quickly checked the figures. Finding no obvious errors, he included the idea in a memo for Wimperis.

The “radar” Memos:
When the answer came back, it seemed too good to be true. Even allowing generously for losses, Wilkins concluded, at a wavelength of fifty meters, a transmitter sending fifteen amperes of current through a simple aerial should easily produce a detectible echo from planes ten miles distant and flying at an altitude of 20,000 feet. Unable to contain his excitement, Watson Watt hurriedly drafted his 2nd landmark memo, “Detection of Aircraft by Radio Methods,” on February 12, 1935. “It turns out so favourably that I am still nervous as to whether we have not got a power of ten wrong, but even that would not be fatal,” he wrote in a cover note. “I have therefore thought it desirable to send you the memorandum immediately rather than to wait for close rechecking.” The twenty-paragraph epistle, a hallmark of off-the-cuff scientific foresight, formed the basis of Watson Watt's legacy as the father of radar, though the term itself, was coined by the U.S. Navy.

Having used air-to-air and air-to-ground radar throughout my flying career, I am amazed at how clever the first (and many subsequent) guy was trying to solve the problem of airborne radar:

…night fighters needed to be steered to within roughly a thousand feet of their quarry before pilots could see well enough to carry out an attack. ….The Orfordness transmitter (Chain Home radar) alone took up, full room and weighed several tons. Receiver equipment filled another small hut. A practical airborne radar, on the other hand, could take up only about 8 cubic feet and weigh no more than 200 pounds. The meager 500-watt power supply on existing aircraft, already fully occupied serving other systems, highlighted the need for a bigger generator. Given the problems of aerodynamic drag, the antenna must be shrunk to a veritable stub compared to the ground towers, dictating an operating wavelength of close to one meter, much shorter than had so far proven feasible. Finally, any airborne radar needed to be so simple that a pilot or special operator could use it during the rush of combat.

The bigwigs don’t believe their massive investments in radar are paying off fast enough. Dowding goes up in a Fairey Battle on an airborne radar test mission (and gets surprised):

Without seat belts, the two sat side by side on a plank of wood, their heads tucked under the black cloth that shielded the cathode ray screens. Thinking of night-fighting difficulties, Dowding showed particular interest in the minimum range feature — how close the AI set could steer an interceptor to an enemy plane before the echo was lost in the clutter of the radar pulse. The air marshal asked to be notified when the goal had been reached, so that he could see for himself their relation to the target. As Bowen relates it, when the pilot finally gave the cue, Dowding looked around. “Where is it? I can’t see it.” The radar man pointed straight up: the Battle flew almost underneath the other plane. “My God,” ordered Dowding, “tell him to move away, we are too close.”

The great thing about this book is you don’t need engineering or special knowledge to understand the concepts behind radar. He explains in simple, logical passages about:

Determining elevation and azimuth of the enemy plane: the Plan Position Indicator, forerunner of modern radar’s easy-to-read cathode ray tube. In the PPI, a pencil-thin sweep rotates rapidly around the screen, painting in all aircraft within its coverage zone in their exact relationship to the station, dramatically simplifying picture interpretation and obviating the need to convert separate range and azimuth data to a distinct coordinate, steps that avoided confusion and saved precious time directing fighter interceptors toward the enemy

One of the most closely held secrets was the proximity fuze:

In April 1942 the enterprise shifted to a heavily guarded garage building in Silver Spring, Maryland, taking the name Applied Physics Laboratory….the project was kept top secret: plastic noses for the shells were shipped to Johns Hopkins Medical School under the label “recta] spreaders.” By September 1942, American manufacturers led by Sylvania churned out four hundred of the deadly devices a day. The figure would climb to 70,000 daily as the war approached its end.

The proximity fuze, the SCR-584, and the Bell Labs M-9 gun predictor invented by David Parkinson had already seen combat when they joined the anti-aircraft cavalcade rushing to the English south coast in July 1944. But all three had never been used together. The fuze was considered so vital that the Combined Chiefs of Staff banned its use over land, where the enemy might recover enough pieces to design jammers or build a rival version; the decision restricted deployment almost exclusively to the Pacific.

The reign of the V1 Buzz bombs is subjected to both fighters and AAA. AAA incorporates the proximity fuze and the success rates against the V1s shoots up:
deployed to nearly every heavy gun on the Channel coast, the kill rate shot upward. On August 12, General Sir Frederick A, Pile, commander of the British Anti-Aircraft Command, passed on congratulations to General George Marshall, the U.S. Army Chief of Staff: “the curve is going up at a nice pace, and already we are far away ahead of the fighters. As the troops get more expert with the equipment, I have no doubt that very few bombs will reach London.”

Pile’s prediction proved as accurate as the guns. By the fourth week of August, Allied forces were shooting down close to two-thirds of all buzz bombs fired. On the twenty-eighth, the last day V-ls were aimed against Britain in force before Allied troops overran launching sites near the Strait of Dover, the Germans fired 104 across the Channel. Artillery got sixty-eight. Fighters shot down fourteen. Barrage balloons accounted for two more, and sixteen crashed before reaching their targets. Only four hit London. All told, over the nearly three-month campaign, anti-aircraft batteries brought down 1629 buzz bombs, almost equaling the fighter total. After the move to the coast, the guns outshot aircraft by 50 percent, registering some 1300 kills, virtually all with 584-controlled guns and the proximity fuze.

Nice video of proximity fuze development: https://www.youtube.com/watch?v=Dtocp...

[Benjamin · Rating 4 out of 5]

This history of radar is a fascinating topic and is a nice counterpoint to other WWII history I've read (like Hodges's Alan Turing) that emphasizes the role of codebreaking. It was also eye-opening to see just how much methods of technical management developed by the US and UK during WWII led to models of academic/government/industrial partnership and research that survive to the present day. More broadly, the book was a slog and I struggled to stay engaged.

In Chapter 3, titled "Beginnings", Buderi briefly compares (the relatively rare) discoveries that arise from "original thinking" (his canonical example is special relativity) to (the more common and inevitable) discoveries caused by humanity's slow acquisition of knowledge, signaled by some combination of incremental change, people who can translate knowledge or intuition from one field to another, and simultaneous invention.

In Chapter 4, titled "A Line in the Ether", Buderi says "the cavity magnetron was invented accidentally on purpose"; the cavity magnetron uses open cavities in the device to create microwaves from an electric current.

Chapter 7, titled "Battle for the Atlantic", includes a passage praising "the more aggressive philosophy of attacking with a bucketful of science."

The contrast in Chapter 9 (titled "Tangled Web") between the vast effort devoted to developing radar capabilities versus the entrenched resistance (at first) to the assumption that Germany was pursuing similar lines of research and countermeasures was very interesting. The same chapter also outlines the Oslo Report. Probably the most exciting passage in the book occurs in the description of the Bruneval Raid to recover pieces of a German gun-laying Wurzburg.

Chapter 10, titled "Victory", has a section, immediately following the quote below, that describes the way Japanese bureaucracy and infighting in their military branches hobbled what could have been some solid radar research.

my favorite quote: "The Japanese, as soon became evident, had forsaken the Wizard War."

[Dan Cohen · Rating 3 out of 5]

This is a good account of the development of radar technology, focusing on the work of the MIT Radiation Laboratory. Well written and well researched, and it tells an interesting story.

I would have liked less of a focus on MIT and, especially, a more international view. I was also left a bit confused on the famous cavity magnetron - on the one hand the initial development of the device by the British is made to sound like it was of enormous importance, but on the other hand there are small references to similar developments elsewhere, which made me think that the British development was just one of many and hence not that significant.

[Ruth · Rating 2 out of 5]

c1998 (16) FWFTB: radar, Europe,magnetrons, screens and antennae. This is a weighty book. Not only in terms of content but in actual weight. It is 575 pages but it weighs a ton. Surprisingly interesting and the technical aspects were well explained. Recommended to the boffins within the normal crew. " To an untrained eye, the path seemed to go all the way to the house, as if providing an access road for radar operators bunked inside."

[Bill Yancey · Rating 5 out of 5]

The atomic bomb ended WWII, but Tesla and Marconi's radio waves, developed into radar, actually won the war for the Allies and laid the basis for the modern electronic world we live in. This book documents that history in a very interesting and educational way. Great book.

[Douglas Hardy · Rating 4 out of 5]

Dense but wonderfully readable story of the earliest work in radar and electronics. The war changed everything, including science and engineering, setting the stage for the electronics revolution of the 1950s.

[Patrick · Rating 5 out of 5]

A great story about what it took to win WWII from a specific scientific viewpoint. Some of the reading is quite thrilling, with heroes and villains, spies and soldiers, along with plenty of politics.

[Mark Smith · Rating 4 out of 5]

Extensive review of the development of radar during WWII. Excellent writing and interesting, but perhaps a bit more detailed accounts of personalities etc. than I needed.

[Richard Arvedson · Rating 4 out of 5]

Great discussion of the invention that won World War II. Had a personal interest in reading this book. It has waited on a shelf for many years, but I finally did the right thing. I read it.

[Christian D'Amico · Rating 3 out of 5]

Wish this focused more on the British point of view. Good historical account.

[Ushan · Rating 3 out of 5]

Radar, or sending a radio wave in a certain direction, waiting for it to reflect off some object, and judging the distance to the object by the delay and its size by the strength of the echo signal, was invented in Great Britain shortly before World War II. It was used by the British during the Battle of Britain and the Blitz to find German bombers, by the Germans in the strategic bombing campaign to find British and American bombers, which themselves used radar to find targets on the ground, by the British and the Americans during the Battle of the Atlantic to find German U-boats. Later in the war, American antiaircraft artillery directed by an electromechanical computer fed by a radar proved effective against the German V-1 cruise missile. The proximity fuse is a mini-radar in an artillery shell that detonates it near the target; a weapon feared by the German infantry late in the war was a shell with a proximity fuse that rained shrapnel upon German trenches. A crucial invention was the cavity magnetron, invented in Great Britain, brought to the United States by the Tizard mission; over a million were manufactured by the end of the war.

Baderi shoehorns chapters on the invention of the transistor and the maser to the book by their connection to wartime radar work: the transistor arose from the need to amplify a radar echo with less noise than the vacuum tube, which needs to use something colder than a glowing vacuum tube filament; the maser arose from the wartime discovery that at some frequencies the radar doesn't work in bad weather because moisture in the air absorbs the microwaves; what if water molecules or some other gas molecules are made to absorb and then re-radiate microwaves?

An important postwar application of the radar was in astronomy, especially that of the doppler radar, which judges not only the distance to its target and its size but also its velocity. The echo of a radar pulse sent at the center of the Moon will come back not all at once, but gradually over concentric rings; because the Moon is turning on its axis, each point in a half-ring folded around the Moon's equator will reflect the signal at a different frequency. The near side of the Moon was thus radar-mapped before the first space probes landed on it. Doppler radar also discovered the rotation of Venus and Mercury. Because Venus is covered in clouds opaque to visible light, its topography has to be mapped by radar, and it was in the Soviet Venera 15 and 16 and the American Magellan missions.

[Glenn · Rating 5 out of 5]

One of the best books to start one's reading on Radar history. Leans a bit more towards the US perspective and experience.

This focuses on the development of Radar in the US, following the Tizard mission (which delivered the cavity magnetron), beginning with a focus on the MIT Rad Lab. It covers technology exchanges back and forth between the US & UK covering aircraft interception, anti-ship / anti-submarine radar, gun-laying radar, and initiatives to guide planes to target destinations in poor weather. But, what makes this different from most of the other WWII books on Radar I've read is the extensive coverage of the post-war applications of the technology, and careers of the key technologists and physicists -- including everything from radio astronomy to the radar range.

If I were going to limit my Radar studies to a single book, this one has the kind of broad coverage I would want.

[Kyle Zufelt · Rating 4 out of 5]

This book provides a fascinating overview of the development of RADAR among the allies in World War 2. My biggest complaint about the book is that I went into it expecting the book to end with the end of WW2, but it instead spent about half of the book discussing the development of post-war applications like radio astronomy. If you are interested in the technology and implications of RADAR, this is a fantastic book about the less popular brother of the nuclear bomb project.

[Dan · Rating 5 out of 5]

A relative who was in the US Army Signal Corps went to Great Britain in 1940 to learn about radar technology. He was also radio man on RAF sub hunters. I have photos of some of his planes with the radar info on back. He told me that this was the best book about radar (in the war) that he had read.

[Steve · Rating 5 out of 5]

Excellent history of the Development of Radar here in the United States.